Pump

Abstract

To suppress suction of an air suction vortex.SOLUTION: A pump 10 includes a casing 11 extending upward from the vicinity of a bottom of a water tank 1 and having a suction port 11a for sucking water in the water tank 1 at a lower end thereof, a gutter-shaped horizontal member 31 extending along a circumferential direction of the casing 11 on an outer peripheral side of the suction port 11a and opened to an upper side and a center side of the casing 11, and a gutter-shaped vertical member 32 extending upward from the horizontal member 31 and opened to an upstream side in a water flow direction at least at an upper end thereof.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pump. [Background technology]

[0002] Patent Document 1 discloses a vertical shaft pump with a casing that extends upward from near the bottom of a water tank. Water flows from the water tank into the casing through a suction port at the bottom of the casing. When the water level is low, an air-sucking vortex is generated from the water surface toward the suction port. When the air-sucking vortex flows into the casing, it reduces the pumping efficiency.

[0003] Therefore, this vertical pump is equipped with a semi-cylinder surrounding the suction port and multiple vertical rods and ribs arranged on the outside of the casing. These components are expected to divert the air suction vortex or destroy the air suction vortex itself. To achieve this, it is necessary to accurately arrange the vertical ribs and rods at the position where the air suction vortex occurs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7339017 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the shape of the tank varies greatly from one pumping station to another, mainly due to the unique topographical conditions of each pumping station. During the manufacturing stage of the pump, it is difficult to accurately predict the flow field in the tank of the new installation and to accurately identify the location where the air entrainment vortex occurs. Therefore, it is difficult to appropriately arrange the longitudinal ribs and longitudinal bars to achieve the expected operation.

[0006] An object of the present invention is to suppress the intake of air entrainment vortexes. [Means for solving the problem]

[0007] One aspect of the present invention provides a pump comprising a casing extending upward from near the bottom of a tank and having an inlet at its lower end for drawing in water from the tank, a gutter-shaped horizontal member extending circumferentially of the casing on the outer periphery of a portion of the casing that defines the inlet and opening toward the upper side and center of the casing, and a gutter-shaped vertical member extending upward from the horizontal member and opening at least at its upper end toward the upstream side in the direction of water flow.

[0008] According to the above configuration, the water flow on the water surface in the tank is received by the vertical member. The water flow is directed downward while being guided by the vertical member so as to be drawn into the suction port by the action of the pump. When the water flow reaches the vicinity of the lower end of the vertical member, it is received by the horizontal member that is open on the upper side. The water flow is guided by the horizontal member and directed toward the center. Since the horizontal member is disposed on the outer periphery of the suction port, this water flow directed toward the center is sucked into the suction port. Even if an air-sucking vortex occurs around the vertical member, this water flow prevents the air-sucking vortex from reaching the suction port. Therefore, the suction of the air-sucking vortex can be suppressed.

[0009] The vertical member may be wider toward the bottom.

[0010] According to the above-mentioned configuration, the water flow is guided by the vertical member and directed downward and simultaneously in the circumferential direction, so that even if the position at which the air-sucking vortex occurs is somewhat shifted in the circumferential direction from the position of the upper end of the vertical member, the water flow can hinder the intake of the air-sucking vortex.

[0011] The lower end of the vertical member may be arcuate with the same diameter as the upper edge of the horizontal member and may be fixed to the upper edge of the horizontal member.

[0012] According to the above-mentioned configuration, the horizontal member and the vertical member are integrated into one structure. Also, the water flow guided to the lower end of the vertical member smoothly flows into the inner side of the horizontal member. Therefore, the water flow from the water surface to the suction port can be realized.

[0013] The lower end of the cross member may be located below the suction opening.

[0014] According to the above configuration, the water flow from the horizontal member toward the center tends to flow upward through the suction port.

[0015] The upper end of the vertical member may be located above the lowest water level that can be drained.

