Backflow prevention device and drainage manhole equipped therewith

Abstract

To provide a backflow prevention device which has a simple structure and high reliability, can have a water sealing function, is easy to maintain, hardly causes clogging of drainage by foreign matter, and does not require a dedicated installation space, and to provide a catch basin equipped with the device.MEANS FOR SOLVING THE PROBLEM: There is provided a backflow prevention device consisting of a T-shaped cylindrical body with an outlet opening horizontally, an inlet opening vertically downward, and an inspection port opening vertically upward. The inspection port has a lid removably attached thereto, and the inlet is provided with backflow prevention means that allows the flow of wastewater through the inlet from the bottom upwards and prevents the flow of wastewater through the inlet from the top downwards. There is also provided a catch basin equipped with the device.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a backflow prevention device and a drainage tub equipped with the device. In particular, in a T-shaped cylindrical body having an outlet, an inlet, and an inspection port with a lid, a backflow prevention means is attached to the downward-opening inlet that allows the flow of drainage passing upward through the inlet and blocks the flow of drainage attempting to pass downward through the inlet. The present invention relates to a backflow prevention device and a drainage tub equipped with the same.

Background Art

[0002] Generally, the drainage discharged from drainage facilities such as toilets, bathrooms, and kitchens in houses, etc. is collected in a drainage tub installed on the premises via drain pipes connected to each drainage facility, and the drainage collected in the drainage tub flows out to the main sewer pipe via a public tub or a manhole. Also, the rainwater that has fallen on the roof of a building, etc. may be collected in a rainwater tub on the premises and then merged into the above drainage path.

[0003] And since foreign substances and the like are mixed in the above-described drainage (including rainwater) and foul odors are also generated, generally, a drainage trap as described in, for example, Japanese Patent Application Laid-Open No. 2006-112154 (Patent Document 1) is provided in the middle of the drainage path, or a drainage tub equipped with a dedicated drainage trap as described in Japanese Patent Application Laid-Open No. 11-2,472,81 (Patent Document 2) is provided to prevent foul odors and backflow water generated in downstream drainage facilities such as the main sewer pipe from entering the house.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, drain traps like the one described in Patent Document 1 must be installed separately from the drain manhole in the middle of the drainage route, which not only requires a dedicated installation space but also complicates the drainage route, increasing construction time and costs. Furthermore, because the drain trap described in Patent Document 1 uses a spherical float as a check valve, foreign matter tends to accumulate between the float and the wall of the space in which the float moves up and down, which can lead to the float (check valve) failing to function.

[0006] On the other hand, the drain manhole described in Patent Document 2 has a built-in drain trap, so it does not require a dedicated installation space like the drain trap described in Patent Document 1. However, since the drain trap described in Patent Document 2 is a downward-facing U-shaped drain trap, there is a problem that foreign matter will settle and accumulate inside the trap unless it is frequently cleaned, causing it to quickly become clogged.

[0007] Therefore, the present invention aims to provide a backflow suppression device that has a simple structure, is highly reliable, and has a water-sealing function, is easy to maintain, is less prone to clogging by foreign matter in the wastewater, and does not require a dedicated installation space like the drain trap described in Patent Document 1, as well as a drain manhole equipped with the device. [Means for solving the problem]

[0008] The inventors of the present invention have diligently studied the configuration of a backflow prevention device that can be easily installed in rainwater catch basins, drainage catch basins, etc., and the manner in which it can be installed in drainage catch basins. As a result, they have found that the above problem can be solved by installing a check valve horizontally in the downward-opening inlet of a T-shaped cylindrical body equipped with an outlet, an inlet, and an inspection port with a lid, which allows the flow of drainage to pass upward through the inlet and prevents the flow of drainage to pass downward through the inlet, and have completed the present invention.

[0009] In other words, the present invention provides a backflow suppression device in which a T-shaped cylindrical body has an outlet opening horizontally, an inlet opening vertically downward, and an inspection port opening vertically upward, the inspection port is detachably fitted with a cover, and the inlet is fitted with a backflow suppression means that allows the flow of wastewater passing through the inlet from bottom to top and prevents the flow of wastewater passing through the inlet from top to bottom.

[0010] Furthermore, in the present invention, the backflow suppression means preferably comprises a valve body and an annular mounting portion that rotatably supports the valve body, and is configured such that when the valve body is positioned horizontally, it closes the opening of the mounting portion, and when it rotates upward above the horizontal direction, it opens the opening of the mounting portion.

