JP2023084594A - Back-flow prevention device - Google Patents

Abstract

To provide a back-flow prevention device which can be easily detached in an axial direction even if the inside of a tube body is dirty with filth, etc., and which does not drop off downstream.SOLUTION: A back-flow prevention device attachable to a tube body 1 comprises: a frame body 3 including an opening through which a fluid passes; a watertight part 2 disposed on an outside surface of the frame body 3 and connecting the outside surface of the frame body 3 and the tube body 1 in a watertight manner; a back-flow prevention valve 4 disposed in the opening of the frame body 3 and preventing a back-flow of the fluid from a downstream side to an upstream side; and a grasping part 5 disposed in an axial direction of the back-flow valve 4. The grasping part 5 allows the back-flow prevention device to be attachable to/detachable from the tube body 1 in the axial direction, and the back-flow prevention device includes a drop-off prevention part 7 that prevents the back-flow prevention device from dropping off to the downstream side or being inserted excessively.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backflow prevention device that is arranged on the flow path or at the end of a tubular body for the purpose of preventing backflow.

In a tubular body through which a fluid such as liquid or gas passes, a check valve is arranged on the path or at the end of the tubular body for the purpose of preventing backflow. This is to prevent the fluid from flowing back from downstream to upstream, and when a check valve is placed at the end of the tube, the pressure inside the tube is either positive or negative. It is well known that the pressure in the tube can be adjusted by ventilating the tube when the tube is closed.

The backflow prevention device described in Patent Literature 1 is a backflow prevention valve arranged in a tubular body, and this backflow prevention valve is generally called an umbrella valve. The check valve is composed of a disk-shaped valve body made of an elastic material and a rod-shaped valve shaft provided in the center of the valve body. A joint member that is combined with a valve seat that closes the valve, a fixing part that fixes the valve shaft provided in the center of the pipe, and further unitizes this check valve and connects it to the pipe for maintenance etc. It is described that it is configured so that it can be taken out from the side of the. In this known check valve, the valve body abuts against the valve seat to close the tubular body when there is no fluid pressure such as drainage. When fluid pressure is generated from the upstream side, the pressure causes the valve body to deform due to its own elasticity and separates from the valve seat to open the tubular body, thereby discharging the fluid on the upstream side to the downstream side. When the outflow of the liquid is completed, the valve body returns to its original shape due to its own elasticity, and the valve body again comes into contact with the valve seat, closing the pipe body.
Further, as other known check valves, a valve body composed of a plate-shaped valve body made of a hard material, a hinge part provided on the valve body, and a weight body attached to the valve body via the hinge part, A valve seat is provided in the tubular body and abuts against the valve body to close the inside of the tubular body. This is because the valve body is always in contact with the valve seat due to the action of the weight body and closes the inside of the tube. , discharging waste water from upstream to downstream. When backflow occurs, the valve body maintains a state of contact with the valve seat and closes the inside of the tubular body, so that backflow does not occur.

In addition, the backflow prevention device described in Patent Document 2 constitutes a backflow prevention valve on a tubular body path of a rainwater catch basin buried in the ground. It is sandwiched between and fixed, and the valve body is brought into contact with the valve seat. This well-known check valve includes a substantially disk-shaped valve seat having a shaft hole through which a shaft can be inserted and a circulation hole through which a fluid flows, a shaft inserted through the shaft hole, and one end side of the shaft. and a substantially disk-shaped valve body having a size that covers the flow hole of the valve seat when viewed from the axial direction; a sealing material configured on either the valve seat or the valve body; When the pressure of the tubular body on the downstream side increases, the valve body rises and separates from the valve seat, and the closing of the tubular body is released. Further, when the pressure of the tubular body decreases, the valve body descends due to its own weight, and the sealing material of the valve body comes into contact with the valve seat, closing the inside of the tubular body.

Further, the backflow prevention device described in Patent Document 3 constitutes a backflow prevention valve on a branch pipe, which is a tubular body path of a rainwater catch basin buried in the ground. This backflow prevention device is composed of a bracket attached to the branch pipe and a backflow prevention valve rotatable with respect to the bracket. In the backflow prevention valve of Patent Document 3, a flat plate-shaped valve plate is rotatably attached to the main body, and the valve plate is always seated on the valve seat to close and block the inside of the branch pipe. Further, when drainage occurs, the pressure of the drainage separates the valve plate from the valve seat to open the inside of the branch pipe. With such a configuration, pests such as rats and cockroaches, pests, and foul odors do not flow back from the downstream side of the branch pipe to the main pipe side. In addition, even if the branch pipe of the rainwater catch basin has a drainage gradient, the check valve rotates with respect to the bracket attached to the branch pipe, so the check valve can be properly attached to the branch pipe so that it follows the gradient. It is designed to be

JP 2021-181810 JP 2013-050021 Actual Kaisho 61-084786

The backflow prevention device described in Patent Document 1 is configured to be detachable from a drain pipe for maintenance such as cleaning and repairing the backflow prevention valve. Therefore, it was necessary to configure an inspection port in the tubular body for the attachment and detachment of the check valve. In addition, there is a problem that the side surface of the tubular body is buried and that it cannot be used for buried piping.

