JP2001152539A - Drainage basin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the excavation depth at the execution for burying a drain conduit in the ground not so deep and to prevent the clogging of the drain conduit by the retention of solid materials in drainage. SOLUTION: This drainage basin 23 arranged at the merging point 21 of multiple drainage B1, B2 on a drain conduit 24 buried in the ground is provided with a basin main body 27 fitted with a cleaning port at the upper section, multiple inlet side connection ports 28, 29 provided on the basin main body 27 for connecting multiple inflow side pipes 20, 22a respectively, an outlet side connection port 30 provided on the basin main body 27 for connecting an outflow side pipe 22, and a plate member 34 rockably fitted in the basin main body 27 to guide the drainage B1, B2 flowing in from the inlet side connection ports 28, 29 and to change the flowing direction toward the outlet side connection port 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drainage basin connected to a drainage pipe buried underground, and more particularly to a drainage pit disposed at a junction of a plurality of drains in the drainage pipe.

[0002]

2. Description of the Related Art Wastewater discharged from drainage sources such as baths in kitchens, sinks in kitchens, washrooms, washing machines, toilets, etc., flows through drainage inflow pipes buried underground in residential lands, and a plurality of flows are generated. After merging in the house yard set up at the junction, it flows through the main drainage pipe. Next, the wastewater flows through a public basin installed inside or outside the residential land and a drainage outflow pipe connected to the public basin, and then flows into a public sewer main outside the residential land. The in-house measure is a measure that is installed in a residential area and has an invert portion having various structures, and a trap may be provided as necessary. The public square is a final square that is installed inside or outside the residential land and is used to drain drainage from the residential land into a sewer main outside the residential land. Drainage basins called public basins and installation basins are also a type of house basin, and all are generally called drainage basins. These drainage basins are made of hard synthetic resin such as polyvinyl chloride. ing.

FIG. 6 (A) is a front sectional view showing a state where a conventional drainage basin is installed, and FIG. 6 (B) is a plan view of FIG. 6 (A). The drainage basin 1 shown in FIG. 6 is disposed at a junction 3 of a plurality of drainages in a drainage pipe 2 buried underground. Since the drainage basin 1 is provided for each drainage source,
A plurality of junctions 3 are set in the residential land. A drainage inflow pipe 6 and an upstream drainage main pipe 7 are connected to the inlet connection ports 4 and 5 of the drainage basin 1, respectively, and a downstream drainage main pipe 9 is connected to the outlet connection port 8. This drainage basin 1
Since a step is not formed at the bottom 10, when the drainage pipe 2 including the drainage basin 1 is installed, the bottom surface 11 of the excavated groove is positioned with respect to the horizontal reference plane E so that the drainage naturally flows down. To have a predetermined gradient θ. Since there is no need to provide a step on the bottom surface 11 of the groove, even if the drainage basin 1 is provided at each of the plurality of junctions 3 in the residential land, the excavation depth at the time of construction is not so large.

[0004]

However, the wastewater discharged from the sink and the wastewater discharged from the toilet (sewage containing human waste, etc.) often contain solid matter.
When the wastewater containing solids flows into the drainage basin 1 from, for example, the drainage inflow pipe 6, it may collide with the inner wall of the basin body and a part thereof may flow backward to another inflow port, that is, the direction of the upstream drainage main pipe 7. . The solids in the drained water that has flowed back
3 tends to stay gradually. In particular, in the case of the drainage pipe 2 in which the flow rate and the number of times of the drainage flowing through the upstream drainage main pipe 7 are small due to the layout of the house or the like, such stagnation is repeated or the drainage flow flowing through the upstream drainage main pipe 7 If the solid matter is caught by the stagnation material 13 at the inflow port, the flow path gradually narrows, and there is a possibility that the drainage pipe 2 will eventually be clogged.

