drain

Abstract

This provides a drain that enables a reduction in inlet loss without being constrained by the piping components connected to the eaves gutter. [Solution] The drain comprises a cylindrical portion 21 positioned at the inlet 10b of the bottom wall 10a of the gutter 10, a flange 22 extending outward from the upstream end 21a of the cylindrical portion 21, and a connecting portion 23 located between the upstream end 21a of the cylindrical portion 21 and the flange 22. The connecting portion 23 has a cylindrical reduced-diameter portion 24 whose inner diameter gradually decreases from the flange 22 toward the cylindrical portion 21 until it becomes a value smaller than the inner diameter Du1 of the cylindrical portion 21 (minimum value) Du2, and an enlarged-diameter portion 25 extending outward from the downstream end 24b of the reduced-diameter portion 24 and connected to the upstream end 21a of the cylindrical portion 21. The inner circumferential surface 241 of the reduced-diameter portion 24 is curved in shape, consisting of one or more circular arcs in a cross-section passing through the central axis C21 of the cylindrical portion 21.

Description

Technical Field

[0001] The present disclosure relates to a drain.

Background Art

[0002] Patent Document 1 discloses a drain mounting structure. The drain mounting structure disclosed in Patent Document 1 includes a locking cylinder, a drainage cylinder, and a cover member. The locking cylinder (drain) includes a debris removal portion, an eaves trough locking flange (flange), and a connection cylinder portion (cylinder portion) fitted into a drain opening of an eaves trough. The drainage cylinder is provided with a flange portion at an upper end thereof, is screwed to the connection cylinder portion, and has an engagement ring portion protrudingly provided on an outer peripheral surface thereof. The cover member has an engagement claw portion internally provided to elastically engage with the engagement ring portion, and the cover member is detachably and rotatably attached to the drainage cylinder.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] In the drain disclosed in Patent Document 1, rainwater flows into the cylinder portion through an upper surface of the flange. Here, in a cross-section passing through the central axis of the cylinder portion, when the angle between the upper surface of the flange and the inner peripheral surface of the cylinder portion is 90°, the inlet loss is large, which is one cause of a decrease in flow rate. Accordingly, attempts have been made to reduce inlet loss by connecting the space between the upper surface of the flange and the inner peripheral surface of the cylinder portion with a curved line in the cross-section passing through the central axis of the cylinder portion. However, since the inner diameter of the cylinder portion is restricted by piping members such as a downspout connected to the eaves trough, there have been cases where sufficient reduction of inlet loss cannot be achieved.

[0005] The present disclosure provides a drain that enables reduction of inlet loss without being restricted by a piping member connected to an eaves trough. [Means for solving the problem]

[0006] A drain relating to one aspect of this disclosure is A cylindrical section positioned at the inlet of the bottom wall of the gutter, A flange extending outward from the upstream end of the cylindrical section, The connection between the upstream end of the cylindrical section and the flange, Equipped with, The connection part is, A cylindrical reduced-diameter section in which the inner diameter gradually decreases from the flange toward the cylindrical section until it becomes smaller than the inner diameter of the cylindrical section, An enlarged diameter section extends outward from the downstream end of the reduced diameter section and connects to the upstream end of the cylindrical section, It has, The inner circumferential surface of the reduced-diameter portion is curved, consisting of one or more circular arcs in a cross-section passing through the central axis of the cylindrical portion. [Effects of the Invention]

[0007] Aspects of this disclosure enable the reduction of inlet losses without being constrained by piping components connected to the eaves gutter. [Brief explanation of the drawing]

[0008] [Figure 1] Schematic diagram of a gutter drainage structure including a drain according to an embodiment. [Figure 2] Cross-sectional view of a part of the gutter drainage structure including a drain according to an embodiment. [Figure 3] Perspective view of the drain according to the embodiment [Figure 4] Plan view of the drain according to the embodiment [Figure 5] Bottom view of the drain according to the embodiment [Figure 6] Side view of the drain according to the embodiment [Figure 7] Cross-sectional view of the drain according to the embodiment [Figure 8] Enlarged view of the area indicated by P1 in Figure 7 [Figure 9] Diagram illustrating the installation process of the drain to the gutter according to the embodiment. [Figure 10] Schematic diagram of an example of an existing eaves gutter drainage structure [Figure 11] Explanatory diagram of work for replacing the drain of an existing eaves gutter drainage structure with the drain according to the embodiment [Figure 12] Explanatory diagram of work for replacing the drain of an existing eaves gutter drainage structure with the drain according to the embodiment [Figure 13] Schematic diagram of an eaves gutter drainage structure according to Modification 1 [Figure 14] Schematic diagram of an eaves gutter drainage structure according to Modification 2 [Figure 15] Schematic diagram of an eaves gutter drainage structure according to Modification 3 [Figure 16] Cross-sectional view of a drain according to Modification 4 MODE FOR CARRYING OUT THE INVENTION

[0009] [1. Embodiment] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings as appropriate. However, the following embodiments are examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents (for example, shapes, dimensions, arrangements, etc. of respective components). Unless otherwise specified, positional relationships such as up, down, left and right shall be based on the positional relationships shown in the drawings. Each drawing described in the following embodiments is a schematic diagram, and the ratio of the size and thickness of each component in each drawing does not necessarily reflect the actual dimensional ratio. In addition, the dimensional ratio of each component is not limited to the ratio shown in the drawings.

[0010] In the following description, when it is necessary to distinguish a plurality of components from each other, prefixes such as "first" and "second" are added to the names of the components; however, when the components can be distinguished from each other by the reference numerals assigned thereto, prefixes such as "first" and "second" may be omitted in consideration of readability of the description.

[0011] In the following description, when it is necessary to distinguish between a plurality of constituent elements from each other, suffixes such as "-1" and "-2" are added to the reference numerals of the constituent elements; however, when it is not necessary to distinguish between the plurality of constituent elements, suffixes such as "-1" and "-2" may be omitted in consideration of readability of the description.

[0012] [1.1 Configuration] Fig. 1 is a schematic diagram of an eaves gutter drainage structure 100 including a drain 1 according to an embodiment.

[0013] The eaves gutter drainage structure 100 is a piping system for conveying a fluid having a Reynolds number of 4000 or more. A fluid having a Reynolds number of 4000 or more can be defined as a fluid in which the flow in a cylinder becomes turbulent. Examples of fluids include liquids (drinking water, heat source water, drainage, oil, etc.), gases (air, steam, etc.), and gas-liquid two-phase flows (mixtures of liquid and gas). The eaves gutter drainage structure 100 constitutes a rain gutter system that receives rainwater from a roof 210 of a building 200 and guides the rainwater to a catch basin 310 on the ground 300. The rainwater collected in the catch basin 310 flows out from the catch basin 310 through a buried pipe 320 to a storm sewer. The building 200 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, or a residential facility such as a detached house, an apartment house, or each dwelling unit of a detached house or an apartment house. Non-residential facilities also include theaters, movie theaters, public halls, amusement parks, complex facilities, department stores, hotels, inns, kindergartens, libraries, museums, art museums, underground shopping areas, stations, airports, and the like. The roof 210 may be a flat roof or a folded-plate roof. In Fig. 1, the roof 210 is a folded-plate roof.

[0014] The eaves gutter drainage structure 100 includes a drain 1, an eaves gutter 10, a joint 11, a vertical pipe 12, and a socket 13.

[0015] The gutter 10 receives rainwater from the roof 210 of the building 200. The gutter 10 is installed under the roof 210 of the building 200. For example, the gutter 10 is positioned at the eaves of the roof 210. In particular, the gutter 10 is positioned to extend along the eaves of the roof 210. The gutter 10 is a long, barrel-shaped structure. The gutter 10 has a bottom wall 10a. An inlet 10b is formed in the bottom wall 10a. The inlet 10b is, for example, a circular opening. In a rain gutter system, the inlet 10b is also called a water collection opening, drainage opening, or outlet. For example, the gutter 10 may be formed by extrusion molding of a resin material. The gutter 10 may have a core material to reinforce the overall strength of the gutter 10. The core material may be, for example, metal. Alternatively, the gutter 10 may be formed from a metal sheet, for example, a steel sheet (also called a coil).

[0016] Drain 1 is positioned at the inlet 10b of the gutter 10. Drain 1 is used to reduce the generation of vortices and the entrainment of air at the inlet 10b.

[0017] Figure 2 is a cross-sectional view of a part of the gutter drainage structure 100 including drain 1. The vertical pipe 12 is not shown in Figure 2. Figure 3 is a perspective view of drain 1. Figure 4 is a plan view of drain 1. Figure 5 is a bottom view of drain 1. Figure 6 is a side view of drain 1. Figure 7 is a cross-sectional view of drain 1. Here, Figure 2 is a cross-sectional view along line AA in Figure 4, and Figure 7 is a cross-sectional view along line BB in Figure 4. Figure 8 is an enlarged view of the part indicated by P1 in Figure 7.

[0018] The drain 1 comprises a drain pipe section 2, a funnel section 3, and one or more blades 4. In this embodiment, the drain 1 comprises five blades 4.

[0019] As shown in Figure 2, the drain pipe section 2 has an upstream end 2a and a downstream end 2b. The drain pipe section 2 further has a drain outlet 2c. The drain outlet 2c is the internal space between the upstream end 2a and the downstream end 2b of the drain pipe section 2.

[0020] As shown in Figures 2 and 3, the drain pipe section 2 comprises a cylindrical section 21, a flange 22, and a connecting section 23.

