JP2002089479A - Suction water tank for vertical shaft pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a top part underwater vortex and to prevent vibration and noise of a vertical shaft pump, in a suction water tank of the vertical shaft pump. SOLUTION: This suction water tank 20 for the vertical shaft pump leading water into a pump suction pipe 6 open downward has a nearly conical structure 22 disposed below the pipe 6; a nearly cylindrical water tank part 17 forming a nearly annular flow passage 16 around the nearly conical structure 22; and a straitening restriction conduit part 19 having a flow passage area which is reduced toward the downstream side from the upstream side, for generating a swirl flow 18 along the flow passage 16. A recessed communication structure for communicating a top discharge hole 24 bored in a top part with at least one inflow hole 23 bored in a lower part of the nearly conical structure 22 is formed inside the nearly conical structure 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical pump suction water tank provided at a vertical pump station, and more particularly to a vertical pump suction water tank for guiding water to a pump suction pipe opened downward.

[0002]

2. Description of the Related Art In recent years, large rivers in various places have drainage pumping stations (hereinafter referred to as “stations” as appropriate) for urgent drainage to the sea or bypass waterways in order to prevent flooding of river basins during heavy rainfall. Is being built.

[0003] This is achieved by introducing water from a river on the rising side to a suction water tank of the plant, for example, through a pump suction pipe provided with a bell mouth-shaped suction port opened downward in the suction water tank. The water is pumped by a vertical pump into a discharge water tank located at a high head (head), and is discharged to an appropriate drainage path.

However, when the vertical pump is operated to start suction from the suction port in the suction tank, as the flow velocity increases, near the suction port, a vortex linked to the turbulence of the flow is directed toward the bottom or water surface of the water tank. More likely to occur.

At the center of these vortices, the water pressure becomes extremely low, so that cavities are generated, and they become vortices called underwater vortices or air suction vortices, which adversely affect the vertical pump such as vibration and noise.

In general, these vortices are more likely to occur as the suction flow velocity at the suction port and the flow velocity at the upstream of the suction water tank increase. Therefore, to increase the suction efficiency by making the suction water tank smaller to increase the suction flow velocity. Since the generation of vortices would be promoted, the suction water tank had to be set large, and there was a problem that the space saving of the plant could not be expected.

Therefore, conventionally, a substantially conical structure (hereinafter referred to as a substantially conical structure) is provided on the bottom surface of the suction tank below the suction port, so that the submersible vortex generated from the suction port of the suction pipe toward the bottom surface of the suction tank. In addition, a method has been adopted in which the occurrence of air vortices is prevented from occurring upward from the suction port of the suction pipe by providing a ceiling in the suction water tank.

However, this substantially conical structure has a problem that when the flow in the suction water tank flows uniformly in the width direction, a new separation vortex is generated behind the conical structure. To cope with this, Japanese Patent Laid-Open No.
As described in JP-A-148498, in a suction water tank of a vertical shaft pump that guides water into a pump suction pipe that opens downward, a substantially cylindrical water tank part that forms a substantially annular flow path around a substantially conical structure, A rectifying throttle channel connected to the upstream side of the substantially cylindrical water tank so as to reduce the flow area from the side toward the bottom and to generate a swirl flow along the substantially annular flow path in the substantially cylindrical water tank. (A so-called spiral-shaped aquarium) has been proposed. With such a configuration, a swirling flow is always generated in a constant direction around the substantially conical structure in the suction water tank, regardless of the presence or absence of the flow deviation in the upstream water channel and the direction of the deviation. Prevent occurrence.

[0009]

However, the above prior art has the following problems. That is, even when the substantially conical structure is installed in the spiral water tank as described above, if the swirling flow is generated to some extent due to the increase in the flow velocity, the inside of the pump suction pipe from the top of the substantially conical structure and further to the pump A new coaxial underwater vortex (hereinafter referred to as a top underwater vortex) is generated across the impeller. Therefore, large vibration and noise are generated in the pump suction pipe and the impeller. These hinder the further increase in flow velocity, that is, the space saving of the suction water tank.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a suction pump for a vertical shaft pump which prevents the generation of a vortex at the top and prevents vibration and noise of the vertical shaft pump.

