Backflow prevention basin

Abstract

To easily replace a valve body of a backflow prevention basin at a low cost.SOLUTION: A backflow prevention basin 10 is installed in a drainage pipeline that connects an indoor drainage system to a sewer line. The backflow prevention basin 10 comprises a drain basin main body 11, an inspection port 11a open at the top of the drain basin main body 11, a drainage inflow pipe portion 12 and an outflow pipe portion 13 provided on the side wall of the drain basin main body 11, and a valve body 14 configured to be able to close a downstream opening 12b of the inflow pipe portion 12. A pivot portion 15 is provided on the downstream end of the inflow pipe portion 12. The valve body 14 is rotatably held by the pivot portion 15. The valve body 14 includes a valve main body 141, a rotating shaft portion 143 provided on the valve main body 141, and a pivoted portion 144 provided at the end of the rotating shaft portion 143. The pivoted portion 144 is detachably held by the pivot portion 15.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

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

[0003] When a large amount of rainwater flows into a sewer pipe in a short period of time due to a typhoon or the like, the drainage capacity of the sewer pipe may be exceeded and the overflowing wastewater may backflow up the drainage pipe. Patent Documents 1 to 3 disclose backflow prevention manholes that have a backflow prevention valve attached to the inlet opening inside the drainage manhole to prevent wastewater that has backflowed from the sewer pipe from passing through the drainage manhole and spouting out of the indoor drainage equipment. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-261222 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-126888 [Patent Document 3] Japanese Patent Application Publication No. 2018-204197 Summary of the Invention [Problem to be solved by the invention]

[0005] In backflow prevention tanks, the backflow prevention valve wears over many years of use, reducing its ability to prevent backflow of wastewater, or the operating mechanism of the backflow prevention valve becomes impaired, which can prevent normal drainage.In contrast, the conventional backflow prevention tanks disclosed in Patent Documents 1 to 3 allow the backflow prevention valve to be replaced.

[0006] However, in the backflow prevention mass of Patent Document 1, replacing the check valve requires attaching and detaching a nut deep inside the mass body, making it difficult to replace the check valve. Furthermore, the method of fixing the check valve in Patent Document 1 requires fitting a ring-shaped member onto a vertically extending shaft, making accurate positioning difficult and creating the risk of a gap between the valve seat and the valve body. Furthermore, the backflow prevention masses of Patent Documents 2 and 3 require a special valve body retaining member to enable replacement of the check valve, which increases the manufacturing costs of the backflow prevention mass.

[0007] In view of the above, an object of the present disclosure is to enable the valve body in a backflow prevention mass to be replaced easily and at low cost. [Means for solving the problem]

[0008] To achieve the above-mentioned object, a first aspect of the present disclosure is a backflow prevention manhole installed in a drainage pipe connecting an indoor drainage system to a sewer pipe, preventing wastewater flowing backward through the drainage pipe from entering the upstream side. The backflow prevention manhole includes a drainage manhole body, an inspection hatch opening at the top of the drainage manhole body, inlet and outlet pipes for wastewater provided on the side wall of the drainage manhole body, and a valve body configured to close the downstream opening of the inlet pipe. At least the downstream end of the inlet pipe protrudes into the drainage manhole body. A pivotal support is provided on the downstream end of the inlet pipe, and the valve body is rotatably held on the pivotal support. The valve body includes a valve body, a pivotal shaft provided on the valve body, and a pivotable support part provided at the end of the pivotal shaft and detachably held on the pivotal support part. The valve body can be replaced through the inspection hatch by removing the pivotal support part from the pivotal support part.

[0009] According to the first aspect, a support part for rotatably holding the valve element is provided on the downstream end of the inlet pipe part that protrudes into the drainage manhole body. Furthermore, a supported part that is detachably held on the support part is provided at the end of the pivot part of the valve element. Therefore, the valve element can be easily replaced through the inspection hatch by simply removing the supported part from the support part. Furthermore, because the valve element can be replaced simply by making the supported part detachable from the support part, increases in manufacturing costs can be suppressed.

[0010] In a second aspect of the present disclosure, in the first aspect, the pivot shaft portion includes a substantially cylindrical shaft member and a shaft insertion portion into which the shaft member is inserted. The supported portion is provided at an end of the shaft member. The shaft insertion portion is formed integrally with the valve body and is rotatable with the shaft member as a support.

[0011] According to the second aspect, the supported portion does not generally rotate together with the shaft member, which reduces the frictional force generated between the supported portion and the supporting portion, thereby suppressing wear on the supporting portion, which is difficult to replace. Furthermore, compared to a configuration in which the supported portion rotates directly at the supporting portion, the diameter of the shaft member, which is the shaft supporting the rotation of the valve body, can be made smaller, thereby reducing the contact area of ​​the shaft. This reduces the frictional force between the shaft member and the shaft insertion portion, making it easier for the valve body to rotate.

[0012] A third aspect of the present disclosure is the second aspect, wherein the supported portion is a cap-shaped member having a hole into which an end of the shaft member is fitted.

