JP5345123B2 - Vertical shaft pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertical shaft pump of simple structure capable of remarkably restricting outbreaks of an underwater whirl and an air suction whirl without deteriorating the drainage efficiency. <P>SOLUTION: The vertical shaft pump includes: a lifting pipe 11; and a main spindle 15, which extends in the lifting pipe 11 and to which an impeller 19 is fixed on a lower end side thereof. The vertical shaft pump also includes: a nearly conic-cylindrical outside trumpet part 24 formed to be enlarged in diameter as it comes close to a lower end on a lower side of the impeller 19 on a lower end side of the lifting pipe 11; and three or more whirl preventing ribs 31 radially extending in the outside trumpet part 24 outward from the axis of the outside trumpet part 24 and projecting downward from a lower opening part 24c of the outside trumpet part 24. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a vertical shaft pump.

Non-Patent Document 1 states that the main pump installed in the pump equipment is excellent in startability, reliability, and maintainability in a form suitable for installation conditions, and has an operation performance corresponding to fluctuations in water level and flow rate. It is prescribed. As one means for realizing this regulation, it is described that a semi-closed water-absorbing tank or an open-type water-absorbing tank with an eddy current preventing plate is appropriately adopted for a pump with a discharge amount of 10 m ³ / s or less. ing.

  Patent Document 1 describes a pump vortex preventing device for the purpose of preventing the occurrence of air suction vortices and underwater vortices when pumping up water in a water absorption tank. In this pump vortex prevention device, a sub-flow channel forming body that is substantially concentric is disposed on the outer peripheral portion of the lower trumpet portion having a suction port, and the sub-flow Forming a road. As a result, the flow from the water surface side toward the suction port is divided into a main flow and a sub-flow that flows along the sub-flow path, so that a strong local downward flow that causes an air suction vortex is not generated. Moreover, the suction cone which protrudes in the mountain shape below the suction inlet is arrange | positioned, and generation | occurrence | production of underwater vortex is prevented with this suction cone.

  Patent Document 2 describes a vertical shaft pump in which an inner trumpet portion having a substantially conical cylindrical shape is disposed inside a trumpet portion having a suction port, and a flow path is formed therebetween. The inner trumpet portion is coupled to the inner side of the outer trumpet portion by radially projecting ribs.

  In these Patent Documents 1 and 2, instead of the vortex prevention plate (+ -shaped baffle) and cone to be constructed in the water absorption tank, the air suction is performed by the sub-flow channel forming body, the suction cone or the inner trumpet at the lower end of the pump casing. Generation of vortices and underwater vortices can be suppressed. Therefore, it can be applied to either a newly constructed machine station or an existing machine station without carrying out a large-scale construction on the water absorption tank, and the rules described in Non-Patent Document 1 can be strictly observed at a low cost. However, these eddy current prevention measures still have room for improvement in terms of suppressing the generation of vortices.

Supervision Ministry of Land, Infrastructure, Transport and Tourism General Policy Bureau construction construction planning section "pumping and drainage pump equipment technical standard (draft) same commentary pumping and drainage pump equipment design guideline (draft) same commentary" editing and publication office River Pump Facility Technical Association, 2001 Published February, page 4,

Japanese Patent No. 4117699 Japanese Patent No. 3735602

  An object of the present invention is to provide a vertical pump that can significantly suppress the generation of submerged vortices and air suction vortices with a simple configuration without reducing drainage efficiency.

In order to solve the above-mentioned problems, the vertical shaft pump according to the present invention is a vertical shaft pump comprising a pumping pipe and a main shaft extending in the pumping pipe and having an impeller fixed to the lower end side. A substantially conical cylindrical outer trumpet that is provided on the lower side of the impeller and expands toward the lower end, and is provided on the inner side of the outer trumpet, extends along the axis of the outer trumpet, and toward the lower end. A substantially conical cylindrical axial trumpet portion projecting radially outward so as to gradually expand in diameter , and projecting radially outward from the outer surface of the axial trumpet portion , and the outer trumpet portion It is set as the structure provided with the 3 or more eddy current prevention rib which protrudes downward from the lower end opening part of this.

