JP7841989B2 - Backflow prevention joint - Google Patents

Description

This invention relates to a backflow prevention joint for connecting a horizontally extending drain pipe and a vertically extending drain pipe, comprising an internal valve pipe and a check valve (valve body) that opens and closes relative to the valve pipe. More particularly, the invention relates to a backflow prevention joint characterized in that the check valve (valve body) is rotatably supported at a position above the valve pipe and offset toward the inlet side from the opening end of the valve pipe.

Generally, wastewater discharged from drainage systems in homes, such as toilets, bathrooms, and kitchens, is collected in drainage pits installed on the property via drainage pipes connected to each drainage system. The wastewater collected in these pits then flows into the main sewer system via public manholes or other access points.

Furthermore, to prevent backflow water generated in downstream drainage facilities such as main sewer lines from entering homes, backflow prevention devices that are installed at the inlet of drainage manholes, etc., are widely known, as described in, for example, Japanese Patent Publication No. 2020-153508 (Patent Document 1).

On the other hand, in recent years, due to the occurrence of extreme weather events associated with global warming, there have been many cases where large amounts of rainwater flow into the main sewer pipes in a short period of time. Therefore, in order to more effectively prevent backflow of rainwater, for example, as described in Japanese Patent Publication No. 2021-169701 (Patent Document 2), drainage pits or vertical pipes are installed between the upstream and downstream drainage pipes with a difference in elevation, and backflow prevention devices, such as those described in Patent Document 1, are being installed at the outlet of the upstream drainage pipe.

Japanese Patent Publication No. 2020-153508 Japanese Patent Publication No. 2021-169701

However, depending on the amount of backflow water generated (such as rainwater), it may flow horizontally, directly impacting the check valve of the backflow prevention device, or it may flow upward from below the check valve, causing the liquid level to rise. Therefore, in the check valves (valve bodies) described in Patent Documents 1 and 2, which are suspended almost directly below (vertically) the pivot point, the valve body moves in either the opening or closing direction depending on how the backflow water impacts it, resulting in extremely unstable opening and closing operation.

In particular, when a backflow prevention device is connected between an upstream drain pipe and a downstream drain pipe with a difference in elevation, the backflow water does not flow horizontally, colliding with the front of the check valve, but rather flows upward from below the check valve. Therefore, with check valves (valve bodies) like those described in Patent Documents 1 and 2, the backflow water flows around to the back side (upstream side) of the valve body before the front side (downstream side), preventing the valve body from opening and blocking the flow of backflow water.

Furthermore, attempting to install a backflow prevention device, such as the one described in Patent Document 1, at the connection point between an upstream drainage pipe and a downstream drainage pipe with a difference in elevation necessitates the installation of a drainage manhole or vertical pipe for mounting the backflow prevention device at that location. This results in a complex configuration and a large-scale construction project.

Furthermore, when attempting to install a backflow prevention device, such as the one described in Patent Document 1, by providing drainage manholes or vertical pipes, there is a problem in that the drainage manholes or vertical pipes must be made larger than the size determined by the drainage flow rate in order to secure space for the movement of the check valve. Moreover, since backflow prevention devices are generally installed near the walls of drainage manholes or vertical pipes, even if inspection openings are provided at the top, they cannot be easily accessed (see Figure 2 in Patent Document 2), causing problems with maintenance.

Therefore, the present invention aims to provide a backflow suppression joint (backflow prevention device) that can reliably close the check valve (valve body) against backflow water that flows in horizontally, directly impacting the check valve (valve body), and against backflow water that flows in upward from below the check valve, causing the liquid level to rise. Furthermore, the invention aims to provide a backflow suppression joint (backflow prevention device) that can be easily installed between upstream and downstream drain pipes with a difference in elevation, without the need for drain manholes or vertical pipes, and that can reliably close the check valve (valve body) against backflow water that flows upward from below the check valve (valve body).

The inventors of this invention have diligently studied the piping layout and the structure of the check valve (valve body) when installing a backflow prevention joint (backflow prevention device) at the connection point between an upstream drain pipe and a downstream drain pipe. As a result, they discovered that in a joint having an inlet open for connection to the upstream drain pipe and an outlet open for connection to the downstream drain pipe, if a valve pipe communicating with the inlet and a check valve (valve body) that opens and closes relative to the valve pipe are provided inside, and the check valve (valve body) is rotatably supported at a position above the valve pipe and offset towards the inlet side from the opening end of the valve pipe, it is possible to ensure sufficient space for the check valve (valve body) to move while reliably closing the check valve (valve body) against backflowing water, without unnecessarily increasing the size of the backflow prevention joint. This led to the completion of the present invention.

In other words, the present invention provides a backflow suppression joint comprising an inlet, an outlet, a body connecting the inlet and outlet, a valve tube communicating with the inlet and protruding into the body, a valve seat formed at the open end of the valve tube which slopes toward the inlet from top to bottom, and a valve body rotatably supported at the upper part of the valve tube and offset toward the inlet side from the open end of the valve tube. In this case, the inlet and outlet may extend horizontally, or the inlet may extend horizontally and the outlet may extend vertically.

In this invention, since the pivot point of the valve body is positioned above the valve tube and offset toward the inlet side compared to the opening end (valve seat) of the valve tube, the trajectory of the lower end of the valve body—that is, the trajectory of the part of the valve body furthest from the pivot point—approaches the inlet and valve seat. Therefore, without changing the opening and closing angle of the valve body, the range of motion of the valve body in the outlet region of the valve tube can be substantially narrowed, allowing for a more compact backflow prevention joint.

