JP2001165833A - Liquid level automatic changing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level automatic changing device which can simplify the configuration, facilitate the manufacture and assembly, and reduce the cost. SOLUTION: A water level changing cylindrical body 12 is erected on an upper portion of a water storage tank 11 to be tested, a lifting pipe 16a constituting a water discharge pipe 16 is stored in the water level changing cylindrical body 12, a lead pipe 16b is connected to the lifting pipe 16a, and a downcomer 16c is connected to the lead pipe 16b. A throttle 17 is provided on a lower end of the downcomer 16c. When water is supplied in the water storage tank 11 and the water level changing cylindrical body 12 and the water level rises from the low level LL to the high level HL, water is introduced into the water discharge pipe 16. The pressure in the water discharge pipe 16 becomes negative by the throttle 17, and the water discharge pipe 16 demonstrates the siphon function to start the water discharge. Since the water discharge is more than the water supply, the water level drops from the high level HL to the low level LL, and the water discharging is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic liquid level changing device, and more particularly, to automatically and repeatedly changing a liquid level in a liquid storage tank, for example, to measure the durability of a water storage tank, The present invention relates to an automatic liquid level fluctuation device suitable for intermittently supplying a liquid.

[0002]

2. Description of the Related Art Generally, a water storage tank receives a fluctuation in water pressure depending on the amount of water, and it is necessary to perform an endurance test for measuring whether the fluctuation of the water pressure due to the repetitive fluctuation of the water level causes damage to the tank body. The durability test of this water tank is performed as follows. A predetermined amount of water is supplied from the water supply pipe into the water tank, and the water level sensor detects that the water level in the water tank has reached a high level. Next, in response to a drain operation signal from the control device, the on-off valve provided on the drain pipe is opened to start draining.

After that, when the water level becomes low level, a water level sensor is operated, an electromagnetic on-off valve is closed by an operation signal from the control device, and a predetermined amount of water is supplied to the water storage tank.
When the level becomes high again, the draining operation described above starts,
Thereafter, water supply and drainage are repeatedly performed in the same manner.

[0004]

However, the above-mentioned conventional water tank durability test apparatus controls a plurality of water level sensors for detecting a high level and a low level water level, an electromagnetic on-off valve provided on a drainage channel, and an on-off valve. Therefore, there is a problem that the number of parts is large, the structure is complicated, and the cost cannot be reduced.

In addition, since the water level sensor, the electromagnetic on-off valve, and the control device are frequently operated repeatedly, there has been a problem that the contacts and sliding portions are easily worn and have low durability. On the other hand, in agricultural irrigation, when a predetermined amount of water is regularly supplied to crops and soil, an electromagnetic on-off valve provided in the middle of a water supply pipe is opened for a predetermined time by an operation signal from a control device. Water was supplied from a water source.

For this reason, there were problems in cost and durability as in the durability test of the water tank. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the conventional technology and to automatically change the liquid level in a water storage tank with a simple configuration, thereby reducing the cost. It is to provide a device.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises a liquid supply means for continuously supplying a liquid, and a liquid dropped from the liquid supply means. A liquid storage tank to be stored, a liquid pumping pipe vertically arranged in the liquid storage tank, and an outlet pipe that is led out through a side wall of the liquid storage tank to an upper end of the liquid pumping pipe. When,
The drainage pipe connected downward to the outer end of the outlet pipe, and the drainage amount of the drainage pipe consisting of the pumping pipe, the outlet pipe, and the drainage pipe is larger than the liquid supply amount of the liquid supply means. The passage area of the drainage pipe is set so that the liquid level in the liquid storage tank rises and the liquid flowing from the pumping pipe to the outlet pipe and the drainage pipe flows into the drainage pipe. And a negative pressure applying means for reducing the pressure in the outlet pipe to a negative pressure and exerting the function of the siphon.

According to a second aspect of the present invention, in the first aspect, the negative pressure applying means is a throttle provided at a lower end opening of the downcomer pipe, which scatters the downflow and lowers the lower section of the downcomer pipe. A gist of the invention is that a liquid film is formed in the opening, and the structure is such that air entering the downcomer pipe from the outside through the lower end opening is suppressed.