[0011] In the backflow prevention device of the present invention, a check valve (valve body) is horizontally positioned in a T-shaped cylindrical inlet that opens downwards, and the valve body is configured to rotate between a horizontal position and an inclined position above it. Therefore, for wastewater passing upward through the inlet, the valve body is pressed to tilt upwards, resulting in an "open" state that allows the flow. On the other hand, for wastewater attempting to pass downward through the inlet, the valve body is pressed to position itself horizontally, resulting in a "closed" state that reliably prevents the flow.

[0012] In the backflow suppression device of the present invention, in order to enhance the backflow suppression function while also ensuring the smooth flow of forward-flowing wastewater, the valve body is equipped with a buoyancy generating section (hollow section) that is smaller than the specific gravity of water, and is configured to open smoothly due to the buoyancy generated by the forward-flowing wastewater rising from bottom to top. When backflow water is generated, the backflow water collides with and accumulates on the upper surface on the downstream side of the valve body, but there is basically no wastewater on the lower surface on the upstream side of the valve body, so the valve body does not malfunction in the direction of opening due to the buoyancy generating section.

[0013] In this invention, the valve body may be directly attached to the inlet of the cylindrical body without using a mounting part. However, as described above, by configuring the backflow suppression means with a valve body and a mounting part, and attaching it to the inlet of the cylindrical body via the mounting part, the valve body can be easily attached and detached, improving the maintainability of the backflow suppression means. Furthermore, the mounting part may be configured to be attachable and detachable from inside the cylindrical body. In this case, the backflow suppression means can be easily maintained by removing the cover of the backflow suppression device.

[0014] The backflow suppression device of the present invention can also easily and effectively perform a water seal function by attaching the outlet of the device to the outlet of a drainage manhole having a storage section at the bottom, and positioning the inlet of the device so as to be immersed in the wastewater accumulated in the storage section. In this case, since there is no part inside the backflow suppression device that induces the settling and accumulation of foreign matter, such as a downward-facing U-shaped drain trap, clogging by foreign matter is prevented, and the effort and frequency of cleaning the inside of the backflow suppression device are also greatly reduced.

[0015] Furthermore, as described above, in a drainage manhole equipped with the backflow suppression device of the present invention, foreign matter that flows into the manhole along with the wastewater will not flow to the inlet of the device due to its specific gravity, but will instead flow into the storage section of the manhole and settle. Since the storage section has a larger space than the backflow suppression device, maintenance such as cleaning is easy, and if a removable bucket or the like is prepared in advance in the storage section, foreign matter accumulated in the storage section can be removed very easily.

[0016] According to the present invention, the backflow suppression device has a main body made of a T-shaped cylindrical body, and the check valve is not of the float type but a simple cantilevered on / off valve, resulting in an extremely simple structure, excellent durability, and high reliability with virtually no malfunctions or failures. Furthermore, a detachable lid is provided at the upper opening (inspection port) of the T-shaped cylindrical body, which not only facilitates maintenance of the backflow suppression device but also simplifies (unifies) the flow of wastewater inside the cylindrical body between the downward-opening inlet and the sideways-opening outlet. Combined with the effects of the structural simplification described above, this effectively prevents clogging inside the backflow suppression device.

[0017] In this specification, the term "drainage manhole" is used to include not only drainage manholes used in sewage pathways, but also rainwater manholes used in rainwater pathways, which may contain foreign matter such as mud and fallen leaves.

[0018] In the present invention, the mounting portion of the backflow suppression means has a first connecting portion having a socket shape and a second connecting portion having a socket shape and positioned outside all or part of the outer circumference of the first connecting portion, and the central axis of the first connecting portion and the central axis of the second connecting portion may be arranged to be parallel and eccentric to each other.

[0019] In the present invention, by configuring the mounting portion of the backflow suppression means as described above, the first connection portion having a receiving opening shape is kept at a constant diameter to match the outer shape (diameter, etc.) of the valve body, while the second connection portion having an outer insertion opening shape can be connected (extrapolated) to any diameter of the inlet of the T-shaped cylindrical body, either directly or via a diameter adjustment adapter. Furthermore, having the first connection portion on the mounting portion is convenient as it serves as a handle when attaching the backflow suppression means to the inlet of the cylindrical body.

