Backflow prevention basin

Abstract

To provide a backflow prevention basin that prevents intrusion of drainage flowing back through a drainage pipeline to an upstream side, while suppressing occurrence of drainage clogging due to filth even when an amount of the drainage is small.SOLUTION: A backflow prevention basin 10 is provided in the drainage pipeline connecting an indoor drainage facility and a sewer pipe. The backflow prevention basin 10 comprises: a catch basin body 11; an inflow pipe part 12 and an outflow pipe part 13 for drainage provided on a side wall of the catch basin body 11; and a backflow prevention valve 14 provided in the catch basin body 11. The backflow prevention valve 14 has a valve body 141 configured to be able to close a downstream opening 12b of the inflow pipe part 12. A downstream side pipe bottom of the inflow pipe part 12 is located below an upstream side pipe bottom of the inflow pipe part 12.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a backflow prevention block that is installed in a drainage pipeline connecting indoor drainage equipment such as a toilet to a sewer pipe, and prevents wastewater flowing backward through the drainage pipeline from entering the upstream side. [Background technology]

[0002] Generally, wastewater discharged from indoor drainage facilities such as toilets is discharged into the sewer main (hereinafter simply called the sewer pipe) via drainage pipes buried underground. In addition, a drainage basin is usually installed upstream of the connection point of the drainage pipe to the sewer pipe in order to remove and inspect filth such as garbage in the drainage pipe.

[0003] However, when a large amount of rainwater flows into a sewer pipe in a short period of time due to a typhoon or other event, the overflowing wastewater exceeds the drainage capacity of the sewer pipe and flows back up the drainage pipe through the drainage manhole, causing the backflowing wastewater to gush out into the building from the indoor drainage equipment connected to the drainage pipe, or causing sealed water to gush out into the building due to air compressed by the wastewater.

[0004] In response to this, in order to prevent wastewater that has backed up from the sewer pipes from passing through the drainage manhole and spewing out of the indoor drainage system, Patent Document 1 discloses a backflow prevention manhole with a backflow prevention valve attached to the inlet opening inside the drainage manhole.

[0005] In the backflow prevention basin described in Patent Document 1, the valve element of the backflow prevention valve is rotatably attached to the inlet opening so as to incline from the upstream side to the downstream side as it moves from the top to the bottom. For this reason, the valve element of the backflow prevention valve usually blocks the inlet opening by its own weight. As a result, when wastewater flows from the indoor drainage system into the drainage basin, the valve element is lifted by the flow of the wastewater and opens the inlet opening. On the other hand, when wastewater flows back from the sewer pipe into the drainage basin, the valve element blocks the inlet opening by its own weight and the flow of the wastewater, so that it is possible to prevent the wastewater from flowing back through the drainage basin into the upstream drainage pipe. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-126888 A Summary of the Invention [Problem to be solved by the invention]

[0007] With the recent spread of water-saving toilets, the amount of water discharged from indoor drainage systems under normal circumstances has been greatly reduced. However, in the case of the backflow prevention basin described in Patent Document 1, the valve body normally blocks the inlet opening of the drainage basin due to its own weight, so when the amount of water discharged decreases, the valve body becomes difficult to open, and waste such as garbage accumulates around the valve body, causing a problem of clogging the flow.

[0008] In view of the above, the present disclosure aims to provide a backflow prevention manhole that prevents wastewater from flowing back up a drainage pipeline from entering the upstream side, thereby preventing drainage blockages caused by sewage, etc., even when the amount of drainage is small. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, a first aspect of the present disclosure is a backflow prevention manhole provided in a drainage pipeline connecting an indoor drainage system and a sewer pipe to prevent wastewater flowing backward through the drainage pipeline from entering the upstream side, the backflow prevention manhole comprising a drainage manhole body, a wastewater inlet pipe section and an outlet pipe section provided on a side wall of the drainage manhole body, and a backflow prevention valve provided within the drainage manhole body and having a valve body configured to be able to close the downstream opening of the inlet pipe section, wherein the downstream pipe bottom of the inlet pipe section is located lower than the upstream pipe bottom of the inlet pipe section.

[0010] According to the first aspect, in the wastewater inlet pipe section provided on the side wall of the drainage manhole body, the downstream pipe bottom is located lower than the upstream pipe bottom. Therefore, the flow rate of the wastewater increases when the wastewater flows from the upstream side to the downstream side of the inlet pipe section, so that the valve body of the check valve that blocks the downstream opening of the inlet pipe section is easily opened by the flow of the wastewater. Therefore, even when the amount of wastewater is small, the backflow prevention manhole can be prevented from becoming clogged with wastewater.

[0011] A second aspect of the present disclosure is a backflow prevention manhole in the first aspect, wherein the bottom of the drainage manhole body is located below the downstream pipe bottom of the inlet pipe section.

[0012] According to the second aspect, it is possible to avoid a situation in which waste material or the like accumulates downstream of the valve body of the check valve inside the drainage manhole body, thereby preventing the valve body from opening, thereby further preventing drainage blockages caused by waste material or the like.

[0013] A third aspect of the present disclosure is a backflow prevention mass in the first or second aspect, wherein the height difference between the downstream pipe bottom and the upstream pipe bottom in the inlet pipe section is 23% or more of the inner diameter of the piping connected to the inlet pipe section from the upstream side.

