JP2024099399A - Backflow prevention device and drainage basin equipped with backflow prevention device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backflow prevention device that can be installed without impeding a flow even in a drainage system with a large amount of forward flow drainage, can operate to reliably close a backflow prevention valve when backflow water occurs, has excellent durability and maintainability, and can be easily installed.

MEANS FOR SOLVING THE PROBLEM: A backflow prevention device provided by the present invention comprises: a cylindrical valve pipe having an opening/closing port and a connection port; valve seat part formed at an open end of the valve pipe on an opening/closing side; and a valve body supported rotatably at an upper part on the opening/closing side of the valve pipe, the upper part of the valve pipe is provided with a bearing part for supporting the valve body, and a bearing part is provided with a stopper that can be removed in whole or in part, and that restricts a rotation range of the valve body by contacting the stopper with the valve body.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a backflow prevention device equipped with a backflow prevention valve, and in particular to a backflow prevention device that is provided with a stopper that can variably regulate the opening angle of the backflow prevention valve, and further with a level mount and marked lines to facilitate the installation of the backflow prevention device.

Generally, wastewater discharged from drainage facilities such as toilets, bathrooms, and kitchens in homes is collected in a drainage manhole installed on the housing estate via drainage pipes connected to each drainage facility, and the wastewater collected in the drainage manhole is then discharged into the main sewer pipe via a public manhole or manhole.

In addition, backflow prevention (control) devices that are attached to the inlet of a drainage manhole or the like to prevent backflow water generated in downstream drainage equipment such as a sewer main from entering a home include a type in which the valve body is basically closed except when normal drainage is flowing in order to maximize the deodorizing effect, as described in JP 2008-261222 A (Patent Document 1), and a type in which the valve seat is tilted and the backflow prevention valve is basically open except when backflow water is flowing, as described in JP 2020-153508 A (Patent Document 2), with an emphasis on preventing clogging due to foreign objects, etc., are widely known.

In recent years, the amount of normal wastewater passing through catch basins has been increasing due to increased precipitation caused by global warming and the diversification of drainage facilities, which has led to more complex drainage routes. On the other hand, backflow water is occurring frequently in drainage routes due to abnormal weather caused by global warming, so backflow prevention devices are required to open the backflow prevention valve wide under normal circumstances to allow a large amount of forward flow wastewater to flow, and at the same time, to reliably close the backflow prevention valve in abnormal situations to prevent backflow of wastewater.

In addition, in the backflow prevention devices described above, the backflow prevention valve is opened and closed more frequently than before, and wear on the valve body, valve seat, packing, etc. is also more severe, so there is a demand for higher durability and advanced maintainability than before.

In addition, there was a strong demand for the development of a backflow prevention device that could be easily installed even in locations with complicated drainage paths and installation space restrictions, such as those described above.

JP 2008-261222 A JP 2020-153508 A

However, in the backflow prevention devices described in Patent Documents 1 and 2, the check valve is not restricted and is configured to be fully open to an angle of 90° or more from the valve seat in order to ensure a smooth flow even when the amount of wastewater is large. Therefore, if backflow water occurs when the check valve is almost fully open, the check valve cannot be closed properly, allowing wastewater to backflow.

Furthermore, for example, if the backflow prevention device is installed at a position away from the bottom of the catch basin or the invert, backflow water will not only flow from downstream to upstream, but will also cause a flow from below the valve body to above, raising the liquid level. As a result, as described in Patent Document 2 in particular, in a backflow prevention device that basically keeps the backflow prevention valve open except when backflow water is flowing, the valve body will move in the opening or closing direction depending on the direction in which the backflow water collides with the valve body, making the opening and closing operation extremely unstable.

Furthermore, as described in Patent Document 1, even in a backflow prevention device of the type in which the backflow prevention valve is basically closed except when normal wastewater flows, if it is installed at a downward tilt downstream from the installation angle planned at the time of design, the backflow prevention valve is usually suspended vertically almost directly below its rotation axis, while the valve seat against which the valve body abuts is positioned at an angle that moves away from the vertical the further downward it goes. In other words, even in the backflow prevention device described in Patent Document 1, the valve body is positioned at a large angle from the valve seat, which can cause the same problems as a backflow prevention device of the type in which the backflow prevention valve is basically open except when backflow water flows.

On the other hand, if the valve disc is permanently restricted from opening too far from the valve seat, the angle at which the valve disc opens will be insufficient in drainage paths that naturally have a large amount of drainage flowing from upstream to downstream, which can hinder the smooth flow of drainage and make it more susceptible to clogging.

The present invention aims to provide a backflow prevention device that can be installed in a drainage system that has a large amount of normal drainage (forward flow drainage) without impeding the flow, and that can be operated to reliably close the backflow prevention valve (valve body) when backflow occurs, and that has excellent durability, ease of maintenance, and can be easily installed, as well as a drainage manhole equipped with a backflow prevention device.

After extensive research into the support structure of the valve body (backflow prevention valve) of the backflow prevention device, the inventors discovered that by providing a stopper on the movable part of the valve body that limits the rotation angle (rotation range) at which the valve body opens from the valve seat within a certain range, and by making it possible to change the height of the stopper by removing all or part of the stopper, it is possible to solve the above-mentioned conflicting problems of making the valve body easy to open for forward flow drainage while making it easy to close for backflow water, and thus completed the present invention.

That is, according to the present invention, a backflow prevention device is provided that includes a cylindrical valve pipe having an opening/closing port and a connection port, a valve seat formed at the open end of the valve pipe on the opening/closing port side, and a valve body supported rotatably at the upper part of the valve pipe on the opening/closing port side, the upper part of the valve pipe is provided with a bearing part for supporting the valve body, and the bearing part is provided with a stopper that can be removed in whole or in part and that abuts against the valve body to limit the rotation range of the valve body.

