Backflow prevention fittings and their drainage pipe systems

Abstract

To provide a reverse flow suppressing joint mountable to a vertically standing drain piping in building foundations, allowing easy inside inspection and maintenance like sweeping, and a drain piping system having the reverse flow suppressing joint.MEANS FOR SOLVING THE PROBLEM: There is provided a reverse flow suppressing joint which has a joint body having an inflow port, an outflow port and an inspection port arranged between the inflow port and the outflow port, a lid part detachably mounted to the inspection port, a valve seat part provided inside the joint body, and a valve element rotatably provided at an upper part of the valve seat part, wherein an outflow port center axis is arranged orthogonal to a center axis of the inflow port. A drain piping system which has the reverse flow suppressing joint is also provided.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a backflow prevention fitting and a drainage pipe system that can be attached to a drainage pipe with a vertically rising portion in a building foundation, etc., and in particular to a backflow prevention fitting and a drainage pipe system that can be easily attached to even a drainage pipe with a vertically rising portion by arranging the central axis of the outlet perpendicular to the central axis of the inlet. [Background technology]

[0002] Generally, wastewater discharged from drainage facilities such as toilets, bathrooms, and kitchens in homes is collected in a drainage manhole installed within the residential area via drainage pipes connected to each drainage facility, and the collected wastewater is then discharged into the main sewer pipe via a public manhole or manhole.

[0003] In addition, in order to prevent backflow water generated in downstream drainage equipment such as the sewer main pipe from entering the home, backflow prevention devices have been developed that are attached to drainage manholes, etc., as described in Patent Publication No. 2020-153508 (Patent Document 1), and backflow prevention valves that are attached to the middle or end of drainage pipes, etc., as described in Patent Publication No. 2021-169701 (Patent Document 2) and Patent Publication No. 2002-294780 (Patent Document 3).

[0004] On the other hand, due to the recent frequent occurrence of abnormal weather caused by global warming, etc., there have been many cases where large amounts of rainwater flow into the main sewer pipes in a short period of time, and there is an increasing need to install backflow prevention devices not only in catch basins, etc., but also in the upstream drainage pipes inside homes, etc. In addition, since the diameter of the drainage pipes inside homes is usually smaller than that of downstream drainage pipes, they are prone to clogging with sludge and debris, and so it is also necessary to address this problem.

[0005] For this reason, drain traps (backflow prevention devices) equipped with inspection ports have been developed, as described in, for example, JP 2010-275763 A (Patent Document 4), so that backflow prevention devices attached to drainage pipes inside homes can be inspected, cleaned, and otherwise maintained. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2020-153508 [Patent Document 2] Patent Publication No. 2021-169701 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-294780 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-275763 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the backflow prevention devices described in Patent Documents 1 to 4 above are horizontal backflow prevention devices that are intended to be installed horizontally (placed horizontally) on drainage pipes, etc. that are arranged approximately horizontally. For this reason, there has been a problem in that the backflow prevention devices described in Patent Documents 1 to 4 cannot be installed on drainage pipes that have a vertically rising portion in, for example, a building foundation, unless a horizontal portion is provided in the drainage path by connecting a catch basin or a 90° elbow (see Figures 2 and 4 of Patent Document 2 and Figure 3 of Patent Document 3).

[0008] Furthermore, although the drain trap described in Patent Document 4 is provided with an inspection hatch for maintenance, the internal structure is extremely complex, as the valve body is supported by a mounting seat provided inside the drain trap, and so in practice there was a problem that even if the cap member (inspection lid) was removed, it was not possible to easily inspect or clean the inside of the drain trap.

[0009] Therefore, the present invention aims to provide a backflow prevention fitting that can be attached to a drainage pipe having a vertically rising portion in a building foundation, etc., without connecting a drainage manhole or 90° elbow, and that allows easy maintenance such as internal inspection and cleaning, and a drainage pipe system equipped with such a backflow prevention fitting. [Means for solving the problem]

[0010] The inventors of the present invention have conducted extensive research into the layout characteristics of drainage pipes with vertically rising portions in building foundations, etc., and the internal structure of backflow prevention joints, etc. As a result, they have discovered that the above-mentioned problems can be solved if a check valve and its valve seat can be installed inside a joint that is provided with an inspection hatch and is arranged so that the central axis of the outlet and the central axis of the inlet are perpendicular to each other, and have thus completed the present invention.

[0011] Furthermore, it was found that when a check valve is installed inside a joint where the central axis of the outlet and the central axis of the inlet are perpendicular to each other, there is usually a part in the trajectory of the check valve that interferes with the inside of the joint, making it impossible for the check valve to rotate sufficiently. Therefore, it was found that the above problem can be effectively solved by widening the interfering part inside the joint and forming the inspection hatch so that it bulges outward from the joint body, and this has further improved the completeness of the present invention.

[0012] That is, according to the present invention, a backflow prevention fitting is provided which comprises a fitting body having an inlet, an outlet, and an inspection hatch arranged between the inlet and the outlet, a lid portion which can be attached and detached to the inspection hatch, a valve seat portion provided inside the fitting body, and a valve body which is arranged rotatably above the valve seat portion, wherein the central axis of the outlet is arranged perpendicular to the central axis of the inlet.