[0016] With the above configuration, even when the water level in the tank is at its lowest level, the water flow on the water surface can be received by the upper end of the vertical member, thereby suppressing the intake of air-entraining vortexes according to the above principle. Effect of the Invention

[0017] According to the present invention, the intake of air-sucking vortexes can be suppressed. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a vertical cross-sectional view of the pump according to the embodiment. [Diagram 2] FIG. 2 is a plan view of a water tank to which the pump according to the embodiment is applied. [Diagram 3] FIG. [Figure 4] 1 is a graph showing the radius of a vertical member versus the vertical distance from the top end of the vertical member. [Figure 5A] FIG. [Figure 5B] FIG. [Figure 5C] FIG. [Figure 6A] Side view of upper fixing member [Figure 6B] FIG. [Figure 7] FIG. 13 is a plan view of a water tank when a vortex suppression structure is provided around the entire periphery of the pump according to the embodiment. [Figure 8] FIG. 11 is a vertical cross-sectional view of a lower fixing member according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment will be described with reference to the drawings. Note that the same or corresponding elements are designated by the same reference numerals throughout the drawings, and detailed description thereof will be omitted.

[0020] Referring to Fig. 1, pump 10 is introduced into a pumping station including a water tank 1 that communicates with a waterway (not shown). The upper side of water tank 1 is closed by a floor 2 of the pumping station. Pump 10 is inserted into water tank 1 through an opening 2a formed in floor 2. Pump 10 according to this embodiment is a vertical shaft pump that is fixed to floor 2 in an orientation extending in the vertical direction.

[0021] The pumping station is provided, for example, in a drainage pumping station or a pumping station, and the waterway includes, for example, a drainage channel for storm water or sewage, a canal, and the like. The water tank 1 includes a common part continuing from the waterway and a plurality of branch parts continuing from the common part. FIG. 1 and FIG. 2 show one of the plurality of branch parts as the water tank 1. In general, the pump 10 corresponds to the branch part one-to-one. The water tank 1 (particularly, the branch part) has a bottom surface 1a, a pair of side surfaces 1b, and a dead-end end surface 1c. Water flows from the waterway into the water tank 1 and is stored in the water tank 1. In the water tank 1, the water flows into each branch part via the common part, and is pumped up by the pump 10 in each branch part. Roughly speaking, in each branch part, a water flow F is formed near the water surface toward the end surface 1c along the extension direction of the pair of side surfaces 1b. The water level can fluctuate in the vertical direction with the lowest water level LWL that can be discharged by the pump 10 as the lower limit. FIG. 1 shows this minimum water level LWL as an example of the water level in the water tank 1.

[0022] The pump 10 comprises a casing 11 and a rotating shaft 21 .

[0023] Referring to FIG. 1, the casing 11 extends upward from near the bottom of the water tank 1. The casing 11 is constructed by sequentially connecting a plurality of casing members including a trumpet tube 12, a pump casing 13, a water lifting pipe 14, a hanging pipe 15, and a discharge pipe 16 in this order from below. Each casing member is cylindrical or tubular with both ends open, and is coaxial with each other. The upper end flange 15a of the hanging pipe 15 has a larger diameter than the other flanges, and is fixed to the periphery of the opening 2a. The lower part of the casing 11 is accommodated in the water tank 1 like the trumpet tube 12, while the upper part of the casing 11 is arranged outside the water tank 1 like the discharge pipe 16. The trumpet tube 12 is expanded toward the lower end. The lower end opening of the trumpet tube 12, i.e., the lower end opening of the casing 11 as a whole, serves as the suction port 11a of the casing 11. The suction port 11a is closely opposed to the bottom surface 1a of the water tank 1. The discharge pipe 16 is elbow-shaped, and its tip opening is directed laterally above the floor 2. The tip opening of the discharge pipe 16, i.e., the upper end opening of the casing 11 as a whole, serves as the discharge port 11b of the casing 11.

