Pump liquid suction tank

Abstract

To provide a pump water suction tank that can improve the degree of freedom of a pump to be applied.SOLUTION: A pump liquid suction tank 10 comprises: a bottom surface 20 provided at an interval on a lower side of a suction port 6a; a pair of side surfaces 21 provided at an interval in a width direction with respect to a pump casing 6; an end surface 22 provided at an interval on a downstream side with respect to the pump casing 6; a chamfered surface 24 provided at an interval on an upstream side with respect to the pump casing 6, and gradually decreasing an opening area between itself and the bottom surface 20 as going toward the downstream side; and a beam 26 provided between the pump casing 6 and the end surface 22, and extending the width direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] The pump suction sump disclosed in Patent Document 1 is designed to reduce vibrations and the like by suppressing the generation of vortexes inside. This pump suction sump is of a closed type that includes a bottom wall, side upright walls, a rear upright wall, and a top wall, with a pump casing integrally formed so as to be continuous with the top wall. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2003-206885 Summary of the Invention [Problem to be solved by the invention]

[0004] The pump suction tank described in Patent Document 1 has a pump casing as an integral part, so the pump to be applied cannot be changed. Therefore, the pump suction tank of Patent Document 1 has room for improvement in terms of increasing the flexibility of the pump to be applied.

[0005] An object of the present invention is to provide a pump suction tank that can improve the degree of freedom in the type of pump that can be used. [Means for solving the problem]

[0006] The vortexes that may occur in the pump suction tank include air suction vortices and submerged vortices. Air suction vortices are vortices that extend from the liquid surface to the pump suction port and contain air on the liquid surface continuously or intermittently, and occur around the pump casing (lifting pipe) in the pump suction tank. Submerged vortices are vortices that extend from the wall that defines the pump suction tank to the pump suction port and contain gas (bubbles) caused by cavitation continuously or intermittently, and occur around the pump casing in the pump suction tank. The inventors of the present application have found that the occurrence of air suction vortices and submerged vortices is due to a sudden increase in the flow rate near the pump casing due to the discharge of liquid. The present invention was made based on such findings.

[0007] One aspect of the present invention provides a pump suction tank comprising: a bottom surface provided at a distance below a suction port and extending from an upstream side to a downstream side in a direction of liquid inflow relative to a pump casing; a pair of side surfaces provided at a distance in a width direction, which is a direction intersecting the inflow direction, relative to the pump casing, and protruding upward from both sides of the bottom surface in the width direction; end surfaces provided at a distance on the downstream side relative to the pump casing and closing the downstream sides of the bottom surface and the pair of side surfaces; chamfered surfaces provided at a distance on the upstream side relative to the pump casing, extending in the width direction adjacent to a lower side of a minimum liquid level that can be discharged, and gradually reducing an opening area between the bottom surface and the pair of side surfaces toward the downstream side; and a beam provided between the pump casing and the end surface, extending in the width direction adjacent to a lower side of the minimum liquid level.

[0008] The pump suction tank has a bottom surface, a pair of side surfaces, end surfaces, a chamfered surface, and a beam, all of which are provided at intervals from the pump casing. In other words, since the pump suction tank and the pump casing are provided separately, there is no restriction on the pumps that can be applied to the pump suction tank. This improves the degree of freedom in the pumps that can be applied.

[0009] The upstream side of the pump casing is provided with a chamfered surface adjacent to the lower side of the minimum liquid level, the opening area between the chamfered surface and the bottom surface gradually decreasing toward the downstream side. This causes the flow rate of the liquid in the pump suction tank to gradually increase from the upstream side to the downstream side. This makes it possible to suppress a sudden increase in the flow rate of the liquid near the pump casing and the occurrence of an air suction vortex due to flow separation.

[0010] A beam is provided between the pump casing and the end face, extending in the width direction adjacent to the lower side of the minimum liquid level. This beam can destroy air suction vortices and submerged vortices that may occur in the area downstream of the closed pump casing, thereby suppressing the occurrence of vortexes in the pump suction tank. Effect of the Invention

[0011] The present invention can improve the degree of freedom in the pump to be applied. [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective view of a pump water suction tank according to a first embodiment of the present invention. FIG. [Diagram 2] Cross-sectional view of line II-II in Figure 1. [Diagram 3] FIG. 2 is a cross-sectional view of the pump suction sump taken along line III-III in FIG. [Figure 4] FIG. 4 is a perspective view of FIG. [Diagram 5] Cross-sectional view of line VV in Figure 2. [Figure 6] 5 is a cross-sectional view similar to FIG. 2 of a pump suction tank according to a second embodiment. FIG. [Figure 7] 10 is a cross-sectional view similar to FIG. 2 of a pump suction tank according to a third embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0014] In the attached drawings, the X direction indicates the water inflow direction, the direction indicated by the arrow is the downstream side, and the direction opposite to the arrow is the upstream side, the Y direction indicates the width direction of the pump suction tank 10 which is perpendicular (intersecting) to the inflow direction, and the Z direction indicates the depth direction of the pump suction tank 10.

