WO2019239750A1

WO2019239750A1 - Vertical shaft pump

Info

Publication number: WO2019239750A1
Application number: PCT/JP2019/018488
Authority: WO
Inventors: 祐治兼森
Original assignee: 株式会社酉島製作所
Priority date: 2018-06-13
Filing date: 2019-05-09
Publication date: 2019-12-19
Also published as: JP2019214976A; JP6985985B2

Abstract

This vertical shaft pump 10 is provided with: a pump casing 12 which is disposed in a water suction tank 1 so as to extend in the vertical direction; a vane wheel 25 which is disposed in an upper part of a duct tube 16 inside the pump casing 12; and a first air supply pipe 30 which is disposed outside the pump casing 12. An air intake opening 30a of the first air supply pipe 30 is positioned higher than a highest water level that is higher than a water discharge initiation position LWL, while an air supply opening 30b of the first air supply pipe 30 is connected to the duct tube 16. The duct tube 16 is provided with an outer tube 17 and an inner tube 18 having a flared portion 18b, while the air supply opening 30b of the first air supply pipe 30 is connected to this flared portion 18b of the inner tube 18.

Description

Vertical shaft pump

The present invention relates to a vertical shaft pump.

There is known a stand-by type vertical shaft pump which is started in advance before water flows into the water absorption tank. The vertical shaft pump disclosed in Patent Document 1 includes an air supply pipe piped outside the pump casing. A double trumpet pipe having an outer cylinder and an inner cylinder is disposed at the lower end of the pump casing, and the lower end (air supply port) of the air supply pipe is connected to the inner cylinder. The upper end (intake port) of the air supply pipe is arranged above the installation floor that closes the upper part of the water absorption tank, that is, above the maximum water level determined for the water absorption tank.

Japanese Patent No. 4690134

In the pump of Patent Document 1, nothing is taken into consideration to ensure the distance between the lower end of the trumpet pipe and the bottom of the water absorption tank. Specifically, in Patent Document 1, the position where the maximum load due to the dynamic pressure in the pump casing is lowered with the drainage start water level as a reference is the connection position of the supply pipe. Therefore, when the flow rate of the pump is large, the air supply pipe cannot be connected unless the overall length of the trumpet pipe is increased. However, in the case of a water absorption tank with a shallow bottom, a pump using a trumpet pipe having a long overall length cannot be installed.

An object of the present invention is to provide a vertical shaft pump that can secure the space between the bottom of the water absorption tank and the lower end of the pump casing and can be installed even in a shallow water absorption tank.

One aspect of the present invention is disposed in a water absorption tank so as to extend in the vertical direction, and has a pump casing having a trumpet pipe for sucking water in the water absorption tank at a lower end thereof, and is located at a predetermined drainage start water level of the water absorption tank. As described above, an impeller disposed above the trumpet pipe in the pump casing, and an intake port at one end disposed outside the pump casing so as to be positioned above a highest water level higher than the drainage start position And a first air supply pipe having an air supply port at the other end connected to the trumpet pipe, and the trumpet pipe is disposed in the outer cylinder so as to be positioned directly below the outer cylinder and the impeller. And an inner cylinder having a flare portion gradually spreading from the upper end toward the lower end, and the air supply port of the first air supply pipe is connected to the flare portion of the inner cylinder, The pump cable is Wherein the inner cylinder and outer ring is always spatially communication, it provides a vertical shaft pump.

According to this vertical shaft pump, the first air supply pipe is connected to the flare portion of the inner cylinder of the pump casing, and the dynamic pressure in the flare portion is lower than the dynamic pressure of the upper end opening portion of the inner cylinder. The dynamic pressure in the flare portion is lower than the atmospheric pressure when the water level is higher than the drainage start water level, and becomes higher than the atmospheric pressure when the water level is lower than the drainage start water level. Therefore, the air outside the pump casing does not flow into the inner cylinder when the water level is higher than the drainage start water level, and flows into the inner cylinder when the water level becomes lower than the drainage start water level. As a result, when the water level is higher than the drainage start water level, only water can be drained, and when the water level becomes lower than the drainage start water level, it is possible to shift to the air-water mixing operation. In this manner, by connecting the first air supply pipe to the flare portion of the inner cylinder, optimal air supply is possible without increasing the overall length of the trumpet pipe. Therefore, the space | interval of the bottom of a water absorption tank and the lower end of a pump casing can be ensured, and even if it is a shallow water absorption tank, a pump can be installed reliably.

In the vertical shaft pump of the present invention, since the first air supply pipe is connected to the flare portion whose dynamic pressure is lower than that of the upper end opening portion, optimum air supply is possible even if the overall length of the trumpet pipe is short. Therefore, the space | interval of the bottom of a water absorption tank and the lower end of a pump casing can be ensured, and even if it is a shallow water absorption tank, a pump can be installed reliably.