[0011]

(1) In order to achieve the above object, the present invention relates to a suction water tank of a vertical shaft pump for guiding water into a pump suction pipe opened downward, wherein the pump is provided below the pump suction pipe. It is assumed that a substantially conical structure is provided, and a concave communication structure for communicating from a lower portion to a top portion is formed on a side surface or inside the substantially conical structure.

When a top water vortex is generated between the top of the substantially conical structure and the pump impeller, the water pressure at the center of the top water vortex is considerably low. There will be a large pressure difference between the top of the substantially conical structure and the lower portion of the substantially conical structure outside the top water vortex and near the bottom of the suction tank. In the present invention, by forming the concave communication structure that communicates from the lower part to the top part, a water flow is generated from the lower part to the top part of the substantially conical structure through the concave communication structure,
It works so that the water near the bottom of the suction water tank flows into the center of the top water vortex. As a result, since the center cavity of the top water vortex is filled, the generation of the top water vortex is prevented.

At this time, as the flow velocity in the suction water tank increases, the swirling flow around the substantially conical structure and the top water vortex increase, and the pressure at the center of the top water vortex further decreases. Since the pressure difference between the top of the substantially conical structure and the lower part near the bottom of the water tank also increases, more water flows into the center of the top water vortex, and the top water vortex prevention effect is maintained.

Further, since the concave communication structure is formed on the side surface or inside of the substantially conical structure, the swirling flow flowing around the substantially conical structure has no disturbance (for example, local vortex). Water can be smoothly circulated from the lower portion to the top without causing generation.

(2) In the above (1), preferably,
A substantially cylindrical water tank that forms a substantially annular flow path around the substantially conical structure, and a flow path area that decreases from an upstream side to a downstream side, and the substantially annular flow path in the substantially cylindrical water tank part. And a rectifying throttle channel connected upstream of the substantially cylindrical water tank so as to generate a swirling flow along the flow path.

[0016] Thus, a stable swirling flow can be generated in a constant direction around the pump suction pipe and the substantially conical structure regardless of the presence or absence of the flow deviation in the upstream water channel and the direction of the deviation. In addition, the generation of separation vortex is prevented, and the pressure difference between the top and the lower part of the substantially conical structure is also stabilized, so that the flow of water therebetween can be maintained.

(3) In the above (1) or (2), preferably, the concave communication structure comprises at least one inflow hole drilled below the substantially conical structure and at least one discharge hole drilled at the top. It is configured to communicate inside the substantially conical structure.

(4) In the above (1) or (2), preferably, the concave communication structure is a communication groove provided at least one from a lower portion to a top portion on a side surface of the substantially conical structure. .

As a result, since the processing of the concave communication structure is easy, the manufacturing cost can be reduced.

(5) In any one of the above (1) to (4), preferably, the suction port of the pump suction pipe is formed in a bell mouth shape.

Thus, the swirling flow around the pump suction pipe and the substantially conical structure can be smoothly sucked from the vicinity of the suction port.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. Hereinafter, the suction tank of the vertical shaft pump according to the first embodiment of the present invention will be described with reference to FIGS.

FIG. 1A is a vertical sectional view in the water flow direction of the suction water tank of the vertical shaft pump according to the present embodiment, and FIG.
FIG. 2 is a plan view as seen from an II plane in FIG. 1 (a) and 1 (b), a suction water tank 20 into which water such as a river flows in from a water conveyance path (not shown), and a discharge water tank 3 located at a head higher than the suction water tank 20.
In the vicinity of the downstream closed end (the right end in the figure) of the suction water tank 20, the pump suction port 4 at the lower end is opened toward the lower bottom surface, and the upper part thereof is bent substantially horizontally and horizontally to discharge the pump discharge at the opening. Exit 5
A pump suction pipe 6 connected to the discharge water tank 3, a substantially conical structure 22 installed on the bottom surface of the suction water tank 20 below the pump suction port 4, and a plurality of blades 7a arranged inside the pump suction port 4. , A pump impeller shaft 8 provided through the pump suction pipe 6 and having the pump impeller 7 fixed to the tip thereof, and a clutch 9 located above the bent portion of the pump suction pipe 6. And a drive unit 10 having a pump motor 10a connected to the impeller shaft 8 through the drive unit 10.

