Piping components and rain gutter systems

Abstract

To provide a piping member and a rain gutter system capable of stably promoting the action of a siphon phenomenon.SOLUTION: A piping member 5 constitutes a part of a down-pipe 3 of a rain gutter system 1 which uses a siphon phenomenon for draining rainwater. The piping member 5 comprises: a straight pipe part 51 which defines at least a part of a flow path 30 of the down-pipe 3; and a discharge part 52 which is connected to the straight pipe part 51 and is disposed in the flow path 30. The discharge part 52 has: an opening 521 which has a flow path area smaller than that of the straight pipe part 51; and a guide surface 522 which guides rainwater passing through the opening 521 in a direction approaching a center axis C1 of the straight pipe part 51.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a piping member and a rain gutter system.

Background Art

[0002] Patent Document 1 discloses a rain gutter system. The rain gutter system disclosed in Patent Document 1 includes an eaves gutter, a downspout, a connection joint that is disposed on the downstream side of the eaves gutter and is continuous with the upper end of the downspout, and a siphon joint that has a reduced-diameter portion and is provided in the downspout.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the rain gutter system of Patent Document 1, the reduced-diameter portion causes a pressure loss, and turbulent flow occurs immediately below the reduced-diameter portion. Therefore, the siphon phenomenon is interrupted at the siphon joint.

[0005] The present disclosure provides a piping member and a rain gutter system that can stably promote the action by the siphon phenomenon.

Means for Solving the Problems

[0006] A piping member according to an aspect of the present disclosure is a piping member that constitutes a part of a downspout of a rain gutter system that utilizes the siphon phenomenon for draining rainwater, and includes a straight pipe portion that defines at least a part of the flow path of the downspout, and a discharge portion that is coupled to the straight pipe portion and is disposed in the flow path. The discharge portion has an opening with a smaller flow area than the straight pipe portion, and a guide surface that guides rainwater passing through the opening toward the central axis of the straight pipe portion.

[0007] A rain gutter system according to one aspect of the present disclosure comprises a downpipe having the above-mentioned piping members and connected to a rainwater outlet from a building, and a drain positioned at the outlet. [Effects of the Invention]

[0008] Aspects of this disclosure can stably promote the action due to the siphon phenomenon. [Brief explanation of the drawing]

[0009] [Figure 1] Schematic diagram of an example configuration of a rain gutter system equipped with piping members according to Embodiment 1. [Figure 2] Perspective view of an example of the piping component configuration in Figure 1. [Figure 3] Cross-sectional view of the piping member in Figure 2. [Figure 4] Diagram illustrating the operation of piping components (Figure 2) [Figure 5] Figure 1 is an explanatory diagram of the rain gutter system used for drainage. [Figure 6] Schematic diagram of an example configuration of a rain gutter system equipped with piping members according to Embodiment 2. [Figure 7] Figure 6 is an explanatory diagram of the rain gutter system for drainage. [Figure 8] Cross-sectional view of the configuration example of the piping member in Modification Example 1 [Figure 9] Cross-sectional view of the configuration example of the piping member in modified example 2. [Figure 10] Cross-sectional view of the configuration example of the piping member in modified example 3. [Figure 11] Cross-sectional view of the configuration example of the piping member in modified example 4. [Figure 12] Cross-sectional view of the configuration example of the piping member in modified example 5. [Figure 13] Cross-sectional view of the configuration example of the piping member in modified example 6. [Figure 14] Cross-sectional view of the configuration example of the piping member in modified example 7. [Figure 15] Cross-sectional view of the example piping component configuration of modified example 8. [Figure 16] Cross-sectional view of the configuration example of the piping member in modified example 9. [Figure 17]Schematic diagram of a configuration example of a rain gutter system including the pipe member of Modification 10 [Figure 18] Cross-sectional view of a configuration example of the pipe member of Modification 11

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, detailed descriptions that are more than necessary may be omitted. For example, detailed descriptions of well-known matters and duplicate descriptions of substantially the same configurations may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate the understanding of those skilled in the art. Note that the inventors provide the accompanying drawings and the following description so that those skilled in the art can fully understand the present disclosure, and do not intend to limit the subject matter described in the claims thereby.

[0011] The positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Each of the drawings described in the following embodiments is a schematic diagram, and the ratios of the sizes and thicknesses of each component in each drawing do not necessarily reflect the actual dimensional ratios. Also, the dimensional ratios of each element are not limited to the ratios shown in the drawings.

[0012] [1. Embodiment] [1.1 Embodiment 1] [[ID=2,3]][1.1.1 Configuration] FIG. 1 is a schematic diagram of a configuration example of a rain gutter system 1 according to Embodiment 1. The rain gutter system 1 receives rainwater from the roof 11a of the building 11 and flows it to the catchment part 2 of the ground 20. The rainwater collected in the catchment part 2 flows out to the rainwater pipe through the buried pipe 22 from the catchment part 2. The building 11 is, for example, a building of a non-residential facility such as a store, an office, a factory, a building, a school, a welfare facility or a hospital, and a residential facility such as a detached house, an apartment house, or each household of a detached house or an apartment house. Non-residential facilities also include theaters, cinemas, halls, game arcades, complex facilities, department stores, hotels, inns, kindergartens, libraries, museums, art galleries, underground shopping streets, stations, airports, etc.

[0013] The rain gutter system 1 in Figure 1 comprises a gutter 2, a downpipe 3, and a drain 4.

[0014] The gutter 2 receives rainwater from the roof 11a of the building 11. The gutter 2 is installed beneath the roof 11a of the building 11. The gutter 2 is long and barrel-shaped. The gutter 2 in Figure 1 has a bottom wall 2a. There is a drain outlet 2b in the bottom wall 2a.

[0015] Drain 4 is positioned at the outlet 2b of the gutter 2. Drain 4 reduces the generation of vortices and air entrainment at the outlet 2b. Drain 4 may contribute to the generation of a siphon effect. Drain 4 may have a well-known configuration.

[0016] The downpipe 3 is installed to drain rainwater from the outlet 2b. The downpipe 3 has a channel 30 for vertically draining rainwater from the outlet 2b. In the downpipe 3 shown in Figure 1, no branch pipes from gutters other than the one in the gutter 2 are connected to the channel 30. In other words, the downpipe 3 is configured so that rainwater from outlets other than the one in the gutter 2b does not flow into the channel 30.

[0017] The downpipe 3 has an upstream end 3a and a downstream end 3b. The upstream end 3a is the end of the downpipe 3 that is connected to the outlet 2b (the upper end in Figure 1). In Figure 1, the downpipe 3 is directly connected to the outlet 2b. That is, rainwater falls vertically from the outlet 2b into the flow path 30 of the downpipe 3 and flows into the manhole 21. The downstream end 3b is the end of the downpipe 3 that is inserted into the manhole 21 (the lower end in Figure 1). In Figure 1, a drain pipe cover 34 is positioned to prevent rainwater from flowing into the manhole 21 through the gap between the downpipe 3 and the manhole 21.

[0018] In Figure 1, the downpipe 3 is fixed to the wall surface 11b of the building 11 by bracing brackets 33a, 33b, and 33c. The distance from the ground 20 to the top end of the downpipe 3 [mm], the distance from the top end of the downpipe 3 to the uppermost bracing bracket 33a [mm], and the distance from the ground 20 to the lowermost bracing bracket 33c [mm] are generally between 200 mm and 300 mm. The pitch [mm] between bracing brackets 33a, 33b, and 33c is generally between 800 mm and 1200 mm, and in certain cases, it is 1000 mm or less. The distance between the downpipe 3 and the wall surface 11b is generally between 30 mm and 100 mm.

[0019] The downpipe 3 in Figure 1 comprises a first vertical pipe 31, a second vertical pipe 32, and a piping member 5.

[0020] The first vertical pipe 31 constitutes a part of the flow path 30 of the downpipe 3. In this embodiment, the internal space enclosed by the inner surface 31a of the first vertical pipe 31 becomes a part of the flow path 30 of the downpipe 3. In this embodiment, the first vertical pipe 31 is the upstream part of the downpipe 3. The first vertical pipe 31 is a straight pipe. The cross-section perpendicular to the pipe axis of the first vertical pipe 31 is circular. The material of the first vertical pipe 31 is rigid polyvinyl chloride. The dimensions of the first vertical pipe 31, for example, the outer shape and thickness, may be set in accordance with the standard for rigid polyvinyl chloride pipes (general) of JIS K 6741 "Rigid Polyvinyl Chloride Pipe". The first vertical pipe 31 is fixed to the wall surface 11b of the building 11 so that the direction of the pipe axis of the first vertical pipe 31 coincides with the vertical direction. The upper end of the first vertical pipe 31 is the upstream end 3a of the downpipe 3.

[0021] The second vertical pipe 32 constitutes a part of the flow path 30 of the downpipe 3. In this embodiment, the internal space enclosed by the inner surface 32a of the second vertical pipe 32 becomes a part of the flow path 30 of the downpipe 3. The internal space of the second vertical pipe 32 becomes a part of the flow path 30 of the downpipe 3. The second vertical pipe 32 is the downstream part of the downpipe 3. The second vertical pipe 32 is a straight pipe. The cross-section perpendicular to the pipe axis of the second vertical pipe 32 is circular. The material of the second vertical pipe 32 is rigid polyvinyl chloride. The dimensions of the second vertical pipe 32, for example, the outer shape and thickness, may be set in accordance with the standard for rigid polyvinyl chloride pipes (general) of JIS K 6741 "Rigid Polyvinyl Chloride Pipe". The second vertical pipe 32 is fixed to the wall surface 11b of the building 11 so that the direction of the pipe axis of the second vertical pipe 32 coincides with the vertical direction. The lower end of the second vertical pipe 32 is the downstream end 3b of the downpipe 3. End 3b is also the part of the downpipe 3 that is open to the atmosphere.

[0022] In the downpipe 3 shown in Figure 1, the diameter (inner and outer diameter) of the first vertical pipe 31 is equal to the diameter (inner and outer diameter) of the second vertical pipe 32. In other words, pipe materials corresponding to the same nominal diameter can be used for both the first vertical pipe 31 and the second vertical pipe 32.

[0023] The piping member 5 constitutes part of the downpipe 3 of the rain gutter system 1, which utilizes the siphon effect for rainwater drainage. The piping member 5 is provided in the rain gutter system 1 to stably promote the effect of the siphon effect. In the downpipe 3 shown in Figure 1, the piping member 5 is located between the first vertical pipe 31 and the second vertical pipe 32. The piping member 5 in Figure 1 may be a socket connecting pipes. The position of the piping member 5 in the downpipe 3 is set appropriately considering the degree to which the siphon effect occurs during rainwater drainage.