[0015] (First embodiment) 1 and 2, a pump facility 1 using a pump suction sump (hereinafter referred to as the "suction sump") 10 according to a first embodiment of the present invention includes the suction sump (high flow rate suction sump) 10 and a vertical pump 5.

[0016] The vertical pump 5 includes a pump casing (lifting pipe) 6, a rotating shaft 7, an impeller 8, and a drive source (e.g., an electric motor, etc.) (not shown). The impeller 8 is rotated integrally by the rotation of the rotating shaft 7 by the drive source, and water (liquid), such as rainwater that has flowed into a suction tank (liquid suction tank) 10 from a sewer pipe (not shown), is sucked in through a suction port 6a at the lower end of the pump casing 6 and discharged downstream. However, the liquid discharged by the vertical pump 5 may be something other than water.

[0017] 2 and 3, the suction sump 10 includes a bottom wall 15, a pair of side walls 16, an end wall 17, and a top wall 18, and the upstream end of the suction sump 10 is connected to a sewer pipe. A through-hole 18d is provided in the top wall 18, and the pump casing 6 of the vertical pump 5 is disposed to pass through this through-hole 18d. In other words, the suction sump 10 is a semi-closed type provided separately from the pump casing 6. Therefore, pumps other than the vertical pump 5, such as a horizontal pump, can also be applied to the suction sump 10 of this embodiment as long as they can pass through the through-hole 18d.

[0018] In the conventional suction sump 10, an air-suction vortex and a submerged vortex (a submerged vortex) may occur. The air-suction vortex is a vortex that extends from the liquid surface around the pump casing 6 to the suction port 6a and contains air above the liquid surface continuously or intermittently. The submerged vortex is a vortex that extends from the bottom wall 15, a pair of side walls 16, and an end wall 17 around the pump casing 6 to the suction port 6a of the vertical pump 5 and contains gas (bubbles) caused by cavitation continuously or intermittently.

[0019] Air suction vortexes and submerged vortices are likely to occur when the water level in the suction sump 10 drops to near the minimum water level LWL shown in Fig. 2 due to drainage, because the water flow speed around the pump casing 6 increases suddenly. The minimum water level LWL corresponds to the position of the upper end of the impeller 8, and is the lowest water level at which water can be efficiently drained without containing harmful air or cavitation. As the water level in the suction sump 10 falls below the minimum water level LWL due to drainage, the drainage efficiency decreases, and the vertical pump 5 operates in a gas-liquid mixed state that contains air.

[0020] In order to suppress the generation of harmful vortexes when the water level is near the lowest water level LWL, the suction sump 10 of this embodiment is defined by a bottom surface 20, a pair of side surfaces 21, an end surface 22, a top surface 23, corner inclined surfaces 27, lateral lower inclined surfaces 28, and a rear lower inclined surface 29. The suction sump 10 also has chamfered surfaces 24, protruding portions 25, beams 26, and pillar portions 30.

[0021] The configuration of the water suction tank 10 of this embodiment will be specifically described below.

[0022] 2 and 3, the suction tank 10 is formed by placing the metal tank mold 12 shown in Fig. 1 in a hole provided in the industrial yard and pouring concrete into it. However, the suction tank 10 may also be formed by forming the tank mold 12 from a wooden mold and removing the tank mold 12 after the poured concrete has hardened, and the method of pouring the concrete can be changed as required.

[0023] 1 and 2, the bottom wall 15 extends from the upstream side to the downstream side in the water inflow direction with respect to the pump casing 6. With reference to FIGS. 3 and 4, the bottom wall 15 is provided with a protruding portion 25 protruding upward at the end on the downstream side and in the center of the width direction so as to be located directly below the pump casing 6. The bottom surface 20 of the bottom wall 15, which is the surface on the inside of the tank other than the protruding portion 25, has a hexagonal shape with an isosceles trapezoidal end when viewed from above, is provided below the suction port 6a of the vertical pump 5 with a gap therebetween, and is composed of a flat surface extending in the XY plane (horizontal direction). However, the bottom surface 20 may be inclined downward from the upstream side to the downstream side. The protruding portion 25 will be described in detail later.

[0024] 1 to 3, the pair of side walls 16 protrude upward from both sides of the bottom wall 15 in the width direction and face each other in the width direction. Of the pair of side walls 16, a side surface 21 which is the surface on the inside of the tank is provided with a gap in the width direction relative to the pump casing 6 and is configured by a flat surface extending in a direction perpendicular to the bottom surface 20 (XZ plane). However, the side surface 21 may be inclined outward in the width direction or toward the center in the width direction as it extends upward. The side surface 21 may also be configured by a curved surface.

