JP2024057381A - Drainage diffusion material - Google Patents

Abstract

[Problem] To improve strength and durability, and to increase the effect of reducing the impact force of drained rainwater. [Solution] A drainage diffusion member 1 is attached to the tip of a drainage pipe 100, and includes a connection part 10 that connects to the drainage pipe 100, and a cylindrical diffusion part 20 in a truncated cone shape that continues from the connection part 10 and has an inverse tapered shape that expands in diameter downward, and the tip of the diffusion part 20 on the larger diameter side is formed in an alternating uneven shape in the circumferential direction. [Selected Figure] Figure 5

Description

The present invention relates to a drainage diffusion member that is attached to a drainage device that collects rainwater that falls on the bridge surface of a bridge over a river, guides it to the bottom of the bridge, and drains the rainwater by diffusing and dispersing it. In particular, the present invention relates to a drainage diffusion member that can improve strength and durability and reduce the impact force of the drained rainwater.

On bridges built over rivers, catch basins are installed on the sides of the bridge surface, and rainwater that falls on the bridge surface is collected in the catch basins by taking advantage of the slope of the road surface, etc. The rainwater that collects in the catch basins is then guided to the bottom of the bridge by drainage pipes connected to the bottom of the catch basin, from where it falls naturally and is drained away.
However, if rainwater is allowed to fall naturally from the mouth of the drain pipe directly toward the river at the bottom of the bridge, it will fall like a waterfall, concentrated in one specific location. In other words, acceleration due to gravity (gravitational acceleration) will occur, increasing the flow rate and falling speed of the rainwater, and a large dynamic water pressure will be applied to the point where it falls. For this reason, there is a risk that the falling rainwater will cause a large impact on ships passing under the bridge, causing obstruction to the passage of ships, damage to components, and safety concerns.

Therefore, Patent Document 1 proposes attaching an umbrella-shaped water sprinkler member with a gap to the open lower end of a water drop pipe that hangs down from the bottom of a drainage ditch installed on a bridge or the like.

Japanese Utility Model Application Publication No. 5-64209

However, the structure of the sprinkler member described in Patent Document 1 has shallow and deep grooves arranged alternately in the circumferential direction, and is thought to be manufactured by joining corrugated sheets of soft polyvinyl chloride or the like into a ring shape. This makes it time-consuming to manufacture, and it is difficult to ensure the strength and durability required to withstand wind force, making it impractical. Furthermore, with this structure of the sprinkler member, rainwater that falls from the waterfall pipe is straightened and falls in the shallow and deep groove flow paths, so the rainwater tends to fall in a thin, continuous stream. For this reason, there is a limit to how much dynamic water pressure can be reduced at the point where it falls.

The present invention aims to provide a drainage diffusion member that can improve strength and durability and also reduce the impact force of draining rainwater.

The drainage diffusion member of the invention of claim 1 is a diffusion section that is formed continuously from the connection section attached to the tip of the drainage pipe, and is a cylindrical diffusion section with an inverted taper that expands downward, and has alternating concaves and convexes formed in the circumferential direction at the tip (lower end) of the larger diameter side.

The drainage pipes are components of a drainage system that collects rainwater that falls on the bridge surface and directs it to underneath the bridge. They are conduits that direct rainwater collected in a drainage basin to underneath the bridge. Generally, round, oval, square, etc. rigid polyvinyl chloride pipes (also called PVC pipes or PVC pipes) or steel pipes are used.

The above-mentioned connection part is fixedly connected to the drain pipe by inserting it into the tube at the tip side of the drain pipe and attaching it to the tip side of the drain pipe with mounting fixtures such as bolts and nuts. For example, a cylindrical or columnar one such as a circular, elliptical, or square one is used, but from the viewpoint of strength, durability, and light weight, it is preferably formed into a cylindrical shape and a hard polyvinyl chloride pipe (also called a PVC pipe or PVC pipe) is used. The fixed connection of the above-mentioned connection part to the drain pipe is set so that when the connection part is inserted into the drain pipe and fixedly connected to the drain pipe, the lower end of the drain pipe and the diffusion part are separated without contacting each other, and the vertical distance between them is set to, for example, 4.0 to 8.0 cm, preferably 5.0 to 7.0 cm, and more preferably 5.5 to 6.5 cm.

The diffusion section is formed in a generally truncated cone shape (frustum cone) that is continuous with the lower part of the connection section and has an inverse tapered shape with a diameter expanding downward, and the periphery of the tip of the lower part on the larger diameter side is formed with alternating concaves and convexes, so that the periphery of the tip of the lower part forms, for example, a sawtooth shape or a wave shape, etc. This diffusion section is formed from, for example, a thermoplastic resin such as rigid polyvinyl chloride or polyethylene, or a metal such as steel or iron, but is preferably formed from rigid polyvinyl chloride resin from the viewpoints of light weight, cost, weather resistance, etc.
The alternating concave-convex shape is formed by cutting (notching) multiple repeated concave portions along the periphery of the larger diameter side of the approximately truncated cone, and the shape of the convex portion can be, for example, approximately triangular, approximately rectangular, approximately semicircular, etc.

The diffusion portion of the drainage diffusion member of the invention of claim 2 is such that each convex portion forming the alternating unevenness is formed to have a narrow width toward its tip (lower end), and the downward convex portions are narrowed toward their tip (lower end).
As long as the convex portion has a shape narrowing toward the tip, the tip does not have to be sharp, and may be rounded or linear.

The diffusion portion of the drainage diffusion member of the invention according to claim 3 has the alternating concaves and convexes forming a sawtooth shape, i.e., the lower peripheral portion forms a sawtooth shape with a narrow width toward the tip.
The above-mentioned sawtooth shape does not necessarily require the tips of the downward protrusions forming the sawtooth shape to be strictly sharp, and may be rounded.

In the drainage diffusion member according to the invention of claim 4, the connection portion and the diffusion portion are formed of a hard polyvinyl chloride resin.
The connection portion and the diffusion portion may be made of the same material or a combination of different materials so long as they are integrally continuous. If they are made of the same material, welding for joining them is easy.

In the drainage diffusion member according to the invention of claim 5, the diffusion portion has an outer surface reinforced with fiber reinforced plastic.
As the reinforcing fibers of the fiber reinforced plastic (FRP), various ceramic fibers such as glass fiber, carbon fiber, aramid fiber, silicon carbide fiber, boron fiber, alumina fiber, whiskers, etc. can be used, and as the resin serving as the base material, for example, thermosetting resins such as polyamide resin, epoxy resin, phenol resin, polycarbonate resin, acrylic resin, etc. can be used, and preferably, glass fiber reinforced plastic (GFRP), carbon fiber reinforced plastic (CFRP), etc. can be used. From the viewpoint of cost reduction, etc., glass fiber reinforced plastic (GFRP) is preferably used.
The above-mentioned fiber reinforced plastic is not required to cover the entire outer surface of the diffusion section; it is sufficient that it at least reinforces the area near the point where rainwater falls from the drain pipe, and from the perspective of ease of processing, it may be reinforced above the serrated or wavy tip and may include part or the entire outer surface of the connection section.