[0024] The piping member 5 in Figure 1 comprises a straight pipe section 51 and a discharge section 52. The piping member 5 will be further described below with reference to Figures 2 and 3. Figure 2 is a perspective view of an example configuration of the piping member 5. Figure 3 is a cross-sectional view of the piping member 5.

[0025] The straight pipe section 51 defines at least a portion of the flow path 30 of the downpipe 3. In this embodiment, the internal space of the straight pipe section 51, surrounded by the inner surface 510 of the straight pipe section 51, becomes part of the flow path 30 of the downpipe 3. As is clear from Figure 2, the cross-section perpendicular to the central axis C1 of the straight pipe section 51 is circular. The central axis C1 of the straight pipe section 51 is also the pipe axis of the straight pipe section 51. The material of the straight pipe section 51 is rigid polyvinyl chloride. The dimensions of the straight pipe section 51, for example, the outer shape and thickness, may be set in accordance with the standard for rigid polyvinyl chloride pipes (general) of JIS K 6741 "Rigid Polyvinyl Chloride Pipe". The straight pipe section 51 is arranged such that the direction of the central axis C1 of the straight pipe section 51 coincides with the vertical direction.

[0026] As shown in Figure 3, the straight pipe section 51 has a first end 51a and a second end 51b, and an intermediate section 51c between the first end 51a and the second end 51b, in the direction of the central axis C1.

[0027] The first end portion 51a is directed towards the upstream side of the downpipe 3. As shown in Figure 3, the first end portion 51a is connected to the lower end of the first vertical pipe 31. In this embodiment, the outer dimensions of the first end portion 51a are smaller than those of the intermediate portion 51c, and it is sized to be inserted into the first vertical pipe 31. The length of the first end portion 51a in the direction of the central axis C1 may be set appropriately to ensure a stable connection between the piping member 5 and the first vertical pipe 31. As shown in Figure 3, the second end portion 51b is connected to the upper end of the second vertical pipe 32. In this embodiment, the outer dimensions of the second end portion 51b are smaller than those of the intermediate portion 51c, and it is sized to be inserted into the second vertical pipe 32. In this embodiment, the outer dimensions of the second end portion 51b are equal to those of the first end portion 51a. The length of the second end portion 51b in the direction of the central axis C1 may be set appropriately to ensure a stable connection between the piping member 5 and the second vertical pipe 32. In Figure 3, the internal dimensions of the first end 51a, the second end 51b, and the intermediate section 51c are equal.

[0028] As shown in Figures 2 and 3, the straight pipe section 51 has an opening 511 at its first end 51a. In this embodiment, the opening 511 defines the inlet of the piping member 5. Therefore, in the downpipe 3, rainwater from the first vertical pipe 31 enters the internal space of the straight pipe section 51 through the opening 511, which is the inlet of the straight pipe section 51.

[0029] As shown in Figure 2, the straight pipe section 51 has a mark 51d. The mark 51d indicates the orientation for installing the piping member 5. The mark 51d in Figure 2 is an arrow, and when installing the piping member 5, the piping member 5 should be installed so that the arrow indicated by the mark 51d points upward. The mark 51d in Figure 2 is located on the outer surface of the first end 51a. When the piping member 5 is connected to the first vertical pipe 31, the mark 51d is hidden by the first vertical pipe 31. The mark 51d may be a letter, figure, symbol, three-dimensional shape, or color, or a combination thereof, that is recognizable by human perception.

[0030] The discharge section 52 is connected to the straight pipe section 51 and positioned in the flow path 30. In this embodiment, as shown in Figure 3, the discharge section 52 is located at the second end 51b of the straight pipe section 51. In this embodiment, the discharge section 52 is formed integrally with the straight pipe section 51 and is therefore connected to the straight pipe section 51. The material of the discharge section 52 is rigid polyvinyl chloride, the same as that of the straight pipe section 51.

[0031] As shown in Figures 2 and 3, the discharge section 52 includes a partition wall section 53 and a guide section 54.

[0032] The partition wall 53 extends from the inner surface 510 of the straight pipe section 51 toward the central axis C1 of the straight pipe section 51. The partition wall 53 is a plate-like structure with a uniform thickness. The partition wall 53 has an opening 521. As a result, the opening 521 is located inside the straight pipe section 51. In other words, the discharge section 52 is connected to the straight pipe section 51 such that the opening 521 is located inside the straight pipe section 51.

[0033] In this embodiment, the opening 521 is located in the center of the partition wall 53. Viewed from the direction of the central axis C1 of the straight pipe section 51, the partition wall 53 is annular. The flow area of ​​the opening 521 is smaller than that of the straight pipe section 51. In this embodiment, in a plane perpendicular to the central axis C1 of the straight pipe section 51, both the opening 521 and the internal space of the straight pipe section 51 are circular. In this embodiment, the inner diameter D2 of the opening 521 is smaller than the inner diameter D1 of the straight pipe section 51. As shown in Figure 2, in this embodiment, the center O1 of the opening 521 lies on the central axis C1 of the straight pipe section 51. As shown in Figure 3, in this embodiment, the edge of the opening 521 is rounded (R-shaped).

[0034] The guide portion 54 protrudes from the edge of the opening 521 of the partition wall portion 53 toward the downstream side of the downpipe 3, for example, toward the second end 51b of the straight pipe portion 51 from the first end 51a. The guide portion 54 surrounds the entire circumference of the opening 521. In this embodiment, the guide portion 54 is hollow and frustum-shaped. A frustum is a shape obtained by removing a similarly scaled-down cone that shares a vertex with the cone from a cone. The outer and inner circumferential shapes of the guide portion 54 in a plane perpendicular to the central axis C1 of the straight pipe portion 51 are circular. The outer and inner circumferential shapes of the guide portion 54 in a plane perpendicular to the central axis C1 of the straight pipe portion 51 become smaller toward the second end 51b of the straight pipe portion 51 from the first end 51a.

[0035] In this embodiment, the inner circumferential surface of the guide portion 54 functions as a guide surface 522 for rainwater passing through the opening 521. The guide surface 522 faces inward towards the straight pipe portion 51. "Facing inward towards the straight pipe portion 51" means that the guide surface 522 faces the central axis C1 of the straight pipe portion 51. The guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe portion 51. In this embodiment, the guide surface 522 approaches the central axis C1 of the straight pipe portion 51 as it moves downstream from the opening 521 towards the downpipe 3. In this embodiment, the inclination of the guide surface 522 is constant. That is, the increment of the distance between the guide surface 522 and the central axis C1 in the plane perpendicular to the central axis C1 of the straight pipe portion 51 relative to the distance from the opening 521 is constant.

[0036] The discharge section 52 has an opening 523 on the opposite side of the opening 521 in the guide section 54. In this embodiment, the opening 523 defines the outlet of the piping member 5. Therefore, in the downpipe 3, rainwater from the piping member 5 enters the second vertical pipe 32 through the opening 523, which is the outlet of the piping member 5. In this embodiment, the inner diameter D3 of the opening 523 is smaller than the inner diameter D2 of the opening 521.

[0037] Next, the operation of the piping component 5 will be explained. Figure 4 is an explanatory diagram of the operation of the piping component 5. When rainwater W begins to flow into the downpipe 3 from the outlet 2b, the rainwater W falls through the downpipe 3 along the pipe wall of the downpipe 3 (in Figure 4, the inner surface 31a of the first vertical pipe 31). In other words, when the siphon effect is not occurring, the flow of rainwater W generally falls from the outlet 2b along the pipe wall of the downpipe 3 and reaches the discharge part 52 of the piping component 5.

[0038] As described above, the piping member 5 is located between the first vertical pipe 31 and the second vertical pipe 32 of the downpipe 3. The piping member 5 includes a discharge section 52 positioned within the flow path 30 of the downpipe 3. The discharge section 52 has an opening 521 and a guide surface 522.

[0039] The opening 521 has a smaller flow path area than the straight pipe section 51. A reduction in flow path area can cause an increase in the flow velocity of rainwater W. Therefore, the discharge section 52 increases the flow velocity of rainwater W through the opening 521 and directs it towards the guide surface 522.

[0040] The guide surface 522 directs the rainwater W passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52, with the help of the guide surface 522, converges the rainwater W that has passed through the opening 521 toward the central axis C1 of the downpipe 3. From this perspective, the discharge section 52 can also be said to be a convergence section that converges the rainwater W.

[0041] As described above, when rainwater W begins to flow into the downpipe 3 from the outlet 2b, the rainwater W falls along the inner surface of the downpipe 3, causing the air inside the downpipe 3 to gather towards the central axis C1, creating an air layer. This air layer is one of the factors that prevents the downpipe 3 from becoming completely full. However, in the piping member 5, the discharge section 52 directs the rainwater W toward the central axis C1 of the downpipe 3. As a result, the rainwater W actively collides with the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater W experiences air resistance, the flow velocity of the rainwater W may decrease below the discharge section 52. As a result, the area downstream of the discharge section 52 in the downpipe 3 is more likely to become completely full than the area upstream of the discharge section 52 in the downpipe 3. In other words, the discharge section 52 actively directs the rainwater W into the air layer inside the downpipe 3, pushing the air layer out of the downpipe 3 and filling the space between the discharge section 52 and the downstream end 3b of the downpipe 3 with water. In particular, the opening 521 increases the flow velocity of the rainwater W, allowing the rainwater W to hit the air layer more strongly, thereby promoting the reduction of the air layer. In this embodiment, the term "full water state" is not used in a strict sense and includes a state that is filled with water to an extent that can be considered equivalent to a full water state (a state close to a full water state).

[0042] The presence of a discharge section 52 in the piping member 5 allows for the intentional creation of a waterlogged area in the downpipe 3 of the rain gutter system 1. Figure 5 is an explanatory diagram of drainage by the rain gutter system 1. As shown in Figure 5, the piping member 5 can create a waterlogged area in the downpipe 3 between the position HP of the discharge section 52 and the position LP of the downstream end 3b.

[0043] One factor contributing to the siphon effect is the difference in potential energy between the upper and lower ends of the water surface when viewed from the vertical. The larger the difference in potential energy, the greater the increase in flow velocity due to the siphon effect, which is thought to increase the flow rate. In the case of Figure 5, the longer the vertical length of the area in the downpipe 3 that is filled with water, that is, the longer the distance H1 between the position HP of the discharge section 52 and the position LP of the downstream end 3b in the vertical direction, the greater the negative pressure at the discharge section 52, and the greater the suction force due to the siphon effect can be. As a result, the piping member 5 can stably promote the effect of the siphon effect.

[0044] In the rain gutter system 1 shown in Figure 1, the downpipe 3 is directly connected to the outlet 2b, so rainwater from the outlet 2b falls freely within the flow path 30 of the downpipe 3. However, the piping member 5 has a discharge section 52, which allows the velocity of the rainwater falling within the flow path 30 of the downpipe 3 to be controlled. This makes it possible to satisfy the conditions for the siphon effect to occur in the downpipe 3. The discharge section 52 concentrates the rainwater and directs it into the air layer below the discharge section 52, thereby stably creating a full-water state downstream of the discharge section 52 and stabilizing the effect of the siphon effect. In particular, by providing the discharge section 52, it is not necessary to reduce the diameter of the downpipe 3, and the drainage performance of the downpipe 3 itself is not significantly reduced.