[0013] Therefore, because the backflow prevention fitting of the present invention has an outlet that is arranged vertically, it can be easily attached to a drainage pipe that has a vertically rising portion in a building foundation, etc., without connecting a catch basin or 90° elbow. In addition, because the backflow prevention fitting of the present invention is equipped with a valve seat inside the fitting and a valve body that is rotatably supported on the valve seat, there is no need to provide a horizontal portion in the drainage path as is the case when installing a conventional horizontal backflow prevention device.

[0014] In this specification, "vertical" does not only mean the vertical direction in the strict sense, but also includes a direction in which wastewater can fall straight down. Furthermore, in this specification, "horizontal" does not only mean the horizontal direction in the strict sense, but also includes a small gradient generally required to flow wastewater sideways.

[0015] In the backflow prevention fitting of the present invention, it is preferable that the central axis of the inspection hatch be arranged parallel to the central axis of the outflow outlet, and it is even more preferable that the central axis of the inspection hatch be arranged offset (eccentric) from the central axis of the outflow outlet in a direction away from the inflow inlet.

[0016] By arranging the central axis of the inspection hatch parallel to the central axis of the outflow port, the inspection hatch is positioned facing upward, facilitating maintenance such as inspection and cleaning of the inside of the joint, and effectively preventing backflow water from overflowing from the inspection hatch.

[0017] Also, by offsetting (eccentrically positioning) the central axis of the inspection hatch from the central axis of the outflow port, the rotation range of the valve element suspended inside the fitting is expanded, so that under normal circumstances the valve element can be kept fully open by its own weight, preventing clogging of the backflow prevention fitting with sludge, debris, etc. Furthermore, the inspection hatch can be formed to bulge outward from the fitting body, making it easier to access the inside of the fitting through the enlarged inspection hatch.

[0018] In the backflow prevention joint of the present invention, it is preferable that the joint body has a curved pipe portion that communicates with the inlet and is curved downward, and the valve seat portion is formed at the end of the curved pipe portion.

[0019] By providing a curved pipe section inside the fitting body, not only can the wastewater flowing into the fitting from the inlet be smoothly deflected downward, but the shape of the valve body can also be simplified to an approximately circular shape to match the shape of the valve seat.

[0020] In the backflow prevention joint of the present invention, the valve body may be rotatably supported on the lid portion.

[0021] If the valve disc is attached to the cover of the inspection hatch, the valve disc can be removed by removing the cover, leaving the inside of the joint essentially hollow with no walls or other parts that form irregularities. This makes it easy to inspect and clean the inside of the joint, even in a small space.

[0022] In the backflow prevention joint of the present invention, it is preferable that the lid portion be composed of a lid portion main body for opening and closing the inspection hatch and a cap portion for supporting the valve body, and it is more preferable that the lid portion main body be rotatable circumferentially relative to the cap portion.

[0023] When the lid portion is composed of a lid portion main body and a cap portion as described above, in order to make it easy to set the valve body in the specified position, it is preferable to provide a first fitting portion on the inner surface of the inspection hatch that supports the cap portion from below so that it cannot rotate circumferentially, and to provide a second fitting portion on the cap portion that fits into the first fitting portion.

[0024] If the locking means for the lid portion is a bayonet mechanism, not only can the lid portion be easily prevented from coming off the inspection hatch by coordinating the lid portion main body with the inspection hatch, but the second fitting portion of the cap portion can be clamped between the lid portion main body and the first fitting portion of the inspection hatch without causing any rattling or rotation, so that the valve body supported by the cap portion can be set accurately in the specified position and can be accurately abutted against the valve seat portion.

[0025] Furthermore, if the valve is attached to the lid, if the lid becomes detached from the inspection hatch for some reason, the valve will also come off, making it impossible to prevent backflow. For this reason, the backflow prevention fitting of the present invention preferably has a locking mechanism to prevent the lid from becoming detached from the inspection hatch due to an increase in water or air pressure inside the fitting. In this case, the locking mechanism can be, for example, a bayonet mechanism that prevents the lid from becoming detached from the inspection hatch by rotating the lid body in the circumferential direction relative to the inspection hatch.

[0026] In the present invention, in a drainage pipe system having a first drainage pipe that opens sideways and extends approximately horizontally indoors or from indoors to outdoors, and a second drainage pipe that opens upward and rises vertically underground or from a building foundation, the above-mentioned backflow prevention joint of the present invention can be placed between the first drainage pipe and the second drainage pipe and connected to the first drainage pipe and the second drainage pipe.

