JP7565866B2 - Backflow prevention mass - Google Patents

Description

This disclosure relates to a backflow prevention block that is installed in a drainage pipe that connects indoor drainage equipment such as a toilet to a sewer pipe, and prevents wastewater that flows backward through the drainage pipe from entering the upstream side.

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 garbage and other waste in the drainage pipe.

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 drainage capacity of the sewer pipe is exceeded and the overflowing wastewater passes through the drainage manhole and flows back up the drainage pipe, causing problems such as the backflowing wastewater spraying out into the building from the indoor drainage equipment connected to the drainage pipe, or the air compressed by the drainage causing sealed water to spray out into the building.

In response to this, in order to prevent wastewater that has backed up from the sewer pipes from passing through the drainage manhole and gushing 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.

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 that it inclines 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 normally 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, preventing the wastewater from flowing back through the drainage basin into the upstream drainage pipe.

JP 2010-126888 A

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, under normal circumstances the valve body 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.

In view of the above, the present disclosure aims to provide a backflow prevention basin that prevents wastewater from flowing backward through a drainage pipe from entering the upstream side, and that can prevent drainage blockages caused by wastewater, etc., even when the amount of drainage is small.

In order to achieve the above object, the 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, which prevents 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, the downstream pipe bottom of the inlet pipe section being located lower than the upstream pipe bottom of the inlet pipe section.

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 the valve body of the check valve that blocks the downstream opening of the inlet pipe section is more likely to open due to the flow of the wastewater. Therefore, even if the amount of wastewater is small, it is possible to prevent the backflow prevention manhole from becoming clogged with sewage or the like.

The second aspect of the present disclosure is the first aspect, in which the bottom of the drainage manhole body is a backflow prevention manhole located below the downstream pipe bottom of the inlet pipe section.

According to the second aspect, it is possible to prevent waste matter from accumulating downstream of the valve body of the check valve in the drainage manhole body, thereby preventing the valve body from opening, thereby further preventing drainage blockages caused by waste matter.

A third aspect of the present disclosure is a backflow prevention mass according to the first or second aspect, in which 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.

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. This makes it easier for the valve element of the check valve to open due to the flow of the wastewater, further preventing the drain from becoming clogged with sewage or the like.

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

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, making it possible to attach the valve body integrally with the valve pipe, facilitating assembly of the backflow prevention manhole.

A fifth aspect of the present disclosure is a backflow prevention mass in any one of the first to fourth aspects, in which the inflow pipe section includes at least a first horizontal pipe section disposed upstream and having a horizontal or nearly horizontal pipe bottom, and an inclined pipe section disposed downstream of the first horizontal pipe section and having a pipe bottom that is inclined downward toward the downstream side.

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.

The sixth aspect of the present disclosure is a backflow prevention mass in the fifth aspect, in which 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 that can come into contact with the valve body is provided on the downstream end face of the inlet pipe section.

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.

A seventh aspect of the present disclosure is a backflow prevention tank according to the fifth or sixth aspect, in which the inlet pipe section is disposed downstream of the inclined pipe section, is connected to the drainage tank body, and further includes a second horizontal pipe section whose bottom is horizontal or approximately horizontal.

According to the seventh aspect, the second horizontal pipe section of the inlet pipe section can be easily attached to the side wall of the drainage manhole body.

The eighth aspect of the present disclosure is a backflow prevention mass according to any one of the fifth to seventh aspects, in which 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 with the inner wall surface of the inclined pipe section.

According to the eighth aspect, it is possible to avoid a situation in which wastewater flow speed is reduced due to collision with the apex of the inclined pipe section as it flows from the upstream side to the downstream side of the inlet pipe section, thereby realizing a state in which the valve body of the check valve is easily opened by the flow of wastewater.

A ninth aspect of the present disclosure is a backflow prevention mass in any one of the first to eighth aspects, in which the downstream side of the inflow pipe section is inserted into the inside of the drainage mass body, the valve body vertically blocks the downstream opening of the inflow pipe section when no drainage is occurring, and a valve seat surface is provided on the periphery of the downstream opening of the inflow pipe section so that it can come into contact with the valve body when drainage backflows.

According to the ninth aspect, the configuration of the inlet pipe section is simplified, making it easier to assemble the backflow prevention mass. In addition, it is easier 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 failure in the drainage pipe.

The tenth aspect of the present disclosure is the ninth aspect, in which the valve seat surface is a backflow prevention mass that is divergent in the downstream direction from the inner circumferential surface to the end surface of the inlet pipe section.

According to the tenth aspect, when backflow of wastewater occurs, the valve body can reliably achieve a water-stopping effect even with a weaker force (water pressure).

According to the present disclosure, a backflow prevention basin that prevents wastewater from flowing backward through a drainage pipe from entering the upstream side can prevent drainage blockages caused by wastewater, etc., even when the amount of wastewater is small.