The diffusion section of the drainage diffusion member of the invention of claim 6 has a taper ratio of the inverted taper shape that expands in diameter toward the downward direction, which is preferably within the range of 1.0 to 4.0, more preferably 1.2 to 3.5, and even more preferably 1.5 to 3.0.
The taper ratio is a value defined as (M-m)/L, where m is the diameter equivalent to the upper surface of the approximately truncated cone shape of the diffusion part, i.e., the minimum diameter (diameter) of the upper end of the cylindrical diffusion part, and M is the diameter equivalent to the bottom surface of the approximately truncated cone shape of the diffusion part, i.e., the maximum diameter (diameter) of the lower end of the cylindrical diffusion part, and L is the height of the approximately truncated cone shape of the diffusion part, i.e., the vertical length in the up-down direction of the cylindrical diffusion part.

The diffusion section of the drainage diffusion member of the invention of claim 7 has downward protrusions each formed narrow toward the tip, and when the maximum width of the base end of the protrusion is x, the protruding length of the protrusion is y, the length of the straight line connecting the bottom point of the recess formed between the protrusions and the apex of the protrusion is r, and the angle between the straight line length r and the maximum width x is δ, tan δ = y/x is preferably within the range of 1.0 to 4.0, more preferably 1.5 to 3.5, and even more preferably 1.6 to 3.1.

According to the drainage diffusion member of the invention of claim 1, the diffusion section is formed continuously from the connection section attached to the tip of the drainage pipe and is a cylindrical section having an approximately truncated cone shape with an inverted taper that widens in diameter toward the bottom, and the tip section on the larger diameter side is formed in an alternating uneven shape in the circumferential direction.
Therefore, at the lower part of the connection part which is inserted into the opening at the tip of the drain pipe and attached to the drain pipe, a diffusion part is formed which is a cylindrical shape, approximately a truncated cone, with an inverted taper that expands in diameter downward, so that rainwater falling from the drain pipe can be dispersed by the diffusion part and drained and dropped downward.

In particular, the diffusion section, which is a cylindrical shape of a truncated cone with a reverse taper that expands in diameter downward, has a tip on the larger diameter side that has alternately concaves and convexes along the circumferential direction, and can be formed by, for example, processing a high-strength material such as rigid polyvinyl chloride (PVC) into a cylindrical tube (pipe) of an approximately truncated cone shape, and cutting the tip of the tube into an uneven shape such as a sawtooth or wave shape, making it easy to manufacture and increasing its strength. This makes it possible to improve strength and durability. In addition, the diffusion section has an alternatingly uneven shape such as a sawtooth or wave shape at its tip periphery, and the entire outer surface is flat without any uneven grooves, so that rainwater that falls from the drain pipe runs along the outer surface without being rectified to a specific location, and converges and falls at the convex parts of the tip that are formed in an alternately uneven shape such as a sawtooth or wave shape. Therefore, by dispersing the rainwater on the flat outer surface of the diffusion section and flowing it from top to bottom without rectifying it, it is possible to prevent the rainwater from gathering into thin pieces. In addition, the tip is formed with alternating sawtooth or wavy projections, which allows the rainwater to be dispersed by the projections and fall, preventing the rainwater from falling in a single mass from a specific point. This prevents the rainwater from falling in a continuous stream of thin streams, reduces the dynamic water pressure applied to the point where the rainwater falls, and increases the effect of reducing the falling impact force of the drained rainwater.

According to the drainage diffusion member of the invention of claim 2, each of the convex parts forming the alternating unevenness is formed narrower toward its tip, which allows rainwater to fall smoothly and prevents a large amount of rainwater from falling together even when there is a large amount of rainfall. Therefore, in addition to the effect of claim 1, the effect of reducing the impact force of the drained rainwater can be improved.

According to the drainage diffusion member of the invention of claim 3, the alternating concaves and convexes are sawtooth-shaped, which allows easy cutting and allows easy manufacturing at low cost. In particular, rainwater is collected and allowed to fall at the tips of the bent positions of each convex part that forms the sawtooth shape, effectively preventing rainwater from falling in a lump, allowing the flow of rainwater to be thin and fall intermittently. In addition, it allows rainwater to fall smoothly, and prevents rainwater from falling in a lump, even when there is a large amount of rainfall. Therefore, in addition to the effect of claim 1, the effect of reducing the impact force of the drained rainwater can be further increased.

According to the drainage diffusion member of the invention of claim 4, the connection part and the diffusion part are formed of rigid polyvinyl chloride resin, and therefore have excellent weather resistance, durability, corrosion resistance, flexibility, and light weight, and are easy to process. Therefore, in addition to the effect of claim 1, durability and low cost can be achieved at the same time.

According to the drainage diffusion member of the invention of claim 5, the diffusion section has its outer surface reinforced with fiber-reinforced plastic, so in addition to the effect of claim 4, it is possible to improve strength and durability.

According to the drainage diffusion member of the invention of claim 6, the taper ratio of the downwardly expanding reverse taper shape of the diffusion section is within the range of 1.0 to 4.0, more preferably 1.2 to 3.5, and even more preferably 1.5 to 3.0, so that rainwater can be prevented from falling in a lump. Therefore, in addition to the effect of claim 1, the effect of reducing the impact force of the drained rainwater can be improved.

According to the drainage diffusion member of the invention of claim 7, when the maximum width of the base end of each downward convex part formed narrow toward the tip of the diffusion part is x, the protruding length of the convex part is y, the length of the straight line connecting the bottom point of the concave part formed between the convex parts and the apex of the convex part is r, and the angle between the straight line length r and the maximum width x is δ, tan δ = y/x is in the range of 1.0 to 4.0, more preferably 1.5 to 3.5, and even more preferably 1.6 to 3.1, so that the tip of the convex part is less likely to break and rainwater is less likely to fall in a lump. Therefore, in addition to the effect of claim 2, it is possible to achieve both the strength of the convex part and the reduction of the impact force of the rainwater being drained.

