JP2010121480A - Preceding standby operation pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a preceding standby operation pump by which a pumping operation can be securely shut off on an occasion when shut-off of pumping is wanted, and occurrence of whirlpools and vibration can be suppressed. <P>SOLUTION: In this pump, a first air-intake 21b, a second air-intake 22b, and steam-mixing and pumping shut-off air pipes 21, 22 provided. Under conditions that fed-water level WL is not higher than the lowest water-level LWL, the first air-intake 21b serves to decrease a displacement by pumping up water, while introducing air into a casing 3 below an impeller 11. By the second air-intake 22b, when the fed-water level WL has reached a pumping shut-off level SWL lower than the lowest water-level LWL, air is introduced into the casing 3 lower than the impeller 11 to shut off the pumping. By the air-pipes 21, 22, the two kinds of air intakes 21b, 22b are allowed to communicate with the inside of a casing 3. The position of the opening 26 in the casing 3 for the pumping shut-off air pipe 22 is set upper than the opening 25 in the casing 3 for the air pipe 21 for the steam mixing so that efficiency of air-introduction (intake) in the casing 3 at the pumping shut-off time is improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a preceding standby operation pump installed in a suction water tank of a drainage station.

Conventionally, a casing having a suction port opened in the suction water tank at the lower end, an impeller disposed inside the casing, and pumping water while introducing air into the casing below the impeller reduces the amount of drainage. There are known vertical shaft pumps having a gas / water mixing air supply port, that is, a prior standby operation pump (see Patent Documents 1 and 2, etc.).
JP 2004-239215 A JP 2006-291900 A

  However, it has been difficult to introduce an appropriate amount of air using only the air / water mixing inlet. That is, when an air pipe capable of introducing a sufficient amount of air for shutting off pumping at a predetermined water level is installed at the time of air-water mixing operation, the air-water mixing operation introduces an excessive amount of air and increases vibrations. There is a possibility of blocking pumping above the water level. However, with an air pipe that reduces the amount of air that can be introduced, even if the water level in the suction tank drops to the level at which it is desired to block the pumping, the pumping may not be blocked. In order to cut off the pumping, the vibration sometimes increased. When the vibration level of the pump increases, it is necessary to increase the strength of the pump accordingly, which may increase the weight of the pump. In addition, when the pump weight increases, it may be necessary to increase the floor strength of the drainage station that covers the upper surface of the suction water tank and suspends the pump.

  The preceding standby operation pump of the present invention includes a casing having a suction port opened in the suction water tank at a lower end, an impeller disposed inside the casing, and a state in which the water level of the suction water tank is equal to or lower than a first predetermined water level. A first air supply port for reducing the amount of drainage by pumping water while introducing air into the casing below the impeller, and a second predetermined level in which the water level of the suction water tank is lower than the first predetermined level When the water level is reached, a second air supply port for blocking pumping is provided by introducing air into the casing below the impeller, and the two types of air supply ports and the inside of the casing are provided. An air pipe having an air pipe for communication, and an opening position in the casing of the air pipe for communicating between the second air supply port and the inside of the casing is an air tube case for connecting the first air supply port and the inside of the casing. In the casing below the impeller when the water level of the suction water tank is lower than the first predetermined water level, the air pipe from the first air supply port and its The air-water mixing operation is performed by reducing the amount of drainage by pumping water while introducing air through the opening in the casing of the air pipe, and the water level of the suction water tank is lower than the first predetermined water level by the air-water mixing operation. When a predetermined water level is reached, pumping is shut off by introducing air from the second air supply port through the air pipe and the opening in the casing of the air pipe into the casing below the impeller to switch to pumping shut-off operation. Is.

  In the preceding standby operation pump according to the present invention, the opening position in the casing of the air pipe that communicates the second air supply port and the inside of the casing is defined as the air that communicates the first air supply port and the inside of the casing. It is desirable to shift in the circumferential direction of the casing with respect to the opening position in the casing of the tube.