FIG. 1 is a diagram showing an example of a drainage pipeline in which a backflow prevention block according to an embodiment is provided. FIG. 2 is a vertical cross-sectional view of the backflow prevention mass according to the embodiment. 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 the vicinity thereof. Figure 4 is a cross-sectional view showing the difference in elevation between the downstream pipe bottom and the upstream pipe bottom of the inflow pipe section, and the difference in elevation between the bottom of the drainage manhole body and the downstream pipe bottom of the inflow pipe section in a backflow prevention manhole of the embodiment. FIG. 5 is a vertical cross-sectional view of a backflow prevention mass according to a modified example.

(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.

<Example of drainage pipe configuration>
The backflow prevention basin 10 of this embodiment is provided in a drainage pipeline 1 connecting 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 basins 3A, 3B, 3C may be provided between the indoor drainage facility 2 and the backflow prevention basin 10 in the drainage pipeline 1 to remove and inspect filth such as garbage in the drainage pipeline 1. The piping constituting the drainage pipeline 1 is, for example, a polyvinyl chloride pipe VU100 having 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.

<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 drainage 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.

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, for example, about 50 to 300 mm. By inserting an adjuster or a 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.

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 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 to the inside of the drainage manhole body 11.

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 downstream pipe bottom of the inflow pipe section 12 is located lower than the upstream pipe bottom of the inflow pipe section 12.

Although not shown, the upstream opening 12a of the inlet pipe section 12 (first horizontal pipe section 121) is connected to a pipe (upstream pipe on the indoor drainage equipment 2 side) that constitutes 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 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, thereby positioning the upstream pipe in the insertion direction.

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 from the opening 11b. That is, the downstream opening 12b of the inlet 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 insertion direction of the second horizontal pipe section 123.

The sidewall around the opening 11b of the drainage manhole body 11 may be provided with a protruding portion 11c that protrudes outward from the drainage manhole body 11. In this case, the protruding portion 11c of the drainage manhole body 11 may be arranged cylindrically 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.

In this embodiment, in order to facilitate the flow of wastewater and other materials that have 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 positioned further below the bottom of the second horizontal pipe section 123, i.e., the downstream 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 connects to the inclined section and supports the second horizontal pipe section 123, and a support section that supports the horizontal section and is positioned below the opening 11b of the drainage manhole body 11.

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 pipe (the pipe 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).

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, the opening (downstream opening) of the outflow pipe section 13 is connected to a pipe (downstream pipe on the sewer pipe side) that constitutes the drainage pipeline 1. 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. Inside the outflow pipe section 13, a step 13a is provided 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.

The check valve 14 has a substantially disk-shaped valve body 141 that is 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 periphery 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 gluing, screwing, or welding. The bearing member 15 may also be removably fixed by being fitted into the extension section 111. By making it removable, the bearing member 15 can be easily replaced when it is damaged. The rotating shaft 143 supported by the bearing member 15 is positioned upstream of the center of gravity of the valve body 141. The extension portion 111 may be molded integrally with the drainage basin body 11.

The opening surface of the downstream opening 12b of the inlet pipe section 12 (second horizontal pipe section 123) is substantially a vertical surface, and the valve body 141 blocks 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 blocking the downstream opening 12b is substantially 0°. A valve seat surface 12c that can abut against the valve body 141 is provided on the downstream end surface of the inlet pipe section 12, that is, the peripheral portion of the downstream opening 12b in the inlet pipe section 12. The valve seat surface 12c is configured to be able to abut against 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 inlet pipe section 12 (second horizontal pipe section 123). That is, the valve seat surface 12c may be a tapered surface (inclined surface). An annular gasket 16 that can be fitted tightly to the valve seat surface 12c of the inlet pipe section 12 is provided on the outer circumferential surface of the valve body 141.

In this embodiment, an invert section 11d having 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, preventing sewage and the like from accumulating during drainage.

<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, if wastewater flows out of the indoor drainage system 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 basin main body 11, and the wastewater flows out of the check valve 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.

On the other hand, even if the drainage capacity of the sewer pipe is exceeded due to heavy rain or the like and the overflowing drainage water 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 backflow prevention valve 14, so the drainage water will not enter the drainage pipe 1 upstream of the backflow prevention valve 14. Therefore, the backflowing drainage water and the air compressed by this drainage water can be prevented from spraying out of the indoor drainage equipment 2.

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.

In addition, in the backflow prevention manhole 10 of this embodiment, the bottom of the drainage manhole body 11 may be located lower than the downstream pipe bottom of the inlet pipe section 12. In this way, it is possible to avoid a situation in which waste matter accumulates downstream of the valve body 141 of the backflow prevention valve 14 in the drainage manhole body 11, preventing the valve body 141 from opening. This further prevents drainage blockages caused by waste matter in the backflow prevention manhole 10.

