JP2935185B1 - Automatic rubber wedging device with overpressure prevention mechanism - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To prevent over pressure of a bag-shaped weir body, automatically fall down due to rising water level of a river, and then re-establish it, there is no need to replenish the liquid medium again, and keep the whole apparatus low. The present invention provides an automatic fall / fall device for a rubber weir provided with an overpressure prevention mechanism. SOLUTION: A blower 3, a supply / exhaust pipe connecting the blower and the bag-shaped weir 2 and provided with an intake valve 10 and an exhaust valve 12 in the middle, and disposed above the water surface of the river to open the upper side. A water tank including an upper water tank 5 and a lower water tank 6, a communication pipe 13 provided between a bottom plate side of the upper water tank and a bottom plate side of the lower water tank, and a U-shaped communication pipe communicating the communication pipe and the supply / exhaust pipe. 19, an air pipe 14 installed between the blower and the lower water tank, and a float valve provided on a branch pipe of the air pipe and opened and closed by a float floating on the surface of the river,
Opening and closing the blower and each valve can raise and lower the bag-shaped dam, and also can automatically prevent overpressure and fall of the bag-shaped dam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic fall / fall device for a rubber weir for raising and lowering a bag-shaped weir, and more particularly to an automatic fall / fall device for a rubber weir having an overpressure prevention mechanism capable of preventing overpressure and automatic undulation. About.

[0002]

2. Description of the Related Art There are various known techniques relating to rubber dams. For example, Japanese Utility Model Publication No. Sho 61-2194,
JP-A-3-76919, Patent No. 25552474
(JP-A-63-219717). These have characteristics of preventing overpressure of the bag-shaped dam body and the undulating structure, respectively, and generally have the structure shown in FIGS. 16 and 17. The automatic falling device of the rubber weir provided with the overpressure prevention mechanism shown in FIG.
and a supply / exhaust pipe 9a having an exhaust valve 12a and a blower 3a and connecting the blower 3a to the bag-like dam 2a of a flexible film.
U-shaped tube 2 connected at one end and open at the other end in the middle of a
7 and a float valve 17a, etc., which is connected to a bent portion 28 below the U-shaped pipe 27 and is opened and closed by a float 7a floating on the water surface 18 of the river. A liquid medium 29 having a water head pressure H1 is injected into the opening side of the U-shaped tube 27, and the air supply pressure of the air supplied from the blower 3a to make the bag-shaped weir 2a a predetermined standing shape. Balanced. Of course, in this state, the float valve 17a is closed and the air supply valve 10a is open. Head pressure H
Numeral 1 corresponds to an air supply pressure required to maintain the bag-shaped weir 2a in a predetermined undulating shape, and has an appropriate value in consideration of a change in the internal pressure of the bag-shaped weir 2a. When the pressure of the bag-shaped weir 2a exceeds the head pressure H1, the air in the bag-shaped weir 2a flows out through the U-shaped tube 27 against the liquid medium 29,
At this time, the liquid medium 29 also gushes at a stretch, and as a result, there is a problem that the bag-shaped weir 2a falls down. Also, when the water surface 18 of the river exceeds a predetermined height, the flow starts.
When the gate 7a rises, the float valve 17a is opened and the bag-like dam 2a falls down. However, in order to lower the water surface 18 of the river and raise the bag-like dam 2a again, the liquid medium 29 is supplied again. I had to.

[0003] The automatic falling device of the rubber weir provided with the overpressure prevention mechanism shown in FIG. 17 is a U-shaped pipe 27 of the automatic falling device of the rubber weir provided with the overpressure prevention mechanism shown in FIG. Instead, it has a water-sealed tube 30 into which a liquid medium is charged by an appropriate level height H1. The overpressure is prevented by the air in the bag-shaped dam 2a flowing out through the water seal tube 30. In this case, only the air flows out without the liquid medium flowing out, so that the water head pressure H1 is maintained. However, when the water surface 18 of the river exceeds a predetermined height, the float 7a
Rises to open the float valve 17a,
When the liquid medium flows out, the bag-like dam 2a falls down, but in order to lower the water surface 18 of the river and raise the bag-like dam 2a again, the liquid medium 29 has to be supplied again.