[0014] According to the third aspect, the flow rate of the wastewater can be sufficiently increased when the wastewater flows from the upstream side to the downstream side of the inlet pipe, which makes it easier for the valve element of the check valve to open due to the flow of the wastewater, thereby further preventing the drainage from being clogged by sewage or the like.

[0015] A fourth aspect of the present disclosure is a backflow prevention mass in any one of the first to third aspects, wherein the inlet pipe section includes at least a valve pipe attached from the inside of the drainage mass body on the downstream side, and a valve seat surface capable of abutting against the valve body is provided on the downstream end face of the valve pipe.

[0016] According to the fourth aspect, the valve pipe that is opened and closed by the valve body is attached from the inside of the drainage manhole body, so that the valve body can be attached integrally with the valve pipe, making it easier to assemble the backflow prevention manhole.

[0017] A fifth aspect of the present disclosure is a backflow prevention mass in any one of the first to fourth aspects, wherein the inflow pipe section includes at least a first horizontal pipe section arranged upstream and having a horizontal or approximately horizontal pipe bottom, and an inclined pipe section arranged downstream of the first horizontal pipe section and having a pipe bottom that is inclined downwardly toward the downstream side.

[0018] According to the fifth aspect, even if the flow gradient of the piping connected from the upstream side to the inlet pipe section of the backflow prevention mass is small, the piping can be easily connected to the first horizontal pipe section of the inlet pipe section.

[0019] A sixth aspect of the present disclosure is a backflow prevention mass of the fifth aspect, wherein the first horizontal pipe section and the inclined pipe section are integrally molded, the inlet pipe section is inserted into the drainage mass body, and a valve seat surface capable of abutting the valve body is provided on the downstream end face of the inlet pipe section.

[0020] According to the sixth aspect, the number of components of the backflow prevention mass can be reduced, making it easier to assemble the backflow prevention mass.

[0021] A seventh aspect of the present disclosure is a backflow prevention manhole in the fifth or sixth aspect, wherein the inlet pipe section is arranged downstream of the inclined pipe section, is connected to the drainage manhole body, and further includes a second horizontal pipe section having a horizontal or approximately horizontal pipe bottom.

[0022] According to the seventh aspect, the second horizontal pipe section of the inflow pipe section can be easily attached to the side wall of the drainage basin body.

[0023] An eighth aspect of the present disclosure is a backflow prevention mass in any one of the fifth to seventh aspects, wherein an extension line of the pipe axis of the first horizontal pipe section passes through the downstream opening of the inlet pipe section without intersecting the inner wall surface of the inclined pipe section.

[0024] According to the eighth aspect, it is possible to avoid a situation in which the wastewater flow rate decreases as the wastewater flows from the upstream side to the downstream side of the inlet pipe section and collides with the pipe tip of the inclined pipe section, thereby making it possible to realize a state in which the valve body of the check valve is easily opened by the flow of the wastewater.

[0025] A ninth aspect of the present disclosure is a backflow prevention mass which is any one of the first to eighth aspects, in which the downstream side of the inlet pipe section is inserted into the inside of the drainage mass body, the valve body vertically blocks the downstream opening of the inlet pipe section when no drainage is occurring, and a valve seat surface is provided on the peripheral portion of the downstream opening of the inlet pipe section so as to be able to abut against the valve body when drainage backflows.

[0026] According to the ninth aspect, the structure of the inflow pipe section is simplified, making it easy to assemble the backflow prevention mass. In addition, it is easy to open and close the valve body when discharging water, and it is possible to prevent air from being forced upstream when a backflow of wastewater occurs, thereby suppressing the occurrence of a seal break in the drainage pipe.

[0027] A tenth aspect of the present disclosure is a backflow prevention mass in the ninth aspect, wherein the valve seat surface is provided in a shape that flares out in the downstream direction from the inner surface to the end face of the inlet pipe portion.

[0028] According to the tenth aspect, when backflow of wastewater occurs, the water blocking effect of the valve body can be reliably obtained even with a weaker force (water pressure). Effect of the Invention

[0029] According to the present disclosure, a backflow prevention manhole that prevents wastewater from flowing backward through a drainage pipeline from entering the upstream side can prevent drainage blockages caused by sewage, etc., even when the amount of wastewater is small. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a diagram showing an example of a drainage pipeline in which a backflow prevention block according to an embodiment is provided. [Diagram 2]FIG. 2 is a vertical cross-sectional view of the backflow prevention mass according to the embodiment. [Diagram 3] 3 is a cross-sectional view showing a schematic diagram of a connection point between the drainage manhole body and the inflow pipe section in the backflow prevention manhole shown in FIG. 2 and its vicinity. [Figure 4] Figure 4 is a cross-sectional view showing the difference in height between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section in a backflow prevention manhole of the embodiment, and the difference in height between the bottom of the drainage manhole body and the downstream pipe bottom of the inflow pipe section. [Diagram 5] FIG. 5 is a vertical cross-sectional view of a backflow prevention mass according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] (Embodiment) Hereinafter, a backflow prevention mass according to an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiment shown below, and various modifications are possible within the scope of the technical concept of the present disclosure.