[0027] Therefore, according to the present invention, even in a drainage pipe having a vertically rising portion, it is possible to construct a drainage pipe system that has a backflow prevention function in the rising portion, and it is possible to reduce the number of piping parts such as drain manholes and 90° elbows. [Effects of the Invention]

[0028] The backflow prevention fitting of the present invention comprises a fitting body having an inlet, an outlet, and an inspection hatch arranged between the inlet and the outlet, a lid portion that can be attached and detached to the inspection hatch, a valve seat portion provided inside the fitting body, and a valve body that is arranged rotatably above the valve seat portion, in which the central axis of the outlet is arranged perpendicular to the central axis of the inlet.

[0029] Therefore, according to the present invention, the backflow prevention joint can be easily attached to a drainage pipe that has a vertically rising portion in a building foundation, etc., and since the joint is equipped with a valve seat and a valve body that is rotatably supported on the valve seat, there is no need to provide a horizontal portion in the drainage path as is the case when installing a conventional horizontal backflow prevention device.

[0030] In the backflow prevention joint of the present invention, the central axis of the inspection hatch may be arranged parallel to the central axis of the outflow outlet, or the central axis of the inspection hatch may be arranged offset (eccentric) from the central axis of the outflow outlet in a direction away from the inflow inlet.

[0031] Therefore, according to the present invention, the inspection hatch is positioned facing upward, facilitating maintenance such as inspection and cleaning of the inside of the fitting, and effectively preventing backflow water from overflowing from the inspection hatch. Furthermore, the rotation range of the valve body suspended inside the fitting is expanded, preventing clogging of the backflow prevention fitting with sludge, debris, etc. Furthermore, the inspection hatch can be formed to bulge outward from the fitting body, making it easier to access the inside of the fitting through the expanded inspection hatch.

[0032] In the backflow prevention joint of the present invention, the joint body may have a curved pipe portion that communicates with the inlet and is curved downward, and the valve seat portion may be formed at the end of the curved pipe portion.

[0033] Therefore, according to the present invention, not only can the wastewater flowing into the fitting from the inlet be smoothly deflected downward, but the shape of the valve body can also be simplified to an approximately circular shape to match the shape of the valve seat portion.

[0034] The backflow prevention joint of the present invention can provide a backflow prevention joint in which the valve body is rotatably supported on the lid portion.

[0035] Therefore, according to the present invention, when the lid is removed, the valve body is also removed, and after the valve body is removed, the inside of the fitting can be made essentially hollow with no other parts that form walls or unevenness, making it easy to inspect and clean the inside of the fitting even in a small space. [Brief explanation of the drawings]

[0036] [Figure 1] 1 is a perspective view showing the entire backflow prevention joint according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a side view of the backflow prevention coupling shown in FIG. 1. [Figure 3] FIG. 2 is a front view of the backflow prevention coupling shown in FIG. 1. [Figure 4] FIG. 2 is a plan view of the backflow prevention joint shown in FIG. 1. [Figure 5] 5 is a cross-sectional view of the backflow prevention joint shown in FIG. 4 taken along the line AA. [Figure 6] 1 is a perspective view showing the entire cover and valve body of a backflow prevention joint according to a first embodiment of the present invention. FIG. [Figure 7] FIG. 7 is a front view of the lid and valve body shown in FIG. 6. [Figure 8] FIG. 7 is a side view of the lid and valve body shown in FIG. 6. [Figure 9] FIG. 7 is an exploded view of the lid and valve body shown in FIG. 6. [Figure 10] FIG. 10 is a perspective view showing the entire cover and valve body of a backflow prevention joint according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a front view of the lid and valve body shown in FIG. [Figure 12] FIG. 11 is a side view of the lid and valve body shown in FIG. [Figure 13] 1 is a cross-sectional view showing a state in which the backflow prevention joint according to the first embodiment is connected to a drainage pipe that stands vertically outside the foundation of a building. [Figure 14] 1 is a partial cross-sectional view showing a backflow prevention joint according to a first embodiment connected to a drainage pipe standing vertically within a building foundation. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0037] A backflow prevention joint according to one embodiment of the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the following examples, and various modifications are possible within the scope of the technical concept of the present invention.

[0038] [First embodiment] <Fitting body> Fig. 1 shows a perspective view illustrating the entire backflow prevention fitting 1 according to a first embodiment of the present invention. Fig. 2 shows a side view of the backflow prevention fitting 1 shown in Fig. 1, Fig. 3 shows a front view of the backflow prevention fitting 1 shown in Fig. 1, and Fig. 4 shows a plan view of the backflow prevention fitting 1 shown in Fig. 1. Fig. 5 shows a cross-sectional view of the backflow prevention fitting 1 shown in Fig. 4 taken along the line AA.

[0039] 1 to 4 and 5, the backflow prevention fitting 1 of the first embodiment is mainly composed of a substantially cylindrical fitting body 2, a lid portion 3, and a valve body 4 (see FIG. 5) attached to the lid portion 3. The fitting body 2 has an inlet 20, an outlet 21, a curved pipe portion 22 communicating with the inlet 20, and an inspection hatch 23 that opens upward, all of which are integrally formed. Although polyvinyl chloride resin is used as the material for the fitting body 2, there are no particular restrictions on the material that can be used, and known materials such as plastics can be used.