Further, in the backflow prevention device described in Patent Document 2, since the valve seat of the backflow prevention device is interposed between the drainage pipes, it is not necessary to disassemble the drainage pipes when performing maintenance on the backflow prevention valve. However, it was difficult to perform maintenance on rainwater catch basins buried in the ground because it was not easy to disassemble the drainage pipes.

In addition, in the backflow prevention device described in Patent Document 3, the backflow prevention valve can be appropriately attached even if the branch pipe, which is a tubular body, has a slope. When removing the prevention device for maintenance, the bracket of the backflow prevention device must be removed by inserting the hand into the narrow main pipe. Therefore, dirt naturally adheres around the bracket of the backflow prevention device, and depending on the case, the dirt sticks and becomes difficult to remove, but the bracket is configured in a flat shape along the inner peripheral surface of the main pipe. Therefore, it was very difficult to put on and take off.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a backflow prevention device that can be easily removed in the axial direction even when the inside of the tubular body is contaminated with dirt or the like.

The backflow prevention device of the present invention comprises a frame 3 that can be attached to a tubular body 1 and has an opening through which fluid passes; A watertight portion 2 that watertightly connects the body 1, a check valve 4 that is provided at the opening of the frame 3 and prevents backflow of fluid from the downstream side to the upstream side, and the check valve and a gripping portion 5 provided in the axial direction of No. 4, wherein the gripping portion 5 allows the backflow prevention device to be detachable from the tubular body 1 in the axial direction, and the backflow prevention device is The backflow preventive device is characterized in that the backflow preventive device is provided with a fall-off preventing portion 7 for preventing falling-off or excessive insertion to the downstream side.

The backflow prevention device of the present invention comprises a frame 3 that can be attached to a tubular body and has an opening through which fluid passes; 1, a check valve 4 provided in the opening of the frame 3 to prevent reverse flow of fluid from the downstream side to the upstream side, and the check valve 4 and a gripping portion 5 provided in the axial direction of the frame 3. and a valve shaft provided in the center of the check valve 4 by watertightly contacting or releasing contact with the valve seat 31 provided in the frame 3. 41 and a fixing portion 6 for fixing the valve shaft 41 provided at the center of the valve seat 31, and the check valve 4 is an umbrella valve.

According to the present invention, since the grip portion 5 of the backflow prevention device is configured in the axial direction of the backflow prevention valve 4, the backflow prevention device can be easily attached and detached in the axial direction. Even if the backflow prevention device adheres to the tubular body 1 due to dirt, it can be easily detached. Since the backflow prevention device is detachable in the axial direction, it is not necessary to provide an inspection port for removing the backflow prevention device, and it can be used for buried type piping.

According to the present invention, by configuring the drop-off prevention portion 7 that prevents drop-off or over-insertion to the downstream side, it is possible to prevent over-insertion and drop-out downstream when attaching to the tubular body 1, and during normal use. Even if excessive pressure is applied to the fluid in the tubular body 1, the backflow prevention device will not come off from the tubular body 1 and flow out downstream. As a result, the tubular body 1 will not be clogged by the backflow prevention device due to the backflow prevention device falling off.