  According to the preceding standby operation pump of the present invention, a casing having a suction port opened in the suction water tank at the lower end, an impeller disposed in the casing, and a state in which the water level of the suction water tank is equal to or lower than a first predetermined water level A first air supply port for lowering the amount of drainage by pumping water while introducing air into the casing below the impeller, and a second water level of the suction water tank lower than the first predetermined water level When a predetermined water level is reached, a second air supply port is provided for shutting off pumping by introducing air into the casing below the impeller, and the two types of air supply ports and the casing interior Since an air pipe that communicates with the pump is provided, an air amount sufficient for shutting off the pumping can be introduced only at the time of shutting off the pumping, and optimization of the amount of air introduced during the air-water mixing operation can be easily achieved. Uninari, in steam-water mixing air inlet only it is possible to suppress the occurrence and vibration of the vortex than introducing air. As a result, there is no need to increase the strength of the pump, the weight of the pump can be reduced, and the floor strength of the drainage station may not need to be increased.

  In addition, the amount of air introduced at the time of the air-water mixing operation and the amount of air introduced at the time of shutting off the pumping can be easily set, and the above-described effects can be easily realized.

  Furthermore, the opening position in the casing of the air pipe that connects the second air supply port and the inside of the casing is above the opening position in the casing of the air pipe that connects the first air supply port and the inside of the casing. In other words, because it is close to the impeller, air can be introduced (intake) efficiently and effectively into the casing below the impeller through the air pipe from the second air supply port when pumping is shut off. When the water absorption level is lowered (during the air-water mixing operation), the air pipe can accurately and stably shut off the pumping water and communicate the first air supply port with the inside of the casing. The opening position in the casing can be made lower, and pumping can be shut off at a lower water level.

  In the preceding standby operation pump of the present invention, the opening position in the casing of the air pipe that connects the second air supply port and the inside of the casing is set in the casing of the air pipe that connects the first air supply port and the inside of the casing. The position where the mixing ratio of water and air is locally increased in the casing below the impeller, i.e., the first air inlet and the casing inside is shifted by shifting the casing in the circumferential direction of the casing. Air is introduced (intake) more efficiently and effectively into the casing below the impeller through the air pipe from the second air supply port when the pumping is shut off, avoiding the opening position in the casing of the air pipe to be communicated Will be able to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a preceding standby operation pump showing a first embodiment, and FIG. 2 is a transverse sectional view of an air introduction portion in the pump.

  1 and 2, the preceding standby operation pump 1 is a vertical shaft pump that drains water such as rainwater flowing into the suction water tank 2 of the drainage station to the downstream side.

  The casing 3 extending in the vertical direction includes a straight tubular pumping pipe 4, a pump casing 5 connected to the lower end of the pumping pipe 4, a suction pipe (suction bell) 6 connected to the lower end of the pump casing 5, and a pumping pipe. 4 and a discharge elbow 7 curved in the horizontal direction from the vertical direction, and having a suction port 8 at the lower end of the suction pipe 6 (lower end of the casing 3). 3 is connected to a discharge pipe (drainage pipe) 10.

  The impeller 11 is disposed in the pump casing 5 via the main shaft 13, and a plurality of guide blades 12 are disposed in the pump casing 5 above (downstream side) the impeller 11.

  The main shaft 13 extending in the vertical direction is supported at the center of the casing 3 via a plurality of bearings 14, 15, and 16, and the impeller 11 is attached to the vicinity of the lower end of the main shaft 13 so as to be integrally rotatable. The upper end side of the main shaft 13 passes through the discharge elbow 7 in a rotatable and watertight manner, protrudes outside the casing 3, and is connected to a rotation drive mechanism 17 including a drive source such as an engine and an electric motor and a speed reduction mechanism. .