Furthermore, since the center of gravity of the valve body is located vertically below the pivot point of the valve body, if the pivot point of the valve body is positioned offset as described above, when the valve body is suspended, it will be positioned at an inclination such that the contact surface with the valve seat approaches the inlet side from top to bottom. Therefore, it is preferable that the center of gravity of the valve body be positioned downstream of the contact surface with the valve seat when the valve body is suspended.

In other words, in this invention, when the outer diameter of the open end of the valve tube is D (mm) and the distance from the open end face of the valve tube to the pivot point of the valve body is L (mm), it is desirable that L/D be 0.15 or more and 0.45 or less, and more preferably 0.20 or more and 0.40 or less.

If the L/D ratio is less than 0.15, the valve body cannot be sufficiently tilted so that the backflow water rising upward from the outlet first strikes the downstream surface of the valve body. This makes the valve body more likely to move in the opening direction, and thus insufficient to block the flow of backflow water. Furthermore, it becomes impossible to narrow the range of motion of the valve body in the outlet region of the valve pipe to the extent that it contributes to the compactness of the backflow suppression joint. On the other hand, if the L/D ratio is greater than 0.45, space must be provided for the movement of the support arm of the elongated valve body, resulting in the disadvantage of the joint body becoming unnecessarily large.

Furthermore, the valve body preferably has a circular shape so that it can make liquid-tight contact with the circular valve seat when viewed from the front. It is also preferable that, when viewed from the side, it has a recess that extends from the downstream side to the upstream side, such that the force (resistance) received from reverse flow drainage is greater, and the force (resistance) received from forward flow drainage is smaller.

As a result, the backflow prevention joint of the present invention can reliably close the valve body even when backflow water flows in horizontally, directly impacting the valve body, or when backflow water flows in upward from below the valve body, causing the liquid level to rise. Furthermore, even when the backflow prevention joint of the present invention is installed between an upstream drain pipe and a downstream drain pipe with a height difference, the backflow water rising upward from the outlet of the backflow prevention joint will impact the downstream surface of the valve body first, rather than the upstream surface, thus making the valve body closing more reliable.

In this invention, the inlet may be formed to have a first central axis extending horizontally, and the outlet may be formed to have a second central axis extending vertically. That is, the backflow suppression joint of this invention can be configured to include an inlet having a first central axis extending horizontally, an outlet having a second central axis extending vertically, a body connecting the inlet and outlet, a valve tube communicating with the inlet and protruding into the body, a valve seat formed at the open end of the valve tube which slopes towards the inlet from top to bottom, and a valve body rotatably supported at the upper part of the valve tube and at a position offset towards the inlet from the open end of the valve tube.

In this case, the backflow prevention joint of the present invention can be easily installed between an upstream drain pipe and a downstream drain pipe with a difference in elevation. Because of the elevation difference, it can more effectively prevent backflow and the rise of backflow water than conventional backflow prevention devices installed between upstream and downstream drain pipes at approximately the same level. Furthermore, in this invention, since the pivot point of the valve body is offset, a narrowed movable space for the valve body is secured in the outlet region of the valve pipe, allowing the valve body to operate reliably to close against backflow water.

In this specification, "horizontal" does not refer only to the strictly horizontal direction, but also includes a range that includes the degree of gradient required when draining water horizontally. Similarly, "vertical" does not refer only to the strictly vertical direction, but also includes a range that includes the degree of error that occurs during the manufacturing and installation of joints.

In this invention, a valve pipe is provided that communicates with the inlet and protrudes into the body of the joint, so as to ensure that wastewater flowing horizontally from the inlet is reliably and smoothly deflected downwards, even when the outlet is positioned perpendicular to the inlet. The valve pipe only needs to be provided so that all or part of its circumferential length protrudes into the body of the joint.

Furthermore, the valve body maintains a slightly open position under normal conditions, allowing for forward flow of drainage even when the drainage volume is low. This prevents drainage blockage caused by foreign objects. Therefore, the opening end of the valve pipe is sloped from top to bottom, approaching the inlet.

As described above, when the backflow prevention joint of the present invention is provided with an inlet opening horizontally and an outlet opening vertically, it can be easily connected directly or via an elbow pipe or the like between an upstream drain pipe and a downstream drain pipe with a difference in elevation. Furthermore, since the backflow prevention joint of the present invention includes a valve body that functions as a check valve and a valve seat portion of a valve pipe, connecting it between an upstream drain pipe and a downstream drain pipe simultaneously provides the function of a backflow prevention device.

Furthermore, if the backflow suppression joint has an inlet and outlet arranged perpendicularly to each other, it is preferable to further include an inspection port having a third central axis extending from the body and moving upward diagonally away from the inlet, and a cover portion that is detachably attached to the inspection port, with the valve body being rotatably supported by the cover portion.

Furthermore, if the backflow prevention joint of the present invention is equipped with an inspection port that extends diagonally upward from the body of the joint and away from the inlet, it is possible to secure the movable space of the check valve without unnecessarily increasing the size of the backflow prevention joint. Additionally, since the valve body and valve seat can be easily accessed through the inspection port, maintenance can be easily performed.

Furthermore, by attaching the valve body to the cover, removing the cover also removes the valve body, effectively creating a hollow space inside the joint after the valve body is removed. This makes maintenance, such as inspection and cleaning of the joint's interior, much easier.

In this invention, the lid is preferably composed of a cap portion that is non-rotatably mounted to the inspection opening in the circumferential direction, and a lid body that is rotatably mounted to the inspection opening in the circumferential direction on top of the cap portion, with the valve body supported by the cap portion.