[0040] As can be seen with reference to Figure 5, the inlet 20 and outlet 21 of the fitting body 2 have a socket shape, and therefore, stepped portions 200, 210 that function as stoppers when the tip of the connected drain pipe abuts against them are formed inside the inlet 20 and outlet 21. Also, in this embodiment, the inlet 20 and outlet 21 have a socket shape, but the inlet 20 and / or outlet 21 may also have a spigot shape (not shown).

[0041] The inspection hatch 23 of the fitting body 2 has a trunk 230 that rises upward and has approximately the same width as the curved pipe portion 22. The trunk 230 is formed on the fitting body 2 so as to bulge in the direction away from the inlet 20. A cylindrical receiving portion 231 is formed at the top of the trunk 230, and the receiving portion 231 has a step 232 formed therein for detachably supporting the lid portion 3. Therefore, even if the diameter of the receiving portion 231 differs from the diameter of the curved pipe portion 22, the diameter of the receiving portion 231 is increased or decreased at the boundary between the receiving portion 231 and the trunk 230, ensuring the opening diameter of the inspection hatch 23 (receiving portion 231) required for inspecting the interior of the backflow prevention fitting 1, regardless of the diameter of the curved pipe portion 22. The inner peripheral surface of the inspection hatch 23 is formed with a recess 233 as a first fitting portion for supporting the lid portion 3 from below so that it cannot rotate circumferentially (see FIGS. 1 to 3).

[0042] In this embodiment, the curved pipe portion 22 is formed so as to protrude downward into the interior of the fitting body 2 from the inlet 20 provided in the common side wall of the fitting body 2 and the barrel portion 230 (see FIG. 5). A valve seat 24 is formed at the outlet end of the curved pipe portion 22, against which the valve disc 3 abuts, and which functions to cooperate with the valve disc 3 to prevent the flow of backflowing water. A step 240 connected to the inner wall surface of the fitting body 2 is formed at the bottom of the valve seat 24, and the valve seat 24 is arranged so as to form a substantially circular abutment surface with the outlet end of the curved pipe portion 22, including the step 240.

[0043] For this reason, in this embodiment, when the outlet 21 of the backflow prevention fitting 1 is connected to a drain pipe having a vertically rising portion (see Figures 13 and 14), the end of the outlet of the curved pipe portion 22 is used to form a valve seat portion 24 inside the fitting body 2, which is inclined from downstream to upstream as it moves from top to bottom. Furthermore, when the valve seat portion 24 is inclined as described above, the valve element 4, which is normally hanging down due to its own weight, forms a gap with the valve seat portion 24, ensuring a smooth flow of forward flow drainage, and only in abnormal times (when the water level rises) will the valve element 4 come into contact with the valve seat portion 24, thereby effectively preventing backflow water.

[0044] Furthermore, within the fitting body 2, a downwardly curved ceiling portion 25 is formed in the upper half of the curved pipe portion 22, which not only enables the wastewater flowing into the fitting body 2 from the inlet 20 to be smoothly deflected downward, but also allows the shape of the valve body 4 to be simplified to an approximately circular shape to match the shape of the valve seat portion 24.

[0045] In this embodiment, the ceiling portion 25 is integrally formed as part of the curved pipe portion 22, but it may also be configured as a separate, independent part separate from the curved pipe portion 22, or the curved pipe portion 22 itself may be configured as a separate, independent part separate from the fitting body 2.

[0046] Also, the ceiling portion 25 may be supported by the cover portion 3, and the valve element 4 may be rotatably supported on the upper end (valve seat portion 24) of the ceiling portion 25. Furthermore, although not shown, in this embodiment, it is not necessarily necessary to provide the curved pipe portion 22 or the ceiling portion 25 inside the joint body 2, and the valve seat portion (for example, a step portion) may be provided directly on the inner peripheral surface of the joint body 2 by matching the shape of the valve element to the shape of the valve seat portion.

[0047] In the backflow prevention fitting 1 of this embodiment, the central axis b of the outlet 21 is arranged perpendicular to the central axis a of the inlet 20. Therefore, if the outlet 21 of the fitting body 2 is connected to a drain pipe having a vertically rising portion, the inlet 20 will be arranged horizontally, and therefore can be easily connected to a drain pipe 5 arranged approximately horizontally (see Figures 13 and 14).

[0048] In this embodiment, the central axis c of inspection hatch 23 is arranged parallel to the central axis b of outlet 21, and furthermore, in this embodiment, it is arranged offset (eccentric) from the central axis b of outlet 21 in a direction away from inlet 20 (see Figures 13 and 14). For this reason, inspection hatch 23 is arranged facing upward, and unlike conventional horizontal backflow prevention devices, wastewater inside the fitting does not easily overflow even when cover 3 is opened, and the inside of backflow prevention fitting 1 can be easily inspected by removing cover 3.