  In this vertical shaft pump, three or more eddy current preventing ribs that project radially and project downward from the lower end opening are connected to the inner side of the outer trumpet portion. And the eddy current prevention rib can aim at a significant cost reduction compared with the + character baffle and cone which require large construction. In addition, the vortex prevention rib is installed inside the outer trumpet at the lower end of the pumping pipe, so it can be installed securely not only in the vertical pump installed in the newly constructed machine station, but also in the existing machine station. it can. And since it can position easily along the axis line of a pumping pipe, compared with the case where a + character baffle and a cone are constructed in a water absorption tank, the workability regarding installation accuracy can also be improved significantly.

In this vertical shaft pump, it extends downward between the outer trumpet portion and the axial trumpet portion at a predetermined interval, and the lower end opening is located below the lower end opening of the outer trumpet portion. An inner trumpet portion is provided, the outer and inner trumpet portions are connected by three or more connecting ribs projecting radially outward from the inner trumpet portion, and the eddy current preventing rib is connected to the inner side of the inner trumpet portion. It is preferable to connect to. In this case, it is preferable that the connecting rib protrudes downward from the lower end opening of the outer trumpet portion . If so this, the flow path in the outer wrapper portion is defined by the axis trumpet portion (axial center portion) or the inner wrapper portion. As a result, the generation of underwater vortices and air suction vortices can be reliably suppressed and the suction performance can be improved by the synergistic effect with the vortex preventing ribs.
Or it is preferable to connect the said eddy current prevention rib to the inner side of the said outer trumpet part.

  In the vertical shaft pump of the present invention, three or more vortex-preventing ribs that project radially and project downward from the lower end opening are connected to the inner side of the outer trumpet, thereby suppressing the generation of underwater vortices with a simple configuration. it can. And since a vortex prevention rib does not require large-scale construction compared with the case where + character baffle and cone are constructed in a water absorption tank, it can aim at a significant cost reduction. In addition, the vortex preventing rib can be reliably disposed not only in a vertical shaft pump installed in a newly constructed machine station, but also in an existing machine station. Furthermore, by providing the shaft center trumpet part and the inner trumpet part inside the outer trumpet part, the generation of underwater vortices and air suction vortices can be greatly suppressed by a synergistic effect with the vortex preventing ribs.

It is sectional drawing which shows the vertical shaft pump of 1st Embodiment of this invention. It is a principal part expanded sectional view of FIG. It is the perspective view which fractured | ruptured a part of FIG. FIG. 4 is an exploded perspective view of FIG. 3. It is a principal part expanded sectional view of the vertical shaft pump of 2nd Embodiment. It is the perspective view which fractured | ruptured a part of FIG. FIG. 7 is an exploded perspective view of FIG. 6. It is a principal part expanded sectional view of the vertical shaft pump of a 1st reference example . It is the perspective view which fractured | ruptured a part of FIG. FIG. 10 is an exploded perspective view of FIG. 9. It is a principal part expanded sectional view of the vertical shaft pump of the 2nd reference example . It is the perspective view which fractured | ruptured a part of FIG. It is a disassembled perspective view of FIG. It is sectional drawing which shows the vertical shaft pump of 3rd Embodiment . It is the chart which compared the performance of the conventional vertical pump and the vertical pump of this invention.

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

(First embodiment)
1 to 4 show a vertical pump according to a first embodiment of the present invention. This vertical shaft pump drains the water stored in the water absorption tank 1 to a discharge water tank on the downstream side. In the vertical shaft pump of this embodiment, the swirl prevention rib 31, the shaft center trumpet portion 30, and the inner trumpet portion 26 are disposed inside the outer trumpet portion 24 of the pump casing 10, so that submerged vortex and air suction during operation are provided. It greatly suppresses the generation of vortices.