[0024] The rotating shaft 21 extends vertically within the casing 11. The lower end of the rotating shaft 21 is adjacent to the upper end opening of the trumpet tube 12 or the lower end opening of the pump casing 13 in the vertical direction. The impeller 22 is fixed to the lower end of the rotating shaft 21 and housed within the pump casing 13. The rotating shaft 21 is rotatably supported by a plurality of bearings 23 arranged at intervals in the vertical direction within the casing 11. The rotating shaft 21 is coaxial with the trumpet tube 12, the pump casing 13, the lifting pipe 14, and the suspension pipe 15. While the central axis of the casing 11 is bent by the discharge pipe 16, the axis of the rotating shaft 21 extends linearly as it is. The upper end of the rotating shaft 21 penetrates the wall of the discharge pipe 16 and is connected to an actuator (not shown) arranged outside the casing 11. The actuator is, for example, an electric motor, and drives the rotating shaft 21 to rotate.

[0025] When the rotating shaft 21 is driven to rotate, the impeller 22 rotates integrally with the rotating shaft 21. Accordingly, water in the water tank 1 flows into the casing 11 from below through the suction port 11a. The water is pumped upward within the casing 11 and flows out of the casing 11 through the discharge port 11b. The discharge port 11b can be connected to a drainage pipe (not shown) of the pumping station.

[0026] A Karman vortex may occur downstream of the pump 10. When the water level in the water tank 1 is low, the Karman vortex may develop into an air-sucking vortex E. The air-sucking vortex E occurs from the water surface toward the suction port 11a. If air is introduced into the casing 11 together with the water, it will result in a decrease in pumping efficiency.

[0027] Therefore, the pump 10 is equipped with a vortex suppression structure 30 that suppresses the air suction vortex E. Here, "suppression" not only includes destroying the air suction vortex E itself and reducing the momentum of the air suction vortex E, but also includes blocking the flow of the air suction vortex E from the water surface to the suction port 11a, thereby preventing the air suction vortex E from reaching the suction port 11a. The vortex suppression structure 30 according to this embodiment provides both the former effect (weakening the air suction vortex E) and the latter effect (blocking the air suction vortex E), with the latter effect being particularly large.

[0028] 1 to 3, the vortex suppression structure 30 mainly has a horizontal member 31 and a vertical member 32. Both the horizontal member 31 and the vertical member 32 are gutter-shaped and disposed outside the casing 11. The horizontal member 31 extends along the circumferential direction of the casing 11 at a portion that defines the suction port 11a in the casing 11, specifically, on the outer circumferential side of the lower end of the trumpet tube 12. The horizontal member 31 is fixed to the casing 11 in an orientation that is open toward the upper side and the center. The vertical member 32 extends upward from the horizontal member 31.

[0029] At least the upper end of the vertical member 32 is open to the upstream side in the water flow direction. Here, "open to the upstream side" means at least the design intent of the vertical member 32 or the vortex suppression structure 30. At the manufacturing stage of the pump 10, it is difficult to accurately predict the flow field in the water tank 1 into which the pump 10 is newly installed. Therefore, the vertical member 32 may not be opened to the upstream side contrary to expectations immediately after the start of practical use. However, the pump 10 according to this embodiment is configured such that even if the vertical member 32 is not opened to the upstream side immediately after the start of practical use, the attitude of the vertical member 32 relative to the water tank 1 can be adjusted so that the vertical member 32 is opened to the upstream side in a subsequent maintenance work. In the following description, unless otherwise specified, the vertical member 32 is attached to the casing 11 in an attitude opened to the upstream side of the water flow F according to the design intent as shown in FIG. 2.

[0030] The cross member 31 has a quarter-circular arc shape in a plan view, and extends along the circumferential direction of the casing 11 on the outer periphery of the trumpet tube 12 that forms the suction port 11a. The cross member 31 has a quarter-circular arc shape in a cross section perpendicular to the extension direction.