[0032] <Example of drainage pipe configuration> The backflow prevention manhole 10 of this embodiment is provided in a drainage pipeline 1 that connects an indoor drainage facility 2 such as a toilet to a sewer pipe (not shown), as shown in Fig. 1, and prevents wastewater flowing backward through the drainage pipeline 1 from entering the upstream side. For example, other drainage manholes 3A, 3B, 3C may be provided between the indoor drainage facility 2 and the backflow prevention manhole 10 in the drainage pipeline 1 to remove and inspect filth such as garbage in the drainage pipeline 1. The piping that constitutes the drainage pipeline 1 is, for example, a polyvinyl chloride pipe VU100 with an inner diameter of 107 mm, and the piping may be provided with a flow gradient of, for example, about 1 / 200 toward the downstream.

[0033] <Example of backflow prevention mass configuration> 2 and 3, the backflow prevention tank 10 includes a drainage tank body 11, an inlet pipe section 12 and an outlet pipe section 13 for wastewater provided on the side wall of the drainage tank body 11, and a backflow prevention valve 14 provided within the drainage tank body 11. The backflow prevention tank 10 may be made of a synthetic resin such as polyvinyl chloride.

[0034] An opening 11a is provided at the top of the drainage manhole body 11 for inserting a height adjustment adjuster or a lid (not shown). The opening 11a has a circular shape with a diameter of about 50 to 300 mm, for example. By inserting the adjuster or lid into the opening 11a, the backflow prevention manhole 10 can be exposed to the ground surface, making it possible to inspect and maintain the backflow prevention manhole 10.

[0035] An opening 11b is provided in the side wall of the drainage manhole body 11, and the downstream side of the inflow pipe section 12 is inserted into the inside of the drainage manhole body 11 through this opening 11b, thereby connecting the drainage manhole body 11 and the inflow pipe section 12. That is, in this embodiment, the drainage manhole body 11 and the inflow pipe section 12 are configured as separate bodies, and the inflow pipe section 12 is inserted from the outside of the drainage manhole body 11 toward the inside.

[0036] The inflow pipe section 12 includes a first horizontal pipe section 121 arranged on the upstream side, an inclined pipe section 122 arranged downstream of the horizontal pipe section 121, and a second horizontal pipe section 123 arranged downstream of the inclined pipe section 122. The first horizontal pipe section 121, the inclined pipe section 122, and the second horizontal pipe section 123 may be integrally molded. The pipe bottoms (bottoms of the pipe inner walls) of the first horizontal pipe section 121 and the second horizontal pipe section 123 are horizontal or approximately horizontal. The pipe bottom of the inclined pipe section 122 is inclined downward toward the downstream side. Therefore, the pipe bottoms of the inclined pipe section 122 and the second horizontal pipe section 123 are located lower than the pipe bottom of the first horizontal pipe section 121. In other words, the pipe bottom on the downstream side of the inflow pipe section 12 is located lower than the pipe bottom on the upstream side of the inflow pipe section 12.

[0037] Although not shown, the upstream opening 12a of the inflow pipe section 12 (first horizontal pipe section 121) is connected to a pipe (upstream pipe on the indoor drainage equipment 2 side) constituting the drainage pipe line 1. Specifically, the outer diameter of the upstream pipe is approximately equal to the inner diameter of the first horizontal pipe section 121, and the downstream end of the upstream pipe is inserted into the first horizontal pipe section 121. A step 121a is provided along the inner circumference of the pipe at the boundary between the first horizontal pipe section 121 and the inclined pipe section 122. The inner peripheral surface of the inclined pipe section 122 may have a curved surface that bulges outward when viewed from the pipe axis of the inclined pipe section 122. This curved surface can smooth the flow of drainage. The inner diameters of the inclined pipe section 122 and the second horizontal pipe section 123 may be approximately equal to the inner diameter of the upstream pipe inserted into the first horizontal pipe section 121. The tip of the upstream pipe inserted into the first horizontal pipe section 121 abuts against the step 121a, whereby the upstream pipe is positioned in the insertion direction.

[0038] The outer diameter of the second horizontal pipe section 123 is approximately equal to the diameter of the opening 11b of the drainage manhole body 11, and the second horizontal pipe section 123 is inserted into the drainage manhole body 11 through the opening 11b. That is, the downstream opening 12b of the inflow pipe section 12 (second horizontal pipe section 123) is located closer to the inside of the drainage manhole body 11 than the opening 11b of the drainage manhole body 11. A protrusion 123a is provided along the outer periphery of the pipe at the boundary between the second horizontal pipe section 123 and the inclined pipe section 122. When the second horizontal pipe section 123 is inserted into the drainage manhole body 11, the protrusion 123a of the second horizontal pipe section 123 abuts against the side wall around the opening 11b of the drainage manhole body 11, thereby positioning the second horizontal pipe section 123 in the insertion direction.

[0039] A protruding portion 11c that protrudes outward from the drainage manhole body 11 may be provided on the side wall around the opening 11b of the drainage manhole body 11. In this case, the protruding portion 11c of the drainage manhole body 11 may be arranged cylindrically so as to surround the opening 11b, and the tip surface of the protruding portion 11c may be made flush with a flat surface. In this way, the tip surface of the protruding portion 11c of the drainage manhole body 11 can be in surface contact with the side surface (downstream side) of the protruding portion 123a of the second horizontal pipe section 123, so that the inflow pipe section 12 and the drainage manhole body 11 can be well connected without using a packing or the like.