FIG. 1 is a schematic diagram illustrating a state in which a drainage device having a drainage diffusion member according to an embodiment of the present invention is installed on a bridge. Fig. 2(a) is a front view of the drainage diffusion member according to the embodiment of the present invention, and Fig. 2(b) is a right side view of the drainage diffusion member according to the embodiment of the present invention. Fig. 3(a) is a plan view of the drainage diffusion member according to the embodiment of the present invention, and Fig. 3(b) is a bottom view of the drainage diffusion member according to the embodiment of the present invention. Fig. 4(a) is a cross-sectional view of the drainage diffusion member according to the embodiment of the present invention taken along line A-A in Fig. 2(a), and Fig. 4(b) is a perspective view of the drainage diffusion member according to the embodiment of the present invention. Fig. 5(a) is a front view showing a state in which the drainage diffusion member according to the embodiment of the present invention is attached to a drainage device, and Fig. 5(b) is a bottom view showing a state in which the drainage diffusion member according to the embodiment of the present invention is attached to a drainage device. Fig. 6(a) is a front view of another example of a drainage diffusion member according to an embodiment of the present invention, Fig. 6(b) is a front view of another example of a drainage diffusion member according to an embodiment of the present invention, and Fig. 6(c) is a front view of a drainage diffusion member according to a modified example of the embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings. Note that in the embodiments, the same symbols and the same reference numerals in the drawings indicate the same or corresponding functional parts, and therefore, redundant detailed descriptions thereof will be omitted here.

[Embodiment]
As shown in Fig. 1, a drainage diffusion member 1 according to an embodiment of the present invention is attached to the open lower end, i.e., the tip, of a drainage pipe 100 which serves as a flow path for accumulated rainwater in a drainage system that collects rainwater that falls on the bridge surface of a bridge B or the like spanning a river or the sea and leads it to under the bridge B for drainage. The drainage system is configured by providing a drainage basin (not shown) in a gutter on the side of the bridge B or the like, and connecting the drainage pipe 100 to the bottom of the drainage basin, with the drainage diffusion member 1 connected to its lower end.

The drain pipe 100 is generally made of thermoplastic resin such as rigid polyvinyl chloride resin (PVC) or polyethylene resin (PE), and its outer diameter is preferably within the range of 110 to 320 mm, more preferably 140 to 270 mm, its thickness is preferably within the range of 3 to 16 mm, more preferably 4 to 10 mm, and its inner diameter is preferably within the range of 100 to 300 mm, more preferably 125 to 250 mm.

As shown in Figures 2 to 5, the drainage diffusion member 1 of this embodiment is composed of a cylindrical connection part 10 that is inserted into the drainage pipe 100 at its tip and attached to the drainage pipe 100 by means of bolts 41 and nuts 42, and a cylindrical diffusion part 20 that is formed integrally with the connection part 10 and has a generally truncated cone shape that expands downward to a diameter larger than the outer diameter of the drainage pipe 100, forming an inverse tapered shape, with the tip peripheral part of the larger diameter side of the diffusion part 20 being sawtooth-shaped. The back view of the drainage diffusion member 1 appears the same as the front view in Figure 2(a), and the left side view of the drainage diffusion member 1 appears the same as the right side view in Figure 2(a).

The connection part 10 in this embodiment is composed of a cylindrical tube portion 11 and a cover portion 12 that closes the upper opening of the tube portion 11, and the surrounding wall forming the tube portion 11 is formed with a hole 43 through which a bolt 41, such as a cut bolt (long thread, full thread) as a mounting fixture for attachment to the drainage pipe 100, and a nut 42 are inserted.
The holes 43 through which the bolts 41 are inserted are formed in a pair at positions opposing each other across the central axis of the tubular portion 11, and one bolt 41 is inserted into the pair of opposing holes 43. That is, the bolt 41 is inserted so as to penetrate the tubular portion 11 in a direction perpendicular to the longitudinal direction of the tube of the connection portion 10 (in the radial direction).

In addition, the surrounding wall of the cylindrical drainage pipe 100 to which the drainage diffusion member 1 is attached is also provided with a pair of holes (not shown) through which the bolts 41 are inserted, at positions opposite each other across the central axis.
By this, bolts 41 are inserted into a pair of opposing holes 43 provided in the tubular portion 11 of the cylindrical connection part 10 and a pair of opposing holes (not shown) provided in the cylindrical drainage pipe 100 into which the connection part 10 is inserted, i.e., the bolts 41 are inserted so as to penetrate the tubular portion 11 and the drainage pipe 100 in a direction perpendicular to the longitudinal direction of the tube of the connection part 10 (radial direction), and nuts 42 are tightened onto the bolts 41 from the outer peripheral surface side of the drainage pipe 100, thereby connecting and fixing the connection part 10 within the drainage pipe 100.

In this embodiment, as shown in Figure 5, two bolts 41 are inserted into the connection part 10 and the drain pipe 100, and the drain diffusion member 1 is attached by fixing the connection part 10 to the drain pipe 100 with the two bolts. The two bolts 41 inserted into the connection part 10 to attach it to the drain pipe 100 are inserted into the connection part 10 and the drain pipe 100 so as to be perpendicular to each other at positions above and below the longitudinal direction of the tube of the connection part 10 and do not interfere with each other, and are attached to the drain pipe 100 by tightening nuts 42 from the outer periphery side of the drain pipe 100.
That is, in this embodiment, a pair of opposing upper holes 43 through which the upper bolt 41 is inserted and a pair of opposing lower holes 43 through which the lower bolt 41 is inserted are provided in the peripheral wall of the tubular portion 11 of the connection portion 10, so that the number of holes 43 through which the bolts 41 are inserted is four in total, and they are provided at 90° intervals from each other. The same applies to the drain pipe 100.

In this way, when two bolts 41 are inserted perpendicular to each other through holes 43 provided in the tubular portion 11 of the connection part 10 and a hole (not shown) provided in the drainage pipe 100 to attach the drainage diffusion member 1 to the drainage pipe 100, the load is balanced, making it difficult for the drainage pipe 100 or the connection part 10 to be damaged even with long-term use, and the nut 42 is unlikely to loosen, causing the drainage diffusion member 1 to rattle or tilt, and a strong attachment is maintained.
However, when implementing the present invention, the bolts 41 may be fixed using only one bolt 41, or three or more bolts 41. Even when two or more bolts 41 are used, the bolts 41 may be arranged so as to cross each other at a position where they do not interfere with each other, or may be inserted at the same height and parallel to each other to attach to the drain pipe 100. The material of the bolts 41 and nuts 42 is not particularly limited, and for example, metals such as stainless steel that are strong and resistant to rust are used.

The hole 43 in the tube portion 11 through which the bolt 41 is inserted is formed, for example, by processing a through hole such as a round hole, a long hole, or a square hole in a hard polyvinyl chloride resin pipe. The shape of the hole 43 is not particularly limited and may be any of a round hole, a long hole, a square hole, etc. The dimensions of the hole 43 are set, for example, to about φ12 to 20 mm, preferably about φ13 to 15 mm, if it is a round hole, about φ12 to 20 mm x 20 to 40 mm, preferably about φ13 to 15 mm x 25 to 35 mm, if it is a long hole, and about 12 to 20 mm x 12 to 40 mm, preferably about 13 to 15 mm x 13 to 35 mm, if it is a square hole. If the hole 43 is a long hole or a long square hole that is long in the length direction of the tube portion 11, it allows fine adjustment of the mounting position relative to the drain pipe 100. The same dimensions and shape as above are also adopted for the hole (not shown) through which the bolt 41 of the drain pipe 100 is inserted.