[0021] The cylindrical portion 21 is cylindrical in shape with a central axis C21. The cylindrical portion 21 has an upstream end 21a and a downstream end 21b. The inner diameter and outer diameter of the cylindrical portion 21 do not change. A male threaded portion 21c is formed on the outer circumferential surface of the cylindrical portion 21.

[0022] The inner diameter Du1 of the cylindrical section 21 defines the inner diameter of the drain outlet 2c. The inner diameter Du1 of the drain outlet 2c may be set appropriately according to the dimensions of the piping connected to the drain 1. The dimensions of the piping, 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".

[0023] Table 1 shows an example of nominal diameters for VP rigid polyvinyl chloride pipes in the JIS K 6741 standard for rigid polyvinyl chloride pipes (general). In Table 1, the units for outer diameter (standard dimension), thickness (minimum dimension), and approximate inner diameter are mm.

[0024] [Table 1]

[0025] Table 2 shows an example of nominal diameters for VU rigid polyvinyl chloride pipes in the JIS K 6741 standard for rigid polyvinyl chloride pipes (general). In Table 2, the units for outer diameter (standard dimension), thickness (minimum dimension), and approximate inner diameter are mm.

[0026] [Table 2]

[0027] The inner diameter Du1 of the cylindrical portion 21 may be set based on an approximate inner diameter corresponding to the nominal diameter of the piping. In this embodiment, the inner diameter Du1 of the cylindrical portion 21 may be set to correspond to a nominal diameter of 75 mm, 100 mm, or 125 mm.

[0028] The flange 22 extends outward from the upstream end 21a of the cylindrical portion 21. More specifically, the flange 22 is located at the upstream end 21a of the cylindrical portion 21 and extends radially outward from the cylindrical portion 21. In this embodiment, the flange 22 is annular in shape with a central axis C22. The central axis C22 of the flange 22 and the central axis C21 of the cylindrical portion 21 coincide, and these define the central axis C2 of the drain pipe portion 2.

[0029] The flange 22 has a first surface 22a on the opposite side of the cylindrical portion 21 in the direction of the central axis C21 of the cylindrical portion 21, and a second surface 22b on the side of the cylindrical portion 21. In Figure 2, the first surface 22a is the upper surface of the flange 22, and the second surface 22b is the lower surface of the flange 22. The first surface 22a constitutes part of the surface that guides water into the cylindrical portion 21, so it is preferable that the surface roughness is small. The second surface 22b is the part of the flange 22 that contacts the upper surface of the bottom wall 10a of the gutter 10. In other words, the second surface 22b defines the mounting surface that is placed on the periphery of the inlet 10b of the gutter 10. The width of the second surface 22b is the effective width of the flange 22 that can be used for locking with the bottom wall 10a of the gutter 10. In this embodiment, the second surface 22b is a flat surface, and the normal of the second surface 22b coincides with the central axis C21 of the cylindrical portion 21.

[0030] As can be seen from Figures 4 and 5, the central axis C2 of the drain pipe section 2 coincides with the central axis C21 of the pipe section 21 and the central axis C22 of the flange 22.

[0031] In the drain pipe section 2, the flange 22 defines the upstream end 2a, and the downstream end 21b of the pipe section 21 defines the downstream end 2b.

[0032] The connecting portion 23 is located between the upstream end 21a of the cylindrical portion 21 and the flange 22. The connecting portion 23 has a reduced diameter portion 24 and an enlarged diameter portion 25.

[0033] The reduced diameter portion 24 is cylindrical with an inner diameter that gradually decreases from the flange 22 toward the cylindrical portion 21. The reduced diameter portion 24 has an upstream end 24a and a downstream end 24b. In the present embodiment, the flange 22 extends outward from the upstream end 24a of the reduced diameter portion 24. The reduced diameter portion 24 enables a reduction in inlet loss compared to the case where the angle between the first surface 22a of the flange 22 and the inner peripheral surface of the cylindrical portion 21 is 90°. In particular, in the present embodiment, the inner diameter of the reduced diameter portion 24 gradually decreases from the value equal to the inner diameter of the flange 22 toward the cylindrical portion 21 from the flange 22, until it becomes a value smaller than the inner diameter Du1 of the cylindrical portion 21. That is, the inner diameter of the reduced diameter portion 24 is minimized at the downstream end of the reduced diameter portion 24. When the minimum value of the inner diameter of the reduced diameter portion 24 is defined as Du2, Du2 < Du1 holds. Therefore, in a cross section passing through the central axis C21 of the cylindrical portion 21, the reduced diameter portion 24 enables a reduction in inlet loss compared to the case where the first surface 22a of the flange 22 and the inner peripheral surface of the cylindrical portion 21 are connected by a curved line. In the present embodiment, the outer diameter of the reduced diameter portion 24 gradually decreases from the value equal to the inner diameter of the flange 22 toward the cylindrical portion 21 from the flange 22, until it becomes a value smaller than the outer diameter of the cylindrical portion 21. That is, the outer diameter of the reduced diameter portion 24 is minimized at the downstream end 24b of the reduced diameter portion 24. The minimum value of the outer diameter of the reduced diameter portion 24 is smaller than the outer diameter of the cylindrical portion 21.

[0034] The reduced diameter portion 24 has an inner peripheral surface 241 and an outer peripheral surface 242.

[0035] As shown in FIG. 3, the inner peripheral surface 241 of the reduced diameter portion 24 has a curved shape formed of one or more circular arcs in a cross section passing through the central axis C21 of the cylindrical portion 21. When the representative value of the radius of curvature defining the inner peripheral surface 241 in a cross section passing through the central axis C21 of the cylindrical portion 21 is defined as Ri [mm], Ri > 10 mm is satisfied. This enables a further reduction in the inlet loss of the drain 1. The above "representative value" may be the radius of curvature of the longest circular arc among one or more circular arcs defining the inner peripheral surface 241 in a cross section passing through the central axis C21 of the cylindrical portion 21. Furthermore, the "representative value" may be the average value of radii of curvature defining the inner peripheral surface 241 in a cross section passing through the central axis C21 of the cylindrical portion 21, or the radius of curvature of the circular arc closest to the inner peripheral surface 241 in a cross section passing through the central axis C21 of the cylindrical portion 21.

[0036] Here, it is preferable that Ri / 3 ≤ Du1 ≤ Du1 - Du2 ≤ Ri / 2 for the inner diameter Du1 of the cylindrical portion 21, the minimum value Du2 of the inner diameter of the reduced diameter portion 24, and the representative value Ri of the radius of curvature defining the inner circumferential surface 241 in the cross-section passing through the central axis C21 of the cylindrical portion 21.

[0037] Let D [mm] be the maximum inner diameter of the piping member (in this embodiment, the socket 13) that can be connected to the inlet 10b. It is preferable that 0.05D ≤ Ri ≤ 0.20D be satisfied. Furthermore, it is preferable that 40 ≤ D ≤ 150 be satisfied. The maximum inner diameter of the piping member that can be connected to the inlet 10b is the inner diameter of the piping member with the largest inner diameter among the piping members that can be connected to the inlet 10b via the drain 1. For example, if two types of piping members are available, one with a nominal diameter of 100 and the other with a nominal diameter of 75, the inner diameter of the piping member with a nominal diameter of 100 will be the maximum inner diameter of the piping member that can be connected to the inlet 10b. For example, the piping member with a nominal diameter of 100 may be the socket 13. In Figure 2, the socket 13a is shown as the piping member with a nominal diameter of 75 by a dashed line.

[0038] The outer circumferential surface 242 of the reduced diameter portion 24 is curved, consisting of one or more circular arcs, in a cross-section passing through the central axis C21 of the cylindrical portion 21. For example, the representative value of the radius of curvature defining the outer circumferential surface 242 in a cross-section passing through the central axis C21 of the cylindrical portion 21 can be set based on the representative value of the radius of curvature defining the inner circumferential surface 241 in a cross-section passing through the central axis C21 of the cylindrical portion 21, so that the thickness of the reduced diameter portion 24 becomes as uniform as possible. This can reduce the possibility of sink marks occurring on the outer circumferential surface 242 of the reduced diameter portion 24. Note that the "representative value" of the radius of curvature for the outer circumferential surface 242 may be the radius of curvature of the longest of the one or more circular arcs defining the outer circumferential surface 242, or the average value of the radii of curvature defining the outer circumferential surface 242 in a cross-section passing through the central axis C21 of the cylindrical portion 21, or the radius of curvature of the circular arc closest to the outer circumferential surface 242 in a cross-section passing through the central axis C21 of the cylindrical portion 21.

[0039] The enlarged diameter portion 25 extends outward from the downstream end 24b of the reduced diameter portion 24 and connects to the upstream end 21a of the cylindrical portion 21. The enlarged diameter portion 25 is the part that absorbs the difference between the inner diameter Du1 of the cylindrical portion 21 and the minimum value Du2 of the inner diameter of the reduced diameter portion 24. In this embodiment, the enlarged diameter portion 25 extends from the downstream end 24b of the reduced diameter portion 24 along the radial direction of the central axis C21 of the cylindrical portion 21. The enlarged diameter portion 25 is an annular shape centered on the central axis C21 of the cylindrical portion 21. The outer diameter of the enlarged diameter portion 25 is equal to the outer diameter of the cylindrical portion 21.

[0040] The funnel section 3 is a connecting section that links the five blades 4 together. As shown in Figures 2 and 3, the funnel section 3 is located at the upstream end 2a of the drain pipe section 2. More specifically, the funnel section 3 is positioned opposite the upstream end 2a of the drain pipe section 2, such that the central axis C3 of the funnel section 3 coincides with the central axis C2 of the drain pipe section 2.