  The lower end bearing 16 that supports the lower end of the main shaft 13 is fixed to the inner surface of the suction pipe 6 on the outer side of the impeller 11 just below (upstream side) via four (a plurality of) support plates 16a. The support plate 16 a also serves as a guide plate that divides a passage between the outer surface of the opposed lower end bearing 16 and the inner surface of the suction pipe 6 at substantially equal intervals and guides water to flow in the axial direction of the main shaft 13. The outer surfaces of the remaining bearings 14 and 15 are also fixed to the inner surface of the pumped-up pipe 4 by similar support plates 14a and 15a.

  A flange 18 for installation is provided at the upper part of the casing 3, and a hole 20 through which the pump 1 below the flange 18 can be inserted is provided in the concrete floor 19 of the drainage pump station covering the upper surface of the suction water tank 2. It has been. The pump 1 is installed on the floor 19 via the flange 18 with the lower side of the flange 18 suspended in the suction water tank 2 through the hole 20.

  And in the state where the water level WL of the suction water tank 2 is below the minimum water level LWL which will be described later, the preceding standby operation pump 1 reduces the amount of drainage by pumping water while introducing air into the casing 3 below the impeller 11. When the water level of the suction water tank 2 is lower than the minimum water level LWL and becomes a pumping cutoff water level SWL, which will be described later, air is introduced into the casing 3 below the impeller 11. The two air pipes 21 and 22 (an example of the air pipe) for shutting off the pumped water are provided, and the air pipes 21 and 22 are provided with opening and closing means 23 and 24, respectively. ing.

  On the pipe wall of the suction pipe 6 (an example of the casing) below the impeller 11, a first opening (air inlet for air / water mixing; casing) that penetrates the inner / outer surface serving as an attachment portion of the air / water mixing air pipe 21. And a second opening (an intake port for pumping water; an opening in the casing) 26 serving as a mounting portion for the pumping-off air pipe 22.

  Two (plural) first openings 25 are arranged at equal intervals at the same height position. One second opening 26 is disposed below the lower end of the impeller 11 and above the first opening 25 (preferably disposed at a position as close as possible to the impeller 11). The first opening 25 is arranged so as to be displaced in the circumferential direction so as not to overlap any of the first openings 25 when viewed from the axial direction of the main shaft 13. In addition, the circumferential position of the second opening 26 is shifted in the circumferential direction with respect to the first opening 25 so as to be positioned approximately at the center between the two adjacent first openings 25. . Therefore, in this embodiment, two (a plurality of) air-water mixing air pipes 21 and one pumping-off air pipe 22 are provided.

  The air / water mixing air pipe 21 is bent into an inverted U shape having a folded portion at the upper end, and the folded portion at the upper end is disposed above the floor 19. Then, both end portions are extended into the suction water tank 2 through the holes 20, and one end 21 a is connected to the first opening 25. In addition, since the folding part is set at a position higher than the suction lift by the maximum negative pressure generated in the first opening 25 due to the pumping of water, water is not sucked up beyond the folding part, so that dust etc. Can reduce the possibility of clogging the folded portion.

  Further, the tip 21b (the other end; an example of the first air supply port) of the air / water mixing air pipe 21 has a water level (hereinafter referred to as “water absorption level”) LW of the suction water tank 2 as a minimum water level LWL (described later). It is provided so as to be submerged when rising to an example of the first predetermined water level. Therefore, the tip 21b of the air / water mixing air pipe 21 is opened in the atmosphere until the water absorption level LW rises to the lowest water level LWL, and the air / water mixing air pipe 21 is held open. When the water level rises to the lowest water level LWL, it is blocked by the water in the suction water tank 2, and when the water absorption level LW is equal to or higher than the lowest water level LWL, the air / water mixing air pipe 21 is kept closed. That is, the opening / closing means 23 of the air / water mixing air pipe 21 is constituted by the tip 21 b of the air / water mixing air pipe 21.

  Similarly to the air / water mixing air pipe 21, the pumping-off air pipe 22 is bent into an inverted U shape having a folded portion at the upper end, and the folded portion at the upper end is disposed above the floor 19. . Both end portions are extended into the suction water tank 2 through the holes 20, and one end 22 a is connected to the second opening 26. In addition, since the folded portion is set at a position higher than the suction lift by the maximum negative pressure generated in the second opening 26 due to the pumping of water, water is not sucked up beyond the folded portion, so that the dust etc. Can reduce the possibility of clogging the folded portion.