Furthermore, when the lid is composed of a lid body and a cap portion as described above, it is preferable that a first engaging portion is provided on the inner circumferential surface of the inspection opening to fix the cap portion so that it cannot rotate circumferentially relative to the inspection opening, and that a second engaging portion is provided on the cap portion to engage with the first engaging portion, so that the valve body can be easily set in the predetermined position.

Furthermore, if the valve body is attached to the cover, and the cover detaches from the inspection port for any reason, the valve body will also detach, making it impossible to prevent backflow of drainage. Therefore, in this invention, it is preferable to have a locking mechanism to prevent the cover from detaching from the inspection port due to an increase in water or air pressure inside the joint. The locking mechanism can be, for example, a bayonet mechanism that allows for arbitrary selection of engagement and disengagement between the cover and the inspection port by rotating the cover circumferentially relative to the inspection port.

Furthermore, using a bayonet mechanism as a locking mechanism for the lid not only prevents unintended detachment of the lid, but also allows the cap to be securely fixed by being sandwiched between the lid body and the inspection opening. This ensures that the valve body supported by the cap is precisely set in its designated position without any looseness.

In this invention, to prevent the joint body from becoming unnecessarily large and to ensure sufficient space for valve movement downstream of the valve body, it is preferable that the diameter of the inspection port be the same as the diameter of the outlet. Furthermore, while the diameter of the outlet may be the same as the diameter of the inlet, it is preferable that it be larger than the diameter of the inlet. Therefore, when the diameter of the outlet is the same as the diameter of the inspection port, the diameter of the inspection port will also be larger than the diameter of the inlet.

Furthermore, in this specification, "identical" bore diameter does not only mean that the bore diameters are exactly the same, but also includes a range where the inner diameter of one bore diameter is approximately the same as the outer diameter of the other bore diameter, or vice versa, including manufacturing tolerances.

According to the present invention, a backflow prevention joint is provided, comprising an inlet, an outlet, a body connecting the inlet and outlet, a valve tube communicating with the inlet and protruding into the body, a valve seat formed at the open end of the valve tube which slopes toward the inlet from top to bottom, and a valve body rotatably supported at the upper part of the valve tube and offset toward the inlet side from the open end of the valve tube. In this case, the inlet and outlet may extend horizontally, or the inlet may extend horizontally and the outlet may extend vertically.

In particular, in this invention, when the outer diameter of the opening end of the valve tube is D (mm) and the distance from the opening end face of the valve tube to the pivot point of the valve body is L (mm), it is desirable that L/D be 0.15 or more and 0.45 or less, and more preferably 0.20 or more and 0.40 or less. Furthermore, it is preferable that the center of gravity of the valve body is located downstream of the contact surface that abuts the valve seat portion of the valve body when the valve body is suspended.

According to the backflow suppression joint of the present invention, since the pivot point of the valve body is positioned above the valve pipe and offset toward the inlet side than the opening end (valve seat) of the valve pipe, the trajectory of the lower end of the valve body, i.e., the trajectory of the part of the valve body furthest from the pivot point, approaches the inlet and valve seat. Therefore, without changing the opening and closing angle of the valve body, the range of motion of the valve body in the outlet region of the valve pipe can be substantially narrowed, allowing for a more compact backflow suppression joint.

Furthermore, since the center of gravity of the valve body is located vertically below the fulcrum of the valve body, if the fulcrum of the valve body is positioned offset as described above, when the valve body is suspended, it will be positioned at an inclination such that the contact surface with the valve seat approaches the inlet side from top to bottom. Therefore, in this invention, the valve body can be reliably closed not only by backflow water flowing horizontally and directly into the valve body, but also by backflow water flowing upward from below the valve body, causing the liquid level to rise. Moreover, even when the backflow prevention joint of this invention is installed between an upstream drain pipe and a downstream drain pipe with a height difference, backflow water rising upward from the outlet of the backflow prevention joint will hit the downstream surface of the valve body first, rather than the upstream surface, thus making the valve body closing more reliable.

In the backflow prevention joint of the present invention, when an inlet opening horizontally and an outlet opening vertically are provided, it can be easily connected directly or via an elbow pipe or the like between an upstream drain pipe and a downstream drain pipe with a difference in elevation. Furthermore, since the backflow prevention joint of the present invention includes a valve body that functions as a check valve and a valve seat portion of a valve pipe, connecting it between an upstream drain pipe and a downstream drain pipe simultaneously provides the function of a backflow prevention device.

Thus, the backflow prevention joint of the present invention can be easily installed between upstream and downstream drain pipes that have a difference in elevation. Because of this elevation difference, it can more effectively prevent backflow and the rise of backflow water compared to conventional backflow prevention devices installed between upstream and downstream drain pipes that are at approximately the same elevation. Furthermore, in this invention, the pivot point of the valve body is offset, ensuring a narrowed movable space for the valve body in the outlet region of the valve pipe, while still allowing the valve body to reliably close to the backflow water.

Furthermore, in a backflow prevention joint with an inlet and outlet arranged perpendicularly to each other, providing an inspection port extending diagonally upward from the body of the joint and away from the inlet allows for securing the movable space of the check valve without unnecessarily increasing the size of the backflow prevention joint. Additionally, the valve body and valve seat can be easily accessed through the inspection port, facilitating maintenance.