[0049] In addition, in this embodiment, by arranging the central axis c of the inspection hatch 23 so that it is offset (eccentric) from the central axis b of the outlet 21, the rotation range of the valve element 4 suspended inside the fitting body 2 is expanded, so that under normal circumstances the valve element 4 can be ensured to be sufficiently open due to its own weight, preventing clogging of the backflow prevention fitting 1 with sludge, debris, etc. Furthermore, because the inspection hatch 23 can be formed so that it bulges outward from the fitting body 2, access to the inside of the fitting body 2 through the enlarged inspection hatch 23 is easier.

[0050] <Lid> Fig. 6 shows a perspective view illustrating the entire cover 3 and valve element 4 of the backflow prevention coupling 1 according to the first embodiment of the present invention. Fig. 7 shows a front view of the cover 3 and valve element 4 shown in Fig. 6, Fig. 8 shows a side view of the cover 3 and valve element 4 shown in Fig. 6, and Fig. 9 shows an exploded view of the cover 3 and valve element 4 shown in Fig. 6. Note that Figs. 6 to 9 show the valve element 4 intentionally tilted to facilitate understanding, but in reality, when no load is applied, the valve element 4 is suspended in a substantially vertical direction due to its own weight.

[0051] As shown in Figures 5 and 6 to 9, the cover 3 has a thick, generally disk-like shape, and the valve element 4 is rotatably supported on its underside via a support arm 32 extending downward. In addition, a pair of protrusions 300 are formed on the top surface of the cover 3 for gripping and rotating the cover 3. Both the cover 3 and the valve element 4 are made of vinyl chloride resin, but there are no particular limitations on the material used, and known materials such as plastics can be used.

[0052] More specifically, as shown in Figure 9, the lid portion 3 has a convex portion 300 formed on its upper surface, and is composed of a lid portion main body 30 for opening and closing the inspection hatch 23, a cap 31 that is fitted into the lower part of the lid portion main body 30, and a support arm 32 that is integrally molded with the cap 31 and extends downward from the underside of the cap 31.

[0053] Furthermore, a cylindrical ring 311 is provided on the upper surface of the cap 31 to make it easier to grip the cap 31, and a pair of legs 310 are provided on the periphery of the lower surface of the cap 31 as second fittings arranged in opposing positions and can fit into the recessed first fitting portion 233 provided on the inner peripheral surface of the inspection hatch 23. That is, in this embodiment, the lid body 30 and the cap 31 are configured as separate and independent parts, and the lid body 30 is rotatable in the circumferential direction relative to the cap 31.

[0054] Furthermore, a groove 301 is formed on the side surface (circumferential surface) of the lid body 30, and a packing 33 made of an elastomer material is fitted into the groove 301 to improve the sealing performance with the inspection hatch 23 (see Figure 5). In this embodiment, the lid 3 is composed of the lid body 30 and the cap 31 with the support arm 32 as separate independent parts, but it may also be formed as an integrated part.

[0055] In the backflow prevention fitting 1 of this embodiment, when closing the inspection hatch 23, first, the pair of legs 310 of the cap 31 are fitted into a pair of recesses 233 provided inside the inspection hatch 23. By fitting the legs 310 into the recesses 233, the cap 31 supporting the valve disc 4 is supported from below by the fitting of the recesses 233 and is set so that it cannot rotate circumferentially. After setting the cap 31 inside the inspection hatch 23, the lid body 30 is further placed on the step 232 of the receiving portion 231 of the inspection hatch 23. This sandwiches the cap 31 between the lid body 30 and the recess 233 of the inspection hatch without causing any rattle or rotation, so that the valve disc 4 supported by the cap 31 is set accurately in the predetermined position and can be accurately abutted against the valve seat 24.

[0056] When opening the inspection hatch 23, the valve disc 4 can be easily removed by removing the lid body 30 and cap 31 from the inspection hatch 23 in the reverse order of the above. If the lid body 30 and cap 31 are formed integrally, the valve disc 4 can be removed together with the lid 3 by removing it from the inspection hatch 23.

[0057] 1, 2, 4, and 6, the backflow prevention fitting 1 of this embodiment is equipped with a locking means 7 for preventing the lid 3 from accidentally detaching from the inspection hatch 23 due to an increase in water or air pressure inside the fitting 1. In this embodiment, the locking means 7 is preferably a bayonet mechanism that prevents the lid 3 from detaching from the inspection hatch by rotating the lid main body 30 in the circumferential direction relative to the inspection hatch 23. More specifically, the locking means 7 is composed of a pair of crank-shaped protrusions 70 provided at opposing positions 180° apart on the side surface (circumferential surface) of the lid main body 30 of the lid 3, and a pair of crank-shaped cutouts 71 provided at opposing positions 180° apart on the receiving portion 231 of the inspection hatch 23.

[0058] Therefore, after the cap 31 supporting the valve disc 4 is set inside the inspection hatch 23 and the cover body 30 is fitted into the receiving portion 231 of the inspection hatch 23, the cap 31 is easily locked without rotating by rotating it to a position where the protrusion 70 and the notch 71 engage, preventing the cap 31 from accidentally coming off the inspection hatch 23 while holding it down to prevent rattling. In the bayonet mechanism described above, the notch 71 does not have to be a crank-shaped protrusion and can simply be a rod-shaped protrusion. Furthermore, the locking means 7 does not necessarily have to be a bayonet mechanism; known engaging means such as a hook that engages the cover 3 from above can also be used, particularly when the cover body 30 and cap 31 are integrally formed.