[0013] According to the third aspect, the supported portion can be more easily attached to the shaft member than when the supported portion is a doughnut-shaped member having a through hole, thereby improving the assembly accuracy of the backflow prevention mass.

[0014] A fourth aspect of the present disclosure is the second or third aspect, wherein the supported portion and the shaft insertion portion are spaced apart.

[0015] According to the fourth aspect, compared to when the supported portion and the shaft insertion portion abut, friction when the shaft insertion portion rotates can be reduced, and the supported portion can be prevented from rotating (rotating together) with the shaft insertion portion, thereby preventing increased wear between the supported portion and the shaft insertion portion.

[0016] A fifth aspect of the present disclosure is any one of the first to fourth aspects, wherein the supporting portion is provided with a recess into which the supported portion is inserted. The recess has a tapered shape that widens toward an upper end, and a portion of the bottom of the recess that abuts against the supported portion has an arc shape.

[0017] According to the fifth aspect, the opening side of the recess provided in the pivotal support part is widened, which makes it easier to assemble and remove the pivotally supported part. Also, even if the position of the pivotally supported part shifts from the bottom of the recess (the abutment part) due to pressure on the valve body when suppressing backflow of wastewater, the pivotally supported part will tend to return to its original abutment part naturally.

[0018] A sixth aspect of the present disclosure is any one of the first to fifth aspects, wherein the valve body has a gripped portion for gripping the valve body during replacement.

[0019] According to the sixth aspect, when replacing the valve body, the supported part can be more easily removed and attached to the supporting part.

[0020] A seventh aspect of the present disclosure is any one of the first to sixth aspects, wherein the valve body closes the downstream opening of the inlet pipe section vertically when no drainage is performed.

[0021] According to the seventh aspect, the valve body can be easily opened and closed when draining water. Also, compared to when the valve body is tilted when no draining water is being used, the valve body is less likely to come off when backflow of drained water occurs.

[0022] An eighth aspect of the present disclosure is any one of the first to seventh aspects, wherein the hardness of the constituent material of the supported portion is lower than the hardness of the constituent material of the supporting portion.

[0023] According to the eighth aspect, since the supported part is made of a softer material than the supporting part, the supported part can be easily removed from the supporting part, which makes it easier to replace the valve element. Furthermore, wear on the supporting part, which is difficult to replace, can be reduced when assembling the supported part to the supporting part, when the valve element is operating, when the valve element is being replaced, etc.

[0024] A ninth aspect of the present disclosure is any one of the first to eighth aspects, wherein the inlet pipe section has a valve pipe attached to the downstream side from inside the drainage manhole body, the pivot support section is provided on the downstream end of the valve pipe, and the valve body is configured to be able to close a downstream opening of the valve pipe.

[0025] According to the ninth 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. [Effects of the Invention]

[0026] According to the present disclosure, the valve body in the backflow prevention mass can be replaced easily and at low cost. [Brief explanation of the drawings]

[0027] [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. [Figure 2] FIG. 2 is a vertical cross-sectional view of the backflow prevention tank according to the embodiment. [Figure 3] 3 is a perspective view showing the valve body and the pivot support portion of the backflow prevention mass shown in FIG. 2. FIG. [Figure 4] 4 is a perspective view showing the valve body of the backflow prevention mass shown in FIG. 2 removed from the pivot support portion and disassembled. [Figure 5] 5 is a plan view showing the valve body and the pivot support portion of the check valve shown in FIG. 2. FIG. [Figure 6] 6 is a cross-sectional view showing a state in which a supported portion is attached to the end of the shaft member of the pivot shaft portion of the valve body of the backflow prevention mass shown in FIG. 2. FIG. [Figure 7] FIG. 7 is a perspective view showing a part of the valve body and the pivotal support part of the backflow prevention mass according to the first modification. [Figure 8] FIG. 8 is a vertical cross-sectional view of a backflow prevention mass according to the second modification. DETAILED DESCRIPTION OF THE INVENTION

[0028] (Embodiment) A backflow prevention mass according to an embodiment of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to the following embodiment, and various modifications are possible within the scope of the technical concept of the present disclosure.

[0029] <Drainage pipe> The backflow prevention manhole 10 of this embodiment is provided in a drainage pipeline 1 that connects an indoor drainage system 2, such as a toilet, to a sewer pipe (not shown), as shown in FIG. 1 . The backflow prevention manhole 10 prevents wastewater flowing backward through the drainage pipeline 1 from entering the upstream side. Other drainage manholes 3A, 3B, and 3C, for example, may be provided in the drainage pipeline 1 between the indoor drainage system 2 and the backflow prevention manhole 10 to remove waste such as garbage in the drainage pipeline 1 and to inspect the drainage pipeline 1. The piping that constitutes the drainage pipeline 1 may be, for example, a polyvinyl chloride pipe. The drainage pipeline 1 may have a gentle downward slope downstream.

[0030] <Backflow prevention tank> 2, the backflow prevention manhole 10 includes a drainage manhole body 11, an inspection hatch 11a opening at the top of the drainage manhole body 11, a drainage inlet pipe 12 and an outlet pipe 13 provided on the side wall of the drainage manhole body 11, and a valve body 14 configured to be able to close the downstream opening 12b of the inlet pipe 12. The backflow prevention manhole 10 may be made of a synthetic resin such as polyvinyl chloride.