[0045] The position of the piping member 5 in the downpipe 3 can be appropriately set according to the pipe diameter of the downpipe 3, the amount of rainwater passing through the downpipe 3, the installation environment of the rain gutter system 1, and various other conditions. For example, the position of the piping member 5 in the downpipe 3 may be set so as to obtain a desired difference in potential energy, taking into account the amount of rainwater expected at the installation site of the rain gutter system 1. For example, the position of the piping member 5 in the downpipe 3 may be set so that the distance H1 is a value that obtains a desired difference in potential energy.

[0046] [1.1.2 Effects, etc.] The piping member 5 described above constitutes a part of the downpipe 3 of the rain gutter system 10, which utilizes the siphon effect for rainwater drainage. The piping member 5 comprises a straight pipe section 51 that defines at least a part of the flow path 30 of the downpipe 3, and a discharge section 52 that is connected to the straight pipe section 51 and positioned in the flow path 30. The discharge section 52 has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0047] In the piping member 5, the guide surface 522 approaches the central axis C1 of the straight pipe section 51 as it moves downstream from the opening 521 towards the downpipe 3. This configuration makes it easier to guide rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51, thereby further stably promoting the effect of the siphon phenomenon.

[0048] In the piping member 5, the length of the guide surface 522 in the direction of the central axis C1 of the straight pipe section 51 is set such that the downstream side of the discharge section 52 in the downpipe 3 becomes full of water before the upstream side of the discharge section 52 in the downpipe 3. This configuration can stably promote the effect of the siphon phenomenon.

[0049] In the piping member 5, the edge of the opening 521 is rounded (R-shaped). This configuration reduces losses at the edge of the opening 521.

[0050] In the piping member 5, the center O1 of the opening 521 lies on the central axis C1 of the straight pipe section 51. This configuration allows for stable promotion of the siphon effect.

[0051] The rain gutter system 1 described above includes a downpipe 3 having a piping member 5 and connected to a rainwater outlet 2b from the building 11, and a drain 4 located at the outlet 2b. This configuration can stably promote the action due to the siphon effect.

[0052] In the rain gutter system 1, the downpipe 3 is directly connected to the outlet 2b. This configuration can stably promote the action caused by the siphon phenomenon.

[0053] [1.2 Embodiment 2] [1.2.1 Structure] Figure 6 is a schematic diagram of an example configuration of the rain gutter system 10 according to Embodiment 2. The rain gutter system 10 receives rainwater from the roof 11a of the building 110 and directs it to a drain section 21 on the ground 20. The rainwater collected in the drain section 21 flows out of the drain section 21 through the buried pipe 22 into the rainwater pipe. The building 110, like building 11, is a building of non-residential facilities such as shops, offices, factories, office buildings, schools, welfare facilities or hospitals, and residential facilities such as detached houses, apartment buildings, or individual dwelling units in detached houses or apartment buildings. Non-residential facilities also include theaters, cinemas, public halls, amusement parks, complexes, department stores, hotels, inns, kindergartens, libraries, museums, art galleries, underground shopping malls, train stations and airports.

[0054] Building 110 has a longer eaves than building 11 described in Embodiment 1. In building 110, if the downpipe 3 is directly connected to the drain outlet 2b, the distance between the downpipe 3 and the wall surface 11b of building 110 becomes large, and the construction standards for the downpipe 3 are no longer met. The rain gutter system 10 of this embodiment has a structure suitable for building 110 with long eaves. The rain gutter system 10 in Figure 6 comprises an eaves gutter 2, a downpipe 3, a drain 4, a connecting downpipe 6, a first elbow 7a, a second elbow 7b, and an auxiliary downpipe 8.

[0055] The eaves gutter 2, downpipe 3, and drain 4 of the rain gutter system 10 in Figure 6 are the same as the eaves gutter 2, downpipe 3, and drain 4 of the rain gutter system 1 in Figure 1.

[0056] In the rain gutter system 10, the downpipe 3 is not directly connected to the outlet 2b. In the rain gutter system 10, the downpipe 3 is connected to the outlet 2b via the connecting pipe 6, the first elbow 7a, and the second elbow 7b.

[0057] The downpipe 6 is the section that directs rainwater from the building 110 from the outlet 2b to the downpipe 3. The downpipe 6 is located between the rainwater outlet 2b and the downpipe 3. The downpipe 6 is a straight pipe. The cross-section of the downpipe 6 perpendicular to its axis is circular. The material of the downpipe 6 is rigid polyvinyl chloride. In Figure 6, the downpipe 6 is fixed so that the direction of its axis is inclined with respect to the vertical direction.

[0058] The downpipe 6 has an upstream end 6a and a downstream end 6b. The upstream end 6a is the end of the downpipe 6 that connects to the outlet 2b (the upper end in Figure 6). The downstream end 6b is the end of the downpipe 6 that connects to the downpipe 3 (the lower end in Figure 6). The downpipe 6 is cylindrical. The material of the downpipe 6 is rigid polyvinyl chloride. The dimensions of the downpipe 6, for example, the outer diameter and thickness, may be set in accordance with the standard for rigid polyvinyl chloride pipes (general) of JIS K 6741 "Rigid Polyvinyl Chloride Pipes".

[0059] The first elbow 7a connects the upstream end 6a of the downpipe 6 to the outlet 2b. The first elbow 7a is not necessarily a member that directly connects the upstream end 6a of the downpipe 6 to the outlet 2b, but may be a member that indirectly connects the upstream end 6a of the downpipe 6 to the outlet 2b via another member. The material of the first elbow 7a is, for example, rigid polyvinyl chloride. The first elbow 7a has sockets 71a and 72a for connecting pipe materials such as the downpipe 3 and the downpipe 6 to the first elbow 7a. The angle between the central axes of the sockets 71a and 72a is, for example, 91.17° as specified in JIS K 6739 "Rigid polyvinyl chloride pipe fittings for drainage". The inner and outer corners of the first elbow 7a in the plane containing the pipe axis of the first elbow 7a are approximately right angles, not R-shaped.

[0060] The second elbow 7b connects the downstream end 6b of the downpipe 6 to the upstream end 3a of the downpipe 3. The second elbow 7b is not necessarily a member that directly connects the downstream end 6b of the downpipe 6 to the upstream end 3a of the downpipe 3, but may be a member that indirectly connects the downstream end 6b of the downpipe 6 to the upstream end 3a of the downpipe 3 via another member. The material of the second elbow 7b is, for example, rigid polyvinyl chloride. The second elbow 7b has sockets 71b and 72b for connecting pipe materials such as the downpipe 3 and the downpipe 6 to the second elbow 7b. The angle between the central axes of the sockets 71b and 72b is, for example, 91.17° as specified in JIS K 6739 "Rigid polyvinyl chloride pipe fittings for drainage". The inner and outer corners of the second elbow 7b in the plane containing the pipe axis of the second elbow 7b are approximately right angles, not R-shaped.

[0061] The dimensions of the first elbow 7a and the second elbow 7b may be set in accordance with, for example, the JIS K 6739 standard for rigid polyvinyl chloride pipe fittings for drainage. At least one of the first elbow 7a and the second elbow 7b may be a 90° bend elbow as defined in JIS K 6739.

[0062] The auxiliary downpipe 8 is the section that allows rainwater from the building 110 to flow vertically from the outlet 2b to the first elbow 7a. The auxiliary downpipe 8 is located between the outlet 2b and the first elbow 7a. The auxiliary downpipe 8 is a straight pipe. The cross-section of the auxiliary downpipe 8 perpendicular to its pipe axis is circular. The material of the auxiliary downpipe 8 is rigid polyvinyl chloride. The dimensions of the auxiliary downpipe 8, for example, its outer shape and thickness, may be set in accordance with the standard for rigid polyvinyl chloride pipes (general) of JIS K 6741 "Rigid Polyvinyl Chloride Pipe". In Figure 6, the auxiliary downpipe 8 is positioned between the outlet 2b and the first elbow 7a so that the direction of the pipe axis of the auxiliary downpipe 8 coincides with the vertical direction.

[0063] The auxiliary downpipe 8 has an upstream end 8a and a downstream end 8b. The upstream end 8a is the end of the auxiliary downpipe 8 that is connected to the outlet 2b (the upper end in Figure 6). The downstream end 8b is the end of the auxiliary downpipe 8 that is connected to the first elbow 7a (the lower end in Figure 6).

[0064] In the rain gutter system 10 shown in Figure 6, the downpipe 3 comprises a first vertical pipe 31, a second vertical pipe 32, and a piping member 5. The piping member 5 comprises a straight pipe section 51 and a discharge section 52, similar to Embodiment 1. The presence of the discharge section 52 in the piping member 5 makes it possible to intentionally create a waterlogged area in the downpipe 3 of the rain gutter system 10.

[0065] In the rain gutter system 10 shown in Figure 6, a gap is likely to occur at the location indicated by A1 in the second elbow 7b. In other words, it is difficult for the second elbow 7b to become completely filled with water. However, the discharge section 52 fills the downpipe 3 downstream of the discharge section 52 with water before the downpipe 3 upstream of the discharge section 52. Therefore, the downpipe 3 is less affected by the occurrence of a gap at the location indicated by A1 when it comes to filling the downpipe 3 with water.

[0066] Figure 7 is an explanatory diagram of drainage by the rain gutter system 10. As shown in Figure 7, the piping member 5 can fill the area between the position HP of the discharge section 52 and the position LP of the downstream end 3b in the downpipe 3 with water.

[0067] One factor contributing to the siphon effect is the difference in potential energy between the upper and lower ends of the water surface as viewed from the vertical. The larger the difference in potential energy, the greater the increase in flow velocity due to the siphon effect, which is thought to increase the flow rate. In the case of Figure 7, the longer the vertical length of the area in the downpipe 3 that is filled with water, that is, the longer the distance H1 between the position HP of the discharge section 52 and the position LP of the downstream end 3b in the vertical direction, the greater the negative pressure at the discharge section 52, and the greater the suction force due to the siphon effect. As a result, the piping member 5 can stably promote the effect of the siphon effect.

[0068] The position of the piping member 5 in the downpipe 3 can be appropriately set according to the pipe diameter of the downpipe 3, the amount of rainwater passing through the downpipe 3, the installation environment of the rain gutter system 10, and various other conditions. For example, the position of the piping member 5 in the downpipe 3 may be set so as to obtain a desired difference in potential energy, taking into account the amount of rainwater expected at the installation site of the rain gutter system 10. For example, the position of the piping member 5 in the downpipe 3 may be set so that the distance H1 is a value that obtains a desired difference in potential energy.