Sectional drawing which shows the vertical shaft pump which concerns on 1st Embodiment of this invention. Sectional drawing which shows the air lock state of the pump of FIG. The partially expanded sectional view of FIG. FIG. 4 is a partially enlarged sectional view of FIG. 3. FIG. 4 is a plan view of FIG. 3. The graph which shows the distribution curve of the pressure and speed in the inner cylinder of a trumpet pipe. Sectional drawing which shows a part of vertical shaft pump of 2nd Embodiment. The top view of FIG. Sectional drawing which shows a part of vertical shaft pump of 3rd Embodiment. The top view of FIG. Sectional drawing which shows a part of vertical shaft pump of 4th Embodiment. The top view of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a vertical shaft pump 10 (hereinafter referred to as “pump”) according to a first embodiment of the present invention. This pump 10 is provided with

air supply pipes

30 and 33 outside the pump casing 12, and is switched to a drainage (total water) operation, an air-water mixing operation, and an air lock (drainage shutoff) operation depending on the water level of the water absorption tank 1. It is a standby form.

(Outline of vertical shaft pump)
As shown in FIG. 1, the pump 10 includes a pump casing 12, a rotating shaft 22, and an impeller 25. Referring to FIG. 5, in the water absorption tank 1 in which the pump 10 is disposed, three sides between the installation floor 2 and the bottom wall 3 are closed by the side walls 4, and water is drawn from the left side without the side walls 4 in FIG. 5. Inflow.

Referring to FIG. 1, the pump casing 12 is fixed to an installation floor 2 that covers the upper part of the water absorption tank 1 so as to extend in the vertical direction in the water absorption tank 1. The pump casing 12 includes a pumping pipe 13 disposed in the water absorption tank 1 and a discharge pipe 20 disposed on the installation floor 2. The pumping pipe 13 includes a straight pipe 14, a vane casing 15, and a bell mouth 16, which are connected in this order from the upper side to the lower side. The discharge pipe 20 includes a discharge elbow 21 whose central axis is bent by 90 degrees, and is connected to the upper end of the straight pipe 14. A water supply pipe (not shown) for draining downstream is connected to the outlet of the discharge elbow 21.

The rotary shaft 22 passes through the discharge elbow 21 and is arranged in the pump casing 12 along the axis of the pumping pipe 13. Referring to FIG. 3, the rotating shaft 22 is rotatably supported by an underwater bearing 23 disposed in a bearing casing 15 a in the straight pipe 14 and the vane casing 15. The upper end of the rotating shaft 22 protrudes outward from the discharge elbow 21, and the penetrating portion thereof is liquid-tightly sealed by a shaft seal device.

The impeller 25 is disposed below the bearing casing 15 a so as to be positioned above the bell mouth 16 and is attached to the lower end of the rotary shaft 22. The upper end 25a of the impeller 25 is disposed at the same height as the drainage start water level LWL determined by the specifications.

A driving means (not shown) is mechanically connected to the upper end of the rotating shaft 22 protruding from the pump casing 12. As the drive means, an electric motor or a diesel engine which is one of internal combustion engines is used. When the driving means is driven, the impeller 25 is rotated integrally with the rotary shaft 22, so that the water in the water absorption tank 1 is discharged downstream through the pump casing 12.

As shown in FIG. 2, the preceding standby type pump 10 enables an air lock operation in which a water column WC is held in a pump casing 12, prevents the overwater bearing 23 from being overheated by surrounding water, and allows water to enter the water absorption tank 1. The pump 10 can be continuously operated even in the absence. In order to realize this air lock operation, a first air supply pipe 30 and a second air supply pipe 33 that supply air in the water absorption tank 1 into the pump casing 12 are arranged around the pump casing 12. Yes.

The first air supply pipe 30 is provided for switching from the drain operation to the air / water mixing operation, and the second air supply pipe 33 is provided for switching from the air / water mixing operation to the air lock operation. The state of air supply into the pump casing 12 through the

air supply pipes

30 and 33 is switched by the dynamic pressure in the pump casing 12.

The preceding standby type pump 10 is started by an operator based on information of a local weather observation system, for example. Since the impeller 25 is in the air at the beginning when the water level in the water absorption tank 1 is lower than that of the impeller 25, the pump 10 is operated in the air without draining. When the water level rises above the lower end of the impeller 25, the water in the water absorption tank 1 is sucked up by the impeller 25 and air is sucked in through the first air supply pipe 30, so that the pump 10 is in a mixed state of water and air. Switch to air / water mixing operation. When the water level rises above the drainage start water level LWL (the upper end 25a of the impeller 25), the suction of air through the first air supply pipe 30 is shut off, so the pump 10 is switched to a drainage operation that discharges only water. Change.

When the water level in the water absorption tank 1 falls below the drainage start water level LWL due to drainage, air is sucked again through the first air supply pipe 30, and the pump 10 is switched to the air / water mixing operation. When the water level falls below the drain cut-off water level LLWL, air is also sucked from the second air supply pipe 33, so that the pump 10 switches to the air lock operation that holds the water column WC without draining. Thereafter, when the water level rises above the drainage cutoff water level LLWL, the pump 10 switches to the air / water mixing operation again. That is, the operation state of the pump 10 is switched in the order of air lock operation, air / water mixing operation, drainage operation, air / water mixing operation, and air lock operation until the operator stops. *

The aforementioned drainage start water level LWL, drainage cutoff water level LLWL, and maximum water level HWL are defined as required specifications. These are defined as heights from the bottom wall 3 and are set to increase in the order of the drainage cutoff water level LLWL, the drainage start water level LWL, and the highest water level HWL, as shown in FIG. At high water levels above the drainage start water level LWL, it is necessary to discharge only water without mixing air. At a low water level lower than the drainage start water level LWL, mixing of air is allowed. At an ultra-low water level below the drainage cut-off water level LLWL, it is necessary to shift to an air lock operation without draining.