[0025] Each of the pair of side surfaces 21 has a portion with a different overall height, which is the amount of protrusion from the bottom surface 20. Specifically, the side surface 21 has an upstream water storage section 21a with a high overall height and a downstream drainage section 21b with a low overall height. Between the water storage section 21a and the drainage section 21b, a continuous section 21c is provided whose overall height gradually increases from the downstream side to the upstream side. The overall height of the water storage section 21a is set higher than the lowest water level LWL and based on the volume capable of storing the maximum anticipated inflow amount of water. The overall heights of the drainage section 21b and the continuous section 21c are set lower than the lowest water level LWL. The continuous section 21c is provided to form a chamfered surface 24, which will be described in detail later.

[0026] The height of the drainage section 21b is set based on the flow velocity (approaching flow velocity) of water approaching the pump casing 6 from the upstream side. In a conventional suction tank without a vortex suppression structure, the approaching flow velocity V is limited to 0.3 m / s or less, and when the water level falls below the minimum water level LWL, the approaching flow velocity V suddenly increases to 0.4 m / s, which can cause air-sucking vortices and underwater vortices to occur. In contrast, in this embodiment, by using other configurations including the height of the drainage section 21b to increase the approaching flow velocity V to 0.75 m / s, the flow velocity range in which harmful air-sucking vortices and underwater vortices occur is removed, and their occurrence is suppressed.

[0027] The end wall 17 is provided to close the downstream side of the bottom wall 15 and the pair of side walls 16. A pillar portion 30 is provided at the center of the width of the end wall 17, which protrudes upstream toward the pump casing 6 to form a triangle shape when viewed from above and extends in the vertical direction. An end face 22, which is the surface of the end wall 17 on the inside of the tank other than the pillar portion 30, is provided downstream with a gap from the pump casing 6. The end face 22 is connected to the bottom face 20 via a rear lower inclined face 29, and is connected to a pair of side faces 21 via a pair of corner inclined faces 27. The end face 22 is formed of a flat surface extending in a direction perpendicular to the bottom face 20 and the side face 21. However, the end face 22 may be inclined toward the downstream side or the upstream side from the bottom side to the top side. The end face 22 may also be formed of a curved surface. The pillar portion 30 will be described in detail later.

[0028] The top wall 18 is provided to cover the upper ends of the pair of side walls 16 and the end wall 17. More specifically, the top wall 18 is composed of first to third wall portions 18a to 18c. The first wall portion 18a closes the upper end of the water storage portion 21a of the pair of side walls 16. The second wall portion 18b covers the upper ends of the drainage portion 21b of the pair of side walls 16 and the end surface 22 of the end wall 17. The third wall portion 18c is connected to the downstream end of the first wall portion 18a and the upstream end of the second wall portion 18b, and closes the upper end of the continuous portion 21c of the pair of side walls 16. The thickness of the second wall portion 18b and the third wall portion 18c in the vertical direction is thicker than the thickness of the first wall portion 18a. The upper surfaces of the second wall portion 18b and the third wall portion 18c are located at the same height as the upper surface of the first wall portion 18a and are flush with each other.

[0029] The second wall portion 18b covering the drainage portion 21b is provided with a through-hole 18d for inserting the pump casing 6 therethrough. The diameter of the through-hole 18d is larger than the maximum diameter of the pump casing 6 that may be installed. The upper end position of the through-hole 18d is higher than the water level (highest water level HWL) when the maximum anticipated inflow amount of water is stored.

[0030] The first top surface 23a, which is the tank inner surface of the first wall portion 18a of the top wall 18, is connected to the upper ends of the water storage portions 21a of the pair of side surfaces 21, and is a flat surface extending along the XY plane facing upward relative to the bottom surface 20. The second top surface 23b, which is the tank inner surface of the second wall portion 18b of the top wall 18, is connected to the upper ends of the drainage portions 21b and the end faces 22 of the pair of side surfaces 21, and is a flat surface extending along the XY plane facing upward relative to the bottom surface 20. The chamfered surface 24, which is the tank inner surface of the third wall portion 18c of the top wall 18, is connected to the upper ends of the continuous portions 21c of the pair of side surfaces 21, and is a flat surface inclined downward from the upstream side to the downstream side in the inflow direction.

[0031] The chamfered surface 24 is formed by a part of the top wall 18. This chamfered surface 24 is provided on the upstream side of the pump casing 6 with a gap therebetween so as to be adjacent to the lower side of the lowest water level LWL. The chamfered surface 24 is formed of a flat inclined surface that slopes downward from the upstream side to the downstream side, and extends in the width direction, continuing to each of the side surfaces 21 of the pair of side walls 16. Due to this chamfered surface 24, the opening area between the chamfered surface 24 and the bottom surface 20 gradually decreases toward the downstream side. As a result, the flow speed of water from the upstream side toward the pump casing 6 is configured to gradually increase.