1 is a diagram showing a backflow prevention device according to a first embodiment of the present invention; FIG. (a) is a cross-sectional view taken along line AA' in FIG. (b), (b) is a side view, and (c) is a top view. It is a figure which shows the construction state in 1st Example of this invention. (a) is a cross-sectional view showing a construction state, and (b) is a cross-sectional view showing a maintenance state of the backflow prevention device. Fig. 3 is an enlarged cross-sectional view of the vicinity of the backflow prevention device in Fig. 2(a); (a) is a perspective view showing a backflow prevention device of the present invention. (b) is a cross-sectional perspective view in this figure (a). FIG. 4 is a diagram showing a backflow prevention device according to a second embodiment of the present invention; (a) is a cross-sectional view along line AA' in FIG. (b), and (b) is a side view. FIG. 4 is a diagram showing a construction state in the second embodiment of the present invention; (a) is a cross-sectional view showing a construction state, and (b) is a cross-sectional view showing a maintenance state of the backflow prevention device. FIG. 3 is a diagram showing a backflow prevention device according to a third embodiment of the present invention; (a) is a cross-sectional view along line AA' in FIG. (b), and (b) is a side view. FIG. 10 is a diagram showing a construction state in the third embodiment of the present invention; (a) is a cross-sectional view showing a construction state, and (b) is a cross-sectional view showing a maintenance state of the backflow prevention device. It is a figure which shows the construction state in 4th Example of this invention. (a) is a cross-sectional view showing a construction state, and (b) is a cross-sectional view showing a maintenance state of the backflow prevention device. FIG. 10 is a diagram showing a construction state in another embodiment of the present invention; (a) is a cross-sectional view showing a construction state, and (b) is a cross-sectional view showing a maintenance state of the backflow prevention device.

A first embodiment of the present invention will be described below with reference to the drawings. It should be noted that the explanation given below is for the purpose of facilitating the understanding of the embodiments, and the invention should not be construed as being limited by this.
As shown in FIG. 2, the backflow preventive device of this embodiment is installed in a rainwater catchment 9 which is buried in the ground outside the building and drains rainwater on the rain gutters and road surface to the sewage pipe. The rainwater basin 9 is equipment for precipitating sand, dead leaves, etc. contained in rainwater, temporarily storing rainwater, and regulating the outflow to the sewage pipe. The arrows in the figure indicate the direction of normal flow of wastewater (same below).
The rainwater catch basin 9 is composed of a lid body 8, a main pipe 11, and a branch pipe 12, which will be described below.
The lid body 8 is a detachable lid body 8 arranged on the upper part of the main pipe 11 of the rainwater catch basin 9. The lid body 8 is provided with an opening (not shown) so that rainwater on the ground surface can flow into the rainwater catch basin 9. It is Further, the lid body 8 is provided on the ground G.
The main pipe 11 is the main pipe 11 of the rainwater catch basin 9, and is a portion that temporarily stores rainwater flowing in from the top and rainwater and sewage flowing in from the branch pipes 12 formed on the side. In addition, the bottom of the main pipe 11 can store garbage and dead leaves in rainwater, and the cover 8 is removed periodically to clean the inside of the bottom of the main pipe 11 to remove the accumulated garbage and dead leaves. is configured to allow
The branch pipe 12 is a branch pipe that is branched from the side of the main pipe 11. This is a tubular body 1 through which wastewater from another system flows into the rainwater basin 9 main pipe 11, or a sewage pipe for draining the wastewater in the main pipe 11. It is a tubular body 1 that flows out to. The backflow prevention device of this embodiment is attached to a branch pipe 12 that discharges fluid such as waste water and gas in the main pipe 11 downstream (that is, a sewage pipe).