  As shown in FIG. 1, the vertical shaft pump of this embodiment is a barrel pump in which a water absorption tank 1 is formed inside by covering an outer peripheral portion with a barrel casing 2. The barrel casing 2 is provided with an inflow port 3 for allowing water to flow in, and the inflow port 3 is connected to a sewage facility on the upstream side. The water flowing in from the inflow port 3 is temporarily stored in the water absorption tank 1 in the barrel casing 2, pumped by a vertical shaft pump, and discharged downstream.

  The pump casing 10 is provided with a straight tubular pumping pipe 11 extending in the vertical direction. A discharge elbow 12 for changing the water flow from the vertical direction to the horizontal direction is connected to the pumping pipe 11 at the upper end. The discharge elbow 12 is liquid-tightly connected to the pump pipe 11 and the barrel casing 2 at the lower end, and the discharge port 13 at the upper end is liquid-tightly connected to a pipe (not shown) to the discharge water tank side. Further, a vane casing 14 is connected to the lower end of the pumping pipe 11, and a bell mouth 21 described later is connected to the lower end of the vane casing 14.

  A main shaft 15 is disposed in the pump casing 10 so as to extend through the pumping pipe 11 in the vertical direction. The lower end side of the main shaft 15 is rotatably supported by a first bearing 16 located in the vane casing 14, and the upper end side is rotatably supported by a second bearing 18 located on the discharge elbow 12. The first bearing 16 is disposed in a holder 17 connected to the vane casing 14. The second bearing 18 is disposed in the through portion of the discharge elbow 12. These bearings 16 and 18 consist of slide bearings, such as a cutless bearing and a ceramic bearing.

  The main shaft 15 penetrates the first bearing 16 and protrudes downward, and an impeller 19 for pumping water is fixed to the lower end of the main shaft 15. The main shaft 15 passes through a base 20 provided on the outer side of the second bearing 18 and the discharge elbow 12, and a motor (not shown) is connected to the upper end thereof. Then, by driving the prime mover, the impeller 19 is rotated through the main shaft 15 to pump up the water in the water absorption tank 1.

  As shown in FIGS. 2, 3, and 4, the bell mouth 21 connected to the lower end of the vane casing 14 includes a flange portion 22 for fixing to the vane casing 14 at the upper end. Bolt insertion holes 23 are provided in the flange portion 22 at a predetermined interval in the circumferential direction. In addition, the bell mouth 21 is provided with an outer trumpet portion 24 on the lower side of the upper portion gradually reduced in diameter downward from the flange portion 22. Inside the outer trumpet portion 24, an inner trumpet portion 26 integrally formed with a connecting rib 28 and an axial trumpet portion 30 integrally molded with a vortex preventing rib 31 are disposed.

  The outer trumpet portion 24 has a substantially conical cylindrical shape that gradually increases in diameter from the substantially central portion in the vertical direction of the bell mouth 21 toward the lower end. Specifically, the outer trumpet portion 24 includes an upper cylindrical portion 24a and a conical cylinder portion 24b that expands downward from the lower end of the cylindrical portion 24a. The outer trumpet 24 is located below the impeller 19, and the lower end opening 24 c is located above the bottom surface of the barrel casing 2, which is the bottom of the water absorption tank 1, at a predetermined interval. The outer trumpet portion 24 is provided with four connecting holes 25 at equal intervals (equal angles) in the circumferential direction for connecting the inner trumpet portion 26.

  The inner trumpet portion 26 is made of a resin such as FRP and has a substantially conical cylindrical shape that is disposed inside the outer trumpet portion 24 at a predetermined interval. Specifically, the inner trumpet portion 26 includes an upper cylindrical portion 26a and a conical cylinder portion 26b that expands downward from the lower end of the cylindrical portion 26a. In the inner trumpet portion 26, the lower end opening portion 26 c is positioned below the lower end opening portion 24 c of the outer trumpet portion 24. In addition, the inner trumpet portion 26 is formed such that the lower end outer peripheral portion having the largest diameter is smaller in diameter than the lower end outer peripheral portion of the outer trumpet portion 24. Further, the inner trumpet portion 26 is provided with four connection holes 27 at equal intervals in the circumferential direction for coupling the shaft center trumpet portion 30.