FIG. 7A is a front sectional view showing a state where another conventional drainage basin 16 is installed, and FIG. 7B is a plan view of FIG. 7A. In order to prevent the backflow phenomenon of the drainage,
In the drainage basin 16 shown in FIG. 7, a step is provided in the bottom part 17 to make the downstream side lower. By doing so, the drainage containing the solid matter is less likely to flow back to another inflow port, so that it is possible to prevent the drainage line 2 from being clogged due to the stagnation of the solid matter. However, since the bottom 17 of the drainage basin 16 has a step, the step H corresponding to the step of the drainage basin 16 must be formed also on the bottom surface 11 of the trench excavated when the drainage pipe 2 is buried in the ground. No. Thus, the bottom surface 11 of the groove has to be provided with a predetermined gradient θ with respect to the horizontal reference plane E, and it is necessary to excavate further deeply by the step H at each drainage basin 16 at the junction 3. As a result, the digging depth when constructing the drainage pipe 2 becomes gradually deeper toward the downstream side, so that the digging amount increases and digging work becomes difficult. In particular, in the drainage pipe 2 having a large number of junctions 3, the excavation depth on the downstream side may be extremely deep. If the drain pipe 2 becomes lower than the height of the public sewer main, it is necessary to separately install equipment such as a pump for pumping waste water to the public sewer main, which is troublesome.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and the excavation depth at the time of embedding a drainage pipe in the ground is not so deep, and the solid matter in the drainage remains. It is an object of the present invention to provide a drainage basin capable of preventing clogging of a drainage pipe due to the drainage.

[0007]

Means for Solving the Problems In order to achieve the above object, a drainage basin according to the present invention is a drainage basin arranged at a junction of a plurality of drainages in a drainage pipe buried underground. A main body to which a cleaning port is attached at the top, a plurality of inlet-side connection ports provided in the main body for connecting a plurality of inflow-side pipes, and the main body for connecting an outflow-side pipe. An outlet-side connection port provided in the container, and swingably mounted inside the box body to guide drainage flowing from the inlet-side connection port and change the flow direction to the direction of the outlet-side connection port. Provided plate member. It is preferable that the plate member swings freely around a merging point located on the upstream side inside the box body. For example, two or three of the inlet-side connection ports are attached to the box body at an angle of 180 ° or less from each other, and the outlet-side connection port is 90 ° to 180 ° with respect to the center axis of the inlet-side connection port. The merging point, which is attached to the box body at an angle of degrees and is the swing center of the plate member, is located at a predetermined position of the box body substantially opposite to the outlet side connection port, and at one of the inlet sides. It is preferable that it is located between a connection port and another of the entrance-side connection ports. As a preferred embodiment, the plate member is oscillated by the flow of the drainage from one of the inlet-side connection ports and is located on the other of the inlet-side connection ports, and at least the solid matter in the drainage is on the other side. The plate member is prevented from flowing backward to the inflow port on the inlet side connection port side, and the plate member oscillates by the drainage flowing from the other inlet side connection port and is located on the one inlet side connection port side. Thus, at least the solid matter in the waste water is prevented from flowing back to the inflow port on the one inlet side connection port side. In addition, the inlet side connection port, the bottom inner surface of the box body and the outlet side connection port have a predetermined gradient with respect to a horizontal reference plane so that the downstream side becomes gradually lower according to the flow of the drainage. Preferably, it is formed. Further, a cylindrical concave portion having a central axis in a direction perpendicular to the horizontal reference plane is provided on an inner surface of the box body, and a cylindrical shape formed on an edge portion of the plate member arranged in the vertical direction. It is preferable that the engaging portion is fitted into the cylindrical recess so that the plate member swings freely in the horizontal direction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a front sectional view showing a state where a drainage basin of the present invention is installed, and FIG.
Is a plan view of FIG. 1, and FIG. 3 is a partially enlarged perspective view of the drainage basin. As shown in FIGS. 1 and 2, drainage discharged from drainage sources such as a bath in a house, a sink in a kitchen, a washroom, a washing machine and a toilet flows through a drainage inflow pipe 20 connected to each drainage source. At the junction 21
a, 22 to join. At the junction 21, a drainage basin 23 is provided for each drainage source. The drainage basin 23 is connected to a drainage inflow pipe 20, an upstream drainage main pipe 22a, and a downstream drainage main pipe 22. The drainage basin 23 may be a drainage basin with a trap.

In the illustrated drainage line 24, drainage B1 discharged from a drainage source such as a sink and a toilet and flowing through a drainage inflow pipe 20 and drainage B2 flowing through an upstream drainage main pipe 22 a flow into a drainage basin 23. Is shown. The wastewater B1 often contains solids S, and the wastewater B2 sometimes also contains solids S. The drainage flowing through the drainage main pipe 22 through the drainage basin 23 passes through a public basin installed inside or outside the residential land, and then flows through a drainage outflow pipe connected to the public basin, and the public sewerage outside the residential land. Merge into main pipe. The sewer main is buried deep underground such as a road outside the residential land. Drainage inflow pipe 20, drainage basin 23, drainage main pipe 22
a, 22, a public basin, a drainage outflow pipe, a public sewer main pipe, and the like constitute a drainage pipe 24. Drainage pipe 24
Is buried underground with a predetermined gradient θ to allow drainage to flow naturally naturally.