Furthermore, the connection part 10 of this embodiment is provided with a lid part 12 that closes the opening at the upper end of the tubular part 11, which has a hole 43 in its peripheral wall through which the bolt 41 is inserted. In this embodiment, the lid part 12 is formed in a generally U-shaped cross section (cylindrical with a bottom), fitted onto the upper end of the tubular part 11, and bonded thereto with an adhesive or the like.
In this manner, by closing the upper end opening of the tubular portion 11 with the lid portion 12 , rainwater falling and descending through the drain pipe 100 is prevented from passing through the inside of the tubular portion 11 .

In this embodiment, the cylindrical tube portion 11 and the lid portion 12 having a substantially U-shaped cross section are formed of hard polyvinyl chloride resin, and they are molded separately, and the lid portion 12 is fitted onto the upper end of the tube portion 11 and fixed together with an adhesive or the like. However, when implementing the present invention, the tube portion 11 and the lid portion 12 formed separately may be resin welded together as long as the upper end of the connection portion 10 is closed. The shape of the lid portion 12 is not limited to the above, and it may be substantially disc-shaped, or may be formed substantially T-shaped and inserted into the upper end opening of the tube portion 11 to fit. Furthermore, the tube portion 11 and the lid portion 12 may be molded as a single unit. Note that the connection portion 10 is preferably cylindrical from the standpoints of lightness, cost, and strength, but when implementing the present invention, it may be formed into a columnar, square tube, or square column shape.

The tubular portion 11 of the cylindrical connection portion 10, which is inserted into the tubular drainage pipe 100 and attached by the bolt 41 and nut 42 attachment, preferably has an outer diameter in the range of 25 to 220 mm, more preferably 45 to 170 mm, and even more preferably 45 to 150 mm, a thickness in the range of 1.5 to 15 mm, more preferably 3 to 12 mm, and even more preferably 4 mm to 10 mm, and an inner diameter in the range of 20 to 205 mm, more preferably 40 to 155 mm, and even more preferably 40 to 135 mm. The dimensions and shape of the drainage diffusion member 1 are set according to the inner diameter of the drainage pipe 100 to which it is attached. The outer diameter of the tubular portion 11 is preferably 0.2 to 0.8 times, more preferably 0.3 to 0.7 times, and even more preferably 0.4 to 0.6 times the inner diameter of the drainage pipe 100 to which it is attached. Within this range, installation stability and strength can be ensured without causing stagnation of drained rainwater.

A cylindrical diffusion portion 20 having a generally truncated cone shape is formed continuously from the lower portion of the tube portion 11 on the opposite side of the lid portion 12 of the connection portion 10 .
In this embodiment, the cylindrical diffusion part 20 having a substantially truncated cone shape and the cylindrical connection part 10 are both made of hard polyvinyl chloride resin, and are resin-welded together to form an integral body. The cylindrical diffusion part 20 having a substantially truncated cone shape and the cylindrical connection part 10 are concentric with each other, and are also attached to the drain pipe 100 in a substantially concentric manner.

The diffusion section 20 of this embodiment is a hollow, generally truncated cone with no top or bottom, with an inverted tapered cone surface that widens downward, and the periphery of its lower end forms a zigzag (jagged) sawtooth shape with straight lines repeatedly bending left and right at angles set at regular intervals. That is, the lower end of the diffusion section 20 forms a sawtooth shape by forming protruding sawtooth sections 21 at regular intervals in the circumferential direction as convex sections that narrow toward the tip.

The diffusion section 20 gradually expands in diameter from the diameter of the tube section 11, and the maximum diameter M of its lower end is larger than the diameter of the drain pipe 100. The maximum diameter M of the outer diameter of the lower end of the diffusion section 20 is preferably within the range of 1.4 to 4.0 times, more preferably 1.5 to 3.5 times, and even more preferably 1.6 to 2.5 times the outer diameter of the drain pipe 100, and is within the range of 3.0 to 6.0 times, preferably 3.5 to 5.5 times, and more preferably 4.0 to 5.0 times the minimum diameter m of the upper end outer diameter of the diffusion section 20, which is equal to the outer diameter of the tube section 11. If the expansion of the diffusion section 20 is too large, the flow rate of the water falling from the drain pipe 100 can be reduced, but the rainwater droplets (raindrops) tend to gather (aggregate), and the rainwater tends to fall together. On the other hand, if the expansion of the diffusion section 20 is too small, the flow rate of the rainwater is difficult to decrease, and the strong rainwater falls together. Within the above range, the force of the rainwater falling from the drain pipe 100 can be reduced, preventing the rainwater from falling in a continuous stream, and the impact force of the rainwater being drained can be more effectively reduced.

Here, the taper of the diffusion section 20, which is inverted and widens toward the lower end, is shown in Fig. 6(a) for a relatively large taper angle, in Fig. 6(b) for a small taper angle, and in Fig. 2 to Fig. 5 for intermediate tapers. The inventors conducted extensive experimental research by producing various drainage diffusion members 10 in which the maximum diameter M and minimum diameter m of the diffusion section 20 were constant and only the length L of the diffusion section 20 was changed, with respect to the inclination of the taper of the diffusion section 20 being represented by m, the maximum diameter M of the diffusion section 20 at the lower end, and L (see Fig. 2(a)). When the taper ratio λ = (M-m)/L of the diffusion section 20 is too large, the flow rate of rainwater falling from the drain pipe 100 can be reduced, but the rainwater droplets (raindrops) tend to gather (aggregate), and the rainwater tends to fall in a collected state. On the other hand, even if the taper ratio is too small, the steep inclination of the diffusion section 20 makes it difficult for the water flow rate (falling speed) to decrease, and strong rainwater falls in a lump. If the taper ratio λ = (M-m)/L of the diffusion section 20 is preferably within the range of 1.0 to 4.0, more preferably 1.2 to 3.5, and even more preferably 1.5 to 3.0, it is possible to suppress the force of the rainwater falling from the drain pipe 100 and prevent the rainwater from falling in a lump, and it is possible to increase the effect of weakening the impact force of the rainwater falling from the diffusion section 20.

