Pump

Abstract

To provide a pump capable of improving the workability in regulating the position of a swirl restraining device to be fixed to a pump casing.SOLUTION: A pump 20 includes a cylindrical lifting pipe 22 having a suction port 24b formed in the lower end, a first swirl restraining member 42 arranged on the downstream side of the lifting pipe 22 while being spaced therefrom, and extending along an axis line A, a plate-shaped second swirl restraining member 43 arranged on the lower side of the lifting pipe 22, and a plate-shaped intermediate plate 41 removably mounted to the lifting pipe 22, the first swirl restraining member 42 and the second swirl restraining member 43 being mounted to the lifting pipe 22 movably together with the intermediate plate 41.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a pump.

Background Art

[0002] In the suction tank of pump equipment, when the amount of water stored by drainage approaches the lowest water level, air suction vortices and underwater vortices that cause a decrease in pump efficiency and vibration may occur. In recent years, for the suction tank, there has been a demand to increase the approach flow velocity of water toward the pump casing (increase the flow velocity) and increase the flow rate. Therefore, the possibility of generating air suction vortices and underwater vortices harmful to the pump has been increasing. An air suction vortex is a vortex in which air is continuously or intermittently contained in the water flow from the water surface in the suction tank toward the suction port of the pump. An underwater vortex is a vortex in which gas (bubbles) due to cavitation is continuously or intermittently contained in the water flow from the bottom surface or side surface of the suction tank toward the suction port.

[0003] Patent Document 1 discloses a pump equipped with a vortex suppression device that suppresses the inflow of air suction vortices and underwater vortices into the pump casing. The vortex suppression device includes a plurality of vertical bars arranged on the downstream side in the direction in which water flows into the suction tank with respect to the pump casing, and a +-shaped suppression plate arranged at the lower end of the pump casing. The plurality of vertical bars are fixed to the outside of the pump casing at intervals and extend along the axis of the pump casing, and suppress by inhibiting the inflow of air suction vortices into the suction port. The suppression plate is fixed to the lower end of the pump casing so as to cross the suction port, and suppresses by inhibiting the inflow of underwater vortices into the suction port.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The shape of the suction tank may vary depending on the pump equipment. The locations where air suction vortices and underwater vortices occur vary depending on the shape of the suction tank and are difficult to predict. Therefore, in the vortex suppression device of Patent Document 1, it is necessary to individually adjust the fixed positions of the vertical rod and the suppression plate with respect to the pump casing according to the actual shape of the suction tank, that is, the locations where air suction vortices and underwater vortices occur. Therefore, there is room for improvement in the adjustability of the fixed position of the vortex suppression device in Patent Document 1.

[0006] An object of the present invention is to provide a pump capable of improving the workability of adjusting the fixed position of a vortex suppression device with respect to a pump casing.

Means for Solving the Problems

[0007] The present invention provides a pump comprising: a cylindrical lift pipe extending vertically in a suction tank and having a suction port formed at a lower end thereof; a first vortex suppression member disposed at a lower portion of the lift pipe corresponding to the lowest water level of the suction tank, spaced apart on a downstream side in a direction in which water flows into the suction tank, and extending along an axis of the lift pipe; a plate-shaped second vortex suppression member disposed below the lift pipe so as to cross the suction port; and a plate-shaped intermediate plate detachably attached to the lift pipe so as to protrude toward the downstream side and extending in a direction intersecting the axis. The first vortex suppression member and the second vortex suppression member are movably attached to the lift pipe together with the intermediate plate.

[0008] In this pump, the first vortex suppression member disposed at an interval on the downstream side of the lift pipe inhibits the flow of the air suction vortex from the water surface in the suction tank toward the suction port, and can suppress the inflow of the air suction vortex into the suction port. Further, the plate-shaped second vortex suppression member disposed below the lift pipe so as to cross the suction port inhibits the flow of the underwater vortex from the wall surface (bottom wall, side wall, lower end wall) of the suction tank toward the suction port, and can suppress the inflow of the underwater vortex into the suction port. Moreover, the plate-shaped intermediate plate protruding from the lift pipe toward the downstream side can assist in suppressing the inflow of the air suction vortex and the underwater vortex into the suction port. Therefore, the water in the suction tank can be efficiently discharged without containing harmful air and cavitation.

[0009] On the other hand, the first vortex suppression member and the second vortex suppression member are movably attached to the lift pipe together with the intermediate plate. Therefore, by adjusting the fixing position of the intermediate plate with respect to the lift pipe, the arrangement of the first vortex suppression member with respect to the suction tank and the posture of the second vortex suppression member can be adjusted together. As a result, the workability of adjusting the fixing positions of the first vortex suppression member and the second vortex suppression member can be improved, and the inflow of the air suction vortex and the underwater vortex into the suction port can be effectively suppressed.