Therefore, in the present invention, it is preferable that the stopper has a through hole, and that the stopper is configured so that the height of the stopper (contact position with the valve body) can be changed by removing the material above the through hole. In addition, the through hole does not necessarily have to be an open hole shape, and may be a through slit or a through perforation, etc.

In order to make the stopper easier to cut out, it may be formed, for example, from a plate-like member thinner than the bearing portion or a removal block defined by a cutout groove thinner than the bearing portion.

According to the present invention, for example in a drainage system where backflow water frequently occurs, the stopper (which keeps the stopper height high) restricts the rotation angle (rotation range) of the valve body when it is fully open to within a vertical direction or an angle closer to the valve seat than the vertical direction, so that when backflow water occurs, the valve body can be positioned at an angle where it is more likely to be subjected to a force in the closing direction by backflow water.

In addition, for example, in a drainage system that has a large amount of forward flow drainage that flows from upstream to downstream, removing all or part of the stopper (lowering the stopper height) allows the valve body to rotate to a position (angle) away from the valve seat side rather than vertically, allowing for a smooth flow of forward flow drainage and effectively preventing clogging due to foreign matter, etc.

In this way, the backflow prevention device of the present invention is provided with a stopper that abuts against the valve body on the bearing portion that supports the valve body and can change the height of that abutment, so that the rotation angle (rotation range) at which the valve body opens from the valve seat portion can be limited or adjusted depending on the amount of forward flow drainage and the frequency and amount of backflow water.

As a result, the backflow prevention device of the present invention, regardless of whether it is a type in which the valve body is basically open or a type in which the valve body is basically closed, can be installed in a drainage system with a large amount of forward flow drainage, a drainage system in which backflow water occurs frequently, or a drainage system that has both characteristics, by adjusting the contact height of the stopper while maintaining a balance between these two, allowing for a smooth flow of forward flow drainage and yet operating to stably close the valve body when backflow water occurs.

In the backflow prevention device of the present invention, the valve body has an arm portion, and the arm portion may be configured to limit the rotation range of the valve body by abutting against a stopper.

In addition, in the backflow prevention device of the present invention, the valve pipe may be provided with an abutment receiving portion at the top near the opening and closing port, and the abutment receiving portion may be configured to abut against the arm portion of the valve body, thereby limiting the rotation range of the valve body.

In the present invention, by providing an arm portion on the valve body, the pivot position (rotation axis) of the valve body at the top of the valve tube can be freely positioned. In addition, by configuring the arm portion to abut against the abutment receiving portion at the top of the valve tube, excessive rotation of the valve body toward the closing side can be suppressed, and damage to the valve seat portion, the valve body abutting against the valve seat portion, and the valve body packing can be prevented.

In the backflow prevention device of the present invention, an axial hole is provided in the arm portion and bearing portion of the valve body, a sleeve with a low friction coefficient is attached to the axial hole, and the valve body may be removably attached to the bearing portion via a bolt and nut inserted into the sleeve. Attaching the sleeve facilitates rotation of the valve body and prevents wear on the axial hole, improving durability. In addition, the use of bolts and nuts makes it extremely easy to attach and remove the valve body, improving the maintainability of the backflow prevention device.

In addition, in the backflow prevention device of the present invention, a level mount portion having a flat surface parallel to the rotation axis of the valve body and on which a level can be placed may be provided at the top of the valve pipe. Furthermore, a marked line parallel to the central axis of the opening and closing of the valve pipe may be displayed on the top of the valve pipe. The installation of the level mount portion and the display of the marked line make it easy to center the backflow prevention device using a level or marked line, and the backflow prevention device can be easily attached to a drainage manhole, etc.

In the present invention, the opening/closing port and the connecting port of the valve pipe may be formed so that the central axis of the opening/closing port and the central axis of the connecting port are arranged parallel to each other and eccentrically. By arranging the opening/closing port and the connecting port of the valve pipe so that their central axes are eccentric to each other, it becomes possible to easily increase or decrease the diameter of the connecting port by changing the design while keeping the outer shape (diameter, etc.) of the opening/closing port and the valve body constant. Furthermore, even if the opening/closing port and the connecting port of the valve pipe have different diameters, the bottom of the valve pipe can be made flush without any steps, so clogging due to foreign matter, etc. can be effectively prevented.

In the backflow prevention device of the present invention, when the connection port of the valve pipe is arranged to open horizontally, the valve pipe may be curved or bent midway so that the opening and closing port opens diagonally downward. If the valve pipe is curved or otherwise formed so that the opening and closing port opens diagonally downward, for example, when the backflow prevention device is attached to the inlet of a drainage basin having an invert, forward flow wastewater can flow smoothly toward the invert and the outlet. In addition, under normal conditions, a gap is formed between the valve body and the valve seat portion formed at the opening end, ensuring the smooth flow of a small amount of forward flow wastewater, effectively preventing clogging due to foreign matter, etc.

In addition, in the backflow prevention device of the present invention, the center of gravity of the valve disc may be located upstream of the contact surface of the valve disc so that when the valve disc is supported, the contact surface with the valve seat is inclined away from the valve seat from top to bottom. If the center of gravity of the valve disc is located upstream of the contact surface of the valve disc, the valve disc will normally be inclined downstream from the vertical direction to form a gap with the valve seat, ensuring the smooth flow of a small amount of forward flow drainage and effectively preventing clogging due to foreign matter, etc.

Furthermore, by attaching the backflow prevention device of the present invention to the inlet of a drainage manhole that has an inlet and an outlet, the effects achieved by the backflow prevention device of the present invention described above can also be enjoyed in the drainage manhole.

In this specification, "horizontal" does not mean only the horizontal direction in the strict sense, but is used in a range that includes the degree of gradient that is set when drainage is made to flow horizontally. Also, "vertical" does not mean only the vertical direction in the strict sense, but is used in a range that includes the degree of error that occurs when manufacturing and installing joints.