[0031] The inspection hatch 11a has a circular shape with a diameter of, for example, about 50 to 300 mm. By inserting a height adjuster or a lid (not shown) into the inspection hatch 11a, the backflow prevention tank 10 can be exposed to the ground surface, allowing inspection and maintenance of the backflow prevention tank 10.

[0032] 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, a second horizontal pipe section 123 arranged downstream of the inclined pipe section 122, and a valve pipe 124 arranged downstream of the second horizontal pipe section 123. The first horizontal pipe section 121, the inclined pipe section 122, and the second horizontal pipe section 123 may be integrally molded. The valve pipe 124 is attached from the inside of the drainage manhole body 11 and is connected horizontally to the second horizontal pipe section 123. A valve seat surface 12c that can abut against the valve element 14 is provided on the downstream end face of the valve pipe 124.

[0033] 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.

[0034] 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 system 2 side) that constitutes the drainage pipeline 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 first horizontal pipe section 121 at the boundary with 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 water. 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.

[0035] The outer diameter of the second horizontal pipe section 123 is approximately equal to the diameter of the opening 11b of the drainage manhole main body 11. The downstream end of the second horizontal pipe section 123 may be connected to the upstream end of the valve pipe 124, for example, at the position of the opening 11b. A cylindrical section 11c that protrudes outward from the drainage manhole main body 11 to surround the opening 11b may be provided on the side wall around the opening 11b of the drainage manhole main body 11, and the second horizontal pipe section 123 may be inserted into the cylindrical section 11c. In this case, a protrusion 123a may be provided along the outer periphery of the second horizontal pipe section 123 at the boundary with the inclined pipe section 122. When the second horizontal pipe section 123 is inserted into the cylindrical section 11c, the protrusion 123a may abut against the tip of the cylindrical section 11c, thereby positioning the second horizontal pipe section 123. Furthermore, if the tip surface of the tubular portion 11c is made flush and flat, the tip surface of the tubular portion 11c can be in surface contact with the protrusion portion 123a, so that the inlet pipe portion 12 (second horizontal pipe portion 123) and the drainage manhole main body 11 can be well connected without using a gasket or the like.

[0036] The valve pipe 124, i.e., at least the downstream end of the inlet pipe section 12, protrudes into the inside of the drainage manhole body 11. The outer diameter of the valve pipe 124 is approximately equal to the diameter of the opening 11b of the drainage manhole body 11. An extension section 111 extending into the inside of the drainage manhole body 11 may be provided on the inner wall around the opening 11b of the drainage manhole 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 while inserted into the extension section 111.

[0037] The outflow pipe section 13 may be integrally molded with the drainage manhole main body 11. The bottom of the drainage manhole main body 11 and the bottom of the outflow pipe section 13 may be located at approximately the same height. Although not shown, a pipe (the downstream pipe on the sewer pipe side) that constitutes 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 along the inner circumference of the outflow pipe section 13, 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 downstream pipe in the insertion direction.

[0038] In this embodiment, in order to facilitate the flow of wastewater downstream after passing through the downstream opening 12b of the inlet pipe section 12 (valve pipe 124), the bottom of the drainage manhole body 11 may be positioned further below the bottom of the valve pipe 124, 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 valve pipe 124 to the bottom of the drainage manhole body 11. The drainage manhole body 11 may also be provided with a horizontal section that connects to the inclined section and supports the valve pipe 124, and a support section that supports the horizontal section and is positioned below the opening 11b of the drainage manhole body 11.

[0039] In addition, an invert section 11d having, for example, a semicircular cross section may be provided at the bottom of the drainage manhole main 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 extending from the bottom of the drainage manhole main body 11 to the downstream opening 12b of the valve pipe 124. In this way, the invert 11d connects the inflow pipe section 12 and the outflow pipe section 13, thereby preventing sewage and the like from accumulating during drainage.

[0040] 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 (i.e., the bottom of the valve pipe 124) is approximately ¼ or more of the inner diameter of the upstream piping (the piping connected to the inlet pipe section 12 from the upstream side). Alternatively, the inclination of the inclined pipe section 122 may be set so that the extension line of the pipe axis (central axis) of the first horizontal pipe section 121 passes through the downstream opening 12b of the valve pipe 124 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 valve pipe 124 (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 piping).

[0041] <Valve body and pivot support> 2 to 5, a pivotal support portion 15 is provided on the downstream end of the valve pipe 124, i.e., the inlet pipe portion 12, and the valve element 14 is rotatably held by the pivotal support portion 15. The pivotal support portion 15 may be formed integrally with the valve pipe 124 at the top of the valve pipe 124.

[0042] The valve element 14 mainly has a valve body 141 and a pivot shaft portion 143. The valve body 141 is configured in a substantially disk shape so as to be able to close the downstream opening 12b of the inlet pipe portion 12. A connecting portion 141a that connects to the pivot shaft portion 143 is provided at the top of the valve body 141. A pivotally supported portion 144 that is detachably held by the pivot support portion 15 is provided at both ends of the pivot shaft portion 143.