In the conventional advance standby type pump, since the connection position of the air supply pipe is set based on the set drainage start water level LWL and the maximum load in the pump casing, a long bell mouth may be required, In this case, it could not be applied to a water absorption tank having a shallow bottom. Therefore, in the present embodiment, by optimizing the connection position between the first supply pipe 30 and the pump casing 12, the first supply pipe 30 enters the pump casing 12 without increasing the overall length of the bell mouth 16. It is possible to supply air at a predetermined timing. Further, by optimizing the shape and connection position of the second air supply pipe 33, the air supply for pumping off is made more efficient.

Specifically, the bell mouth 16 is constituted by a double trumpet tube including an outer cylinder 17 and an inner cylinder 18. And the 1st air supply piping 30 is connected to the flare part 18b with comparatively low dynamic pressure of the inner cylinder 18. As shown in FIG. In addition, the second air supply pipe 33 is connected to the cylinder portion 18 a having a relatively high dynamic pressure in the inner cylinder 18. As a result, it is possible to execute air supply optimal for operation switching. Details are as follows.

(Details of Bellmouth)
As shown in FIG. 4, the bell mouth 16 includes an outer cylinder 17 connected to the lower end of the vane casing 15, an inner cylinder 18 disposed in the outer cylinder 17, and two or more connecting plates 19 that connect these. Is provided.

The outer tube 17 includes a cylindrical tube portion 17a and a flare portion 17b continuous with the lower end of the tube portion 17a. A flange portion 17c that is fastened to the vane casing 15 by a bolt is provided at the upper end of the cylindrical portion 17a. The flare portion 17b has a conical cylinder shape that gradually expands from the upper end toward the lower end.

The inner cylinder 18 is disposed in the outer cylinder 17 so as to be located immediately below the impeller 25, and protrudes downward from the lower end of the outer cylinder 17. The inner cylinder 18 includes a cylindrical tube portion 18a positioned on the same axis as the rotation shaft 22, and a flare portion 18b continuous with the lower end of the tube portion 18a. Referring also to FIG. 1, the upper end of the cylinder part 18 a is located at the middle part in the vertical direction of the flare part 17 b of the outer cylinder 17, and is arranged at the same position as the pumping cutoff water level LLWL. The flare portion 18b has a conical cylinder shape that gradually spreads from the upper end toward the lower end. The maximum outer diameter of the flare part 18b is smaller than the minimum inner diameter of the outer cylinder 17 (cylinder part 17a).

In the present embodiment, four connecting plates 19 are provided, and are arranged radially with an interval of 90 degrees about the axis of the rotating shaft 22. The inner edge portion 19 a of the connecting plate 19 has a shape along the outer surface shape from the upper end to the lower end of the inner tube 18, and is joined to the outer surface of the inner tube 18. The outer edge portion 19 b of the connecting plate 19 has a shape along the inner surface shape from the vicinity of the upper end of the outer cylinder 17 to the vicinity of the lower end thereof, and is joined to the inner surface of the outer cylinder 17. A lower edge portion 19c extending from the lower end of the inner edge portion 19a to the lower end of the outer edge portion 19b protrudes downward from the outer cylinder 17 and is inclined outward from the lower side toward the upper side. An upper edge portion 19d extending from the upper end of the inner edge portion 19a to the upper end of the outer edge portion 19b is accommodated in the outer cylinder 17, and is inclined outward from the lower side toward the upper side.

Thus, according to the bell mouth 16 in which the inner cylinder 18 is protruded from the outer cylinder 17, it is possible to suppress the generation of underwater vortices in the bottom wall 3 located below the pump casing 12. The underwater vortex is a water flow in which air is continuously or intermittently contained in the water flowing from the bottom wall 3 of the water absorption tank 1 toward the bell mouth 16. Since the underwater vortex interferes with the inner cylinder 18 and the connecting plate 19 projecting radially, the underwater vortex can be eliminated, so that the water in the water absorption tank 1 can be effectively drained to a low water level.

FIG. 6 is a graph showing the pressure and speed in the inner cylinder 18. The horizontal axis shows the distance (m) from the lower end of the inner cylinder 18, and the vertical axis shows the magnitude of pressure and speed. Referring to FIG. 6, it can be seen that the internal pressure gradually increases and the internal flow rate gradually increases from the lower end of the inner cylinder 18 toward the upper end. That is, the dynamic pressure in the inner cylinder 18 is lowest at the lower end and becomes higher toward the upper end. Therefore, by adjusting the connection position of the first air supply pipe 30 with respect to the inner cylinder 18, the suction lift ΔHa due to the maximum negative pressure during operation can be adjusted regardless of the depth of the water absorption tank 1.

(Details of the first air supply piping)
As shown in FIG. 1, the first air supply pipe 30 is a pipe having an intake port 30 a at the upper end and an air supply port 30 b at the lower end, and always makes the inside and outside of the pump casing 12 communicate spatially. Yes. Most of the first air supply pipe 30 is disposed outside the pump casing 12 and extends in the vertical direction along the pump casing 12.