[0040] In this embodiment, in order to facilitate the flow of wastewater and the like that has passed through the downstream opening 12b of the second horizontal pipe section 123 downstream together with the wastewater, the bottom of the drainage manhole body 11 may be located further below the pipe bottom of the second horizontal pipe section 123, i.e., the downstream pipe bottom of the inlet pipe section 12. In this case, the drainage manhole body 11 may be provided with an inclined section that slopes downward downstream from the lower end of the downstream opening 12b of the second horizontal pipe section 123 to the bottom of the drainage manhole body 11. In addition, the drainage manhole body 11 may be provided with a horizontal section that is connected to the inclined section and supports the second horizontal pipe section 123, and a support section that supports the horizontal section and is located below the opening 11b of the drainage manhole body 11.

[0041] The inclination of the inclined pipe section 122 may be set so that the difference in height between the bottom of the first horizontal pipe section 121 and the bottom of the second horizontal pipe section 123 is 23% or more of the inner diameter of the upstream piping (piping connected to the inflow pipe section 12 from the upstream side). The inclination of the inclined pipe section 122 may also be set so that the extension line (dashed line in FIG. 2) of the pipe axis (center axis) of the first horizontal pipe section 121 passes through the downstream opening 12b of the inflow pipe section 12 without intersecting the inner wall surface of the inclined pipe section 122. In other words, the difference in height between the bottom of the first horizontal pipe section 121 and the bottom of the second horizontal pipe section 123 may be set to less than 50% of the inner diameter of the inclined pipe section 122 (the inner diameter of the upstream pipe).

[0042] The outflow pipe section 13 may be integrally formed with the drainage basin body 11. The bottom of the drainage basin body 11 and the bottom of the outflow pipe section 13 may be located at approximately the same height. Although not shown, a pipe (downstream pipe on the sewer pipe side) constituting the drainage pipeline 1 is connected to the opening (downstream opening) of the outflow pipe section 13. Specifically, the outer diameter of the downstream pipe is approximately equal to the inner diameter of the opening side of the outflow pipe section 13, and the upstream end of the downstream pipe is inserted into the outflow pipe section 13. A step 13a is provided inside the outflow pipe section 13 along the inner circumference of the pipe, and the inner diameter of the outflow pipe section 13 upstream of the step 13a is smaller than the inner diameter of the opening side of the outflow pipe section 13, i.e., the outer diameter of the downstream pipe. As a result, the tip of the downstream pipe inserted into the outflow pipe section 13 abuts against the step 13a, thereby positioning the insertion direction of the downstream pipe.

[0043] The check valve 14 has a substantially disk-shaped valve body 141 configured to be able to close the downstream opening 12b of the inlet pipe section 12. The check valve 14 further has a support section 142 that rotatably supports the valve body 141, a rotating shaft 143 provided on the opposite side of the valve body 141 in the support section 142, and a bearing member 15 that supports the rotating shaft 143. An extension section 111 that extends toward the inside of the drainage basin body 11 along the outer circumferential top of the second horizontal pipe section 123 is provided above the opening 11b in the inner wall of the drainage basin body 11, and the bearing member 15 is fixed on the extension section 111 by a method such as bonding, screwing, or welding. The bearing member 15 may be fixed removably by being fitted into the extension section 111, for example. By making the bearing member 15 removable, it becomes easy to replace the bearing member 15 when it is damaged. The rotating shaft 143 supported by the bearing member 15 is disposed upstream of the center of gravity of the valve body 141. The extension portion 111 may be formed integrally with the drainage basin body 11.

[0044] The opening surface of the downstream opening 12b of the inflow pipe section 12 (second horizontal pipe section 123) is substantially a vertical surface, and the valve body 141 closes the downstream opening 12b substantially vertically along this vertical surface when no drainage is performed. That is, the angle that the disk shape of the valve body 141 makes with the vertical surface when closing the downstream opening 12b is substantially 0°. A valve seat surface 12c that can come into contact with the valve body 141 is provided on the downstream end surface of the inflow pipe section 12, that is, on the peripheral portion of the downstream opening 12b in the inflow pipe section 12. The valve seat surface 12c is configured to be able to come into contact with the valve body 141 when drainage backflows. The valve seat surface 12c may be provided in a downstream direction from the inner peripheral surface to the end surface of the inflow pipe section 12 (second horizontal pipe section 123). That is, the valve seat surface 12c may be a tapered surface (inclined surface). An annular packing 16 capable of coming into close contact with the valve seat surface 12 c of the inflow pipe portion 12 is provided on the outer circumferential surface of the valve body 141 .

[0045] In this embodiment, an invert section 11d having, for example, a semicircular cross section may be provided at the bottom of the drainage manhole body 11. The bottom of the invert section 11d and the bottom of the outflow pipe section 13 may be located at approximately the same height. The invert section 11d may be provided by extending from the bottom of the drainage manhole body 11 to the downstream opening 12b of the second horizontal pipe section 123. In this way, the invert 11d connects the inflow pipe section 12 and the outflow pipe section 13, making it possible to prevent sewage and the like from accumulating during drainage.