As shown in FIGS. 1, 3, and 4, the backflow prevention device includes a frame 3, a valve seat 31, a watertight portion 2, a grip portion 5, a backflow prevention valve 4, a valve stem 41, a fixing portion 6, and a drop prevention portion 7. consists of
The frame 3 is detachably attached to the inside of the tubular body 1, and has a shape that matches the shape of the inside of the tubular body 1. In this embodiment, the frame 3 is an annular body configured with an opening extending through it in the axial direction. . In this embodiment, it is detachably arranged in a branch pipe 12 as the tubular body 1 of the rainwater catch basin 9 . The frame 3 also has an opening through which fluid passes, and a check valve 4 for closing the opening. A valve seat 31 on which the check valve 4 is seated is formed at the end of the frame 3 on which the check valve 4 is provided. Also, a grip portion 5 is formed at the other end.
The valve seat 31 is formed on the frame 3, and in this embodiment, is formed on the downstream end in the fluid flow direction.
The watertight portion 2 is formed on the outer peripheral surface of the frame 3, and is made of an elastic material such as rubber or silicon. The outer surface of the watertight portion 2 is in contact with the inner peripheral surface of the branch pipe 12 to connect the outer surface of the frame 3 and the inner surface of the branch pipe 12 in a watertight manner. In this embodiment, the watertight portion 2 is configured vertically in two layers in the axial direction. In addition, watertightness is further enhanced by forming a plurality of (double) watertight portions 2 .
The gripping portion 5 is configured to protrude toward the inflow side in the axial direction of the frame 3, and in this embodiment forms a hole for hooking a finger. In addition, the gripping portion 5 is installed so as to pass through the central axis of the frame 3 , and a fixing portion 6 for fixing the check valve 4 is positioned at the center of the gripping portion 5 .
The fixed portion 6 is formed at the center of the frame 3 , and the valve shaft 41 of the check valve 4 is attached and fixed to the frame 3 by attaching the valve shaft of the check valve to the fixed portion. Although the check valve 4 is elastically deformed by pressure fluctuations in the tubular body 1, the check valve 4 itself does not move even when elastically deformed.
The check valve 4 is provided at the downstream end of the frame 3 in the fluid flow direction, and prevents the fluid from flowing back from the downstream side to the upstream side. The check valve 4 of this embodiment is a disk-shaped plate called an umbrella valve, made of an elastic material such as rubber or silicon, and constitutes a rod-shaped valve shaft 41 provided in the center. The check valve 4 is in watertight contact with the valve seat 31 of the frame 3 to close the opening of the frame 3, or releases the contact to unblock the opening of the frame 3. It is configured.
The valve shaft 41 is a shaft configured at the center of the check valve 4 and arranged coaxially with the central axis of the frame 3 . Further, the valve shaft 41 is fixedly attached to a fixing portion 6 that is constructed over the frame 3 .
In this embodiment, the drop-off preventing portion 7 is a rib that protrudes outward from the side surface of the grip portion 5 as shown in FIGS. 1(b) and 1(c). When the frame body 3 is inserted into the branch pipe 12 as described above, it is engaged with the end portion of the branch pipe 12 or the inner peripheral surface of the main pipe 11 . The anti-dropping part 7 allows the backflow prevention device to be inserted to an appropriate position during insertion (during construction), and prevents the backflow prevention device from falling off due to excessive insertion. In addition, it prevents the backflow prevention device from falling off from the branch pipe 12 when a large amount of waste water is discharged or when the internal pressure of the pipe increases. In this embodiment, the gripping portion 5 is provided with the anti-falling portion 7 , but it is preferable that the anti-falling portion 7 is configured to protrude outward from at least the outer surface of the frame 3 .

When the opening of the frame 3 is closed by the check valve 4, that is, when the valve seat 31 of the frame 3 and the check valve 4 are in contact, the outer surface of the frame 3 and the inner peripheral surface of the branch pipe 12 are watertight. Since the portion 2 is made watertight, the inside of the branch pipe 12 is completely closed. Therefore, fluids such as wastewater and odor on the downstream side do not flow back to the upstream side. In addition, when the pressure of the fluid on the upstream side increases, such as when drainage occurs or when the air pressure in the branch pipe 12 increases, the check valve 4 deforms due to its own elasticity and is separated from the valve seat 31. Then, the blockage of the opening in the frame 3 is released, and fluid such as drainage and air on the upstream side flows downstream. When the pressure on the upstream side weakens, the check valve 4 restores its original shape due to its own elasticity, and the check valve 4 contacts the valve seat 31 of the frame 3 to close the frame 3 . Thereafter, by repeating this process, the normally closed check valve 4 opens when the pressure of the fluid on the upstream side increases, and when the pressure on the upstream side disappears, the check valve 4 comes into contact with the valve seat 31 and seals. Drainage, odors, and insect pests from the downstream side do not flow back to the upstream side.

The backflow prevention device of this embodiment is attached to the branch pipe 12, which is the tubular body 1, by the following procedure.
Remove the lid 8 at the top of the rainwater basin 9, and as shown in FIG. The backflow prevention device is inserted axially from the side to the downstream side, and the backflow prevention device is attached to the branch pipe 12 . In addition, since the anti-backflow device is provided with a drop-off preventing portion 7, when the back-flow preventing device is inserted into the branch pipe 12, as shown in FIG. Installation is completed by inserting until it touches the peripheral surface. Since the anti-backflow device has the drop-off prevention part 7, it is not pushed too far beyond the appropriate position during installation. Also, even if high pressure is generated on the upstream side, the backflow prevention device will not come off.
Since the watertight portion 2 is formed on the outer surface of the frame 3, the watertight portion 2 abuts on the inner periphery of the branch pipe 12, and the inner peripheral surface of the pipe 1 and the outer surface of the frame 3 are well watertight. there is After that, by closing the cover 8 of the rainwater catch basin 9, the attachment of the backflow prevention device to the branch pipe 12 is completed as shown in FIG. 2(a).
When removing the backflow prevention device from the branch pipe 12 for cleaning or maintenance of the backflow prevention device, as shown in FIG. A worker inserts his/her hand into the inside, grasps the grip portion 5 of the backflow prevention device, pulls out the backflow prevention device from the downstream side branch pipe 12 in the axial direction toward the upstream side, and removes the backflow prevention device from the branch pipe 12 . Since the grip part 5 is configured, it is easy to grasp by hand, and a pulling force can be directly applied to the backflow prevention device, so even if dirt adheres around the backflow prevention device, it can be easily removed. Is possible. Depending on the case, a tool or the like may be hooked on the grip portion 5 to remove. After that, the work of removing the backflow prevention device from the branch pipe 12 is completed by the construction worker taking out the backflow prevention device to the outside of the rainwater catch basin 9 . When the maintenance of the backflow prevention device is completed, the backflow prevention device is reinserted into the branch pipe 12 and mounted according to the above-described mounting procedure, thereby completing the mounting to the branch pipe 12 . After that, as shown in FIG. 2(a), the cover 8 is attached to the upper end opening of the rainwater basin, and the work is completed.
In addition, in this embodiment, since the check valve 4 is an umbrella valve, the total length of the check valve in the axial direction can be shortened. can be sufficiently secured for the operation of pulling out or inserting in the axial direction of the branch pipe 12 , that is, in the horizontal direction of the main pipe 11 .