In both cases, the liquid medium 29 must be drained in order to automatically fall down. For that purpose, the float valve 17a must be arranged below the head pressure H1, that is, below the liquid medium 29. In addition, it is necessary to set the position higher than the flood water level of the river. As a result, there is a problem that the height of the entire apparatus is increased, the height of the hut is increased, and the cost is increased.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims to prevent overpressure of a bag-like dam.
In addition, even when the sack-shaped weir body automatically falls due to rising water level of the river and then stands up again, it is not necessary to replenish the liquid medium again, and it is not necessary to position the float valve below the liquid medium. Therefore, it is an object of the present invention to provide an automatic falling device of a rubber weir provided with an overpressure prevention mechanism which can reduce the height of the entire device and is advantageous in cost.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above objects, the present invention provides a flexible membrane bag-like weir body that allows air to flow into and out of the bag-like weir body to expand and contract. An automatic fall device for a rubber weir provided with a mechanism for preventing overpressure of the bag-like weir, wherein the automatic fall device for the rubber weir connects the blower, the blower and the bag-like weir, and A water supply / exhaust pipe provided with an air supply valve and an exhaust valve, an upper water tank disposed at least above the water surface of the river and opening the upper side, and a lower water tank disposed below the water tank, and a bottom plate of the upper water tank A communication pipe installed between the side and the bottom plate side of the lower water tank, a U-shaped communication pipe communicating with the communication pipe and the supply / exhaust pipe and having a bent portion below the bottom plate of the lower water tank,
An air pipe installed between the blower and the lower water tank, and a float valve provided on a branch pipe of the air pipe and opened and closed by a float floating on the water surface of the river, wherein the blower and each valve The automatic weir device of the rubber weir provided with an overpressure prevention mechanism capable of opening and closing the bag-shaped weir to raise and lower the bag-like dam and automatically performing overpressure prevention and falling of the bag-shaped weir It constitutes.

[0007] An upper water tank and a lower water tank of the water tank are defined mutually and connected by the communication pipe.
The U-shaped communication pipe is connected to the communication pipe. Further, a drooping pipe communicating with the inside of the upper water tank is connected to a bottom plate of the upper water tank of the water tank, and a lower end of the drooping pipe is opened to the bottom plate side of the lower water tank, and one end of the U-shaped communication pipe is connected to the lower pipe. It is characterized in that it penetrates into the hanging tube and is opened. Further, a plurality of sets of the bag-shaped weir body, the supply / exhaust pipe engaging with the weir-shaped weir body, and the U-shaped communication pipe are provided.