  On the outer surface portion of the inner trumpet portion 26, connecting ribs 28 for coupling to the outer trumpet portion 24 are provided at four equal intervals in the circumferential direction so as to extend radially outward. These connecting ribs 28 are provided so as to be phased in the circumferential direction at equal intervals (45 degrees) with respect to the connecting hole 27. The upper end surface of the connecting rib 28 is formed in an arc shape along the inner surface of the outer trumpet portion 24, and a bolt hole 29 coinciding with the connecting hole 25 is provided in the vicinity of the outer end portion. Further, the connecting rib 28 protrudes from the vicinity of the outer peripheral portion of the lower end of the inner trumpet portion 26. Thereby, each connection rib 28 is comprised so that it may protrude below from the lower end opening part 24c of the outer side trumpet part 24. FIG.

  The shaft center trumpet portion 30 is made of resin such as FRP, and is a shaft center portion disposed so as to extend along the axes of the outer trumpet portion 24 and the inner trumpet portion 26. The axial trumpet portion 30 has a substantially conical cylindrical shape projecting radially outward so that the diameter gradually increases toward the lower end. Specifically, the axial trumpet portion 30 includes an upper cylindrical portion 30a and a conical cylindrical portion 30b that expands downward from the lower end of the cylindrical portion 30a. The lower end opening 30c of the shaft center trumpet portion 30 is disposed below the lower end opening 26c of the inner trumpet portion 26 and is disposed above the bottom surface of the barrel casing 2 at a predetermined interval. In addition, the lower end opening 30 c of the axial trumpet portion 30 is formed to have a smaller diameter than the diameter of the lower end opening 26 c of the inner trumpet portion 26.

  An eddy current preventing rib 31 for suppressing the generation of underwater vortex and connecting to the inner trumpet portion 26 is provided on the outer surface portion of the shaft center trumpet portion 30. The eddy current preventing ribs 31 are provided so as to extend radially outward at four locations at equal intervals in the circumferential direction. The upper end surface of the vortex preventing rib 31 is formed in an arc shape along the inner surface of the inner trumpet portion 26, and a bolt hole 32 that coincides with the connection hole 27 is provided in the vicinity of the outer end portion. Further, the eddy current preventing rib 31 protrudes outward from the outer peripheral portion of the lower end of the axial center trumpet portion 30. Accordingly, each vortex preventing rib 31 is configured to protrude downward from the lower end opening 26 c of the inner trumpet portion 26. Further, the upper end of the eddy current preventing rib 31 is configured to be located in the outer trumpet portion 24.

  In the present embodiment, the outer trumpet portion 24 sets the upper end inner diameter Do2 to 0.575 Do1 with the lower end outer diameter Do1 as a reference. Further, the inner trumpet portion 26 has a lower end outer diameter Di1 set to 0.950 Do1 and an upper end outer diameter Di2 set to 0.475 Do1. Furthermore, the shaft center wrapper 30 has a lower end outer diameter Da1 set to 0.500 Do1 and an upper end outer diameter Da2 set to 0.100 Do1. On the other hand, the protrusion dimension L1 from the lower end of the outer trumpet portion 24 to the lower end of the vortex preventing rib 31 of the shaft center trumpet portion 30 is set to 0.440 Do1, and the vortex preventing rib 31 of the shaft center trumpet portion 30 is set from the lower end of the inner trumpet portion 26. The projecting dimension L2 to the lower end of is set to 0.310 Do1 or more. Here, if the protrusion dimension L2 of the vortex preventing rib 31 is less than 0.310 Do1, the vortex generation flow rate decreases, that is, the underwater vortex is generated at a low flow rate. As a result, the pump efficiency is reduced.