5 and 6 are sectional views of the backflow prevention device of the present invention in the second embodiment. In the drawings and this description, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
As shown in FIG. 6, the backflow prevention device of this embodiment is also provided in the rainwater catch basin 9 .
In this embodiment, a backflow preventive device is detachably attached to the branch pipe 12 that joins the drainage from the rainwater basin, gutter, and sewage basin into the main pipe 11 of the rainwater basin 9 of this embodiment.
As shown in FIG. 5, the backflow prevention device is composed of a frame 3, a valve seat 31, a watertight portion 2, a grip portion 5, a backflow prevention valve 4, a valve shaft 41, a fixing portion 6, and a drop prevention portion 7. Among them, the watertight portion 2, the valve shaft 41, the fixing portion 6, and the drop-out preventing portion 7 are the same as those of the above-described embodiment, and thus the description thereof is omitted.
The frame 3 is detachably attached to the inside of the tubular body 1, and has a shape that matches the shape of the inside of the tubular body 1. In this embodiment, the frame 3 is an annular body configured with an opening extending through it in the axial direction. . In this embodiment, it is arranged in a branch pipe 12 as the tubular body 1 of the rainwater catch basin 9 . The frame 3 also has an opening through which fluid passes, and a check valve 4 for closing the opening. A valve seat 31 on which the check valve 4 is seated is formed at the end of the frame 3 on which the check valve 4 is provided. A grip portion 5 is formed at the end of the frame 3 on the side of the valve seat 31 .
The valve seat 31 is formed on the frame 3, and in this embodiment, is formed on the upstream end in the fluid flow direction.
The gripping portion 5 is configured to protrude toward the outflow side in the axial direction of the frame 3, and in this embodiment forms a hole for hooking a finger. In addition, the gripping portion 5 is installed so as to pass through the center of the frame 3 , and a fixing portion 6 for fixing the check valve 4 is formed in the center of the gripping portion 5 .
The check valve 4 is provided at the downstream end of the frame 3 in the fluid flow direction, and prevents the fluid from flowing back from the downstream side to the upstream side. The check valve 4 of this embodiment is called an umbrella valve, is made of an elastic material such as rubber or silicon, and has a rod-shaped valve shaft 41 provided in the center. The check valve 4 is in watertight contact with the valve seat 31 of the frame 3 to close the opening of the frame 3, or releases the contact to unblock the opening of the frame 3. It is configured.