Advantages of the Invention

[0010] In the present invention, the workability of adjusting the fixing position of the vortex suppression device with respect to the pump casing can be improved.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0013] (First Embodiment) Referring to FIG. 1, a horizontal shaft pump 20 according to a first embodiment of the present invention is fixed to a pump floor 4 of a building 1. The horizontal shaft pump 20 sucks rainwater or the like that has flowed into a water suction tank 2 of the building 1 and discharges it to a discharge tank (not shown). The building 1, the horizontal shaft pump 20, and the discharge tank constitute a pump facility.

[0014] The building 1 is constructed by placing concrete and includes a lower water suction tank 2 and an upper pump chamber 3. The water suction tank 2 is defined by a pump floor 4, a pair of side walls 5, a lower end wall 6, and a bottom wall 7. Among the water suction tank 2, the upstream side in the direction in which water flows (hereinafter referred to as the "inflow direction") F is an open communication portion 8, which is connected to an inflow water channel (not shown). The pump chamber 3 is defined by a pump floor 4, a pair of side walls 5, an upstream end wall 9, a downstream end wall 10, and a ceiling wall 11. The water suction tank 2 and the pump chamber 3 communicate spatially through a through hole 12 formed in the pump floor 4.

[0015] The horizontal shaft pump 20 includes a pump casing 21 including a suction port 24b, a main shaft 30, an impeller 31, and a motor (drive source) 33. This horizontal shaft pump 20 rotates the main shaft 30 via a speed reducer 33 by the operation of the motor 32, and the impeller 31 that rotates integrally with the main shaft 30 sucks water in the water suction tank 2 through the pump casing 21 and discharges it to the discharge tank.

[0016] Referring to FIG. 2, when the water is discharged to near the defined lowest water level LWL, the remaining water volume in the water suction tank 2 decreases, so the flow velocity due to drainage becomes faster especially around the pump casing 21. Therefore, an air suction vortex Va in which air is continuously or intermittently contained in the water flow from the water surface toward the suction port 24b, and an underwater vortex Vw in which gas (bubbles) due to cavitation is continuously or intermittently contained in the water flow from any of the walls 5, 6, 7 toward the suction port 24b can occur in the water suction tank 2.

[0017] In the present embodiment, in order to suppress the harmful air suction vortex Va and underwater vortex Vw from flowing into the horizontal axis pump 20 from the suction port 24b, a vortex suppression device 40 is fixedly arranged at the lower part of the pump casing 21 in a position-adjustable manner.

[0018] Hereinafter, the configurations of the pump casing 21, the main shaft 30, the impeller 31, the motor 32, and the vortex suppression device 40 will be specifically described.

[0019] Referring to FIG. 1, the pump casing 21 includes a lift pipe 22, a bent elbow 25, and a vane casing 26. The lift pipe 22 is arranged in the water suction tank 2 below the pump floor 4 through the through hole 12. The bent elbow 25 and the vane casing 26 are arranged in the pump chamber 3 above the pump floor 4.

[0020] Referring to FIG. 2, the lift pipe 22 includes a plurality (two in this embodiment) of straight pipes 23 and a suction bell 24, and extends vertically in the water suction tank 2.

[0021] The straight pipe 23 extends with a uniform diameter and is provided with annular flange portions (first flange portions) 23a protruding radially outward at the upper and lower ends respectively. A plurality of straight pipes 23 are liquid-tightly connected by fastening their flange portions 23a to each other with bolts and nuts. The overall length of each straight pipe 23 is set according to the lowest water level LWL of the water suction tank 2. Specifically, when the inside of the water suction tank 2 reaches the lowest water level LWL, the straight pipe 23 located at the lowermost side (hereinafter sometimes referred to as the "lower end straight pipe") has the upper flange portion 23a exposed to the air above the water surface and the lower flange portion 23a submerged. The overall length of each straight pipe 23 is set so that the lower end straight pipe 23 is in such a state when the lowest water level LWL is reached.

[0022] The suction bell 24 is in the shape of a conical cylinder that gradually expands downward. The suction bell 24 is provided with an annular flange portion (second flange portion) 24a protruding radially outward at the upper end. The open lower end of the suction bell 24 constitutes the suction port 24b. The suction bell 24 is liquid-tightly connected by fastening the flange portion 24a and the flange portion 23a of the lower end straight pipe 23 with bolts and nuts. In this state, the suction port 24b is located above the bottom wall 7 of the water suction tank 2 with a defined interval.

[0023] Referring to FIG. 1, the bent elbow 25 is a bent pipe with a central axis bent by 90 degrees. The bent elbow 25 is liquid-tightly connected to the flange portion 23a at the upper end of the lift pipe 22 with bolts and nuts.