[0069] [1.2.2 Effects, etc.] The piping member 5 described above constitutes a part of the downpipe 3 of the rain gutter system 10, which utilizes the siphon effect for rainwater drainage. The piping member 5 comprises a straight pipe section 51 that defines at least a part of the flow path 30 of the downpipe 3, and a discharge section 52 that is connected to the straight pipe section 51 and positioned in the flow path 30. The discharge section 52 has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0070] In the piping member 5, the guide surface 522 approaches the central axis C1 of the straight pipe section 51 as it moves downstream from the opening 521 towards the downpipe 3. This configuration makes it easier to guide rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51, thereby further stably promoting the effect of the siphon phenomenon.

[0071] In the piping member 5, the length of the guide surface 522 in the direction of the central axis C1 of the straight pipe section 51 is set such that the downstream side of the discharge section 52 in the downpipe 3 becomes full of water before the upstream side of the discharge section 52 in the downpipe 3. This configuration can stably promote the effect of the siphon phenomenon.

[0072] In the piping member 5, the edge of the opening 521 is rounded (R-shaped). This configuration reduces losses at the edge of the opening 521.

[0073] In the piping member 5, the center O1 of the opening 521 lies on the central axis C1 of the straight pipe section 51. This configuration allows for stable promotion of the siphon effect.

[0074] The rain gutter system 10 described above includes a downpipe 3 having a piping member 5 and connected to a rainwater outlet 2b from the building 110, and a drain 4 located at the outlet 2b. This configuration can stably promote the action due to the siphon phenomenon.

[0075] The rain gutter system 10 further comprises a connecting pipe 6 located between the downspout 2b and the downpipe 3, a first elbow 7a connecting the upstream end 6a of the connecting pipe 6 to the downspout 2b, and a second elbow 7b connecting the downstream end 6b of the connecting pipe 6 to the upstream end 3a of the downpipe 3. This configuration can stably promote the action due to the siphon phenomenon.

[0076] [2. Variant] The embodiments of this disclosure are not limited to those described above. The embodiments can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure can be achieved. The following lists some modifications of the embodiments. The modifications described below can be combined and applied as appropriate.

[0077] [2.1 Variation 1] Figure 8 is a cross-sectional view of an example configuration of the piping member 5A of Modified Example 1. The piping member 5A in Figure 8 comprises a straight pipe section 51 and a discharge section 52A. The discharge section 52A has a partition wall section 53A and a guide section 54.

[0078] The partition wall 53A extends from the inner surface 510 of the straight pipe section 51 toward the central axis C1 of the straight pipe section 51. The partition wall 53A has an opening 521. The opening 521 is located in the center of the partition wall 53A when viewed from the direction of the central axis C1 of the straight pipe section 51. When viewed from the direction of the central axis C1 of the straight pipe section 51, the partition wall 53A is annular. The dimensions of the partition wall 53A in the direction of the central axis C1 of the straight pipe section 51 become smaller as it moves from the inner surface 510 toward the central axis C1 of the straight pipe section 51. In Figure 8, the surface of the partition wall 53A on the side of the first end 51a of the straight pipe section 51 is a tapered surface 524 inclined with respect to the central axis C1 of the straight pipe section 51. In other words, the tapered surface 524 extends from the inner surface 510 of the straight pipe section 51 toward the opening 521 in a direction that intersects the central axis C1 of the straight pipe section 51 without being perpendicular to it. In Figure 8, the surface on the second end 51b side of the straight pipe section 51 in the partition wall section 53A is a plane perpendicular to the central axis C1 of the straight pipe section 51.

[0079] Thus, in the piping member 5A of Figure 8, the discharge section 52A further has a tapered surface 524 that extends from the inner surface 510 of the straight pipe section 51 toward the opening 521 in a direction that intersects but is not perpendicular to the central axis C1 of the straight pipe section 51. The tapered surface 524 can reduce the pressure loss due to the opening 521 of the discharge section 52A. If the pressure loss due to the opening 521 is too large in the piping member 5 of Figure 3, it is possible to reduce the pressure loss to a desired level by providing a tapered surface 524 as in the piping member 5A of Figure 8. In other words, the pressure loss due to the opening 521 of the discharge section 52A can be adjusted by appropriately setting the angle of the tapered surface 524 with respect to the central axis C1 and the shape of the tapered surface 524.

[0080] In the discharge section 52A shown in Figure 8, the guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52A, with the help of the guide surface 522, converges the rainwater that has passed through the opening 521. The rainwater converged by the discharge section 52A strikes the central air layer of the downpipe 3. As a result, the rainwater actively strikes the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater experiences air resistance, the flow velocity of the rainwater may decrease below the discharge section 52A. Therefore, the space between the discharge section 52A and the downstream end 3b of the downpipe 3 can be filled with water.

[0081] The piping member 5A described above constitutes a part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage. The piping member 5A comprises a straight pipe section 51 that defines at least a part of the flow path of the downpipe, and a discharge section 52A that is connected to the straight pipe section 51 and positioned in the flow path. The discharge section 52A has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0082] In the piping member 5A, the discharge section 52A further has a tapered surface 524 that extends from the inner surface 510 of the straight pipe section 51 toward the opening 521 in a direction that intersects but is not perpendicular to the central axis C1 of the straight pipe section 51. This configuration can reduce pressure loss due to the opening 521.

[0083] Piping member 5A can be applied in place of piping member 5 to the rain gutter system 1 in Figure 1 or the rain gutter system 10 in Figure 6.

[0084] [2.2 Variation 2] Figure 9 is a cross-sectional view of an example configuration of the piping member 5B of Modification 2. The piping member 5B in Figure 9 comprises a straight pipe section 51 and a discharge section 52B. The discharge section 52B has a partition wall section 53 and a guide section 54, similar to the discharge section 52, but its position relative to the straight pipe section 51 is different from that of the discharge section 52.

[0085] In Figure 9, the discharge section 52B is connected to the straight pipe section 51 and positioned in the flow path 30. In this modified example, as shown in Figure 9, the discharge section 52B is located in the intermediate section 51c of the straight pipe section 51. In this modified example, the discharge section 52B is formed integrally with the straight pipe section 51 and is therefore connected to the straight pipe section 51.

[0086] In the piping member 5B shown in Figure 9, the straight pipe section 51 has an opening 511 at the first end 51a and an opening 512 at the second end 51b. In this modified example, the opening 511 defines the inlet of the piping member 5B. In this modified example, the opening 512 of the straight pipe section 51, rather than the opening 523 of the discharge section 52B, defines the outlet of the piping member 5B.

[0087] In the discharge section 52B shown in Figure 9, the guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52B, with the help of the guide surface 522, concentrates the rainwater that has passed through the opening 521. The rainwater diffused by the discharge section 52B strikes the air layer in the center of the downpipe 3. As a result, the rainwater actively strikes the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater experiences air resistance, the flow velocity of the rainwater may decrease below the discharge section 52B. Therefore, the space between the discharge section 52B and the downstream end 3b of the downpipe 3 can be filled with water.

[0088] The piping member 5B described above constitutes a part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage. The piping member 5B comprises a straight pipe section 51 that defines at least a part of the flow path of the downpipe, and a discharge section 52B that is connected to the straight pipe section 51 and positioned in the flow path. The discharge section 52B has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0089] Piping member 5B can be applied in place of piping member 5 to the rain gutter system 1 in Figure 1 or the rain gutter system 10 in Figure 6.

[0090] [2.3 Variation 3] Figure 10 is a cross-sectional view of an example configuration of the piping member 5C of Modification 3. The piping member 5C in Figure 10 comprises a straight pipe section 51 and a discharge section 52C. The discharge section 52C is located in the middle section 51c of the straight pipe section 51, similar to the discharge section 52B, but its shape is different from that of the discharge section 52B.

[0091] The discharge section 52C is connected to the straight pipe section 51 and positioned in the flow path 30. As shown in Figure 10, the discharge section 52C is located in the middle section 51c of the straight pipe section 51. The discharge section 52C is formed integrally with the straight pipe section 51 and is therefore connected to the straight pipe section 51.

[0092] The discharge section 52C extends from the inner surface 510 of the straight pipe section 51 toward the central axis C1 of the straight pipe section 51. The discharge section 52C is a plate-like structure with a uniform thickness. The discharge section 52C has a through hole 525. The through hole 525 has an opening 521 on the first end 51a side of the straight pipe section 51 and an opening 523 on the second end 51b side of the straight pipe section 51. The inner circumferential shape of the through hole 525 in a plane perpendicular to the central axis C1 of the straight pipe section 51 becomes smaller from the opening 521 toward the opening 523. As a result, the inner surface of the through hole 525 includes a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51.

[0093] In this modified example, the through-hole 525 is located in the center of the discharge section 52C when viewed from the direction of the central axis C1 of the straight pipe section 51. The through-hole 525 is circular when viewed from the direction of the central axis C1 of the straight pipe section 51. The through-hole 525 includes a portion where the inner diameter decreases from the opening 521 to the opening 523. As a result, the inner surface of the through-hole 525 includes the guide surface 522. In this modified example, the inner diameter D2 of the opening 521 is smaller than the inner diameter D1 of the straight pipe section 51. The inner diameter D3 of the opening 523 is smaller than the inner diameter D2 of the opening 521. In this modified example, the edge of the opening 521 is rounded (R-shaped).

[0094] Furthermore, the discharge section 52C of the piping member 5C in Figure 10 can be said to have a shape in which the gap between the guide section 54 and the inner surface 510 of the straight pipe section 51 is filled, compared to the discharge section 52B of the piping member 5B in Figure 9.

[0095] In the piping member 5C of Figure 10, the straight pipe section 51 has an opening 511 at the first end 51a and an opening 512 at the second end 51b. In this modified example, the opening 511 defines the inlet of the piping member 5C, and the opening 512 defines the outlet of the piping member 5C.

[0096] In the discharge section 52C of Figure 10, the guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52C, with the help of the guide surface 522, concentrates the rainwater that has passed through the opening 521. The rainwater diffused by the discharge section 52C strikes the air layer in the center of the downpipe 3. As a result, the rainwater actively strikes the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater experiences air resistance, the flow velocity of the rainwater may decrease below the discharge section 52C. Therefore, the space between the discharge section 52C and the downstream end 3b of the downpipe 3 can be filled with water.

[0097] The piping member 5C described above constitutes a part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage. The piping member 5C comprises a straight pipe section 51 that defines at least a part of the flow path of the downpipe, and a discharge section 52C that is connected to the straight pipe section 51 and positioned in the flow path. The discharge section 52C has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0098] Piping member 5C can be applied in place of piping member 5 to the rain gutter system 1 in Figure 1 or the rain gutter system 10 in Figure 6.