Since the operation of the check valve 4 is the same as that of the first embodiment, description thereof is omitted.
The backflow prevention device of this embodiment is attached to the branch pipe 12, which is the tubular body 1, by the following procedure.
Remove the cover 8 on the upper part of the rainwater basin 9, and as shown in FIG. The backflow prevention device is attached to the branch pipe 12 by inserting the backflow prevention device in the axial direction toward the upstream side. In addition, since the anti-backflow device has a drop-off preventing portion 7, when the back-flow preventing device is inserted into the branch pipe 12, the drop-off preventing portion 7 should be inserted until it abuts against the end of the branch pipe 12 or the inner peripheral surface of the main pipe 11. Construction will be completed. Since the drop-off prevention part 7 is formed, it is not pushed too much beyond an appropriate position during construction. Also, even if high pressure is generated on the upstream side, the backflow prevention device will not come off.
Since the watertight portion 2 is formed on the outer surface of the frame 3, the watertight portion 2 abuts on the inner periphery of the branch pipe 12, and the inner peripheral surface of the pipe 1 and the outer surface of the frame 3 are well watertight. there is After that, as shown in FIG. 6(a), the attachment of the backflow prevention device to the branch pipe 12 is completed by closing the cover 8 of the rainwater catch basin 9. As shown in FIG.
When removing the backflow prevention device from the branch pipe 12 for cleaning or maintenance of the backflow prevention device, as shown in FIG. A worker inserts his or her hand into the inside, grasps the grip part 5 of the backflow prevention device, and pulls out the backflow prevention device from the upstream side branch pipe 12 in the axial direction toward the downstream side, thereby removing the backflow prevention device from the branch pipe 12 . Since the grip part 5 is configured, it is easy to grasp by hand, and a pulling force can be directly applied to the backflow prevention device, so even if dirt adheres around the backflow prevention device, it can be easily removed. Is possible. Depending on the case, a tool or the like may be hooked on the grip portion 5 to remove. After that, the work of removing the backflow prevention device from the branch pipe 12 is completed by the construction worker taking out the backflow prevention device to the outside of the rainwater catch basin 9 . When the maintenance of the backflow prevention device is completed, the backflow prevention device is reinserted into the branch pipe 12 and mounted according to the above-described mounting procedure, thereby completing the mounting to the branch pipe 12 . After that, as shown in FIG. 6(a), the cover 8 is attached to the upper end opening of the rainwater basin, and the work is completed.
In addition, in this embodiment, since the check valve 4 is an umbrella valve, the total length of the check valve in the axial direction can be shortened. can be sufficiently secured for the operation of pulling out or inserting in the axial direction of the branch pipe 12 , that is, in the horizontal direction of the main pipe 11 .

7 and 8 are cross-sectional views of a backflow prevention device of the present invention in a third embodiment. In the drawings and this description, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
As shown in FIG. 8, the backflow prevention device of this embodiment is also provided in the rainwater catch basin 9. As shown in FIG.
In addition, the backflow prevention device of this embodiment is detachably attached to the upstream end of the main pipe 11 of the rainwater basin 9, and rainwater on the ground is drained downstream through the lid, and the inside of the rainwater basin 9 It prevents odors and pests from flowing back to the ground. Further, the backflow prevention device attached to the downstream branch pipe 12 in this embodiment has the same configuration as that of the first embodiment, so the description thereof is omitted.
As shown in FIG. 7, the backflow prevention device comprises a frame 3, a valve seat 31, a watertight portion 2, a grip portion 5, a backflow prevention valve 4, a valve stem 41, and a fixed portion 6. Since the valve seat 31, the check valve 4, the valve shaft 41, and the fixed portion 6 are the same as those of the above embodiment, description thereof will be omitted.
The watertight portion 2 is formed on the outer peripheral surface of the frame 3, and is made of an elastic material such as rubber or silicon. Since the outer surface of the watertight portion 2 is in contact with the inner peripheral surface of the main pipe 11, the outer surface of the frame 3 and the inner surface of the main pipe 11 are watertightly connected. In this embodiment, the watertight portion 2 is composed of an O-ring, which is a ring-shaped annular body.
The gripping portion 5 is configured to protrude toward the outflow side of the frame 3 in the axial direction, and is installed so as to pass through the center of the frame 3 . is configured.