The intake port 30a is disposed in the water absorption tank 1 and is located above the highest water level HWL. A folded portion 30c that is folded in a U shape is provided on the upper portion of the first air supply pipe 30 so that the intake port 30a opens downward. The inner top portion of the folded portion 30 c is the highest position in the first air supply pipe 30. The height of the first air supply pipe 30 from the bottom wall 3 to the inner top portion of the folded portion 30c is set to a value obtained by adding the suction head ΔHa due to the maximum negative pressure generated in the inner cylinder 18 by pumping to the maximum water level HWL. Has been.

Referring also to FIG. 4, a connection portion 30 d that is bent toward the bell mouth 16 and is connected to the inner cylinder 18 through the outer cylinder 17 is formed at the lower portion of the first air supply pipe 30. . The portion of the outer cylinder 17 through which the connection portion 30d passes is sealed in a liquid-tight manner. An air supply port 30b which is the tip of the connection portion 30d is connected to the flare portion 18b of the inner cylinder 18.

Referring to FIG. 4, the diameter D1 of the flare portion 18b to which the connection portion 30d (air supply port 30b) is connected is 1.4 times or more the diameter D2 of the cylindrical portion 18a. That is, the connecting portion 30d is connected to a portion of the flare portion 18b that is 1.4 times or more the diameter D2 of the cylindrical portion 18a. In other words, the cross-sectional area of the connection portion of the first air supply pipe 30 is at least twice the cross-sectional area of the upper end opening of the inner cylinder 18. Referring also to FIG. 6, the dynamic pressure at this connecting portion is 40% of the dynamic pressure at the upper end of the inner cylinder 18.

More specifically, the connection position of the connection part 30d with respect to the flare part 18b is set based on the following equation. ΔHa is a suction head (suction loss) of the inner cylinder 18, ζa is a loss factor in the inner cylinder 18, Vd is a suction port speed in the inner cylinder 18, and Vs is a suction port speed between the outer cylinder 17 and the inner cylinder 18. , Dd is the inner diameter of the inner cylinder 18, and Dd is the minimum inner diameter of the outer cylinder 17.

As shown in the above equation, the suction head ΔHa at an arbitrary position of the inner cylinder 18 can be calculated from the suction port speed Vd of the inner cylinder 18 and the loss coefficient ζa. Therefore, the magnitude | size of suction lift (DELTA) Ha can be adjusted as needed by connecting the connection part 30d (supply port 30b) to the appropriate position of the inner cylinder 18. FIG. As a result, even in the shallow water absorption tank 1, air can be supplied into the pump casing 12 at a predetermined timing, and an air-water mixing operation can be executed. Specifically, when the water level is higher than the drainage start water level LWL, the dynamic pressure is lower than the atmospheric pressure, and when the water level is lower than the drainage start water level LWL, the air supply is at a position where the dynamic pressure is higher than the atmospheric pressure. The mouth 30b is connected. Thereby, the air outside the pump casing 12 does not flow into the inner cylinder 18 when the water level is higher than the drainage start water level LWL, and flows into the inner cylinder 18 when the water level becomes lower than the drainage start water level LWL. . As a result, when the water level is higher than the drainage start water level LWL, only water can be drained, and when the water level becomes lower than the drainage start water level LWL, the operation proceeds to the air-water mixing operation.

As described above, the intake port 30a is opened at a position higher than the maximum water level HWL, and the supply port 30b is connected to the predetermined diameter portion of the flare portion 18b. Air supply is possible. Therefore, since the space | interval of the bottom wall 3 of the water absorption tank 1 and the lower end of the pump casing 12 can be ensured, even if it is the shallow water absorption tank 1, the pump 10 can be installed reliably.

Since the intake port 30a of the first air supply pipe 30 is opened in the water absorption tank 1, drainage does not catch up due to an unintended abnormality, and even when the water in the water absorption tank 1 flows back through the first air supply pipe 30, The water can be returned to the water absorption tank 1. Therefore, it is possible to suppress leakage of water onto the installation floor 2 on which the control base is arranged.

(Details of second air supply piping)
As shown in FIG. 1, the second air supply pipe 33 is a pipe that is bent in a generally inverted U shape, and allows the inside and outside of the pump casing 12 to always communicate spatially. Most of the second air supply pipe 33 is disposed outside the pump casing 12 and extends in the vertical direction along the pump casing 12. One end of the second air supply pipe 33 constitutes the air inlet 33a, and the other end of the second air supply pipe 33 constitutes the air inlet 33b.

The intake port 33 a is formed at the lower end of the first pipe portion 33 c located away from the pump casing 12. The intake port 33a is preferably arranged at a height equal to or lower than the pumping cutoff water level LLWL, and is arranged at the same height in this embodiment. That is, the first pipe portion 33c is disposed outside the pump casing 12 so that the intake port 33a is disposed at a predetermined position.

The air supply port 33b is formed at the end of the second pipe portion 33d located closer to the pump casing 12 than the first pipe portion 33c. The first tube portion 33c and the second tube portion 33d are continuous via a folded portion 33e that is folded back in a U shape. Similar to the folded portion 30c of the first air supply pipe 30, the height of the second air supply pipe 33 from the bottom wall 3 to the inner top portion of the folded portion 33e is set to a value obtained by adding the suction head ΔHa to the maximum water level HWL. Has been.