The suction water tank 20 has a substantially cylindrical water tank portion 17 that forms a substantially annular flow path 16 around the substantially conical structure 13, and has a substantially cylindrical flow path area whose flow path area decreases from the upstream side to the lower side. A vortex-type suction water tank having a rectifying throttle water passage 19 connected upstream of the substantially cylindrical water tank 17 so as to generate a swirling flow 18 along the substantially annular flow path 16 in the water tank 17. A ceiling 20b is provided above the periphery of the pump inlet 4 at a height lower than the water surface W and filled with water.

The pump suction port 4 is located in the water filling the suction water tank 2 and guides water from the suction water tank 20 into the pump suction pipe 6, and is formed in a bell mouth shape which spreads in a curved line. The pump prime mover 10a is, for example, a prime mover such as a gas turbine, and its output shaft 10b is connected to the impeller shaft 8 via, for example, a disk-shaped clutch 9 for connecting / disconnecting the driving force. The pump discharge port 5 is connected to the discharge water tank 3 so as to be immersed in water filling the discharge water tank 3.

The substantially conical structure 22 is radially perforated at a plurality of locations in the circumferential direction at a lower portion located near the bottom surface 20a of the suction water tank 20, which is an installation surface, and has a diameter inside the substantially conical structure 22. A plurality of (four in the figure) inflow holes 23 extending linearly to the center in the direction and communicating with each other, and the inflow holes 23 are drilled in a substantially vertical direction from the top of the substantially conical structure 22.
And one apex discharge hole 24 communicating with it.

In the above description, the top discharge hole 24 constitutes the discharge hole described in each claim, and the inflow hole 23 and the top discharge hole 24 form the concave communication structure described in each claim. Make up.

Next, the operation of the present embodiment will be described. First, the background principle of the present invention will be described with reference to FIGS. Hereinafter, in FIGS. 2 to 7, the same reference numerals as those in FIG. 1 indicate the same parts.

FIG. 2 is a longitudinal sectional view showing a structure of a suction water tank of a general vertical shaft pump. In FIG. 2, the suction water tank 2 has a substantially rectangular shape and extends in the left direction in the figure. As in FIG. 1A, the pump suction port 4 is located in the water filling the suction water tank 2 so that water can be guided from the suction water tank 2 into the pump suction pipe 6.

In the above configuration, when the pump impeller 7 is driven to rotate to start pumping, a horizontal sectional view taken along the line III-III in FIGS. 3 (a) and 3 (a), which is an enlarged view of a main part of FIG. As shown in FIG. 3B, the water around the pump suction port 4 is sucked into the pump suction pipe 6 at a flow velocity Vb in conjunction with the rotation of the pump impeller 7, and the water in the suction water tank 2 is Is the flow velocity Vs from the left side in the figure toward the pump suction pipe 6.
Flows in

As the flow velocity Vb or Vs increases, a vortex is generated in the pump suction port 4 from the bottom surface 2a of the suction water tank 2 or from the water surface W, and the flow velocity Vb or Vs further increases. Since the pressure at the center of each vortex becomes extremely low, the vortex becomes a cavity and becomes an air suction vortex 11 and a water vortex 12 as shown in the figure.

As described above, the vortex generated in the pump suction port 4 with its center being hollow causes large vibrations and noise to the pump suction port 4 and the pump impeller 7 rotating inside the pump suction port 4. For this reason, Vb and Vs are limited. As a result, in order to secure the same flow rate, it is necessary to increase the width dimension, which hinders space saving of the water tank 2 itself.

To solve this, the pump suction port 4
It is conceivable to provide some configuration around the periphery to prevent the generation of vortices. FIG. 4 is a sectional view in the water flow direction in the case where a ceiling and a substantially conical structure are provided to prevent the occurrence of the air suction vortex 11 and the underwater vortex 12, respectively. As a configuration, a substantially conical structure 13 is installed on the bottom surface of the suction water tank 2 below the pump suction port 4, and as an effective configuration for preventing the generation of the air suction vortex 11 above the suction water tank 2 around the pump suction port 4. Water surface W
The ceiling 2b is provided at a lower height to be filled with water.