This is a perspective view of a backflow prevention joint according to one embodiment of the present invention, as seen from the inspection port side. Figure 1 is a perspective view of the backflow prevention joint shown from the inlet side. Figures 1 and 2 are side views of the backflow suppression joint. Figures 1 and 2 are front views of the backflow suppression joint. Figures 1 and 2 are rear views of the backflow suppression joint. Figures 1 and 2 are plan views of the backflow prevention joint. Figure 6 is a cross-sectional view of the backflow suppression joint shown, taken along section A-A. Figure 7a is a cross-sectional view of another application example of the backflow suppression joint shown. Figure 7a is a cross-sectional view of another application example of the backflow suppression joint shown. Figure 7a is a cross-sectional view of another application example of the backflow suppression joint shown. This is a perspective view from above of the cover and valve body of a backflow suppression joint according to the first embodiment of the present invention. Figure 8 is a perspective view of the lid and valve body from below. Figures 8 and 9 are front views of the lid and valve body. Figures 8 and 9 are side views of the lid and valve body. Figures 8 and 9 are exploded views of the lid and valve body.

The following describes in detail a backflow suppression joint according to one embodiment of the present invention, with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and various modifications are possible without departing from the technical spirit of the invention.

Figure 1 shows a perspective view of the backflow prevention joint 1 according to one embodiment of the present invention, viewed from the inspection port 7 side. Figure 2 shows a perspective view of the backflow prevention joint 1 shown in Figure 1, viewed from the inlet 2 side. Figure 3 shows a side view of the backflow prevention joint 1 shown in Figure 1. Figure 4 shows a front view of the backflow prevention joint 1 shown in Figure 1. Figure 5 shows a rear view of the backflow prevention joint 1 shown in Figure 1. Figure 6 shows a plan view of the backflow prevention joint 1 shown in Figure 1. Figure 7a shows a cross-sectional view of the backflow prevention joint 1 shown in Figure 6, taken along section A-A.

As shown in Figures 1-6 and 7a, the backflow suppression joint 1 of this embodiment comprises a joint body 10 consisting of an inlet 2, an outlet 3, a body 4 connecting the inlet 2 and the outlet 3, and an inspection port 7 provided in the body 4, and a cover 8 that is detachably attached to the inspection port 7. Furthermore, a valve pipe 5 is provided in the body 4, communicating with the inlet 2 and protruding into the interior of the body 4. A valve seat 50 is formed at the open end of the valve pipe 5, and a valve body 6 is supported within the body 4 so as to be openable and closable relative to the valve seat 50. The backflow suppression joint 1 according to one embodiment of the present invention will be described in detail below, divided into the joint body 10, the cover 8, and the valve body 6.

<Fitting body>
In this embodiment, the joint body 10 includes an inlet 2 that opens horizontally and has a first central axis a extending horizontally, and an outlet 3 that opens vertically and has a second central axis b extending vertically. In this embodiment, the inlet 2 has a socket shape, and the outlet 3 has a spigot shape. Therefore, a socket step portion 20 is formed inside the inlet 2, which functions as a stopper when the tip of the connected drain pipe abuts against it. In this embodiment, the inlet 2 has a socket shape and the outlet 3 has a spigot shape, but the shapes of the inlet 2 and outlet 3 are not limited to this combination, and both may have a socket shape or a spigot shape. Although not shown in the figures, in this embodiment, the joint body may also include an inlet that opens horizontally and extends horizontally, and an outlet that opens vertically and extends vertically.

As described above, the backflow prevention joint 1 of this embodiment has an inlet 2 that opens horizontally and an outlet 3 that opens vertically, so it can be easily connected between an upstream drain pipe and a downstream drain pipe (not shown) that have a difference in elevation. For example, if the upstream drain pipe extends horizontally and the downstream drain pipe extends vertically, the backflow prevention joint 1 can be directly connected between them. If both the upstream and downstream drain pipes extend horizontally while having a difference in elevation, the backflow prevention joint 1 can be connected between them by attaching an elbow pipe or the like to the outlet 3.

Furthermore, since the backflow prevention joint 1 of this embodiment can be easily installed between an upstream drain pipe and a downstream drain pipe with a difference in elevation, it can more effectively prevent backflow and the rise of backflow water compared to conventional backflow prevention devices installed between upstream and downstream drain pipes at approximately the same level, due to the difference in elevation.

In this embodiment, the inspection port 7 has a third central axis c that extends diagonally upward so as it moves away from the inlet 2, and extends diagonally upward from the body portion 4 to form an opening. The upper part of the inspection port 7 has a receiving port shape and a stepped portion 70 is formed for detachably supporting the lid portion 8, which will be described later. Furthermore, the inner circumferential surface of the inspection port 7 is provided with a concave first engaging portion 71 for supporting the lid portion 8 from below and fixing it so that it cannot rotate in the circumferential direction (see Figures 2, 3, and 5).

As described above, in this embodiment, the inspection port 7 is positioned diagonally upwards. Therefore, unlike conventional horizontal backflow prevention devices, the drainage inside the joint does not easily overflow even when the cover 8 is opened. Furthermore, since the inside of the joint body 10 can be easily accessed by removing the cover 8, maintenance can be easily performed. In addition, the inspection port 7 can be effectively utilized as the movable area of the valve body 6 (described later), thus securing the movable space for the valve body 6 without unnecessarily increasing the size of the backflow prevention joint 1.