[0020] Furthermore, when a short pipe extending downward is connected to the first connection portion of the attachment portion attached to the inlet of the cylindrical body, when drainage enters the short pipe, the air in the short pipe is compressed and the pressure increases due to the rise of the liquid level, so that the valve body can be more easily opened. Also, by connecting a member having a trap function to the first connection portion, an anti-odor function can be exhibited by forming a water seal.

[0021] In addition, since the second connection portion is a socket disposed outside the valve body, pipes can be connected (externally inserted) from both end sides. For example, by connecting (externally inserting) a first pipe to one end of the second connection portion and connecting (externally inserting) a second pipe to the other end, the backflow prevention device of the present invention can also be used as a pipe joint.

[0022] As the drain box to which the backflow prevention device of the present invention is applied, it preferably includes a cylindrical rising portion with openings at the upper and lower portions, and a bottomed and cylindrical storage portion provided at the lower portion of the rising portion and communicating with the rising portion, and upstream and downstream drain pipe connection ports are formed on the side wall of the rising portion. By connecting the inlet of the backflow prevention device of the present invention to the downstream drain pipe connection port, it can be used as a drain box having a backflow prevention function and a water seal function.

[0023] In the present invention, the directions of the upstream drain pipe connection port and the downstream drain pipe connection port provided on the side wall of the rising portion are preferably such that their central axes are separated by 90° or more and 270° or less in a plan view. In order to promote a smooth drainage flow, it is more preferable that the upstream drain pipe connection port and the downstream drain pipe connection port are arranged at positions facing each other. Also, if the central axis is within the above-mentioned attachment range (angle), a plurality of upstream drain pipe connection ports may be provided.

[0024] In addition, the drain box provided with the backflow prevention device of the present invention may be configured with the rising portion and the storage portion as separate parts independent of each other in consideration of ease of molding and construction. Also, in consideration of cost reduction and ease of processing, the rising portion and the storage portion may be the same part integrally formed with each other.

Advantages of the Invention

[0025] According to the present invention, in a T-shaped cylindrical body having an outlet opening horizontally, an inlet opening vertically downward, and an inspection opening opening vertically upward, a lid portion is detachably attached to the inspection opening, and a backflow prevention means for allowing a drainage flow passing through the inlet from bottom to top and blocking a drainage flow passing through the inlet from top to bottom is attached to the inlet, and a backflow prevention device is provided.

[0026] In the backflow prevention device of the present invention, a check valve (valve body) is horizontally arranged at the inlet opening downward of the T-shaped cylindrical body, and the valve body is configured to be rotatable between a horizontal position and an inclined position above it. Therefore, for the drainage passing through the inlet upward, the valve body is pressed to tilt upward to be in an "open" state, while for the drainage attempting to pass through the inlet downward, the valve body is pressed to be horizontally arranged to be in a "closed" state, and thus backflow can be reliably blocked.

[0027] The backflow prevention device of the present invention can also easily and effectively exhibit a water sealing function by attaching the outlet of the device to the outlet of a drain pan having a storage portion and arranging the inlet of the device to be immersed in the drainage retained in the storage portion. In this case, since there is no portion in the backflow prevention device that attracts sedimentation and accumulation of foreign substances like a downward U-shaped drainage trap, clogging by foreign substances is prevented, and the frequency of cleaning inside the backflow prevention device is also significantly reduced.

[0028] The backflow prevention device of the present invention is mainly composed of a T-shaped cylindrical body and a simple cantilever-supported on-off valve, so it has an extremely simple structure, excellent durability, and high reliability with almost no failures or malfunctions. In addition, since a lid portion is detachably arranged at the upper opening (inspection opening) of the T-shaped cylindrical body, not only is maintenance facilitated, but clogging inside the device can be strongly prevented by simplifying and concentrating the drainage flow.

Brief Description of the Drawings

[0029] [Figure 1] This is a perspective view of the drain manhole of the present invention, showing an installation method of the backflow suppression device of the present invention by making a part of the main body transparent. [Figure 2] Figure 1 is a perspective view of the backflow suppression device, in which a portion of the main body is transparent. [Figure 3] Figure 2 is a cross-sectional view of the backflow suppression device shown, taken at cross-section AA. [Figure 4] Figure 2 is a perspective view of the backflow suppression means of the backflow suppression device shown. [Figure 5] Figure 4 is a cross-sectional view of the backflow suppression means shown, taken at the BB cross-section. [Modes for carrying out the invention]

[0030] Hereinafter, a backflow suppression device 1 and a drainage manhole 6 equipped therewith according to one embodiment of the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the embodiments shown below, and various modifications are possible without departing from the technical spirit of the present invention.