A third aspect of the present invention is characterized in that, in the second aspect, the throttle is a ring-shaped fixed throttle fitted to a lower end portion of the downcomer pipe. According to a fourth aspect of the present invention, in the second aspect, the throttle is supported separately from the downcomer pipe and detachably with respect to the lower end opening, and is always held at the contact position by a biasing means. The gist is that

According to a fifth aspect of the present invention, in the first aspect, the negative pressure applying means is a liquid storage tank arranged so as to cover a lower end portion of the downcomer pipe, and has an opening in the liquid storage state. The gist is that it is configured to cover.

According to a sixth aspect of the present invention, in the first aspect, the negative pressure applying means is a variable throttle provided in a downcomer pipe, and is controlled to be opened and closed by an electric actuator. That is the gist.

According to a seventh aspect of the present invention, in the first aspect, a liquid level fluctuation space between an inner peripheral surface of the liquid level fluctuation cylinder and an outer peripheral surface of the liquid rise pipe is provided above the liquid riser pipe. And a communication hole communicating with the pumping passage in the pumping pipe is provided, and the communication hole is closed from the start of the drainage operation by the drainage pipe to immediately before the end thereof, and the flow rate of the drainage is set. The gist of the invention is that an opening / closing control valve for opening the communication hole and promoting the drainage operation is provided when the flow rate is reduced by detecting the flow rate.

According to an eighth aspect of the present invention, in the seventh aspect, the opening / closing control valve is supported by being penetrated by an opening provided in the liquid pumping pipe, and internally communicates the liquid level fluctuation space and the liquid pumping passage. A cylindrical holder having a communication hole, a supporting member supported reciprocally through bearings (24, 25) inside the holder, and a liquid level provided at one end of the supporting member, An on-off valve that opens and closes the communication hole on the fluctuation space side, and a pressure-sensitive plate that is attached to the other end of the support member and senses the flow rate of pumped liquid in the pumping pipe and adjusts the opening of the on-off valve. The gist is that it is configured.

According to a ninth aspect of the present invention, in the ninth aspect, the holder is provided so as to be inclined so that the on-off valve is at the bottom and the pressure sensitive plate is at the top, and the flow rate of the pumped liquid acting on the pressure sensitive plate is reduced. The gist of the invention is that the on-off valve is moved to a position for opening the communication hole by its own weight when the value becomes equal to or less than the predetermined value.

According to a tenth aspect of the present invention, in the ninth aspect, the on-off valve is provided with a weight for changing and adjusting the weight thereof. According to an eleventh aspect of the present invention, in the seventh aspect, the open / close control valve is configured to open / close an opening provided in the liquid pumping tube and to be elastically held at a position where the opening is always opened. The gist comprises a valve and a pressure-sensitive plate which is connected to the on-off valve and adjusts the opening of the on-off valve by sensing the flow rate of the liquid in the pumping pipe.

The gist of the invention described in claim 12 is that, in claim 1, a communication hole is formed at a predetermined height from the lower end opening edge of the pumping pipe. Claim 13
The liquid storage tank according to claim 1, wherein the liquid storage tank is connected to a tank main body located at a lower part and an opening provided on an upper wall surface of the tank main body and accommodates the liquid pumping pipe. The gist of the present invention is that it is constituted by a cylindrical body.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention as a water tank durability test apparatus will be described below with reference to FIGS.

As shown in FIGS. 1 and 2, an opening 11a is provided on the upper surface of a test water tank 11 having a rectangular box shape, and a water level changing cylinder 12 is provided upright on the opening 11a. . The distal end of the water supply pipe 13 is disposed at the upper end opening of the water level fluctuation cylinder 12 so that water is supplied from the water source 14 into the test water storage tank 11 and the water level fluctuation cylinder 12 via the manual opening / closing valve 15 in a fixed amount. It has become.

In this embodiment, a water storage tank T is constituted by the test water storage tank 11 and the water level changing cylinder 12. A pumping pipe 16a that constitutes a part of the drainage pipe 16 is disposed in the vertical direction in the water level fluctuation cylinder 12, and a part of the drainage pipe 16 is also formed at the upper end of the pumping pipe 16a. Outlet pipe 16
b is connected to one end. The outer end of the outlet pipe 16b is connected to the upper end of a downcomer 16c that also forms part of the drain pipe 16. An inlet 16d at the lower end of the pumping pipe 16a is disposed at an upper position in the test water tank 11, and an outlet 16e at a lower end of the downcomer 16c is disposed further below the inlet 16d.