Therefore, in this embodiment, it is preferable that the diameter of the inspection port 7 is the same as the original diameter of the outlet 3. In particular, by making the diameter of the inspection port 7 the same as the original diameter of the outlet 3, a movable space for the valve body 6 can be formed on the downstream side (opening side) of the valve body 6 using the inspection port 7. This eliminates the need to provide extra space for the movement of the valve body 6, resulting in an efficient size where the width of the outlet 3 and the width of the joint body 10 are approximately the same. Note that "original diameter" refers to the diameter of the inlet 2 and outlet 3 before any adapters or other devices for adjusting their diameters are attached to the receiving or spigot ports.

On the other hand, while the original diameter of outlet 3 may be the same as the original diameter of inlet 2, typically the diameters of the upstream and downstream drain pipes are either the same or the downstream drain pipe has a larger diameter than the upstream drain pipe. Therefore, by using an adapter to adjust the diameter, the original diameter of outlet 3 can be made larger than the original diameter of inlet 2, thereby expanding the application range of the backflow prevention joint 1. Furthermore, as mentioned above, when the original diameter of outlet 3 is the same as the diameter of inspection port 7, the diameter of inspection port 7 will also be larger than the diameter of inlet 2.

Figure 7a shows a cross-sectional view of a backflow suppression joint 1 in which a first reducing increaser 30 is attached only to the outlet 3 to reduce its diameter to the same as the diameter of the inlet 2. Figure 7b shows a cross-sectional view of a backflow suppression joint 1 as a first application example of the backflow suppression joint 1 shown in Figure 7a, in which a reducing socket 21 is attached to the inlet 2 to reduce its diameter, and a second reducing increaser 31 is attached to the outlet 3 to adjust (reduce) its diameter to the same as the reduced diameter of the inlet 2.

As shown in Figures 7a and 7b, in this embodiment, the original diameter of the outlet 3 of the backflow prevention joint 1 is larger than the original diameter of the inlet 2. Therefore, when installing the backflow prevention joint 1 of this embodiment between an upstream drain pipe (not shown) with a horizontal opening and the same diameter at its downstream end as the original diameter of the inlet 2, and a downstream drain pipe (not shown) with a vertical opening at its upstream end, the inlet 2 can be connected directly to the upstream drain pipe, and only the outlet 3 can be fitted with a first reducing insert 30 to adjust (reduce) its original diameter to match the diameter of the downstream drain pipe, in other words, the original diameter of the inlet 2, before connecting the downstream drain pipe (Figure 7a). Furthermore, if the outlet 3 can be connected directly to the downstream drain pipe, the first reducing insert 30 is not necessary.

Furthermore, in the case of the upstream drain pipe (not shown) and downstream drain pipe (not shown) with the same layout as in Figure 7a, if the diameter of either drain pipe is smaller than the original diameter of the inlet 2 and the original diameter of the outlet 3, then a reducing socket 21 should be attached to the inlet 2 to adjust (reduce the diameter) its original diameter to match the diameter of the upstream drain pipe and connected to the upstream drain pipe. Similarly, a second reducing increaser 31 should be attached to the outlet 3 to adjust (reduce the diameter) its original diameter to match the diameter of the downstream drain pipe, in other words, the diameter of the inlet 2 reduced by the reducing socket 21, and connected to the downstream drain pipe (Figure 7b). If the outlet 3 can be connected directly to the downstream drain pipe, then the second reducing increaser 31 is not necessary.

Figure 7c shows a cross-sectional view of a backflow suppression joint 1 as a third application example of the backflow suppression joint 1 shown in Figure 7a, in which a first reducing 45° elbow 32 is attached only to the outlet 3 to reduce its diameter and change the direction of outflow. Figure 7d shows a cross-sectional view of a backflow suppression joint 1 as a fourth application example of the backflow suppression joint shown in Figure 7a, in which a reducing socket 21 is attached to the inlet 2 to reduce its diameter, and a second reducing 45° elbow 33 is attached to the outlet 3 to reduce its diameter and change the direction of outflow.

When installing the backflow prevention joint 1 of this embodiment between an upstream drain pipe (not shown) whose downstream end diameter is the same as the original diameter of the inlet 2 and which opens horizontally, and a downstream drain pipe (not shown) whose upstream end opens diagonally upward, the inlet 2 is connected directly to the upstream drain pipe, and only the outlet 3 is fitted with a first reducing-diameter 45° elbow 32 to reduce its original diameter and change the direction of outflow, and then the downstream drain pipe is connected (Figure 7c).

Furthermore, in the case of the upstream drain pipe (not shown) and downstream drain pipe (not shown) with the same layout as in Figure 7c, if the diameter of either drain pipe is smaller than the original diameter of the inlet 2 and the original diameter of the outlet 3, then a reducing socket 21 is attached to the inlet 2 to adjust (reduce the diameter) its original diameter to match the diameter of the upstream drain pipe, and the upstream drain pipe is connected. A second reducing 45° elbow 33 is attached to the outlet 3 to adjust (reduce the diameter) its original diameter to match the diameter of the downstream drain pipe, in other words, the diameter of the inlet 2 reduced by the reducing socket 21, and to change the direction of outflow, and the downstream drain pipe is connected (Figure 7d).

As can be understood by referring to Figures 7a to 7d, the backflow prevention joint 1 of this embodiment can be easily installed between upstream and downstream drain pipes that have different heights and various diameters and inclinations. This is achieved by attaching a reducing socket 21 or the like that matches the diameter of the upstream drain pipe to the inlet 2 as needed, and by attaching reducing increases 30, 31 or reducing elbows 32, 33 or the like that that match the diameter and inclination of the downstream drain pipe to the outlet 3 as needed. Note that in this embodiment, the combinations of reducing sockets 21, reducing increases 30, 31, and reducing 45° elbows 32, 33 shown in Figures 7a to 7d are merely examples; any combination is possible depending on the diameter and inclination of the upstream and downstream drain pipes, and various adapters can be attached as needed.