In terms of the angle between the connection portion 10 and the diffusion portion 20, if the angle θ between the outer edge of the tubular portion 11 and the outer edge of the diffusion portion 20 when viewed from the front as shown in Figure 2 (a) is preferably within the range of 100° to 170°, more preferably 110° to 160°, even more preferably 120° to 150°, and particularly preferably 130° to 140°, this can suppress the momentum of the water falling from the drainage pipe 100 and prevent the rainwater from falling in bulk, thereby enhancing the effect of weakening the impact force of the rainwater falling from the diffusion portion 20.
In terms of the taper angle of the diffusion section 20, if it is within the range of preferably 10° to 80°, more preferably 20° to 70°, even more preferably 30° to 60°, and particularly preferably 40° to 50°, it is possible to reduce the force of the water falling from the drainage pipe 100 and prevent the rainwater from falling in a lump, thereby increasing the effect of weakening the impact force of the rainwater falling from the diffusion section 20.

Then, at the lower end of the diffusion section 20, which is a cylindrical shape with a roughly truncated cone, the sawtooth section 21, which is a number of protrusions formed by cutting a number of recesses into the annular periphery, has a shape that gradually narrows toward the tip, so that rainwater that falls from the drain pipe 100 into the diffusion section 20 flows from above to below on the outer surface of the diffusion section 20 and is converged (collected) at the sawtooth section 21, from which the rainwater falls. The narrow tip of the sawtooth section 21 may be sharp or rounded (R).

According to the inventors' experimental research, the angle α of the tip of the sawtooth portion 21, which is gradually narrowed toward the tip, is preferably in the range of 30° to 85°, more preferably 35° to 80°, and even more preferably 40° to 60° (see FIG. 2(a)). If the angle is too large, the number of sawtooth portions 21 will be reduced, so that the water falling from the drain pipe 100 will have less dispersion effect around the annular periphery of the diffusion portion 20, and the water will be more likely to form a film on the sawtooth portions 21, making it easier for the rainwater to fall in a continuous stream. On the other hand, if the angle is too small, the tip will be sharp and easily damaged. If the angle is within the above range, an appropriate number of sawtooth portions 21 can be formed around the annular periphery of the diffusion portion 20, so that the dispersion and dispersion effect of the rainwater falling from the drain pipe 100 around the annular periphery of the diffusion portion 20 is high, and the rainwater can be prevented from falling in a concentrated stream from the sawtooth portions 21, and the effect of weakening the impact force of the rainwater falling from the diffusion portion 20 can be increased. Furthermore, the tip of the sawtooth portion 21 is not too narrow, which makes it easy to manufacture and ensures strength and durability that makes it difficult to break.

Considering the angle β of the valley between the adjacent sawtooth portions 21 that form the sawtooth shape of the lower end of the diffusion section 20, the angle δ is preferably in the range of 30° to 85°, more preferably 35° to 80°, and even more preferably 40° to 60° (see FIG. 2(a)). Within this range, an appropriate number of sawtooth portions 21 can be formed around the annular circumference of the diffusion section, and the dispersion and dispersion effect of rainwater falling from the drain pipe 100 around the annular circumference of the diffusion section 20 can be high, and rainwater can be prevented from falling in a lump from the sawtooth portions 21, which increases the effect of weakening the impact force of rainwater falling from the diffusion section 20. Furthermore, the ease of cutting the recesses can be ensured.

In addition, the angle α of the tip of the sawtooth portion 21 refers to the angle formed by the intersection of two adjacent sides when the tip of the sawtooth portion 21 as a downward-protruding convex portion (mountain portion) is angular, but when the tip of the sawtooth portion 21 as a convex portion is rounded in an R-shape, the angle α refers to the angle formed by the intersection of imaginary lines that connect in a straight line the center of the apex of the convex portion and the center of the bottom point of the valley of the concave portion (valley portion) between the adjacent convex portions (sawtooth portions 21).
Similarly, the angle β of the valley of the recess between adjacent convex portions (saw-tooth portions 21) indicates the angle formed by the intersection of two adjacent sides when the recess is angular, but when the recess (valley portion) has a rounded R-shape, the angle is the angle formed by the intersection of imaginary lines that connect in a straight line the center of the bottom point of the recess and the center of the apex of the tip of the adjacent convex portion (saw-tooth portion 21).
In addition, in order to ensure ease of cutting, handling, and strength, the apexes of the convex portions (saw-tooth portion 21) and the bottoms of the concave portions are usually machined to have an R shape.

If the sawtooth portion 21 is expressed as a substantially triangular shape that narrows toward the tip (see FIG. 2(a)), the base of the convex portion (sawtooth portion 21) is x, the height connecting the base x and the apex of the convex portion (sawtooth portion 21) is y, the hypotenuse connecting the bottom point of the concave portion (valley portion) between the apex of the convex portion (sawtooth portion 21) and the adjacent convex portion (sawtooth portion 21) is r, and the angle between the hypotenuse r and the base x is δ, then tan δ = y/x is in the range of 1.0 to 4.0, more preferably 1.5 to 3.5, and even more preferably 1.6 to 3.1. If the value is too small, the number of sawtooth portions 21 will be reduced, so that the water that falls from the drain pipe 100 will have less dispersion effect around the annular periphery of the diffusion portion 20, and the water will easily form a film on the sawtooth portion 21, making it easier for rainwater to fall in a continuous stream. On the other hand, if the value is too large, the tip will be sharp and prone to breakage. Within the above range, an appropriate number of sawtooth portions 21 can be formed around the annular circumference of the diffusion section 20, which increases the dispersibility and dispersion effect of rainwater falling from the drain pipe 100 around the annular circumference of the diffusion section 20. Also, rainwater can be prevented from falling in a lump from the sawtooth portions 21, which increases the effect of weakening the impact force of rainwater falling from the diffusion section 20. Furthermore, the tip of the sawtooth portion 21 is not too narrow, which makes it easy to manufacture and ensures strength and durability that are resistant to breakage.

The protruding length (height) y of the sawtooth portion 21 as a convex portion is preferably within a range of 20 to 80 mm, more preferably 25 to 70 mm, even more preferably 30 to 60 mm, and particularly preferably 35 to 45 mm. If the protruding length y of the sawtooth portion 21 is too short, water is likely to form a film on the sawtooth portion 21, and rainwater is likely to fall from the sawtooth portion 21 in a continuous stream. On the other hand, if the protruding length y of the sawtooth portion 21 is too long, water from the sawtooth portion 21 is likely to fall in a continuous stream in a thin stream. If it is within the above range, rainwater can be prevented from falling from the sawtooth portion 21 in a continuous stream, and the effect of weakening the impact force of rainwater falling from the diffusion portion 20 can be enhanced.
In addition, the protruding length (height) y of the sawtooth portion 21 can also be referred to as the depth of the cut or the depth of the valley, since it is manufactured by cutting the peripheral portion of the lower end of the diffusion section 20 to form an uneven sawtooth shape.