[0046] <Example of backflow prevention mass operation> When no drainage is being performed, the valve body 141 of the check valve 14 contacts the valve seat surface 12c of the inflow pipe section 12 to close the downstream opening 12b of the inflow pipe section 12. When the valve body 141 is closing the downstream opening 12b and wastewater flows out of the indoor drainage equipment 2, the wastewater that flows into the inflow pipe section 12 through the drainage pipe line 1 pushes open the valve body 141 that is in contact with the valve seat surface 12c of the inflow pipe section 12 by water pressure. As a result, the wastewater flows from the inflow pipe section 12 into the drainage manhole body 11, and the wastewater flows out of the check valve manhole 10 through the outflow pipe section 13. In addition, since the center of gravity of the valve body 141 is located downstream of the rotation axis 143, when the wastewater flows out of the inflow pipe section 12, the valve body 141 closes the downstream opening 12b again by its own weight.

[0047] On the other hand, even if the wastewater exceeds the drainage capacity of the sewer pipe due to heavy rain or the like and overflows and flows back up the drainage pipe 1, the downstream opening 12b of the inlet pipe section 12 is blocked by the valve body 141 of the check valve 14, so the wastewater will not enter the drainage pipe 1 upstream of the check valve 14. Therefore, it is possible to prevent the backflowing wastewater and the air compressed by this wastewater from spouting out of the indoor drainage equipment 2.

[0048] <Effects of the embodiment> According to the backflow prevention mass 10 of the present embodiment described above, the downstream pipe bottom is located lower than the upstream pipe bottom in the wastewater inflow pipe section 12 provided on the side wall of the drainage mass body 11. Therefore, the flow rate of the wastewater increases when the wastewater flows from the upstream side to the downstream side of the inflow pipe section 12, so that the valve body 141 of the backflow prevention valve 14 that blocks the downstream opening 12b of the inflow pipe section 12 is easily opened by the flow of the wastewater. Therefore, even if the amount of wastewater is small, the backflow prevention mass 10 can be prevented from being clogged by wastewater due to sewage or the like. In particular, the backflow prevention mass 10 of the present embodiment is useful when the flow gradient of the pipe connected from the upstream side to the inflow pipe section 12 is small and the flow rate of the wastewater in the pipe is small.

[0049] Furthermore, in the backflow prevention manhole 10 of this embodiment, the bottom of the drainage manhole body 11 may be located lower than the bottom of the downstream pipe of the inflow pipe section 12. This makes it possible to avoid a situation in which waste material or the like accumulates downstream of the valve body 141 of the backflow prevention valve 14 in the drainage manhole body 11, obstructing the opening of the valve body 141. This makes it possible to further prevent drainage blockages in the backflow prevention manhole 10 due to waste material or the like.

[0050] Furthermore, in the backflow prevention mass 10 of this embodiment, the height difference between the downstream pipe bottom and the upstream pipe bottom in the inflow pipe section 12 may be 23% or more of the inner diameter of the piping connected to the inflow pipe section 12 from the upstream side. In this way, the flow rate of the wastewater can be sufficiently increased when the wastewater flows from the upstream side to the downstream side of the inflow pipe section 12, making it easier for the valve body 141 of the backflow prevention valve 14 to open due to the flow of the wastewater. Therefore, the backflow prevention mass 10 can be further prevented from becoming clogged with wastewater due to sewage, etc.

[0051] In the backflow prevention mass 10 of this embodiment, the inflow pipe section 12 may include a first horizontal pipe section 121 that is disposed on the upstream side and has a horizontal or approximately horizontal pipe bottom, and an inclined pipe section 122 that is disposed downstream of the first horizontal pipe section 121 and has a pipe bottom that is inclined downward toward the downstream side. In this manner, the piping that is connected to the inflow pipe section 12 from the upstream side can be easily connected to the first horizontal pipe section 121 of the inflow pipe section 12.

[0052] Furthermore, in the backflow prevention tank 10 of this embodiment, the inflow pipe section 12 may further include a second horizontal pipe section 123 that is disposed downstream of the inclined pipe section 122, is connected to the drainage tank body 11, and has a horizontal or approximately horizontal pipe bottom. In this way, the second horizontal pipe section 123 of the inflow pipe section 12 can be easily attached to the side wall of the drainage tank body 11.

[0053] Furthermore, in the backflow prevention block 10 of this embodiment, the extension line of the pipe axis of the first horizontal pipe section 121 may pass through the downstream opening 12b of the inflow pipe section 12 without intersecting with the inner wall surface of the inclined pipe section 122. This makes it possible to avoid a situation in which wastewater flows from the upstream side to the downstream side of the inflow pipe section 12 and collides with the vicinity of the pipe apex (the apex of the pipe inner wall) of the inclined pipe section 122, causing a decrease in the flow rate of the wastewater. This makes it possible to realize a state in which the valve body 141 of the backflow prevention valve 14 is easily opened by the flow of wastewater.

[0054] In the backflow prevention mass 10 of this embodiment, the first horizontal pipe section 121, the inclined pipe section 122, and the second horizontal pipe section 123 may be integrally molded. In this way, the number of components of the backflow prevention mass 10 can be reduced, making it easier to assemble the backflow prevention mass 10.