[0059] <Valve body> 5 to 8, in this embodiment, the valve element 4 has a flat disk shape and is rotatably supported by the support arm 32 of the cover part 3. The valve element 4 is rotatably disposed at a position where it contacts the upper part of the end of the curved pipe part 22 (ceiling part 25) provided inside the joint body 2, i.e., at a position where it contacts the upper part of the valve seat part 24.

[0060] Although not shown, a stopper may be provided at the fulcrum of the valve disc 4 to normally hold the valve disc 4 in a position where it is suspended vertically (FIG. 5) or in a position tilted from the vertical toward the valve seat 24, and to restrict at least the valve disc 4 from rotating in a direction away from the valve seat 24. Furthermore, in order to normally hold the valve disc 4 in a position tilted from the vertical toward the valve seat 24, a protrusion such as a support rod that abuts against the surface of the valve disc 4 may be provided inside the fitting body 2.

[0061] As described above, if a stopper is provided at the fulcrum of the valve disc 4, in the event of an abnormality (when the water level rises), the valve disc cannot rotate from the vertical direction in a direction away from the valve seat 24, making it possible to reliably rotate the valve disc 4 toward the valve seat 24 against backflow water rising from the bottom up. Also, if the valve disc is held in a position tilted from the vertical direction toward the valve seat 24 by the fulcrum stopper or a protrusion inside the fitting body 2, backflow water rising from the bottom up will collide diagonally with the tilted valve disc 4, making it possible to reliably rotate the valve disc 4 toward the valve seat 24 in this case as well.

[0062] [Second embodiment] <Valve body> In the backflow prevention joint 1a according to the second embodiment of the present invention, the configuration of the joint body and lid portion other than the valve body 4a and the effects thereby achieved are all the same as the configuration of the joint body 2 and lid portion 3 of the backflow prevention joint 1 according to the first embodiment described above and the effects thereby achieved, so a detailed description will be omitted here. Therefore, the reference numerals in the drawings relating to the joint body 2 and lid portion 3 of the backflow prevention joint 1a are the same as the reference numerals in the drawings relating to the backflow prevention joint 1.

[0063] Figure 10 shows a perspective view of the entire cover 3 and valve element 4a of a backflow prevention coupling 1a according to a second embodiment of the present invention. Figure 11 shows a front view of the cover 3 and valve element 4a shown in Figure 10, and Figure 12 shows a side view of the cover 3 and valve element 4a shown in Figure 10. Note that, for ease of understanding, Figures 10 to 12 show the valve element 4a intentionally tilted, but in reality, when no load is applied, the valve element 4a is suspended in a substantially vertical direction due to its own weight.

[0064] In this embodiment, the valve body 4a (check valve) is provided with a rotation trigger means 8a that rotates the valve body 4a toward the valve seat portion 24 when backflow water rises inside the backflow prevention joint 1, so that the valve body 4a can close reliably even against the backflow water flow that is unique to vertically arranged backflow prevention joints, where backflow water rises from bottom to top.

[0065] In this embodiment, the rotation trigger means 8a is configured as an inclined portion 80a formed in the lower region of the valve body 4a by bending the flat, disk-shaped valve body 4a midway into a "L" shape in a side view (FIG. 12). More specifically, the inclined portion 80a is configured as an inclined surface that is normally inclined from a vertical plane passing through the rotation axis (fulcrum 40a) of the valve body 4a toward the valve seat 24 as it moves away from the rotation axis (fulcrum 40a) of the valve body 4a.

[0066] Furthermore, the inclined portion 80a may be fixedly connected to or integrally formed with the portion of the valve body 4a other than the inclined portion 80a (the upper region of the valve body 4a) so as to maintain the entire valve body 4a in a constant "L-shaped" form, or may be connected to the portion other than the inclined portion 80a so as to be bendable (rotatable) relative to the portion other than the inclined portion 80a. When the valve body 4a is made bendable as described above, the movable range of the inclined portion 80a relative to the portion other than the inclined portion 80a is set so that the inclined portion 80a can be bent from a 180° open state (see, for example, FIG. 8) so as to form the same plane as the upper region of the valve body 4a, to a constant bending angle in which the valve body 4a is bent in a "L-shaped" state (FIG. 12), and it is preferable to restrict the inclined portion 80a so as not to bend to an angle smaller than the constant bending angle.

[0067] Furthermore, if the valve element 4a is bendable in a dogleg shape as described above, when the valve element 4a abuts against the valve seat 24, the valve element 4a becomes a flat disk shape like the valve element 4 of the first embodiment, and therefore the shape of the valve seat 24 can also be made approximately circular to match the outer contour of the valve element 4a. On the other hand, if the valve element 4a is fixed in a dogleg shape, the shape of the valve seat 24 must also be bent in a dogleg shape to match the outer contour of the dogleg-shaped valve element 4a.