[0024] The vane casing 26 is in the shape of a cylinder bulging radially outward so as to be generally elliptical spherical, and is liquid-tightly connected to the downstream end in the drainage direction of the bent elbow 25. Inside the vane casing 26, a bearing casing 26a is provided via a guide vane, and a bearing portion 26b is provided inside this bearing casing 26a.

[0025] In the pump casing 21 configured as described above, a water delivery pipe 27 composed of a plurality of pipes is connected to the downstream end of the vane casing 26. The downstream end of the water delivery pipe 27 penetrates the downstream end wall 10 and protrudes outside the building 1, and is piped into a discharge tank (not shown). A check valve 28 is provided in one of the plurality of pipes constituting the water delivery pipe 27 that is located within the pump chamber 3. However, the pump facility may be configured without the check valve 28.

[0026] Subsequently, referring to FIG. 1, the main shaft 30 is attached so as to penetrate the bend elbow 25 of the pump casing 21 and extend horizontally (sideways). The inner end of the main shaft 30 disposed within the pump casing 21 is rotatably supported by a bearing portion 26b. The outer end of the main shaft 30 disposed outside the pump casing 21 is connected to the motor 32 via a speed reducer 33.

[0027] The impeller 31 is attached to the vicinity of the inner end of the main shaft 30 in a non-rotatable relative manner. More specifically, the impeller 31 is disposed within the vane casing 26 and is attached to the main shaft 30 so as to be adjacent to the upstream side in the drainage direction among the bearing casings 26a.

[0028] The motor 32 is fixed on the pump floor 4 so as to be adjacent to the pump casing 21 and is controlled by a control unit (not shown). The speed reducer 33 is disposed between the pump casing 21 and the motor 32 and is connected to the output shaft of the motor 32 and the main shaft 30, respectively. When the motor 32 is operated with the inside of the pump casing 21 being full of water, the main shaft 30 is rotated via the speed reducer 33, and the impeller 31 rotates integrally with the main shaft 30. Thereby, the water in the suction tank 2 is sucked into the pump casing 21 from the suction port 24b and discharged to the discharge tank (drainage operation).

[0029] Referring to FIGS. 2 to 5, the vortex suppression device 40 suppresses the generation of the air suction vortex Va and the underwater vortex Vw, or suppresses the inflow of the generated air suction vortex Va and underwater vortex Vw into the suction port 24b. This vortex suppression device 40 is composed of two intermediate plates 41A and 41B, two first vortex suppression members 42, and one second vortex suppression member 43.

[0030] Two first vortex suppression members 42 and one second vortex suppression member 43 are attached to the intermediate plates 41A and 41B. Thereby, by adjusting the fixed positions of the intermediate plates 41A and 41B with respect to the lift pipe 22, the arrangement of the first vortex suppression member 42 and the posture of the second vortex suppression member 43 with respect to the water suction tank 2 can be adjusted together.

[0031] The intermediate plates 41A and 41B are provided for attaching two first vortex suppression members 42 and one second vortex suppression member 43 to the lift pipe 22. Among them, the lower intermediate plate 41A also has a function of assisting in suppressing the inflow of the air suction vortex Va and the underwater vortex Vw into the suction port 24b. The intermediate plates 41A and 41B are detachably fixed to the lift pipe 22 so as to protrude downstream in the inflow direction F.

[0032] The intermediate plates 41A and 41B are each constituted by the same fan-shaped plate bodies having inner peripheral edges extending along the outer peripheral surface of the lift pipe 22 when viewed from above. These intermediate plates 41A and 41B are arranged at intervals in the vertical direction with respect to the lift pipe 22 and extend in the horizontal direction intersecting the axis A of the lift pipe 22. However, the fixed angles of the intermediate plates 41A and 41B with respect to the lift pipe 22 can be changed as necessary. Also, the shapes of the intermediate plates 41A and 41B may be other than fan-shaped, or may be provided with a large number of holes as long as they are smaller than the diameter of the air suction vortex Va.

[0033] More specifically, insertion holes 41a corresponding to the insertion holes 23b and 24c formed in the flange portions 23a and 24a of the lift pipe 22 are respectively provided in the inner peripheral portions of the intermediate plates 41A and 41B. The lower intermediate plate 41A is disposed so as to overlap the lower surface of the flange portion 24a of the suction bell 24, and is fastened together with the flange portion 23a of the lower end straight pipe 23 by bolts and nuts. That is, the intermediate plate 41A is fixed to the lift pipe 22 so as to be in a state of being submerged between the water surface and the suction port 24b of the lift pipe 22 when the water level in the suction tank 2 reaches the lowest water level LWL. The upper intermediate plate 41B is disposed so as to overlap the upper surface of the flange portion 23a of the straight pipe 23 directly above the lower end straight pipe 23, and is fastened together with the flange portion 23a of the lower end straight pipe 23 by bolts and nuts. That is, the intermediate plate 41B is fixed to the lift pipe 22 so as to be exposed from the water surface into the air when the water level in the suction tank 2 reaches the lowest water level LWL.