According to the present invention, a backflow prevention device is provided that includes a cylindrical valve pipe having an opening and closing port and a connection port, a valve seat formed at the open end of the valve pipe on the opening and closing port side, and a valve body supported rotatably at the upper part of the valve pipe on the opening and closing port side, and the backflow prevention device is characterized in that a bearing part for supporting the valve body is provided at the upper part of the valve pipe, and the bearing part is provided with a stopper that can be removed in whole or in part and that abuts against the valve body to limit the rotation range of the valve body.

In this case, it is preferable that the stopper has a cut hole, and that the height of the stopper (contact position with the valve body) can be changed by removing the material above the cut hole. The stopper may also be formed, for example, from a plate-like material that is thinner than the bearing portion, or a removal block that is partitioned by a cut groove that is thinner than the bearing portion.

According to the present invention, the bearing portion that supports the valve body is provided with a stopper that abuts against the valve body, so that the rotation angle (rotation range) of the valve body opening from the valve seat portion can be limited or adjusted depending on the amount of forward flow drainage and the frequency and amount of backflow water. As a result, the backflow prevention device of the present invention, regardless of whether it is a type in which the valve body is basically open or a type in which the valve body is basically closed, can allow smooth forward flow drainage by adjusting the abutment height of the stopper while balancing these factors, even if it is installed in a drainage system with a large amount of forward flow drainage, a drainage system with a high frequency of backflow water, or a drainage system with both characteristics, and yet can operate to stably close the valve body when backflow water occurs.

In addition, according to the present invention, a level mount and a marked line can be provided on the valve pipe, making it easy to center the backflow prevention device using the level and the marked line, and the backflow prevention device can be easily installed.

Furthermore, according to the present invention, the central axes of the opening and closing port of the valve pipe and the connecting port can be arranged parallel to each other and eccentrically, so that it is possible to easily change the design of only the diameter of the connecting port without changing the external shape (diameter, etc.) of the opening and closing port and the valve body, and the bottom of the valve pipe can be made flush without any steps, effectively preventing clogging due to foreign matter, etc.

1 is a perspective view of a backflow prevention device according to a first embodiment of the present invention; 2 is a longitudinal cross-sectional view of the valve pipe taken along line AA in the backflow prevention device shown in FIG. 1. 2 is a longitudinal cross-sectional view of the backflow prevention device shown in FIG. 1 taken along the line AA (where the valve body 3 is in an open state), and an enlarged view of a portion of the vicinity of the bearing portion in the longitudinal cross-sectional view. 4 is a partially enlarged view showing a state before a stopper formed in a bearing portion of the backflow prevention device according to the first embodiment is removed. FIG. 4 is a partially enlarged view showing the backflow prevention device according to the first embodiment after a stopper formed in a bearing portion has been removed. FIG. 2 is a plan view of the valve pipe seen from directly above in the backflow prevention device shown in FIG. 1. 1 is a perspective view showing a backflow prevention device according to a first embodiment attached to a catch basin. FIG. FIG. 5 is a perspective view of a backflow prevention device according to a second embodiment of the present invention. 7 is a longitudinal cross-sectional view of the valve pipe taken along line BB in the backflow prevention device shown in FIG. 6. FIG. 8 is an enlarged view of a portion of the backflow prevention device near a bearing portion in the longitudinal cross-sectional view shown in FIG. 7. 11 is a perspective view showing a backflow prevention device according to a second embodiment attached to a catch basin. FIG.

Below, a backflow prevention device and a drainage basin equipped with a backflow prevention device according to one embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the examples shown below, and various modifications are possible within the scope of the technical concept of the present invention.

First Embodiment
Fig. 1 shows a perspective view of a backflow prevention device 1 according to a first embodiment of the present invention. Fig. 2 shows a longitudinal section of the valve pipe 2 taken along line A-A in the backflow prevention device 1 according to the first embodiment, and Fig. 3a shows a longitudinal section of the backflow prevention device 1 according to the first embodiment taken along line A-A (where the valve body 3 is in an open state) and an enlarged view of a portion of the longitudinal section near the bearing portion 23. Fig. 3b shows a partially enlarged view of the backflow prevention device 1 according to the first embodiment before the stopper 24 formed on the bearing portion 23 is removed, and Fig. 3c shows a partially enlarged view of the backflow prevention device according to the first embodiment after the stopper formed on the bearing portion is removed.

As shown in Figs. 1 and 2, the backflow prevention device 1 of the first embodiment includes a cylindrical valve pipe 2 having an opening/closing port 20 and a connection port 21, and a valve body 3 supported rotatably at the upper part of the valve pipe 2 on the opening/closing port 20 side. A valve seat 22 is formed at the open end of the valve pipe 2 on the opening/closing port 20 side, which closes the opening/closing port 20 by abutting against the peripheral edge of the valve body 3. In addition, it is preferable that a packing made of an elastomer material such as synthetic rubber is attached to the valve seat 22 or the peripheral edge of the valve body 3 that abuts against the valve seat 22 in order to improve the sealing between the valve seat 22 and the valve body 3 when closed, and in this embodiment, a synthetic rubber packing 34 (see Fig. 3a) is attached to the peripheral edge of the valve body 3.

2, the opening/closing port 20 and the connection port 21 of the valve pipe 2 are formed so that the central axis a of the opening/closing port 20 and the central axis b of the connection port 21 are arranged parallel to each other and eccentrically. In this embodiment, the central axes a, b of the opening/closing port 20 and the connection port 21 of the valve pipe 2 are arranged eccentrically to each other, so that the diameter of the connection port 21 can be easily enlarged or reduced by design changes while the outer shape (diameter, etc.) of the opening/closing port 20 and the valve body 3 is kept constant. In addition, even if the opening/closing port 20 and the connection port 21 of the valve pipe 2 have different diameters, the bottom of the valve pipe 2 can be made flush without any steps, so clogging due to foreign matter can be effectively prevented. In this embodiment, the shape of the connection port 21 is basically a spigot shape, but it may also be a socket shape (not shown).