[0041] As shown in Figures 2 and 7, the funnel section 3 has a first opening 3a and a second opening 3b. The funnel section 3 directs the fluid flowing in through the first opening 3a to the outlet 2c of the drain pipe section 2 through the second opening 3b.

[0042] The funnel portion 3 has a reduced diameter portion 31, a small diameter cylindrical portion 32, and a flange 33.

[0043] As shown in Figure 7, the reduced diameter portion 31 is cylindrical in shape, with its outer and inner diameters decreasing as it approaches the drain pipe portion 2. The reduced diameter portion 31 can also be described as a hollow frustoconical shape with open ends. The reduced diameter portion 31 has a first surface 311 and a second surface 312. The first surface 311 is the inner circumferential surface of the reduced diameter portion 31. The first surface 311 defines the surface of the reduced diameter portion 31 opposite to the drain pipe portion 2. The second surface 312 is the outer circumferential surface of the reduced diameter portion 31. The second surface 312 defines the surface of the reduced diameter portion 31 facing the drain pipe portion 2. In this embodiment, the maximum outer diameter of the reduced diameter portion 31 is smaller than the inner diameter of the drain pipe portion 2 (the inner diameter of the cylindrical portion 21). In this embodiment, the inclination angle of the first surface 311 of the reduced diameter portion 31 in a cross-section passing through the central axis of the reduced diameter portion 31 is 40 degrees or more and 60 degrees or less.

[0044] The small-diameter cylindrical portion 32 extends from the end of the reduced-diameter portion 31 on the drain pipe portion 2 side (the lower end in Figure 2) towards the drain pipe portion 2. The small-diameter cylindrical portion 32 is cylindrical with less change in inner and outer diameter than the reduced-diameter portion 31. The interior of the small-diameter cylindrical portion 32 is connected to the interior of the reduced-diameter portion 31. The outer and inner circumferential surfaces of the small-diameter cylindrical portion 32 are substantially perpendicular to the central axis of the drain pipe portion 2, and are neither the surface on the drain pipe portion 2 side nor the surface on the opposite side of the drain pipe portion 2.

[0045] The flange 33 extends radially outward from the end of the reduced-diameter portion 31 opposite to the drain pipe portion 2 (the upper end in Figure 7). The flange 33 is plate-shaped and has a first surface 331 and a second surface 332. The first surface 331 is the upper surface of the flange 33. The first surface 331 defines the surface of the flange 33 opposite to the drain pipe portion 2. The second surface 332 is the lower surface of the flange 33. The second surface 332 defines the surface of the flange 33 facing the drain pipe portion 2. The flange 33 is annular. In this embodiment, the outer diameter of the flange 33 is smaller than the inner diameter of the drain pipe portion 2 (the inner diameter of the pipe portion 21).

[0046] As can be seen from Figures 4 and 5, in the funnel portion 3, the opening at the end of the reduced diameter portion 31 opposite to the drain pipe portion 2 is the first opening 3a, and the opening at the end of the small diameter portion 32 on the drain pipe portion 2 side is the second opening 3b.

[0047] As can be seen from Figures 2 and 7, in this embodiment, the funnel portion 3 is not located inside the drain pipe portion 2. Here, in the direction of the central axis C2 of the drain pipe portion 2, the distance between the second opening 3b and the drain pipe portion 2 is preferably less than half the distance between the first opening 3a and the drain pipe portion 2. In this embodiment, the end of the small-diameter cylindrical portion 32 of the funnel portion 3 on the drain pipe portion 2 side (second opening 3b) and the upstream end 2a of the drain pipe portion 2 are on the same plane. In other words, the minimum distance between the funnel portion 3 and the drain pipe portion 2, i.e., the distance between the second opening 3b and the drain pipe portion 2, is 0.

[0048] As can be seen from Figures 4 and 5, the central axis C3 of the funnel portion 3 coincides with the central axis of the reduced diameter portion 31, the central axis of the small diameter cylindrical portion 32, and the central axis of the flange 33.

[0049] In the funnel portion 3, the first surface 311 of the reduced diameter portion 31 and the first surface 331 of the flange 33 constitute the surface of the funnel portion 3 opposite to the drain pipe portion 2. In the funnel portion 3, the second surface 312 of the reduced diameter portion 31 and the second surface 332 of the flange 33 constitute the surface of the funnel portion 3 facing the drain pipe portion 2. Furthermore, the outer circumference 33a of the flange 33 constitutes the outer circumference of the funnel portion 3 when viewed from the direction of the central axis C2 of the drain pipe portion 2.

[0050] Let d be the diameter representing the outer shape of the funnel portion 3 as viewed from the direction of the central axis C2 of the drain pipe portion 2. Preferably, d is set to satisfy 0.6D ≤ d ≤ 1.5D. In this embodiment, d ≤ 1.0D. Here, the diameter d may be the diameter of the largest circle that tangent to any two points of the funnel portion 3 as viewed from the direction of the central axis C2 of the drain pipe portion 2. In this embodiment, since the funnel portion 3 is circular as viewed from the direction of the central axis C2 of the drain pipe portion 2, the diameter d is equal to the diameter of the funnel portion 3 (especially the diameter of the flange 33) as viewed from the direction of the central axis C2 of the drain pipe portion 2.

[0051] As shown in Figures 3 to 5, in this embodiment, there are 5 blades 4. The 5 blades 4 are all the same shape. As shown in Figure 4, when viewed from the direction of the central axis C2 of the drain pipe 2, the 5 blades 4 are arranged at equal intervals around the central axis C2 of the drain pipe 2.

[0052] Each blade 4 protrudes from the upstream end 2a of the drain pipe section 2 in the direction of the central axis C2 of the drain pipe section 2. The blades 4 are connected to each other by the funnel section 3. In this embodiment, five blades 4 are connected to the funnel section 3. More specifically, the blades 4 connect the upstream end 2a of the drain pipe section 2 to the side of the funnel section 3 opposite to the drain pipe section 2. In other words, the funnel section 3 is positioned at the upstream end 2a of the drain pipe section 2 so as to be suspended from the blades 4.

[0053] The wing 4 comprises a main body 41, an arm 42, and a reinforcing part 43.

[0054] The main body portion 41 is plate-shaped. In particular, the main body portion 41 is rectangular plate-shaped. The main body portion 41 protrudes from the upstream end 2a of the drain pipe portion 2. In particular, the main body portion 41 protrudes from the upstream end 2a of the drain pipe portion 2 along the central axis C2 of the drain pipe portion 2. The direction of the central axis C2 of the drain pipe portion 2 corresponds to the height direction of the main body portion 41. The main body portion 41 extends in the radial direction of the drain pipe portion 2 when viewed from the direction of the central axis C2 of the drain pipe portion 2. The radial direction of the drain pipe portion 2 corresponds to the length direction of the main body portion 41. The width direction (thickness direction) of the main body portion 41 is perpendicular to the radial direction of the drain pipe portion 2 when viewed from the direction of the central axis C2 of the drain pipe portion 2. The width of the main body portion 41 defines the width of the blade 4. If the width of the blade 4 is t, it is preferable that the drain 1 satisfies 2 mm ≤ t ≤ 6 mm.

[0055] The main body portion 41 has a first end portion 41a, a second end portion 41b, a third end portion 41c, and a fourth end portion 41d.

[0056] The first end 41a and the second end 41b are the ends of the main body 41 in the longitudinal direction. In particular, the first end 41a is the end of the drain pipe 2 on the side of the central axis C2 when viewed from the direction of the central axis C2 of the drain pipe 2. The second end 41b is the end of the drain pipe 2 on the opposite side of the central axis C2 when viewed from the direction of the central axis C2 of the drain pipe 2.

[0057] As can be seen from Figures 2 and 5, the corner of the first end 41a of the main body 41 is fillet-shaped when viewed from the direction of the central axis C2 of the drain pipe 2. In particular, the corner of the first end 41a of the main body 41 is a convex fillet shape. This makes it less likely for the worker's hand to hurt when touching the corner of the first end 41a when holding the blade 4 during the installation of the drain 1. Therefore, it becomes easier for the worker to hold the blade 4 during the installation of the drain 1. Note that the corner of the first end 41a of the main body 41 may be tapered when viewed from the direction of the central axis C2 of the drain pipe 2.

[0058] In the blade 4, as shown in Figures 2 and 5, the distance between the first end 41a of the main body 41 and the central axis C2 of the drain pipe 2, as viewed from the direction of the central axis C2 of the drain pipe 2, is denoted as b. It is preferable that b is set to satisfy 0.40d ≤ b ≤ 0.75d. When b is 0.40d or greater, the space between the drain pipe 2, the funnel 3, and the blade 4 can be widened while obtaining the flow straightening effect of the blade 4, thereby further suppressing the deterioration of drainage function caused by foreign matter. On the other hand, if b becomes too large, the entire drain 1 will become larger, so it is preferable that b be 0.75d or less.

[0059] In particular, in this embodiment, when viewed from the direction of the central axis C2 of the drain pipe section 2, the first end portion 41a of the main body section 41 is located outside the reduced diameter section 31. This allows for a further widening of the space between the drain pipe section 2, the funnel section 3, and the blades 4. Therefore, it is possible to further suppress the deterioration of drainage function caused by foreign matter. In addition, a swirling flow is more likely to occur between the reduced diameter section 31 and the blades 4, and an improvement in drainage function can be expected.