[0099] [2.4 Modification 4] Figure 11 is a cross-sectional view of an example configuration of the piping member 5D of Modification 4. The piping member 5D in Figure 11 comprises a straight pipe section 51 and a discharge section 52D. The discharge section 52D has a partition wall section 53 and a guide section 54, similar to the discharge section 52, but its position relative to the straight pipe section 51 is different from that of the discharge section 52.

[0100] In Figure 11, the discharge section 52D is connected to the straight pipe section 51 and positioned in the flow path 30. In this modified example, as shown in Figure 11, the discharge section 52D is located at the first end 51a of the straight pipe section 51. In this modified example, the discharge section 52D is formed integrally with the straight pipe section 51 and is therefore connected to the straight pipe section 51.

[0101] In the piping member 5D shown in Figure 11, the opening 521 of the discharge section 52D defines the inlet of the piping member 5D. In the piping member 5D shown in Figure 11, the straight pipe section 51 has an opening 512 at the second end 51b. In this modified example, the opening 512 of the straight pipe section 51, rather than the opening 523 of the discharge section 52D, defines the outlet of the piping member 5D.

[0102] In the discharge section 52D shown in Figure 11, the guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52D, with the help of the guide surface 522, converges the rainwater that has passed through the opening 521. The rainwater converged by the discharge section 52D strikes the central air layer of the downpipe 3. As a result, the rainwater actively strikes the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater experiences air resistance, the flow velocity of the rainwater may decrease below the discharge section 52D. Therefore, the space between the discharge section 52D and the downstream end 3b of the downpipe 3 can be filled with water.

[0103] The piping member 5D described above constitutes a part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage. The piping member 5D comprises a straight pipe section 51 that defines at least a portion of the flow path of the downpipe, and a discharge section 52D that is connected to the straight pipe section 51 and positioned in the flow path. The discharge section 52D has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0104] Piping member 5D can be applied in place of piping member 5 to the rain gutter system 1 in Figure 1 or the rain gutter system 10 in Figure 6.

[0105] [2.5 Variation 5] Figure 12 is a cross-sectional view of an example configuration of the piping member 5E of modified example 5. The piping member 5E in Figure 12 comprises a straight pipe section 51 and a discharge section 52E.

[0106] The discharge section 52E is connected to the straight pipe section 51 and positioned in the flow path 30. As shown in Figure 12, the discharge section 52E is located at the second end 51b of the straight pipe section 51. The discharge section 52E is formed integrally with the straight pipe section 51 and is therefore connected to the straight pipe section 51.

[0107] As shown in Figure 12, the discharge section 52E includes a partition wall section 53E and a guide section 54E.

[0108] The partition wall 53E extends from the inner surface 510 of the straight pipe section 51 toward the central axis C1 of the straight pipe section 51. The partition wall 53E is a plate-like structure with uniform thickness. The partition wall 53E has an opening 523. As a result, the opening 523 is located inside the straight pipe section 51. That is, the discharge section 52E is connected to the straight pipe section 51 such that the opening 523 is located inside the straight pipe section 51. The opening 523 is in the center of the partition wall 53E when viewed from the direction of the central axis C1 of the straight pipe section 51. When viewed from the direction of the central axis C1 of the straight pipe section 51, the partition wall 53E is annular. The flow area of ​​the opening 523 is smaller than that of the straight pipe section 51. In a plane perpendicular to the central axis C1 of the straight pipe section 51, the opening 523 is circular. The inner diameter D3 of the opening 523 is smaller than the inner diameter D1 of the straight pipe section 51.

[0109] The guide portion 54E protrudes from the edge of the opening 523 of the partition wall portion 53E toward the upstream side of the downpipe 3, for example, toward the second end 51b of the straight pipe portion 51 toward the first end 51a. The guide portion 54E surrounds the entire circumference of the opening 523. The guide portion 54E has an opening 521 on the opposite side of the guide portion 54E from the opening 523. The inner diameter D2 of the opening 521 is smaller than the inner diameter D1 of the straight pipe portion 51, but larger than the inner diameter D3 of the opening 523.

[0110] The guide portion 54E is hollow and frustoconical. In this modified example, the guide portion 54E is hollow and frustoconical. The outer and inner circumferential shapes of the guide portion 54E in the plane perpendicular to the central axis C1 of the straight pipe portion 51 are circular. The outer and inner circumferential shapes of the guide portion 54E in the plane perpendicular to the central axis C1 of the straight pipe portion 51 increase from the second end 51b to the first end 51a of the straight pipe portion 51.

[0111] In this modified example, the inner circumferential surface of the guide portion 54E functions as a guide surface 522 for rainwater passing through the opening 521. The guide surface 522 faces inward towards the straight pipe portion 51. The guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe portion 51. The guide surface 522 approaches the central axis C1 of the straight pipe portion 51 as it moves downstream from the opening 521 towards the downpipe 3. In this modified example, the inclination of the guide surface 522 is constant. That is, the increment of the distance between the guide surface 522 and the central axis C1 in the plane perpendicular to the central axis C1 of the straight pipe portion 51, relative to the distance from the opening 521, is constant.

[0112] In the piping member 5E shown in Figure 12, the opening 511 of the straight pipe section 51 defines the inlet of the piping member 5E. In the piping member 5E shown in Figure 12, the opening 523 of the discharge section 52E defines the outlet of the piping member 5E.

[0113] In the discharge section 52E shown in Figure 12, the guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52E, with the help of the guide surface 522, concentrates the rainwater that has passed through the opening 521. The rainwater diffused by the discharge section 52E strikes the air layer in the center of the downpipe 3. As a result, the rainwater actively strikes the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater experiences air resistance, the flow velocity of the rainwater may decrease below the discharge section 52E. Therefore, the space between the discharge section 52E and the downstream end 3b of the downpipe 3 can be filled with water.

[0114] The piping member 5E described above constitutes a part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage. The piping member 5E comprises a straight pipe section 51 that defines at least a part of the flow path of the downpipe, and a discharge section 52E that is connected to the straight pipe section 51 and positioned in the flow path. The discharge section 52E has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0115] Piping member 5E can be applied in place of piping member 5 to the rain gutter system 1 in Figure 1 or the rain gutter system 10 in Figure 6.

[0116] [2.6 Variation 6] Figure 13 is a cross-sectional view of an example configuration of the piping member 5F of modified example 6. The piping member 5F in Figure 13 comprises a straight pipe section 51 and a discharge section 52F.

[0117] The discharge section 52F is connected to the straight pipe section 51 and positioned in the flow path 30. As shown in Figure 13, the discharge section 52F extends across the intermediate section 51c and the second end section 51b of the straight pipe section 51. The discharge section 52F is formed integrally with the straight pipe section 51 and is therefore connected to the straight pipe section 51.

[0118] The discharge section 52F in Figure 13 defines an internal flow path 526 connected to the space enclosed by the inner surface 510 of the straight pipe section 51. The internal flow path 526 includes a first constriction flow path 526a and a second constriction flow path 526b. The first constriction flow path 526a and the second constriction flow path 526b are arranged in this order in the direction from the first end 51a to the second end 51b of the straight pipe section 51. The boundary between the first constriction flow path 526a and the second constriction flow path 526b defines an opening 521 with a flow path area smaller than that of the straight pipe section 51. In Figure 13, the inclination of the inner surface of the second constriction flow path 526b is smaller than the inclination of the inner surface of the first constriction flow path 526a. The inclination of the inner surface of the second constriction flow path 526b may be greater than or the same as the inclination of the inner surface of the first constriction flow path 526a.

[0119] The flow area of ​​the first narrowing channel 526a decreases from the first end 51a to the second end 51b of the straight pipe section 51. In other words, the inner circumferential shape of the first narrowing channel 526a in a plane perpendicular to the central axis C1 of the straight pipe section 51 decreases from the first end 51a to the opening 521. As a result, the inner surface of the first narrowing channel 526a defines a tapered surface 524 that extends from the inner surface 510 of the straight pipe section 51 toward the opening 521 in a direction that does not perpendicular to the central axis C1 of the straight pipe section 51 but intersects it. The first narrowing channel 526a connects to the space enclosed by the inner surface 510 of the straight pipe section 51 on the opposite side of the opening 521.

[0120] The flow area of ​​the second narrowing channel 526b decreases from the first end 51a to the second end 51b of the straight pipe section 51. In other words, the inner circumferential shape of the second narrowing channel 526b in a plane perpendicular to the central axis C1 of the straight pipe section 51 decreases from the opening 521 to the second end 51b. This defines a guide surface 522 on the inner surface of the second narrowing channel 526b that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. The second narrowing channel 526b has an opening 523 on the opposite side of the opening 521.

[0121] In this modified example, the central axis C2 of the internal flow path 526 coincides with the central axis C1 of the straight pipe section 51. The internal flow path 526 is circular when viewed from the direction of the central axis C1 of the straight pipe section 51. In this modified example, the inner diameter D2 of the opening 521 is smaller than the inner diameter D1 of the straight pipe section 51. The inner diameter D3 of the opening 523 is smaller than the inner diameter D2 of the opening 521.

[0122] In the piping member 5F shown in Figure 13, the straight pipe section 51 has an opening 511 at its first end 51a, and the discharge section 52F has an opening 523. In this modified example, the opening 511 defines the inlet of the piping member 5F. In this modified example, the opening 523 of the discharge section 52F defines the outlet of the piping member 5F.

[0123] In the discharge section 52F shown in Figure 13, the guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52F, with the help of the guide surface 522, converges the rainwater that has passed through the opening 521. The rainwater converged by the discharge section 52F strikes the air layer in the center of the downpipe 3. As a result, the rainwater actively strikes the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater experiences air resistance, the flow velocity of the rainwater may decrease below the discharge section 52F. Therefore, the space between the discharge section 52F and the downstream end 3b of the downpipe 3 can be filled with water.

[0124] The piping member 5F described above constitutes a part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage. The piping member 5F comprises a straight pipe section 51 that defines at least a part of the flow path of the downpipe, and a discharge section 52F that is connected to the straight pipe section 51 and positioned in the flow path. The discharge section 52F has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0125] In the piping member 5F, the discharge section 52F further has a tapered surface 524 that extends from the inner surface 510 of the straight pipe section 51 toward the opening 521 in a direction that intersects but is not perpendicular to the central axis C1 of the straight pipe section 51. This configuration can reduce pressure loss due to the opening 521.

[0126] The piping member 5F can be applied to the rain gutter system 1 in Figure 1 or the rain gutter system 10 in Figure 6, instead of the piping member 5.

[0127] [2.7 Variation 7] Figure 14 is a cross-sectional view of an example configuration of the piping member 5G in modified example 7. The piping member 5G in Figure 14 comprises a straight pipe section 51 and a discharge section 52G.