As shown in Fig. 1, 3b and 3c, a bearing portion 23 for rotatably supporting an arm portion 31 of a valve body 3 (described later) is provided on the upper side of the outer periphery of the valve tube 2. In the first embodiment, the bearing portion 23 is made of a pair of pillar members 230 extending upward from the outer periphery of the valve tube 2, and reinforcing ribs 231 for preventing deformation of the valve tube 2 in the circumferential direction are formed on the side of the pillar members 230, and are arranged in a gate shape. In addition, each pillar member 230 is formed with an axial hole 232 (Fig. 2) through which a bolt 4 for supporting the valve body 3 can be inserted.

In the first embodiment, a stopper 24 (Fig. 3b) is provided between a pair of column members 230 of the bearing portion 23 of the valve pipe 2 so as to connect both column members 230. The stopper 24 has a through hole 240 formed to connect both column members 230 so that it can be removed in whole or in part, and the contact height of the stopper 24 can be easily changed by cutting both ends of the portion of the stopper 24 above the hole 240 with a saw or a utility knife (see Fig. 3c).

The cut holes 240 do not necessarily have to be open holes, and may be slits or perforations. In addition, multiple cut holes 240, slits, perforations, etc. may be arranged in multiple stages, and the contact height of the stopper 24 may be changed in multiple stages by removing the upper stopper 24 portion of each cut hole 240, etc. Furthermore, the cut holes 240, etc. may be arranged so as to contact the outer circumferential surface of the valve tube 2, so that the entire stopper 24 formed on the outer circumferential surface of the valve tube 2 can be removed.

Although not shown, the stopper 24 can also be formed as a plate-like member thinner than the bearing portion 23 so that it can be easily cut using a saw or a utility knife, or as a removal block defined by a cutout groove thinner than the bearing portion 23.

In this way, unlike the reinforcing ribs 231 etc. that are permanently arranged, the stopper 24 has cut holes 240 etc. and portions that are thinner than other portions such as the pillar members 230 of the bearing portion 23, so that all or part of the stopper 24 can be easily removed using a saw, a utility knife, etc.

The valve element 3 attached to the valve pipe 2 comprises a substantially circular valve body 30 that abuts against the valve seat 22 of the valve pipe 2 as shown in Figs. 1 and 3a, and an arm portion 31 that extends continuously from the upper end of the valve body 30 to the back side (upstream side) of the valve element 3 so that the valve element 3 is supported by the bearing portion 23 of the valve pipe 2. On the side of the arm portion 31 that is attached to the bearing portion 23, a shaft hole 310 (Fig. 3a) is formed through which the bolt 4 for supporting the valve element 3 can be inserted.

A first abutment portion 311 having a planar shape is formed on the outer periphery of the shaft hole 310 of the arm portion 31, which abuts against the stopper 24 to regulate the rotation angle (rotation range) of the valve body 3 on the fully open side, and a second abutment portion 312 having a planar shape is formed at a position rotated approximately 100° from the first abutment portion 311 around the shaft hole 310, which abuts against the abutment receiving portion 25 formed at the apex near the opening/closing port 20 of the valve tube 2 to regulate the rotation angle (rotation range) of the valve body 3 on the fully closed side.

In the first embodiment, as shown in Figs. 1 and 3c, the stopper 24 portion above the cut hole 240 (see Fig. 3b) is removed, and the abutment between the first abutment portion 311 of the arm portion 31 of the valve body 3 and the stopper 24 portion above the cut hole 240 is released. However, in this embodiment, even if the stopper 24 portion above the cut hole 240 is removed, the sub-stopper 241, which is lower in height than the removed stopper 24 portion, remains as the remaining portion of the stopper 24. Therefore, the upper end of the sub-stopper 241 abuts against the arm portion 31, limiting the opening and closing angle of the valve body 3 relative to the valve seat portion 22 to a maximum of approximately 100° (see Fig. 3a).

As mentioned above, the stopper 24 may be provided with a cut hole 240 in contact with the outer circumferential surface of the valve tube 2, so that the entire stopper 24 formed on the outer circumferential surface of the valve tube 2 can be removed. In this case, the valve body 3 can be rotated in a direction opening by 100° or more relative to the valve seat portion 22 until the first abutment portion 311 of the arm portion 31 abuts against the outer circumferential surface of the valve tube 2.

In the first embodiment, an inclined surface 242 is provided on the upper part of the sub-stopper 241, and the inclined surface 242 abuts the first abutment portion 311 of the arm portion 31 face-to-face, thereby suppressing local wear and damage of the abutting portion of the sub-stopper 241 and the arm portion 31. Although not shown, the inclined surface 242 may be provided on the portion of the stopper 24 above the cut hole 240 before removal.

On the other hand, when the valve body 3 rotates toward the closing side, the valve body 3 and the valve seat portion 22 come into contact with each other at approximately the same time that the second contact portion 312 of the arm portion 31 comes into contact with the contact receiving portion 25 formed at the top of the valve tube 2. This prevents the valve body 3 from rotating toward the closing side excessively, thereby preventing damage to the valve seat portion 22, the valve body 3, and the packing 34 of the valve body 3.

Thus, in the first embodiment of the backflow prevention device 1, under normal circumstances, the valve body 3 is basically closed except when forward flow drainage is flowing, but by removing the portion of the stopper 24 above the cut hole 240, it can be opened to a rotation range of approximately 100° from the valve seat 22, ensuring a smooth flow of forward flow drainage from upstream to downstream. However, since the valve body 3 cannot be opened to a position (rotation angle) of 100° or more from the valve seat 22 no matter how much the amount of forward flow drainage increases, when backflow water occurs, the valve body 3 is held at an angle that makes it susceptible to collision with backflow water and can operate to close quickly.