  Further, when the tip 22b (the other end; one example of the second air supply port) of the pumping-off air pipe 22 rises to the pumping cutoff water level SWL (an example of the second predetermined water level) that the water absorption level LW will be described later on. To be submerged in water. Therefore, the tip 22b of the pumping-off air pipe 22 is opened in the atmosphere until the water absorption level LW rises to the pumping-off water level SWL, and the pumping-off air pipe 22 is held open. When the water level rises to the pumping cutoff water level SWL, it is blocked by water in the suction water tank 2 and when the water absorption level LW is equal to or higher than the pumping cutoff water level SWL, the pumping cutoff air pipe 22 is kept closed. That is, the opening / closing means 24 of the pumping-off air pipe 22 is constituted by the tip 22 b of the pumping-off air pipe 22.

  In the present embodiment, the two air / water mixing air pipes 21 and the pumped water blocking air pipe 22 are divided into the amount of air introduced from the two air / water mixing air pipes 21 and one pumped water blocking air pipe 22. The thing of the pipe diameter that the air quantity to introduce | transduces becomes substantially the same is used. Since there is one pumping cutoff air pipe 22 for the two air / water mixing air pipes 21, the diameter of each air / water mixing air pipe 21 is approximately 1 / of the pipe diameter of the pumping / water blocking air pipe 22. √2.

  On the inner surface of the suction pipe 6, a rib 27 is provided as a pressure reducing means for reducing the fluid pressure in the vicinity of the second opening 26 to block the flow in the impeller rotational direction. Here, as shown in FIG. 2, the four support plates 16 a of the lower end bearing 16 have an outer end portion of one of the support plates 16 a as viewed from the axial direction of the main shaft 13. It is constructed between the outer surface of the opposed lower end bearing 16 and the inner surface of the suction pipe 6 so as to be connected to the inner surface of the suction pipe 6 in the vicinity of the upstream side in the impeller rotation direction (arrow A direction). Further, the four support plates 16a of the lower end bearing 16 have a lower end located above the first opening 25, an upper end located below the lower end of the impeller 11, and the first opening 25 is not included. The second opening 26 extends between the outer surface of the opposite lower end bearing 16 and the inner surface of the suction pipe 6 in a height range including the second opening 26. Therefore, the outer end portion of the support plate 16a connected to the inner surface of the suction pipe 6 in the vicinity of the upstream side of the second opening 26 in the impeller rotation direction is in the impeller rotation direction immediately before passing through the second opening 26. Block the flow. That is, the pressure reducing means 27 is constituted by an outer end portion of a support plate (rib) 16 a connected to the inner surface of the suction pipe 6 in the vicinity of the upstream side of the second opening 26 in the impeller rotation direction. In addition, the rib as a pressure reduction means is not limited to the above-mentioned thing, The form etc. which protruded in the cantilever state to the inner surface of the casing 3 may be sufficient.

  The four support plates 16a of the lower end bearing 16 have a suction pipe in which the outer end portion of one support plate 16a is near the upstream side in the impeller rotation direction of the second opening 26 when viewed from the axial direction of the main shaft 13. 6, the outer end portions of the two support plates 16 a adjacent to the one support plate 16 a are viewed from the axial direction of the main shaft 13, and the impeller rotation direction of the first opening 25. It is connected to the inner surface of the suction pipe 6 in the vicinity of the upstream side. That is, the circumferential positional relationship between the openings 25 and 26 provided in the suction pipe 6 and the outer end portion of the support plate 16a of the lower end bearing 16 is the impeller of the openings 25 and 26 when viewed from the axial direction of the main shaft 13. The outer end portion of the support plate 16a is positioned near the upstream side in the rotation direction.