Since the operation of the check valve 4 is the same as that of the first embodiment, description thereof is omitted.
The backflow prevention device attached to the main pipe 11 of this embodiment is attached to the branch pipe 12, which is the tubular body 1, by the following procedure.
Remove the lid 8 on the top of the rainwater basin 9, and as shown in FIG. The backflow prevention device is attached to the end of the main pipe 11 by inserting the backflow prevention device in the axial direction from the upstream side to the downstream side of the main pipe as shown in (a). Further, in the present embodiment, the backflow prevention device does not include the drop-off preventing portion 7, but the drop-off preventing portion 7 may be provided. When the anti-falling part 7 is configured, when the backflow prevention device is inserted into the main pipe 11, the anti-falling part 7 is inserted until it comes into contact with the end of the main pipe 11 or the ground G, thereby completing the construction. When the drop-off prevention part 7 is configured, it is not pushed too much beyond an appropriate position during construction. Also, even if high pressure is generated on the upstream side, the backflow prevention device will not come off.
Since the watertight portion 2 is formed on the outer surface of the frame 3, the watertight portion 2 abuts on the inner periphery of the main pipe 11, and the inner peripheral surface of the pipe 1 and the outer surface of the frame 3 are well watertight. there is After that, as shown in FIG. 8(a), the attachment of the backflow prevention device to the main pipe 11 is completed by closing the cover 8 of the rainwater catch basin 9. As shown in FIG.
Also, when removing the backflow prevention device from the main pipe 11 for cleaning or maintenance of the backflow prevention device, as shown in FIG. A worker inserts his or her hand into the grip part 5 and pulls out the backflow prevention device from above the main pipe 11 toward the upstream side in the axial direction to remove the backflow prevention device from the main pipe 11 . Since the grip part 5 is configured, it is easy to grasp by hand, and a pulling force can be directly applied to the backflow prevention device, so even if dirt adheres around the backflow prevention device, it can be easily removed. Is possible. Depending on the case, a tool or the like may be hooked on the grip portion 5 to remove. The work of removing the backflow prevention device from the main pipe 11 is completed as shown in FIG.
Further, as shown in FIG. 8(b), cleaning and maintenance of the rainwater basin 9 and the backflow prevention device attached to the branch pipe 12 of the present embodiment can be performed with the backflow prevention device removed from the main pipe 11. It is possible to perform the maintenance (see FIGS. 8(a) and (b)). The backflow prevention device for the branch pipe 12 for which maintenance has been completed is reattached to the branch pipe 12 by the installer.
When the maintenance of the backflow prevention device attached to the main pipe 11 is completed, the maintenance work on the main pipe 11 is completed by reinserting the backflow prevention device attached to the main pipe 11 into the main pipe 11 according to the above-described mounting procedure. After that, as shown in FIG. 8(a), the cover 8 is attached to the upper end opening of the rainwater catch basin 9, and the work is completed.

FIG. 9 is a cross-sectional view of a backflow prevention device of the present invention in a fourth embodiment. In the drawings and this description, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
As shown in FIG. 9, the backflow prevention device of this embodiment is also provided in the rainwater catch basin 9. As shown in FIG.
In this embodiment, a branch pipe 12 for draining water from the rain gutter is provided upstream of the rainwater catch basin 9, so that water from the rain gutter flows into the main pipe 11 of the rainwater catch basin 9. As shown in FIG. An upper end of the branch pipe 12 communicates with the ground G to form an opening, and a lid body 8 is attached to the opening. A backflow prevention device is detachably attached to the branch pipe 12 . Further, the backflow prevention device detachably attached to the downstream branch pipe 12 in this embodiment has the same configuration as that of the first embodiment, so the description thereof will be omitted.
As in the first embodiment, the backflow prevention device is composed of a frame 3, a valve seat 31, a watertight portion 2, a grip portion 5, a backflow prevention valve 4, a valve stem 41, and a fixed portion 6. Since the configuration is the same as that of the first embodiment, the description is omitted.

Since the operation of the check valve 4 is the same as that of the first embodiment, description thereof is omitted.
The backflow prevention device attached to the main pipe 11 of this embodiment is attached to the branch pipe 12, which is the tubular body 1, by the following procedure.
Remove the lid 8 at the upper end of the branch pipe 12 constructed on the ground G, and as shown in FIG. The backflow prevention device is attached to the branch pipe 12 by inserting the backflow prevention device axially upstream from the . Further, in the present embodiment, the backflow prevention device does not include the drop-off preventing portion 7, but the drop-off preventing portion 7 may be provided. When the anti-falling portion 7 is configured, when the backflow prevention device is inserted into the branch pipe 12, the work is completed by inserting the anti-falling portion 7 until it contacts the end of the branch pipe 12 or the ground G. When the drop-off prevention part 7 is configured, it is not pushed too much beyond an appropriate position during construction. Also, the backflow prevention device does not come off.
Since the watertight portion 2 is formed on the outer surface of the frame 3, the watertight portion 2 abuts on the inner periphery of the main pipe 11, and the inner peripheral surface of the pipe 1 and the outer surface of the frame 3 are well watertight. there is After that, as shown in FIG. 9(a), the attachment of the backflow prevention device to the main pipe 11 is completed by closing the cover 8 of the rainwater catch basin 9. As shown in FIG.
When removing the backflow prevention device from the branch pipe 12 for cleaning or maintenance of the backflow prevention device, as shown in FIG. 12, the worker inserts his/her hand from above 12, grasps the grip portion 5 of the backflow prevention device, and pulls out the backflow prevention device in the axial direction upstream of the branch pipe 12, thereby removing the backflow prevention device from the branch pipe 12. At this time, since the backflow prevention device is provided with a grip portion 5, it is easy to grasp by hand, and a pulling force can be applied directly to the backflow prevention device, so that dirt adheres around the backflow prevention device. Even if it is, it can be easily removed. Depending on the case, a tool or the like may be hooked on the grip portion 5 to remove. After that, the work of removing the backflow prevention device from the branch pipe 12 is completed by the construction worker taking out the backflow prevention device to the outside of the rainwater catch basin 9 . When the maintenance of the backflow prevention device is completed, the backflow prevention device is reinserted into the branch pipe 12 and mounted according to the above-described mounting procedure, thereby completing the mounting to the branch pipe 12 . Thereafter, as shown in FIG. 9(a), the cover 8 is attached to the upper end opening of the branch pipe 12, and the work is completed.