[0031] <Backflow suppression device> Figure 1 shows a perspective view of a drain manhole 6 according to one embodiment of the present invention, illustrating how the backflow suppression device 1 according to one embodiment of the present invention is installed by making a part of the main body transparent. As shown in Figure 1, the backflow suppression device 1 of this embodiment is attached to the downstream drain pipe connection port 71 in a drain manhole 6 with a bottom (bottom 80) that has an upstream drain pipe connection port 70 and a downstream drain pipe connection port 71, for example.

[0032] Figure 2 shows a perspective view of the backflow suppression device 1 shown in Figure 1, with a part of the main body made transparent, and Figure 3 shows a cross-sectional view of the backflow suppression device 1 shown in Figure 2, cut along the AA cross section. As shown in Figures 2 and 3, the backflow suppression device 1 of this embodiment consists of a T-shaped cylindrical body 2, a lid 3, and a backflow suppression means 4. The T-shaped cylindrical body 2 has an outlet 20 that opens horizontally, an inlet 21 that opens vertically downward, and an inspection port 22 that opens vertically upward. The lid 3 described above is detachably attached to the inspection port 22, and the backflow suppression device 1, which will be described later, is attached to the inlet 21. There are no particular limitations on the material used for the backflow suppression device 1, which consists of the cylindrical body 2, the lid 3, and the backflow suppression means 4, but it is preferable to use a plastic material such as polyvinyl chloride resin from the standpoint of durability, moldability, processability, and cost.

[0033] Here, in the backflow suppression device 1 of this embodiment, "opening horizontally" means that the central axis (not shown) of the outlet 20 extends substantially horizontally, and the end face of the outlet 20 is formed on a plane perpendicular to the central axis. Furthermore, "opening downward in the vertical direction" means that the central axis (not shown) of the inlet 21 extends substantially vertically, and the end face of the inlet 21 is formed downward on a plane perpendicular to the central axis, and "opening upward in the vertical direction" means that the central axis (not shown) of the inspection port 22 extends substantially vertically, and the end face of the inspection port 22 is formed upward on a plane perpendicular to the central axis.

[0034] In this embodiment, of the three openings 20, 21, and 22 of the T-shaped cylindrical body 2 that constitutes the main body of the backflow prevention device 1, the inspection port 22 is normally fitted with a lid 3 and sealed. Therefore, the flow path inside the cylindrical body 2 is simplified (unified) between the inlet 21, which opens downward like a 90° elbow, and the outlet 20, which opens sideways. As a result, the flow of wastewater inside the cylindrical body 2 is also concentrated in the above flow path, and combined with the effect of structural simplification, clogging inside the backflow prevention device 1 is strongly prevented. Furthermore, unlike a 90° elbow, the cylindrical body 2 has an inspection port 22, so the downstream drain pipe can be easily inspected without removing the backflow prevention device 1 from the downstream drain pipe connection port 71 of the drain manhole 6.

[0035] Furthermore, unlike a 90° elbow, the backflow suppression device 1 of this embodiment has an inspection port 22, so by removing the cover 3, the backflow suppression means 4 can be easily accessed and maintenance can be easily performed. In particular, when the valve body 40 of the backflow suppression means 4 rotates toward the inside of the backflow suppression device 1, as in this embodiment, it becomes difficult to remove foreign matter accumulated on the upper surface (downstream side) of the valve body 40 with a structure like a 90° elbow, so it is extremely important to provide an inspection port 22 on the upper part of the valve body 40.

[0036] The mechanism for attaching and detaching the lid 3 is not particularly limited, and any known attachment and detachment mechanism can be used. However, from the viewpoint of making it easy to attach and detach the lid 3, and yet reliably preventing it from falling off due to drainage pressure, etc., when it is attached to the inspection port 22, it is preferable to use a screw fastening mechanism such as cutting male and female threads on the lid 3 and the inspection port 22, or a bayonet mechanism.