The number of the sawtooth portions 21 that form a sawtooth shape in the circumferential direction at the lower end of the diffusion section 20 is preferably in the range of 10 to 40, more preferably in the range of 15 to 35, and even more preferably in the range of 20 to 30. If the number of sawtooth portions 21 is too small, the water that falls from the drain pipe 100 is less dispersible and less effective around the annular periphery of the diffusion section 20, and the water tends to fall in a continuous stream. On the other hand, if the number of sawtooth portions 21 is too large, cutting work is required, and the tip of the sawtooth portion 21 is sharpened, so that the tip is easily damaged. If the number is within the above range, an appropriate number of sawtooth portions can provide high dispersibility and dispersion effect of the water that falls from the drain pipe 100 around the annular periphery of the diffusion section 20, and the moderate acute angle can prevent the rainwater from falling in a concentrated stream, resulting in a weak dynamic water pressure, which can enhance the effect of weakening the impact force of the rainwater falling from the diffusion section 20. In addition, the tip is not too narrow, which makes it easy to manufacture and ensures strength and durability that makes it difficult to break.

In the diffusion section 20 of this embodiment, as shown in Figs. 1 to 5, 6(a) and 6(b), the sawtooth portions 21, which are multiple protrusions that form a sawtooth shape on the peripheral edge of the tip, are uniformly formed with the same dimensions and shape at equal intervals, making cutting, i.e., manufacturing, easier. However, when implementing the present invention, the sawtooth shape may also be achieved by alternately forming sawtooth portions 21 of different dimensions and shapes, for example, as shown in Fig. 6(c).

In this embodiment, the drainage diffusion member 1, which is composed of the cylindrical connection portion 10 and the cylindrical diffusion portion 20 having a substantially truncated cone shape, is made of rigid polyvinyl chloride resin. Furthermore, in this embodiment, the outer peripheral surface of the rigid polyvinyl chloride resin is reinforced with fiber reinforced plastic (FRP) made by compounding fibers such as glass fiber with resin such as epoxy resin or phenolic resin. This can further increase the strength and improve durability. From the viewpoint of reducing costs, it is preferable to use glass fiber reinforced plastic (GFRP).
In Fig. 2(a), for the sake of convenience, the fiber-reinforced plastic (FRP) processed portion is shown in a gray area. In this embodiment, FRP reinforcement is performed on the outer peripheral surface side of the lower part of the tubular part 11 of the connection part 10 and the range from the upper part of the diffusion part 20 connected thereto to above the sawtooth part 21. Therefore, in addition to being able to increase the strength, it is also possible to form a rougher surface than the rigid polyvinyl chloride resin surface by painting the FRP reinforcing layer on the outer peripheral surface, and the rough surface of the FRP reinforcing layer is expected to have the effect of reducing the flow rate of rainwater falling from the drainage pipe 100.
When implementing the present invention, the inner circumferential surfaces of the connection portion 10 and the diffusion portion 20 can also be processed with fiber reinforced plastic (FRP).

Thus, in this embodiment, the diffusion section 20 that receives the rainwater that falls from the drain pipe 100 is a cylindrical shape with a roughly truncated cone shape that expands from top to bottom, and the peripheral portion of the tip on the larger diameter side is sawtooth-shaped. That is, although the lower end peripheral portion of the diffusion section 20 is sawtooth-shaped, the conical surface of the outer surface is flat with no uneven grooves. As a result, the rainwater that falls from the drain pipe 100 is diffused in the diffusion section 20 and falls downward from the tip of the sawtooth portion 21, which acts as a convex portion that forms the sawtooth shape of the lower end peripheral portion.

In this embodiment, the outer surface of the diffusion section 20 is flat and has no concave or convex grooves, so that rainwater that falls from the drain pipe 100 flows from above to below along the outer surface of the diffusion section 20 without being diffused and straightened by the diffusion section 20. The lower peripheral edge of the diffusion section 20 is formed in a sawtooth shape, so that rainwater that flows from above to below along the outer surface of the diffusion section 20 is converged by the sawtooth portion 21, which is a convex portion that forms the sawtooth shape of the lower peripheral edge, and falls downward. Therefore, the outer surface of the diffusion section 20 is flat and has no grooves, so that the flow of rainwater does not become too narrow, and the lower peripheral edge of the diffusion section 20 is formed in a sawtooth shape, so that rainwater does not fall in a lump from a specific point.

In other words, according to the drainage diffusion member 1 of this embodiment, the rainwater that falls from the drainage pipe 100 is prevented from flowing together in the diffusion section 20, while the formation of multiple sawtooth sections 21 on the lower peripheral edge disperses the rainwater so that it does not fall together from a specific point, and the sawtooth sections 21 focus the rainwater and allow it to fall intermittently like raindrops from the narrow tip. This makes it possible to reduce the dynamic water pressure applied to the point where the rainwater falls from the diffusion section 20, and to weaken the impact force of the falling rainwater. And because the sawtooth sections 21 focus and allow the rainwater to fall at the lower end of the diffusion section 20, the rainwater can fall smoothly even when there is a large amount of rainfall.

As shown in FIG. 5, the drainage diffusion member 1 of this embodiment configured in this manner is attached to the drainage pipe 100 by inserting the upper cylindrical connection part 10 side into the cylindrical drainage pipe 100 through the opening at the tip of the pipe, inserting bolts 41 into each pair of holes in the cylindrical part 11 of the cylindrical connection part 10 and each pair of holes (not shown) in the cylindrical drainage pipe 100, and tightening nuts 42 onto the inserted bolts from the outer peripheral surface side of the drainage pipe 100, thereby connecting and fixing the connection part 10 inside the drainage pipe 100.

In this embodiment, two bolts 41 are used and are inserted into a pair of holes 43 in the connection part 10 and a pair of holes (not shown) in the drain pipe 100 at the top and bottom so that they are perpendicular to each other and do not interfere with each other, and then the nuts 42 are tightened, thereby providing strong and stable fixation at two positions, top and bottom, using the bolts 41 and nuts 42. However, when implementing the present invention, as described above, it is possible to install, connect, and fix the bolts and nuts at only one position, or at three or more positions.

The drainage diffusion member 1 is attached to the drainage pipe 100 by inserting the connection part 10 into the drainage pipe 100 and connecting and fixing the connection part 10 to the drainage pipe 100, and the attachment position of the drainage pipe 100 and the connection part 10 is set at a position where the lower end, which is the tip of the drainage pipe 100, and the diffusion part 20 of the drainage diffusion member 1 do not come into contact with each other, and the distance between them in vertical distance is, for example, approximately 4.0 to 8.0 cm, preferably 5.0 to 7.0 cm, and more preferably 5.5 to 6.5 cm.
If the interval is too narrow, it becomes difficult for rainwater to fall smoothly when there is a lot of rainfall, impairing the drainage function. On the other hand, if the interval is too wide, the impact of the water falling from the drain pipe 100 becomes strong, which may damage the drainage diffusion member 1 over long-term use. If the interval is within the above range, water is less likely to stagnate even when there is a lot of rainfall, allowing for smooth drainage, and the drainage diffusion member 1 is less likely to be damaged.