[0043] In this embodiment, the center of gravity of the valve body 141 is located downstream of the pivot shaft 143, and the connecting portion 141a has a shape that is bent upstream from the valve body 141 toward the pivot shaft 143. The connecting portion 141a serves as a gripped portion for gripping the valve body 14 when replacing the valve body 14. The connecting portion 141a and the gripped portion may be provided separately.

[0044] The opening surface of the downstream opening 12b of the inlet pipe section 12 (valve pipe 124) is substantially vertical, and the valve body 141 blocks the downstream opening 12b substantially perpendicularly along this vertical surface when no drainage is occurring. That is, the angle that the disc shape of the valve body 141 makes with the vertical plane 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, i.e., on the periphery of the downstream opening 12b of the valve pipe 124. 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, diverging from the inner circumferential surface to the end surface of the inlet pipe section 12 (valve pipe 124). That is, the valve seat surface 12c may be a tapered surface (inclined surface). An annular packing 16 capable of tightly contacting the valve seat surface 12c of the inlet pipe section 12 is provided on the outer peripheral surface of the valve body 141. The packing 16 may be, for example, a V-packing. This improves the tightness of the packing 16 against the valve seat surface 12c, and increases the water blocking effect of the valve body 141 when wastewater backflows.

[0045] The pivot shaft portion 143 is composed of, for example, a substantially cylindrical shaft member 145 and a shaft insertion portion 146 having a through hole 146a into which the shaft member 145 is inserted. The supported shaft portions 144 are provided at both ends of the shaft member 145. The shaft member 145 is made of, for example, stainless steel. The shaft insertion portion 146 is formed integrally with the valve body 141 (connection portion 141a). The diameter of the through hole 146a of the shaft insertion portion 146 is larger than the diameter of the shaft member 145. This allows the shaft insertion portion 146 to rotate together with the valve body 141, supported by the shaft member 145. The shaft insertion portion 146 and the supported shaft portion 144 may be spaced apart.

[0046] The supported portion 144 may be, for example, a cylindrical cap member having a hole 144a into which the end of the shaft member 145 is fitted. Specifically, as shown in Fig. 6, the hole 144a of the supported portion 144 may have a tapered shape that narrows toward the back. This makes it easier to press the shaft member 145 into the hole 144a of the supported portion 144 when attaching the supported portion 144 to the shaft member 145, and also makes it harder for the supported portion 144 to come off the shaft member 145. In particular, by suddenly narrowing the hole 144a at the deepest part of the hole 144a, the shaft member 145 is engaged with the supported portion 144, which makes it easier to position and fix the two.

[0047] The support portion 15 is provided with a recess 15a into which the supported portion 144 is inserted. The recess 15a has, for example, a tapered shape that widens toward the upper end, and the portion of the bottom of the recess 15a that abuts against the supported portion 144 has an arc shape that corresponds to the shape of the supported portion 144. As shown in Figure 5, the support portion 15 may have a seat 15b that connects to the valve pipe 124. Furthermore, a protrusion 124a that is used to align the drainage manhole body 11 and the valve element 124 may be provided integrally with the seat 15b at the top of the valve pipe 124.

[0048] In this embodiment, the supported portion 144 remains in the recess 15a of the support portion 15 without any other fixing means. This improves the workability when installing or replacing the valve element 14. Even if the weight of the valve element 14 (e.g., approximately 100 g) causes the supported portion 144 to shift position within the recess 15a of the support portion 15, the supported portion 144 naturally returns to its original position (the bottom of the recess 15a). Furthermore, when no drainage is required, the valve body 141 fits into the valve pipe 124 due to the effect of the packing (V-packing), making it difficult for the supported portion 144 to shift position within the recess 15a. Furthermore, when backflow is prevented, the valve body 141 tightly adheres to the valve seat surface 12c of the inlet pipe 12 (valve pipe 124), further reducing the likelihood of the supported portion 144 shifting position within the recess 15a.

[0049] Furthermore, in this embodiment, the bottom of recess 15a has a curvature that fits cap-shaped supported portion 144, so that supporting portion 15 and supported portion 144 are in surface contact. In contrast, in rotating shaft portion 143 of valve body 14, shaft member 145 on which supported portion 144 is provided and through-hole 146a of shaft insertion portion 146 have different diameters, so that they are in line contact. Therefore, the frictional force between supporting portion 15 and supported portion 144 is greater than the frictional force between shaft member 145 and shaft insertion portion 146, so that shaft insertion portion 146 can rotate together with valve body 141, supported by shaft member 145.

[0050] Furthermore, if the shaft member 145 and the shaft insertion portion 146 (through hole 146a) become stuck together due to, for example, deterioration over time, in other words, if the shaft insertion portion 146 (valve body 141) can no longer rotate with the shaft member 145 as support, the cylindrical shaft support portion 144 will be able to rotate within the recess 15a because the bottom of the recess 15a is arc-shaped.