[0068] In this embodiment, the inclined portion 80a does not necessarily have to be an inclined plane, but may be, for example, an inclined surface (not shown) formed in the lower region of the valve body 4a that bulges conically from the downstream side to the upstream side, as long as it is formed so as to incline from a vertical plane passing through the rotation axis (fulcrum 40a) of the valve body 4a toward the valve seat portion 24 as it moves away from the rotation axis (fulcrum 40a) of the valve body 4a under normal conditions.

[0069] In this embodiment, as described above, the valve body 4a is provided with an inclined portion 80a as a rotation trigger means 8a for the valve body 4a. Therefore, even if backflow prevention fitting 1 is connected to a vertically standing pipe and backflow water rises from bottom to top within fitting body 2, the backflow water will collide diagonally with inclined portion 80a, thereby reliably generating a force that rotates valve body 4a toward valve seat portion 24, thereby preventing malfunction of the backflow prevention valve (valve body 4a).

[0070] Also, although not shown, in this embodiment, the rotation trigger means 8a can be configured as a buoyancy generating part with a specific gravity smaller than that of water attached to the valve body 4, 4a, and under normal conditions, the buoyancy generating part can be positioned closer to the valve seat portion 24 than the vertical plane passing through the rotation axis (fulcrum 40, 40a) of the valve body 4, 4a.

[0071] If the buoyancy generating section is positioned eccentrically toward the valve seat section from the vertical plane passing through the rotation axis (fulcrum 40, 40a) of the valve body 4, 4a as described above, the backflow water rising from bottom to top can rotate the valve body 4, 4a toward the valve seat section 24, thereby raising the buoyancy generating section in a pulling-up manner.

[0072] [Example of installation of backflow prevention fitting] Figure 13 shows a cross-sectional view of a drainage pipe system 10 according to one embodiment of the present invention, in which the backflow prevention fitting 1 according to the first embodiment is connected to a drainage pipe 6 that rises vertically outside the building foundation 11 and a drainage pipe 5 that is arranged horizontally within the building foundation 11. Figure 14 shows a partial cross-sectional view of a drainage pipe system 10a according to another embodiment of the present invention, in which the backflow prevention fitting 1 according to the first embodiment is connected to a drainage pipe 6a that passes through the building foundation 11a and rises vertically within the foundation 11a and a drainage pipe 5a that is arranged horizontally within the building foundation 11a. Note that even if the backflow prevention fitting 1 according to the first embodiment is replaced with the backflow prevention fitting 1a according to the second embodiment in Figures 13 and 14, the connection manner and effects are the same as when the backflow prevention fitting 1 according to the first embodiment is used, so detailed description thereof will be omitted here.

[0073] As shown in Figure 13, in the drainage pipe system 10 of this embodiment, the downstream drainage pipe 6 rises vertically from the ground 90 outside the building foundation 9 made of concrete. Although not shown, the downstream drainage pipe 6 is usually collected in a drainage inlet within the residential area and connected to the sewer main via a public inlet or manhole. Meanwhile, within the building foundation 9, the upstream drainage pipe 5 is arranged approximately horizontally. Although not shown, the upstream drainage pipe 5 is usually connected to drainage facilities within the building, such as toilets, bathrooms, and kitchens.

[0074] In this embodiment, the backflow prevention fitting 1 is arranged so that the central axis b of the outlet 21 is perpendicular to the central axis a of the inlet 20 (see Figure 5), so by positioning the backflow prevention fitting 1 so that the inspection hatch 23 faces upward, the outlet 21 of the fitting body 2 can be easily connected to the downstream drain pipe 6 and the inlet 20 to the upstream drain pipe 5.

[0075] As shown in Figure 14, in the drainage pipe system 10a of this embodiment, a sleeve-shaped bent pipe (sheath pipe) 60a, bent at approximately 90° and piercing a concrete building foundation 9a, is embedded in the foundation 9a. Also, within the sleeve-shaped bent pipe 60a, the drainage pipes constituting the downstream drainage pipe 6a are arranged, from the downstream side, as follows: a first inlet socket 61a; a flexible pipe 62a that can be connected to the first inlet socket 61a and is bent approximately 90° along the sleeve-shaped bent pipe 60a; a second inlet socket 61a connected to the flexible pipe 62a; and a short straight pipe 63a that is connected to the second inlet socket 61a and forms a vertically extending spigot. Although not shown, the downstream drainage pipe 6a is typically collected in a drainage inlet within the residential area and connected to a sewer main via a public inlet or manhole.

[0076] Furthermore, the upstream drain pipe 5a is arranged substantially horizontally within the building foundation 9a. Although not shown, the upstream drain pipe 5a is usually connected to drainage facilities such as toilets, bathrooms, and kitchens within the building.

[0077] In this embodiment, the backflow prevention fitting 1 is arranged so that the central axis b of the outlet 21 is perpendicular to the central axis a of the inlet 20 (see Figure 5), so by positioning the backflow prevention fitting 1 so that the inspection hatch 23 faces upward, the outlet 21 of the fitting body 2 can be easily connected to the downstream drain pipe 6a and the inlet 20 to the upstream drain pipe 5a.