Next, the drainage basin 23 will be described. The drainage basin 23 is disposed at a junction 21 of a plurality of drainages B1, B2 in a drainage pipe 24 buried underground. The drainage basin 23 is integrally formed of a hard synthetic resin such as polyvinyl chloride, polypropylene, and fiber reinforced plastic (FRP). The present invention can also be applied to a concrete drainage basin. The drainage basin 23
A cylindrical box body 27 to which a cleaning port 26 is attached at an upper part;
In order to connect a plurality of inflow-side pipes (here, the drainage inflow pipe 20 and the upstream drainage main pipe 22a), the cell body 2 is connected.
7 are connected to outlet pipes (here, the downstream main drain pipe 22) of the outlet side provided for connecting the plurality of (for example, two) inlet-side connection ports 28 and 29 provided in The connection port 30 and the drainage B1 or B2 flowing from the inlet-side connection ports 28 and 29 are guided to change the flow direction to the outlet-side connection port 3.
A plate member 34 is attached to the inside of the box main body 27 so as to be swingable so as to be changed in the direction of 0. Therefore, the drainage basin 23 has two inlets 31 and 32 and one outlet 33. Inlet side connection port 28, 2
9. Bottom inner surface 37 of basin body 27 and outlet side connection port 30
Is formed so as to have a predetermined gradient θ with respect to the horizontal reference plane E so that the downstream side gradually decreases in accordance with the flow order of the drainage water B1 and B2. Thereby, drainage B1,
B2 flows downstream in the drainage basin 23 under natural flow.

A connecting cylinder 35 projecting upward from the box body 27.
Is connected to the main pipe cleaning pipe 36 in a substantially vertical direction. A lid receiving frame located on the ground is attached to the upper end of the main pipe cleaning tube 36, and a lid is detachably attached to the lid receiving frame. The connection tube 35, the main pipe cleaning tube 36, the lid receiving frame and the lid constitute the main pipe cleaning port 26.
The inlet-side connection port 29 and the outlet-side connection port 30 are formed integrally on both sides of the box body 27 so as to face in opposite directions by 180 degrees and have their central axes C1 substantially coincident with each other.
The central axis C1 and the central axis C3 of the inlet side connection port 28 are
It is slightly inclined with a predetermined inclination θ so that the downstream side becomes gradually lower than the horizontal reference plane E. With the drainage basin 23 installed, the central axis C2 of the basin body 27 is oriented substantially perpendicular to the horizontal reference plane E. The inlet side connection port 28 to which the drainage inflow pipe 20 is connected,
It is formed so as to protrude integrally with the box body 27 in a direction substantially 90 degrees away from the central axis C1. That is, the inlet side connection port 29, the outlet side connection port 30 and the inlet side connection port 2
3 are arranged substantially in a T-shape. Inlet connection port 2
The sockets 8 and 29 and the outlet-side connection port 30 are socket-shaped receptacles (or pipe-shaped outlets).
0, upstream drain main pipe 22a, downstream drain main pipe 22
Are fitted and connected to the connection ports 28, 29 and 30, respectively.

The plate member 34 swings freely around an apparent junction F located on the upstream side inside the box body 27 as a swing center. A converging point F serving as a swing center of the plate member 34 is located at a predetermined position of the box body 27 substantially opposed to the outlet side connection port 30 and between the one inlet side connection port 28 and the other inlet side connection port 29. It is located in. The point where the drainage B1 flowing from the inlet 31 and the drainage B2 flowing from the inlet 32 actually merge (the junction) is located in a lower part near the bottom wall of the cell body 27. . The plate member 34 can exhibit the function of a movable rectifying plate that can guide the drainage B1 or B2 flowing from the inlet-side connection port 28 or 29 and change the flow direction to the outlet-side connection port 30. it can. In addition, the shape of the plate member 34 is not particularly limited, but may be a predetermined shape along the inner wall surface of the cell body 27. As described above, the main drain pipe 22a on the upstream side is substantially on the same central axis C1 with respect to the main drain pipe 22 on the downstream side, but the drain inflow pipe 20 is oriented at substantially 90 degrees. Therefore, when the plate member 34 is not provided, the drainage B1 flowing from the inflow port 31 on the one inlet side connection port 28 side and the solid matter S contained therein are drained by the cell body 2
7 collides with the inner wall, and a part thereof
There is a high possibility that the flow will flow back to the inflow port 32 on the 9th side. The drainage B2 flowing from the other inlet-side connection port 29 and the solid matter S contained therein flow straight through the inside of the box body 27, so that the drainage main pipe 22 passes through the outlet 33 on the outlet-side connection port 30 side. Can flow out. Therefore, the possibility that the drainage B2 and a part of the solid matter S flow back into the inflow port 31 on the one inlet side connection port 28 side is relatively small.