Referring also to FIG. 4, a connection portion 33 f that is bent toward the bell mouth 16 and is connected to the inner tube 18 through the outer tube 17 is formed at the lower portion of the second tube portion 33 d. The portion through which the connecting portion 33f of the outer cylinder 17 penetrates is liquid-tightly sealed. The connecting portion 33f is located at the same height as the pumping cutoff water level LLWL and extends horizontally in the radial direction of the pump casing 12. The air supply port 33b which is the tip of the connection portion 33f is connected to the upper end of the cylindrical portion 18a of the inner cylinder 18 so as to be positioned above the air supply port 30b of the first air supply pipe 30.

Thus, the second air supply pipe 33 is arranged such that the intake port 33a is positioned at a height equal to or lower than the pumping cutoff water level LLWL, and the air supply port 33b is connected to the inner cylinder 18. Therefore, since the air can be supplied from the intake port 33a into the pump casing 12 only when the water level drops to the pumping cutoff water level LLWL, the pump 10 can be shifted from the air / water mixing operation to the air lock operation.

The air supply port 33b of the second air supply pipe 33 is disposed above the air supply port 30b and is connected to the upper end of the inner cylinder 18, so that turbulent flow and separation flow (inner It is not influenced by the water flow faster than the water flow around the cylinder 18. Therefore, it is possible to promptly shift to the pumping off operation.

In addition, since the second air supply pipe 33 includes the connection portion 33f positioned at the pumping cutoff water level and has the air supply port 33b at the tip thereof, the air flow resistance can be reduced, and the air for shutting off the pumping water is efficiently used. Can supply.

(Arrangement of each air supply piping)
Referring to FIG. 5, two first air supply pipes 30 are arranged so as to be located upstream of the pump casing 12 in the water inflow direction F. Two second air supply pipes 33 are arranged so as to be located downstream of the pump casing 12 in the inflow direction F. A total of four

air supply pipes

30 and 33 are arranged radially about the axis of the pump casing 12. The

supply pipes

30 and 33 and the pump casing 12 are preferably connected by a known connecting member (for example, a stay).

A portion of the first air supply pipe 30 above the connection portion 30d and the

pipe parts

33c and 33d of the second air supply pipe 33 are located at the position where the air suction vortex is generated, which is assumed by actual measurement or calculation. The pump casing 12 is arranged at a predetermined interval. The air suction vortex is a water flow in which the air in the water absorption tank 1 is continuously or intermittently contained in the water flowing from the water surface side toward the suction port of the bell mouth 16. This air suction vortex is generated when the water level in the water absorption tank 1 is lowered and the flow velocity on the water surface reaches a certain level. The water flow from the water surface toward the bell mouth 16 interferes with the

air supply pipes

30 and 33, so that the water flow can be eliminated before the air is sucked.

Since the pump 10 thus configured has the functions of suppressing the generation of submerged vortices, suppressing the generation of air suction vortices, and the preceding standby operation, the pump 10 does not have the first air supply pipe 30 and the second air supply pipe 33. Effective drainage at low water levels.

Specifically, in the drainage operation, even if the water level in the water absorption tank 1 becomes a vortex generation water level, the generation of air suction vortices can be suppressed by the

air supply pipes

30 and 33. Moreover, the generation of underwater vortices can be suppressed by the bell mouth 16 formed of a double trumpet tube. Therefore, vibration of the pump casing 12 due to the sucked air colliding with the impeller 25 can be prevented.

In the air-water mixing operation, the air in the water absorption tank 1 can be supplied from the first air supply pipe 30 into the pump casing 12 by the suction force of the pump 10 (dynamic pressure of the inner cylinder 18). Therefore, although the amount of water absorption from the bell mouth 16 is reduced, the flow velocity on the water surface in the water absorption tank 1 is slowed, so that the generation of air suction vortex can be suppressed and the water level that can be drained can be lowered. However, even in this case, as the water level becomes lower, the water surface eventually becomes a flow velocity at which air suction vortices are generated, but the generation of air suction vortices at this time can also be suppressed by the

air supply pipes

30 and 33.

In the air lock operation, the amount of water absorbed from the bell mouth 16 is further reduced by sucking air from the second air supply pipe 33. Therefore, drainage from the pump casing 12 to the downstream side can be stopped reliably, and the state in which the water column WC is held in the pump casing 12 can be maintained as shown in FIG. The water column WC cools the submersible bearing 23 which is a sliding component in the pump casing 12 and prevents overheating. Therefore, a standby operation in which the pump 10 is continuously driven can be realized.

As described above, in the pump 10 of the present embodiment, the first air supply pipe 30 is connected to a portion where the dynamic pressure of the inner cylinder 18 is low. Is possible. Therefore, even if it is the shallow water absorption tank 1, the pump 10 can be installed reliably. In addition, since the bell mouth 16 composed of a double trumpet pipe can suppress the generation of underwater vortices, and the four

air supply pipes

30 and 33 can suppress the generation of air suction vortices, the water level that can be drained by the pump 10 is effective. Can be lowered.