[0078] As described above, the backflow prevention joint 1 of this embodiment can be easily attached to drainage pipes 6, 6a that have a rising portion that rises vertically in a building foundation 9, 9a, etc., without connecting a catch basin or 90° elbow. Furthermore, the backflow prevention joint 1 of this embodiment is equipped with a valve seat 24 inside the joint body 2 and a valve element 4 that is pivotally supported on the valve seat 24, so there is no need to provide a horizontal portion in the drainage path as is the case when installing a conventional horizontal backflow prevention device.

[0079] In addition, in the backflow prevention fitting 1 of this embodiment, the valve seat portion 24 is formed at an angle using the end of the curved pipe portion 22 provided inside the fitting body 2, so that even if the outlet 21 is connected to a vertically standing drain pipe 6, 6a, under normal circumstances the valve body 4 (check valve) will be in an open state (suspended state) due to its own weight, and in the event of an abnormality, the valve body 4 (check valve) can be operated to reliably close due to the rise and collision of backflow water.

[0080] Furthermore, in the backflow prevention fitting 1 of this embodiment, the valve element 4 is attached to the cap portion 31 of the lid portion 3, so that if the cap portion 31 is removed, the valve element 4 is also removed, and if the valve element 4 is attached to the lid portion 3 in which the lid portion main body 30 and cap 31 are integrally formed, the valve element 4 is also removed if the lid portion 3 is removed. For this reason, in this embodiment, after the valve element 4 is removed, the inside of the backflow prevention fitting 1 is essentially hollow, with no other parts forming walls or unevenness, so that maintenance such as inspection and cleaning of the backflow prevention fitting 1 can be easily performed even in a small space. [Explanation of symbols]

[0081] 1,1a···Backflow prevention joint 10,10a···Drainage pipe system 2. Fitting body 20...Inlet 200...Stepped section 21... Outlet 210...Stepped section 22 Flow path section 23 Inspection hatch 230 Torso 231 Receiving part 232...Stepped section 233 First fitting portion (recess) 24 Valve seat 240...Stepped section 25 Ceiling 3...Lid part 30 Lid body 300···Convex part 301 Groove 31····Cap 310 Second fitting portion (leg portion) 311 Cylindrical ring 32 Support arm 33... Packing 4, 4a... Valve body 40, 40a Fulcrum 5, 5a...Upstream drain pipe 6, 6a...Downstream drain pipe 60a···· Sleeve bent pipe (sheath pipe) 61a···· Socket 62a...Flexible tube 63a...Straight pipe 7. Locking means 70...Protrusion 71 Notch 8a... Rotation trigger means 80a...Slope part 9,9a...Building foundation 90...ground a,b,c...center axis

Claims

1. a fitting body having an inlet, an outlet, and an inspection port disposed between the inlet and the outlet; A lid portion that is detachably attached to the inspection hatch; a valve seat portion provided inside the joint body; and a valve body rotatably disposed above the valve seat, the joint body has a curved pipe portion that is in communication with the inlet and curved downward, The valve seat portion is formed at an end of the curved pipe portion, A backflow prevention joint, characterized in that the central axis of the outlet is arranged perpendicular to the central axis of the inlet.

2. 2. The backflow prevention joint according to claim 1, wherein the central axis of the inspection hatch is arranged parallel to the central axis of the outflow port.

3. 3. The backflow prevention joint according to claim 2, wherein the central axis of the inspection hatch is offset from the central axis of the outflow outlet in a direction away from the inflow inlet.

4. 2. The backflow prevention joint according to claim 1, wherein the valve body is rotatably supported by the lid portion.

5. The lid portion is composed of a lid portion main body for opening and closing the inspection hatch and a cap portion for supporting the valve body, and The backflow prevention joint according to claim 4, wherein the lid body is rotatable in a circumferential direction relative to the cap portion.

6. a first fitting portion is provided on an inner peripheral surface of the inspection hatch, the first fitting portion supporting the cap portion from below so as to prevent the cap portion from rotating in a circumferential direction; and 6. The backflow prevention joint according to claim 5, wherein the cap portion is provided with a second fitting portion that fits into the first fitting portion.

7. A backflow prevention joint as described in claim 6, characterized in that it is provided with a locking means for preventing the lid portion from coming off the inspection hatch due to an increase in water or air pressure within the joint body.

8. A backflow prevention joint as described in claim 7, characterized in that the locking means is a bayonet mechanism that prevents the lid from coming off the inspection hatch by rotating the lid body circumferentially relative to the inspection hatch.

9. a first drain pipe that opens laterally and extends substantially horizontally inside the building or from the building to the outside; a second drain pipe that opens upward and rises vertically from the ground or building foundation; and a backflow prevention joint according to any one of claims 1 to 6, which is disposed between the first drain pipe and the second drain pipe and connected to the first drain pipe and the second drain pipe; A drainage pipe system comprising:

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