[0034] Mounting holes 41b for attaching two first vortex suppression members 42 are provided in the intermediate plates 41A and 41B at intervals in the circumferential direction around the axis A of the lift pipe 22. Further, the lower intermediate plate 41A is provided with a engaging groove 41c for engaging one second vortex suppression member 43. The engaging groove 41c is provided so as to be located at the center between a pair of mounting holes 41b, and extends radially outward from the inner peripheral portion of the intermediate plate 41A. The engaging groove 41c is not provided in the upper intermediate plate 41B.

[0035] As most clearly shown in FIG. 3, the two first vortex suppression members 42 inhibit the flow of two air suction vortices Va that may be generated on the downstream side of the lift pipe 22 by the water flow that circulates around the lift pipe 22 from the upstream side to the downstream side in the suction tank 2, and suppress the inflow into the suction port 24b of the lift pipe 22. Referring to FIGS. 2 to 5, the first vortex suppression member 42 is disposed at an interval on the downstream side in the inflow direction F with respect to the lower portion of the lift pipe 22 corresponding to the lowest water level LWL of the suction tank 2, more specifically, the lower end straight pipe 23, and extends along the axis A of the lift pipe 22.

[0036] The two first vortex suppression members 42 are arranged at intervals in the circumferential direction around the axis A by being attached to the mounting holes 41b of the intermediate plates 41A and 41B. The lower end 42a of each first vortex suppression member 42 protrudes below the lower intermediate plate 41A and is located in the upper vicinity of the suction port 24b which is the lower end of the suction bell 24. The upper end 42b of each first vortex suppression member 42 protrudes above the upper intermediate plate 41B, that is, above the water surface of the lowest water level LWL, and is located in the generally central portion in the vertical direction of the lift pipe 22.

[0037] Each first vortex suppression member 42 is a solid rod with a uniform diameter. However, the first vortex suppression member 42 may be constituted by a hollow rod. Each first vortex suppression member 42 is fixed by passing through the mounting hole 41b and welding to the intermediate plates 41A and 41B. However, a flange portion may be provided on each first vortex suppression member 42, and the first vortex suppression member 42 may be fixed to the intermediate plates 41A and 41B respectively by bolting the flange portion to the intermediate plates 41A and 41B. Further, each first vortex suppression member 42 may be constituted by three rods, a flange portion may be provided on each rod, and a single first vortex suppression member 42 composed of the three rods may be fixed to the intermediate plates 41A and 41B by bolting the flange portion to the intermediate plates 41A and 41B.

[0038] The second vortex suppression member 43 suppresses the inflow of the underwater vortex Vw and the air suction vortex Va into the suction port 24b by inhibiting the swirling flow below the lift pipe 22. The second vortex suppression member 43 is in a flat plate shape, is located at an interval below the suction port 24b of the lift pipe 22, and includes a main body portion 43a that extends along the inflow direction F so as to cross the suction port 24b. The overall width of the main body portion 43a from the upstream side to the downstream side in the inflow direction F is larger than the diameter of the suction port 24b of the suction bell 24.

[0039] The second vortex suppression member 43 includes a pair of engaging portions 43b that project upward from both ends in the width direction of the main body portion 43a. One of the pair of engaging portions 43b is inserted into the engaging groove 41c of the lower intermediate plate 41A. Thereby, the second vortex suppression member 43 can move together with the movement of the intermediate plate 41A. Further, the pair of engaging portions 43b are hooked on the flange portion 23a below the lower end straight pipe 23 and fastened by bolts and nuts. Referring to FIGS. 4 and 5, each engaging portion 43b includes an arm portion 43c and an engaging portion main body 43d.

[0040] The arm portion 43c projects upward from the main body portion 43a and extends along the axis A outside the lift pipe 22. The lateral width of the lower portion of the arm portion 43c gradually increases toward the inner side in the width direction of the main body portion 43a within a range that does not interfere with the suction bell 24. The thickness of the arm portion 43c in the direction orthogonal to the width direction in which the main body portion 43a extends is thinner than the groove width of the engaging groove 41c of the intermediate plate 41A.