In addition, the total height of the first air supply pipe 30 and the second air supply pipe 33 is set to be higher than the maximum water level HWL plus the suction lift ΔHa, so that water is sucked up over the folded

portions

30c and 33e. It will never be done. Therefore, it is possible to prevent dust and the like from flowing into the first air supply pipe 30 and the second air supply pipe 33 and clogging at the folded

portions

30c and 33e.

Further, since the air supplied to the inner cylinder 18 is introduced into the central portion of the impeller 25, the load on the impeller 25 due to air injection can be made smaller than when it is introduced from the outer periphery. Therefore, vibration of the pump 10 due to switching of the operation state can be suppressed.

(Second Embodiment)
7 and 8 show the pump 10 of the second embodiment. In the second embodiment, the second air supply pipe 40 for switching the pump 10 from the air / water mixing operation to the air lock operation is incorporated in the vortex prevention pipe 35 for suppressing the generation of the air suction vortex. It is different from the embodiment.

Specifically, the vortex prevention pipe 35 includes an annular horizontal pipe 36 that surrounds the pump casing 12 below the drainage start water level LWL, and a straight tubular pipe that is disposed outside the pump casing 12 so as to extend in the vertical direction. And a vertical pipe 37. The second air supply pipe 40 of the second embodiment includes an intake pipe 41 arranged in the vertical pipe 37 and an air supply pipe 42 arranged between the horizontal pipe 36 and the pump casing 12.

The horizontal pipe 36 is a hollow annular pipe and is disposed on the outer periphery of the bell mouth 16. The inner diameter of the horizontal pipe 36 is substantially the same as the maximum outer diameter of the outer cylinder 17. The horizontal pipe 36 is disposed at the same height as the minimum outer diameter portion of the outer cylinder 17 so as to be positioned coaxially with the pump casing 12 and is connected by a rib (not shown). Thereby, a defined gap (flow path) is formed between the horizontal pipe 36 and the outer cylinder 17.

The vertical pipe 37 is a hollow straight pipe, and its upper end is closed liquid-tight and air-tightly by a cover 37a. The lower end of the vertical pipe 37 is connected to the horizontal pipe 36 so as to communicate with the horizontal pipe 36 spatially. In the present embodiment, four vertical pipes 37 are arranged at a predetermined interval in the circumferential direction around the pump casing 12. The upper end of the vertical pipe 37 is disposed at a position higher than the upper end (exhaust port 41c) of the intake pipe 41.

The first air supply pipe 30 of the second embodiment is arranged so as to be located outside the horizontal pipe 36. The connection portion 30d is bent at the same height as the horizontal pipe 36, and the air supply port 30b at the tip is connected to the flare portion 18b of the inner cylinder 18 as in the first embodiment.

The intake pipe 41 of the second air supply pipe 40 is a substantially straight pipe disposed in the vertical pipe 37. A bent portion 41 b that is bent outward is provided at the lower end of the intake pipe 41. The bent portion 41b passes through the horizontal pipe 36 located at the drainage cutoff water level LLWL, and the portion of the horizontal pipe 36 through which the bent portion 41b passes is liquid-tightly sealed. The air inlet 41a at the tip of the bent portion 41b is located at the same height as the drain cutoff water level LLWL and is exposed in the water absorption tank 1. The intake pipe 41 extends to a position higher than a position obtained by adding the suction lift ΔHa to the highest water level HWL, and an exhaust port 41 c at the upper end opens in the vertical pipe 37.

The air supply pipe 42 of the second air supply pipe 40 is a straight pipe, the air supply port 42 a at the inner end is connected to the cylindrical portion 17 a of the outer cylinder 17, and the connection port 42 b at the outer end is connected to the inner side of the horizontal pipe 36. Connected to the lap. In other words, the air supply pipe 42 communicates with the intake pipe 41 via the vertical pipe 37 and the horizontal pipe 36, and the second air supply pipe 40 also uses the vortex prevention pipe 35 as a flow path. Further, the air supply port 42 a of the air supply pipe 42 is connected to the outer cylinder 17 constituting the bell mouth 16 so as to be positioned above the air supply port 30 b of the first air supply pipe 30.

As shown most clearly in FIG. 8, in this embodiment, intake pipes 41 are arranged in four vertical pipes 37, respectively. Four air supply pipes 42 are arranged at equal intervals in the circumferential direction with the pump casing 12 as the center. The four air supply pipes 42 and the four vertical pipes 37 are arranged at intervals in the circumferential direction, and are configured such that the angular positions in plan view do not coincide with each other. Thus, the air flowing into the horizontal pipe 36 from the vertical pipe 37 does not flow directly to the air supply pipe 42 but always flows through the horizontal pipe 36 to the air supply pipe 42, and from the air supply pipe 42 to the inside of the bell mouth 16. Are evenly supplied. As a result, the vibration of the pump 10 due to the supply air being biased locally is suppressed.

According to the pump 10 of the second embodiment, in the drainage operation, even if the water level in the water absorption tank 1 becomes the vortex generation water level, the generation of the air suction vortex can be suppressed by the vortex prevention pipe 35. Further, in the air / water mixing operation, the air in the water absorption tank 1 can be supplied from the first air supply pipe 30 into the pump casing 12 by the suction force of the pump 10. In the air lock operation, the air sucked from the intake port 41 a is supplied into the pump casing 12 via the intake pipe 41, the vertical pipe 37, the horizontal pipe 36, and the air supply pipe 42.