The installation of the ceiling 2b and the substantially conical structure 13 can prevent the occurrence of the air suction vortex 11 and the underwater vortex 12, respectively. As shown in FIG. 5A, which is an enlarged view of a main part of FIG. 4, and FIG. 5B, which is a horizontal sectional view taken along the line VV in FIG. As a result, the flow of water is separated, and separation vortices 14 are generated at two places on the left and right behind the substantially conical structure 13. This is remarkable especially when the flow in the suction water tank 2 flows uniformly in the width direction.

In order to solve this, a substantially conical structure 13 is used.
It is conceivable that the flow at the time of inflow is not uniform in the width direction and is biased to one side.

FIG. 6A is a cross-sectional view in the water flow direction when a spiral-wound water tank is used to prevent the separation vortex 14, and FIG. 6B is a cross-sectional view taken along the line VI-VI in FIG. FIG.

6 (a) and 6 (b), a spirally wound suction water tank 20 having a substantially cylindrical water tank portion 17 and a rectifying throttle water passage portion 19 connected upstream of the substantially cylindrical water tank portion 17 is shown. , A substantially conical structure 13 is provided. With such a configuration, regardless of whether or not the flow is biased in the upstream rectifying throttle channel portion 19 and the direction of the bias, the flow is always stabilized in a constant direction around the substantially conical structure 13 in the substantially cylindrical water tank portion 17. The swirling flow 18 is generated to prevent the generation of the separation vortex 14 described above.

On the other hand, if the swirling flow 18 becomes stronger due to a further increase in the flow velocity Vs, as shown in FIGS. There is a possibility that a coaxial top water vortex 15 is newly generated from the inside to the inside of the pump suction pipe 6 and further to the pump impeller 7.

Therefore, based on the above, in the suction water tank 20 of the vertical shaft pump according to the present embodiment shown in FIG. 1, the inflow hole 23 and the apex discharge hole for communicating the lower part and the top part of the substantially conical structure 22 as described above. By providing the inside 24, generation of the top water vortex 15 is prevented.

That is, in FIG. 1, when the strong swirling flow 18 is generated along the substantially annular flow path 16 around the substantially conical structure 22 and the top water vortex 15 is generated as described above, the top water vortex 15 is generated. The water pressure at the center of the bottom water vortex 15 is considerably low, so that the top of the substantially conical structure 22 located at the center of the top water vortex 15 and the substantially cone outside the top water vortex 15 and close to the bottom surface of the suction water tank 20 There is a large pressure difference between the lower part of the structure 22 and the lower part. Therefore, by providing the inflow hole 23 and the apex discharge hole 24 as described above, a water flow from the lower portion to the top of the substantially conical structure 22 is generated through the inflow hole 23 and the apex discharge hole 24, and the suction water tank 20 is formed. Water near the bottom surface 20a flows into the center of the top water vortex 15.
As a result, the center cavity of the top water vortex 15 is filled, so that the generation of the top water vortex 15 is prevented.

At this time, the flow velocity Vs in the suction water tank 20
As FIG. 1 (see FIG. 1) increases, the swirling flow 18 around the substantially conical structure 22 and the top water vortex 15 become stronger, and the pressure at the center of the top water vortex 15 is further reduced.
The pressure difference between the top of the substantially conical structure 22 located at the center of the bottom and the lower part near the bottom surface 20a of the suction water tank 20 also increases, so that more water flows into the center of the top water vortex 15, and The effect of preventing the underwater vortex 15 is maintained.

Since the communication structure formed by the inflow hole 23 and the apex discharge hole 24 is formed inside the substantially conical structure 22, the swirling flow 18 flowing around the substantially conical structure 22 is formed.
For example, water can be smoothly circulated from the lower part to the top without causing the occurrence of disturbance such as local vortex.

Further, since the pump suction port 4 is formed in a bell mouth shape, the pump suction pipe 6 and the swirling flow 18 around the substantially conical structure 22 can be sucked smoothly from the vicinity of the pump suction port 4. it can.