The backflow suppression joint 1 of this embodiment includes a valve pipe 5 that communicates with the inlet 2 and protrudes downward from the inlet 2, curving inward towards the interior of the body 4, so as to penetrate the wall surface of the body 4 (Figures 7a to 7d). The valve pipe 5 does not necessarily need to protrude entirely into the interior of the body 4 in the circumferential direction; for example, a portion of the valve pipe 5, such as the upper half in the circumferential direction, may protrude into the interior of the body 4. The protruding portion of the valve pipe 5 may be integrally formed with the body 4, or it may be configured as a separate component detachable from the body 4.

Furthermore, a valve seat portion 50 is formed at the open end of the valve pipe 5, which is inclined to approach the inlet 2 from top to bottom. The valve seat portion 50 functions in cooperation with the valve body 6 (described later) by contacting the valve body 6, thereby preventing backflow of wastewater.

In this embodiment, by providing the valve pipe 5, the wastewater flowing horizontally from the inlet 2 into the body 4 can be reliably and smoothly deflected downwards. Furthermore, since the valve pipe 5 is cylindrical, if the opening surface cut off by a plane perpendicular to the pipe axis of the valve pipe 5 is used as the valve seat portion 50 at the opening end, the valve seat portion 50 can be formed in a substantially circular shape. The shape of the valve body 6 that contacts the valve seat portion 50 can also be substantially circular, thus simplifying design and manufacturing.

Furthermore, as described above, the valve seat portion 50 is inclined such that the protrusion decreases from the top to the bottom. Therefore, the valve body 6, which is suspended from the valve seat portion 50 so as to be able to open and close, forms a gap between itself and the valve seat portion 50 under normal conditions, ensuring smooth flow of forward-flowing wastewater. In abnormal situations (when backflow occurs), the pressure of the reverse-flowing wastewater causes the valve body 6 to contact the valve seat portion 50, effectively suppressing backflow of wastewater.

In this embodiment, the joint body 10 is integrally formed from a plastic material. There are no particular limitations on the material used for the joint body 10; mainly known materials such as plastics can be used. However, polyvinyl chloride resin is preferred from the viewpoint of high strength, water resistance, and ease of molding.

<Lid part>
Figure 8 shows a perspective view from above of the cover 8 and valve body 6 of the backflow suppression joint 1 according to this embodiment, and Figure 9 shows a perspective view from below of the cover 8 and valve body 6 shown in Figure 8. Figure 10 shows a front view of the cover 8 and valve body 6 shown in Figures 8 and 9, Figure 11 shows a side view of the cover 8 and valve body 6 shown in Figures 8 and 9, and Figure 12 shows an exploded view of the cover 8 and valve body 6 shown in Figures 8 and 9.

As shown in Figures 7a-7d and 8-12, the lid 8 has a thick, roughly disc-shaped form, and the valve body 6 is pivotally supported on its lower surface via a suspension arm 82 extending downwards. Furthermore, a pair of triangular handles 800 are formed on the upper surface of the lid 8 for gripping and rotating it. While polyvinyl chloride resin is used for both the lid 8 and the valve body 6, there are no particular limitations on the materials used; primarily known materials such as plastics can be used.

More specifically, as shown in Figure 12, the lid 8 consists of a lid body 80 having a handle 800 for opening and closing the inspection port 7, a cap portion 81 fitted to the lower part of the lid body 80, and a suspension arm 82 integrally molded with the cap portion 81 and extending downward from the lower surface of the cap portion 81. In other words, in this embodiment, the lid body 80 and the cap portion 81 are configured as separate and independent parts, and the lid body 80 and the cap portion 81 are rotatable relative to each other in the circumferential direction.

Furthermore, a pair of auxiliary handles 813 (Figure 12) are provided on the upper surface of the cap portion 81 to facilitate gripping the cap portion 81. On the lower surface of the cap portion 81, a planar bulge 810 with a different inclination angle from the upper surface of the cap portion 81 is formed to prevent the valve body 6 from unnecessarily rotating too far toward the inspection port 7, i.e., toward the opening side.

The shape and structure of the bulge portion 810 are not particularly limited as long as they can restrict the rotation of the valve body 6 within a certain range. In this embodiment, the bulge portion 810 is provided so as to occupy most of the internal space of the inspection port 7, and its restricting surface 811 is inclined to approach the valve body 6 from bottom to top (Figures 7a to 7d). Therefore, the backflow water rising upward from the outlet 3 collides with the restricting surface 811 of the bulge portion 810 and is converted into a flow that pushes the valve body 6 in a direction that closes it from the downstream side, thus making the closing action of the valve body 6 by the backflow water more reliable. Furthermore, when the bulge portion 810 is opened until the valve body 6 contacts it, it forms a downward-curving flow path inside the joint body 10 so as to be continuous with the ceiling portion of the valve pipe 5. Therefore, even if a large amount of wastewater flows horizontally from the inlet 2, the wastewater can be reliably and smoothly deflected downward.

Furthermore, in this embodiment, the lower surface of the cap portion 81 is provided with a convex second engaging portion 812 that can be fitted with the concave first engaging portion 71 provided on the inner circumferential surface of the inspection opening 7 described above, and is positioned opposite to it using the side surface of the bulging portion 810. The shape and structure of the second engaging portion 812 are not particularly limited as long as it can be fitted with the concave first engaging portion 71; for example, it may be a projection extending vertically independently from the back surface of the cap portion 81.