At first, the bag-shaped weir in the laid-down state is operated by operating each valve to operate the blower, and the bag-shaped weir is prepared to rise by supplying a supply pressure lower than a predetermined pressure at the time of predetermined water storage. In the start state, the blower is stopped after the liquid medium reservoir having a predetermined water height is formed in the upper water tank and the U-shaped communication pipe,
Preparation for the standing operation is completed. When the blower is operated in this state, air enters the bag-shaped weir, and when the water pressure exceeds a predetermined head pressure H1, the air flows through the lower water tank into the upper water tank, so that the air is always constant regardless of the supply pressure of the blower. The pressure H1 acts on the sack-shaped weir body, and the sack-shaped weir body forms a predetermined standing state and a predetermined weir height is secured. In this state, the blower is stopped and each valve is closed to make a steady state. In this state, if the pressure inside the bag-shaped dam is increased due to solar heat or the like and the pressure is slightly increased, the head pressure H1 increases. However, if the degree of the overpressure exceeds the water head pressure H2, the air inside the bag-shaped dam is reduced. Escapes into the atmosphere via the U-shaped communication pipe and the upper water tank, so that the overpressure in the bag-shaped weir is maintained within the maximum head pressure H2. Also, when the water level of the river rises to some extent, the float operates,
The float valve is opened, the liquid medium in the upper water tank flows into the lower water tank and remains in the U-shaped communication pipe, and has a water head pressure H3. However, since the air pressure in the bag-shaped weir is higher than that, The liquid medium in the U-shaped communication pipe is jetted out, and the bag-shaped dam body falls down at a stretch.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a rubber dam automatic falling device provided with an overpressure prevention mechanism according to an embodiment of the present invention. FIG. 1 shows an entire configuration of an automatic falling device of a rubber weir provided with an overpressure prevention mechanism of the present invention. An automatic falling device 1 for a rubber weir having an overpressure prevention mechanism is roughly classified into a bag-like weir 2
, A blower 3, a water tank 4 including an upper water tank 5 and a lower water tank 6, a float 7, various pipes, valves and the like.

The bag-shaped dam 2 is formed of a bag formed of a flexible film and fixed to the dam bottom 21. In addition, it has a structure in which air is introduced and expanded and contracted. When the pressurized air is not introduced, the bag-shaped weir body 2 is in a lying state,
It stands up when the compressed air is introduced. The volume of the bag-shaped weir body 2 increases due to the pressure of the introduced compressed air, and the weir height increases accordingly. Therefore, a gate having a desired weir height is formed by adjusting the pressure and amount of air introduced into the bag-shaped weir body 2.

The upper water tank 5 of the water tank 4 is composed of a tank having an appropriate volume and an upper side opened. In this embodiment, a bottom plate 8 is formed. Below the upper water tank 5, a lower water tank 6 is tightly connected by a bottom plate 8 and is defined.

An air supply / exhaust pipe 9 is provided between the bag-shaped weir 2 and the blower 3, and an air supply valve 10 is provided between the pipes. An exhaust valve 12 is provided on the branch pipe 11 of the supply / exhaust pipe 9. On the other hand, the bottom surfaces of the upper water tank 5 and the lower water tank 6 are connected by a communication pipe 13. An air pipe 14, which is one of the air supply pipes branched from the air supply / exhaust pipe 9 between the air supply valve 10 and the blower 3, is connected to the upper side of the lower water tank 6, and a pumping valve is provided at an intermediate portion thereof. 15 are interposed.
A float valve 17 is provided on the branch pipe 16 of the air pipe 14, and the float valve 17 is connected to the float 7. The float 7 floats above the water surface 18 of the river.

The U-shaped communication pipe 19 has one end connected to the communication pipe 13 and the other end connected to the supply / exhaust pipe 9.

There are also various known techniques for the structure around the float 7 and the float valve 17, for example, the structure disclosed in Japanese Patent Publication No. 57-34407. This product has a bell crank lever and has a structure similar to that schematically shown in FIG. Float 7a
The latch 22 is disengaged with the rise of the weight, and the float valve 17a is operated by the weight 23. The float and the float valve structure have excellent features, of course, but are complicated by the opening and holding mechanism by the latch 22. On the other hand, as the float structure employed in the present invention, the float structure shown in FIG.
The following are used. FIG. 11 shows the operation of the float valve 17 by introducing the upstream water into the bucket 24 by the water pipe 25. The one shown in FIGS. 12 and 13 operates the bucket 24 using the principle of the siphon 26. Is what you do. 12 and 13 can prevent water from flowing into the operation room when the water level is high. Further, the float structure has an open holding mechanism. However, the open holding mechanism is not particularly required, and the float valve operation by the float may be a method of simply connecting the float and the lever of the float valve.