[0032] 2, the lower end of the chamfered surface 24 including the second top surface 23b of the top wall 18 is located below the lowest water level LWL and above the lower end of the impeller 8. This position corresponds to the water level at which the vertical pump 5 can operate in a gas-liquid mixed state that includes air.

[0033] If the suction port 6a of the vertical pump 5 has a diameter Db, the distance from the axis A of the vertical pump 5 to the downstream end of the chamfered surface 24 is set to a distance αDb. The coefficient α is preferably set in the numerical range of 1.00 to 1.10, and is set to 1.06 in this embodiment. This numerical range of the coefficient α was found by the inventors of the present application through extensive experiments from the region where an air-suction vortex may occur upstream of the pump casing 6.

[0034] If the inclination angle θ of the chamfered surface 24 with respect to the inflow direction is too large, the flow velocity changes too abruptly, whereas if the inclination angle θ is too small, the flow velocity changes too gently. If the distance C from the upstream end to the downstream end of the chamfered surface 24 is too short, the flow velocity changes too abruptly, whereas if the distance C is too long, the flow velocity changes too gently. Therefore, the inclination angle θ of the chamfered surface 24 with respect to the inflow direction is preferably set in the angle range of 20 degrees to 40 degrees, and is set to 30 degrees in this embodiment. Moreover, the distance C from the upstream end to the downstream end of the chamfered surface 24 is preferably set in the range of 20% to 40% of the diameter Db of the suction port 6a of the vertical shaft pump 5, and is set to 28% in this embodiment.

[0035] 3 to 5, protrusion 25 protrudes upward from bottom surface 20 of bottom wall 15. Protrusion 25 is provided to gradually increase the flow rate of water toward suction port 6a of vertical pump 5 and to make the water flow sucked from suction port 6a curved flow Fc of less than 90 degrees. Protrusion 25 is generally pyramidal in shape and includes top inclined surface 25a and a pair of side inclined surfaces 25b.

[0036] Top inclined surface 25a is provided upstream of pump casing 6, more specifically, in the region from between the downstream end of chamfered surface 24 and pump casing 6 to end wall 17. Top inclined surface 25a is flat, inclined upward from the upstream side to the downstream side, and positioned with a gap relative to suction port 6a of vertical pump 5. The width in the width direction of top inclined surface 25a is as small as possible while still allowing the formation of a pair of side inclined surfaces 25b.

[0037] The pair of side inclined surfaces 25b are provided so as to be continuous with both sides of the top inclined surface 25a in the width direction. The pair of side inclined surfaces 25b are flat surfaces and inclined outward in the width direction as they go downward. If the maximum width W, which is the dimension between the downstream ends of the pair of side inclined surfaces 25b, is excessively large, the inclination angle of the side inclined surfaces 25b with respect to the bottom surface 20 becomes too gentle, and the flow speed toward the suction port 6a becomes slow. On the other hand, if the maximum width W is excessively small, the inclination angle of the side inclined surfaces 25b with respect to the bottom surface 20 becomes too steep, and the flow speed toward the suction port 6a becomes too fast. Therefore, it is preferable that the maximum width W of the pair of side inclined surfaces 25b is set to a range of 40% to 60% of the diameter Db of the suction port 6a of the vertical pump 5, and is set to 50% in this embodiment.

[0038] 2 to 4, the beam 26 is provided between the pump casing 6 and the end face 22, and extends in the width direction, connected to each of a pair of corner inclined faces 27. The beam 26 is provided at a distance downstream from the pump casing 6 so as to be adjacent to the lower side of the lowest water level LWL. The beam 26 in this embodiment has a rectangular cross section, and protrudes downward from the second top face 23b of the top wall 18.

[0039] 2, if the suction port 6a of the vertical pump 5 has a diameter Db, then the distance from the axis A of the vertical pump 5 to the upstream end of the beam 26 is set to a distance βDb. The coefficient β is preferably set in the numerical range of 0.6 to 0.7, and is set to 0.635 in this embodiment. This coefficient β is a value found by the inventors of the present application through extensive experiments from a region where an air-sucking vortex may occur due to flow separation downstream of the pump casing 6.

[0040] 3 to 5, the corner inclined surface 27 is provided to suppress a swirling flow that may occur at the corners of the pair of side walls 16 and the end wall 17. Each of the pair of corner inclined surfaces 27 is pentagonal in shape and inclined toward the center in the width direction from the upstream side to the downstream side. The upstream end of the corner inclined surface 27 is located at the downstream end of the suction port 6a of the vertical shaft pump 5 in the water flow direction, and is connected to the downstream end of the side surface 21. The downstream end of the corner inclined surface 27 is located outside the outer end of the suction port 6a in the width direction, and is connected to the outer end of the end surface 22 in the width direction. The lower end of the corner inclined surface 27 is located below the suction port 6a of the vertical shaft pump 5, and is connected to the side lower inclined surface 28 and the rear lower inclined surface 29, respectively. The inclination angle of the corner inclined surface 27 with respect to each of the side surface 21 and the end surface 22 is 45 degrees. However, the inclination angle of the corner inclined surface 27 can be changed as necessary within a range in which the generation of underwater vortexes can be suppressed.