[0041] The engaging portion main body 43d projects from the upper end of the arm portion 43c toward the inner side in the width direction of the main body portion 43a. The width of the engaging portion main body 43d in the direction orthogonal to the width direction in which the main body portion 43a extends is wider than the thickness of the arm portion 43c and wider than the groove width of the engaging groove 41c of the intermediate plate 41A. Thereby, in a state where the arm portion 43c is inserted into the engaging groove 41c, the second vortex suppression member 43 is inseparably engaged with the intermediate plate 41A. The interval between the pair of engaging portion main bodies 43d is larger than the outer diameter of the lower end straight pipe 23. The pair of engaging portion main bodies 43d are each provided with an insertion hole 43e corresponding to the insertion hole 23b of the lower end straight pipe 23.

[0042] In the horizontal axis pump 20 with the vortex suppression device 40 fixed in this way, as will be described in detail below, the generation of the air suction vortex Va and the underwater vortex Vw can be suppressed, or the inflow of the generated air suction vortex Va and underwater vortex Vw into the suction port 24b can be suppressed.

[0043] The air suction vortex Va can occur in the region on the downstream side of the lift pipe 22 in the water suction tank 2. The generation of the air suction vortex Va is due to the swirling flow caused by the separation of the flow from the lift pipe 22. This air suction vortex Va has its flow toward the suction port 24b inhibited by the first vortex suppression member 42 disposed near the generation location. If it cannot be completely inhibited by the first vortex suppression member 42, the air suction vortex Va is inhibited by the lower intermediate plate 41A. As a result, the inflow of the air suction vortex Va into the suction port 24b is suppressed.

[0044] The first underwater vortex Vw can occur on the bottom wall 7 of the water suction tank 2. The generation of the underwater vortex Vw on the bottom wall 7 is due to the swirling flow that can occur due to the velocity difference of the water flow toward the axis A of the lift pipe 22 in the width direction of the water suction tank 2, which is a direction intersecting the inflow direction F. The swirling of the underwater vortex Vw on this bottom wall 7 is inhibited by the second vortex suppression member 43 below the lift pipe 22. As a result, the inflow of the underwater vortex Vw from the bottom wall 7 into the suction port 24b is suppressed.

[0045] The second underwater vortex Vw can occur at the lower part of the lower end wall 6 of the water suction tank 2. The generation of the underwater vortex Vw on the lower end wall 6 is due to the swirling flow from the upper side to the lower side caused by contact with the lower end wall 6. The generation of the underwater vortex Vw itself on the lower end wall 6 is suppressed by the suppression of the flow velocity magnitude and the swirling flow by the lower intermediate plate 41A.

[0046] The third underwater vortex Vw can occur at the lower part of the side wall 5 of the suction tank 2. The generation of the underwater vortex Vw at the side wall 5 is caused by the difference in the water flow velocities between the upper layer region and the lower layer region in the suction tank 2. As shown by the rightward arrow in FIG. 2, the water flow velocity in the suction tank 2 gradually decreases from the upper side to the lower side (the length of the arrow corresponds to the flow velocity). The generation of the underwater vortex Vw itself at the side wall 5 is suppressed by the lower intermediate plate 41A. Specifically, the intermediate plate 41A can suppress the swirling flow from the upper side to the lower side as described above, and approximate a state where the downstream upper layer region of the suction tank 2 is partially blocked. Thereby, the water in the upper layer region can be made to flow downward in the direction indicated by the solid line instead of the direction indicated by the broken line in FIG. 2 upstream of the lift pipe 22. As a result, since the difference in the flow velocity between the upper layer region and the lower layer region can be eliminated, the generation of the underwater vortex Vw itself at the side wall 5 can be suppressed.

[0047] As described above, in order to suppress the inflow of the air suction vortex Va and the underwater vortex Vw into the suction port 24b, the vortex suppression device 40 of the present embodiment is further configured as follows.

[0048] Referring to FIG. 3, a pair of first vortex suppression members 42 adjacent to each other in the circumferential direction are arranged with a space α therebetween in the circumferential direction. If this space α is made too large or too small, since it is separated from the two air suction vortices Va that can occur downstream of the lift pipe 22, the inflow of the air suction vortex Va into the suction port 24b cannot be suppressed. Therefore, the space α between the pair of first vortex suppression members 42 is preferably set in the range of 60 degrees or more and 120 degrees or less, and is set to 90 degrees in the present embodiment.

[0049] The first vortex suppression member 42 is arranged at an interval outside the lift pipe 22. If this interval is too large or too small, it will be away from the two air suction vortices Va that may occur on the downstream side of the lift pipe 22, so the inflow of the air suction vortex Va into the suction port 24b cannot be suppressed. Therefore, assuming the inner peripheral surface of the lift pipe 22 has a diameter D, the distance R1 from the axis A to the center of the first vortex suppression member 42 is preferably set in the range of 0.8D or more and 1.3D or less, and is set to 1.0D in this embodiment. The diameter of the first vortex suppression member 42 is preferably set in the range of 0.05 or more and 0.20D or less, and is set to 0.125D in this embodiment. In this specification, "D" described below also means the inner peripheral diameter of the lift pipe 22.