[0128] The discharge section 52G is connected to the straight pipe section 51 and positioned in the flow path 30. As shown in Figure 14, the discharge section 52G extends across the intermediate section 51c and the second end section 51b of the straight pipe section 51. The discharge section 52G is formed integrally with the straight pipe section 51 and is therefore connected to the straight pipe section 51.

[0129] The discharge section 52G in Figure 14 defines an internal flow path 526, similar to the discharge section 52F in Figure 13. As described above, the internal flow path 526 defines an opening 521, a guide surface 522, and a tapered surface 524.

[0130] In the discharge section 52G, the corner B1 between the inner surface 510 of the straight pipe section 51 and the tapered surface 524 is rounded (R-shaped). This reduces the generation of turbulence at the corner B1 between the inner surface 510 of the straight pipe section 51 and the tapered surface 524. The degree of the rounded shape of corner B1 can be appropriately set according to the pipe diameter of the downpipe 3, the amount of rainwater passing through the downpipe 3, the installation environment of the rain gutter system 1, and various other conditions.

[0131] In the discharge section 52G, the corner B2 between the tapered surface 524 and the guide surface 522 is rounded (R-shaped). Corner B2 corresponds to the edge of the opening 521. In other words, in the discharge section 52G, the edge of the opening 521 is rounded (R-shaped). This reduces losses at the edge of the opening 521. The degree of the rounded shape of corner B2 can be appropriately set according to the pipe diameter of the downpipe 3, the amount of rainwater passing through the downpipe 3, the installation environment of the rain gutter system 1, and various other conditions.

[0132] In the piping member 5G shown in Figure 14, the straight pipe section 51 has an opening 511 at its first end 51a, and the discharge section 52G has an opening 523. In this modified example, the opening 511 defines the inlet of the piping member 5G. In this modified example, the opening 523 of the discharge section 52G defines the outlet of the piping member 5G.

[0133] In the discharge section 52G shown in Figure 14, the guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52G, with the help of the guide surface 522, converges the rainwater that has passed through the opening 521. The rainwater converged by the discharge section 52G strikes the air layer in the center of the downpipe 3. As a result, the rainwater actively strikes the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater experiences air resistance, the flow velocity of the rainwater may decrease below the discharge section 52G. Therefore, the space between the discharge section 52G and the downstream end 3b of the downpipe 3 can be filled with water.

[0134] The piping member 5G described above constitutes a part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage. The piping member 5G comprises a straight pipe section 51 that defines at least a part of the flow path of the downpipe, and a discharge section 52G that is connected to the straight pipe section 51 and positioned in the flow path. The discharge section 52G has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0135] In the piping member 5G, the discharge section 52G further has a tapered surface 524 that extends from the inner surface 510 of the straight pipe section 51 toward the opening 521 in a direction that intersects but is not perpendicular to the central axis C1 of the straight pipe section 51. This configuration can reduce pressure loss due to the opening 521.

[0136] In the piping member 5G, the corner B1 between the inner surface 510 of the straight pipe section 51 and the tapered surface 524 is rounded (R-shaped). This configuration reduces the generation of turbulence at the corner B1 between the inner surface 510 of the straight pipe section 51 and the tapered surface 524.

[0137] In the piping member 5G, the edge of the opening 521 (the corner B2 between the tapered surface 524 and the guide surface 522) is rounded (R-shaped). This configuration reduces losses at the edge of the opening 521.

[0138] Piping member 5G can be applied in place of piping member 5 to the rain gutter system 1 in Figure 1 or the rain gutter system 10 in Figure 6.

[0139] [2.8 Variation 8] Figure 15 is a cross-sectional view of an example configuration of the piping member 5H in modified example 8. The piping member 5H in Figure 15 can be applied to the rain gutter system 1 in Figure 1 instead of the piping member 5.

[0140] The piping member 5H in Figure 15 comprises a straight pipe section 51 and a discharge section 52H.

[0141] The discharge section 52H is connected to the straight pipe section 51 and positioned in the flow path 30. As shown in Figure 15, the discharge section 52H is located at the second end 51b of the straight pipe section 51. The discharge section 52H is formed integrally with the straight pipe section 51 and is therefore connected to the straight pipe section 51.

[0142] The discharge section 52H extends from the inner surface 510 of the straight pipe section 51 toward the central axis C1 of the straight pipe section 51. The discharge section 52H is a plate-like structure with a uniform thickness. The discharge section 52H has a through hole 527. The through hole 527 has an opening 521 on the first end 51a side of the straight pipe section 51 and an opening 523 on the second end 51b side of the straight pipe section 51. The inner circumferential shape of the through hole 527 in a plane perpendicular to the central axis C1 of the straight pipe section 51 becomes smaller from the opening 521 toward the opening 523.

[0143] In the discharge section 52H, the length of the through-hole 527 is set such that the inner surface of the through-hole 527 functions as a guide surface 522, relative to the flow path area of ​​the through-hole 527. Here, the flow path area of ​​the through-hole 527 is the cross-sectional area of ​​the through-hole in a plane perpendicular to the central axis C1 of the straight pipe section 51. The flow path area of ​​the through-hole 527 is equal to the flow path area of ​​the opening 521. The length of the through-hole 527 is the dimension of the through-hole 527 in the direction of the central axis C1 of the straight pipe section 51. In particular, if the effect of turbulence is small in the rainwater flowing through the flow path 30 of the downpipe 3, the length of the through-hole 527 can be shortened. In Figure 15, the length of the guide surface 522 in the direction of the central axis C1 of the straight pipe section 51 can be made to match the thickness of the discharge section 52I. The discharge section 52H in Figure 15 can be formed by providing a through-hole in a plate-like portion, and has a simpler shape than, for example, the discharge section 52 in Figure 3. Therefore, the manufacturing of the piping member 5H becomes easier.

[0144] In this modified example, the through-hole 527 is located in the center of the discharge section 52H. The through-hole 527 is circular when viewed from the direction of the central axis C1 of the straight pipe section 51. In this modified example, the inner diameter D2 of the opening 521 is smaller than the inner diameter D1 of the straight pipe section 51. The inner diameter D3 of the opening 523 is smaller than the inner diameter D2 of the opening 521.

[0145] In the piping member 5H shown in Figure 15, the straight pipe section 51 has an opening 511 at its first end 51a, and the discharge section 52H has an opening 523. In this modified example, the opening 511 defines the inlet of the piping member 5H, and the opening 523 defines the outlet of the piping member 5H.

[0146] In the discharge section 52H shown in Figure 15, the guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52H, with the help of the guide surface 522, concentrates the rainwater that has passed through the opening 521. The rainwater diffused by the discharge section 52H strikes the air layer in the center of the downpipe 3. As a result, the rainwater actively strikes the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater experiences air resistance, the flow velocity of the rainwater may decrease below the discharge section 52H. Therefore, the space between the discharge section 52H and the downstream end 3b of the downpipe 3 can be filled with water.

[0147] In particular, piping member 5H is applied to the rain gutter system 1 in Figure 1 instead of piping member 5. In the rain gutter system 1 in Figure 1, unlike the rain gutter system 10 in Figure 6, when the siphon effect is not occurring, the flow of rainwater generally falls from the outlet 2b along the pipe wall of the downpipe 3 to the discharge section 52I of piping member 5H. As the amount of rainfall increases, rainwater accumulates above the discharge section 52H of piping member 5H, and the rainwater above the discharge section 52H increases in flow velocity through the opening 521, which has a smaller flow path area than the straight pipe section 51, and is discharged downward from the discharge section 52H along the guide surface 522. Therefore, the guide surface 522 of the discharge section 52H can utilize the energy of the rainwater itself to guide the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51.

[0148] The piping member 5H described above constitutes a part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage. The piping member 5H comprises a straight pipe section 51 that defines at least a part of the flow path of the downpipe, and a discharge section 52H that is connected to the straight pipe section 51 and positioned in the flow path. The discharge section 52H has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0149] [2.9 Modification 9] Figure 16 is a cross-sectional view of an example configuration of the piping member 5I in modified example 9. The piping member 5I in Figure 16 can be applied to the rain gutter system 1 in Figure 1 instead of the piping member 5.

[0150] The piping member 5I in Figure 16 comprises a straight pipe section 51 and a discharge section 52I.

[0151] The discharge section 52I is connected to the straight pipe section 51 and positioned in the flow path 30. As shown in Figure 16, the discharge section 52I extends across the intermediate section 51c and the second end section 51b of the straight pipe section 51. The discharge section 52I is formed integrally with the straight pipe section 51 and is therefore connected to the straight pipe section 51.

[0152] The discharge section 52I in Figure 16 defines an internal flow path 55 connected to the space enclosed by the inner surface 510 of the straight pipe section 51. The internal flow path 55 includes a first constriction flow path 55a, a connecting flow path 55b, and a second constriction flow path 55c. The first constriction flow path 55a, the connecting flow path 55b, and the second constriction flow path 55c are arranged in this order in the direction from the first end 51a to the second end 51b of the straight pipe section 51. In Figure 16, the inclination of the inner surface of the second constriction flow path 55c is smaller than the inclination of the inner surface of the first constriction flow path 55a. The inclination of the inner surface of the second constriction flow path 55c may be larger than or the same as the inclination of the inner surface of the first constriction flow path 55a.

[0153] The flow area of ​​the first narrowing channel 55a decreases from the first end 51a to the second end 51b of the straight pipe section 51. In other words, the inner circumferential shape of the first narrowing channel 55a in a plane perpendicular to the central axis C1 of the straight pipe section 51 decreases from the first end 51a to the second end 51b. As a result, the inner surface of the first narrowing channel 55a defines a tapered surface 524 that extends from the inner surface 510 of the straight pipe section 51 toward the opening 521 in a direction that does not perpendicular to the central axis C1 of the straight pipe section 51 but intersects it. The first narrowing channel 55a connects to the space enclosed by the inner surface 510 of the straight pipe section 51 on the opposite side of the opening 521.

[0154] The flow area of ​​the connecting flow channel 55b does not change from the first end 51a to the second end 51b of the straight pipe section 51. In other words, the inner circumferential shape of the connecting flow channel 55b in a plane perpendicular to the central axis C1 of the straight pipe section 51 is constant. At the discharge section 52I, the connecting flow channel 55b defines an opening 521 with a smaller flow area than that of the straight pipe section 51.

[0155] The flow area of ​​the second narrowing channel 55c decreases from the first end 51a to the second end 51b of the straight pipe section 51. In other words, the inner circumferential shape of the second narrowing channel 55c in a plane perpendicular to the central axis C1 of the straight pipe section 51 decreases from the first end 51a to the second end 51b. The inner surface of the second narrowing channel 55c defines a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. The second narrowing channel 55c has an opening 523 on the opposite side of the opening 521.