[0031] As an example of a method for manufacturing such a cross member 31, a metal tube material forming a ring-shaped body (torus) is prepared. This tube material is divided into four parts along the circumferential direction of the large circle (center curve C31) of the torus. The tube material obtained in this way has a 1 / 4 arc shape centered on the center of the large circle of the torus in a plan view. In a cross section perpendicular to the extension direction of the tube material, the tube material has a circular shape corresponding to the small circle of the torus. The tube material is divided so that the circular cross section corresponding to the small circle forms a 1 / 4 arc cross section. The tube material is divided in the radial direction by a vertical cut surface along the center curve C31 of the torus, and is divided in the vertical direction by a horizontal cut surface along the center curve of the torus. The center curve C31 extends in both cut surfaces. The broken tube material on the lower and outer periphery side formed by this division serves as the cross member 31. Instead of dividing the torus-forming tube into four parts, a metal circular tube extending in a straight line may be bent to form a quarter arc.

[0032] The upper and outer peripheral edge of the cross member 31 (hereinafter simply referred to as the upper edge 31a) extends in an arc shape centered on the central axis of the casing 11 in plan view and faces generally upward. The radius of the upper edge 31a corresponds to the sum of the majority radius and the minor radius of the torus. The lower and inner peripheral edge of the cross member 31 (hereinafter simply referred to as the inner peripheral edge 31b) also extends in an arc shape centered on the central axis of the casing 11 in plan view. The radius of the inner peripheral edge 31b corresponds to the majority radius of the torus.

[0033] In this embodiment, two horizontal members 31 are attached to the casing 11 so as to be aligned in the circumferential direction. Since each horizontal member 31 has a quarter-circular arc shape in a plan view, the two horizontal members 31 are connected to each other so as to describe a semicircular arc in a plan view. The vertical members 32 correspond one-to-one to the horizontal members 31. That is, the pump 10 is provided with two horizontal members 31 and two vertical members 32.

[0034] The vertical member 32 is expanded toward the bottom. In a horizontal cross section taken at any position in the vertical direction, the vertical member 32 is arc-shaped, and the radius of the vertical member 32 is larger toward the bottom. FIG. 4 shows the relationship between the vertical distance from the top end of the vertical member 32 (how far it is downward from the top end) and the radius of the arc that appears in the horizontal cross section. The radius of the vertical member 32 is a minimum value r at the top end and a maximum value R at the bottom end 32a that is a distance h away from the top end. As shown by the solid line, the radius may change linearly from the minimum value r to the maximum value R according to the distance. As shown by the dashed and dotted lines, the radius may change nonlinearly. In that case, the radius may change along an upwardly convex curve (i.e., the rate of change of the radius is gentler toward the top end) or along a downwardly convex curve (i.e., the rate of change of the radius is steeper toward the top end).

[0035] As an example of a method for manufacturing such a vertical member 32, a straight metal circular tube is prepared. The circular tube is divided radially by a vertical cutting plane passing through its center line to obtain a semicircular tube. The semicircular tube is forged to expand so that the diameter becomes larger toward the bottom. In this way, the vertical member 32 is obtained. Since the vertical member 32 is manufactured in this manner, in the horizontal cross section of the vertical member 32, the radius of the arc is larger toward the bottom, while the length of the arc is approximately constant in the up-down direction (although the arc length may be slightly longer toward the bottom due to ductility).

[0036] The manufacturing method of the horizontal member 31 is not limited to cutting or bending a metal tube, and the horizontal member 31 may be manufactured by casting a metal material or injection molding of a synthetic resin. The manufacturing method of the vertical member 32 is not limited to cutting and forging a metal tube, and the vertical member 32 may be manufactured by casting a metal material or injection molding of a synthetic resin. When both the horizontal member 31 and the vertical member 32 are made of metal, the horizontal member 31 and the vertical member 32 are manufactured from the same type of metal for convenience of welding.