The backflow prevention device 1 of the first embodiment can be used in drainage systems in general, but is particularly suitable for use in rainwater systems and rainwater applications. In that case, the backflow prevention device 1 of this embodiment can prevent odors emanating from the downstream drainage equipment from flowing upstream during normal times when rainwater is not flowing.

In the first embodiment, a sleeve (not shown) with a low friction coefficient made of fluororesin or the like can be inserted into the shaft hole 232 of the bearing portion 23 and/or the shaft hole 310 of the arm portion 31. The attachment of the sleeve allows the bolt 4 supporting the valve body 3 to rotate smoothly and prevents wear on the shaft holes 232 and 310, improving durability. In addition, the valve body 3 is attached to the bearing portion 23 by the bolt 4 and nut 40 inserted into the sleeve via the arm portion 31, making it extremely easy to attach and detach the valve body 3, improving the maintainability of the backflow prevention device 1.

In particular, in general backflow prevention devices, the valve body and the bearing part of the valve pipe that supports the valve body are often made of integrally molded plastic resin, etc., so that instead of using other parts such as metal bolts or pins as a means of supporting the valve body, the elasticity (flexibility) of the plastic resin, etc. is used to fit the rotating shaft formed integrally with the valve body into the bearing part of the valve pipe. As a result, it is difficult to easily remove the rotating shaft from the bearing part once it has been fitted into the valve body, and so the development of a backflow prevention device that makes it easy to attach and remove the valve body 3, as in this embodiment, has been eagerly awaited.

In this embodiment, as shown in Figures 1 and 3a, the downstream surface 32 of the valve body 30 is concave from the downstream side to the upstream side. Therefore, for the same flow rate, the resistance force of reverse flow drainage received by the downstream surface 32 of the valve body 30 is greater than the resistance force of forward flow drainage received by the upstream back surface 33 of the valve body 30. Therefore, when a reverse flow occurs, the difference in resistance force generated between the front and back surfaces 32, 33 of the valve body 3 allows the valve body 3 to stably operate to close the opening/closing port 20 of the valve pipe 2.

The center of gravity of the valve body 3 may be located upstream of the contact surface of the valve body 3 so that when the valve body 3 is supported, the contact surface with the valve seat 22 is inclined away from the valve seat 22 as it moves from top to bottom. If the center of gravity of the valve body 3 is located upstream of the contact surface of the valve body 3, the valve body 3 will normally be inclined downstream from the vertical direction to form a gap with the valve seat 22, ensuring the smooth flow of a small amount of forward flow drainage and effectively preventing clogging due to foreign matter, etc.

In this embodiment, the valve pipe 2 and valve body 3 that constitute the backflow prevention device 1 are each integrally molded from a plastic material. There are no particular limitations on the material used for the backflow prevention device 1, and known materials such as plastics can be used, with polyvinyl chloride resin being preferred from the standpoint of high strength, water resistance, ease of molding, etc.

Figure 5 shows a perspective view of the backflow prevention device 1 according to the first embodiment attached to a drainage manhole 5. Note that in Figure 5, only the cylindrical body 50 is shown with a dotted line so that the inside of the drainage manhole 5 can be seen through.

As shown in FIG. 5, the drainage manhole 5 to which the backflow prevention device 1 of the first embodiment is attached has a substantially cylindrical body 50 with a short pipe-shaped inlet 500 and outlet 501 on the side wall, a bottom 51 attached to the lower part of the body 50, a frame part 52 with an inspection hatch attached to the upper part of the body 50, and a substantially disk-shaped lid part 53 detachably attached to the frame part 52. In addition, an upstream connecting pipe 54 and a downstream connecting pipe 55 are attached to the inlet 500 and the outlet 501, respectively, and both connecting pipes 54, 55 protrude into the inside of the body 50. In this embodiment, the backflow prevention device 1 is attached by inserting the connecting port 22 into the internal protrusion of the upstream connecting pipe 54 attached to the inlet 500.

In this embodiment, the catch basin 5 is made of concrete material, but it may also be made of a plastic material such as polyvinyl chloride resin, a metal material such as iron, or an appropriate combination of these materials.

In addition, in the drainage manhole 5, the bottom 51 and/or the frame 52 do not need to be configured as separate parts from the cylindrical body 50, and may be formed integrally. In this embodiment, the upstream connecting pipe 54 of the inlet 500 and the downstream connecting pipe 55 of the outlet 501 both open at a position spaced above the bottom 51, and in order to provide a drop in the drainage, the outlet 501 and the downstream connecting pipe 55 are positioned so that their respective bottoms are lower than the bottoms of the inlet 500 and the upstream connecting pipe 54.

In the drainage manhole 5 of this embodiment, the valve body 3 of the backflow prevention device 1 of the first embodiment can be rotated in an opening direction of approximately 100° relative to the valve seat portion 22 by the sub-stopper 241 (Figure 3a). Therefore, under normal circumstances, the backflow prevention device 1 can freely open the valve body 3 according to the flow rate, regardless of whether the amount of wastewater flowing into the drainage manhole 5 from the upstream connecting pipe 54 (inlet 500) is large or small.

On the other hand, in the event of an abnormality, when wastewater flows back into the drainage manhole 5 from the downstream connecting pipe 55 (outlet 501), the downstream connecting pipe 55 (outlet 501) and the upstream connecting pipe 54 (inlet 500) are open at an upper position away from the bottom 51, so the backflow water flows from the bottom 51 toward the upstream connecting pipe 54 (inlet 500) in such a way that the liquid level rises. However, in this embodiment, the opening 20 (valve seat 22) of the valve pipe 2 of the backflow prevention device 1 is arranged in a vertical plane, so the valve body 3 basically closes the opening 20, and it is possible to reliably prevent the backflow water from entering the upstream connecting pipe 54 (inlet 500).