In this embodiment, the plate member 34 of the drainage basin 23
When the wastewater B1 flows from one inlet-side connection port 28, it swings as shown by the arrow G and is located on the other inlet-side connection port 29 side, and at least the solid matter S in the wastewater B1 is This prevents backflow into the inflow port 32 on the inlet side connection port 29 side. In addition, the plate member 34 swings as shown by the arrow G due to the drainage B2 flowing from the other inlet side connection port 29, and is located on the one inlet side connection port 28 side,
This prevents at least the solid matter S in the drainage water B2 from flowing back to the inflow port 31 on the one inlet side connection port 28 side. The plate member 34 is made of a metal such as stainless steel or aluminum, or a hard synthetic resin such as polyvinyl chloride, polyethylene, polypropylene, acrylonitrile-butadiene-styrene copolymer (ABS), fiber reinforced plastic (FRP), or polycarbonate. It is integrally formed in a thin plate shape. The surface of the plate member 34 has a smooth shape with few irregularities so that the solid matter S or the like is not caught. The plate member 34 is preferably light in weight so as to be able to swing lightly and smoothly.

As shown in FIG. 1 to FIG.
A cylindrical concave portion 40 having a central axis C4 in a direction perpendicular to the horizontal reference plane E is integrally formed on the inner surface 38 of FIG. Then, the cylindrical engaging portion 41 formed at the edge of the plate member 34 disposed in the vertical direction is
And the plate member 34 swings freely in the horizontal direction as shown by the arrow G. In this way, after integrally forming the basin body 27 and the like, the engaging portion 41 of the plate member 34 is fitted into the cylindrical concave portion 40 from above in the direction of the central axis C4, thereby forming the drainage basin 23. Can be easily assembled. The cylindrical recess 40 has a central axis C4.
The mold can be easily pulled out at the time of forming the drainage basin. Since the plate member 34 swings in the horizontal direction, the plate member 34 can freely and smoothly swing by the action of only the pressure of the drainage without increasing the weight of the plate member 34.

FIG. 4 is a partially enlarged perspective view of another drainage basin 23a according to a modification of the mounting structure of the plate member 34. In the drainage basin 23a shown in FIG. 4, a support member 42 for supporting the plate member 34 is fixed to the inner surface 38 of the basin body 27a with an adhesive or the like. The support member 42 may be a vertically long integral member. However, in this drainage basin 23a, the drainage basin 23a
In order to reduce the weight of the device, two support members 42 are arranged at the upper portion and the lower portion, respectively. The support member 42 has a cylindrical recess 4 having a central axis C4 in a direction perpendicular to the horizontal reference plane E.
0a. The plate member 34 is provided in the cylindrical concave portion 40a.
Is fitted, the plate member 34 can freely swing in the horizontal direction as shown by the arrow G.