[0041] The side lower inclined surface 28 is provided to suppress a swirling flow that may occur at the corners between the bottom wall 15 and the pair of side walls 16. Each of the pair of side lower inclined surfaces 28 has a flat kite shape. A lower end 28a of the side lower inclined surface 28 is connected to the bottom surface 20, an upper end 28b of the side lower inclined surface 28 is connected to the side surface 21, and downstream ends 28c, 28d of the side lower inclined surface 28 are connected to the corner inclined surface 27 and the rear lower inclined surface 29, respectively. More specifically, the upstream end of the lower end 28a of the side lower inclined surface 28 is located at the intersection of the bottom surface 20 and the side surface 21 upstream of the pump casing 6, and inclines toward the center in the width direction as it approaches the downstream side. The lateral lower inclined surface 28 thus configured is inclined inward in the width direction from the upstream side to the downstream side when viewed from above, and is connected to the corner inclined surface 27 and the rear lower inclined surface 29 below the suction port 6a. When viewed from the inflow direction, the lateral lower inclined surface 28 is inclined outward in the width direction from the bottom wall 15 toward the upper side, and is connected to the side surface 21 below the suction port 6a of the vertical pump 5. When viewed from the inflow direction, the inclination angle of the lateral lower inclined surface 28 with respect to the bottom surface 20 is approximately 30 degrees. However, the inclination angle of the lateral lower inclined surface 28 can be changed as necessary as long as it is within a range that can suppress the generation of underwater vortexes. The lateral lower inclined surface 28 may be formed of a curved surface.

[0042] The rear lower inclined surfaces 29 are provided on both sides of the column portion 30 to suppress swirling flows that may occur at the corners of the bottom wall 15 and the end wall 17. Each of the pair of rear lower inclined surfaces 29 has a flat pentagonal shape, and is inclined downstream as it moves upward from the bottom wall 15. The lower end of the rear lower inclined surface 29 is connected to the downstream end of the bottom surface 20, the upper end of the rear lower inclined surface 29 is connected to the lower end of the end surface 22, the outer ends of the rear lower inclined surface 29 in the width direction are connected to the corner inclined surface 27 and the side lower inclined surface 28, and the end of the rear lower inclined surface 29 in the width direction center side is connected to the continuous surface 31 described in detail later. The inclination angle of the rear lower inclined surface 29 with respect to the bottom surface 20 is approximately 40 degrees. However, the inclination angle of the rear lower inclined surface 29 can be changed as necessary as long as it is within a range that can suppress the generation of underwater vortexes. The rear lower inclined surface 29 may also be formed of a curved surface.

[0043] The pillar portion 30 is provided to suppress a swirling flow that may occur at the end wall 17. The pillar portion 30 protrudes from the center of the width direction of the end face 22 to the upstream side so as to form a triangular shape when viewed from above, and extends in the vertical direction. The top of the pillar portion 30 is located downstream of the beam 26. The width of the pillar portion 30 in the width direction is the same as the maximum width W of the protruding portion 25. The pillar portion 30 has a pair of rearward inclined surfaces 30a that incline toward the center of the width direction as they approach the upstream side, and whose tips are connected to each other. Each of the pair of rearward inclined surfaces 30a has a flat rectangular shape and extends in the vertical direction. The outer end of the rearward inclined surface 30a in the width direction is connected to the end face 22, the upper end of the rearward inclined surface 30a is connected to the second top face 23b, and the lower end of the rearward inclined surface 30a is connected to the continuous surface 31. The inclination angle of the rearward inclined surface 30a with respect to the end face 22 is approximately 45 degrees. However, the inclination angle of the rear inclined surface 30a can be changed as necessary within a range in which the generation of underwater vortexes can be suppressed.

[0044] The continuous surfaces 31 are provided to suppress swirling flows that may occur at the corners of the protruding portion 25 and the column portion 30. Each of the pair of continuous surfaces 31 has a generally flat triangular shape. The upper end of the continuous surface 31 is continuous with the rear inclined surface 30a, the outer end of the continuous surface 31 in the width direction is continuous with the rear lower inclined surface 29, and the upstream end of the continuous surface 31 is continuous with the side inclined surface 25b.