[0060] In particular, in this embodiment, when viewed from the direction of the central axis C2 of the drain pipe section 2, the first end portion 41a of the main body section 41 is located outside the flange 33. This configuration allows for a further widening of the space between the drain pipe section 2, the funnel section 3, and the vane 4. Therefore, it is possible to further suppress the deterioration of drainage function caused by foreign matter.

[0061] On the other hand, when viewed from the direction of the central axis C2 of the drain pipe section 2, the first end portion 41a of the main body section 41 is located inside the outlet 2c of the drain pipe section 2. This allows for an improvement in the flow straightening effect of the blades 4.

[0062] As shown in Figures 2 and 7, the first end portion 41a of the main body portion 41 is inclined to move away from the central axis C2 of the drain pipe portion 2 as it approaches the drain pipe portion 2. This allows for a wider space between the drain pipe portion 2, the funnel portion 3, and the blades 4. This further suppresses the deterioration of drainage function caused by foreign matter.

[0063] As can be seen from Figures 3 and 4, when viewed from the direction of the central axis C2 of the drain pipe section 2, the corners (both corners in this embodiment) of the second end 41b of the main body section 41 are fillet-shaped. In particular, the corners of the second end 41b of the main body section 41 are convex fillet-shaped. This makes it less likely for a worker's hand to hurt when touching the corners of the second end 41b when holding the blades 4 during the installation of the drain 1. Therefore, it becomes easier for a worker to hold the blades 4 during the installation of the drain 1. Note that when viewed from the direction of the central axis C2 of the drain pipe section 2, the corners of the second end 41b of the main body section 41 may be tapered.

[0064] The third end 41c and the fourth end 41d are the ends of the main body 41 in the height direction. In particular, the third end 41c is the end opposite to the drain pipe 2 in the direction of the central axis C2 of the drain pipe 2. The fourth end 41d is the end on the drain pipe 2 side in the direction of the central axis C2 of the drain pipe 2.

[0065] The third end portion 41c is further from the drain pipe portion 2 than the first surface 331 of the flange 33 of the funnel portion 3, in the direction of the central axis C2 of the drain pipe portion 2. In the direction of the central axis C2 of the drain pipe portion 2, the distance between the end portion (third end portion 41c) of one or more blades 4 opposite to the drain pipe portion 2 and the surface of the funnel portion 3 opposite to the drain pipe portion 2 (first surface 331 of the flange 33) is 5 mm or more and 15 mm or less. That is, as shown in Figure 6, if a1 is the distance between the end portion (third end portion 41c) of one or more blades 4 opposite to the drain pipe portion 2 in the direction of the central axis C2 of the drain pipe portion 2 and the drain pipe portion 2, and a2 is the distance between the surface of the funnel portion 3 opposite to the drain pipe portion 2 (first surface 331) and the drain pipe portion 2 in the direction of the central axis C2 of the drain pipe portion 2, then the condition 5 mm ≤ a1 - a2 ≤ 15 mm is satisfied. Here, if we let a1-a2=a, then a represents the distance between the end of the blade 4 opposite to the drain pipe section 2 (third end 41c) and the surface of the funnel section 3 opposite to the drain pipe section 2 (first surface 331) in the direction of the central axis C2 of the drain pipe section 2. This makes it possible to improve the strength of the connection between the funnel section 3 and the blade 4. Here, it is more preferable that a(=a1-a2)=9mm.

[0066] The fourth end portion 41d is also the portion of the main body 41 that is connected to the drain pipe portion 2.

[0067] In the direction of the central axis C2 of the drain pipe section 2, the main body section 41 is connected to the flange 22 and the connecting section 23 of the drain pipe section 2. Since the main body section 41 extends not only to the flange 22 of the drain pipe section 2 but also to the connecting section 23, the strength of the blade 4 can be maintained.

[0068] In this embodiment, as shown in Figures 4 and 6, the main body portion 41 has fillets 41e, 41e at the end (fourth end portion 41d) on the drain pipe portion 2 side, which increase the width of the main body portion 41 as it approaches the drain pipe portion 2 in the direction of the central axis C2 of the drain pipe portion 2. In this embodiment, the fillets 41e, 41e are located on both sides in the width direction of the main body portion 41. The surface of the fillets 41e is concave. The fillets 41e enable improved strength of the vanes 4 against the drain pipe portion 2. In this embodiment, as shown in Figures 4 and 7, the fillets 41e extend along the main body portion 41 and, like the main body portion 41, extend not only to the flange 22 of the drain pipe portion 2 but also to the connecting portion 23. The fillets 41e include a first portion 41e1 on the flange 22 and a second portion 41e2 on the connecting portion 23. In particular, in the second portion 41e2, at least one of the radius of curvature or width of the fillet 41e decreases from the second end 41b to the first end 41a of the main body 41. This allows for improved drainage function by the fillet 41e. In the second portion 41e2, the radius of curvature or width of the fillet 41e may be reduced to 0.

[0069] The arm portion 42 connects the funnel portion 3 to the main body portion 41 on the side opposite to the drain pipe portion 2 (first surface 311, 331). The arm portion 42 protrudes toward the funnel portion 3 from the end of the main body portion 41 opposite to the drain pipe portion 2 (third end portion 41c). When viewed from the direction of the central axis C2 of the drain pipe portion 2, the arm portion 42 extends in the radial direction of the drain pipe portion 2. The width direction of the arm portion 42 is perpendicular to the radial direction of the drain pipe portion 2 when viewed from the direction of the central axis C2 of the drain pipe portion 2. As an example, the width of the arm portion 42 is preferably 2 mm or more and 6 mm or less.

[0070] As shown in Figures 2 to 4, the arm portion 42 extends from the main body portion 41 to the first surface 331 of the flange 33 and the first surface 311 of the reduced diameter portion 31 of the funnel portion 3. The arm portion 42 connects the flange 33 and the reduced diameter portion 31 to the main body portion 41. In other words, the arm portion 42 has a first portion 42a and a second portion 42b. The first portion 42a is the part of the arm portion 42 that is connected to the flange 33. The second portion 42b is the part of the arm portion 42 that is connected to the reduced diameter portion 31. The height of the first portion 42a relative to the drain pipe portion 2 does not change as it approaches the center of the reduced diameter portion 31. The height of the second portion 42b relative to the drain pipe portion 2 decreases as it approaches the center of the reduced diameter portion 31. The height of the first part 42a or the second part 42b relative to the drain pipe section 2 is the distance between the end of the first part 42a or the second part 42b opposite to the drain pipe section 2 in the direction of the central axis C2 of the drain pipe section 2 and the drain pipe section 2. This makes it possible to increase the inflow of rainwater into the funnel section 3. Furthermore, even when rainwater flows into the funnel section 3, the possibility of vortex formation in the drain pipe section 2 can be reduced.

[0071] As shown in Figures 2 and 4, let c be the length of the connection between the arm portion 42 and the funnel portion 3 as viewed from the direction of the central axis C2 of the drain pipe portion 2. In this embodiment, c is equal to the distance between the tip of the arm portion 42 and the outer circumference of the funnel portion 3 (outer circumference 33a of the flange 33) as viewed from the direction of the central axis C2 of the drain pipe portion 2. It is preferable that c be set to satisfy 0.1d ≤ c ≤ 0.5D. When c is 0.1d or greater, it is possible to improve the strength of the connection between the funnel portion 3 and the blade 4. When c is 0.5D or less, it is possible to form a first opening 3a and a second opening 3b of sufficient size in the funnel portion 3. As shown in Figures 2 and 4, let e be the distance between the tip of the arm portion 42 and the central axis C2 of the drain pipe portion 2 as viewed from the direction of the central axis C2 of the drain pipe portion 2. It is preferable that e ≤ 0.25d. This is possible to improve the strength of the connection between the funnel portion 3 and the blade 4.

[0072] In this embodiment, as shown in Figures 4 and 7, the width of the arm portion 42 increases as it approaches the central axis C2 of the drain pipe portion 2 when viewed from the direction of the central axis C2 of the drain pipe portion 2. In particular, at the tip portion of the second portion 42b of the arm portion 42, the width of the arm portion 42 increases as it approaches the central axis C2 of the drain pipe portion 2 when viewed from the direction of the central axis C2 of the drain pipe portion 2. This makes it possible to improve the strength of the connection between the funnel portion 3 and the blades 4. The minimum width of the arm portion 42 is equal to the width of the main body portion 41.

[0073] In this embodiment, as shown in Figures 4, 7, and 8, the arm portion 42 has fillets 42c, 42c at the end (lower end) on the drain pipe portion 2 side, such that the width of the arm portion 42 increases as it approaches the drain pipe portion 2 in the direction of the central axis C2 of the drain pipe portion 2. In this embodiment, the fillets 42c, 42c are located on both sides of the arm portion 42 in the width direction. The surface of the fillets 42c is concave. The fillets 42c enable improved strength of the connection between the funnel portion 3 and the blades 4. In this embodiment, as shown in Figures 4 and 7, the fillets 42c extend along the arm portion 42 and, like the arm portion 42, extend not only to the flange 33 of the funnel portion 3 but also to the reduced diameter portion 31. In particular, at the tip of the fillets 42c, at least one of the radius of curvature or width of the fillets 42c decreases as it approaches the central axis C2 of the funnel portion 3. This enables improved drainage function by the fillets 42c. At the tip of the fillet 42c, the radius of curvature or width of the fillet 42c may be reduced to 0.