In FIG. 1 to FIG. 4, when the drainage pipe 24 including the drainage basin 23 or 23a is buried in the ground, the bottom surface 11 of the groove for arranging the drainage pipe 24 is positioned on the horizontal reference plane E. On the other hand, a trench having a predetermined gradient θ is excavated. In the drainage line 24 thus installed,
When the drainage B1 and the solid matter S discharged from the sink, the toilet, etc., flow through the drainage inflow pipe 20 and flow into the inside of the drainage basins 23, 23a from one of the inlets 31, the plate member 34 becomes
Swinging clockwise in FIG. 2 by the pressure of drainage B1,
It is located on the other inlet side connection port 29 side. Accordingly, the drainage B1 and the solid matter S are guided by the plate member 34 in the drainage basins 23 and 23a, change the flow direction in the direction of the outlet 33, and flow out from the outlet 33 to the drain main pipe 22 on the downstream side.
As a result, the drainage B1 and a part of the solid matter S hardly flow back to the other inlet 32. Conversely, when the drainage B2 (which may include solids S) flows through the drainage main pipe 22a on the upstream side and flows into the drainage tubs 23, 23a from the other inlet 32, the plate Member 34
Swings in the counterclockwise direction in FIG. 2 by the pressure of the drainage B2, and is located on one inlet side connection port 28 side. Therefore, the drainage B2 is supplied to the plate members 34 in the drainage basins 23 and 23a.
, And flows straight out from the outlet 33 to the drain main pipe 22 on the downstream side. As a result, part of drainage B2
There is almost no backflow to one inlet 31. In a state where the plate member 34 is located on the inlet side connection port 28 or 29 side, if there is a slight gap between the plate member 34 and the box body 27, a small amount of drainage B1, B2 is supplied to the inlets 31, 32. Even if the solids S flow backward, the solids S in the drainage water B1 and B2 do not flow backward without passing through the gap, so that there is no danger of the solids S staying. Drainage B flowing into drainage basins 23, 23a
If the flow velocity of B1 and B2 is high, the possibility of backflow to the inlet 32 or 31 increases, but the pressure of the drainage B1 and B2 also increases. Therefore, the plate member 34 is connected to the box bodies 27, 27.
Since it is strongly pressed against the box body so as to eliminate the gap between the drainage B and the solid matter S, the backflow phenomenon of the drainage B1, B2 and the solid matter S can be more reliably prevented. Drain main pipe 22 on the downstream side
The drainage water B1, B2 that has flowed out into the public sewer flows from the drainage outflow pipe to the public sewer main line through a public basin.

In the present embodiment, since there is no step formed at the bottom of the drainage basins 23 and 23a as in the drainage basin shown in FIG. There is no need to form a step on 11 as well. Therefore, since the excavation depth does not become so large at the time of construction, the excavation amount can be reduced as compared with the conventional technique shown in FIG. 7, and the excavation work is easy. In addition, the drain pipe 24 can be installed at an appropriate gradient θ. Many confluence points 21
Even in a certain drainage pipe 24, since the excavation depth does not become extremely deep, it is not necessary to separately provide a facility such as a pump for pumping drainage to a public sewer main pipe. In addition, since the backflow phenomenon of the drainage water B1, B2 and the solid matter S can be prevented, it is possible to prevent the drainage pipe 24 from being clogged due to the stagnation of the solid matter S.

FIG. 5 is a plan view showing various application examples of the drainage basin of the present invention. The same or corresponding parts as those of the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted. Only different parts will be described. Each of the drainage basins 50a to 50e shown in FIGS.
1, a basin arranged at the junction 21 of B2.
1a to 51e, and a plurality of inlet side connection ports 28, 29
And an outlet side connection port 30 and a plate member 34.
In the drainage boxes 50a to 50e, two or three inlet-side connection ports 28 and 29 are attached to the box bodies 51a to 51e at an angle of 180 degrees or less from each other. Further, the outlet-side connection port 30 is separated from the central axis of the inlet-side connection port by an angle of 90 to 180 degrees,
It is attached to the box bodies 51a to 51e. The plate member 34 can swing freely around the junction F located on the upstream side inside the box body as the swing center. The junction F is
The box bodies 51a to 51 substantially facing the outlet side connection port 30
1e, and is located between one entrance-side connection port and another entrance-side connection port.

In the drainage cell 50a of the "parallel / 90 degree merging" type shown in FIG.
It has a 45-degree elbow 52 that can be rotated substantially 180 degrees. By rotating the elbow 52 by 45 degrees, the inflow direction of the drainage B1 flowing through the inlet-side connection port 28 is changed to the drainage main pipe 22.
a, 22 can be switched in parallel or at right angles. In the drainage basin 50b of the "left and right merging" type shown in FIG. 5B, the inflow directions of the drainage water B1 and B2 are opposite by 180 degrees, and the outlet side connection port 30 is oriented at right angles to the inflow direction. . The drainage basin 50c of the “three-way merging” type shown in FIG.
a, 22 with respect to the drainage inflow pipe 20 in a direction substantially 90 degrees.
And another drainage inflow pipe 20 having a direction of approximately 45 degrees is connected to each other. 5D shows a case where the drainage inflow pipe 20 is inclined by approximately 45 degrees with respect to the drainage main pipes 22a and 22. Drainage basin 50 of the “parallel confluence” type shown in FIG.
e shows a case where the drainage inflow pipe 20 is parallel to the drainage main pipes 22a and 22. The drainage basins 50a to 50e shown in FIG. In the drawings, the same reference numerals indicate the same or corresponding parts.