In addition, 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 occurrence of wastewater clogging due to sewage and the like in the backflow prevention mass 10 can be further suppressed.

In addition, in the backflow prevention mass 10 of this embodiment, the inflow pipe section 12 may include a first horizontal pipe section 121 that is located upstream and has a horizontal or nearly horizontal pipe bottom, and an inclined pipe section 122 that is located downstream of the first horizontal pipe section 121 and has a pipe bottom that is inclined downward toward the downstream side. In this way, 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.

In addition, in the backflow prevention manhole 10 of this embodiment, the inflow pipe section 12 may further include a second horizontal pipe section 123 that is located downstream of the inclined pipe section 122, is connected to the drainage manhole 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 manhole body 11.

In addition, in the backflow prevention mass 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 inlet pipe section 12 without intersecting with the inner wall surface of the inclined pipe section 122. In this way, it is possible to avoid a situation in which wastewater collides with the vicinity of the pipe top (top of the pipe inner wall) of the inclined pipe section 122 when flowing from the upstream side to the downstream side of the inlet pipe section 12, resulting in a decrease in the flow rate of the wastewater. Therefore, it is 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.

In addition, 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.

In addition, in the backflow prevention basin 10 of this embodiment, the downstream side of the inflow pipe section 12 may be inserted into the drainage basin body 11. In this way, the configuration of the inflow pipe section 12 is simplified, making it easier to assemble the backflow prevention basin 11. 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 basin body 11 without being inserted into the drainage basin body 11, the connection section of the inflow pipe section 12 with the drainage basin 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 basin body 11 can be well connected without using a packing or the like.

In addition, in the backflow prevention mass 10 of this embodiment, the valve body 141 substantially vertically blocks the downstream opening 12b of the inlet 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 peripheral portion of the downstream opening 12 of the inlet 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 upstream 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 inlet 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.

<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.

Specifically, as shown in FIG. 4, in the backflow prevention basin 10, four patterns of 0 mm, 10 mm, 20 mm, and 30 mm are 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 are set as the "height difference between the bottom of the drainage basin body 11 and the downstream pipe bottom of the inflow pipe section 12." Note that 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 pipe (not shown) inserted into the first horizontal pipe section 121, the actual pipe bottom of the first horizontal pipe section 121 (the actual upstream pipe bottom of the inflow pipe section 12) becomes higher by the thickness of the upstream pipe, but the dimensions shown in FIG. 4 take this thickness into consideration.

In the sweeping test, the sweeping performance was evaluated by whether or not the wastewater could pass through the backflow prevention basin 10 when the wastewater (artificial waste, etc.) was flushed together with the wastewater from a water-saving toilet, which is an indoor drainage system 2, in the drainage pipe 1 shown in Figure 1.

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 1300 mm downstream from the connection point between the indoor piping and the outdoor piping, the drainage manhole 3B was placed 4400 mm downstream from the drainage manhole 3A, the drainage manhole 3C was placed 1500 mm downstream from the drainage manhole 3B, and the backflow prevention manhole 10 was placed 4500 mm downstream from the drainage manhole 3C. In addition, the flow gradient of the indoor piping is 1/100, there is a drop of 500 mm between the indoor piping and the outdoor piping, the flow gradient of the outdoor piping up to the drainage manhole 3C is 2/100, and the flow gradient from the drainage manhole 3C to the backflow prevention manhole 10 is 1/200.

In addition, in the sweeping test, as a general rule, a large drain was performed once from the water-saving toilet, and if the flow-through material did not reach the backflow prevention manhole 10 and became stuck along the way, if the location where the flow-through material was stuck was upstream of drainage manhole 3B, an additional large drain was performed from the water-saving toilet, and if the location where the flow-through material was stuck was at drainage manhole 3B or further downstream, an additional small drain was performed from the water-saving toilet until the flow-through material reached the backflow prevention manhole 10. The materials used for the flushing were artificial dirt made from a PVA (polyvinyl alcohol) sponge (φ25, length 80 mm, specific gravity approximately 1.05) (hereafter referred to as PVA artificial dirt) and single toilet paper (one sheet is 3 folds per 90 cm). As the "normal" amount, four 1/2 cut pieces of PVA artificial dirt and two single toilet paper sheets were flushed, and as the "large" amount, six 1/2 cut pieces of PVA artificial dirt, eight 1/4 cut pieces of PVA artificial dirt, and eight single toilet paper sheets were flushed.

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 tank body 11 and the downstream pipe bottom of the inflow pipe section 12" in the backflow prevention tank 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)".