[0037] Figure 4 shows a perspective view of the backflow suppression means 4 of the backflow suppression device 1 shown in Figure 2, and Figure 5 shows a cross-sectional view of the backflow suppression means 4 shown in Figure 4, cut along the BB cross section. As shown in Figures 4 and 5, the backflow suppression means 4 of this embodiment comprises a valve body 40 and an annular mounting portion 41 that cantileverably support the valve body 40, and is attached to the inlet 21 of the backflow suppression device 1 such that the valve body 40 is positioned horizontally, or in other words, the valve seat portion (opening) 410 of the mounting portion 41 that contacts the valve body 40 is positioned horizontally.

[0038] In this embodiment, the valve body 40 may be directly attached to the inlet 21 of the cylindrical body 2 without using the mounting portion 41 (not shown). However, as described above, by configuring the backflow suppression means 4 with the valve body 40 and the mounting portion 41, and attaching it to the inlet 21 of the cylindrical body 2 using the mounting portion 41, the mounting accuracy of the valve body 40 is improved, and attachment and detachment from the cylindrical body 2 are made easier, improving the maintainability of the backflow suppression means 4. In addition, although not shown, the mounting portion 41 may be configured to be attachable and detachable from inside the cylindrical body. In this case, the backflow suppression means 4 can be easily maintained by removing the lid portion 3 of the backflow suppression device 1.

[0039] In this embodiment, the valve body 40 operates to close the opening (valve seat portion) 410 of the mounting portion 41 when positioned horizontally, and to open the opening (valve seat portion) 410 of the mounting portion 41 when rotated upward from the horizontal direction.

[0040] In other words, in the backflow suppression device 1 of this embodiment, the valve body 40 is positioned horizontally on the downward-opening inlet 21 of the cylindrical body 2, and the valve body 40 is mounted so as to be rotatable between the horizontal position and an inclined position above it. Therefore, for forward-flowing drainage passing through the inlet 21 from bottom to top, the valve body 40 is pressed to tilt upward, resulting in an "open" state, which allows the flow. On the other hand, for reverse-flowing drainage attempting to pass through the inlet 21 from top to bottom, the valve body 40 is pressed to be positioned horizontally, resulting in a "closed" state, which can reliably block the flow.

[0041] Thus, in the backflow suppression device 1 of this embodiment, the main body is made of a T-shaped cylindrical body 2, and the check valve is not of the float type but uses a simple cantilevered on / off valve body 40. As a result, it has an extremely simple structure, and a highly reliable device with excellent durability and virtually no malfunctions or failures can be obtained.

[0042] In this embodiment, in order to enhance the backflow suppression function, the valve body 40 is shaped so that its upper surface (downstream surface) is recessed downward (upstream side) to receive a large pressing force in the closing direction due to backflow water (Figures 3 and 5). Alternatively, if the smooth flow of forward-flow drainage during normal operation is to be prioritized, the valve body 40 may be shaped so that its lower surface (upstream surface) is recessed upward (downstream side) to receive a large pressing force in the opening direction due to forward-flow drainage.

[0043] In this embodiment, in order to enhance the backflow suppression function while also ensuring the smooth flow of forward-flowing wastewater, the valve body 40 is equipped with a buoyancy generating section (hollow section) 400 that is less specific than the specific gravity of water, and is configured to open smoothly due to the buoyancy generated by the forward-flowing wastewater rising from bottom to top. In addition to forming a hollow section inside the valve body 40 as described above, the buoyancy generating section 400 may also be formed by forming the valve body itself from a resin material less specific than the specific gravity of water, or by attaching a buoyancy generating section made of a resin material less specific than the specific gravity of water to the valve body 40.

[0044] Furthermore, when backflow occurs, the backflow collide with and accumulates on the recessed upper surface of the downstream side of the valve body 40, but there is basically no drainage on the lower surface of the upstream side of the valve body 40, so the buoyancy generating unit 400 does not malfunction to open the valve body 40.

[0045] As shown in Figure 5, in this embodiment, the mounting portion 41 of the backflow suppression means 4 includes a first connecting portion 411 having a socket shape and a second connecting portion 412 having a socket shape and being located outside all or part of the outer circumference of the first connecting portion 411, with the central axis a of the first connecting portion 411 and the central axis b of the second connecting portion 412 being arranged to be parallel and eccentric to each other. That is, the first connecting portion 411 and the second connecting portion 412 form a double-pipe structure that is separated from each other near the pivot axis of the valve body 40, but form a single-pipe structure that is integrated with each other in the opposing region rotated 180° from the pivot axis.