[0020]

As described above, the present invention is constructed as described above, so that the depth of excavation when embedding the drainage pipe in the ground is not so large, and the drainage pipe due to stagnation of solids in the drainage is not formed. Clogging can be prevented.

[Brief description of the drawings]

FIGS. 1 to 5 are views showing an example of an embodiment of the present invention, and FIG. 1 is a front sectional view showing a state where a drainage basin of the present invention is installed.

FIG. 2 is a plan view of FIG.

FIG. 3 is a partially enlarged perspective view of the drainage basin.

FIG. 4 is a partially enlarged perspective view of another drainage basin showing a modification of the mounting structure of the plate member.

FIG. 5 is a plan view showing various application examples of the drainage basin of the present invention.

6 (A) is a front sectional view showing a state where a conventional drainage basin is installed, and FIG. 6 (B) is a plan view of FIG. 6 (A).

7 (A) is a front sectional view showing a state in which another conventional drainage basin is installed, and FIG. 7 (B) is a plan view of FIG. 7 (A).

[Explanation of symbols]

 Reference Signs List 20 drainage inflow pipe (inflow side pipe) 21 junction 22 downstream drainage main pipe (outflow side pipe) 22a upstream side drainage main pipe (inflow side pipe) 23,23a drainage basin 24 drainage pipeline 26 cleaning port 27,27a basin Main body 28, 29 Inlet side connection port 30 Outlet side connection port 31, 32 Inlet 34 Plate member 37 Bottom inner surface 38 Inner surface of cell body 40, 40a Cylindrical concave part 41 Engagement part 50a to 50e Drainage cell B1, B2 Drainage C1 Central axis of inlet side connection port C4 Central axis of cylindrical recess E Horizontal reference plane F Merging point S Solid matter θ Gradient

Claims (6)

[Claims] 1. A drainage basin disposed at a junction of a plurality of drainage in a drainage pipe buried underground, wherein a basin body having a cleaning port mounted on an upper part thereof, and a plurality of inflow side pipes are provided. A plurality of inlet-side connection ports provided in the main body for connection, an outlet-side connection port provided in the main body for connecting an outflow pipe, and drainage flowing from the inlet-side connection port. A drainage basin comprising: a plate member swingably mounted inside the tub body for guiding and changing the flow direction to the direction of the outlet-side connection port. 2. The drainage basin according to claim 1, wherein the plate member swings freely around a merging point located on an upstream side inside the basin body as a swing center. 3. The two or three inlet-side connection ports are attached to the box body at an angle of 180 ° or less from each other, and the outlet-side connection port is 90 ° with respect to a central axis of the inlet-side connection port. Attached to the box main body at an angle of 180 degrees or 180 degrees, and the merging point serving as the swing center of the plate member is at a predetermined position of the box main body substantially opposed to the outlet side connection port, and The drainage basin according to claim 2, wherein the drainage basin is located between the entrance-side connection port and another of the entrance-side connection ports. 4. The plate member is oscillated by the flow of the drainage from one of the inlet-side connection ports, and is located on the other of the inlet-side connection ports, and at least the solid matter in the drainage is on the other side. Preventing the backflow to the inflow port on the inlet side connection port side, the plate member is oscillated by the drainage flowing from the other inlet side connection port and located on the one inlet side connection port side. 4. The drainage basin according to claim 1, wherein at least solid matter in the wastewater is prevented from flowing back to the inflow port on the one inlet side connection port side. 5. 5. A predetermined gradient of the inlet-side connection port, the inner surface of the bottom of the box body, and the outlet-side connection port with respect to a horizontal reference plane so that the downstream side gradually decreases in the order of the drainage flow. The drainage basin according to any one of claims 1 to 4, wherein the drainage basin is formed so as to have. 6. A cylindrical recess having a central axis in a direction perpendicular to the horizontal reference plane is provided on an inner surface of the box body, and is formed at an edge of the plate member arranged in the vertical direction. The drainage basin according to claim 5, wherein the cylindrical engaging portion is fitted into the cylindrical concave portion so that the plate member swings freely in the horizontal direction.