Although the embodiments of the present invention have been described above, the present invention is not limited to the shapes of the respective embodiments, and modifications may be made as appropriate without departing from the scope of the invention. For example, in the above embodiment, the tubular body 1 was the main pipe 11 or the branch pipe 12 in the rainwater catch basin 9, but it may be installed in the drain pipe of a bathtub, washstand, kitchen, etc., or in a drain trap.
In addition, the backflow prevention device in the above embodiment is a backflow prevention valve that prevents the backflow of fluid from the downstream side to the upstream side. When the valve deforms and releases downstream air to the upstream side, it is possible to adjust the downstream air pressure to an appropriate pressure. A tube internal pressure regulating valve may be used in which the prevention valve is deformed to suck the air on the upstream side to the downstream side and adjust the air pressure on the downstream side to a proper pressure.
In the backflow prevention device of the above embodiment, although the branch pipe 12 has a drainage gradient, it is constructed substantially horizontally. As shown in FIG. The main pipe 11 may be provided with a slope equal to or greater than the specified drainage slope. In this case, compared to when the branch pipe 12 is substantially horizontal, the diameter of the main pipe 11 can be made smaller.

1 Pipe 11 Main pipe 12 Branch pipe 2 Watertight portion 3 Frame 31 Valve seat 4 Non-return valve 41 Valve shaft 5 Grip portion 6 Fixing portion 7 Falling prevention portion 7
8 Lid 9 Rainwater basin G Ground

Claims (5)

a frame 3 attachable to the tubular body 1 and provided with openings through which fluid passes;
a watertight portion 2 arranged on the outer surface of the frame 3 to watertightly connect the outer surface of the frame 3 and the tubular body 1;
A check valve 4 provided at the opening of the frame 3 to prevent reverse flow of fluid from the downstream side to the upstream side;
a gripping portion 5 provided in the axial direction of the check valve 4;
A backflow prevention device comprising:
The backflow prevention device can be attached and detached from the tubular body 1 in the axial direction by the grip portion 5,
1. A backflow prevention device, characterized in that the backflow prevention device is provided with a dropout prevention portion 7 for preventing the backflow prevention device from coming off or being overinserted downstream. the check valve 4 configured to close or release the opening of the frame 3 by watertightly abutting or releasing the abutment against a valve seat 31 provided in the frame 3;
a valve shaft provided in the center of the check valve 4;
a fixing portion 6 for fixing the valve shaft 41 provided in the center of the valve seat 31;
The backflow prevention device according to claim 1, characterized in that it is an umbrella valve consisting of: a frame 3 attachable to the tube and provided with openings through which the fluid passes;
a watertight portion 2 arranged on the outer surface of the frame 3 to watertightly connect the outer surface of the frame 3 and the tubular body 1;
A check valve 4 provided at the opening of the frame 3 to prevent reverse flow of fluid from the downstream side to the upstream side;
a gripping portion 5 provided in the axial direction of the check valve 4;
A backflow prevention device comprising:
The backflow prevention device can be attached and detached from the tubular body 1 in the axial direction by the grip portion 5,
the check valve 4 configured to block or unblock the opening of the frame 3;
a valve shaft 41 provided in the center of the check valve 4 in watertight contact with or released from the valve seat 31 provided in the frame 3;
a fixing portion 6 for fixing the valve shaft 41 provided in the center of the valve seat 31;
A backflow prevention device, wherein an umbrella valve consisting of is used as the backflow prevention valve 4. The backflow prevention device according to any one of claims 1 to 3, characterized in that the backflow prevention device is arranged in a tubular body (1) buried in the ground. The backflow prevention device according to any one of claims 1 to 4, characterized in that the backflow prevention device is arranged in the main pipe 11 of the tubular body 1 or in the branch pipe 12 formed by branching the main pipe 11. backflow prevention device.

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