[0055] Furthermore, in the backflow prevention tank 10 of this embodiment, the downstream side of the inflow pipe section 12 may be inserted into the drainage tank body 11. In this way, the configuration of the inflow pipe section 12 is simplified, and the backflow prevention tank 11 is easily assembled. Specifically, if the downstream end of the inflow pipe section 12 is to be brought into direct contact with the cylindrical side wall of the drainage tank body 11 without being inserted into the drainage tank body 11, the connection section of the inflow pipe section 12 with the drainage tank body 11 must be formed into a complex shape. In contrast, in this embodiment, as described above, the inflow pipe section 12 and the drainage tank body 11 can be satisfactorily connected without using a packing or the like.

[0056] In addition, in the backflow prevention mass 10 of this embodiment, the valve body 141 may be arranged to substantially vertically block the downstream opening 12b of the inflow pipe section 12 when no drainage is occurring, and a valve seat surface 12c configured to be able to abut against the valve body 141 when drainage backflows may be provided on the periphery of the downstream opening 12 of the inflow pipe section 12. In this way, the valve body 141 can be easily opened and closed when drainage is occurring, and the occurrence of a water seal failure in the drainage pipe line can be suppressed by preventing the situation in which air is forced to the upstream side when drainage backflow occurs. In this case, if the valve seat surface is provided in a downstream direction from the inner peripheral surface to the end surface of the inflow pipe section 12, the water stop effect of the valve body 141 can be reliably obtained even with a weaker force (water pressure) when drainage backflow occurs.

[0057] <Example> In the following, examples will be described. In these examples, a sweeping test of the backflow prevention tank 10 was conducted while changing the combination of the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section 12" and the "height difference between the bottom of the drainage tank body 11 and the downstream pipe bottom of the inflow pipe section 12" in the backflow prevention tank 10.

[0058] Specifically, as shown in Fig. 4, in the backflow prevention basin 10, four patterns of 0 mm, 10 mm, 20 mm, and 30 mm were set as the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section 12", and five patterns of 0 mm, 10 mm, 20 mm, 30 mm, and 40 mm were set as the "height difference between the bottom of the drainage basin main body 11 and the downstream pipe bottom of the inflow pipe section 12". In Fig. 4, the same components as those in the backflow prevention basin 10 shown in Fig. 2 are given the same reference numerals. In addition, due to the upstream piping (not shown) inserted into the first horizontal pipe section 121, the substantial pipe bottom of the first horizontal pipe section 121 (the substantial upstream pipe bottom of the inflow pipe section 12) becomes higher by the wall thickness of the upstream piping, but the dimensions shown in Fig. 4 take this wall thickness into consideration.

[0059] In the sweeping performance test, the sweeping performance was evaluated by whether or not the wastewater could pass through the backflow prevention basin 10 when flushing wastewater (such as simulated waste) from a water-saving toilet, which is an indoor drainage system 2, into the drainage pipe 1 shown in Figure 1.

[0060] The drainage pipeline 1 was composed of an indoor pipe consisting of a polyvinyl chloride pipe VU75 with an extension length of 1800 mm, and an outdoor pipe consisting of a polyvinyl chloride pipe VU100 with an extension length of 11700 mm. The backflow prevention manhole 10 and other drainage manholes 3A, 3B, and 3C were placed in the outdoor piping portion of the drainage pipeline 1. Specifically, the drainage manhole 3A was placed at a point 1300 mm downstream from the connection point between the indoor piping and the outdoor piping, the drainage manhole 3B was placed at a point 4400 mm downstream from the drainage manhole 3A, the drainage manhole 3C was placed at a point 1500 mm downstream from the drainage manhole 3B, and the backflow prevention manhole 10 was placed at a point 4500 mm downstream from the drainage manhole 3C. In addition, the flow gradient of the indoor piping is 1 / 100, a drop of 500 mm is provided between the indoor piping and the outdoor piping, the flow gradient of the outdoor piping up to drainage manhole 3C is 2 / 100, and the flow gradient from drainage manhole 3C to backflow prevention manhole 10 is 1 / 200.

[0061] In addition, in the sweeping performance test, as a general rule, a large flush of the water-saving toilet was performed once, and if the flowing matter did not reach the backflow prevention manhole 10 and became stuck along the way, if the location where the flowing matter was stuck was upstream of drainage manhole 3B, an additional large flush of the water-saving toilet was performed, and if the location where the flowing matter was stuck was at drainage manhole 3B or further downstream, an additional small flush of the water-saving toilet was performed until the flowing matter reached the backflow prevention manhole 10. The materials used for flushing were artificial dirt made from a PVA (polyvinyl alcohol) sponge (φ25, length 80 mm, specific gravity approximately 1.05) (hereinafter referred to as PVA artificial dirt) and single-piece toilet paper (one sheet is defined as three folds of 90 cm).As the "normal" amount, four half-cut pieces of PVA artificial dirt and two single-piece toilet paper were flushed, and as the "large" amount, six half-cut pieces of PVA artificial dirt, eight quarter-cut pieces of PVA artificial dirt, and eight single-piece toilet paper were flushed.

[0062] The results of the sweeping test for various combinations of the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section 12" and the "height difference between the bottom of the drainage manhole main body 11 and the downstream pipe bottom of the inflow pipe section 12" in the backflow prevention manhole 10 are shown in Table 1 below, expressed as "(number of times the flowing matter passed through the valve body 141 of the backflow prevention valve 14) / (number of tests)".