[0050] When the first vortex suppression member 42 cannot suppress the inflow of the air suction vortex Va into the suction port 24b, the intermediate plate 41A suppresses the inflow of the air suction vortex Va into the suction port 24b (see FIG. 2). Further, the intermediate plate 41A suppresses the generation of the underwater vortex Vw by suppressing the swirling flow at the lower end wall 6 of the water suction tank 2. If the distance R2 from the axis A of the lift pipe 22 to the outer peripheral edge of the intermediate plate 41A, that is, the radius of the intermediate plate 41A, is made excessively small, the inhibition of the air suction vortex Va and the suppression of the generation of the underwater vortex Vw at the lower end wall 6 cannot be achieved. On the other hand, if the radius of the intermediate plate 41A is made excessively large, the balance of the lift pipe 22 to which the vortex suppression device 40 is fixed will be excessively deteriorated, and the area on the downstream side of the lift pipe 22 in the water suction tank 2 will become excessively large. Therefore, the aforementioned distance R2 corresponding to the radius of the intermediate plate 41A is preferably set in the range of 1.0D or more and 1.5D or less, and is set to 1.2D in this embodiment.

[0051] There is a gap S1 between the intermediate plate 41A and the lower end wall 6. If the gap S1 is made excessively large, the area where the air suction vortex Va can be generated becomes wider, and it becomes difficult to suppress the generation of the underwater vortex Vw on the lower end wall 6 of the water suction tank 2. On the other hand, if the gap S1 is made excessively small, it may become difficult to attach to the existing pump casing 21. Therefore, the gap S1 between the intermediate plate 41A and the lower end wall 6 is preferably set to be 0.05D or more and 0.1D or less, and is set to 0.075D in this embodiment.

[0052] Referring to FIG. 2, the suction port 24b of the lift pipe 22 is positioned with a defined interval S0 from the bottom wall 7 of the water suction tank 2. The lowest water level LWL of the water suction tank 2 is set to be 1.6D or more and 2.5D or less, and is set to 1.9D in this embodiment. However, the lowest water level LWL of the water suction tank 2 may be set to 1.6D or 1.9D. Also, the interval S0 between the suction port 24b of the lift pipe 22 and the bottom wall 7 of the water suction tank 2 is preferably set in the range of 0.6D or more and 0.8D or less, and is set to 0.7D in this embodiment. Note that the diameter of the suction port is preferably set in the range of 1.3D or more and 1.4D or less, and is set to 1.36D in this embodiment.

[0053] On the other hand, the second vortex suppression member 43 is arranged with an interval S2 from the bottom wall 7 of the water suction tank 2. If the interval S2 between the second vortex suppression member 43 and the bottom wall 7 is made excessively large, the flow of the underwater vortex Vw generated on the bottom wall 7 may be inhibited, and there may be a possibility that the inflow of the underwater vortex Vw into the suction port 24b cannot be suppressed. If the interval S2 between the second vortex suppression member 43 and the bottom wall 7 is made excessively small, it may become difficult to attach to the existing pump casing 21. Therefore, the interval S2 between the second vortex suppression member 43 and the bottom wall 7 is preferably set in the range of 0.05D or more and 0.10D or less, and is set to 0.07D in this embodiment.

[0054] In the vortex suppression device 40 configured in this way, the generation of the air suction vortex Va and the underwater vortex Vw can be suppressed, or the inflow of the generated air suction vortex Va and underwater vortex Vw into the suction port 24b can be suppressed.

[0055] Moreover, regardless of whether it is newly installed or existing, the intermediate plates 41A, 41B, the first vortex suppression member 42, and the second vortex suppression member 43 can be moved together and attached to the pump casing 21 as shown in FIGS. 2 and 3.

[0056] On the other hand, when adjusting the arrangement of the first vortex suppression member 42 and the posture of the second vortex suppression member 43 according to the actual suction tank 2, remove the bolts and nuts fastening the intermediate plates 41A, 41B and the second vortex suppression member 43, and as shown in FIG. 6, rotate the intermediate plates 41A, 41B to an appropriate angular position, and re-fasten the intermediate plates 41A, 41B including the second vortex suppression member 43 with bolts and nuts. Thereby, the first vortex suppression member 42 and the second vortex suppression member 43 can be rotated (moved) together to adjust the arrangement and posture.

[0057] The horizontal axis pump 20 configured as described above has the following characteristics.