In the pump 10 of the second embodiment configured as described above, the distance between the bottom wall 3 of the water absorption tank 1 and the lower end of the pump casing 12 can be secured as in the first embodiment, and the shallow water absorption tank 1 is used. Even the pump 10 can be installed. Further, since the bell mouth 16 composed of a double trumpet pipe can suppress the generation of underwater vortices, and the four vertical pipes 37 constituting the vortex prevention pipe 35 can suppress the generation of air suction vortices. The water level can be effectively lowered.

(Third embodiment)
9 and 10 show the pump 10 of the third embodiment. The third embodiment is different from the second embodiment in that the first air supply pipe 45 that switches the pump 10 from the drain operation to the air / water mixing operation is incorporated in the vortex prevention pipe 35.

Specifically, the vortex prevention pipe 35 includes one horizontal pipe 36 and four vertical pipes 37 as in the second embodiment. Among them, one vertical pipe 37 </ b> A located on the upstream side in the inflow direction F is connected to the horizontal pipe 36 so as not to spatially communicate with the inside of the horizontal pipe 36. The remaining vertical pipe 37 </ b> B is connected to the horizontal pipe 36 so as to communicate spatially with the inside of the horizontal pipe 36. And the intake pipe 41 and the supply pipe 42 which comprise the 2nd supply pipe 40 are connected to the vertical pipe 37B and the horizontal pipe 36 similarly to 2nd Embodiment.

The first air supply pipe 45 of the third embodiment has a configuration in which the vertical pipe 37A of the vortex prevention pipe 35 is also used as an intake pipe, and the air supply pipe 46 is connected to the lower end of the vertical pipe 37A.

The upper end of the vertical pipe 37A constituting the intake pipe is closed by a cover 37a as in the first embodiment. The vertical pipe 37A is provided with an intake port 37b so as to be positioned above the highest water level HWL.

The air supply pipe 46 is connected to the lower end of the vertical pipe 37 so as to be spatially continuous with the inside of the vertical pipe 37A. In the present embodiment, two air supply pipes 46 are used, and air can be supplied to the flare portion 18b of the inner cylinder 18 from different positions spaced by 45 degrees. As shown most clearly in FIG. 10, each air supply pipe 46 includes a continuous portion 46 b that extends in the circumferential direction around the rotation shaft 22, and a connection portion 46 c that is bent from the tip of the continuous portion 46 b. The connection part 46c penetrates the outer cylinder 17 similarly to each embodiment, and the air supply port 46a at the tip is connected to the flare part 18b of the inner cylinder 18.

According to the pump 10 of the third embodiment, similarly to each embodiment, the operation is switched to the drainage operation, the air / water mixing operation, and the air lock operation according to the water level in the water absorption tank 1. Therefore, the same operation and effect as each embodiment can be obtained. Further, the first air supply pipe 45 that switches from the drain operation to the air / water mixing operation and the second air supply pipe 40 that switches from the air / water mixing operation to the air lock operation suppress the generation of the air suction vortex 35. Therefore, the piping structure arranged outside the pump casing 12 can be simplified.

(Fourth embodiment)
FIG.11 and FIG.12 shows the pump 10 of 4th Embodiment. The fourth embodiment is different from the third embodiment in that the fluidity of air supplied via the vortex prevention pipe 35 is improved.

Specifically, the vortex prevention pipe 35 of the fourth embodiment includes an annular horizontal pipe 36 and four

vertical pipes

37A and 37B, as in the third embodiment. Among them, a bent portion 37 c that is bent inward in the radial direction of the pump casing 12 toward the bell mouth 16 is provided below the vertical pipes 37 </ b> A and 37 </ b> B. The inclination angle of the bent portion 37c with respect to the portion extending along the axis of the pump casing 12 is set in a range wider than 90 degrees and narrower than 180 degrees, and is set to 157.5 degrees in this embodiment.

The air supply pipe 46 of the first air supply pipe 45 is connected to the lower end of the vertical pipe 37A as in the third embodiment. The intake pipe 41 of the second air supply pipe 40 passes through the bent portion 37c of the vertical pipe 37B, and is arranged so that the intake port 41a is located at the drainage cutoff water level LLWL. The portion of the bent portion 37c that penetrates the intake pipe 41 is liquid-tightly sealed.

According to the pump 10 of the fourth embodiment, the same operations and effects as those of the third embodiment can be obtained. In addition, since the bent portions 37c are provided in the

vertical pipes

37A and 37B, the flow resistance of air to the outer cylinder 17 and the inner cylinder 18 can be reduced. Therefore, the air for switching to the air / water mixing operation and the air lock operation can be efficiently supplied.

In addition, the vertical shaft pump 10 of the present invention is not limited to the configuration of the above embodiment, and various modifications can be made.