In the substantially conical structure 22 according to the present invention, the configuration of the inflow hole 23 is not limited to a round hole having the same vertical and horizontal diameters as shown in FIG. May be formed to have a larger diameter in the circumferential direction.
As a result, more water can flow in from the lower part where the pressure is high and can be discharged to the center of the vortex, so that the generation of the top water vortex 15 can be more reliably prevented.

Further, the shape of the flow passage of the inflow hole 23 inside the substantially conical structure 22 is not limited to a linear shape extending from the circumference to the central point as shown in FIG. It may be configured to communicate and gather toward the center point of the substantially conical structure 22 in a spiral shape inclined in the same direction as the above. As a result, more water can smoothly flow into the inflow hole 23 by utilizing the dynamic energy of the swirling flow, and the water can be discharged to the center of the top water vortex 15 at a higher water pressure.

In the first embodiment of the present invention, the inflow holes 23 are provided at a plurality of locations (four locations in the figure) in the circumferential direction of the substantially conical structure 22, but the invention is not limited to this. A substantially conical structure 22 if at least one is provided
The water can be transferred from the lower part to the top and discharged to the center of the top water vortex 15, so that the generation of the top water vortex 15 can be prevented.

Next, a suction tank according to a second embodiment of the present invention will be described with reference to FIGS. 8 (a) and 8 (b). In the present embodiment, the communication structure provided inside the substantially conical structure 22 in the above-described first embodiment of the present invention further includes a plurality of discharge holes circumferentially extending laterally at the top near the apex. Perforated above.

FIG. 8 (a) is a vertical sectional view in the water flow direction of the suction water tank of the vertical shaft pump according to the present embodiment, and FIG. 8 (b) is a plan view taken along the line VIII-VIII in FIG. 8 (a). It is. In FIGS. 8A and 8B, FIG.
1A and 1B denote the same parts, and a description thereof will not be repeated.

8A and 8B, the suction water tank 20 is provided with a substantially conical structure 22A, and the substantially conical structure 22A has a plurality of inflow holes 23 described above.
And a plurality of (four in the figure) reaching the side near the apex of the inflow hole 23, provided diagonally upward from the top of the apex discharge hole 24 and the apex discharge hole 24 arranged in a substantially vertical direction. And a circumferential discharge hole 25.

According to the present embodiment, as in the first embodiment, the generation of the top water vortex 15 is prevented.

In addition to the above, according to the communication structure of the present embodiment, even if the center of the vortex in contact with the top of the substantially conical structure 22A moves slightly, a plurality of circumferential discharges provided at four locations in the circumferential direction of the top are provided. Since the possibility of contact with any one of the holes 25 increases, there is an effect that the effect of preventing the generation of eddies becomes more reliable.

Note that in the second embodiment,
The inflow holes 23 and the circumferential discharge holes 25 are provided at a plurality of locations (four locations in the figure) at the lower portion and the top portion of the substantially conical structure 22A, respectively, but are not limited thereto. If one is provided, the same effect can be obtained.

Next, a suction tank of a vertical shaft pump according to a third embodiment of the present invention will be described with reference to FIGS. 9 (a) and 9 (b). In the present embodiment, the communication structure of the substantially conical structure 22 in the above-described first embodiment of the present invention is provided with holes (flow-in holes 23 and apex discharge holes 2) through which water flows from the lower part to the upper part.
Instead of being provided inside as 4), a groove through which water can flow from the lower portion to the top portion on the side surface of the substantially conical structure is provided.

FIG. 9 (a) is a vertical sectional view in the water flow direction of the suction water tank of the vertical shaft pump according to the present embodiment, and FIG. 9 (b) is a plan view taken along the line IX-IX in FIG. 9 (a). FIG. In FIGS. 9A and 9B, the same reference numerals as those in FIGS. 1A and 1B denote the same parts, and a description thereof will not be repeated.

9 (a) and 9 (b), the suction water tank 20 is provided with a substantially conical structure 22B, and the substantially conical structure 22B has a bottom outer edge located at the lowest position. A plurality of (four in the figure) communication grooves 26 are provided on the side surface in a straight line so as to reach the apex.

In the above, the communication groove 26 constitutes at least one communication groove provided from the lower part to the top part on the side surface of the substantially conical structure described in claim 4.