[0058] The flow of the air suction vortex Va is inhibited by the first vortex suppression member 42 arranged at an interval on the downstream side of the lift pipe 22, and the inflow of the air suction vortex Va into the suction port 24b can be suppressed. Further, the flow of the underwater vortex Vw from the walls 5 to 7 of the suction tank 2 toward the suction port 24b is inhibited by the plate-shaped second vortex suppression member 43 arranged below the lift pipe 22 so as to cross the suction port 24b, and the inflow of the underwater vortex Vw into the suction port 24b can be suppressed. Moreover, the inflow of the air suction vortex Va and the underwater vortex Vw into the suction port 24b can be supplementarily suppressed by the plate-shaped intermediate plate 41A protruding from the downstream side of the lift pipe 22. Therefore, the water in the suction tank 2 can be efficiently discharged without containing harmful air and cavitation.

[0059] On the other hand, the first vortex suppression member 42 and the second vortex suppression member 43 are attached to the lift pipe 22 so as to be movable together with the intermediate plate 41A. Therefore, by adjusting the fixed position of the intermediate plate 41A with respect to the lift pipe 22, the arrangement of the first vortex suppression member 42 and the posture of the second vortex suppression member 43 with respect to the suction tank 2 can be adjusted together. As a result, the workability of adjusting the fixed positions of the first vortex suppression member 42 and the second vortex suppression member 43 can be improved, and the inflow of the air suction vortex Va and the underwater vortex Vw into the suction port 24b can be effectively suppressed.

[0060] The intermediate plate 41A is fastened together with the flange portion 23a of the straight pipe 23 and the flange portion 24a of the suction bell 24. Thereby, by adjusting the fastening position of the intermediate plate 41A to the flange portions 23a and 24a, the arrangement of the first vortex suppression member 42 and the posture of the second vortex suppression member 43 with respect to the suction tank 2 can be easily and surely adjusted.

[0061] The first vortex suppression member 42 is attached so as to penetrate through a plurality of intermediate plates 41A and 41B fixed at intervals in the vertical direction, and the second vortex suppression member 43 is engaged with the lowermost intermediate plate 41A. Therefore, the first vortex suppression member 42 to which a large load is applied can be surely arranged in a state of opposing the water flow, and the second vortex suppression member 43 to which only a small load is applied can be surely arranged with a simple engagement structure.

[0062] A plurality of first vortex suppression members 42 are attached to the intermediate plate 41A at intervals in the circumferential direction around the axis A. Therefore, the inflow of a plurality of air suction vortices Va that may be generated in the suction tank 2 into the suction port 24b can be individually suppressed by the plurality of first vortex suppression members 42.

[0063] The first vortex suppression members 42 adjacent to each other in the circumferential direction are arranged at intervals of 60 degrees or more and 120 degrees or less. By doing so, two air suction vortices Va that may be generated by the water flow that wraps around the lift pipe 22 and heads downstream in the suction tank 2 can be inhibited by the first vortex suppression members 42 adjacent to each other in the circumferential direction, and the inflow into the suction port 24b can be suppressed.

[0064] With respect to the diameter D of the lift pipe 22, the distance R1 from the axis A to the center of the first vortex suppression member 42 is set in the range of 0.8D or more and 1.3D or less. Thereby, the air suction vortex Va that may occur around the lift pipe 22 is inhibited by the first vortex suppression member 42, and the inflow into the suction port 24b can be reliably suppressed.

[0065] With respect to the diameter D of the lift pipe 22, the distance R2 from the axis A to the outer peripheral edge of the intermediate plate 41A is set in the range of 1.0D or more and 1.5D or less. Thereby, the air suction vortex Va that may occur around the lift pipe 22 is inhibited by the intermediate plate 41A, and the inflow into the suction port 24b can be reliably suppressed. Moreover, the generation of the underwater vortex Vw at the lower end wall 6 of the water suction tank 2 can be suppressed.

[0066] Hereinafter, other embodiments and various modifications of the present invention will be described. In these descriptions, points not particularly mentioned are the same as those in the first embodiment. In the drawings referred to below, the same reference numerals are given to the same elements as those in the first embodiment.

[0067] (Second Embodiment) Referring to FIG. 7, the horizontal axis pump 20 of the second embodiment is different from the first embodiment in that the intermediate plate 41B above the vortex suppression device 40 is constituted by a pair of split plates. Each intermediate plate 41B is in the shape of a sector, and the formation angle range around the axis A is set as small as possible within the range where the first vortex suppression member 42 can be joined.

[0068] The horizontal axis pump 20 of the second embodiment configured in this way can obtain the same operations and effects as the horizontal axis pump 20 of the first embodiment. Moreover, since the intermediate plate 41B exposed from the water surface in the state of being lowered to the lowest water level LWL is constituted by a hollowed-out split plate, when the water level in the water suction tank 2 is higher than the intermediate plate 41B, an unintended load can be suppressed from being applied.