  When the inner trumpet portion 26 and the shaft center trumpet portion 30 are assembled to the pump casing 10 having the outer trumpet portion 24, the shaft center trumpet portion 30 is first assembled to the inner trumpet portion 26. At this time, the axial trumpet portion 30 is disposed on the inner side from the lower end opening 26c of the inner trumpet portion 26, the bolt hole 32 of the vortex preventing rib 31 is aligned with the connecting hole 27, and the bolt hole 32 is tightened and connected by a bolt. Thereafter, the inner trumpet portion 26 connected to the axial trumpet portion 30 is assembled to the outer trumpet portion 24. At this time, the inner trumpet portion 26 is arranged on the inner side from the lower end opening 24c of the outer trumpet portion 24, the bolt holes of the connecting ribs 28 are aligned with the connecting holes 25, and the bolts are tightened and connected by bolts.

  And the vertical shaft which assembled these has the eddy current prevention rib 31 which protrudes radially from the inner side of the outer trumpet part 24, and protrudes downward from the lower end opening part 24c. Therefore, instead of the + -shaped baffle or cone that is constructed in the water absorption tank 1, the flow of the pumped water is rectified to reliably suppress the generation of underwater vortices. And since the eddy current prevention rib 31 is a very simple structure compared with the + character baffle and cone which require a large-scale construction, cost can be reduced significantly.

  Moreover, since the eddy current preventing rib 31 is disposed inside the outer trumpet portion 24 at the lower end of the water pumping pipe 11, it can be easily positioned along the axis of the water pumping pipe 11. Therefore, compared with the case where a + -shaped baffle or cone is constructed in the water absorption tank 1, workability regarding installation accuracy can be greatly improved. Moreover, the eddy current preventing rib 31 of the present embodiment is not limited to the vertical pump installed in the newly constructed machine station, and even if the vertical pump is installed in the existing machine factory, it is only necessary to provide the connection hole 25 in the outer trumpet portion 24 of the bell mouth 21. It can be reliably arranged.

  Further, in the vertical shaft pump, the flow path in the outer trumpet portion 24 is partitioned by the shaft center trumpet portion 30 and the inner trumpet portion 26. Then, air flows into the inside through the partitioned flow path during the air lock operation, but the flow path is closed with water in the water level region before and after the transition to the air lock operation, so that the inflow of air can be prevented. As a result, it is possible to realize a preliminary standby operation in which the generation of air suction vortices is reliably suppressed. Further, the suction performance can be improved by a synergistic effect with the eddy current preventing rib 31. In other words, the triple trumpet vertical shaft pump according to the first embodiment prevents radial water flow in the outer trumpet portion 24 by the plurality of trumpet portions 26 and 30 in the outer trumpet portion 24 and extends radially. Since the water flow in the circumferential direction can be prevented by the ribs 28 and 31 protruding downward, it is possible to greatly prevent the generation of underwater vortices.

(Second Embodiment)
5 to 7 show the suction part structure of the vertical shaft pump according to the second embodiment. In the second embodiment, only the axial trumpet portion 30 having the eddy current preventing ribs 31 is disposed inside the outer trumpet portion 24 of the bell mouth 21 without disposing the inner trumpet portion 26. Thus, this is different from the first embodiment. The vortex preventing rib 31 of the axial trumpet portion 30 of the second embodiment has an upper end surface formed in an arc shape along the inner surface of the outer trumpet portion 24, and a bolt hole that coincides with the connecting hole 25 in the vicinity of the outer end portion. 32 is provided.

  In the second embodiment, the upper end inner diameter Do2 is set to 0.575 Do1 with the lower end outer diameter Do1 of the outer trumpet portion 24 as a reference. Further, the shaft center wrapper 30 has a lower end outer diameter Da1 set to 0.500 Do1 and an upper end outer diameter Da2 set to 0.100 Do1. On the other hand, the protrusion dimension L1 from the lower end of the outer trumpet portion 24 to the lower end of the vortex preventing rib 31 of the shaft center trumpet portion 30 is set to 0.310 Do1. That is, in the present invention, the eddy current preventing rib 31 is set so that the projecting dimensions L2 and L1 from the lower ends of the trumpet portions 24 and 26 located at the lower ends are 0.310 Do1 or more. The vertical shaft pump of the second embodiment configured as described above has substantially the same operation and effect although the vortex generation flow rate is lower than that of the first embodiment.