According to the present embodiment, the water flows from the lower portion of the substantially conical structure 22B to the top along the communication groove 26 on the same principle as that of the first embodiment, and The flow of water into the central cavity of the underwater vortex 15 prevents the top water vortex 15 from being generated.

In addition to the above, in the case of the present embodiment, it is only necessary to form a groove on the side surface of the substantially conical structure 22B.
Since the configuration is much simpler than the configuration in which the communication holes are provided inside as in the first and second embodiments, there is an advantage that the manufacturing cost can be greatly reduced. This is particularly effective when installed in the suction water tank of a large vertical pump.

In the third embodiment, the communication grooves 26 are provided at a plurality of positions (four in the figure) in the circumferential direction of the substantially conical structure 22B, but the present invention is not limited to this. It is sufficient if at least one is provided on the circumference, and in such a case, a similar effect is obtained.

Next, a suction tank according to a fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, as the communication structure, there is provided a cutout that is formed linearly from the bottom to the top so as to divide the entire substantially conical structure in the circumferential direction.

FIG. 10 (a) is a vertical sectional view in the water flow direction of the suction water tank of the vertical shaft pump according to this embodiment.
FIG. 10B is a plan view as viewed from an arrow X-X in FIG. In these FIGS. 10A and 10B,
9A and 9B denote the same parts, and a description thereof will not be repeated.

In FIG. 10A and FIG. 10B,
The suction water tank 20 is provided with a substantially conical structure 22C. The plurality of substantially conical structures 22C linearly extend from the bottom surface of the suction water tank 20 to the apex of the substantially conical structure 22C (in FIG. 4 provided at a position orthogonal to the direction
) Through the substantially conical structure 22C from the central axis.
It is arranged so as to divide the whole in the circumferential direction (in this case, to divide into four).

According to the present embodiment, the above-mentioned first to third
Similarly to the embodiment, the water flows from the lower part of the substantially conical structure 22C to the top through the cut-through 27, and flows into the central cavity of the top water vortex 15, whereby the top water vortex 15 is formed. Is prevented from occurring.

In addition to the above, in the case of the present embodiment, the substantially conical structure 22C divided into several pieces in the circumferential direction from the center may be installed with an appropriate gap therebetween. Since the configuration is much simpler than the configuration in which the communication holes are provided inside as in the first and second embodiments, there is an advantage that the manufacturing cost can be greatly reduced. This is particularly effective when installed in the suction tank of a large vertical pump.

In the fourth embodiment, a plurality of cutouts 27 (four in the figure) are provided in the circumferential direction of the substantially conical structure 22C. However, the present invention is not limited to this, and at least the cutouts 27 are provided in the circumferential direction. It is sufficient if one is provided, and in such a case, a similar effect is obtained.

In the above description, the present invention has been described by taking as an example an embodiment in which the present invention is applied to a spiral-wound suction water tank 20 in which a rectifying throttle water passage section 19 is connected upstream of a substantially cylindrical water tank section 17. It is not limited to. That is, the generation of the above-mentioned top water vortex 15 is caused by the substantially conical structure 13.
The present invention is not limited to the case where is installed in the above-mentioned vortex-shaped suction water tank 20. For example, even in the case of a rectangular suction water tank 2 as shown in FIGS. A large drift occurs in the width direction, and a strong swirling flow 18 is generated around the substantially conical structure 13 as shown in FIGS. In such a case, similar effects can be obtained by providing the above-described communication structure in the substantially conical structure 13.

[0067]

According to the present invention, the water near the bottom of the suction tank is poured into the center of the top water vortex by utilizing the large pressure difference generated between the center of the top water vortex and the vicinity of the bottom of the suction tank. By satisfying the above condition, it is possible to prevent the generation of a vortex in the top water.

As a result, the vibration and noise of the vertical shaft pump caused by the vortex can be prevented, so that the water flow in the suction water tank can be further increased, that is, the space of the suction water tank can be reduced, and the entire vertical shaft pump station can be saved. Construction costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view in a water flow direction of a suction water tank of a vertical shaft pump according to a first embodiment of the present invention, and a plan view seen from an II plane in FIG. 1 (a).

FIG. 2 is a vertical cross-sectional view in a water flow direction of a suction water tank of a general vertical shaft pump.