[0063] [Table 1]

[0064] As shown in Table 1, by positioning the downstream pipe bottom lower than the upstream pipe bottom in the inflow pipe section 12, the sweeping ability of the backflow prevention manhole 10 is improved. Furthermore, when the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section 12" is the same, the sweeping ability of the backflow prevention manhole 10 is further improved by positioning the bottom of the drainage manhole body 11 lower than the downstream pipe bottom of the inflow pipe section 12. In particular, by making the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section 12" about 25 mm or more, more preferably 30 mm or more, sufficient sweeping ability can be obtained even for "large amounts" of flowing material. In this embodiment, the inner diameter of the pipe (vinyl chloride pipe VU100) connected to the inlet pipe section 12 from the upstream side is 107 mm, so it can be seen that particularly excellent sweeping performance can be obtained by making the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inlet pipe section 12" at least approximately 23% of the inner diameter of the pipe connected to the inlet pipe section 12 from the upstream side.

[0065] As described above, if the flow gradient (1 / 200 in this embodiment) of the piping connected from the upstream side to the inflow pipe section 12 is small, the flow rate of the wastewater in the piping becomes small and the flowing material is likely to stagnate; however, the sweeping ability of the backflow prevention mass 10 can be improved by the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section 12."

[0066] If the "difference in height between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section 12" is set to about 50% or less of the outer diameter of the pipe connected to the inflow pipe section 12 from the upstream side, a general-purpose size joint can be used for the inflow pipe section 12, which has a cost advantage. Also, if the "difference in height between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section 12" is set to about 100% or less of the outer diameter of the pipe connected to the inflow pipe section 12 from the upstream side, it is possible to prevent the backflow prevention mass 10 from being buried deep in the ground, which has the advantage of improving workability.

[0067] In this embodiment, apart from the sweeping ability test described above, a retention test was conducted to evaluate whether or not a small amount of water flows into the drainage pipe 1 and the water stays upstream of the valve body 141 of the check valve 14 (whether or not the valve body 141 can be pushed open). Specifically, 100 cc of water was flowed from the drainage basin 3B, and it was evaluated whether the entire amount of 100 cc of water could pass through the downstream opening 12b of the inflow pipe section 12 without staying in front of the valve body 141. The retention test was conducted three times for each of two patterns: a state in which the valve body 141 was naturally closed after normal drainage, and a state in which the valve body 141 was pressed and closed by a human hand to simulate a backflow of drainage water.

[0068] As a result of the retention test, in normal drainage, all 100cc of water passed through the downstream opening 12b of the inlet pipe 12 regardless of whether the "difference in height between the downstream pipe bottom and the upstream pipe bottom of the inlet pipe 12" was 10mm, 20mm, or 30mm. On the other hand, when simulating a backflow of drainage, all 100cc of water passed through the downstream opening 12b of the inlet pipe 12 if the "difference in height between the downstream pipe bottom and the upstream pipe bottom of the inlet pipe 12" was 20mm or more.

[0069] In addition, in the case of a small amount of water, it was confirmed that the valve body 141 does not open due to the drainage speed given by the "difference in height between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section 12", but rather a small amount of water temporarily stays in front of the valve body 141, and the valve body 141 opens due to the resulting head pressure, allowing the water to pass through. From this, it was found that the "difference in height between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section 12" should be a height difference that creates a water depth that can provide sufficient head pressure to the valve body 141. In addition, it was found that in order to prevent a small amount of water from staying, it is more effective to shorten the length of the horizontal pipe section (second horizontal pipe section 123) in front of the downstream opening 12b in the inflow pipe section 12 as much as possible, rather than the size of the "difference in height between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section 12" itself.

[0070] (Other embodiments) In the above embodiment (including the working example, the same applies below), the backflow prevention mass 10 is provided in the drainage pipeline 1 configured in series. However, this is not limited to this, and the backflow prevention mass 10 may be provided in a drainage pipeline including multiple pipes configured in parallel using, for example, a drainage header or the like.

[0071] In addition, in the above embodiment, one each of the inlet pipe section 12 and the outlet pipe section 13 for drainage is provided on the side wall of the drainage manhole body 11. However, this is not limited to this, and multiple inlet pipe sections 12 and multiple outlet pipe sections 13 may be provided on the side wall of the drainage manhole body 11.

[0072] In the above embodiment, the inflow pipe section 12 is composed of the first horizontal pipe section 121, the inclined pipe section 122, and the second horizontal pipe section 123. However, the configuration of the inflow pipe section 12 is not particularly limited as long as the downstream pipe bottom of the inflow pipe section 12 is located lower than the upstream pipe bottom, in other words, as long as the lower end of the downstream opening 12b of the inflow pipe section 12 is located lower than the lower end of the upstream opening 12a. For example, the first horizontal pipe section and / or the second horizontal pipe section 123 may not be provided. Alternatively, a third horizontal pipe section may be provided midway through the inclined pipe section 122.

[0073] In addition, in the above embodiment, the inlet pipe section 12 and the drainage manhole body 11 are separate bodies, and the downstream side of the inlet pipe section 12 is inserted into the inside of the drainage manhole body 11, but instead, the downstream end of the inlet pipe section 12 may be attached to the side wall of the drainage manhole body 11, or the inlet pipe section 12 and the drainage manhole body 11 may be molded as a single unit.