  A vortex generation preventing plate 28 is provided on the outer surface of the suction pipe 6 between the suction port 8 and the first opening 25. The vortex generation preventing plate 28 is formed of a horizontal plate that is in surface contact with the water surface when the water absorption level LW is lowered to the vicinity of the pumping cutoff water level SWL. The horizontal plate is larger than the suction port 8 and smaller than the hole 20 of the floor 19. The vortex generation preventing plate 28 may be composed of a plurality of vertical plates provided radially on the outer surface of the suction pipe 6 below the first opening 25. A horizontal plate or vertical plate larger than the hole 20 may be used.

  Next, the relationship between the structure in the height direction of the preceding standby operation pump 1 and the water absorption level LW will be described with reference to FIG.

  First, the maximum water level HWL peculiar to the suction water tank 2 is set to the suction water tank 2 as the allowable water level.

  Below the highest water level HWL, the lowest water level LWL (the first predetermined water level), which is unique to the pump 1 (the pump here is a vertical shaft pump that does not include the air pipes 21, 22 and the vortex generation prevention plate 28). One example) is set. Below that, the minimum water level LWL corresponds to the water absorption level WL in which vortex, that is, air is sucked from the suction port 8 and vibration and noise are generated, and the operation cannot be continued. The preceding standby operation pump 1 is operated by pumping water while reducing the amount of drainage while introducing air into the casing 3 below the impeller 11 through the air / water mixing air pipe 21, so that the water absorption is lower than the lowest water level LWL. Since the start at the position WL and continuous operation are possible, the tip 21b of the air / water mixing air pipe 21 is at a position that is open to the atmosphere at least when the water absorption level WL falls below the minimum water level LWL. It should be provided. In the present embodiment, the air / water mixing air pipe 21 is also provided with an opening / closing means 23, and the opening / closing means 23 is constituted by a tip 21 b of the air / water mixing air pipe 21. Therefore, as described above, the tip 21b (an example of the first air supply port) of the air / water mixing air pipe 21 is provided so as to be submerged when the water absorption level LW rises to the lowest water level LWL. Until the LW rises to the lowest water level LWL, it is opened in the atmosphere and the air-water mixing air pipe 21 is kept open, and when the water absorption level LW rises to the lowest water level LWL, the water in the suction water tank 2 When the water absorption level LW is equal to or higher than the lowest water level LWL, the air / water mixing air pipe 21 is held closed.

  The impeller 11 is disposed below the lowest water level LWL. If it is the minimum water level LWL, it arrange | positions so that the whole impeller 11 or at least the lower end part of the impeller 11 may be submerged.

  A pumping start water level RWL is set below the lowest water level LWL. The pumping start water level RWL corresponds to the water absorption level WL at the lower end of the impeller 11, and the water absorption level WL that starts pumping first after the pump 1 is started (when there is no water in the casing 3 above the impeller 11). It is.

  A second opening 26 and pressure reducing means 27 (support plate 16a of the lower end bearing 16) are disposed below the pumping start water level RWL, and a first opening 25 is disposed below the second opening 26 and the pressure reducing means 27.

  A re-pumping start water level CWL is set below the pumping start water level RWL. The re-pumping start water level CWL corresponds to the water absorption level WL at the upper end of the first opening 25, and after water is drained and the pumping shut-off operation (standby operation) is performed (there is water in the casing 3 above the impeller 11). In this case, the water absorption level WL can be re-pumped.

  Below the re-pumping start water level CWL, a pumping cutoff water level SWL (an example of a second predetermined water level) is set. The pumping shut-off water level SWL opens the pumping shut-off air pipe 22 by the opening / closing means 24 when the water absorption level WL is lowered from the first opening 25 in the air-water mixing operation, and the impeller 11 passes through the pumping shut-off air pipe 22. It is the water absorption level WL which introduce | transduces air in the lower casing 3 and interrupts pumping, and switches to pumping off operation. Therefore, as described above, the tip 22b (an example of the second air supply port) of the pumping-off air pipe 22 is provided so as to be submerged when the water absorption level LW rises to the pumping-off water level SWL. Until the LW rises to the pumping shut-off water level SWL, it is opened in the atmosphere and the pumping shut-off air pipe 22 is kept open, and when the water sucking level LW rises to the pumping shut-off water level SWL, When the water absorption level LW is equal to or higher than the pumping cutoff water level SWL, the pumping cutoff air pipe 22 is held in a closed state.