[0037] The lower end of the vertical member 32 is arc-shaped. The lower end of the vertical member 32 has the same diameter as the upper edge 31a of the horizontal member 31. The vertical member 32 is butt-welded to the horizontal member 31. In this butt welding, the lower end surface of the vertical member 32 is in surface contact with the upper end surface of the horizontal member 31. When the horizontal member 31 and the vertical member 32 are made of the same metal, such metallurgical joining can be easily applied. When the horizontal member 31 and the vertical member 32 are made of synthetic resin, other appropriate joining means such as heat fusion are applied.

[0038] One horizontal member 31 and one vertical member 32 constitute one module 30A of the vortex suppression structure 30. In this embodiment, two modules 30A are attached to the pump 10. The horizontal member 31 is provided on the outer periphery side of the casing 11 to form a semicircle, and the two vertical members 32 extend in the up-down direction on the outer periphery side of the casing 11. The interval between the two vertical members 32 is within a range of 45 degrees to 100 degrees around the central axis of the casing 11. In this embodiment, the interval is 90 degrees, just as an example.

[0039] The horizontal member 31 is removably attached to the casing 11 (particularly, the trumpet tube 12) via a lower fixing member 33. The vertical member 32 is removably attached to the casing 11 (particularly, the pump casing 13) via an upper fixing member 34. The horizontal member 31 is attached to the casing 11 at two points, one end and the other end in the circumferential direction, via two lower fixing members 33. Since the attachment method is the same for the two points, only one of the attachment structures will be described, and a duplicated description of the other will be omitted. In this embodiment, the vertical member 32 is attached to the casing 11 at one point by one upper fixing member 34. However, this is just one example, and multiple upper fixing members 34 may be arranged at intervals in the circumferential direction or may be arranged at intervals in the vertical direction.

[0040] 5A to 5C, the lower fixing member 33 includes a beam portion 33a extending radially between the casing 11 and the horizontal member 31, an inner peripheral side mounting portion 33b provided at an inner peripheral side end portion of the beam portion 33a (i.e., an end portion on the side that interfaces with the casing 11), and an outer peripheral side mounting portion 33c provided at an outer peripheral side end portion of the beam portion 33a (i.e., an end portion on the side that interfaces with the horizontal member 31). The lower fixing member 33 is manufactured from a metal material such as steel or an aluminum alloy. The inner peripheral side mounting portion 33b and the outer peripheral side mounting portion 33c are integrated with the beam portion 33a by welding or the like.

[0041] The beam portion 33a has a solid or hollow rectangular shape in a cross section perpendicular to the extending direction of the beam portion 33a (the radial direction of the casing 11). This rectangle is elongated, with its long sides extending along the vertical direction and its short sides extending along the circumferential direction of the casing 11.

[0042] The inner peripheral side mounting portion 33b is plate-shaped. The inner peripheral side mounting portion 33b is provided at the end of the beam portion 33a so that the plate thickness direction of the inner peripheral side mounting portion 33b faces the extending direction of the beam portion 33a. The inner peripheral side mounting portion 33b is removably connected to the lower fixed seat 17 provided on the outer surface side of the casing 11 by a bolt 35 in a state of surface contact with the lower fixed seat 17. The lower fixed seat 17 is formed by partially thickening the casing 11, and protrudes slightly in the radial direction from the outer surface of the casing 11. In this embodiment, the lower fixed seat 17 is provided at the lower end of the casing 11, more specifically, on the outer surface side of the lowest trumpet tube 12 among the casing members constituting the casing 11.

[0043] The outer peripheral side mounting portion 33c is also plate-shaped like the inner peripheral side mounting portion 33b, and is provided at the end of the beam portion 33a with its plate thickness direction facing the extension direction of the beam portion 33a. The outer peripheral side mounting portion 33c is fixed to the horizontal member 31 in a state of surface contact with the inner peripheral surface of the horizontal member 31.