[0051] In the above description, a cylindrical cap member is used as the supported portion 144, and the portion of the recess 15a that abuts against the supported portion 144 is formed in an arc shape, but instead, the supported portion 144 may be formed in a shape with corners (for example, a rectangular parallelepiped), and the shape of the recess 15 may also be formed to match the supported portion 144. In this case, if the shaft member 145 and the shaft insertion portion 146 are fixed together, the supported portion 144 cannot be rotated within the recess 15a, but because the supported portion 144 is less likely to move within the recess 15a, wear on the supported portion 15, which is difficult to replace, can be suppressed.

[0052] In this embodiment, it is preferable that the hardness of the constituent material of the supported portion 144 is lower than the hardness of the constituent material of the support portion 15. For example, the supported portion 144 may be made of polyethylene resin or a polyethylene-based elastomer, and the support portion 15 may be made of a hard polyvinyl chloride resin. In this way, if the supported portion is made of a softer material than the support portion 15, the supported portion 144 can be more easily removed from the support portion 15, making it easier to replace the valve element 14. In addition, wear on the support portion 15, which is difficult to replace, can be reduced when assembling the supported portion 144 to the support portion 15, when the valve element 14 is operating, when replacing the valve element 14, etc. Furthermore, even if the shaft member 145 and the shaft insertion portion 146 become stuck together and the supported portion 144 rotates within the recess 15a of the supporting portion 15, the self-lubricating properties of plastic are exerted, suppressing wear on the supporting portion 15 and limiting wear on the supported portion 144, thereby enabling the service life of the valve body 14 to be met (for example, 10 years).

[0053] <Operation of backflow prevention mass> When no drainage is occurring, the valve body 141 contacts the valve seat surface 12c of the inlet pipe section 12 and blocks the downstream opening 12b of the inlet pipe section 12. When wastewater flows out of the indoor drainage equipment 2 while the valve body 141 is blocking the downstream opening 12b, the wastewater that flows into the inlet pipe section 12 through the drainage pipe line 1 pushes open the valve body 141, which is in contact with the valve seat surface 12c of the inlet pipe section 12, by water pressure. As a result, the wastewater flows from the inlet pipe section 12 into the drainage manhole body 11, and then flows through the outflow pipe section 13 and out of the backflow prevention manhole 10. Furthermore, because the center of gravity of the valve body 141 is located downstream of the pivot shaft section 143, once the wastewater has flowed out of the inlet pipe section 12, the valve body 141 closes the downstream opening 12b again by its own weight.

[0054] On the other hand, even if the drainage water 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, so the drainage water will not enter the drainage pipe 1 upstream of the valve body 14. Therefore, it is possible to prevent the backflowing drainage water and the air compressed by this drainage water from spraying out of the indoor drainage equipment 2.

[0055] <Replacing the valve body> In this embodiment, the valve disc 14 can be replaced through the inspection port 11a by removing the supported portion 144 of the valve disc 14 from the support portion 15 (recess 15a). At this time, the center of gravity of the valve body 141 is located downstream of the pivot shaft 143 on which the supported portion 144 is provided. In other words, the connecting portion 141a connecting the valve body 141 and the pivot shaft 143 has a shape that is bent upstream from the valve body 141 toward the pivot shaft 143. Therefore, the valve disc 14 can be easily replaced (the old valve disc 14 can be removed and a new valve disc 14 can be attached) while avoiding interference between the packing 16 of the valve disc 14 and the valve pipe 124. Furthermore, as mentioned above, by constructing the supported portion 144 from a softer material than the support portion 15, the supported portion 144 can be more easily removed from the support portion 15, making replacement of the valve body 14 even easier and suppressing wear on the support portion 15, which is difficult to replace. Furthermore, if the backflow prevention mass 10 is buried deep underground and a jig (for example, a magic wand) must be used to replace the valve body 14, the connecting portion 141a (the gripped portion) is gripped with the jig for replacement, and at this time, even if the valve body 14 and the support portion 15 come into contact at a position other than the predetermined position, the support portion 15 is less likely to be damaged.

[0056] <Features of the embodiment> As described above, according to the backflow prevention manhole 10 of this embodiment, the pivotal support portion 15 that rotatably holds the valve element 14 is provided on the valve pipe 124 (the downstream end of the inlet pipe portion 12) that protrudes into the drainage manhole main body 11. In addition, the pivotal support portion 144 that is detachably held on the pivotal support portion 15 is provided at the end of the pivotal shaft portion 143 of the valve element 14. Therefore, the valve element 14 can be easily replaced through the inspection opening 11a by simply removing the pivotal support portion 144 from the pivotal support portion 15. Furthermore, because the valve element 14 can be replaced simply by making the pivotal support portion 144 detachable from the pivotal support portion 15, an increase in manufacturing costs can be suppressed.