  When the pump 1 is operated at a low water level near the pumping cutoff water level SWL, vortices are likely to be generated, and vortex, that is, air is easily sucked. It is arranged on the outer surface of the suction pipe 6 between the first opening 25.

  A suction port 8 is disposed below the pumping cutoff water level SWL. For example, the suction port 8 is opened at a height position having a dimension substantially equal to the pipe diameter (inner diameter) of the pumped water pipe 4 that is the body portion of the casing 3 with respect to the bottom surface 2 a of the suction water tank 2.

  Next, the transition of the operation state (drainage state) of the preceding standby operation pump 1 will be described with reference to FIG.

  Since it is the preceding standby operation pump 1, it starts before the water absorption level WL rises to the lowest water level LWL (an example of the first predetermined water level) based on rainfall information or the like. In the present embodiment, the water absorption level WL rises to the pumping cutoff water level SWL (an example of the second predetermined water level) by water such as rainwater to the suction water tank 2, and the pumping cutoff air pipe 22 is closed by the opening / closing means 24. The pump 1 is started.

  Until the water absorption level WL rises to the pumping start water level RWL after the pump 1 is started, the impeller 11 is idling in the air.

  When the water absorption level WL rises and reaches the pumping start water level RWL, the impeller 11 starts pumping and starts draining. At this time, the pressure in the first opening 25 part is the water on the inflow side of the impeller 11. It is lowered by the flow of air and becomes lower than atmospheric pressure. And since the front-end | tip 21b (an example of a 1st air supply opening) of the air pipe 21 for air-water mixing is hold | maintained by the opening-and-closing means 23, from the 1st opening 25 through the air pipe 21 for air-water mixing. Since air is sucked in and the impeller 11 pumps up water while sucking in air, drainage starts in a state where the drainage amount is lower than the rated drainage amount. That is, the air / water mixing operation is started.

  In the air-water mixing operation state, when the water absorption level WL further rises and reaches the lowest water level LWL (an example of the first predetermined water level), the tip 21b of the air-water mixing air pipe 21 that has been held open until then. Since (an example of the first air supply port) is closed by the opening / closing means 23 and air is not sucked from the first opening 25, drainage at the rated drainage amount starts. That is, the start of full operation.

  If the water absorption level WL is further increased after the full operation, the full operation is continued.

  On the other hand, when the total amount of water is discharged and the drainage amount of the pump 1 exceeds the inflow amount of rainwater or the like into the suction tank 2 and the water absorption level WL starts to fall and falls below the minimum water level LWL (an example of the first predetermined water level). The tip 21b (an example of the first air supply port) of the air / water mixing air pipe 21 that has been kept closed until then is opened by the opening / closing means 23, and the suction of air from the first opening 25 is started. Then, the whole operation shifts to the air / water mixing operation.

  When the water absorption level WL is further lowered by the air-water mixing operation, the air suction amount gradually increases in accordance with the decrease in the water absorption level WL, and instead the water amount gradually decreases, so the drainage amount gradually decreases. . Then, when the water absorption level WL further decreases, falls below the pumping start water level RWL and the re-pumping start water level CWL, and finally falls below the pumping cutoff water level SWL (an example of the second predetermined water level), it is held closed until then. The front end 22 b (an example of the second air supply port) of the pumped-up water blocking air pipe 22 is opened by the opening / closing means 24. Since the pressure in the second opening 26 is reduced by the flow of water on the inflow side of the impeller 11 and becomes a negative pressure lower than the atmospheric pressure, the pressure from the second opening 26 also passes through the pumping-off cutoff air pipe 22. Air is sucked in, the mixing ratio of water and air becomes very high, the impeller 11 cannot suck in water, and drainage stops. That is, the operation is switched from the air / water mixing operation to the pumping off operation. It should be noted that air necessary for shutting off pumping is sucked into the casing 3 when a gap of a certain level or more is formed between the tip 22b of the pumping shutoff air pipe 22 and the water surface, so that pumping is actually shut off. The water level is slightly lower than the water level at which the tip 22b of the pumping-off air pipe 22 is submerged, but the water level including the pumping-off water level SWL in this specification is a water absorption having a width including these. This is a concept representing the position WL.