[0074] A longitudinal sectional view of a modified example of the backflow prevention mass 10 is shown in Fig. 5. In Fig. 5, the same components as those of the backflow prevention mass 10 shown in Fig. 2 are given the same reference numerals. The modified example shown in Fig. 5 differs from the backflow prevention mass 10 shown in Fig. 2 in that the inlet pipe section 12 has a valve pipe 124 attached to the downstream side from the inside of the drainage mass body 11, and a valve seat surface 12c that can come into contact with the valve body 141 is provided on the downstream end face of the valve pipe 124. According to this modified example, the valve pipe 124 that is opened and closed by the valve body 141 is attached from the inside of the drainage mass body 11, so that the valve body 141 can be attached integrally with the valve pipe 124, making it easier to assemble the backflow prevention mass.

[0075] In the modified example shown in FIG. 5, the second horizontal pipe section 123 may be disposed upstream compared to the backflow prevention tank 10 shown in FIG. 2, and the valve pipe 124 may be connected horizontally to the second horizontal pipe section 123 from the downstream side, and the valve pipe 124 may be configured as a part of the second horizontal pipe section 123. An extension section 111 extending inward of the drainage tank body 11 may be provided on the inner wall around the opening 11b of the drainage tank body 11, and the valve pipe 124 may be supported by the extension section 111. The valve pipe 124 may be bonded to the cylindrical extension section 111 in a state where it is inserted into the extension section 111. The backflow prevention valve 14 (bearing member 15) may be attached to the top of the valve pipe 124. A recess 141a may be provided on the outer circumferential surface of the valve body 141, and a V-packing, for example, may be attached to the recess 141a as the packing 16. In this way, since the valve seat surface 12c is a tapered surface (inclined surface), the adhesion of the packing 16 to the valve seat surface 12c is improved, and the water blocking effect of the valve body 141 when wastewater backflows is further increased.

[0076] Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. Moreover, the above embodiments may be appropriately combined or substituted as long as the functionality of the subject matter of the present disclosure is not impaired. Furthermore, the descriptions "first", "second", ... described above are used to distinguish the words to which these descriptions are attached, and do not limit the number or order of the words. [Explanation of symbols]

[0077] 1 Drainage line 2 Indoor drainage equipment 3A, 3B, 3C drainage mass 10 Backflow prevention mass 11 Drainage basin body 11a, 11b opening 11c Protrusion 11d Inverter section 111 Extension section 12 Inflow pipe section 12a Upstream opening 12b Downstream opening 12c Valve seat surface 121 1st horizontal pipe section 121a Step 122 Inclined pipe section 123 2nd horizontal pipe section 123a Protrusion 124 Valve Pipe 13 Outlet pipe section 13a Step 14 Check valve 141 Valve body 141a Recess 142 Support part 143 Rotational Axis 15 Bearing materials 16 Packing

Claims

1. A backflow prevention block is provided in a drainage pipe that connects an indoor drainage system to a sewer pipe, and prevents wastewater flowing backward through the drainage pipe from entering the upstream side. A drainage basin body, A drainage inlet pipe portion and a drainage outlet pipe portion provided on a side wall of the drainage basin body; a check valve provided in the drainage basin body and having a valve body configured to be able to close a downstream opening of the inlet pipe portion; Equipped with The valve element of the check valve closes the downstream opening of the inlet pipe section by its own weight when no drainage is performed, A downstream pipe bottom of the inlet pipe section is located lower than an upstream pipe bottom of the inlet pipe section, The inflow pipe section includes at least a first horizontal pipe section disposed upstream and having a horizontal or substantially horizontal pipe bottom, and an inclined pipe section disposed downstream of the first horizontal pipe section and having a pipe bottom inclined downward toward the downstream side, The inlet pipe section further includes a second horizontal pipe section that is arranged downstream of the inclined pipe section, is connected to the drainage basin body, and has a horizontal or approximately horizontal pipe bottom. Backflow prevention mass.

2. The bottom of the drainage basin body is located below the downstream pipe bottom of the inlet pipe section. The backflow prevention mass according to claim 1 .

3. The height difference between the downstream pipe bottom and the upstream pipe bottom in the inlet pipe section is 23% or more of the inner diameter of the pipe connected to the inlet pipe section from the upstream side. A backflow prevention mass according to claim 1 or 2.

4. The first horizontal pipe section and the inclined pipe section are integrally formed, The inlet pipe portion is inserted into the drainage basin body, A valve seat surface capable of coming into contact with the valve body is provided on a downstream end surface of the inlet pipe portion. A backflow prevention mass according to any one of claims 1 to 3.

5. An extension line of a pipe axis of the first horizontal pipe section passes through the downstream opening of the inlet pipe section without intersecting an inner wall surface of the inclined pipe section. A backflow prevention mass according to any one of claims 1 to 4.

6. The downstream side of the inlet pipe portion is inserted into the inside of the drainage basin body, The valve body vertically closes the downstream opening of the inlet pipe portion when no drainage is performed, A valve seat surface configured to be able to come into contact with the valve body when wastewater backflows is provided on a peripheral portion of the downstream opening of the inflow pipe portion. A backflow prevention mass according to any one of claims 1 to 5.

7. The valve seat surface is provided in a downstream direction so as to widen from the inner circumferential surface to the end surface of the inlet pipe portion. The backflow prevention mass according to claim 6.

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