[0057] In the backflow prevention mass 10 of this embodiment, the pivot shaft portion 143 of the valve body 14 may include a substantially cylindrical shaft member 145 and a shaft insertion portion 146 into which the shaft member 145 is inserted. The supported portion 144 may be provided at the end of the shaft member 145, and the shaft insertion portion 146 may be formed integrally with the valve body 141 and rotatable using the shaft member 145 as a support. In this configuration, the supported portion 144 does not generally rotate with the shaft member 145, reducing friction between the supported portion 144 and the support portion 15 and suppressing wear on the support portion 15, which is difficult to replace. Furthermore, compared to a configuration in which the supported portion 144 rotates directly on the support portion 15, the diameter of the shaft member 145, which is the shaft supporting the rotation of the valve body 141, can be made smaller, thereby reducing the contact area of ​​the shaft. Therefore, the frictional force between the shaft member 145 and the shaft insertion portion 146 can be reduced, and the valve body 141 can be rotated more easily.

[0058] In the backflow prevention tank 10 of this embodiment, the supported portion 144 may be a cap-shaped member having a hole 144a into which the end of the shaft member 145 is fitted. In this case, the supported portion 144 can be more easily attached to the shaft member 145 than when the supported portion 144 is a donut-shaped member having a through-hole, thereby improving the assembly accuracy of the backflow prevention tank 10.

[0059] In the backflow prevention mass 10 of this embodiment, the supported portion 144 and the shaft insertion portion 146 may be spaced apart. In this way, compared to when the supported portion 144 and the shaft insertion portion 146 abut against each other, it is possible to reduce friction when the shaft insertion portion 146 rotates, and it is also possible to prevent the supported portion 144 from rotating (rotating together) with the shaft insertion portion 146, thereby preventing increased wear between the supported portion 144 and the shaft insertion portion 146.

[0060] In the backflow prevention block 10 of this embodiment, the support portion 15 may be provided with a recess 15a into which the supported portion 144 is inserted. The recess 15a may have a tapered shape that widens toward the upper end, and the portion of the bottom of the recess 15a that abuts against the supported portion 144 may have an arc shape. In this way, the opening side of the recess 15a provided in the support portion 15 is widened, making it easier to assemble and remove the supported portion 144. Furthermore, even if the position of the supported portion 144 shifts from the bottom of the recess 15a (the abutment portion) due to pressure on the valve body 14 when preventing backflow of wastewater, the supported portion 144 will easily return to its original abutment portion.

[0061] In the backflow prevention mass 10 of this embodiment, the valve element 14 may have a gripped portion (connecting portion 141a) for gripping the valve element 14 during replacement. This makes it even easier to remove and attach the supported portion 144 from the support portion 15 during replacement of the valve element 14.

[0062] Furthermore, in the backflow prevention block 10 of this embodiment, the valve body 141 may close the downstream opening 12b of the inlet pipe section 12 substantially vertically when no drainage is occurring. This makes it easier to open and close the valve body 141 when drainage is occurring. Furthermore, compared to when the valve body 141 is tilted when no drainage is occurring, the valve element 14 is less likely to come off when backflow of drainage occurs.

[0063] Furthermore, in the backflow prevention mass 10 of this embodiment, the hardness of the constituent material of the supported portion 144 may be lower than the hardness of the constituent material of the support portion 15. In this way, the supported portion 144 is made of a softer material than the support portion 15, making it easier to remove the supported portion 144 from the support portion 15 and facilitating replacement of the valve element 14. Furthermore, wear on the support portion 15, which is difficult to replace, can be reduced when assembling the supported portion 144 to the support portion 15, when the valve element 14 is operating, when replacing the valve element 14, etc.

[0064] Furthermore, in the backflow prevention tank 10 of this embodiment, the inlet pipe section 12 may have a valve pipe 124 attached to the downstream side from the inside of the drainage tank body 11. A pivot support section 15 may be provided on the downstream end of the valve pipe 124, and the valve element 14 may be configured to be able to close the downstream opening 12b of the valve pipe 124. In this way, the valve pipe 124 that is opened and closed by the valve element 14 is attached from the inside of the drainage tank body 11, so that the valve element 14 can be attached integrally with the valve pipe 124, making it easier to assemble the backflow prevention tank 10.

[0065] In addition, the backflow prevention tank 10 of this embodiment may have the following features.

[0066] In the wastewater inlet pipe section 12 provided on the side wall of the drainage manhole main body 11, the downstream pipe bottom may be located lower than the upstream pipe bottom. In this configuration, the flow rate of the wastewater increases when the wastewater flows from the upstream side to the downstream side of the inlet pipe section 12, making it easier for the valve body 141 of the valve element 14 that blocks the downstream opening 12b of the inlet pipe section 12 to open due to the flow of wastewater. Therefore, even when the amount of wastewater is small, clogging of the backflow prevention manhole 10 by wastewater or the like can be suppressed. This configuration is particularly useful when the flow gradient of the pipe connected from the upstream side to the inlet pipe section 12 is small and the flow rate of the wastewater in that pipe is low.

[0067] The bottom of the drainage manhole body 11 may be located below the bottom of the downstream pipe of the inlet pipe section 12. This prevents waste matter from accumulating downstream of the valve body 141 in the drainage manhole body 11 and obstructing the opening of the valve body 141. This further prevents drainage blockages in the backflow prevention manhole 10 due to waste matter.