A throttle 17 as a negative pressure applying means is fitted and fixed to the lower end of the downcomer 16c.
The diameter of a is set smaller than the inner diameter of the downcomer 16c. Then, the drainage moving down the downcomer 16c collides with the annular turning surface 17b of the throttle 17 toward the center, forms a water curtain (liquid film) at the outlet 16e, and prevents external air from flowing. Intrusion is suppressed, and the internal pressure of the outlet pipe 16b is set to a negative pressure.

In this embodiment, the passage area of the drain pipe (16), that is, the diameter of the throttle hole 17a, is set so that the drainage amount of the drain pipe 16 is larger than the liquid supply amount of the water supply pipe 13. When the water supplied from the water supply pipe 13 is naturally dropped without artificially applying pressure, the passage area of the throttle 17 is set to be larger than the passage area of the water supply pipe 13. When this area ratio is large, the cycle time of drainage becomes short.

On the wall near the upper end of the pumping pipe 16a,
As shown in FIG. 4A, an opening 16f is provided.
An opening / closing control valve 21 is mounted on the opening 16f.
Cylindrical holder 22 constituting the opening / closing control valve 21
Are fixed obliquely through the opening 16f. Inside the holder 22, a water level fluctuation space R1 between the inner peripheral surface of the water level fluctuation cylinder 12 and the outer peripheral surface of the water pumping pipe 16a,
A communication hole 22a communicating with the pumping passage R2 of 6a is formed. A support member 23 is supported inside the communication hole 22 a via bearings 24 and 25 attached to both ends of the holder 22 so as to be able to reciprocate vertically and obliquely.

As shown in FIG. 5, the support member 23 is
4 and a forked portion 23b supported by the bearing 25. An on-off valve 26 is attached to the tip of the rod portion 23a of the support member 23, that is, on the side of the water level fluctuation space R1.
6, the water level fluctuation space R of the communication hole 22a of the holder 22
The end opening edge 22b on one side can be opened and closed. At the tip of the forked portion 23b of the support member 23, a water pump 16
The pressure-sensitive plates 27 are attached at two locations so as to be located at the pumping passage R2 in a. The pressure-sensitive plate 27 is connected to the pumping pipe 16a.
When the flow velocity of the drainage flowing upward through the pumping passage R2 exceeds a set value, the drainage is moved obliquely upward, and the on-off valve 26 is closed.

The holder 22 is provided so as to be inclined such that the on-off valve 26 is at the lower position and the pressure-sensitive plate 27 is at the upper position. When the pressure of the drainage acting on the pressure-sensitive plate 27 becomes lower than a predetermined value, the holder 22 is opened. Is moved to a position to open the communication hole 22a by its own weight.

Next, the operation of the durability test apparatus for a water tank configured as described above will be described. Now, water source 14
When the manual opening / closing valve 15 is opened from the water supply pipe 13 and water is supplied at a constant flow rate from the water supply pipe 13 into the water level variation cylinder 12 and the test water tank 11, the water level in the test water tank 11 gradually rises, It reaches the lowermost entrance 16d of 16a. Thereafter, the water level rises in the water level fluctuation cylinder 12 and rises to the high level H shown in FIG.
It rises to L. In this state, since the on-off valve 26 of the on-off control valve 21 is open, water enters the pumping pipe 16a and the outlet pipe 16b, and starts flowing from the outlet pipe 16b to the downcomer 16c.