In this embodiment, a groove 814 (Figure 12) is formed on the side surface (circumferential surface) of the cap portion 81, and a packing 83 made of elastomer material is fitted into the groove 814 to improve sealing with the inspection opening 7 (see Figures 7a to 7d). In this embodiment, the lid portion 8 is composed of a lid body 80 and a cap portion 81 with a suspension arm 82 as separate, independent parts, but these may be formed as a single integrated part.

In this embodiment, when closing the inspection opening 7 using the lid portion 8, first, a pair of convex second engaging portions 812 provided on the cap portion 81 are fitted into a pair of concave first engaging portions 71 provided inside the inspection opening 7. The cap portion 81, which supports the valve body 6, is supported from below by the stepped portion 70 inside the inspection opening 7, and is fixed to the inspection opening 7 so as not to rotate in the circumferential direction by the engagement of the second engaging portions 812 and the first engaging portions 71.

Next, after setting the cap portion 81 inside the inspection port 7, the lid body 80 is placed on top of the cap portion 81 inside the inspection port 7. This ensures that the cap portion 81 is sandwiched between the lid body 80 and the stepped portion 70 of the inspection port 7 without any looseness or rotation. As a result, the valve body 6 supported by the cap portion 81 is precisely set in its predetermined position and can accurately contact the valve seat portion 50 inside the joint body 10.

Furthermore, when removing the cover 8 to open the inspection port 7, the valve body 6 can be easily removed by removing the cover body 80 and cap portion 81 from the inspection port 7 using the reverse procedure described above. Also, if the cover body 80 and cap portion 81 are integrally formed, the valve body 6 can be removed together with the cover 8 when it is removed from the inspection port 7.

As shown in Figures 1-4, 6, 8, and 9, the backflow prevention joint 1 of this embodiment is equipped with a locking mechanism 9 to prevent the lid 8 from detaching from the inspection port 7 due to an increase in water or air pressure inside the joint 1. In this embodiment, the locking mechanism 9 uses a bayonet mechanism that prevents the lid 8 from detaching from the inspection port 7 by rotating the lid body 80 circumferentially relative to the inspection port 7. More specifically, the locking mechanism 9 consists of a pair of crank-shaped projections 90 provided at opposing positions 180° apart on the side surface (circumferential surface) of the lid body 80, and a pair of crank-shaped notches 91 provided at opposing positions 180° apart on the receiving end of the inspection port 7.

Therefore, the lid 8 is locked in place without rotation by setting the cap portion 81, which supports the valve body 6, into the inspection opening 7, and then fitting the lid body 80 into the receiving opening of the inspection opening 7. This locks the cap portion 81 from unintended detachment without further rotation. Note that in the bayonet mechanism described above, the notch 91 does not necessarily have to be a crank-shaped projection; for example, it could be a simple rod-shaped projection. Furthermore, the locking mechanism 9 does not necessarily have to be a bayonet mechanism. Especially when the lid body 80 and the cap portion 81 are integrally formed, known engagement means such as a hook that locks the lid 8 from above can also be used.

<Valve body>
As shown in Figures 7a to 7d and 8 to 12, in this embodiment, the valve body 6 has a circular shape so that it can contact the circular valve seat portion 50 in a liquid-tight manner when viewed from the front (Figure 10), and in a side view, it has a recess 60 that is recessed from the downstream side to the upstream side so that it receives a large force (resistance) from reverse flow drainage and a small force (resistance) from forward flow drainage (Figures 8 and 11).

The valve body 6 is supported so as to be rotatable relative to the valve seat 50, and there are no particular limitations on the support position or method. For example, it may be supported by the inner wall of the joint body 10, the valve tube 5, or the cover 8.

In this embodiment, the valve body 6 has a horizontally oriented L-shaped support arm 61 at its upper part, and is pivotally supported to the suspension arm 82 of the cover 8 via the support arm 61, either by a pin or directly. Furthermore, when the cover 8 is set in a predetermined position within the inspection opening 7, the valve body 6 is pivotally supported above the valve tube 5 and offset towards the inlet 2 side from the open end of the valve tube 5 (valve seat 50) (at a pivot point p), allowing it to open and close relative to the valve seat 50. It is preferable that the axial hole of the valve body 6 be formed slightly larger than the diameter of the pin shaft to allow the valve body 6 to rotate smoothly. To improve the sealing performance with the valve seat 50, the hole may be elongated to prevent play between the pin and the valve body 6 when it contacts the valve seat 50.

Therefore, when the valve body 6 is suspended, it is positioned at an inclination so that it approaches the inlet 2 from top to bottom, as shown in Figures 7a to 7d. When the valve body 6 is positioned at an inclination as described above, backflow water flowing horizontally from the outlet 3 towards the front of the valve body 6, and backflow water rising upward from the outlet 3, will collide with the recessed downstream surface of the valve body 6, rather than the upstream surface. This makes the closing action of the valve body 6 by the backflow water more reliable.

Furthermore, as described above, by positioning the pivot point p of the valve body 6 at a location offset towards the inlet 2 side from the valve seat portion 50, the trajectory of the lower end of the valve body 6—that is, the trajectory of the part of the valve body 6 furthest from the pivot point p—approaches the inlet 2 and the valve seat portion 50. Therefore, without changing the opening and closing angle of the valve body 6, the range of motion of the valve body 6 in the outlet region of the valve tube 5 can be substantially narrowed, allowing the backflow suppression joint 1 to be made more compact.