[0069] Note that the present invention is not limited to the configuration of the above-described embodiment, and various modifications are possible.

[0070] For example, the vortex suppression device 40 may be composed of one intermediate plate 41A, two first vortex suppression members 42, and one second vortex suppression member 43. That is, the intermediate plate may be composed only of the lower side that is submerged in the state of being lowered to the lowest water level LWL. Further, the intermediate plate may be composed of three or more.

[0071] The first vortex suppression member 42 may be composed of only one, or may be composed of three or more. The second vortex suppression member 43 may be composed of two or more plate bodies and may be arranged to extend in directions intersecting each other.

[0072] As shown in FIG. 8, the pump may be a vertical shaft pump in which the main shaft 30 extends in the vertical direction along the lift pipe 22, and an impeller 31 is attached to the lower end of the main shaft 30. In this case, instead of the lower end straight pipe 23 shown in FIG. 2, a vane casing 26 having flange portions (first flange portions) 26a at both ends is used for the lift pipe 22. Then, a suction bell 24 is fastened to the vane casing 26, and the impeller 31 is disposed below the vane casing 26. In other words, the vortex suppression device 40 can be applied to any pump having a lift pipe 22 extending in the vertical direction.

Explanation of Signs

[0073] 1 Building 2 Suction tank 3 Pump chamber 4 Pump floor 5 Side wall 6 Lower end wall 7 Bottom wall 8 Communication part 9 Upstream end wall 10 Downstream end wall 11 Ceiling wall 12 Through hole 20 Horizontal shaft pump 21 Pump casing 22 Lift pipe 23 Straight pipe 23a Flange portion 24 Suction bell 24a flange portion 24b suction port 25 bend elbow 26 vane casing 26a bearing casing 26b bearing portion 27 water supply pipe 28 stop valve 30 main shaft 31 impeller 32 motor 33 speed reducer 23b insertion hole 24c insertion hole 40 vortex suppression device 41 intermediate plate 41a insertion hole 41b mounting hole 41c engaging groove 42 first vortex suppression member 42a lower end 42b upper end 43 second vortex suppression member 43a main body portion 43b engaging portion 43c arm portion 43d engaging portion main body 43e insertion hole A axis of the water lift pipe D inner diameter of the water lift pipe LWL lowest water level of the suction tank F inflow direction of the suction tank Va air suction vortex Vw underwater vortex

Claims

1. A pump comprising: a cylindrical lift pipe extending vertically within a water suction tank and having a suction port formed at its lower end; a first vortex suppression member disposed at a lower portion of the lift pipe corresponding to the lowest water level of the water suction tank, spaced apart on the downstream side in a direction in which water flows into the water suction tank, and extending along the axis of the lift pipe; a plate-shaped second vortex suppression member disposed below the lift pipe so as to cross the suction port; a plate-shaped intermediate plate detachably attached to the lift pipe so as to protrude toward the downstream side and extending in a direction intersecting the axis; wherein the first vortex suppression member and the second vortex suppression member are movably attached to the lift pipe together with the intermediate plate.

2. The lift pipe has a straight pipe including a first flange portion and a suction bell including a second flange portion and the suction port, and the suction bell is connected to the lower side of the straight pipe by fastening the first flange portion and the second flange portion, The pump according to claim 1, wherein the intermediate plate is fastened together with the first flange portion and the second flange portion.

3. A plurality of the intermediate plates are fixed to the lift pipe at intervals in the vertical direction, the first vortex suppression member is attached through the plurality of intermediate plates, the second vortex suppression member is attached to the lowermost intermediate plate, The pump according to claim 1 or 2.

4. The pump according to claim 1 or 2, wherein a plurality of the first vortex suppression members are attached to the intermediate plate at intervals in the circumferential direction around the axis.

5. The pump according to claim 4, wherein the circumferentially adjacent first vortex suppression members are arranged at intervals of 60 degrees or more and 120 degrees or less.

6. The pump according to claim 1 or 2, wherein when the inner peripheral surface of the lift pipe has a diameter D, the distance R1 from the axis to the center of the first vortex suppression member satisfies the following: 0.8D ≤ R1 ≤ 1.3D D: Diameter of the inner peripheral surface of the lift pipe R1: Distance from the axis of the lift pipe to the center of the first vortex suppression member

7. The pump according to claim 1 or 2, wherein when the inner peripheral surface of the lift pipe has a diameter D, the distance R2 from the axis to the outer peripheral edge of the intermediate plate satisfies the following: 1.0D ≤ R2 ≤ 1.5D D: Diameter of the inner peripheral surface of the lift pipe R2: Distance from the axis of the lift pipe to the outer peripheral edge of the intermediate plate

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