When this drainage is started, the amount of water is initially small, so that the water flows down the inner wall surface of the downcomer 16c. Then, the drainage is rebounded in the horizontal direction by a throttle 17 provided on the inner peripheral surface of the outlet 16e of the downcomer 16c, and the water curtain is formed horizontally so as to cover the outlet 16e. (See FIG. 3) As a result, the outlet pipe 16b and the downcomer 1
The air initially present in the inside of the downcomer 6c is easily discharged to the outside from the outlet 16e, the intrusion of air from the outside into the downcomer 16c is suppressed, and the drainage is quickly filled in the downcomer 16c, and the outlet pipe is provided. The internal pressure at 16b becomes a negative pressure. Accordingly, the siphon function is exhibited, and the downcomer 16
The water is discharged to the outside from the outlet 16e (throttle hole 17a) of c. Therefore, the water in the test reservoir 11 is sucked from the inlet 16d of the water pump 16a, moves upward, passes through the outlet pipe 16b, reaches the downcomer 16c, and is sequentially discharged to the outside.

The flow velocity of the drainage flowing in the pumping pipe 16a reaches the maximum flow rate immediately after the start of drainage, and the pressure-sensitive plate 27 is urged through the support member 23 in the direction of closing the on-off valve 26.
The communication hole 22a is kept closed. Therefore, water sucked from the inlet 16d of the drain pipe 16 is drained.

The amount of water supplied by the water supply pipe 13 is set to be constant per unit time, and the amount of water drained by the drain pipe 16 is set to be larger than this supply amount. Therefore, as the discharging operation of the water in the test water tank 11 continues, the water level in the water level change cylinder 12 drops from the high level HL, and is eventually displaced to the position indicated by the low level LL in the test water tank 11.

As a result, no water can be sucked up from the pumping pipe 16a, and the drainage through the drain pipe 16 is stopped. For this reason, all the water in the water level variation cylinder 12 and the drain pipe 16 is discharged and air enters.

In the final stage of the drainage operation, the flow velocity of the drainage flowing in the water pumping pipe 16a decreases, so that the pressure sensitive plate 27 is moved via the support member 23 in the direction to open the on-off valve 26. As a result, drainage operation is stopped early,
The water remaining in the pumping pipe 16a is immediately discharged to the test reservoir 1
1 and the inside of the drain pipe 16 is quickly filled with air. Therefore, the drainage operation is reliably and promptly completed.

When the water supplied from the water supply pipe 13 gradually rises from the low level LL to the high level HL, the draining operation is performed again as described above. next,
The effects grasped from the above embodiment are listed together with the configuration.

(1) In the above-described embodiment, a throttle 17 is provided as a negative pressure applying means at the lower end outlet 16e of the downcomer 16c of the drain pipe 16, and water is supplied by the edge turning surface 17b forming the throttle hole 17a. By turning to the center side, a water film is formed to suppress the intrusion of air from outside into the downcomer 16c. Therefore, when the water level in the test water storage tank 11 changes from the low level LL to the high level HL, the inside of the drain pipe 16 becomes negative pressure, the drain pipe 16 functions as a siphon pipe, and the drain operation is started. Further, since the amount of water discharged from the drain pipe 16 is higher than the amount of water supplied from the water supply pipe 13, the water level is changed from the high level HL to the low level LL, and the drain operation can be intermittently repeated.

Further, the durability test based on the water level fluctuation of the test reservoir 11 can be stably performed over a long period of time without using a complicated and expensive durability test device such as an electromagnetic on-off valve, a water level sensor or a control device.

(2) In the above embodiment, since the open / close control valve 21 is mounted on the upper end of the water pumping pipe 16a, the drainage operation can be quickly and reliably completed. That is, immediately before the end of the draining operation, the communication hole 22a is opened to allow air to flow into the pumping pipe 16a, and the draining operation by the drain pipe 16 can be stopped immediately.

(3) In the above embodiment, the open / close control valve 21
The opening / closing valve 26 is configured to open the communication hole 22a by its own weight, so that the structure can be simplified by eliminating a spring or the like.

The above embodiment can be modified and embodied as follows. In another example shown in FIG. 6, a bracket 29 is attached to the outer peripheral surface of the lower end of the downcomer 16 c, and the diaphragm 17 is rotatably connected to the bracket 29 via a connecting pin 30. Hold in operating position. When the draining operation is performed, the throttle 17 is rotated to the inoperative position by the water pressure.

In another example shown in FIG. 7, the liquid storage tank 32 is arranged so as to cover the lower end of the downcomer 16c. In this alternative example, when the drainage operation is started, the water stored in the liquid storage tank 32 is pushed out, and the air in the downcomer 16c is discharged to the outside together with the water. Therefore, it is possible to efficiently prevent the backflow of the air. It is possible to quickly shift to drain operation.