In addition, at the connection part 10 of the drainage diffusion member 1, a lid part 12 is fitted to the upper end of the tubular part 11 to close the upper end opening of the tubular part 11, so that rainwater falling from the drainage part 100 does not enter the inside of the tubular part 11.

In this way, in a drainage device installed on a bridge B that spans a river or the sea, rainwater that falls on the bridge is collected in a drainage basin (not shown) and falls down the drainage pipe 100. By connecting a drainage diffusion member 1 to the lower end opening of the drainage pipe 100, the rainwater that falls inside the drainage pipe 100 is diffused and dispersed by the drainage diffusion member 1 and drained away.
That is, the falling speed and flow rate of rainwater from the drainage pipe 100 is reduced by colliding with the connection section 10 and the diffusion section 20 of the drainage diffusion member 1, and the rainwater falls after being diffused and dispersed in the radial direction by the diffusion section 20. By dispersing and allowing the rainwater from the drainage pipe 100 to fall by the diffusion section 20, it is possible to prevent the rainwater from the drainage pipe 100 from falling in a concentrated manner at a specific location, which would result in a large dynamic water pressure and impact force being applied to the falling point, and the impact force of the rainwater discharged from the drainage pipe 100 can be reduced.

In detail, the drainage diffusion member 1 is attached to the drainage pipe 100 by inserting the connection part 10 of the drainage diffusion member 1 from the opening at the tip side of the drainage pipe 100 and connecting and fixing the connection part 10 inside the drainage pipe 100 with bolts 41 and nuts 42. The rainwater that falls from the drainage pipe 100 falls into the diffusion part 20, which is a cylindrical diffusion part of a generally truncated cone shape that is formed continuously from the connection part 10 of the drainage diffusion member 1 and has an inverse tapered shape that expands in diameter downward, where it is diffused and dispersed, and falls from the narrow tip of the sawtooth part 21, which is a convex part that forms the sawtooth shape at the tip of the larger diameter side of the diffusion part 20. Therefore, by dispersing and allowing the rainwater that falls from the drainage pipe 100 to fall, the impact force of the rainwater being drained can be reduced.

In particular, the diffusion section 20 of this embodiment has a generally truncated cone-shaped cylindrical outer surface that is flat without any uneven grooves, and the lower end peripheral portion is sawtooth-shaped, so that rainwater that falls from the drain pipe 100 into the diffusion section 20 is dispersed without being rectified to a specific location near the point of fall, and flows along the outer surface, converging at the sawtooth portion 21 that forms the sawtooth shape and falling. In this way, the rainwater can be dispersed on the flat outer surface of the diffusion section 20 without being rectified, and can flow from top to bottom, so that the rainwater can be prevented from converging into thin pieces and the flow rate of the rainwater can be suppressed. In addition, the lower end portion is sawtooth-shaped, so that the rainwater that has flowed along the outer surface of the diffusion section 20 can be dispersed by the sawtooth portion 21 and dropped, which can also suppress the rainwater from falling into a congregated state and the flow rate.
Therefore, the drainage diffusion member 1 of this embodiment can reduce the dynamic water pressure applied to the drop point of the rainwater falling from the diffusion section 20, and can enhance the effect of reducing the impact force of the drained rainwater. Therefore, it is possible to reduce the impact and influence that the rainwater drained from the drainage device gives to ships and the like passing under the bridge.

The drainage diffusion member 1 of this embodiment prevents the drained rainwater from falling in a continuous stream of fine droplets and allows the rainwater to fall at a reduced flow rate, which is highly effective in reducing the impact force caused by the falling rainwater. This makes it possible to increase the diameter of the drainage pipe 100 of a conventional drainage device to increase the amount of drainage, and also reduces the number of drainage pipes and construction costs. Even if the amount of drainage from the drainage pipe 100 is increased in this way, the impact and effect of the rainwater drained from the drainage device on ships and other objects passing under the bridge can be reduced.

In the drainage diffusion member 1 of this embodiment, the diffusion section 20 is cylindrical and has an approximately truncated cone shape with a reverse taper that widens in diameter toward the bottom, and the peripheral portion on the lower end side is uneven and serrated. Therefore, the drainage diffusion member 1 can be manufactured, for example, by processing a high-strength material such as rigid polyvinyl chloride (PVC) or polyethylene (PE) into a cylindrical tube (pipe) having an approximately truncated cone shape, and then cutting the tip of the tube to create an uneven and serrated shape.
Therefore, the manufacturing is easy and the strength and durability are high.

In the above embodiment, the drainage diffusion member 1 is attached by inserting its connection part 10 into the lower end opening of the drainage pipe 100, passing the bolt 41 through the connection part 10 and the drainage pipe 100, and tightening the nut 42 onto the bolt 41 from the outer peripheral surface side of the drainage pipe 100, thereby connecting and fixing the connection part 10 to the drainage pipe 100. However, when implementing the present invention, the method of attaching and fixing the drainage diffusion member 1 to the drainage pipe 100 is not limited to the above, and it is also possible to attach it, for example, by using an interlocking structure.

In the above embodiment, the drainage diffusion member 1 is described as being made of rigid polyvinyl chloride resin, but when implementing the present invention, it may be made of other thermoplastic resins such as polyethylene resin, or it may be made of stainless steel, iron, steel, etc.

Furthermore, in the above embodiment, the diffusion section 20 of the drainage diffusion member 1 is described as being saw-toothed, formed of a plurality of sawtooth sections 21 by cutting the peripheral section on the tip side in a zigzag (jagged) shape. In Figs. 2 to 6, the sawtooth section 21 is narrowed toward the tip (downward) and the straight line forming the mountain section is bent at only one point (vertex), and the concave section (valley section) between adjacent sawtooth sections 21 is narrowed toward the valley bottom side (upward) and the straight line forming the concave section is bent at only one point (valley bottom). However, when implementing the present invention, the shape is not limited to a sawtooth shape as long as it is uneven in the circumferential direction, that is, the tip peripheral section is not limited to a straight zigzag (jagged) shape, but may be wavy by forming a zigzag in a curved shape, or may have two bends on the tip side. However, if the sawtooth shape is cut in a straight zigzag (jagged) shape, it is easy to cut and easy to manufacture. In addition, if the convex parts (sawtooth parts 21) are formed to narrow toward the tip (downward) like sawtooth, and the concave parts (valley parts) are formed to narrow toward the bottom of the valley, rainwater can be prevented from falling in a lump, and can be made to converge at the tip and fall intermittently like raindrops.