More specifically, as shown in Figure 7a, the valve body 6 is preferably pivotally supported at a pivot point p that is offset such that L/D is preferably 0.15 to 0.45, more preferably 0.20 to 0.40, when D (mm) is the outer diameter of the open end (valve seat portion 50) of the valve tube 5 and L (mm) is the distance from the open end face of the valve tube 5 to the pivot point p of the valve body 6. In this case, the center of gravity of the valve body 6 will be located downstream of the contact surface that abuts the valve seat portion 50 when the valve body 6 is suspended.

If L/D is set to less than 0.15, the valve body 6 cannot be sufficiently tilted so that the backflow water rising upward from the outlet 3 first strikes the downstream surface of the valve body 6. This makes the valve body 6 more likely to move in the opening direction, preventing sufficient blockage of the backflow water. Furthermore, it becomes impossible to narrow the range of motion of the valve body 6 in the outlet region of the valve pipe 5 to the extent that it contributes to the compactness of the backflow suppression joint 1. On the other hand, if L/D is set to more than 0.45, space must be secured for the movement of the support arm 61 of the elongated valve body 6, resulting in the undesirable consequence of making the joint body 10 unnecessarily large.

Furthermore, in the backflow suppression joint 1 of this embodiment, a stopper (not shown) may be provided at the pivot point p of the valve body 6 to prevent the valve body 6 from rotating unnecessarily too far toward the inspection port 7, i.e., toward the opening side. If a stopper is provided at the pivot point p of the valve body 6 as described above, the bulge 810 provided on the lower surface of the cover portion 8 for a similar purpose can be omitted.

Furthermore, in the backflow suppression joint 1 of this embodiment, a buoyancy generating section (not shown) having a specific gravity less than that of water may be provided upstream of the valve body 6 and on the inlet 2 side of the vertical plane passing through the fulcrum p of the valve body 6. By positioning the buoyancy generating section eccentrically upstream of the valve body 6 in this way, when backflow occurs, the buoyancy generating section is pulled upward by the backflow rising from the outlet 3 in the direction of closing the valve body 6, thereby more reliably preventing malfunction of the valve body 6.

1. Backflow prevention fitting 10. Fitting body 2. Inlet 20. Receiving port step 21. Reducing socket 3. Outlet 30. First reducing increaser 31. Second reducing increaser 32. First reducing 45° elbow 33. Second reducing 45° elbow 4. Body 5. Valve tube 50. Valve seat 6. Valve body 60. Recess 61. Support arm 7. Inspection port 70. Step 71. First engaging part 8. Cover 80. Cover body 800. Handle 81. Cap 810. Bulging part 811. Regulating surface 812. Second engaging part 813. Auxiliary handle 814. Groove 82... Suspension arm 83... Packing 9... Locking mechanism 90... Projection 91... Notch a... First central axis b... Second central axis c... Third central axis p... Pivot point D... Outer diameter of the open end (valve seat) (mm)
L... Distance from the opening end face to the pivot point of the valve body (mm)

Claims (12)

Inlet and
Outlet and
A body portion connecting the inlet and the outlet,
A valve tube is provided that communicates with the inlet and protrudes into the interior of the body,
A valve seat formed at the open end of the valve tube, which is inclined to approach the inlet from the top to the bottom; and a valve body rotatably supported at the upper part of the valve tube and at a position offset toward the inlet from the open end of the valve tube.
A backflow suppression joint equipped with [a specific feature]. The backflow suppression joint according to claim 1, characterized in that, when the outer diameter of the open end of the valve tube is D (mm) and the distance from the open end face of the valve tube to the pivot point of the valve body is L (mm), L/D is 0.15 or more and 0.45 or less. The backflow suppression joint according to claim 1, characterized in that, when the valve body is suspended, the center of gravity of the valve body is positioned downstream of the contact surface that contacts the valve seat portion of the valve body. The backflow suppression joint according to claim 1, characterized in that, when the valve body is suspended, the valve body is inclined such that the contact surface with the valve seat portion approaches the inlet side as it moves from the top to the bottom. The backflow suppression joint according to claim 4, characterized in that the valve body has a recess that extends from the downstream side to the upstream side. The backflow suppression joint according to claim 1, characterized in that the inlet is formed to have a first central axis extending in the horizontal direction, and the outlet is formed to have a second central axis extending in the vertical direction. An inspection port having a third central axis that extends from the body and extends upward diagonally away from the inlet,
The backflow suppression joint according to any one of claims 1 to 6, further comprising a cover that can be detachably attached to the inspection port, wherein the valve body is rotatably supported by the cover. The lid portion includes a cap portion that is attached to the inspection opening so as not to rotate in the circumferential direction,
The backflow suppression joint according to claim 7, comprising a lid body that is rotatably mounted circumferentially on the cap portion with respect to the inspection opening, and the valve body being supported by the cap portion. The backflow suppression joint according to claim 8, characterized in that the inner circumferential surface of the inspection opening is provided with a first engaging portion that fixes the cap portion so as not to rotate in the circumferential direction relative to the inspection opening, and the cap portion is provided with a second engaging portion that engages with the first engaging portion. The backflow suppression joint according to claim 9, further comprising a locking means to prevent the lid from detaching from the inspection port due to an increase in the pressure of water or air inside the body, wherein the locking means is a bayonet mechanism that engages with the inspection port by rotating the lid circumferentially relative to the inspection port. The backflow suppression joint according to claim 7, characterized in that the diameter of the inspection port is the same as the diameter of the outlet. The backflow suppression joint according to claim 11, characterized in that the diameter of the outlet is larger than the diameter of the inlet.