As shown in Table 1, by positioning the downstream pipe bottom lower than the upstream pipe bottom in the inlet pipe section 12, the sweeping ability of the backflow prevention manhole 10 is improved. In addition, when the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inlet 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 inlet pipe section 12. In particular, by making the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inlet 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 properties can be obtained by making the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inlet pipe section 12" approximately 23% or more of the inner diameter of the pipe connected to the inlet pipe section 12 from the upstream side.

As described above, if the flow gradient of the pipe connected from the upstream side to the inlet pipe section 12 (1/200 in this embodiment) is small, the flow rate of the wastewater in the pipe becomes small and the flowing material is likely to become stagnant, but the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inlet pipe section 12" can improve the sweeping ability of the backflow prevention mass 10.

In addition, if the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inlet pipe section 12" is set to about 50% or less of the outer diameter of the pipe connected to the inlet pipe section 12 from the upstream side, a general-purpose size joint can be used for the inlet pipe section 12, which has a cost advantage. In addition, if the "height difference between the downstream pipe bottom and the upstream pipe bottom of the inlet pipe section 12" is set to about 100% or less of the outer diameter of the pipe connected to the inlet pipe section 12 from the upstream side, the depth to which the backflow prevention mass 10 is buried in the ground can be prevented from increasing, which has the advantage of improving workability.

In this embodiment, in addition to the sweeping test described above, a retention test was conducted to evaluate whether a small amount of water flowing into the drainage pipeline 1 would remain upstream of the valve body 141 of the check valve 14 (whether the valve body 141 could be pushed open). Specifically, 100 cc of water was flowed from the drainage basin 3B, and an evaluation was conducted as to whether the entire 100 cc of water could pass through the downstream opening 12b of the inlet pipe section 12 without remaining 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 down by a human hand to close the valve body 141, simulating a backflow of drainage water.

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

In addition, in the case of a small amount of water, the valve body 141 does not open due to the drainage speed given by the "difference in height between the downstream and upstream pipe bottoms of the inlet pipe section 12", but rather a small amount of water temporarily stays in front of the valve body 141, and the resulting head pressure opens the valve body 141 to allow the water to pass through. From this, it was found that the "difference in height between the downstream and upstream pipe bottoms of the inlet pipe section 12" only needs to 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 inlet pipe section 12 as much as possible, rather than the size of the "difference in height between the downstream and upstream pipe bottoms of the inlet pipe section 12" itself.

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 a drainage header or the like.

In addition, in the above embodiment, one inlet pipe section 12 and one outlet pipe section 13 for drainage are 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.

In the above embodiment, the inflow pipe section 12 is composed of a first horizontal pipe section 121, an inclined pipe section 122, and a 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 do not need to be provided. Alternatively, a third horizontal pipe section may be provided midway through the inclined pipe section 122.

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.

A vertical cross-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 in 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 from the inside of the drainage mass body 11 on the downstream side, and the downstream end face of the valve pipe 124 is provided with a valve seat surface 12c that can abut against the valve body 141. 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.

In the modified example shown in FIG. 5, the second horizontal pipe section 123 may be arranged upstream compared to the backflow prevention basin 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 to the inside of the drainage basin body 11 may be provided on the inner wall around the opening 11b in the drainage basin 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 cylindrical 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, because the valve seat surface 12c is a tapered surface (inclined surface), the packing 16 adheres better to the valve seat surface 12c, and the water-stopping effect of the valve body 141 when wastewater backflows is further increased.

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. Furthermore, the above embodiments may be combined or substituted as appropriate as long as the functionality of the subject matter of this disclosure is not impaired. Furthermore, the descriptions "first," "second," etc. 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.

REFERENCE SIGNS LIST 1 drainage pipeline 2 indoor drainage equipment 3A, 3B, 3C drainage manhole 10 backflow prevention manhole 11 drainage manhole body 11a, 11b opening 11c protruding portion 11d invert portion 111 extension portion 12 inlet pipe portion 12a upstream opening 12b downstream opening 12c valve seat surface 121 first horizontal pipe portion 121a step 122 inclined pipe portion 123 second horizontal pipe portion 123a protruding portion 124 valve pipe 13 outflow pipe portion 13a step 14 backflow prevention valve 141 valve body 141a recess 142 support portion 143 rotating shaft 15 bearing member 16 packing

Claims (9)

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 section,
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 inlet pipe section includes at least a valve pipe attached from the inside of the drainage basin body on the downstream side,
A valve seat surface capable of coming into contact with the valve body is provided on a downstream end surface of the valve pipe .
Backflow prevention mass. 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 . 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.
The backflow prevention mass according to claim 1 or 2. 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 backflow prevention mass according to any one of claims 1 to 3 . 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.
The backflow prevention mass according to claim 4 . 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.
A backflow prevention mass according to claim 4 or 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 4 to 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 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 8 .

Images