In another example shown in FIG. 8, a variable throttle 33 is attached to the lower end of the downcomer 16c, and its actuator 3
4 is operated by a signal from the control device 35 to change the aperture amount.

In this alternative example, the actuator 34 and the control device 35 are required, but the control device 35 is configured so that the variable throttle 33 is temporarily stopped only when the drain operation is started, and is opened during the drain operation. Since it suffices, the configuration of the control device can be simplified. Further, the amount of narrowing of the variable throttle 33 can be adjusted, and the start time of the draining operation can be easily set.

In another example shown in FIG. 9, an elastically deformable on-off valve 26 is mounted on the outer surface of the pumping pipe 16a so that the opening 16f can be opened and closed, and the support member 23 and the pressure-sensitive plate 27 are connected to one surface thereof. I have. In this alternative example, the configuration of the on-off control valve 21 can be simplified.

As shown in FIG. 10, the opening and closing control valve 21 may be of an opening and closing lever type. In this alternative example, a tilting lever 41 that supports the pressure-sensitive plate 27 is supported on a bracket 42 so as to be tiltable by a shaft 43, and one end of the support member 23 is connected to the tilting lever 41 by a pin 44, and the on-off valve 2 is opened.
6 is opened and closed. When the pressure-sensitive plate 27 receives the upward water pressure, the on-off valve 26 is closed as shown by a solid line in FIG. 10, and when the water pressure falls below a predetermined value, the on-off valve 26 is opened as shown by a chain line.

In the configuration in which the opening / closing control valve 21 is omitted, as shown in FIG. 11, communication holes 16g are provided at a plurality of locations near the lower end of the water pumping pipe 16a and at equal intervals at the same height. Is formed. These communication holes 1
6g has a function of facilitating the introduction of air into the pumping pipe 16a at the end of the draining operation, thereby quickly terminating the draining operation. If there is no communication hole 16g, a gap is formed almost simultaneously between the entire periphery of the lower end of the inlet 16d and the water surface at the low level LL, and the air enters to shut off the drainage, but this operation is smooth. Is unlikely to occur.

As shown in FIG. 12, aperture 17a may be provided in aperture 17 at several or many locations. In this alternative example, since a water curtain is likely to occur, the start time of the discharging operation can be advanced.

As shown in FIG. 13, a joint 46 may be interposed in the middle of the downcomer 16c, and a throttle 17 may be provided on the joint 46. In this case, the ratio of the height dimension of the throttle 17 from the lower end of the downcomer 16c to the total height of the downcomer 16c may be, for example, 10 to 70%. Further, a plurality of apertures 17 can be provided in the intermediate portion.

Although not shown, the on-off valve 2 of the control valve 21
A plurality of weights may be provided in a detachable manner so that the weight of 6 can be adjusted. In this alternative,
The end time of drainage can be changed by the weight for changing and adjusting the weight of the on-off valve 26.

Although not shown, the water discharged from the downcomer 16 c is temporarily stored in a water storage tank, and this water is returned to the water source 14 side of the water supply pipe 13 by a water supply pump, or the water is supplied to the water level variation cylinder 12. Water may be supplied directly.

Although not shown, the installation position of the open / close control valve 21 may be changed to the outer peripheral wall of the outlet pipe 16b. In the above embodiment, the water tank is embodied,
Other than water, for example, it may be embodied as a device for automatically changing the level of a chemical liquid.

Although not shown, the present invention can be embodied as a field irrigation device or hydroponic cultivation other than a water tank durability test device, or as a washing device that periodically cleans a toilet bowl. .

In the above-described embodiment, as shown in FIG. 1, the height position of the lower end outlet 16e of the downcomer 16c is lower than the height position of the inlet 16d. It may be above.

The height of the outlet 16e of the downcomer 16c can be changed so that the water level of the low level LL can be adjusted. In this embodiment, for example, the downcomer pipe 16c is divided into a plurality of pipes,
May be provided so that each of the divided pipes can be connected in series.