[0044] 6 and 6B, the upper fixing member 34 has a beam portion 34a extending radially or in a direction inclined thereto between the casing 11 and the vertical member 32. An inner peripheral side end portion 34b joined to the outer surface of the casing 11 is provided at an inner peripheral side end portion of the beam portion 34a (i.e., an end portion on the side that interfaces with the casing 11). An outer peripheral side end portion 34c joined to the inner surface of the vertical member 32 is provided at an outer peripheral side end portion of the beam portion 34a (i.e., an end portion on the side that interfaces with the vertical member 32).

[0045] The beam portion 34a has a solid or hollow rectangular shape in a cross section perpendicular to the extending direction of the beam portion 34a (the direction inclined toward the radial direction of the casing 11). This rectangle is elongated, with its long sides extending along the vertical direction and its short sides extending along the circumferential direction of the casing 11.

[0046] The inner peripheral side mounting portion 34b is plate-shaped. The inner peripheral side mounting portion 34b is provided at the end of the beam portion 34a so that the plate thickness direction of the inner peripheral side mounting portion 34b faces the extending direction of the beam portion 34a. The inner peripheral side mounting portion 34b is removably connected to the upper fixed seat 18 provided on the outer surface side of the casing 11 by a bolt 36 in a state of surface contact with the upper fixed seat 18. The upper fixed seat 18 is also formed by partially thickening the casing 11, similar to the lower fixed seat 17, and protrudes slightly in the radial direction from the outer surface of the casing 11. In this embodiment, the upper fixed seat 18 is provided above the lower fixed seat 17 and is arranged apart from the lower fixed seat 17 in the circumferential direction. More specifically, the upper fixed seat 18 is provided on the outer surface side of the pump casing 13 adjacent to the upper part of the lowest trumpet tube among the casing members constituting the casing 11.

[0047] The outer peripheral side mounting portion 34c is plate-shaped and is provided at the end of the beam portion 34a so that the thickness direction of the outer peripheral side mounting portion 34c faces the extension direction of the beam portion 34a. The outer peripheral side mounting portion 34c is fixed to the vertical member 32 in a state of surface contact with the inner surface 32b of the vertical member 32.

[0048] The outer circumferential mounting portion 33c of the lower fixing member 33 may be integrated with the horizontal member 31 by welding or the like. That is, the outer circumferential mounting portion 33c may be integrated with the module 30A of the vortex suppression structure 30 configured with the horizontal member 31 and the vertical members 32. The outer circumferential mounting portion 33c may be removably fixed to the horizontal member 31 with a bolt, similar to the inner circumferential mounting portion 33b. The same applies to the outer circumferential mounting portion 34c of the upper fixing member 34.

[0049] In a pump 10 equipped with such a vortex suppression structure 30, when the water level becomes low, for example when the water level reaches the lowest water level LWL, an air-sucking vortex E can develop downstream of the pump 10. The air-sucking vortex E is generated between the casing 11 and the end face 1c of the water tank 1. The vortex suppression structure 30 faces closely the outer periphery of the casing 11, and is closer to the central axis A of the pump 10 in the radial direction than the generation position of the air-sucking vortex E. In other words, the generation position of the air-sucking vortex E is on the outer surface of the vertical member 32 or further outwardly than this.

[0050] A water flow F is generated on the water surface. The water flow F flows around the outer periphery of the casing 11 and attempts to flow toward the end face 1c. The upper end of the vertical member 32 is open toward the upstream side of the water flow F, and the water flow F is received by the inner surface 32b of the vertical member 32 (see arrow F1a in FIG. 3).

[0051] Due to the influence of the suction of the pump 10, the water flow F1 received at the upper end of the vertical member 32 flows vertically downward along the inner surface of the vertical member 32 (see arrow F1b in FIG. 3). The vertical member 32 is wider toward the bottom. Therefore, the water flow F1 is guided by the inner surface 32b of the vertical member 32 and flows downward in the circumferential direction around the central axis A of the pump 10.