[0156] In this modified example, the central axis C3 of the internal flow path 55 coincides with the central axis C1 of the straight pipe section 51. The internal flow path 55 is circular when viewed from the direction of the central axis C1 of the straight pipe section 51. In this modified example, the inner diameter D2 of the opening 521 is smaller than the inner diameter D1 of the straight pipe section 51. The inner diameter D3 of the opening 523 is smaller than the inner diameter D2 of the opening 521.

[0157] In the piping member 5I shown in Figure 16, the straight pipe section 51 has an opening 511 at its first end 51a, and the discharge section 52I has an opening 523. In this modified example, the opening 511 defines the inlet of the piping member 5I. In this modified example, the opening 523 of the discharge section 52I defines the outlet of the piping member 5I.

[0158] In the discharge section 52I shown in Figure 16, the guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52I, with the help of the guide surface 522, converges the rainwater that has passed through the opening 521. The rainwater converged by the discharge section 52I strikes the central air layer of the downpipe 3. As a result, the rainwater actively strikes the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater experiences air resistance, the flow velocity of the rainwater may decrease below the discharge section 52I. Therefore, the space between the discharge section 52I and the downstream end 3b of the downpipe 3 can be filled with water.

[0159] In particular, the piping member 5I is applied to the rain gutter system 1 in Figure 1 instead of the piping member 5. In the rain gutter system 1 in Figure 1, unlike the rain gutter system 10 in Figure 6, when the siphon effect is not occurring, the flow of rainwater generally falls from the outlet 2b along the pipe wall of the downpipe 3 to the discharge section 52I of the piping member 5I. As the amount of rainfall increases, rainwater accumulates above the discharge section 52I of the piping member 5I, and the rainwater above the discharge section 52I increases in flow velocity through the opening 521, which has a smaller flow path area than the straight pipe section 51, and is discharged downward from the discharge section 52I along the guide surface 522. Therefore, the guide surface 522 of the discharge section 52I can use the energy of the rainwater itself to guide the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51.

[0160] The piping member 5I described above constitutes a part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage. The piping member 5I comprises a straight pipe section 51 that defines at least a part of the flow path of the downpipe, and a discharge section 52I that is connected to the straight pipe section 51 and positioned in the flow path. The discharge section 52I has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0161] In the piping member 5I, the guide surface 522 approaches the central axis C1 of the straight pipe section 51 as it moves downstream from the opening 521 towards the downpipe 3. This configuration makes it easier to guide rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51, thereby further stably promoting the effect of the siphon phenomenon.

[0162] In the piping member 5I, the discharge section 52I further has a tapered surface 524 that extends from the inner surface 510 of the straight pipe section 51 toward the opening 521 in a direction that intersects but is not perpendicular to the central axis C1 of the straight pipe section 51. This configuration can reduce pressure loss due to the opening 521.

[0163] [2.10 Variation 10] Figure 17 is a schematic diagram of an example configuration of a rain gutter system 1J equipped with a piping member 5J of modified example 10. The rain gutter system 1J in Figure 17 comprises a gutter 2, a downpipe 3J, and a drain 4.

[0164] The downpipe 3J in Figure 17 comprises a first vertical pipe 31, a second vertical pipe 32, a piping member 5J, a first socket 35a, and a second socket 35b.

[0165] The piping member 5J constitutes part of the downpipe 3J of the rain gutter system 1J, which utilizes the siphon effect for rainwater drainage. The piping member 5J is provided in the rain gutter system 1J to stably promote the action of the siphon effect. In the downpipe 3J shown in Figure 17, the piping member 5J is located between the first vertical pipe 31 and the second vertical pipe 32. The piping member 5J in Figure 17 may be a vertical pipe similar to the first vertical pipe 31 and the second vertical pipe 32. The position of the piping member 5J in the downpipe 3J is set appropriately considering the degree to which the siphon effect occurs during rainwater drainage.

[0166] The piping member 5J comprises a straight pipe section 51J and a discharge section 52.

[0167] The straight pipe section 51J defines at least a portion of the flow path 30 of the downpipe 3J. In this modified example, the internal space of the straight pipe section 51J, surrounded by the inner surface 510 of the straight pipe section 51J, becomes part of the flow path 30 of the downpipe 3J. The cross-section of the straight pipe section 51J perpendicular to the central axis C1 is circular. The central axis C1 of the straight pipe section 51J is also the pipe axis of the straight pipe section 51J. The material of the straight pipe section 51J is rigid polyvinyl chloride. The dimensions of the straight pipe section 51J, for example, the outer shape and thickness, may be set in accordance with the standard for rigid polyvinyl chloride pipes (general) of JIS K 6741 "Rigid Polyvinyl Chloride Pipe". The straight pipe section 51J is positioned such that the direction of the central axis C1 of the straight pipe section 51J coincides with the vertical direction.

[0168] In this modified example, the dimensions of the straight pipe section 51J are the same as at least one of the first vertical pipe 31 and the second vertical pipe 32 used in the downpipe 3J. Therefore, the straight pipe section 51J has a mark 51e on its outer surface to distinguish it from the vertical pipes (first vertical pipe 31 and / or the second vertical pipe 32) used in the downpipe 3J that have the same dimensions as the straight pipe section 51J. This allows the piping member 5J to be distinguished from the first vertical pipe 31 or the second vertical pipe 32, thereby improving the workability of the downpipe 3J. The mark 51e may be a letter, figure, symbol, three-dimensional shape, or color, or a combination thereof, that is recognizable by human perception.

[0169] In Figure 17, mark 51e has the function of indicating the orientation of the piping member 5J during installation. Mark 51e in Figure 17 is an arrow, and when installing the piping member 5J, the piping member 5J should be installed so that the arrow indicated by mark 51e points upward. In Figure 17, mark 51e is exposed in the downpipe 3J, but mark 51e may be placed on the outer surface of the first end 51a or the second end 51b of the straight pipe section 51J, and after construction, mark 51e may be hidden by other members.

[0170] The first socket 35a connects the first vertical pipe 31 to the piping member 5J. In Figure 17, the first socket 35a connects the downstream end of the first vertical pipe 31 to the upstream end (first end 51a) of the piping member 5J. The second socket 35b connects the second vertical pipe 32 to the piping member 5J. In Figure 17, the second socket 35b connects the upstream end of the second vertical pipe 32 to the downstream end (second end 51b) of the piping member 5J. The dimensions of the first socket 35a and the second socket 35b may be set, for example, in accordance with the JIS K 6739 standard "Rigid polyvinyl chloride pipe fittings for drainage".

[0171] As described above, the piping member 5J has a discharge section 52, and the guide surface 522 of the discharge section 52 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52, by its guide surface 522, concentrates the rainwater that has passed through the opening 521. The rainwater diffused by the discharge section 52 hits the air layer in the center of the downpipe 3J. As a result, the rainwater actively collides with the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater experiences air resistance, the flow velocity of the rainwater may decrease below the discharge section 52. Therefore, the space between the discharge section 52 and the downstream end 3b of the downpipe 3 can be filled with water.

[0172] The piping member 5J described above constitutes a part of the downpipe 3J of the rain gutter system 1J that utilizes the siphon effect for rainwater drainage. The piping member 5J comprises a straight pipe section 51J that defines at least a part of the flow path 30 of the downpipe 3J, and a discharge section 52 that is connected to the straight pipe section 51J and positioned in the flow path. The discharge section 52 has an opening 521 with a flow path area smaller than that of the straight pipe section 51J, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51J. This configuration can stably promote the effect of the siphon effect.

[0173] [2.11 Variation 11] Figure 18 is a cross-sectional view of an example configuration of the piping member 5K of modified example 11. The piping member 5K in Figure 18 comprises a straight pipe section 51 and a discharge section 52K.

[0174] The discharge section 52K is connected to the straight pipe section 51 and positioned in the flow path 30. As shown in Figure 18, the discharge section 52K is located at the second end 51b of the straight pipe section 51. The discharge section 52K is formed integrally with the straight pipe section 51 and is therefore connected to the straight pipe section 51.

[0175] The discharge section 52K includes a partition wall section 53 and a guide section 54K.

[0176] The guide portion 54K protrudes from the edge of the opening 521 of the partition wall portion 53 toward the downstream side of the downpipe 3, for example, toward the second end 51b of the straight pipe portion 51 from the first end 51a. The guide portion 54K surrounds the entire circumference of the opening 521. In this modified example, the guide portion 54 is cylindrical. In particular, the guide portion 54K is cylindrical. The outer and inner circumferential shapes of the guide portion 54K in a plane perpendicular to the central axis C1 of the straight pipe portion 51 are circular. The outer and inner circumferential shapes of the guide portion 54 in a plane perpendicular to the central axis C1 of the straight pipe portion 51 do not change toward the second end 51b of the straight pipe portion 51 from the first end 51a.

[0177] In this modified example, the inner circumferential surface of the guide section 54K functions as a guide surface 522 for rainwater passing through the opening 521. The guide surface 522 faces inward towards the straight pipe section 51. The guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. In this modified example, the distance between the guide surface 522 and the central axis C1 of the straight pipe section 51 does not change in the direction of the central axis C1 of the straight pipe section 51. The discharge section 52K in Figure 18 differs from the discharge section 52 in Figure 3 in that the guide surface 522 is not inclined with respect to the central axis C1 of the straight pipe section 51. In the discharge section 52 of Figure 3, even if the amount of rainfall is relatively large and the space between the piping member 5 and the outlet 2b is full or nearly full (even if air bubbles are mixed in), the guide surface 522 can guide the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. In contrast, in the discharge section 52K of Figure 18, when the amount of rainfall is relatively small and the space between the piping member 5 and the outlet 2b is not yet full (or nearly full), the guide surface 522 can guide the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. In other words, in such cases, the rainwater falls along the pipe wall of the downpipe 3 to the discharge section 52K of the piping member 5K and then flows from the pipe wall of the downpipe 3 toward the opening 521. Therefore, even if the guide surface 522 is not inclined with respect to the central axis C1 of the straight pipe section 51, the effect of converging the rainwater can be obtained by the guide surface 522. The guide surface 522 only needs to be able to guide the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51 when the space between the piping member 5 and the outlet 2b is not full (or nearly full).

[0178] The discharge section 52K has an opening 523 on the opposite side of the opening 521 in the guide section 54K. The opening 523 defines the outlet of the piping member 5K. Therefore, in the downpipe 3, rainwater from the piping member 5K enters the second vertical pipe 32 through the opening 523, which is the outlet of the piping member 5K. In this modified example, the inner diameter of the opening 523 is equal to the inner diameter D2 of the opening 521, and is therefore smaller than the inner diameter D1 of the straight pipe section 51.

[0179] In the discharge section 52K shown in Figure 18, the guide surface 522 guides the rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. Therefore, the discharge section 52K, with the help of the guide surface 522, converges the rainwater that has passed through the opening 521. The rainwater converged by the discharge section 52K strikes the air layer in the center of the downpipe 3. As a result, the rainwater actively strikes the air layer, pushing the air out of the downpipe 3 and reducing the amount of air in the downpipe 3. Furthermore, because the rainwater experiences air resistance, the flow velocity of the rainwater may decrease below the discharge section 52K. Therefore, the space between the discharge section 52K and the downstream end 3b of the downpipe 3 can be filled with water.