Next, the operation of raising and lowering the bag-like dam body 2 by the rubber dam automatic falling device of the present invention will be described with reference to FIGS. FIG. 2 shows the state of each part at the start of the preparation of the standing operation of the bag-shaped weir. The liquid medium 29 is stored in the lower water tank 6, and the liquid medium 29 is not introduced into the upper water tank 5 or the U-shaped communication pipe 19. Air supply valve 10 and flow
When the blower 3 is operated while the exhaust valve 12 and the pumping valve 15 are opened, the liquid medium 29 in the lower water tank 6 is pressed by air pressure as shown in FIG. It moves into the upper water tank 5 and also into the U-shaped communication pipe 19. Since the air in the bag-shaped weir 2 is exhausted from the exhaust valve 12, the bag-shaped weir 2 is in a falling state. FIG. 3 shows a state in which the preparation for the upright operation of the bag-like dam body 2 is completed, the exhaust valve 12 is closed, the air supply valve 10 is opened, and the blower 3 is once stopped.

FIG. 4 shows a state in which the bag-shaped dam 2 is raised. When the blower 3 is operated in the state of FIG. 3, the pouch-shaped weir 2 provided on the weir bottom 21 by the air pressure of the blower 3.
Rises, but when this air pressure exceeds the water head pressure H1,
The air passes through the lower water tank 6 and the communication pipe 13 to the upper water tank 5.
Since the air passes through the inside of the liquid medium 29 and escapes into the atmosphere, the air pressure of the blower 3 acting on the bag-shaped weir 2 does not exceed the water head pressure H1. In this way, the bag-shaped weir body 2 can be erected in a predetermined upright state, and the weir height can be set to a predetermined position. Thereafter, all the valves, that is, the supply valve 10 and the exhaust valve 1
By closing the pump 2 and the pumping valve 15 and stopping the blower 3, the bag-shaped weir body 2 maintains the standing state while maintaining the water head pressure H1. Of course, the float valve 17 is closed unless the water level 18 of the river rises. FIG. 5 shows a state of each part when the bag-shaped weir body 2 is in a stable upright state.

FIG. 6 shows an overpressure preventing action when the pressure in the bag-shaped weir body 2 rises abnormally. When the pressure in the bag-shaped weir 2 rises due to the influence of the outside temperature or the like, the overpressure acts on the U-shaped communication pipe 19 to push down the liquid medium 29 in the U-shaped communication pipe 19, and the water head pressure increases from H1. H2.
When the water head pressure becomes equal to or higher than H2, the air in the bag-shaped weir body 2 passes through the bent portion 20 of the U-shaped communication pipe 19, enters the upper water tank 5 through the communication pipe 13, and becomes bubbles to the atmosphere. escape. As a result, the overpressure in the bag-shaped weir body 2 becomes the maximum head pressure H2
Nothing more. As described above, the overpressure prevention is automatically performed, and the bag-shaped weir 2 does not fall down even if the overpressure state occurs.

In the state shown in FIG. 6, the overpressure is automatically prevented, but when urging the bag-like weir body 2 urgently, the exhaust valve 12 is manually or mechanically opened as shown in FIG. By doing so, the over-pressure air is released from the exhaust valve 12 to the atmosphere side, and the bag-shaped weir 2 can be made to fall.

Next, referring to FIG. 8, a description will be given of the operation of each part when the bag-shaped weir 2 standing upright in a normal state automatically falls down due to the rise of the water surface 18 of the river. As shown, the float 7 rises due to the rise of the water surface 18 of the river,
Thereby, the float valve 17 is opened. As a result, the air in the lower water tank 6, which has maintained the pressure of the water head pressure H1, escapes from the float valve 17 and is depressurized, so that the liquid medium 29 in the upper water tank 5 passes through the communication pipe 13 into the lower water tank 6. Go to At this time, the liquid medium 29 also exists in the U-shaped communication pipe 19 at the same water level as the lower water tank 6. However, the air pressure in the bag-shaped weir 2 is maintained at the water head pressure H1 and is higher than the water head pressure H3 when the liquid medium 29 moves into the lower water tank 6, so that the air pressure remains in the U-shaped communication pipe 19. The liquid medium 29 is blown up at once, and the air in the bag-shaped weir 2 is supplied to the supply / exhaust pipe 9, the U-shaped communication pipe 19, and the communication pipe 1.
It is possible to escape to the atmosphere via the empty water tank 3 and the emptied upper water tank 5 and to make the bag-shaped weir 2 fall down.