For example, if the first

air supply pipes

30 and 45 are connected to the flare portion 18 b of the inner cylinder 18, the inner cylinder 18 of the bell mouth 16 may be configured not to protrude downward from the outer cylinder 17. Further, the

intake ports

30 a and 37 b of the

air supply pipes

30 and 45 may be arranged on the installation floor 2. The air supply pipe 42 of the second air supply pipe 40 shown in the second to fourth embodiments may be connected to the inner cylinder 18 through the outer cylinder 17, as in the first embodiment.

If the inside and outside of the pump casing 12 are always in spatial communication, the

first supply pipes

30 and 45 and the

second supply pipes

33 and 40 may be provided with orifices (throttles). Even when the vortex prevention pipe 35 is arranged, the first air supply pipe 30 and the second air supply pipe 33 shown in the first embodiment may be independently piped.

DESCRIPTION OF SYMBOLS 1 ... Water absorption tank 2 ... Installation floor 3 ... Bottom wall 4 ... Side wall 10 ... Pump 12 ... Pump casing 13 ... Pumping pipe 14 ... Straight pipe 15 ... Vane casing 15a ... Bearing casing 16 ... Bellmouth (trumpet pipe)
17 ... Outer tube 17a ... Tube portion 17b ... Flare portion 17c ... Flange portion 18 ... Inner tube 18a ... Tube portion 18b ... Flare portion 19 ... Connecting plate 19a ... Inner edge portion 19b ... Outer edge portion 19c ... Lower edge portion 19d ... Upper edge portion DESCRIPTION OF SYMBOLS 20 ... Discharge pipe | tube 21 ... Discharge elbow 22 ... Rotating shaft 23 ... Underwater bearing 25 ... Impeller 25a ... Upper end 30 ... 1st air supply piping 30a ... Intake port 30b ... Air supply port 30c ... Folding part 30d ... Connection part 33 ... 2nd air supply piping 33a ... Inlet port 33b ... Air supply port 33c ... 1st pipe part 33d ... 2nd pipe part 33e ... Folding part 33f ... Connection part 35 ... Eddy prevention pipe 36 ... Horizontal pipe 37 ... Vertical pipe 37a ... Cover 37b ... Intake port 37c ... Bent part 40 ... Second air supply pipe 41 ... Intake pipe 41a ... Intake port 41b ... Bent part 41c ... Exhaust port 42 ... Air supply pipe 42a ... Inlet port 42b ... Connection port 45 ... First Air supply pipes 46 ... air supply pipe 46a ... air supply port 46b ... continuous portion 46c ... connecting portion LWL ... drainage starting level LLWL ... drainage blocking level HWL ... High Water WC ... water column

Claims

A pump casing that is disposed in the water absorption tank so as to extend in the vertical direction, and has a trumpet pipe that sucks water in the water absorption tank at a lower end;
An impeller disposed above the trumpet pipe in the pump casing so as to be located at a predetermined drainage start water level of the water absorption tank;
A first air supply having an intake port at one end disposed outside the pump casing so as to be located above the highest water level higher than the drainage start position, and an air supply port at the other end connected to the trumpet pipe. With air piping,
The trumpet tube includes an outer cylinder, and an inner cylinder that is disposed in the outer cylinder so as to be positioned directly below the impeller and has a flare portion that gradually spreads from the upper end toward the lower end,
The air supply port of the first air supply pipe is connected to the flare portion of the inner cylinder, and the outside of the pump casing and the inside of the inner cylinder are always in spatial communication by the first air supply pipe. pump.
The vertical pump according to claim 1, wherein a diameter of a portion of the flare portion to which the first air supply pipe is connected is 1.4 times or more a diameter of an upper end opening of the inner cylinder.
The lower end of the inner cylinder protrudes from the lower end of the outer cylinder,
The vertical shaft pump according to claim 1 or 2, wherein the inner cylinder and the outer cylinder are connected by two or more connecting plates arranged radially.
The vertical shaft pump according to any one of claims 1 to 3, wherein the intake port of the first air supply pipe is disposed in the water absorption tank.
A first intake port disposed outside the pump casing so as to be located at a height equal to or lower than a pumping cutoff water level lower than the drainage start position, and a second supply port connected to the trumpet pipe. The vertical shaft pump according to any one of claims 1 to 4, comprising two air supply pipes.
The vertical pump according to claim 5, wherein the air supply port of the second air supply pipe is connected to a portion below the upper end of the inner cylinder in the trumpet pipe.
The vertical shaft pump according to claim 5 or 6, wherein the air supply port of the second air supply pipe is disposed above the air supply port of the first air supply pipe.
8. The second air supply pipe according to claim 5, wherein the second air supply pipe includes a portion that is located at the pumping cutoff water level and extends in a radial direction of the pump casing on the other end side including the air supply port. Vertical shaft pump described in 1.
An annular horizontal pipe that surrounds the lower side of the drainage start water level of the pump casing;
A vortex prevention pipe having a vertical pipe that is disposed outside the pump casing so as to extend in the vertical direction, has a lower end connected to the horizontal pipe, and a closed upper end.
The second air supply pipe is
An intake pipe disposed in the vertical pipe and having a lower end constituting the intake port exposed outside the vertical pipe;
One end is connected to the horizontal pipe, and the other end constituting the air supply port is connected to the trumpet pipe, and the vortex prevention pipe also serves as a part of the second air supply pipe The vertical shaft pump according to any one of claims 5 to 8.