[0051]

As described in detail above, according to the first to sixth aspects of the present invention, the liquid level can be automatically changed with a simple configuration, and the cost can be reduced.

According to the second or third aspect of the present invention, the structure of the negative pressure applying means can be simplified, and the manufacturing can be easily performed. According to the invention described in claim 4 or 6, the drainage operation after the siphon function is provided to the drainage pipe by the throttle can be quickly performed.

According to the fifth aspect of the present invention, the structure of the negative pressure applying means can be simplified, and the function of the siphon can be quickly provided to the drain pipe. Claim 7
In the described invention, since the opening / closing control valve is provided at the upper part of the pumping pipe or at the outlet pipe, the end time of the draining operation can be advanced,
The liquid level fluctuation cycle time can be shortened.

According to the eighth aspect of the present invention, the structure of the on-off control valve is simplified, and the manufacturing and assembling work can be easily performed. According to the ninth aspect of the invention, the configuration of the on-off control valve can be further simplified.

According to the tenth aspect, the end time of drainage can be changed by a weight for changing and adjusting the weight of the on-off valve. According to the eleventh aspect of the invention, the configuration of the on-off control valve is simplified, and the manufacturing and assembling operations can be easily performed.

According to the twelfth aspect of the present invention, the drainage operation can be completed quickly. According to the invention of claim 13, since the liquid storage tank is constituted by the main body and the liquid level fluctuation cylinder, the width of change of the liquid pressure due to the fluctuation of the liquid level can be set to be large with a small volume, and particularly, the water storage tank Suitable for durability test.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment in which the present invention is embodied in a water tank test apparatus.

FIG. 2 is a longitudinal sectional view showing a state in which a liquid level is lowered.

FIG. 3 is an enlarged sectional view of a lower end portion of a liquid downcomer.

FIG. 4 is an enlarged sectional view showing an open / close control valve in an open state and a closed state.

FIG. 5 is an enlarged plan sectional view showing an on-off control valve.

FIG. 6 is a sectional view showing another example of the negative pressure applying means.

FIG. 7 is a sectional view showing another example of the negative pressure applying means.

FIG. 8 is a sectional view showing another example of the negative pressure applying means.

FIG. 9 is a sectional view showing another example of the opening / closing control valve.

FIG. 10 is a sectional view showing another example of the opening / closing control valve.

FIG. 11 is a cross-sectional view showing another example of the configuration for promoting the end of the drainage operation.

FIG. 12 is a perspective view showing another example of the stop.

FIG. 13 is a cross-sectional view showing another example of the mounting position of the stop.

[Explanation of symbols]

T: water storage tank as a liquid storage tank, R1: water (liquid) level fluctuation space, R2: pumping (liquid) passage, 11: tank body, 11a ...
Opening, 12: water (liquid) level variable cylinder, 16: drainage pipe as drain pipe, 16a: pumping pipe as pumping pipe, 16b ...
Outlet pipe, 16c ... downcomer as a downcomer pipe, 16f ... opening, 17 ... throttle, 17a ... throttle hole, 17b ... turning surface, 2
DESCRIPTION OF SYMBOLS 1 ... Opening / closing control valve, 22 ... Holder, 22a ... Communication hole, 2
3 Support member, 26 On-off valve, 27 Pressure-sensitive plate.

Claims (13)