Second Embodiment
Fig. 6 shows a perspective view of a backflow prevention device 1a according to a second embodiment of the present invention. Fig. 7 shows a vertical cross-sectional view of the valve pipe 2a of the backflow prevention device 1a according to the second embodiment taken along the line B-B, and Fig. 8 shows an enlarged view of a part of the backflow prevention device 1a near the bearing portion 23a in the vertical cross-sectional view of the backflow prevention device 1a according to the second embodiment taken along the line B-B.

The backflow prevention device 1a of the second embodiment has the same configuration as the backflow prevention device 1 of the first embodiment and can achieve the same effects, except that when the connection port 21a of the valve tube 2a is arranged to open horizontally, the valve tube 2a is curved or bent midway so that the other opening/closing port 20a opens diagonally downward, the shape of the connection port 21a is basically a receiving port shape, and the stopper 24a (the portion of the stopper 24a above the cut hole 240a) is in a state before the stopper 24a is removed, so the rotation range of the valve body 3a that abuts against the stopper 24a is more limited than in the first embodiment. Therefore, for the backflow prevention device 1a of the second embodiment, detailed explanations of the parts that have the same configuration and effects as the backflow prevention device 1 of the first embodiment will be omitted here.

The backflow prevention device 1a of the second embodiment is equipped with a cylindrical valve pipe 2a having an opening/closing port 20a and a connection port 21a. Unlike the first embodiment, the opening/closing port 20a is formed so that it opens in a downward diagonal direction by bending the valve pipe 2a. The valve pipe 2a may be curved in a stepwise downward diagonal direction by combining short straight pipes (Figure 7), or may be curved in a continuous downward diagonal direction by using curved pipes, or may be curved in a downward diagonal direction by combining short straight pipes and curved pipes. In addition, although the shape of the connection port 21a is a socket shape in this embodiment, it may also be a spigot shape (not shown).

In the second embodiment, the valve pipe 2a is curved to open the opening/closing port 20a in a downward diagonal direction, so that when the backflow prevention device 1a is attached to the inlet 500a of a drainage basin (Figure 9) having an invert 51a or a bottom, the forward flow drainage can be smoothly guided toward the invert 51a, the outlet 501a (Figure 9) connected to the invert 51a, or the bottom. In addition, in the second embodiment, a gap is formed between the valve body 3a and the valve seat portion 22a of the opening/closing port 20a under normal conditions, so that a smooth flow is guaranteed even if the amount of forward flow drainage is small, and clogging due to foreign matter is effectively prevented.

In the second embodiment, a stopper 24a is provided between a pair of column members 230a of the bearing portion 23a of the valve pipe 2a so as to connect both column members 230a. The stopper 24a has a through hole 240a formed to connect both column members 230a so that it can be easily removed in whole or in part, and both ends of the stopper 24a above the hole 240a can be easily removed by cutting them with a saw or a utility knife, etc., to change the abutment height of the stopper 24a (see Figure 3c).

The cut holes 240a do not necessarily have to be open holes, and may be slits or perforations. In addition, multiple cut holes 240a, slits, perforations, etc. may be arranged in multiple stages, and the contact height of the stopper 24a may be changed in multiple stages by removing the upper stopper 24a portion of each cut hole 240a, etc. Furthermore, the cut holes 240a, etc. may be arranged so as to contact the outer circumferential surface of the valve tube 2a, so that the entire stopper 24a formed on the outer circumferential surface of the valve tube 2a can be removed.

Although not shown, the stopper 24a may be formed as a plate-like member thinner than the bearing portion 23a so that it can be easily cut using a saw or a utility knife, or as a removal block defined by a cutout groove thinner than the bearing portion 23a.

In this way, unlike the reinforcing ribs 231a etc. that are permanently arranged, the stopper 24a has cut holes 240a etc. and portions that are thinner than other portions such as the pillar members 230a of the bearing portion 23a, making it easy to remove all or part of the stopper 24a using a saw, utility knife, etc.

In the second embodiment, the valve body 3a attached to the valve pipe 2a includes a substantially circular valve body 30a that abuts against the valve seat 22a of the valve pipe 2a as shown in Figures 6 and 7, and an arm portion 31a that extends continuously from the upper end of the valve body body 30a to the back side (upstream side) of the valve body 3a in order to support the valve body 3a by the bearing portion 23a of the valve pipe 2a. On the attachment side of the arm portion 31a to the bearing portion 23a, a shaft hole 310a (Figure 7) is formed through which the bolt 4a for supporting the valve body 3a can be inserted. In addition, a flat-shaped abutment portion 311a is formed on the outer periphery of the shaft hole 310a of the arm portion 31a for abutting against the stopper 24a.

A first abutment portion 311a having a flat shape is formed on the outer periphery of the shaft hole 310a of the arm portion 31a, which abuts against the stopper 24a to regulate the rotation angle (rotation range) of the valve body 3a on the fully open side, and a second abutment portion 312a having a flat shape is formed at a position rotated approximately 100° from the first abutment portion 311a around the shaft hole 310a, which abuts against a contact receiving portion 25a formed at the top near the opening/closing port 20a of the valve tube 2a to regulate the rotation angle (rotation range) of the valve body 3a on the fully closed side.

In the second embodiment, as shown in FIG. 7 and FIG. 3b, the portion of the stopper 24a above the cut hole 240a is not removed, so that the opening and closing angle of the valve body 3a relative to the valve seat 22a is limited so that the valve body 3a can only open vertically or closer to the valve seat 22a than vertically by the upper end of the stopper 24a abutting the first abutment portion 311a of the arm portion 31a. Therefore, in this embodiment, even if backflow water occurs that raises the liquid level from below the valve body 3a to above, for example, the valve body 3a can be positioned at an angle that is likely to be hit by the backflow water from the downstream side of the valve body 3a, and can be operated in a stable closing direction.