[0180] The piping member 5K described above constitutes a part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage. The piping member 5K comprises a straight pipe section 51 that defines at least a part of the flow path of the downpipe, and a discharge section 52K that is connected to the straight pipe section 51 and positioned in the flow path. The discharge section 52K has an opening 521 with a flow path area smaller than that of the straight pipe section 51, and a guide surface 522 that guides rainwater passing through the opening 521 toward the central axis C1 of the straight pipe section 51. This configuration can stably promote the effect of the siphon effect.

[0181] [2.13 Other variations] In one modified example, the shape and size of part or all of the discharge section may differ from those of the above embodiment and modified example. For example, unlike the above embodiment, the guide section of the discharge section may be a hollow truncated pyramidal shape. The shape of the straight pipe section and the discharge section in a plane perpendicular to the central axis of the straight pipe section may be polygonal rather than circular. In the above embodiment, the guide surface is linear in the cross-section of the discharge section in a plane containing the central axis of the straight pipe section, but in the modified example, it may be curved or folded.

[0182] In one modified example, the position of the discharge section in the straight pipe is not particularly limited.

[0183] In one modified example, the discharge section may be provided with multiple openings and multiple guide surfaces.

[0184] In one modified example, the straight pipe section and the discharge section do not have to be formed as a continuous, integrated unit. The straight pipe section and the discharge section may be separate parts. The straight pipe section and the discharge section may be mechanically joined by assembly or the like. The materials of the straight pipe section and the discharge section may be different.

[0185] In one modified example, the material of the piping component does not necessarily have to be rigid polyvinyl chloride. The material of the piping component may be determined according to the requirements of the rain gutter system, and may be, for example, a synthetic resin such as polyethylene.

[0186] In one variation, the rain gutter system 1 does not necessarily have to include a gutter 2. For example, if the building 11 has a structure that includes a drain opening such as a balcony, the downpipe 3 may be connected to the drain opening of the building 11. The same applies to the rain gutter system 10.

[0187] In one modified example, the downpipe 3 may have a different configuration from the example of the above embodiment. The downpipe 3 may have other members in addition to the first vertical pipe 31, the second vertical pipe 32, and the piping member 5. In another example, the downpipe 3 may have the piping member as the upstream end of the downpipe 3. For example, in Figure 1, the piping member 5 may be directly connected to the outlet 2b. For example, in Figure 6, the piping member 5 may be directly connected to the second elbow 7b. The downpipe 3 may consist only of the piping member 5. That is, the piping member 5 may constitute the entire flow path 30 of the downpipe 3.

[0188] [3. Appearance] As is clear from the above embodiments and modifications, this disclosure includes the following aspects. In the following, reference numerals are enclosed in parentheses solely to indicate their correspondence with the embodiments. Note that, for the sake of readability, the notation of reference numerals enclosed in parentheses may be omitted after the first occurrence.

[0189] The first embodiment is a piping member (5;5A;5B;5C;5D;5E;5F;5G;5H;5I;5J;5K) that constitutes part of a downpipe (3) of a rain gutter system (1;1J;10) that utilizes the siphon effect for draining rainwater, comprising a straight pipe section (51;51J) that defines at least part of the flow path (30) of the downpipe (3;3J), and a discharge section (52;52A;52B;52C;52D;52E;52F;52G;52H;52I;52K) that is connected to the straight pipe section (51;51J) and positioned in the flow path (30). The discharge section has an opening (521) with a smaller flow area than the straight pipe section, and a guide surface (522) that guides rainwater passing through the opening (521) toward the central axis (C1) of the straight pipe section (51). This configuration can stably promote the effect of the siphon phenomenon.

[0190] The second embodiment is a piping member (5; 5A; 5B; 5C; 5D; 5E; 5F; 5G; 5H; 5J; 5K) based on the first embodiment. In the second embodiment, the guide surface (522) approaches the central axis (C1) of the straight pipe section (51) as it moves downstream from the opening (521) towards the downpipe (3; 3J). This embodiment makes it easier to guide rainwater passing through the opening (521) toward the central axis (C1) of the straight pipe section (51; 51J), thereby further stably promoting the effect of the siphon phenomenon.

[0191] The third embodiment is a piping member (5; 5A; 5B; 5C; 5D; 5E; 5F; 5G; 5H; 5J; 5K) based on the first or second embodiment. In the third embodiment, the length of the guide surface (522) in the direction of the central axis (C1) of the straight pipe section (51; 51J) is set such that the downstream side of the discharge section (52; 52A; 52B; 52C; 52D; 52E; 52F; 52G; 52H; 52K) in the downpipe (3) becomes full of water before the upstream side of the discharge section (52; 52A; 52B; 52C; 52D; 52E; 52F; 52G; 52H; 52K) in the downpipe (3). This embodiment can stably promote the action due to the siphon phenomenon.

[0192] The fourth embodiment is a piping member (5A; 5F; 5G; 5I) based on any one of the first to third embodiments. In the fourth embodiment, the discharge portion (52A; 52F; 52G; 52I) further has a tapered surface (524) extending from the inner surface (510) of the straight pipe portion (51) toward the opening (521) in a direction that does not perpendicular to the central axis (C1) of the straight pipe portion (51) but intersects it. This embodiment can reduce pressure loss due to the opening (521).

[0193] The fifth embodiment is a piping member (5G) based on the fourth embodiment. In the fifth embodiment, the corner (B1) between the inner surface (510) of the straight pipe section (51) and the tapered surface (524) is rounded in shape. This embodiment can reduce the generation of turbulence at the corner (B1) between the inner surface (510) of the straight pipe section (51) and the tapered surface (524).

[0194] The sixth embodiment is a piping member (5; 5B; 5C; 5D; 5G; 5I; 5K) based on any one of the first to fifth embodiments. In the sixth embodiment, the edge of the opening (521) is rounded. This embodiment can reduce losses at the edge of the opening (521).

[0195] The seventh embodiment is a piping member (5; 5A; 5B; 5C; 5D; 5E; 5F; 5G; 5H; 5I; 5J; 5K) based on any one of the first to sixth embodiments. In the seventh embodiment, the center (O1) of the opening (521) lies on the central axis (C1) of the straight pipe section (51; 51J). This embodiment can stably promote the action due to the siphon phenomenon.

[0196] The eighth embodiment is a piping member (5J) based on any one of the first to seventh embodiments. In the eighth embodiment, the straight pipe section (51J) has a mark (51e) on its outer surface to distinguish it from the vertical pipes (first vertical pipe 31, second vertical pipe 32) used in the downpipe (3J) that have the same dimensions as the straight pipe section (51J). This embodiment can improve the workability of the downpipe (3J).

[0197] The ninth embodiment is a rain gutter system (1;1J;10). The rain gutter system (1;1J;10) has piping members (5;5A;5B;5C;5D;5E;5F;5G;5H;5I;5J;5K) in any one of the first to eighth embodiments, and comprises a downpipe (3;3J) connected to a rainwater outlet (2b) from a building (11;110), and a drain (4) positioned at the outlet (2b). This embodiment can stably promote the action due to the siphon effect.

[0198] The tenth embodiment is a rain gutter system (1;1J) based on the ninth embodiment. In the tenth embodiment, the downpipe (3;3J) is directly connected to the downspout (2b). This embodiment can stably promote the action due to the siphon effect.

[0199] The eleventh embodiment is a rain gutter system (10) based on the ninth embodiment. In the eleventh embodiment, the rain gutter system (10) further comprises a connecting pipe (6) between the downspout (2b) and the downpipe (3), a first elbow (7a) connecting the upstream end (6a) of the connecting pipe (6) to the downspout (2b), and a second elbow (7b) connecting the downstream end (6b) of the connecting pipe (6) to the upstream end (3a) of the downpipe (3). This embodiment can stably promote the action due to the siphon effect.

[0200] The second to eighth aspects described above are optional elements. [Industrial applicability]

[0201] This disclosure is applicable to piping components and rain gutter systems. Specifically, this disclosure is applicable to piping components that constitute part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage, and to rain gutter systems that utilize the siphon effect for rainwater drainage. [Explanation of Symbols]

[0202] 1,1J,10 Rain gutter system 2b Drop-off 3,3J vertical pipe 30 flow channels 4 Drain 5.5A~5K Piping Components 51,51J straight pipe section 51e Mark 52,52A~52I,52L Discharge part 521 Aperture 522 Guide surface 524 Tapered surface 6. Gutter 7a First Elbow 7b Second Elbow B1 Corner (the corner between the inner surface of the straight pipe section and the tapered surface) C1 Center axis C1 O1 center 11,110 buildings

Claims

1. A piping component that constitutes part of the downpipe of a rain gutter system that utilizes the siphon effect for rainwater drainage, A straight pipe section defining at least a portion of the flow path of the downpipe, A discharge section connected to the straight pipe section and positioned in the flow path, Equipped with, The aforementioned discharge section is An opening with a smaller flow area than the aforementioned straight pipe section, A guide surface that directs rainwater passing through the opening toward the central axis of the straight pipe section, It has, The guide surface approaches the central axis of the straight pipe section as it moves downstream from the opening towards the downpipe. The length of the guide surface in the direction of the central axis of the straight pipe section is set such that the downstream side of the downpipe below the discharge section becomes full of water before the upstream side of the downpipe below the discharge section. Piping components.

2. The discharge portion further has a tapered surface extending from the inner surface of the straight pipe portion toward the opening in a direction that does not intersect the central axis of the straight pipe portion but does not perpendicular to it. The piping member according to claim 1.

3. The angle between the inner surface of the straight pipe section and the tapered surface is rounded (R-shaped). The piping member according to claim 2.

4. The edge of the opening is rounded (R-shaped). A piping member according to any one of claims 1 to 3.

5. The center of the opening is on the central axis of the straight pipe section, A piping member according to any one of claims 1 to 4.

6. The straight pipe section has a mark on its outer surface to distinguish it from straight pipes of the same dimensions as the straight pipe section used in the downpipe. A piping member according to any one of claims 1 to 5.

7. A downpipe having a piping member according to any one of claims 1 to 6, and connected to a rainwater outlet from a building, A drain placed at the aforementioned outlet, Equipped with, Rain gutter system.

8. The downpipe is directly connected to the outlet. The rain gutter system according to claim 7.

9. A connecting pipe located between the aforementioned drain outlet and the aforementioned downpipe, A first elbow connects the upstream end of the aforementioned drainpipe to the aforementioned outlet, A second elbow connects the downstream end of the aforementioned downpipe to the upstream end of the aforementioned downpipe, It also has, The rain gutter system according to claim 7.

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