[0045] In the suction sump 10 thus configured, the flow rate of water near the water surface increases as the water approaches the lowest water level LWL due to drainage by the vertical pump 5. In the region where the chamfered surface 24 is provided in the inflow direction, the opening area between the bottom surface 20 and the water gradually decreases toward the downstream side, so the flow rate of water toward the pump casing 6 gradually increases. Next, when the region where the protruding portion 25 is provided in the inflow direction is reached, the flow rate of water toward the suction port 6a of the vertical pump 5 further increases gradually because the protruding portion 25 is inclined upward toward the downstream side. As a result, while the approach flow rate V of water to the pump casing 6 is 0.40 m / s in a conventional suction sump without the chamfered surface 24 and the protruding portion 25, the approach flow rate V of water can be gradually increased to 0.75 m / s in the suction sump 10 of this embodiment. In addition, because the protruding portion 25 is inclined upward toward the downstream side, the water flowing toward the suction port 6a of the vertical pump 5 becomes a curved flow Fc of less than 90 degrees. As a result, the average flow velocity at the suction port 6a can be increased from 1.7 m / s to approximately 3.4 m / s. As a result, the occurrence of air suction vortexes and submerged vortexes that are harmful to the vertical pump 5 can be effectively suppressed.

[0046] The formation of the top inclined surface 25a, the side inclined surface 25b, the corner inclined surface 27, the side lower inclined surface 28, the rear lower inclined surface 29, the rear inclined surface 30a, and the continuous surface 31 makes it possible to suppress swirling flows that may occur on these surfaces. As a result, the generation of underwater vortexes that are harmful to the vertical pump 5 can be effectively suppressed.

[0047] In this way, the occurrence of air suction vortexes and underwater vortexes can be suppressed, so vibration and noise of the pump equipment 1 can be suppressed, damage to the pump equipment 1 can be prevented, and pump performance can be guaranteed.

[0048] The water suction tank 10 thus constructed has the following features.

[0049] The suction tank 10 has a bottom surface 20, a pair of side surfaces 21, an end surface 22, a chamfered surface 24, and a beam 26, all of which are provided at intervals with respect to the pump casing 6. In other words, since the suction tank 10 and the pump casing 6 are provided separately, there is no restriction on the pump that can be applied to the suction tank 10. This improves the degree of freedom in the pump that can be applied.

[0050] More specifically, a through-hole 18d is formed in the top wall 18, which includes a second top surface 23b that is continuous with the upper ends of the pair of side surfaces 21 and the end surface 22, for passing the pump casing 6 therethrough. As a result, any pump casing 6 that can be passed through the through-hole 18d can be applied to the water suction tank 10. This improves the degree of freedom in the type of pump that can be applied.

[0051] A chamfered surface 24 is provided on the upstream side of the pump casing 6, adjacent to the lower side of the minimum liquid level LWL, so that the opening area between the chamfered surface 24 and the bottom surface 20 gradually decreases toward the downstream side. As a result, in the suction tank 10, the flow rate of the liquid gradually increases from the upstream side to the downstream side. This makes it possible to suppress the generation of an air-sucking vortex caused by a sudden increase in the flow rate of the liquid near the pump casing 6. In addition, since the chamfered surface 24 is formed by a part of the top wall 18, a dedicated part for forming the chamfered surface 24 is not required, and the structure of the suction tank 10 can be simplified.

[0052] A beam 26 extending in the width direction adjacent to the lower side of the minimum liquid level LWL is provided between the pump casing 6 and the end surface 22. This beam 26 can destroy air suction vortexes and submerged vortexes that may occur in the area downstream of the closed pump casing 6. Therefore, the occurrence of vortexes in the suction sump 10 can be suppressed.

[0053] The bottom surface 20 is formed with a protrusion 25 that is inclined upward from the upstream side to the downstream side of the pump casing 6. This allows the flow rate of the liquid to gradually increase from the upstream side to the downstream side not only by the chamfered surface 24 but also by the protrusion 25. In addition, the protrusion 25 gradually reduces the distance between the bottom surface 20 and the suction port 6a of the vertical pump 5, so that the flow of the liquid sucked into the pump casing 6 becomes a curved flow Fc of less than 90 degrees. These actions effectively suppress the generation of an air-suction vortex in the suction tank 10.

[0054] A pair of side inclined surfaces 25b are formed on both sides in the width direction of the protruding portion 25, inclined outward in the width direction as it approaches the lower side. This allows not only the flow rate of the liquid flowing toward the pump casing 6 along the inflow direction but also the flow rate of the liquid flowing toward the pump casing 6 from the outside in the width direction to gradually increase, thereby suppressing the generation of air-suction vortexes in the suction tank 10. In addition, since the swirling flow that can occur on the bottom surface 20 directly below the pump casing 6 can be suppressed, the generation of underwater vortexes extending from the bottom surface 20 to the suction port 6a of the vertical pump 5 can be suppressed.