[0074] The reinforcing portion 43 is provided to improve the strength of the blade 4. As shown in FIG. 4, when viewed from the direction of the central axis C2 of the drain cylinder portion 2, the reinforcing portion 43 is located at a position overlapping the outer peripheral portion of the funnel portion 3 (the outer peripheral portion 33a of the flange 33). The width direction of the reinforcing portion 43 is orthogonal to the radial direction of the drain cylinder portion 2 when viewed from the direction of the central axis C2 of the drain cylinder portion 2. As can be particularly understood from FIG. 8, the width of the reinforcing portion 43 increases as it approaches the funnel portion 3 (the flange 33) in the direction of the central axis C2 of the drain cylinder portion 2. When a force is applied to the funnel portion 3 or the blade 4, stress tends to concentrate on a portion of the blade 4 corresponding to the outer peripheral portion of the funnel portion 3. Therefore, the provision of the reinforcing portion 43 can reduce the possibility of damage to the blade 4 caused by such stress. Let the maximum value of the width of the reinforcing portion 43 be t1. It is preferable that t1 is set to satisfy 1.1t < t1 < 1.4t.

[0075] In the present embodiment, referring to FIG. 2 and FIG. 3, in the direction of the central axis C2 of the drain cylinder portion 2, the surface 43a of the reinforcing portion 43 on the drain cylinder portion 2 side is farther from the drain cylinder portion 2 than the surface of the outer peripheral portion of the funnel portion 3 on the drain cylinder portion 2 side (the second surface 332 of the flange 33). In FIG. 2, the position of the surface 43a of the reinforcing portion 43 on the drain cylinder portion 2 side is indicated by h1, and the position of the surface of the outer peripheral portion of the funnel portion 3 on the drain cylinder portion 2 side (the second surface 332 of the flange 33) is indicated by h2. Accordingly, when a force is applied to the funnel portion 3 or the blade 4, the reinforcing portion 43 easily absorbs stress, thereby reducing the possibility of damage to the blade 4.

[0076] In the present embodiment, the reinforcing portion 43 is located between the main body portion 41 and the arm portion 42 when viewed from the direction of the central axis C2 of the drain cylinder portion 2. When a force is applied to the funnel portion 3 or the blade 4, stress tends to concentrate on the connecting portion between the main body portion 41 and the arm portion 42 in the blade 4. Therefore, the provision of the reinforcing portion 43 can reduce the possibility of damage to the blade 4 caused by such stress.

[0077] In this embodiment, the reinforcing portion 43 is positioned to overlap with the outer circumference of the funnel portion 3 (the outer circumference 33a of the flange 33) when viewed from the direction of the central axis C2 of the drain pipe portion 2. Furthermore, in the direction of the central axis C2 of the drain pipe portion 2, the surface 43a of the reinforcing portion 43 on the drain pipe portion 2 side is further away from the drain pipe portion 2 than the surface on the outer circumference of the funnel portion 3 on the drain pipe portion 2 side (the second surface 332 of the flange 33). As a result, as shown in Figure 2, there is a gap G between the main body portion 41 and the end of the outer circumference of the funnel portion 3 on the drain pipe portion 2 side. Due to this gap G, the blades 4 do not come into contact with the radially outer end of the drain pipe portion 2 on the second surface 332 of the flange 33. Due to this gap G, the main body portion 41 of the blades 4 and the flange 33 of the funnel portion 3 are spaced apart from each other in the radial direction of the drain pipe portion 2. Therefore, the space between the drain pipe section 2, the funnel section 3, and the blades 4 can be widened, making it possible to further suppress the deterioration of drainage function caused by foreign matter. In particular, the presence of the gap G makes it easier for swirling flow to occur between the reduced diameter section 31 and the blades 4, and an improvement in drainage function can be expected.

[0078] In this embodiment, as shown in Figure 2, the blades 4 do not come into contact with the surface of the funnel portion 3 on the drain pipe portion 2 side (second surfaces 312, 332). Therefore, the space between the funnel portion 3 and the drain pipe portion 2 can be widened, reducing the possibility of foreign objects getting stuck. Thus, the drain 1 enables improved flow straightening and suppression of the deterioration of drainage function caused by foreign objects. In particular, in this embodiment, the blades 4 are not located between the funnel portion 3 and the drain pipe portion 2. Therefore, the space between the funnel portion 3 and the drain pipe portion 2 can be widened even further, further reducing the possibility of foreign objects getting stuck. Thus, the drain 1 enables further suppression of the deterioration of drainage function caused by foreign objects.

[0079] Refer to Figure 2 again. The fitting 11 is used to connect the drain 1 to a piping member. The piping member may be, for example, a straight pipe, an elbow, or a socket. In this embodiment, the fitting 11 is connected to the vertical pipe 12 via a socket 13.

[0080] The joint 11 has a first cylindrical portion 111, a first flange 112, a connecting portion 113, a second flange 114, and a second cylindrical portion 115.

[0081] The first cylindrical portion 111 is cylindrical in shape. The first cylindrical portion 111 has an upstream end 111a and a downstream end 111b. A female threaded portion 111c is formed on the inner circumferential surface of the first cylindrical portion 111. The inner diameter of the first cylindrical portion 111 is larger than the outer diameter of the cylindrical portion 21 of the drain pipe portion 2 of the drain 1. The female threaded portion 111c of the first cylindrical portion 111 corresponds to the male threaded portion 21c of the drain pipe portion 2 of the drain 1.

[0082] The first flange 112 is located at the upstream end 111a of the first cylindrical portion 111 and extends radially outward from the first cylindrical portion 111.

[0083] The connecting portion 113 is located between the upstream end 111a of the first cylindrical portion 111 and the first flange 112. The connecting portion 113 is cylindrical in shape, with its inner diameter gradually increasing from the first cylindrical portion 111 toward the first flange 112. The inner circumferential surface of the connecting portion 113 may be an R-shape with a radius of curvature of 10 mm or less in a cross-section passing through the central axis of the first cylindrical portion 111, or a tapered shape (C-shape) with sides of 10 mm or less. There is no step of 3 mm or more on the inner circumferential surface of the connecting portion 113.

[0084] The second flange 114 is located at the downstream end 111b of the first cylindrical portion 111 and extends radially inward of the first cylindrical portion 111.

[0085] The second cylindrical portion 115 is cylindrical in shape, with smaller outer and inner diameters than the first cylindrical portion 111. The second cylindrical portion 115 protrudes from the inner circumference of the second flange 114 along the central axis of the first cylindrical portion 111.

[0086] The fitting 11 has first and second cylindrical sections 111 and 115 with different outer diameters, which allows it to be connected to piping members of different sizes. For example, the first cylindrical section 111 may correspond to a piping member (socket 13) with a nominal diameter of 100, and the second cylindrical section 115 may correspond to a piping member (socket 13a) with a nominal diameter of 75.

[0087] In the eaves gutter drainage structure 100, the drain 1 is attached to the eaves gutter 10 using a joint 11.

[0088] The installation of a new gutter drainage structure 100 will be explained with reference to Figure 9. Figure 9 is an explanatory diagram of the installation of the drain 1 to the gutter 10. As shown in Figure 9, the drain 1 is positioned at the inlet 10b of the gutter 10 from the upper side of the gutter 10 (S11). As a result, as shown in Figure 2, the cylindrical portion 21 of the drain pipe 2 is located below the inlet 10b of the bottom wall 10a of the gutter 10, and the flange 22 of the drain pipe 2, at its second surface 22b, touches the upper surface of the peripheral edge of the inlet 10b of the bottom wall 10a of the gutter 10. After this, the joint 11 is attached to the drain 1 from the lower side of the gutter 10 (S12). The joint 11 is attached to the cylindrical portion 21 of the drain pipe 2 below the inlet 10b. More specifically, the downstream end 21b of the cylindrical portion 21 of the drain pipe 2 of the drain 1 is inserted into the first cylindrical portion 111 of the joint 11. As a result, the male threaded portion 21c of the cylindrical portion 21 engages with the female threaded portion 111c of the first cylindrical portion 111. From this point, as the joint 11 is rotated relative to the drain 1, the first flange 112 of the joint 11 eventually comes into contact with the lower surface of the peripheral edge of the inlet 10b of the bottom wall 10a of the gutter 10. In this way, the drain 1 and the joint 11 are attached to the gutter 10 by sandwiching the peripheral edge of the inlet 10b of the gutter 10 from both above and below.

[0089] Drain 1 can be used not only when installing a new gutter drainage structure 100, but also with existing gutter drainage structures.

[0090] Figure 10 is a schematic diagram of an example of an existing gutter drainage structure 100P. The gutter drainage structure 100P includes a drain 5 and a joint 11. The gutter drainage structure 100P includes a vertical pipe 12 and a socket 13, similar to the gutter drainage structure 100.

[0091] The drain 5 comprises a drain pipe section 6, a funnel section 7, and four support sections 8.

[0092] The drain pipe section 6 has an upstream end 6a and a downstream end 6b. The drain pipe section 6 further has a drain outlet 6c. The drain outlet 6c is the internal space between the upstream end 6a and the downstream end 6b of the drain pipe section 6.

[0093] The drain pipe section 6 comprises a cylindrical section 61 and a flange 62. The cylindrical section 61 is cylindrical in shape. The cylindrical section 61 has an upstream end 61a and a downstream end 61b. Male threads 61c are formed on the outer circumferential surface of the cylindrical section 61. The inner diameter Du3 of the cylindrical section 61 is equal to the inner diameter Du1 of the cylindrical section 21 of the drain 1. The flange 62 is annular in shape. The flange 62 extends outward from the upstream end 61a of the cylindrical section 61. The flange 62 has a first surface 62a opposite to the cylindrical section 61 in the direction of the central axis of the cylindrical section 61 and a second surface 62b on the cylindrical section 61 side. The inner diameter of the flange 62 is equal to the inner diameter of the flange 22 of the drain 1.