[0052] 6B, a part of the water flow F1 passes from top to bottom around the beam portion 34a of the upper fixing member 34. The long side of the beam portion 34a extends vertically, but is inclined at an angle β with respect to the vertical line around an imaginary axis extending in the extension direction of the beam portion 34a (roughly the radial direction of the pump 10). Due to this inclination of the beam portion 34a, the water flow F1 is guided by the surface of the beam portion 34a and directed in the circumferential direction as it flows downward around the beam portion 34a. In this way, the water flow F1 is guided not only by the vertical member 32 but also by the upper fixing member 34, and flows in the circumferential direction.

[0053] When the water flow F1 reaches the vicinity of the lower end 32a of the vertical member 32, it is received by the inner surface of the horizontal member 31, which is open upward. The lower end 32a of the vertical member 32 is integrated with the upper edge 31a of the horizontal member 31, and the inner surface 32b of the vertical member 32 smoothly continues with the inner surface of the horizontal member 31 in the up-down direction. Therefore, the water flow F1 flows smoothly toward the inner surface side of the vertical member 32.

[0054] The water flow F2 received by the inner surface of the cross member 31 is guided by the inner surface of the cross member 31 and flows downward, toward the center in the radial direction of the pump 10 (see arrow F2a in FIG. 3).

[0055] 5C, part of the water flow F2 passes from top to bottom around the beam portion 33a of the lower fixed member 33. The long side of the beam portion 33a extends vertically, but is inclined at an angle α with respect to the vertical line about a virtual axis extending in the extension direction of the beam portion 33a (roughly the radial direction of the pump 10). Due to this inclination of the beam portion 33a, the water flow F2 is guided by the surface of the beam portion 33a and directed in the circumferential direction as it flows downward around the beam portion 33a. In this way, the water flow F2 is guided not only by the horizontal member 31 but also by the lower fixed member 33, and flows in the circumferential direction.

[0056] The horizontal member 31 is disposed on the outer periphery side of the suction port 11a, and a clearance 30a is formed between the inner peripheral edge 31b of the horizontal member 31 and the lower end edge of the trumpet tube 12 (the peripheral portion of the suction port 11a). The water flow F2 passes through this clearance 30a (see arrow F2b in FIG. 3) and is sucked into the casing 11 through the suction port 11a. The presence of this clearance 30a allows a downward water flow F1 to be formed near the upper end of the inner surface 32b of the vertical member 32.

[0057] The air-sucking vortex E is generated on the outer circumferential side of the vertical member 32 and moves toward the suction port 11a, but is prevented from reaching the suction port 11a by the water flow F2. In this manner, according to the present embodiment, the air-sucking vortex E can be prevented from flowing into the casing 11.

[0058] In particular, the water currents F1 and F2 flow in the circumferential direction. That is, the area in which the air-sucking vortex E can be blocked expands in the circumferential direction. For this reason, the vortex suppression structure 30 can block the air-sucking vortex E even if it is not strictly positioned in the circumferential direction relative to the casing 11 or the position in the circumferential direction relative to the generation position of the air-sucking vortex E. This is beneficial in that it makes it easier to suppress the air-sucking vortex E.

[0059] The upper end of the vertical member 32 is located above the lowest water level LWL at which water can be drained. Even if the water level in the aquarium 1 is at the lowest water level LWL, the water flow F on the water surface can be received by the upper end of the vertical member 32. Therefore, according to the above-mentioned principle, the intake of the air-sucking vortex E can be suppressed. In addition, the lower end of the horizontal member 31 is located below the suction port 11a. The water flow F2 flowing from the horizontal member 31 toward the center is more likely to flow upward through the suction port 11a. Therefore, it is easy to block the air-sucking vortex E by using the water flow F.