[0068] The difference in elevation between the bottom of the downstream side and the bottom of the upstream side of the inflow pipe 12 may be approximately ¼ or more of the inner diameter of the piping connected to the inflow pipe 12 from the upstream side. This sufficiently increases the flow rate of the wastewater as it flows from the upstream side to the downstream side of the inflow pipe 12, making it easier for the valve body 141 to open due to the flow of wastewater. This further reduces the occurrence of wastewater clogging in the backflow prevention basin 10 due to filth and the like.

[0069] The inflow pipe section 12 may include a first horizontal pipe section 121 that is located upstream and has a horizontal or approximately 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.

[0070] 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.

[0071] An extension 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 the inner wall surface of the inclined pipe section 122. This prevents the wastewater from colliding with the apex of the inclined pipe section 122 (the apex of the inner wall of the pipe) as it flows from the upstream side to the downstream side of the inlet pipe section 12, thereby preventing the flow rate of the wastewater from decreasing. This makes it possible to realize a state in which the valve body 141 is easily opened by the flow of wastewater.

[0072] 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 tank 10 can be reduced, making it easier to assemble the backflow prevention tank 10.

[0073] (Variation 1) The difference between the first modification and the above-described embodiment is the structure of the pivot shaft portion 143 and the pivotally supported portion 144 of the valve body 14, as shown in Fig. 7. Note that Fig. 7 shows only one end side of the pivot shaft portion 143. In Fig. 7, the same components as those in the above-described embodiment shown in Figs. 2 to 5 are denoted by the same reference numerals.

[0074] In the first modification, the end 143a of the pivot shaft 143 is thinner than the other portions, and the end 143a is rotatably inserted into a through-hole of the donut-shaped pivotally supported portion 144. That is, in the first modification, the pivot shaft 143 is configured to be rotatable together with the valve body 141, with the pivotally supported portion 144 as a support.

[0075] The supported portion 144 is placed in a semi-fixed state in the recess 15a of the support portion 15. In other words, a clearance is provided between the supported portion 144 and the recess 15a. The supported portion 144 may receive the torque of rotation of the pivot shaft portion 143 (end 143a) and rotate at a slower speed than the pivot shaft portion 143. The end 143a of the pivot shaft portion 143 may be provided with a stopper 147 to prevent the supported portion 144 from falling off.

[0076] The same effects as those of the above-described embodiment can be obtained in Modification 1. That is, the valve element 14 can be easily replaced through the inspection opening 11a simply by removing the supported portion 144 from the support portion 15. Furthermore, because the valve element 14 can be replaced simply by making the supported portion 144 detachable from the support portion 15, an increase in manufacturing costs can be suppressed.

[0077] In addition, even in the first modification, it is preferable that the hardness of the constituent material of the supported portion 144 is lower than the hardness of the constituent material of the support portion 15. For example, the supported portion 144 may be made of polyethylene resin or a polyethylene-based elastomer, and the support portion 15 may be made of a hard polyvinyl chloride resin. Constructing the supported portion from a material softer than the support portion 15 makes it easier to remove the supported portion 144 from the support portion 15, facilitating replacement of the valve element 14. Furthermore, wear of the support portion 15, which is difficult to replace, can be reduced during assembly of the supported portion 144 to the support portion 15, during operation of the valve element 14, and replacement of the valve element 14. Furthermore, even when the supported portion 144 rotates within the recess 15a of the support portion 15, the self-lubricating properties of plastic are exhibited, thereby reducing wear of the support portion 15 and limiting wear of the supported portion 144, thereby achieving the intended service life of the valve element 14 (e.g., 10 years).

[0078] (Variation 2) The difference between the second modification and the above embodiment is that, as shown in Figure 8, the inlet pipe section 12 is configured without using a valve pipe 124, in other words, the downstream side of the inlet pipe section 12 (second horizontal pipe section 123) is inserted into the inside of the drainage manhole main body 11. In Figure 8, the same components as those in the above embodiment shown in Figure 2 are denoted by the same reference numerals.

[0079] In the second modification, the second horizontal pipe section 123 is inserted from the outside to the inside of the drainage manhole body 11 through the opening 11b in the side wall of the drainage manhole body 11, thereby connecting the drainage manhole body 11 and the inflow pipe section 12. 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. The downstream opening 12b of the inflow pipe section 12 (second horizontal pipe section 123) is located closer to the interior of the drainage manhole body 11 than the opening 11b of the drainage manhole body 11. A valve seat surface 12c that can abut against the valve body 141 is provided on the end face of the second horizontal pipe section 123. When the second horizontal pipe section 123 is inserted into the opening 11b, the protrusion 123a of the second horizontal pipe section 123 abuts against the side wall (cylindrical section 11c) around the opening 11b of the drainage manhole body 11, thereby positioning the second horizontal pipe section 123 in the insertion direction.