FIG. 9 shows the operation of each part when the bag-like weir 2 is returned to the upright state again when the bag-like weir 2 is urgently or manually fallen down by the method shown in FIG. , Showing the action. In this case, each of the valves, that is, the supply valve 10, the pumping valve 15, and the float valve 17 are closed, only the exhaust valve 12 is open, and the liquid medium 29 also remains in the upper water tank 5. Therefore, as an operation, the exhaust valve 12 is closed,
It is only necessary to start the operation of the blower 3 and open the air supply valve 10. By this operation, the pressure in the U-shaped communication pipe 19 and the inside of the bag-like weir 2 rises, and the bag-like weir 2 shifts from the lying state to the upright state, and can be returned to the normal state.

FIG. 10 is a configuration diagram of another embodiment of the automatic falling device of the rubber weir provided with the overpressure prevention mechanism of the present invention. As shown in the figure, in the rubber dam automatic falling device 1a having the overpressure prevention mechanism of the present embodiment, the upper water tank 5a and the lower water tank 6a
The communication pipe 13 and the U-shaped communication pipe 19a for communicating with the water tank
Are different from those described above, but the structures and arrangements of the other components are the same, and redundant description will be omitted. A hanging pipe 31 is connected to the bottom surface of the upper water tank 5a. The hanging pipe 31 has an open lower end near the bottom plate 32 of the lower water tank 6a. On the other hand, the communication pipe 13 is eliminated, and the other end of the U-shaped connection pipe 19a is connected to the supply / exhaust pipe 9 and one end of the U-shaped connection pipe 19a passes through the bottom plate 32 of the lower water tank 6a and enters the inside from the lower end of the hanging pipe 31. Then open the upper end. With the above-described structure, automatic undulation, automatic overpressure prevention, and the like are performed in substantially the same manner as in the embodiment of the automatic fall device for a rubber weir provided with the overpressure prevention mechanism.

Although the above-mentioned automatic falling device of the rubber weir provided with the overpressure prevention mechanism is for a single gate, the present invention is also applicable to the case of a multi-gate. FIG.
Fig. 1 shows an apparatus structure in a case where the bag-shaped dams 2b and 2c of two gates are automatically raised / lowered, overpressure-prevented, and automatically laid down by a rubber dam automatic fall / fall device 1b having a single overpressure prevention mechanism. It is. Of course, not only the two gates, but also the simultaneous operation of the bag-shaped weirs of a plurality of gates is performed by an automatic fall-down device of a rubber weir provided with an overpressure prevention mechanism having substantially the same structure. The description is omitted because it is the same as above.

If a plurality of gates are to be automatically adjusted in a conventional manner, an independent device is required for each gate, and an overpressure prevention device and a falling device are required. For this reason, the operating time tends to be different for each gate, and there is a problem that the river water level rapidly drops due to the gate that has fallen earlier, and other gates cannot fall down. Japanese Patent Application Laid-Open No. Hei 8-189022 discloses a known technique relating to a multi-row undulating weir.
However, this method has a problem that the device structure is complicated and the equipment cost is large. The present invention solves the above problems. Structurally, as shown in FIG. 15, two supply / exhaust pipes 9b and 9c are connected to the blower 3 side, and are connected to the bag-shaped dams 2b and 2c, respectively. Also,
Each of the supply / exhaust pipes 9b, 9c has a U-shaped communication pipe 19b, 1
9c, which are connected to the same place of the common communication pipe 13. With the above configuration, two bag-shaped dams 2
b and 2c can be automatically raised and lowered simultaneously.