In this way, in the second embodiment of the backflow prevention device 1a, under normal circumstances, the valve body 3a basically opens the opening/closing port 20a by forming a gap between it and the valve seat 22a, ensuring a smooth flow of forward flow drainage from upstream to downstream. However, due to the presence of the stopper 24a, the valve body 3a can only open to a position in the vertical direction or closer to the valve seat 22a than the vertical direction, so when backflow water occurs, the valve body 3a can operate to reliably close in response to the impact of the backflow water.

The backflow prevention device 1a of the second embodiment can be used in drainage systems in general, but is particularly suitable for use in sewage systems and sewage applications. In this case, in the backflow prevention device 1a of this embodiment, the valve body 3a keeps the opening 20a open when sewage flows, so that it is possible to effectively prevent filth and other substances contained in the sewage from clogging the valve body 3a.

The above-mentioned functions and effects can also be obtained in the case where the opening/closing port 20 is installed to open diagonally downward in a backflow prevention device 1 of the type in which the valve body is basically closed except when forward flow drainage is flowing, such as in the first embodiment. That is, even in the backflow prevention device 1 of the first embodiment, the stopper 24 (Figure 3b) can limit the rotation angle (rotation range) when the valve body 3 is fully open to a vertical direction or an angle closer to the valve seat portion 22 than the vertical direction, so that the valve body 3 can be positioned at an angle that is likely to receive a force in the closing direction from the backflow water even when backflow water occurs.

As described above, the backflow prevention device 1, 1a of this embodiment has the same configuration, function, and effect of the stoppers 24, 24a, regardless of whether it is a type in which the valve body 3a is basically open or a type in which the valve body 3 is basically closed, and the method of use is also the same.

Therefore, in the second embodiment of the backflow prevention device 1a, if all or part of the stopper 24a (the portion of the stopper 24a above the cut hole 240a) is removed as shown in Figure 3c, the abutment between the abutment portion 311a of the arm portion 31a of the valve body 3a and the stopper 24a (the portion of the stopper 24a above the cut hole 240a) is released, and the valve body 3a can be rotated to a position (angle) farther away from the valve seat portion 22a than in the vertical direction, as in the first embodiment.

On the other hand, in the backflow prevention device 1 of the first embodiment, if the stopper 24 (the portion of the stopper 24 above the cut hole 240) is not removed as shown in Figure 3b, the abutment portion 311 of the arm portion 31 will abut against the stopper 24, so no matter how much the amount of forward flow drainage increases, it is possible to limit the rotation range of the valve body 3 to an angle at which it is likely to be hit by backflow water, and it can be operated to reliably close when backflow water occurs.

Figure 9 shows a perspective view of the backflow prevention device 1a according to the second embodiment attached to a drainage manhole 5a. Note that in Figure 9, only the cylindrical body 50a is shown with a dotted line so that the inside of the drainage manhole 5a can be seen through.

As shown in FIG. 9, the drainage manhole 5a to which the backflow prevention device 1a of the second embodiment is attached has a substantially cylindrical body 50a with a short pipe-shaped inlet 500a and outlet 501a on the side wall, an inverted part 51a that connects the inlet 500a and the outlet 501a and is attached to the lower part of the body 50a, a frame part 52a that has an inspection hatch and is attached to the upper part of the body 50a, and a substantially disk-shaped lid part 53a that is detachably attached to the frame part 52a. In addition, an upstream connecting pipe 54a and a downstream connecting pipe 55a are attached to the inlet 500a and the outlet 501a, respectively, and both connecting pipes 54a and 55a protrude into the inside of the body 50a. In this embodiment, the backflow prevention device 1a is attached by inserting the connecting port 21a into the internal protrusion of the upstream connecting pipe 54a attached to the inlet 500a.

In this embodiment, the drainage manhole 5a is made of concrete material, but it may also be made of a plastic material such as polyvinyl chloride resin, a metal material such as iron, or an appropriate combination of these materials.

In addition, in the drainage manhole 5a, the invert portion 51a and/or the frame portion 52a do not need to be configured as separate parts from the cylindrical body 50a, and may be formed integrally. In this embodiment, the upstream connecting pipe 54a of the inlet 500a opens at a position spaced above the invert portion 51a, and the downstream connecting pipe 55a of the outlet 501a opens in a groove with a U-shaped cross section formed in the invert portion 51a. In addition, in order to provide a drop in the drainage, the outlet 501a and the downstream connecting pipe 55a are positioned so that their respective bottoms are lower than the bottoms of the inlet 500a and the upstream connecting pipe 54a.

In the drainage manhole 5a of this embodiment, the opening/closing port 20a of the valve pipe 2a of the backflow prevention device 1a is opened in a downward diagonal direction by bending the valve pipe 2a. Therefore, under normal circumstances, the forward flow drainage flowing into the drainage manhole 5a from the upstream connecting pipe 54a (inlet 500a) is reliably guided to the invert section 51a, and a gap is formed between the valve body 3a and the valve seat section 22a formed in the opening/closing port 20a, so that even if the amount of forward flow drainage is small, a smooth flow is guaranteed and clogging due to foreign matter is effectively prevented.

On the other hand, in this embodiment, the valve body 3a of the backflow prevention device 1a is restricted in its rotation range (rotation angle) by the stopper 24a and is held at an angle within the vertical plane or closer to the valve seat portion 22a than the vertical plane. Therefore, in the event of an abnormality, even if wastewater flows back from the downstream connecting pipe 55a (outlet 501a) into the drainage manhole 5a, and in addition to the flow from the downstream connecting pipe 55a (outlet 501a) to the upstream connecting pipe 54a (inlet 500a), a flow that raises the liquid level from the invert portion 51a to the upstream connecting pipe 54a (inlet 500a) occurs, the valve body 3a is held at an angle that is likely to be hit by the downstream surface 32a of the valve body 30a against either flow, so it can operate in a stable closing direction.