[0080] An extension portion 111 may be provided above the opening 11b on the inner wall of the drainage manhole body 11, extending toward the interior of the drainage manhole body 11 along the outer periphery of the second horizontal pipe portion 123. The pivotal support portion 15 may be fixed onto the extension portion 111 by a method such as adhesive bonding, screwing, or welding. The rotating shaft portion 143 pivotally supported by the pivotal support portion 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 manhole body 11.

[0081] According to the second modification, the downstream side of the inflow pipe section 12 is inserted into the inside of the drainage manhole main body 11, so that the configuration of the inflow pipe section 12 is simplified and the backflow prevention manhole 11 is easy to assemble.

[0082] (Other embodiments) In the above embodiment (including modified examples, the same applies below), a backflow prevention mass 10 is provided in a drainage pipeline 1 configured in series. However, this is not limited to this, and a 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.

[0083] 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.

[0084] In the above embodiment, the inflow pipe section 12 is composed of the first horizontal pipe section 121, the inclined pipe section 122, the second horizontal pipe section 123, and the valve pipe 124. However, the configuration of the inflow pipe section 12 is not particularly limited. For example, the first horizontal pipe section and / or the second horizontal pipe section 123 do not have to be provided. Alternatively, a third horizontal pipe section may be provided midway along the inclined pipe section 122.

[0085] In addition, in the above embodiment, the inlet pipe section 12 and the drainage manhole main body 11 are separate bodies, but instead, the inlet pipe section 12 and the drainage manhole main body 11, excluding the valve pipe 124, may be integrally molded.

[0086] Furthermore, in the above embodiment, the pivotal support part 15 and the valve pipe 124 are integrally formed, but instead, the pivotal support part 15 may be removably fixed to the valve pipe 124 with screws or the like. By making the pivotal support part 15 removable, it becomes possible to replace the pivotal support part 15 in the unlikely event that it is damaged.

[0087] Although the embodiments have been described above, it will be understood that various modifications 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 the present disclosure is not impaired. Furthermore, the terms "first," "second," etc., described above, are used to distinguish the terms to which these terms are attached, and do not limit the number or order of the terms. [Explanation of symbols]

[0088] 1 Drainage line 2 Indoor drainage equipment 3A, 3B, 3C drainage mass 10 Backflow prevention tank 11 Drainage manhole body 11a Inspection hatch 11b opening 11c Cylindrical part 11d Inverter 111 Extension section 12 Inflow pipe section 12a Upstream opening 12b Downstream opening 12c Valve seat surface 121 1st horizontal pipe section 121a Steps 122 Inclined pipe section 123 2nd horizontal pipe section 123a Protrusion 124 Valve pipe 124a Convex part 13 Outlet pipe section 13a Step 14 Valve body 141 Valve body 141a Connection 143 Rotating shaft 144 Axial branch 144a Hole 145 Shaft member 146 Shaft insertion part 146a Through hole 147 Stopper 15 axis branches 15a Recess 15b Pedestal 16 Packing

Claims

1. A backflow prevention basin is installed in a drainage pipe connecting an indoor drainage system and a sewer pipe to prevent drainage water flowing backward through the drainage pipe from entering the upstream side. The drainage basin body, An inspection port opening at the top of the 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 valve body configured to be able to close a downstream opening of the inlet pipe portion; Equipped with At least a downstream end of the inlet pipe portion protrudes into the inside of the drainage basin body, a bearing portion is provided on the downstream end of the inlet pipe portion, and the valve body is rotatably held on the bearing portion; The valve body is A valve body; a pivot shaft portion provided on the valve body; a supported portion provided at an end of the rotation shaft portion and detachably held by the support portion; and By removing the supported portion from the support portion, the valve body can be replaced through the inspection port. Backflow prevention mass.

2. The rotation shaft portion is A substantially cylindrical shaft member; a shaft insertion portion into which the shaft member is inserted; and The supported portion is provided at an end of the shaft member, The shaft insertion portion is formed integrally with the valve body and is rotatable with the shaft member as a support. The backflow prevention mass according to claim 1.

3. The supported portion is a cap-shaped member having a hole into which the end of the shaft member is fitted. The backflow prevention mass according to claim 2.

4. The supported portion and the shaft insertion portion are spaced apart. The backflow prevention mass according to claim 2 or 3.

5. The support portion is provided with a recess into which the supported portion is inserted, The recess has a tapered shape that widens toward the upper end, and a portion of the bottom of the recess that abuts against the supported portion has an arc shape. The backflow prevention mass according to any one of claims 1 to 4.

6. The valve body has a gripping portion for gripping the valve body during replacement. The backflow prevention mass according to any one of claims 1 to 5.

7. The valve body closes the downstream opening of the inlet pipe section vertically when no drainage is required. The backflow prevention mass according to any one of claims 1 to 6.

8. the hardness of the constituent material of the supported portion is lower than the hardness of the constituent material of the supporting portion; The backflow prevention mass according to any one of claims 1 to 7.

9. The inlet pipe section has a valve pipe attached to the downstream side from the inside of the drainage basin body, The support portion is provided on the downstream end of the valve pipe, The valve body is configured to be able to close a downstream opening of the valve pipe. The backflow prevention mass according to any one of claims 1 to 8.

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