FIG. 3 is an enlarged vertical sectional view in a water flow direction of a suction water tank, which is a main part of FIG. 2, and a plan view seen from an arrow III-III in FIG. 3 (a).

FIG. 4 is a sectional view in a water flow direction of a suction water tank provided with a ceiling and a substantially conical structure for preventing generation of an air suction vortex and a water vortex.

FIG. 5 is a sectional view in a water flow direction for explaining a state in which a separation vortex is generated in a suction water tank having a substantially conical structure, and FIG.
FIG. 5 is a plan view seen from an arrow VV.

FIG. 6 is a sectional view taken along a water flow direction of a suction water tank of a spiral shape for preventing a separation vortex, and a plan view seen from a section taken along line VI-VI in FIG. 6 (a).

FIG. 7 is a cross-sectional view in a water flow direction for explaining a state in which a top water vortex is generated in a spiral-shaped suction water tank in which a substantially conical structure is installed, and a plan view seen from an arrow VII-VII in FIG. is there.

FIG. 8 is a vertical sectional view in a water flow direction of a suction water tank of a vertical shaft pump according to a second embodiment of the present invention, and VIII-VIII in FIG. 8 (a).
FIG. 3 is a plan view as viewed from an arrow direction.

FIG. 9 is a longitudinal sectional view in a water flow direction of a suction water tank of a vertical shaft pump according to a third embodiment of the present invention, and a plan view seen from an IX-IX plane in FIG.

FIG. 10 is a vertical sectional view in a water flow direction of a suction water tank of a vertical shaft pump according to a fourth embodiment of the present invention, and is a plan view seen from a plane XX in FIG. 10 (a).

11 is a sectional view in the water flow direction for explaining a state in which a top water vortex is generated in the rectangular suction water tank shown in FIG. 5, and FIG.
(A) It is an arrow plan view seen from the middle XI-XI plane.

[Explanation of symbols]

 2 Suction Water Tank 4 Pump Suction Port (Suction Port) 6 Pump Suction Pipe 16 Substantially Annular Channel 17 Substantially Cylindrical Water Tank 18 Swirling Flow 19 Rectifying Restriction Water Channel 20 Suction Water Tank 22 Substantially Conical Structure 22A-C Substantially Conical Structure 23 Inlet hole (concave communication structure) 24 Apex discharge hole (concave communication structure, discharge hole) 25 Circumferential discharge hole (concave communication structure, discharge hole) 26 communication groove (concave communication structure) 27 Cut-through (concave communication structure)

Continued on the front page F term (reference) 2D063 AA03 DC04 3H034 AA01 AA20 BB01 BB08 BB12 BB16 CC07 DD02 DD28 EE06 EE08 EE12

Claims (5)

[Claims] 1. A suction water tank of a vertical shaft pump for guiding water into a pump suction pipe opened downward, wherein a substantially conical structure is provided below the pump suction pipe, and a side surface or an inside of the substantially conical structure is provided with a lower part. A suction tank for a vertical shaft pump, wherein a concave communication structure for communicating from a part to a top part is formed. 2. The suction water tank of a vertical shaft pump according to claim 1, wherein a substantially cylindrical water tank portion forming a substantially annular flow path around the substantially conical structure, and a flow passage area from an upstream side to a downstream side. And a rectifying throttle channel connected to the upstream side of the substantially cylindrical water tank so as to generate a swirling flow along the substantially annular flow path in the substantially cylindrical water tank. A vertical suction pump suction tank. 3. The suction water tank of a vertical shaft pump according to claim 1, wherein said concave communication structure has at least one inflow hole formed in a lower portion of said substantially conical structure and a discharge hole formed in a top portion thereof. A suction water tank of a vertical shaft pump, wherein the suction water tank is configured to communicate inside the substantially conical structure. 4. The suction water tank of a vertical shaft pump according to claim 1, wherein the concave communication structure is a communication groove provided at least one from a lower portion to a top portion on a side surface of the substantially conical structure. The vertical pump suction water tank. 5. A suction tank for a vertical shaft pump according to claim 1, wherein the suction port of the pump suction pipe is formed in a bell mouth shape. .