[0094] In the drain pipe section 6, the first surface 62a of the flange 62 and the inner circumferential surface of the pipe section 61 are connected by a curve in a cross-section passing through the central axis of the pipe section 61. The inner diameter Du3 of the pipe section 61 is equal to the inner diameter Du1 of the pipe section 21 of the drain 1, and the inner diameter of the flange 62 is equal to the inner diameter of the flange 22 of the drain 1. In the drain 1, the inner diameter of the reduced diameter section 24 gradually decreases from the flange 22 toward the pipe section 21, from a value equal to the inner diameter of the flange 22 to a value smaller than the inner diameter Du1 of the pipe section 21. Therefore, the drain 1 has a smaller inlet loss than the drain 5, which allows for improved flow rate and thus improved drainage capacity.

[0095] The funnel portion 7 is positioned opposite the upstream end 61a of the cylindrical portion 61. The funnel portion 7 is cylindrical in shape, with its outer and inner diameters decreasing as it approaches the cylindrical portion 61.

[0096] The support parts 8 support the funnel section 7 relative to the drain pipe section 6. Viewed from the direction of the central axis of the drain pipe section 6, the four support parts 8 are arranged at equal intervals around the central axis of the drain pipe section 6.

[0097] The case of applying Drain 1 to an existing gutter drainage structure 100P will be explained with reference to Figures 11 and 12. Figures 11 and 12 are explanatory diagrams for the work of replacing Drain 5 of the existing gutter drainage structure 100P with Drain 1. First, as shown in Figure 11, Drain 5 is removed from the joint 11 (S21). Next, as shown in Figure 12, the cylindrical portion 21 of Drain 1 is inserted into the first cylindrical portion 111 of the joint 11 from the upper side of the gutter 10, through the inlet 10b of the gutter 10 (S22). Then, the male threaded portion 21c of the cylindrical portion 21 engages with the female threaded portion 111c of the first cylindrical portion 111. From here, as Drain 1 is rotated relative to the joint 11, the flange 22 of the drain pipe portion 2 eventually hits the upper surface of the peripheral edge of the inlet 10b of the bottom wall 10a of the gutter 10 at its second surface 22b. In this way, the drain 1 and the joint 11 are attached to the gutter 10 by sandwiching the periphery of the inlet 10b in the gutter 10 from both the top and bottom.

[0098] Thus, drain 1 can replace the existing drain 5, which has a cylindrical section 61 with the same outer diameter as the cylindrical section 21. By replacing it with drain 1, inlet losses can be reduced and the flow rate can be improved. When replacing drain 5 with drain 1, the fitting 11 can be used as is, so there is no need to remove the fitting 11 from the gutter 10. Normally, the fitting 11 is fixed between the gutter 10 and the piping member with adhesive or the like, so it is very difficult to remove. The fact that there is no need to replace the fitting 11 itself makes the replacement work of drain 1 very easy.

[0099] Drains used in gutter drainage structures are generally classified into two main types: normal drainage drains and high-drainage (siphon-utilizing) drains. Normal drainage drains are not designed to withstand full water or two-phase gas-liquid flow with a low void ratio, and normal drainage drains may not adequately reduce inlet losses for siphon use. In recent years, due to the increase in rainfall from torrential downpours and other sources, there has been a demand to improve the drainage capacity of gutter drainage structures. In particular, there is a growing need to address the recent increase in rainfall by increasing drainage capacity while utilizing existing gutter drainage structures.

[0100] When upgrading an existing gutter drainage structure to a high-drainage type, one might consider replacing the standard drain with a high-drainage drain. However, this involves replacing the standard drain and its fitting with a high-drainage drain and its fitting. The fitting is fixed with adhesive between the gutter and the piping component, and removing the fitting would require dismantling at least a portion of the gutter drainage structure, which is impractical. However, in this embodiment, drain 1 can reuse the fitting 11 of drain 5, allowing the fitting to be shared between standard and high-drainage applications, thus improving the efficiency of parts utilization. Furthermore, since there is no need to dismantle the gutter drainage structure to remove the fitting, the installation work becomes extremely simple.

[0101] The vertical pipe 12 defines the vertical flow path. The vertical pipe 12 is fixed to the wall 220 of the building 200. In a rain gutter system, the vertical pipe 12 is also called a downpipe. The vertical pipe 12 is installed to drain rainwater from the inlet 10b. The vertical pipe 12 allows rainwater from the inlet 10b to flow vertically. The vertical pipe 12 is straight. The cross-section perpendicular to the central axis of the vertical pipe 12 is circular. The vertical pipe 12 is positioned so that the direction of its central axis coincides with the vertical direction. The vertical pipe 12 has an upstream end 12a and a downstream end 12b. The upstream end 12a is the end of the vertical pipe 12 that connects to the inlet 10b (the upper end in Figure 1). The downstream end 12b is the end of the vertical pipe 12 that is inserted into the manhole 310 (the lower end in Figure 1). In Figure 1, a pipe cover 12c is positioned to prevent rainwater from flowing into the manhole 310 through the gap between the vertical pipe 12 and the manhole 310. The length of the vertical pipe 12 is preferably 3m or more.

[0102] The socket 13 connects the fitting 11 and the vertical pipe 12. In this embodiment, the first cylindrical portion 111 of the fitting 11 is connected to the upstream receiving end of the socket 13, and the upstream end 12a of the vertical pipe 12 is connected to the downstream receiving end of the socket 13.

[0103] For example, the material of the vertical pipe 12 and the socket 13 is rigid polyvinyl chloride. The dimensions of the vertical pipe 12, 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". The dimensions of the socket 13, for example, the outer diameter and thickness, may be set in accordance with the standard for sockets of JIS K 6739 "Rigid polyvinyl chloride pipe fittings for drainage".

[0104] [1.2 Effects, etc.] The drain 1 described above comprises a cylindrical portion 21 positioned at the inlet 10b of the bottom wall 10a of the gutter 10, a flange 22 extending outward from the upstream end 21a of the cylindrical portion 21, and a connecting portion 23 located between the upstream end 21a of the cylindrical portion 21 and the flange 22. The connecting portion 23 has a cylindrical reduced-diameter portion 24 whose inner diameter gradually decreases from the flange 22 toward the cylindrical portion 21 until it becomes smaller than the inner diameter Du1 of the cylindrical portion 21 (minimum value) Du2, and an enlarged-diameter portion 25 extending outward from the downstream end 24b of the reduced-diameter portion 24 and connected to the upstream end 21a of the cylindrical portion 21. The inner circumferential surface 241 of the reduced-diameter portion 24 is curved, consisting of one or more arcs in a cross-section passing through the central axis C21 of the cylindrical portion 21. This configuration makes it possible to reduce inlet losses without being constrained by the piping member (socket 13) connected to the gutter 10.

[0105] In drain 1, if Ri [mm] is the representative value of the radius of curvature defining the inner circumferential surface 241 of the reduced diameter portion 24 in the cross-section passing through the central axis C21 of the cylindrical portion 21, then Ri > 10 mm is satisfied. This configuration enables further reduction of inlet loss.

[0106] In drain 1, if D [mm] is the maximum inner diameter of the piping member that can be connected to the inlet 10b, then 0.05D ≤ Ri ≤ 0.20D is satisfied. This configuration allows for further reduction of inlet losses.

[0107] In drain 1, the condition 40 ≤ D ≤ 150 is satisfied. This configuration allows for further reduction of inlet losses.

[0108] In the drain 1, the outer diameter of the reduced-diameter portion 24 gradually decreases from the flange 22 toward the cylindrical portion 21 until it becomes smaller than the outer diameter of the cylindrical portion 21. This configuration can reduce the possibility of sink marks occurring on the outer circumferential surface 242 of the reduced-diameter portion 24.

[0109] In the drain 1, a male threaded portion 21c is provided on the outer circumferential surface of the cylindrical portion 21. This configuration facilitates connection between the drain and other piping components.

[0110] The drain 1 comprises a drain pipe section 2 having a cylindrical section 21, a flange 22, and a connecting section 23; five or more vanes 4 protruding from the upstream end 2a of the drain pipe section 2 in the direction of the central axis C2 of the drain pipe section 2; and a connecting section (funnel section 3) that connects the five or more vanes 4 to each other. This configuration enables improved flow straightening and suppression of deterioration of drainage function caused by foreign matter.

[0111] [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.

[0112] The gutter drainage structure to which the drain 1 described above can be applied is not limited to the gutter drainage structure 100 shown in Figure 1.

[0113] [2.1 Variation 1] Figure 13 is a schematic diagram of the gutter drainage structure 100A according to modified example 1. The gutter drainage structure 100A comprises a drain 1, a gutter 10, a joint 11, a vertical pipe 12, a horizontal pipe 14, a first elbow 15-1, and a second elbow 15-2.

[0114] In the eaves gutter drainage structure 100A, the vertical pipe 12 is connected to the joint 11 via the horizontal pipe 14, the first elbow 15-1, and the second elbow 15-2.