( First Reference Example )
8 to 10 show the suction part structure of the vertical shaft pump of the first reference example . In the first reference example , the inner trumpet portion 26 is not provided as in the second embodiment, and the cylindrical cylindrical shaft portion 33 is arranged in place of the conical cylindrical axial trumpet portion 30. This is different from the second embodiment. The vertical shaft pump of the first reference example configured as described above can obtain substantially the same operation and effect although the vortex generation flow rate is reduced as compared with the second embodiment.

( Second reference example )
11 to 13 show a suction part structure of a vertical shaft pump according to a second reference example . In the second reference example , similarly to the second embodiment and the first reference example , the inner trumpet portion 26 is not disposed, and the axial trumpet portion 30 is not formed, and only the vortex preventing rib 31 is disposed. It is different in that it is configured to be installed. The vertical shaft pump of the second reference example configured as described above cannot reliably prevent the generation of the air suction vortex as compared with each embodiment, but can reliably prevent the generation of the underwater vortex.

( Third embodiment )
FIG. 14 shows a vertical shaft pump according to the third embodiment . This vertical shaft pump is installed by fixing the lower end of the discharge elbow 12 to the installation floor 4 provided above the water absorption tank 1 and hanging the lower part from the pumping pipe 11. In the pump casing 10 of the vertical shaft pump, as in the first embodiment, an inner trumpet portion 26 having a connecting rib 28 at the lower end and a shaft center trumpet portion 30 having a swirl prevention rib 31 are disposed.

In addition, the vertical pump of the third embodiment is not used for draining water in the water absorption tank 1 such as when normal operation is not performed over a long period of time, but during the management operation that is operated for the purpose of maintaining performance or the like. A cleaning mechanism 34 is mounted for cleaning. The cleaning mechanism 34 includes horizontal pipes 35A and 35B connected to symmetrical positions of the discharge elbow 12. Straight pipe vertical pipes 36A and 36B are connected to the horizontal pipes 35A and 35B. These vertical pipes 36 </ b> A and 36 </ b> B are arranged on the outside of the pump casing 10 at intervals, and extend downward in the vertical direction in parallel with the main shaft 15. On the vertical pipes 36A and 36B, on-off valves 37A and 37B are interposed in the vicinity of the horizontal pipes 35A and 35B. An annular pipe 38 is connected to the lower ends of the vertical pipes 36 </ b> A and 36 </ b> B so as to surround the pump casing 10 with a space therebetween. The annular pipe 38 is provided with a plurality of nozzles 39 at equal intervals in the circumferential direction. These nozzles 39 are all disposed downward toward the bottom of the water absorption tank 1. The arrangement position of the nozzle 39 is not limited to the outside of the pump casing 10, and can be changed as desired, such as the outside of the outer trumpet 24, the outer side of the shaft trumpet 30, or the lower side.

During normal operation of the vertical pump according to the third embodiment , the same operations and effects as those of the first embodiment can be obtained. In addition, during the management operation, the vertical shaft pump is activated to open the on-off valves 37A and 37B. Thereby, the water in the water absorption tank 1 sucked from the lower end openings 24c, 26c, 30c of the trumpet portions 24, 26, 30 of the bell mouth 21 passes through the horizontal pipes 35A, 35B and the vertical pipes 36A, 36B from the pump casing 10. Then, the pressure is fed to the annular pipe 38. The water pumped to the annular pipe 38 is ejected from the nozzle 39 into the water absorption tank 1, and is deposited on the bottom of the water absorption tank 1. To do. Then, the normal operation of the vertical shaft pump is performed after the foreign matter is sufficiently floated, so that the foreign matter can be pumped downstream together with the water, and the inside of the water absorption tank 1 can be effectively cleaned.