[Claims] 1. A liquid supply means (13, 14) for continuously supplying a liquid, a liquid storage tank (T) for storing a liquid dropped from the liquid supply means, and a liquid storage tank (T). A liquid storage tank (T) with respect to the upper end of the liquid pumping pipe (16a) disposed vertically in the liquid storage tank (T);
Outer pipe (16b) penetrating through the side wall of the pipe and led out
And a drainage pipe (16c) downwardly connected to the outer end of the outlet pipe (16b); and a drainage liquid comprising the pumping pipe (16a), the outlet pipe (16b) and the drainage pipe (16c). The passage area of the drainage pipe (16) is set so that the drainage amount of the pipe (16) is larger than the liquid supply amount of the liquid supply means (13, 14); T) rises and the pumping pipe (16)
The liquid flowing from a) into the outlet pipe (16b) and the descending pipe (16c) is filled in the descending pipe (16), and the pressure in the outlet pipe (16b) is reduced to a negative pressure. An automatic liquid level fluctuation device comprising: a negative pressure applying means (17) for exerting a function. 2. The descending pipe according to claim 1, wherein the negative pressure applying means is a throttle (17) provided at a lower end opening (16e) of the descending pipe (16c), and scatters the descending liquid. (1
6c) An automatic liquid level changing device configured to form a liquid film in the lower opening and to suppress air from entering the liquid down pipe (16c) from the outside through the lower opening. 3. The diaphragm (17) according to claim 2, wherein:
Is a liquid level automatic fluctuation device which is a ring-shaped fixed throttle fitted to the lower end of the liquid down pipe (16c). 4. The diaphragm (17) according to claim 2, wherein:
Is separate from the downcomer pipe (16c) and the lower end opening (16c).
e) is supported so as to be able to come and go with respect to e.
The liquid level automatic fluctuation device held at the contact position according to 1). 5. The liquid storage tank according to claim 1, wherein the negative pressure applying means is a liquid storage tank (32) arranged to cover a lower end portion of the liquid downcomer pipe (16c), and the liquid storage tank has an opening (16e) in a liquid storage state. ) Is configured to cover the liquid level automatic fluctuation device. 6. The negative pressure applying means according to claim 1, wherein the negative pressure applying means is a variable throttle (33) provided in the liquid downcomer (16c), and is controlled to be opened and closed by an electric actuator (34). Automatic liquid level fluctuation device. 7. The pump according to claim 1, wherein an inner peripheral surface of the liquid level changing cylinder (12) and the liquid pumping pipe (1) are provided above the liquid pumping pipe (16a).
A communication hole (22a) is provided for communicating the liquid level fluctuation space (R1) between the outer peripheral surface of the liquid storage tube 6a) and the pumping passage (R2) in the pumping pipe (16a). ), The communication hole (22a) is closed from the start to the end of the drainage operation by the drainage pipe (16), and the communication hole (22a) is closed when the flow rate of the drainage is sensed and the flow rate decreases. A liquid level automatic fluctuation device provided with an opening / closing control valve (21) for opening a valve and promoting a drainage operation. 8. The open / close control valve (2) according to claim 7,
1) a communication hole (22a) penetratingly supported by an opening (16f) provided in the liquid pumping pipe (16a) and communicating the liquid level fluctuation space (R1) with the liquid pumping passage (R2). A cylindrical holder (22) having a support member (23) supported reciprocally via bearings (24, 25) inside the holder (22); and one end of the support member (23) And an on-off valve (26) for opening and closing the communication hole (22a) on the side of the liquid level variation space (R1), and attached to the other end of the support member (23); A) a pressure-sensitive plate (27) for adjusting the opening of the on-off valve (26) by sensing the flow rate of the pumped liquid in (). 9. The holder according to claim 8, wherein
2) The on-off valve (26) is provided at an inclination so that the pressure-sensitive plate (27) is at the bottom and the pressure-sensitive plate (27) is at the top. (26) An automatic liquid level changing device wherein the self-weight is moved to a position where the communication hole (22a) is opened by its own weight. 10. The on-off valve (2) according to claim 9,
6) An automatic liquid level fluctuation device provided with a weight for changing and adjusting the weight. 11. The opening / closing control valve (21) according to claim 7, wherein the opening / closing control valve (21) is provided in an opening (16f) provided in the pumping pipe (16a).
And an opening / closing valve (26) elastically held at a position where the opening (16f) is always opened, and connected to the opening / closing valve and lifted in the pumping pipe (16a). A liquid level automatic fluctuation device comprising a pressure sensitive plate (27) for adjusting the opening of the on-off valve (26) by sensing the flow rate of the liquid. 12. The pump according to claim 1, wherein the liquid is pumped.
The communication hole (16) is located at a predetermined height from the lower edge of the opening.
An automatic liquid level fluctuation device in which g) is formed. 13. The liquid storage tank (T) according to claim 1, wherein the liquid storage tank (T) is connected to a lower tank body (11) and an opening (11a) provided on an upper wall surface of the lower tank body (11). And an automatic liquid level changing device including a liquid level changing cylinder (12) accommodating the liquid pumping pipe (16a).