<Common to the first and second embodiments/Level placement section>
As shown in Figures 4 and 6, in the first embodiment of the backflow prevention device 1 and the second embodiment of the backflow prevention device 1a, a spirit level mounting portion 6, 6a is provided at the top of the valve pipe 2, 2a, which has a plane parallel to the rotation axis (bolts 4, 4a) of the valve body 3, 3a and on which a spirit level can be placed.

The level mount 6, 6a is formed from a flat surface, and the surface is arranged parallel to the rotation axis 4, 4a of the valve body 3, 3a. Therefore, if the level is placed on the level mount 6, 6a sideways so as to be perpendicular to the axis of the valve tube 2, 2a, the display on the level makes it easy to know whether the rotation axis (bolt 4, 4a) of the valve body 3, 3a is arranged horizontally or the rotation trajectory of the valve body 3, 3a is arranged in a vertical plane. As a result, it is possible to easily correct the circumferential angle of the valve tube 2, 2a, and it is possible to prevent poor rotation of the valve body 3, 3a caused by the rotation axis (bolt 4, 4a) of the valve body 3, 3a or its rotation trajectory being arranged at an angle.

In addition, in a backflow prevention device 1 of the type in which the central axis a of the short pipe portion in which the opening/closing port 20 of the valve pipe 2 is basically arranged horizontally, as in the first embodiment, if the level holder 6 is configured to have a plane parallel to the central axis a of the opening/closing port 20, by placing the level vertically on the level holder holder 6, 6a so that it is parallel to the central axis a of the valve pipe 2, it is possible to easily determine from the display of the level whether the valve pipe 2 is arranged horizontally and the opening/closing port 20 is arranged vertically, or whether the opening/closing port 20, 20a is arranged at an angle to the vertical.

As a result, the backflow prevention device 1 of the first embodiment and the backflow prevention device 1a of the second embodiment can be easily centered using a spirit level, and can be accurately and easily attached to the inlet 500, 500a of the drainage manhole 5, 5a described above.

<Common to the first and second embodiments/Marked lines>
As shown in Figures 4 and 6, the backflow prevention device 1 of the first embodiment and the backflow prevention device 1a of the second embodiment have a marked line 7, 7a at the top of the valve pipe 2, 2a that is parallel to the central axis of the opening and closing port 20, 20a of the valve pipe 2, 2a.

Since the marked line 7, 7a is provided at the top of the valve pipe 2, 2a so as to be parallel to the central axis of the opening/closing port 20, 20a, if the backflow prevention device 1, 1a is positioned so that the marked line 7, 7a is located directly above, the valve body 3, 3a will rotate along a vertical plane with its rotation axis positioned horizontally as designed. Therefore, in the first and second embodiments, not only is it possible to easily center the backflow prevention device 1, 1a, and to easily attach it to the inlet 500, 500a of the drainage manhole 5, 5a, for example, but it is also possible to prevent malfunction of the valve body 3, 3a due to accurate attachment.

LIST OF SYMBOLS 1, 1a... Backflow prevention device 2, 2a... Valve pipe 20, 20a... Opening/closing port 21, 21a... Connection port 22, 22a... Valve seat portion 23, 23a... Bearing portion 230, 230a... Column member 231, 231a... Reinforcement rib 232... Shaft hole 24, 24a... First stopper 240, 240a... Cutting hole 241, 241a... Sub-stopper 242, 242a... Inclined surface 25, 25a... Abutment receiving portion 3, 3a... Valve body 30, 30a... Valve body 31, 31a... Arm portion 310, 310a... Shaft hole 311, 311a... First abutment portion 312, 312a... Second abutment portion 32, 32a... Surface 33, 33a: Back side 34, 34a: Packing 4, 4a: Bolt 40, 40a: Nut 5, 5a: Drainage manhole 50, 50a: Cylinder 500, 500a: Inlet 501, 501a: Outlet 51: Bottom 51a: Invert 52, 52a: Frame 53, 53a: Cover 54, 54a: Upstream connecting pipe 55, 55a: Downstream connecting pipe 6, 6a: Level placement section 7, 7a: Marked line a: Central axis of opening and closing port b: Central axis of connection port

Claims (10)

a cylindrical valve pipe having an opening and closing port and a connection port;
a valve seat portion formed at an open end of the valve pipe on the opening/closing side;
a valve body supported rotatably at an upper portion of the valve pipe on the opening/closing side thereof,
A backflow prevention device characterized in that a bearing portion for supporting the valve body is provided on the upper part of the valve pipe, and a stopper that can be removed in whole or in part and that abuts against the valve body to limit the rotation range of the valve body is provided on the bearing portion. 2. The reflux prevention device of claim 1, wherein the stopper has a cutout, and the height of the stopper can be changed by removing a member above the cutout. The backflow prevention device according to claim 2, characterized in that the stopper is formed from a plate-like member thinner than the bearing portion or a removal block partitioned by a cutout groove thinner than the bearing portion. 2. The backflow prevention device according to claim 1, wherein the valve body has an arm portion, and the arm portion abuts against the stopper to limit a rotation range of the valve body. The backflow prevention device according to claim 4, characterized in that the valve pipe has a contact receiving portion at a top portion near the opening and closing port, and the contact receiving portion abuts against the arm portion of the valve body to limit the rotation range of the valve body. The backflow prevention device according to claim 1, characterized in that the top of the valve pipe is provided with a level mount portion that has a flat surface parallel to the rotation axis of the valve body and on which a level can be placed. The backflow prevention device according to claim 1, characterized in that a marking line parallel to the central axis of the opening and closing port is marked on the top of the valve pipe. The backflow prevention device according to claim 1, characterized in that the opening/closing port and the connection port are formed so that the central axis of the opening/closing port and the central axis of the connection port are arranged parallel to each other and eccentrically. The backflow prevention device according to claim 1, characterized in that the valve pipe is curved or bent midway so that the opening and closing port opens diagonally downward when the connection port is arranged to open horizontally. A drain equipped with a backflow prevention device according to any one of claims 1 to 9.

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