[0055] Between the pair of side surfaces 21 and the end surface 22, there are provided corner inclined surfaces 27 that are inclined toward the center in the width direction as they go downstream. This makes it possible to suppress swirling flows that may occur at the corners between the pair of side surfaces 21 and the end surface 22, thereby suppressing the generation of underwater vortices that extend from these walls to the suction port 6a of the vertical pump 5.

[0056] The lateral lower inclined surfaces 28 are connected to the bottom surface 20, the side surfaces 21, and the corner inclined surfaces 27, respectively, and are inclined outward in the width direction as they move upward from the bottom surface 20. This makes it possible to suppress swirling flows that may occur in the corners defined by the bottom surface 20, the pair of side surfaces 21, and the end surface 22, thereby effectively suppressing the generation of underwater vortices.

[0057] The rear lower inclined surface 29 is connected to the bottom surface 20, the end surface 22, and the corner inclined surface 27, and is inclined downstream as it moves upward from the bottom surface 20. This makes it possible to suppress swirling flows that may occur at the corners between the bottom surface 20 and the end surface 22, thereby effectively suppressing the generation of underwater vortices.

[0058] The end surface 22 is provided with a pillar portion 30 that protrudes upstream to form a triangular shape when viewed from above. This makes it possible to suppress swirling flows that may occur at the end surface 22, thereby effectively suppressing the generation of underwater vortexes.

[0059] The column portion 30 has a continuous surface 31 that is continuous with the rear inclined surface 30a and the rear lower inclined surface 29. This makes it possible to suppress a swirling flow that may occur between the rear inclined surface 30a and the protruding portion 25, thereby effectively suppressing the generation of underwater vortexes.

[0060] Other embodiments and various modifications of the present invention will be described below, but in these descriptions, points that are not particularly mentioned are the same as those in the first embodiment. In the drawings referred to below, the same elements as those in the first embodiment are given the same reference numerals.

[0061] Second embodiment 6, the water suction tank 10 of the second embodiment is significantly different from the water suction tank 10 of the first embodiment in that it is an open type without the top wall 18 shown in FIG.

[0062] In the second embodiment, a beam 35 is provided extending in the width direction, connected to the pair of side surfaces 21, so as to be spaced apart on the upstream side of the pump casing 6, and a chamfered surface 24 is formed on this beam 35 as in the first embodiment. The beam 35 is block-shaped with an upper surface located above the minimum water level LWL and a lower surface located below the minimum water level LWL. On the lower surface side of the beam 35 adjacent to the lower side of the minimum liquid level LWL, a chamfered surface 24 is formed which is connected to each of the pair of side surfaces 21, extends in the width direction, and gradually reduces the opening area between the bottom surface 20 toward the downstream side.

[0063] A beam 26 having a circular cross section is provided between the pump casing 6 and the end surface 22 so as to extend in the width direction. The upper end of the beam 26 is located above the minimum water level LWL, and the lower end of the beam 26 is located below the minimum water level LWL. In other words, the lower part of the beam 26 is adjacent to the lower side of the minimum water level LWL.

[0064] Third embodiment 7, the suction tank 10 of the third embodiment is an open type not including the top wall 18 shown in Fig. 2, similar to the suction tank 10 of the second embodiment. The third embodiment differs from the suction tank 10 of the second embodiment in that the cross-sectional shape of the beam 35 provided on the upstream side of the pump casing 6 and the cross-sectional shape of the beam 26 provided on the downstream side of the pump casing 6 are changed.

[0065] The beam 35 has a circular cross section, with the upper end of the beam 35 located above the lowest water level LWL and the lower end of the beam 35 located below the lowest water level LWL. More specifically, the beam 35 is provided so that the center of the beam 35 is located at the lowest water level LWL. The chamfered surface 24 is formed by the lower and upstream quarter of the outer circumferential surface of the beam 35. In other words, the chamfered surface 24 of the third embodiment is formed by a curved surface that gradually reduces the opening area between the bottom surface 20 toward the downstream side.

[0066] The beam 26 has an L-shaped cross section and includes a plate-shaped first portion 26a extending in the vertical direction and a plate-shaped second portion 26b extending in the inflow direction. The upper end of the first portion 26a is located above the lowest water level LWL, and the second portion 26b is located below the lowest water level LWL.

[0067] The water sump 10 of the second and third embodiments configured as described above can provide the same functions and effects as the first embodiment. Moreover, in these embodiments, since the upper ends of the pair of side surfaces 21 and the end surface 22 are open, any pump casing 6 that can be placed in the water sump 10 can be used. This improves the degree of freedom in the pump that can be applied.

[0068] The present invention is not limited to the configurations of the above-described embodiments, and various modifications are possible.

[0069] For example, the semi-closed water intake sump 10 of the first embodiment shown in FIG. 2 may be provided with a beam 26 having a circular cross section of the second embodiment shown in FIG. 6, or a beam 26 having an L-shaped cross section of the third embodiment shown in FIG. 7.