As described above, the drainage diffusion member 1 of the above embodiment is a drainage diffusion member 1 that is attached to the tip of the drainage pipe 100, and comprises a connection portion 10 that is connected and fixed to the drainage pipe 100, and a cylindrical diffusion portion 20 that is continuous with the connection portion 10 and has a truncated cone shape that forms an inverted taper shape that widens in diameter downward, and the tip portion of the diffusion portion 20 on the larger diameter side is formed in an alternating uneven shape in the circumferential direction.
Therefore, at the lower part of the connection part 10, which is inserted into the opening at the tip of the drainage pipe 100 and attached to the drainage pipe 100, a diffusion part 20 is formed which is a cylindrical shape having an approximately truncated cone shape and an inverted taper that expands in diameter downward, so that rainwater falling from the drainage pipe 100 can be dispersed by the diffusion part 20 and drained and fallen downward.

In particular, the diffusion section 20, which is a cylindrical shape of a truncated cone with a reverse taper that expands in diameter downward, has a tip on the larger diameter side that has alternately concaves and convexes along the circumferential direction, and can be formed by, for example, processing a high-strength material such as rigid polyvinyl chloride (PVC) into a cylindrical tube (pipe) of an approximately truncated cone shape, and cutting the tip of the cylindrical shape into an uneven shape such as a sawtooth or wave shape, making it easy to manufacture and increasing its strength. Thus, it is possible to improve strength and durability. In addition, the diffusion section 20 has an alternatingly uneven shape such as a sawtooth shape at its tip periphery, and the entire outer surface is flat without any uneven grooves, so that rainwater that falls from the drain pipe 100 runs along the outer surface without being rectified to a specific location near the point of fall, and converges and falls at the sawtooth portion 21 as a convex portion of the tip that is formed in an alternatingly uneven shape such as a sawtooth shape. Therefore, by dispersing the rainwater on the flat outer surface of the diffusion section 20 without straightening it and letting it flow from top to bottom, it is possible to prevent the rainwater from integrating into thin streams. Also, by forming an alternating sawtooth or wave-like unevenness at the tip, the rainwater can be dispersed and dropped by the sawtooth section 21 as a convex part, and it is possible to prevent the rainwater from integrating into a single stream and dropping from a specific point. This makes it possible to prevent the rainwater from integrating into thin streams and dropping, making it possible to reduce the dynamic water pressure applied to the drop point of the rainwater, and to increase the effect of reducing the impact force of the rainwater being drained.

According to the above embodiment of the drainage diffusion member 1, the drainage diffusion member 1 is provided with a diffusion section 20 that is formed continuously from the connection section 10 attached to the tip of the drainage pipe 100 and has a generally truncated cone-shaped cylindrical shape with an inverse taper that expands in diameter downward, and the tip on the larger diameter side is sawtooth-shaped around the circumference, and the alternating concaves and convexes form a sawtooth shape, and the sawtooth sections 21 as the convex sections that form the alternating concaves and convexes are formed narrow toward their tips, so that cutting is easy and manufacturing is easy and low cost. In particular, rainwater can be collected and drained at the tips of the bending positions of the convex sections that form the sawtooth shape, so the flow of rainwater is thin and allows for intermittent falling. In addition, it allows rainwater to fall smoothly, and even when there is a lot of rainfall due to heavy rainfall, the flow of rainwater can be prevented from falling in a lump. Therefore, it has a high effect of reducing the impact force of the drained rainwater.

Furthermore, in the drainage diffusion member 1 of the above embodiment, if the taper ratio of the inverse taper shape that expands toward the bottom of the diffusion section 20 is within the range of 1.0 to 4.0, more preferably 1.2 to 3.5, and even more preferably 1.5 to 3.0, rainwater can be better prevented from falling in a lump, further improving the effect of reducing the impact force of the draining rainwater.

In addition, in the drainage diffusion member 1 of the above embodiment, when the maximum width of the base end of each downward convex sawtooth portion 21 formed narrow toward the tip of the diffusion section 20 is x, the protruding length of the sawtooth portion 21 as a convex portion is y, the straight line length connecting the valley bottom point of the concave portion formed between the sawtooth portion 21 as a convex portion and the apex of the sawtooth portion 21 as a convex portion is r, and the angle between the straight line length r and the maximum width x is δ, if tan δ = y/x is within the range of 1.0 to 4.0, more preferably 1.5 to 3.5, and even more preferably 1.6 to 3.1, the tip of the sawtooth portion 21 as a convex portion is less likely to break and rainwater is less likely to fall in a lump. This makes it possible to achieve both the strength of the convex portion and the reduction of the impact force of the rainwater being drained.

In addition, according to the drainage diffusion member 1 of the above embodiment, the connection portion 10 and the diffusion portion 20 are made of rigid polyvinyl chloride resin, which is excellent in weather resistance, durability, corrosion resistance, flexibility, light weight, and easy to process, thereby reducing costs.
Furthermore, according to the drainage diffusion member 1 of the above embodiment, the diffusion section 20 has its outer surface reinforced with fiber-reinforced plastic (FRP), which improves strength and durability. Also, the rough surface of the fiber-reinforced plastic can reduce the flow rate of rainwater.

When implementing the present invention, the configuration and materials of other parts of the drainage diffusion member 1 are not limited to those described in the above embodiment. In addition, the numerical values given in the above embodiment indicate appropriate values suitable for implementation, and slight changes to the numerical values do not negate the implementation.

1 drainage diffusion member 10 connection portion 20 diffusion portion 21 sawtooth portion (convex portion)
100 Drain pipe

Claims (7)

A drainage diffusion member attached to the tip of a drain pipe,
A connection part for connecting to the drain pipe;
a cylindrical diffusion portion having a truncated cone shape that is continuous with the connection portion and expands in diameter downward,
A drainage diffusion member characterized in that the diffusion portion has a tip portion on its larger diameter side formed with alternating concaves and convexes in the circumferential direction. The drainage diffusion member according to claim 1, characterized in that the diffusion section has each of the convex portions forming the alternating concave-convex shape narrowing toward its tip. The drainage diffusion member according to claim 1, characterized in that the alternating unevenness of the diffusion section forms a sawtooth shape. The drainage diffusion member according to claim 1, characterized in that the connection portion and the diffusion portion are made of rigid polyvinyl chloride resin. The drainage diffusion member according to claim 4, characterized in that the outer surface of the diffusion section is reinforced with fiber-reinforced plastic. The drainage diffusion member according to claim 1, characterized in that the diffusion section has a taper ratio in the range of 1.0 to 4.0. The drainage diffusion member according to claim 2, characterized in that the diffusion section has each protrusion formed to have a narrow width toward the tip, and when the maximum width of the base end of the protrusion is x, the protruding length of the protrusion is y, the length of a straight line connecting the bottom point of the recess formed between the protrusions and the apex of the protrusion is r, and the angle between the straight line length r and the maximum width x is δ, the angle is within the range of tan δ = y/x = 1.0 to 4.0.

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