As is apparent from the above description, the automatic falling device of the rubber weir provided with the overpressure prevention mechanism of the present invention provides a relatively low pressure (approximately 0.7 times the set pressure) supply pressure during the blower operation. Thus, the bag-shaped weir body is erected by the supply of air at the set pressure, and a substantially constant erected state can be maintained even when the blower pressure fluctuates. In addition, the overpressure preventing function automatically operates to prevent damage to the sack-shaped dam, and to maintain a constant standing upright at all times. Also, the float valve may be of a small diameter because it only needs to discharge air, can be operated with a small operating force, and may be small in overall structure.

[0025]

According to the automatic falling device of the rubber weir provided with the overpressure prevention mechanism of the present invention, the following effects can be obtained. (1) Even when excessive air pressure acts on the sack-shaped dam, it can automatically maintain a substantially constant pressure, preventing damage to the sac-shaped dam and causing the sac-shaped dam to fall down. Absent. (2) The liquid medium held in the upper and lower water tanks does not flow out to the outside at the time of automatic overfall prevention due to excessive pressure acting on the bag-shaped weir body and the rising of the water surface of the river, without flowing out to the outside. Constant, no need to replenish. (3) Since the mounting position of the float valve is not limited to the lower part of the liquid medium but can be installed at a high place, the height of the entire apparatus can be reduced, and the equipment cost can be reduced. (4) Since the float valve only needs to discharge gas, it is possible to use a small valve and reduce the equipment cost.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a rubber dam automatic falling device provided with an overpressure prevention mechanism of the present invention.

FIG. 2 is an explanatory diagram showing a state of each part at the time of starting preparation for a standing operation of a bag-like dam body of the automatic falling device for a rubber dam provided with an overpressure prevention mechanism in FIG.

FIG. 3 is an explanatory diagram showing the state of each part when the preparation of the standing operation of the bag-shaped weir body of the automatic fall device for rubber weirs having the overpressure prevention mechanism in FIG. 1 is completed.

FIG. 4 is an explanatory view showing the state of each part when the bag-like dam body of the automatic fall device for rubber dam provided with the overpressure prevention mechanism in FIG. 1 is erected.

FIG. 5 is an explanatory view showing the state of each part when the upright completion of the bag-shaped weir body of the automatic fall device for rubber weirs provided with the overpressure prevention mechanism in FIG. 1;

FIG. 6 is an explanatory diagram for explaining an overpressure preventing action when an abnormal pressure rise of the bag-shaped weir body of the automatic rubber dam falling device provided with the overpressure preventing mechanism in FIG. 1;

FIG. 7 is an explanatory view showing the state of each part when the bag-like weir body of the automatic weirer of the rubber weir provided with the overpressure prevention mechanism in FIG.

FIG. 8 is an explanatory view showing the state of each part of the bag-shaped weir body of the rubber weir having the overpressure prevention mechanism shown in FIG.

FIG. 9 is an explanatory view showing a state of each part at the time of an operation of manually erecting the bag-shaped weir from the manually laid-down state shown in FIG. 7;

FIG. 10 is an overall configuration diagram of another embodiment of an automatic falling device for a rubber weir provided with an overpressure prevention mechanism according to the present invention.

FIG. 11 is a configuration diagram showing an example of a float valve automatic opening structure used in the present invention.

FIG. 12 is a configuration diagram showing another example of the float valve automatic opening structure used in the present invention.

FIG. 13 is a configuration diagram showing another example of the float valve automatic opening structure used in the present invention.

FIG. 14 is a configuration diagram showing an example of a conventional float valve automatic opening structure.

FIG. 15 is an overall configuration diagram of an automatic falling device of a rubber weir provided with a multi-gate overpressure prevention mechanism used in the present invention.