  When the water absorption level WL rises during the pumping shutoff operation (standby operation), since there is water in the casing 3 above the impeller 11, the water absorption level WL is the pumping shutoff water level SWL (an example of the second predetermined water level). (The tip 22b of the pumping-off air pipe 22 that has been held in the open state until then is closed by the opening / closing means 24, so that no air is sucked in from the second opening 26). At the time of arrival, the impeller 11 starts pumping water while sucking in air (air sucked from the first opening 25 through the air / water mixing air pipe 21). The air-water mixing operation is resumed.

  In this way, the pump 1 can continue the operation between the idle operation after start-up and the empty operation after the drainage (pumping shut-off operation) and the full operation, regardless of the water absorption level WL. The transition between operation and full operation is smooth, and vortex generation, pump 1 vibration, and excessive change in shaft torque are suppressed.

  As described above, the preceding standby operation pump 1 of the present embodiment includes the casing 3 having the suction port 8 opened in the suction water tank 2 at the lower end, the impeller 11 disposed in the casing 3, and the water absorption level WL is the lowest water level LWL ( An example of the first predetermined water level) The tip 21b of the air / water mixing air pipe 21 for lowering the amount of drainage by pumping water while introducing air into the casing 3 below the impeller 11 in the following state (first) Air) and the intake water level WL is lower than the lowest water level LWL, and when the pumping cutoff water level SWL (an example of a second predetermined water level) is reached, air is introduced into the casing 3 below the impeller 11. The tip 22b (an example of the second air supply port) of the pumping-off air pipe 22 for shutting off the pumping is provided, and the tip 21b of the two kinds of air-water mixing air pipes 21 and the pumping-off air pipe 22 tip 22b Since the air / water mixing air pipe 21 that communicates with the inside of the casing 3 and the pumping-off air pipe 22 (an example of an air pipe) are provided, an amount of air sufficient for pumping-off can be introduced only at the time of pumping-off. In addition, it is possible to easily optimize the amount of air introduced during the air / water mixing operation, and it is possible to suppress the generation of vortices and vibrations compared to the case where air is introduced only by the air / water mixing air supply port. . As a result, there is no need to increase the strength of the pump 1, the pump 1 can be reduced in weight, and there is a case where it is not necessary to increase the floor strength of the drainage station.

  Further, the air / water mixing air pipe 21 that communicates the tip 21b of the air / water mixing air pipe 21 with the inside of the casing 3, and the pumping water that communicates the tip 22b of the pumping-off air pipe 22 and the inside of the casing 3 with each other. Since the shut-off air pipe 22 is provided, the air amount introduced at the time of the air-water mixing operation and the air amount introduced at the time of shutting off the pumping can be easily set, and the above-described effects can be easily realized.