  In order to confirm the effect of the present invention, the inventors of the present application conducted an experiment using a barrel casing 2 in which an underwater vortex is easily generated. The suction part structure of the vertical shaft used in this experiment is shown in FIG. The conventional product 1 is a general vertical shaft pump having only the outer trumpet portion 24. The conventional product 2 is a vertical shaft pump in which a rib in a + shape in plan view is provided in the outer trumpet portion 24 so as not to protrude from the lower end opening 24c. The conventional product 3 is a vertical shaft pump similar to Patent Document 2 in which an inner trumpet portion 26 having a connecting rib 28 is disposed inside the outer trumpet portion 24. The product 1 of the present invention is a vertical shaft pump according to the first embodiment in which an inner trumpet portion 26 having a connecting rib 28 and an axial trumpet portion 30 having a vortex preventing rib 31 are disposed inside the outer trumpet portion 24. The product 2 of the present invention is the vertical shaft pump according to the second embodiment in which only the shaft center trumpet portion 30 having the vortex preventing ribs 31 is disposed inside the outer trumpet portion 24.

These vertical shaft pumps are installed in a barrel casing 2 not provided with a + -shaped baffle or cone and operated at a specific speed Ns of 700, and the vortex generation flow rate Q / Q _BEP (%), efficiency (%), suction ratio The speed S was measured. The vertical pump disposed in the barrel casing 2 is generally characterized by a high internal flow rate and easy generation of underwater vortices.

As a result of visual measurement of the vortex generation flow rate Q / Q _BEP of each vertical shaft pump through the see-through window provided at the bottom of the barrel casing 2, the conventional product 1 is 43%, the conventional product 2 is 61%, the conventional product 3 is 74%, The product 1 of the present invention was 141% and the product 2 of the present invention was 128%. From this result, it was confirmed that the vertical pumps of the products 1 and 2 of the present invention can greatly suppress the generation of submerged vortex compared to the vertical pumps of the conventional products 1 to 3. In particular, the vertical pump of the conventional product 3 (Patent Document 2) in which only the inner trumpet portion 26 is disposed inside the outer trumpet portion 24, and the present invention in which only the shaft center trumpet portion 30 is disposed inside the outer trumpet portion 24. When compared with the vertical pump of the product 2 (second embodiment), the flow rate of the vortex generating pump can be increased by 50% despite the similar double trumpet type. This can be said that the eddy current preventing rib 31 protruding greatly from the outer trumpet portion 24 has a great effect.

  Moreover, the efficiency regarding the drainage of each vertical shaft pump is η% for the conventional product 1, η-0.3% for the conventional product 2, η-0.4% for the conventional product 3, and η-0.5 for the product 1 of the present invention. %, Invention product 2 was η-0.4%. That is, the efficiency of the conventional product 1 is the best and the product 1 of the present invention is the worst. This is considered because the flow path in the outer trumpet portion 24 is blocked by the inner trumpet portion 26, the connecting rib 28, the axial center trumpet portion 30, and the eddy current preventing rib 31. However, the difference is 0.4%, which is extremely small. Therefore, it can be said that this invention products 1 and 2 can suppress generation | occurrence | production of an underwater vortex significantly, without almost reducing drainage efficiency.

Further, the suction specific speed Smin is the smallest in the excessive flow rate region (140%) Q _BEP of the conventional product 2. Therefore, when compared with the ratio of the suction specific speed Smin of the conventional product 2, the suction specific speed ratio S / Smin by each vertical shaft pump is 1.383 for the highest efficiency (100%) Q _BEP. 2 was 1.482, Conventional product 3 was 1.544, Invention product 1 was 1.500, and Invention product 2 was 1.498. In addition, in the excessive flow rate (140%) Q _BEP , the conventional product 1 is 1.046, the conventional product 2 is 1.000, the conventional product 3 is 1.203, the present product 1 is 1.123, and the present product 2 is 1.154. It was. From these results, the products 1 and 2 of the present invention can improve the suction specific speed ratio S / Smin as compared with the conventional products 1 and 2. However, the suction specific speed ratio S / Smin is slightly inferior to the conventional product 3 with improved suction performance.