FIG. 16 is an overall configuration diagram of a conventional automatic fall device for a rubber weir provided with an overpressure prevention mechanism.

FIG. 17 is an overall configuration diagram of a conventional rubber dam automatic falling device equipped with a conventional overpressure prevention mechanism.

[Explanation of symbols]

 1 Automatic Falling Device for Rubber Weir with Overpressure Prevention Mechanism 1a Automatic Falling Device for Rubber Weir with Overpressure Prevention Mechanism 1b Automatic Falling Device for Rubber Weir with Overpressure Prevention Mechanism 2 Bag-shaped Weir Body 2a Bag-like Weir body 2b Bag-like weir body 2c Bag-like weir body 3 Blower 3a Blower 4 Water tank 4a Water tank 5 Upper water tank 5a Upper water tank 6 Lower water tank 6a Lower water tank 7 Float 7a Float 8 Bottom plate 9 Supply / exhaust pipe 9a Supply / exhaust pipe 9b Exhaust pipe 9c Supply / exhaust pipe 10 Intake valve 10a Inlet valve 11 Branch pipe 12 Exhaust valve 12a Exhaust valve 13 Communication pipe 14 Air pipe 15 Pumping valve 16 Branch pipe 17 Float valve 17a Float valve 18 Water surface 19 U-shaped communication pipe 19a U-shaped communication pipe 19b U-shaped communication pipe 19c U-shaped communication pipe 20 Bent part 21 Weir bottom 22 Latch 23 Weight 24 Bucket 25 Conductor Tube 26 siphon 27 U-shaped pipe 28 bent part 29 the liquid medium 30 Mizufukan 31 hanging tube 32 bottom plate H1 head pressure H2 head pressure H3 head pressure

Claims (4)

(57) [Claims] 1. A rubber weir having a mechanism for allowing air to flow into and out of a bag-like weir of a flexible membrane to expand and contract the bag-like weir to raise and lower the bag-like weir and to prevent overpressure of the bag-like weir. The automatic fall device of the rubber weir, the automatic fall device of the rubber weir, a blower, a supply and exhaust pipe connecting the blower and the bag-shaped weir body and providing an intake valve and an exhaust valve in the middle, at least the river A water tank comprising an upper water tank disposed above the water surface and opening the upper side and a lower water tank disposed below the water tank, and a communication pipe erected between the bottom plate side of the upper water tank and the bottom plate side of the lower water tank A U-shaped communication pipe which communicates the communication pipe with the supply / exhaust pipe and has a bent portion below the bottom plate of the lower water tank;
An air pipe installed between the blower and the lower water tank, and a float valve provided on a branch pipe of the air pipe and opened and closed by a float floating on the water surface of the river, wherein the blower and each valve A rubber weir provided with an overpressure prevention mechanism, which is capable of opening / closing the bag to raise and lower the bag-like dam, and capable of automatically preventing and falling down the bag-like dam. Automatic lodging device. 2. The water tank according to claim 1, wherein an upper water tank and a lower water tank are defined by each other and connected by the communication pipe, and the U-shaped communication pipe is connected to the communication pipe. Automatic falling device for rubber dam with overpressure prevention mechanism. 3. A drooping pipe communicating with the upper water tank is connected to a bottom plate of the upper water tank of the water tank, and a lower end of the drooping pipe is opened on the bottom plate side of the lower water tank, and the U-shaped communication pipe is connected to the lower water tank. 2. An automatic falling device for a rubber weir provided with an overpressure prevention mechanism according to claim 1, wherein one end of the rubber weir is opened by entering into the drooping tube. 4. The rubber provided with an overpressure prevention mechanism according to claim 1, wherein a plurality of sets of the bag-shaped weir and the supply / exhaust pipe and a U-shaped communication pipe engaged with the weir are provided. Automatic wedging device for weirs.