[0060] As described above, the shape of the water tank 1 varies depending on the topographical conditions of the plant. Therefore, when the pump 10 is newly installed, it is difficult to accurately predict the flow field before the pump 10 is put into service, and it is difficult to accurately identify the location where the air-suction vortex E occurs. Therefore, as shown in FIG. 7, the vortex suppression structure 30 may be provided around the entire circumference of the pump 10 at the start of use. In this case, as an example, four modules 30A, 30B, 30C, and 30D having a quarter-circular arc shape in a plan view are removably coupled to the casing 11. While the pump 10 is in operation, the modules that contribute more to blocking the air-suction vortex E are identified, and during regular maintenance, the modules that contribute less to blocking the air-suction vortex E are removed. In the illustrated example, since the water flow F has a component directed toward the side surface 1b, the modules 30B and 30D facing the side surface 1b remain, and the modules 30A and 30C opposite the side surface 1b can be removed. In this way, by removably fixing the vortex suppression structure 30 to the casing 11, even if the flow field is different from that of a standard water tank, it is possible to create a situation in which the air-sucking vortex E can be suppressed.

[0061] Although the embodiment has been described above, the above configuration can be modified as appropriate within the scope of the present invention.

[0062] For example, the horizontal member 31 does not have to be a quarter arc shape. For example, as shown in FIG. 8, the horizontal member 31 may be formed in an L-shape. In this case, the horizontal member 31 includes a peripheral wall 31c extending vertically and circumferentially, and a bottom wall 31d extending horizontally and radially from the lower end of the peripheral wall 31c toward the center. The upper end of the peripheral wall 31c serves as the upper edge 31a in the above embodiment and is joined to the lower end 32a of the vertical member 32. The inner peripheral edge of the bottom wall 31d serves as the inner peripheral edge 31b in the above embodiment and defines a clearance 30a between the bottom wall 31d and the peripheral edge of the suction port 11a. The vertical member 32 may also have any shape as long as it is open to the upstream side so as to receive the water flow F. The vertical member 32 is not limited to an arc shape and may be formed in other shapes, such as an L-shape. [Explanation of symbols]

[0063] 1. Aquarium 1a Bottom 1b side 1c end face 2 Beds 2a aperture 10. Pump 11 Casing 11a Intake port 11b Discharge port 12 Trumpet 13 Pump casing 14. Lifting pipe 15 Hanging pipe 16 Discharge pipe 17 Lower fixed seat 18 Upper fixed seat 21 Rotation axis 22 Impeller 23 Bearings 30 Vortex suppression structure 30A, 30B, 30C, 30D Module 31 Horizontal member 31a Upper edge 31b Inner edge 31c Peripheral wall 31d bottom wall 32 Vertical members 32a bottom end 32b Inside 33 Lower fixing member 33a Beam section 33b Inner circumference mounting part 33c Outer periphery mounting part 34 Upper fixing member 34a Beam section 34b Inner circumference mounting part 34c Outer periphery mounting part 35,36 Volts A center axis E Air-suction vortex F,F1,F2 Water flow LWL Lowest water level

Claims

1. a casing extending upward from near the bottom of the water tank and having a suction port at its lower end for sucking in water from within the water tank; a gutter-shaped horizontal member extending along a circumferential direction of the casing on an outer circumferential side of a portion of the casing that defines the suction port and opening upward and toward a center of the casing; A gutter-shaped vertical member that extends upward from the horizontal member and is attached to the casing so as to be open at least at an upper end to an upstream side in the water flow direction; A pump comprising:

2. The vertical member is expanded toward the bottom.

2. The pump of claim 1.

3. The lower end of the vertical member is arcuate with the same diameter as the upper end edge of the horizontal member and is fixed to the upper end edge of the horizontal member.

3. A pump according to claim 1 or 2.

4. The lower end of the cross member is located below the suction port.

3. A pump according to claim 1 or 2.

5. The upper end of the vertical member is located above the lowest water level that can be drained.

3. A pump according to claim 1 or 2.

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