[0115] The horizontal pipe 14 defines a flow path that intersects the vertical direction. In a rain gutter system, the horizontal pipe 14 is also called a connecting pipe. The horizontal pipe 14 is the part that carries rainwater from the building 200 from the inlet 10b to the vertical pipe 12. The horizontal pipe 14 is located between the rainwater inlet 10b and the vertical pipe 12. The horizontal pipe 14 is straight. The cross section perpendicular to the central axis of the horizontal pipe 14 is circular. The horizontal pipe 14 is fixed so that the direction of the central axis of the horizontal pipe 14 is inclined with respect to the up and down direction (vertical direction). The horizontal pipe 14 has an upstream end 14a and a downstream end 14b. The upstream end 14a is the end of the horizontal pipe 14 that connects to the inlet 10b (the left end in Figure 13). The downstream end 14b is the end of the horizontal pipe 14 that connects to the vertical pipe 12 (the right end in Figure 13). For example, the material of the horizontal pipe 14 is rigid polyvinyl chloride. The dimensions of the horizontal pipe 14, for example, the outer diameter and thickness, may be set in accordance with the standard for rigid polyvinyl chloride pipes (general) in JIS K 6741 "Rigid Polyvinyl Chloride Pipes".

[0116] The first elbow 15-1 and the second elbow 15-2 change the direction of the flow path. The first elbow 15-1 and the second elbow 15-2 are connecting fittings that connect flow paths with different directions, such as a vertical pipe and a horizontal pipe.

[0117] Each of the first elbow 15-1 and the second elbow 15-2 has a curved section (bend) 15a and receiving openings 15b and 15c. The curved section 15a and the receiving openings 15b and 15c are formed as a continuous, integral part. As an example, the material of the first elbow 15-1 and the second elbow 15-2 is rigid polyvinyl chloride. The dimensions of the first elbow 15-1 and the second elbow 15-2 may be set in accordance with the JIS K 6739 standard "Rigid polyvinyl chloride pipe fittings for drainage".

[0118] Each of the first elbow 15-1 and the second elbow 15-2 is a 45° elbow (so-called 45L) as specified in JIS K 6739. In each of the first elbow 15-1 and the second elbow 15-2, the angle between the central axes of the sockets 15b and 15c is 45°.

[0119] In the eaves gutter drainage structure 100A, the first cylindrical portion 111 of the joint 11 is connected to the receiving port 15b of the first elbow 15-1, and the upstream end 14a of the horizontal pipe 14 is connected to the receiving port 15c of the first elbow 15-1. The downstream end 14b of the horizontal pipe 14 is connected to the receiving port 15b of the second elbow 15-2, and the upstream end 12a of the vertical pipe 12 is connected to the receiving port 15c of the second elbow 15-2. In this way, a flow path for rainwater from the eaves gutter 10 to the drain basin 310 is formed.

[0120] [2.2 Variation 2] Figure 14 is a schematic diagram of the gutter drainage structure 100B according to the modified example 2. The gutter drainage structure 100B comprises a drain 1, a gutter 10, a joint 11, a vertical pipe 12, and an eccentric socket 16.

[0121] In the eaves gutter drainage structure 100B, the vertical pipe 12 is connected to the joint 11 via an eccentric socket 16.

[0122] The eccentric socket 16 has an eccentric portion 16a and receiving openings 16b and 16c. The eccentric portion 16a and receiving openings 16b and 16c are formed as a continuous, integral part. As an example, the material of the eccentric socket 16 is rigid polyvinyl chloride. The eccentric socket 16 may be a so-called S-socket.

[0123] In the eaves gutter drainage structure 100B, the first cylindrical portion 111 of the joint 11 is connected to the receiving opening 16b of the eccentric socket 16, and the upstream end 12a of the vertical pipe 12 is connected to the receiving opening 16b of the eccentric socket 16. In this way, a flow path for rainwater from the eaves gutter 10 to the manhole 310 is formed.

[0124] [2.3 Variation 3] Figure 15 is a schematic diagram of the gutter drainage structure 100C according to the modified example 3. The gutter drainage structure 100C comprises a drain 1, gutters 10-1 and 10-2, a joint 11, vertical pipes 12-1 and 12-2, horizontal pipes 14-1 and 14-2, first to third elbows 15-1 to 15-3, a tee 17, a drain 18, and a piping member 19.

[0125] The gutter 10-1 receives rainwater from the roof 210 of the building 200. The gutter 10-1 is installed below the roof 210 of the building 200. The gutter 10-2 receives rainwater from a roof or eaves, etc., below the roof 210 of the building 200. For example, the gutter 10-2 is installed below the gutter 10-1.

[0126] Drain 1 is positioned at the inlet 10b of the gutter 10-1.

[0127] Drain 18 is located at the inlet 10b of the gutter 10-2. Drain 18 does not necessarily have the same configuration as drain 1. Drain 18 may have a well-known configuration.

[0128] The vertical pipe 12-1 is connected to the gutter 10-1 (drain 1 installed in the gutter 10-1) via the horizontal pipe 14-1, the first elbow 15-1, the second elbow 15-2, and the piping member 19. The vertical pipe 12-2 is connected to the gutter 10-2 (drain 18 installed in the gutter 10-2) via the horizontal pipe 14-2, the third elbow 15-3, and the tee 17.

[0129] Horizontal pipe 14-1 is located between the eaves gutter 10-1 and the vertical pipe 12-1. Horizontal pipe 14-2 is located between the eaves gutter 10-2 and the vertical pipe 12-2. Here, the length of horizontal pipe 14-1 is 2m or less, preferably 1m or less.

[0130] The first elbow 15-1 connects the gutter 10-1 to the upstream end 14a of the horizontal pipe 14-1. The second elbow 15-2 connects the downstream end 14b of the horizontal pipe 14-1 to the upstream end 12a of the vertical pipe 12-1. The third elbow 15-3 connects the gutter 10-2 to the upstream end 14a of the horizontal pipe 14-2.

[0131] In this modified example, the first elbow 15-1 is a 90° large-bend elbow (so-called LL) as defined in JIS K 6739. The second elbow 15-2 and the third elbow 15-3 are 90° elbows (so-called DL) as defined in JIS K 6739.

[0132] The cheese (Tee) 17 has an upward-facing first receiving port 17a, a downward-facing second receiving port 17b, and a laterally-facing third receiving port 17c. The cheese 17 combines the fluid flowing in from the first receiving port 17a with the fluid flowing in from the third receiving port 17c, and discharges it from the second receiving port 17b. The angle between the central axis of the first receiving port 17a and the central axis of the third receiving port 17c is 90° or less. As an example, the angle between the central axis of the first receiving port 17a and the central axis of the third receiving port 17c is set to 88.83°. As an example, the material of the cheese 17 is rigid polyvinyl chloride.

[0133] The first socket 17a is connected to the downstream end 12b of the vertical pipe 12-1. The second socket 17b is connected to the upstream end 12a of the vertical pipe 12-2. The third socket 17c is connected to the downstream end 14b of the horizontal pipe 14-2.

[0134] In the eaves gutter drainage structure 100C, a first elbow 15-1 and a second elbow 15-2 are provided between the eaves gutter 10-1 and the vertical pipe 12-1. The direction of the flow path changes in each of the first elbow 15-1 and the second elbow 15-2. When the direction of the flow path changes, pressure loss due to separation can be one of the causes of a decrease in flow rate. In this modified example, the radius of curvature of the second elbow 15-2 is smaller than the radius of curvature of the first elbow 15-1. Therefore, the pressure loss caused by the second elbow 15-2 tends to be greater than the pressure loss caused by the first elbow 15-1. To reduce the decrease in flow rate due to the pressure loss caused by the second elbow 15-2, a piping member 19 is provided.

[0135] The piping member 19 is positioned between the second elbow 15-2 and the vertical pipe 12-1. The piping member 19 comprises a straight pipe section 19a and a protruding member 19b.

[0136] The straight pipe section 19a is straight and has a socket 191 at its downstream end. The socket 191 is provided to connect the upstream end 12a of the vertical pipe 12-1 to the straight pipe section 19a. The upstream end of the straight pipe section 19a is connected to the socket 15c of the second elbow 15-2.

[0137] The projection member 19b is located downstream of the second elbow 15-2. More specifically, the projection member 19b is located on the inner circumference of the second elbow 15-2 within the straight pipe section 19a downstream of the second elbow 15-2 and is used to partially reduce the flow path cross-sectional area.

[0138] The surface of the projection member 19b has a curved shape that protrudes from the inner circumference to the outer circumference of the second elbow 15-2. The height of the projection member 19b varies along the direction of the central axis of the vertical pipe 12-1. The projection member 19b has a apex where its height is greatest, located between the upstream end and the downstream end. The height of the projection member 19b increases monotonically from the upstream end towards the apex. The height of the projection member 19b decreases monotonically from the apex towards the downstream end. At the apex, the projection member 19b minimizes the flow path cross-sectional area of ​​the vertical pipe 12-1.

[0139] Thus, by providing the projection member 19b, a reduced portion exists downstream of the second elbow 15-2 where the flow path cross-sectional area is smaller than that of the vertical pipe 12-1. The presence of such a projection member 19b is expected to (1) make it easier for the fluid to flow along the pipe wall than in the absence of the projection member 19b, and (2) reduce the number of areas where pressure loss may occur. Therefore, the projection member 19b can reduce the occurrence of pressure loss due to separation downstream of the second elbow 15-2 and improve the flow rate.

[0140] In the eaves gutter drainage structure 100C, rainwater from the eaves gutter 10-1 flows into the tee 17 through the first elbow 15-1, horizontal pipe 14-1, second elbow 15-2, piping member 19, and vertical pipe 12-1. Similarly, rainwater from the eaves gutter 10-2 flows into the tee 17 through the third elbow 15-3 and horizontal pipe 14-2. The rainwater from the eaves gutter 10-1 and the rainwater from the eaves gutter 10-2 then merge at the tee 17 and are discharged into the manhole 310 through the vertical pipe 12-2.