[0046] Furthermore, although not shown in the diagram, the second connection part may be located on the outer edge of the entire circumference of the first connection part, and the central axis of the first connection part and the central axis of the second connection part may be located coaxially with each other. In this case, the first connection part and the second connection part form a double-tube structure that is separated from each other around the entire circumference.

[0047] As described above, the mounting portion 41 of the backflow suppression means 4 has a first connecting portion 411 and a second connecting portion 412. The first connecting portion 411, which has a receiving opening shape, is set to a constant diameter to match the outer shape (diameter, etc.) of the valve body 40, while the second connecting portion 412, which has a socket opening shape, can be attached directly or via a diameter adjustment adapter to the inlet 21 of the T-shaped cylindrical body 2. Therefore, the second connecting portion 412 can be easily connected (inserted) to an inlet 21 of any diameter. In addition, the presence of the first connecting portion 411 on the mounting portion 41 is convenient as it serves as a handle when attaching the backflow suppression means 4 to the inlet 21 of the cylindrical body 2.

[0048] Furthermore, by connecting a downward-extending short pipe (not shown) to the first connection part 411 of the mounting part 41 attached to the inlet 21 of the cylindrical body 2, when wastewater enters the short pipe, the air inside the short pipe is compressed due to the rise in the liquid level, increasing the pressure and making it easier to open the valve body. In addition, by connecting a member with a trap function (not shown) to the first connection part 411, an odor-preventing function can be achieved by forming a water seal.

[0049] Furthermore, since the second connection part 412 is a socket located on the outside of the valve body 40, it is possible to connect (extrapolate) piping from both ends. For example, by connecting (extrapolating) the first piping to one end of the second connection part 412 and the second piping to the other end, the backflow suppression device 1 can be used as a pipe joint.

[0050] <Drainage manhole equipped with backflow prevention device> The backflow prevention device 1 of this embodiment can perform a water-sealing function by attaching the outlet 20 of the device 1 to the outlet (downstream drain pipe connection port 71) of a typical drain manhole 6. Specifically, the drain manhole 6 of this embodiment, which is capable of performing a water-sealing function, is shown in Figure 1 and comprises a cylindrical riser portion 7 with an open top and bottom, and a bottomed (bottom portion 80) and cylindrical storage portion 8 that communicates with the riser portion 7 and is provided at the bottom of the riser portion 7. The side wall of the riser portion 7 has an upstream drain pipe connection port 70 and a downstream drain pipe connection port 71 formed therein. There are no particular limitations on the material used for the riser portion 7, the storage portion 8, or the drain manhole 6 in which they are integrally molded, and they may be made of plastic material such as polyvinyl chloride resin, concrete material, or a combination thereof.

[0051] By connecting the outlet 20 of the aforementioned backflow prevention device 1 to the outlet (downstream drain pipe connection port 71) and positioning the inlet 21 of the device 1 so as to be immersed in the wastewater accumulated in the storage section 8 of the drain basin 6, the drain basin 6 of this embodiment can be configured to exhibit both backflow prevention and water sealing functions.

[0052] Thus, in the drain pit 6 of this embodiment, the storage section 8 only needs to have a space capable of accumulating wastewater below the bottom of the upstream drain pipe connection port 70 and the bottom of the downstream drain pipe connection port 71. For this reason, the inlet 21 of the backflow prevention device 1, which is positioned to be immersed in the wastewater accumulated in the storage section 8, has its end face positioned below the bottom of the upstream drain pipe connection port 70 and the bottom of the downstream drain pipe connection port 71. Also, since wastewater normally flows from the upstream drain pipe connection port 70 through the drain pit 6 to the downstream drain pipe connection port 71, the bottom of the downstream drain pipe connection port 71 is positioned at the same level as or lower than the bottom of the upstream drain pipe connection port 70.

[0053] In the drain manhole 6 of this embodiment, even if the inlet 21 of the backflow prevention device 1 is no longer submerged in the wastewater due to the decrease in the wastewater accumulated in the storage section 8, the backflow prevention function is maintained. Furthermore, the valve body 40 is positioned horizontally and closed due to its own weight, so the odor-preventing function by creating a pseudo-water seal also works, effectively preventing foreign matter and foul odors from flowing from the downstream drain pipe to the upstream drain pipe.