[0070] The beam 26 having a rectangular cross section according to the first embodiment shown in FIG. 2 may be provided in the open-type water suction tank 10 according to the second embodiment shown in FIG. 6 and the third embodiment shown in FIG.

[0071] The beam 26 having a circular cross section of the second embodiment shown in FIG. 6 may be provided in the water intake sump 10 of the third embodiment shown in FIG. 7, and the beam 26 having an L-shaped cross section of the third embodiment shown in FIG. 7 may be provided in the water intake sump 10 of the second embodiment shown in FIG. 6.

[0072] An arc-shaped chamfered surface 24 like the beam 35 of the third embodiment shown in FIG. 7 may be provided on the semi-closed suction tank 10 of the first embodiment shown in FIG. 2, or on the beam 35 of the second embodiment shown in FIG. 6.

[0073] If air-sucking vortices and underwater vortices can be suppressed, the configuration may be such that any of the protrusion 25, corner inclined surface 27, side lower inclined surface 28, rear lower inclined surface 29, pillar portion 30, and continuous surface 31 are not provided. [Explanation of symbols]

[0074] 1. Pump equipment 5 Vertical pump 6 Pump casing 6a Intake port 7 Rotation Axis 8 Impeller 10. Water suction tank (pump suction tank) 12 tank type 15 Bottom wall 16 side wall 17 End Wall 18 Ceiling wall 18a 1st wall 18b 2nd wall section 18c Third wall 18d Penetration 20 Bottom 21 Side 21a Water storage section 21b Drainage section 21c Continuous section 22 End face 23a 1st top surface 23b 2nd top surface 23c Continuous Surface 24 Chamfered surface 25 Protrusion 25a Ding slope 25b Side inclined surface 26 Beam 26a Part 1 26b Part 2 27 Corner slope 28 Lateral lower slope 28a Lower end 28b Upper end 28c, 28d downstream end 29 Rear lower slope 30 Pillar section 30a Rear slope 31 Continuous Surface 35 Beam LWL Lowest water level X Inflow direction Y Width direction Z depth direction

Claims

1. a bottom surface provided below the suction port with a gap therebetween and extending from an upstream side to a downstream side in a liquid inflow direction relative to the pump casing; A pair of side surfaces are provided at an interval in a width direction, which is a direction intersecting the inflow direction, with respect to the pump casing, and protrude upward from both sides of the bottom surface in the width direction, respectively; an end surface provided on the downstream side of the pump casing with a gap therebetween and closing the downstream side of each of the bottom surface and the pair of side surfaces; a chamfered surface that is provided on the upstream side of the pump casing with a gap therebetween, that is adjacent to a lower side of a minimum liquid level that can be discharged, that is connected to each of the pair of side surfaces, that extends in the width direction, and that gradually reduces an opening area between the chamfered surface and the bottom surface toward the downstream side; a beam provided between the pump casing and the end surface, adjacent to a lower side of the minimum liquid level and extending in the width direction; A pump suction tank.

2. The pump suction tank according to claim 1 , wherein the bottom surface is formed with a protruding portion that is inclined upward from the upstream side toward the downstream side of the pump casing.

3. The pump suction tank according to claim 2 , wherein the protruding portion has a pair of inclined side surfaces on both sides in the width direction, the inclined side surfaces being inclined downward and outward in the width direction.

4. Between the pair of side surfaces and the end surface, there are provided corner inclined surfaces inclined toward the center in the width direction as they proceed toward the downstream side, The pump suction tank according to claim 1 , wherein the beams are connected to the pair of inclined corner surfaces, respectively.

5. The pump suction tank according to claim 4 , further comprising: lower lateral inclined surfaces that are connected to the bottom surface, the side surface, and the corner inclined surface, and that incline outward in the width direction as they extend upward from the bottom surface to connect to the side surface.

6. 5. The pump suction tank according to claim 4, further comprising a rear lower inclined surface that is connected to the bottom surface, the end surface, and the corner inclined surface, and that slopes upward from the bottom surface toward the downstream side and is connected to the end surface.

7. The pump suction tank according to claim 6 , wherein the end surface is provided with a pillar portion extending in the up-down direction and protruding toward the upstream side so as to form a triangle when viewed from above.

8. The pillar portion has a pair of rear inclined surfaces that are inclined toward the width direction center toward the upstream side and whose tips are connected to each other, The pump suction tank according to claim 7 , further comprising a pair of continuous surfaces respectively continuing to the pair of rear inclined surfaces and the pair of rear lower inclined surfaces.

9. a top wall including a top surface connected to the upper ends of the pair of side surfaces and the end surface, The chamfered surface is formed by a portion of the top wall, The pump suction tank according to claim 1 , wherein the top wall is formed with a through-hole through which the pump casing passes.

10. The pump suction tank according to claim 1 , wherein upper ends of the pair of side surfaces and the end surface are open.

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