[0141] [2.4 Modification 4] Figure 16 is a cross-sectional view of the drain 1D according to modified example 4. The drain 1D comprises a drain pipe section 2D, a funnel section 3, and one or more vanes 4.

[0142] The drain pipe section 2D comprises a cylindrical section 21, a flange 22, and a connecting section 23D.

[0143] The connecting portion 23D has a reduced diameter portion 24 and an enlarged diameter portion 25D.

[0144] The enlarged diameter section 25D is cylindrical in shape, with its inner diameter gradually increasing from the reduced diameter section 24 towards the cylindrical section 21. In particular, the inner diameter of the enlarged diameter section 25D gradually increases from the reduced diameter section 24 towards the cylindrical section 21, from a value equal to the minimum value Du2 of the inner diameter of the reduced diameter section 24 to a value equal to the inner diameter Du1 of the cylindrical section 21. The outer diameter of the enlarged diameter section 25D gradually increases from the reduced diameter section 24 towards the cylindrical section 21, from a value equal to the minimum value of the outer diameter of the reduced diameter section 24 to a value equal to the outer diameter of the cylindrical section 21.

[0145] In this modified example, in a cross-section passing through the central axis C21 of the cylindrical portion 21, the inner and outer surfaces of the enlarged diameter portion 25D are straight. However, in a cross-section passing through the central axis C21 of the cylindrical portion 21, the inner and outer surfaces of the enlarged diameter portion 25D may be curved, composed of one or more circular arcs.

[0146] The enlarged diameter section 25D allows the inner diameter to gradually change from the reduced diameter section 24 to the cylindrical section 21, thereby reducing pressure loss.

[0147] [2.5 Other variations] In one modified example, the drain pipe portion 2, the funnel portion 3, and the blade 4 may be formed by injection molding of a resin such as rigid polyvinyl chloride resin, polycarbonate, or ABS, or they may be made of a metal such as cast iron. The drain pipe portion 2, the funnel portion 3, and the blade 4 may be formed as a single continuous part, or they may be formed as separate parts.

[0148] In one modified example, the drain 1 does not necessarily have to have a funnel portion 3. Similarly, the drain 1 does not necessarily have to have vanes 4.

[0149] In one modified example, the drain 1 may be equipped with a funnel portion 7 and a support portion 8 of the drain 5.

[0150] In one modified example, when viewed from the direction of the central axis C3 of the funnel portion 3, the outer shape of the funnel portion 3, for example, the reduced diameter portion 31, the small diameter cylindrical portion 32, or the outer shape of the flange 33, is not limited to a circular shape, but may be elliptical, polygonal, or other shapes.

[0151] In one modified example, the drain 1 does not need to have a funnel portion 3 as a connecting portion. The connecting portion may be a lid portion. The lid portion may be plate-shaped. The lid portion may be circular when viewed from the direction of the central axis of the lid portion. However, the outer shape of the lid portion is not limited to a circular shape, and may be elliptical, polygonal, or other shapes. The thickness of the lid portion may be uniform. It is preferable that the lid portion does not have a hole passing through it in order to function as a lid for the drain opening 2c.

[0152] In one modified example, the funnel portion 3 may not have to have either or both of the small-diameter cylindrical portion 32 and the flange 33.

[0153] In one modified example, the number of blades 4 is not particularly limited. The number of blades 4 may be one or more. The blades 4 may be located between the funnel portion 3 and the connecting portion 23 or flange 22, as long as they do not come into contact with the surface of the funnel portion 3 on the cylindrical portion 21 side (second surfaces 312, 332).

[0154] In one modified example, the arm portion 42 of the blade 4 does not necessarily have to extend to the reduced diameter portion 31. In other words, the arm portion 42 does not have to have a second portion 42b. The height of the second portion 42b relative to the drain pipe portion 2 does not have to decrease as it approaches the center of the reduced diameter portion 31.

[0155] In one modified example, the arm portion 42 of the blade 4 does not necessarily have to be connected to the flange 33, but may be connected only to the reduced diameter portion 31. In other words, the arm portion 42 may be connected to the reduced diameter portion 31 without being connected to the flange 33. In this case, there may be a gap between the first surface 331 of the flange 33 and the arm portion 42 in the direction of the central axis C2 of the drain pipe portion 2.

[0156] In one modified example, the first end portion 41a of the main body portion 41 does not have to be inclined to move away from the funnel portion 3 as it approaches the drain pipe portion 2. Therefore, the first end portion 41a may extend along the central axis C2 of the drain pipe portion 2.

[0157] In one modified example, the gap G may be provided by shortening the length of the main body portion 41 of the blade 4 in the radial direction of the drain pipe portion 2, or by forming a notch in the main body portion 41 on the funnel portion 3 side. In short, the gap G should be provided such that the flange 33 of the funnel portion 3 and the main body portion 41 of the blade 4 are spaced apart from each other in the radial direction of the drain pipe portion 2.

[0158] [3. Appearance] As will be apparent from the above embodiments and modifications, this disclosure includes the following aspects.

[0159] [Aspect 1] A cylindrical section positioned at the inlet of the bottom wall of the gutter, A flange extending outward from the upstream end of the cylindrical portion, A connecting portion located between the upstream end of the cylindrical portion and the flange, Equipped with, The aforementioned connection part is A cylindrical reduced-diameter section, from the flange toward the cylindrical section, whose inner diameter gradually decreases until it becomes smaller than the inner diameter of the cylindrical section, An enlarged diameter portion extends outward from the downstream end of the reduced diameter portion and is connected to the upstream end of the cylindrical portion, It has, The inner circumferential surface of the reduced diameter portion is curved in shape, consisting of one or more circular arcs in a cross-section passing through the central axis of the cylindrical portion. Drain.

[0160] [Aspect 2] If Ri [mm] is a representative value of the radius of curvature that defines the inner circumferential surface of the reduced diameter portion in a cross-section passing through the central axis of the cylindrical portion, then Ri > 10 mm is satisfied. Drain in embodiment 1.

[0161] [Aspect 3] If the maximum inner diameter of the piping member that can be connected to the inlet is D [mm], Satisfying 0.05D ≤ Ri ≤ 0.20D, Drain in embodiment 2.

[0162] [Aspect 4] Satisfying 40 ≤ D ≤ 150, Drain in embodiment 3.

[0163] [Aspect 5] The outer diameter of the reduced diameter portion gradually decreases from the flange toward the cylindrical portion until it becomes smaller than the outer diameter of the cylindrical portion. A drain from any one of the embodiments 1 to 4.

[0164] [Aspect 6] The outer surface of the cylindrical portion is provided with a male screw portion. A drain from any one of the embodiments 1 to 5.

[0165] [Aspect 7] A drain pipe section having the cylindrical portion, the flange and the connecting portion, Five or more blades protruding from the upstream end of the drain pipe in the direction of the central axis of the drain pipe, A connecting portion that connects the five blade-shaped parts, Equipped with, A drain from any one of the embodiments 1 to 6.

[0166] The second through seventh aspects are not mandatory. [Industrial applicability]

[0167] This disclosure is applicable to drains. Specifically, this disclosure is applicable to drainage drains used in gutters. [Explanation of Symbols]

[0168] 1. 1D Drain 2, 2D drain pipe section 2a Upstream end 21 Cylinder part 21a Upstream end 21b Downstream end 21c male thread part 22 Flange 22a 1st page 22b 2nd side 23, 23D connection section 24 Reduced diameter part 24a Upstream end 24b Downstream end 241 Inner surface 242 Outer surface 25, 25D enlarged diameter part 3 Funnel part 4 feathers 10, 10-1, 10-2 Eaves gutter 10a bottom wall 10b Inlet 13 Socket (piping component)

Claims

1. A cylindrical section positioned at the inlet of the bottom wall of the gutter, A flange extending outward from the upstream end of the cylindrical portion, A connecting portion located between the upstream end of the cylindrical portion and the flange, Equipped with, The aforementioned connection part is A cylindrical reduced-diameter section, from the flange toward the cylindrical section, whose inner diameter gradually decreases until it becomes smaller than the inner diameter of the cylindrical section, An enlarged diameter portion extends outward from the downstream end of the reduced diameter portion and is connected to the upstream end of the cylindrical portion, It has, The inner circumferential surface of the reduced diameter portion is curved in shape, consisting of one or more circular arcs in a cross-section passing through the central axis of the cylindrical portion. Drain.

2. If Ri [mm] is a representative value of the radius of curvature that defines the inner circumferential surface of the reduced diameter portion in a cross-section passing through the central axis of the cylindrical portion, then Ri > 10 mm is satisfied. The drain according to claim 1.

3. If the maximum inner diameter of the piping member that can be connected to the inlet is D [mm], Satisfying 0.05D ≤ Ri ≤ 0.20D, The drain according to claim 2.

4. Satisfying 40 ≤ D ≤ 150, The drain according to claim 3.

5. The outer diameter of the reduced diameter portion gradually decreases from the flange toward the cylindrical portion until it becomes smaller than the outer diameter of the cylindrical portion. The drain according to claim 1.

6. The outer surface of the cylindrical portion is provided with a male screw portion. The drain according to claim 1.

7. A drain pipe section having the cylindrical portion, the flange and the connecting portion, Five or more blades protruding from the upstream end of the drain pipe in the direction of the central axis of the drain pipe, A connecting portion that connects the five or more blades, Equipped with, The drain according to claim 1.

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