[0054] On the other hand, if the amount of wastewater accumulated in the storage section 8 increases, in the drain manhole 6 of this embodiment, the end face of the inlet 21 of the backflow prevention device 1 is located at least below the bottom of the downstream drain pipe connection port 71, so it will be immersed in the wastewater again, and the drain manhole 6 will perform its original backflow prevention and water sealing functions.

[0055] Thus, in this embodiment, the drain manhole 6 does not have a part that attracts the settling and accumulation of foreign matter, such as a downward-facing U-shaped drain trap, within the backflow prevention device 1. Therefore, clogging by foreign matter is prevented, and the effort and frequency required to clean the inside of the backflow prevention device 1 are also greatly reduced.

[0056] Furthermore, in the drain pit 6 of this embodiment, foreign matter and other objects that flow into the drain pit 6 along with the wastewater will not flow into the inlet 21 of the backflow suppression device 1 due to their specific gravity, but will instead flow into the storage section 8 of the drain pit 6, which is located in front of the inlet 21, and settle there. Since the storage section 8 has a larger space than the backflow suppression device 1, maintenance such as cleaning is easy, and if a removable bucket or the like is prepared in advance inside the storage section 8, foreign matter accumulated inside the storage section 8 can be easily removed.

[0057] In this embodiment, the orientation of the upstream drain pipe connection port 70 and the downstream drain pipe connection port 71 provided on the side wall of the riser portion 7 is preferably such that their respective central axes are separated by 90° to 270° in a plan view. To promote a smooth drainage flow, it is even more preferable that the upstream drain pipe connection port 70 and the downstream drain pipe connection port 71 are positioned opposite each other, as shown in Figure 2. Furthermore, multiple upstream drain pipe connection ports 71 may be provided as long as their central axes are within the above-mentioned mounting range (angle).

[0058] Furthermore, the drainage manhole 6 equipped with the backflow suppression device 1 of this embodiment may be constructed with the riser section 7 and the storage section 8 from separate, independent parts, taking into consideration ease of molding and construction. Alternatively, the riser section 7 and the storage section 8 may be made from the same part, integrally molded together, taking into consideration cost reduction and ease of processing. [Explanation of symbols]

[0059] 1. Backflow prevention device 2. T-shaped cylindrical body 20... Outlet 21...Inlet 22...Inspection hatch 3...Lid part 4. Measures to prevent backflow 40... Valve body 400...Buoyancy generating section 41..Mounting part 410... Valve seat (opening) 411...First connection section 412...Second connection point 6. Drainage manhole 7...Rising section 70... Upstream drain pipe connection port 71... Downstream drain pipe connection port 8. Storage section 80...Bottom a·····Central axis of the first connection point b....The central axis of the second connection point

Claims

1. An outlet that opens horizontally, An inlet that opens vertically downwards, In a T-shaped cylindrical body equipped with an inspection port opening vertically upward, A lid is detachably attached to the inspection opening, and A backflow suppression device is provided, wherein the inlet is fitted with a backflow suppression means that allows the flow of wastewater from bottom to top through the inlet and prevents the flow of wastewater from top to bottom through the inlet.

2. The backflow suppression means comprises a valve body and an annular mounting portion that rotatably supports the valve body, and The backflow suppression device according to claim 1, characterized in that the valve body closes the opening of the mounting portion when positioned horizontally and opens the opening of the mounting portion when rotated upward from the horizontal direction.

3. The mounting portion includes a first connecting portion having a socket shape and a second connecting portion having a socket shape, which is located outside all or part of the outer circumference of the first connecting portion. The backflow suppression device according to claim 2, characterized in that the central axis of the first connection part and the central axis of the second connection part are arranged parallel and eccentrically to each other.

4. The backflow suppression device according to claim 2, characterized in that the valve body is provided with a buoyancy generating portion that is less than the specific gravity of water.

5. The backflow suppression device according to claim 4, characterized in that the buoyancy generating portion is configured by forming a hollow portion within the valve body.

6. A cylindrical rising section with openings at the top and bottom, Communicating with the aforementioned rising section, and a bottomed, cylindrical storage section provided at the lower part of the rising section In a drainage manhole equipped with, The side wall of the aforementioned rising section has an upstream drain pipe connection port and a downstream drain pipe connection port formed therein, The drainage manhole is characterized in that the outlet of a backflow suppression device according to any one of claims 1 to 5 is connected to the downstream drainage pipe connection port.

Images