  From the above results, it can be said that the vertical shaft pumps of the products 1 and 2 of the present invention can significantly suppress the generation of the underwater vortex without substantially reducing the drainage efficiency as compared with the vertical pump of the conventional product. And since the underwater vortex is directly linked to the vibration of the pump, the vertical shaft pump of the present invention capable of greatly suppressing the generation thereof can reduce the vibration during operation. Further, as is apparent from the experimental results of the conventional product 2, the generation of the underwater vortex cannot be significantly suppressed only by providing the + -shaped rib only in the outer trumpet portion 24. Therefore, it is necessary to provide the vortex preventing rib 31 so as to project radially outward and project downward from the lower end opening 24c inside the outer trumpet portion 24.

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

For example, it is good also as a structure which arrange | positions the axial center cylindrical part 33 shown in a 1st reference example instead of the axial center wrapper part 30 of the triple wrapper type | formula vertical shaft pump shown in 1st Embodiment. Further, in each of the embodiments , four eddy current preventing ribs 31 are provided so as to form a + shape in plan view. However, the number can be changed as desired as long as it is three or more.

In the first embodiment, the inner trumpet portion 26 and the shaft center trumpet portion 30 are separately formed of a resin such as FRP, but may be integrally formed. The forming material is not limited to resin, and may be formed of cast iron. Of course, the axial trumpet portion 30 having the eddy current preventing rib 31 of the second embodiment, the axial cylindrical portion 33 having the eddy current preventing rib 31 of the first reference example , and the eddy current preventing rib 31 of the second reference example are also formed of cast iron. May be.

DESCRIPTION OF SYMBOLS 1 ... Water absorption tank 2 ... Barrel casing 3 ... Inlet 10 ... Pump casing 11 ... Pumping pipe 12 ... Discharge elbow 14 ... Vane casing 15 ... Main shaft 19 ... Impeller 21 ... Bell mouth 24 ... Outer trumpet part 24c ... Lower end opening part 26 ... Inner trumpet part 26c ... Lower end opening part 28 ... Connecting rib 30 ... Axial trumpet part (axial center part)
30c ... Lower end opening 31 ... Eddy current preventing rib 33 ... Axial cylindrical part (axial center part)

Claims (4)

In a vertical shaft pump having a pumping pipe and a main shaft extending in the pumping pipe and having an impeller fixed to the lower end side,
An outer trumpet that is provided on the lower side of the impeller on the lower end side of the pumping pipe and expands toward the lower end;
A substantially conical cylinder-shaped center trumpet portion that is provided inside the outer trumpet portion, extends along the axis of the outer trumpet portion, and projects radially outward so as to gradually increase in diameter toward the lower end; ,
A vertical shaft pump comprising: three or more vortex-preventing ribs projecting radially outward from an outer surface of the axial trumpet portion and projecting downward from a lower end opening of the outer trumpet portion. An inner trumpet portion is provided between the outer trumpet portion and the axial trumpet portion. The inner trumpet portion extends downward from the outer trumpet portion at a predetermined interval and the lower end opening portion is located below the lower end opening portion of the outer trumpet portion. Set up
The outer and inner trumpet portions are connected by three or more connecting ribs projecting radially outward from the inner trumpet portion, and the eddy current preventing ribs are connected to the inner side of the inner trumpet portion. The vertical shaft pump according to claim 1 . The vertical shaft pump according to claim 2, wherein the connecting rib is protruded downward from a lower end opening of the outer trumpet. The vertical shaft pump according to claim 1, wherein the vortex preventing rib is connected to an inner side of the outer trumpet portion.

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