  By the way, the air pipe whose opening position in the casing 3 is closer to the impeller 11 sucks more air when the water level is low. Further, in order to shut off the pumping, it is necessary to break the contact between the impeller 11 and water by filling the cross section (passage) of the casing 3 below the impeller 11 with air. Considering that the air in the lower casing 3 moves upward, it is necessary to introduce a large amount of air in a short time. And the opening (second opening) 26 position in the casing 3 of the pumping-off air pipe 22 that communicates the tip 22b of the pumping-off air pipe 22 and the inside of the casing 3 is the air-water mixing air pipe 21. Since the top (21) of the air / water mixing air pipe 21 that communicates the tip 21b of the casing 3 with the inside of the casing 3 is above the position (opening) 25 in the casing 3, that is, close to the impeller 11, Occasionally, air can be introduced (intake) efficiently and effectively into the casing 3 below the impeller 11 from the tip 22b of the pumping-off air pipe 22 through the pumping-off air pipe 22. When water is descending (during air-water mixing operation), pumping can be shut off accurately and stably. Further, the pumping cutoff water level SWL is determined by the height of the opening 25 in the casing 3 of the air / water mixing air pipe 21 (if the height of the opening 25 is low, the pumping water is shut off at a lower water level). Therefore, when shutting off the pumping at a low water level, it is desirable that the position of the opening 25 in the casing 3 of the air / water mixing air pipe 21 is on the lower side. And since the position of the opening 25 in the casing 3 of the air / water mixing air pipe 21 can be made lower below the position of the opening 26 in the casing 3 of the pumping-off air pipe 22, the pumping can be performed at a lower water level. Can be blocked. That is, the positional relationship between the position of the opening 25 in the casing 3 of the air / water mixing air pipe 21 and the position of the opening 26 in the casing 3 of the pumping-off air pipe 22 is suitable for pumping-off at a low water level.

  In the preceding standby operation pump 1 of the present embodiment, the position of the opening 26 in the casing 3 of the pumping-off air pipe 22 that communicates the tip 22b of the pumping-off air pipe 22 with the inside of the casing 3 is set to the air pipe 21 for mixing air and water. By shifting in the circumferential direction of the casing 3 with respect to the position of the opening 25 in the casing 3 of the air / water mixing air pipe 21 that communicates the tip 21b of the casing 3 with the inside of the casing 3, the local portion is located in the casing 3 below the impeller 11. In particular, the position where the mixing ratio of water and air is high, that is, the position of the opening 25 in the casing 3 of the air / water mixing air pipe 21 that communicates the tip 21b of the air / water mixing air pipe 21 and the inside of the casing 3 is true. Avoiding the upper position, when pumping off, the tip 22b of the pumping shut-off air pipe 22 passes through the pumping shut-off air pipe 22 to be more efficient in the casing 3 below the impeller 11 And effectively introducing air is adapted to be able to (intake). In this embodiment, the opening 26 in the casing 3 of the pumping-off air pipe 22 is shifted by 90 ° downstream from the opening 25 in the casing 3 of the air / water mixing air pipe 21 in the rotational direction of the impeller 11. However, the present invention is not limited to this, and it is desirable that water containing a lot of air does not reach the vicinity of the opening 26, and the opening 26 is the rotation of the impeller 11 with respect to the opening 25. It can be set as the position where the water containing much air does not reach on the upstream side in the direction. Further, when the opening 26 is provided on the downstream side in the rotation direction of the impeller 11 with respect to the opening 25, it is desirable to shift the opening 26 by 10 ° or more in the circumferential direction.

  Further, since the pumping shut-off air pipe 22 is provided with the opening / closing means 24, the pumping can be shut off when the water absorption level WL becomes the pumping shut-off water level SWL, and variations in the pumping shut-off water level can be prevented. .

  Further, since the tip 22b of the pumping-off air pipe 22 is provided so as to be submerged at the pumping-off cutoff water level SWL, this configuration becomes the opening / closing means 24, and the tip 22b of the pumping-off cutoff air pipe 22 is made of water in the suction water tank 2. It can be opened and closed, and a control mechanism for opening and closing the tip 22b of the pumping-off air pipe 22 becomes unnecessary.

  Further, the pressure reducing means 27 for reducing the fluid pressure in the vicinity of the opening 26 in the casing 3 of the pumped water blocking air pipe 22 is provided on the inner surface of the casing 3, so that the pumped water blocking air is supplied from the tip 22 b of the pumped water blocking air pipe 22. Air can be stably introduced through the pipe 22, and the pumping-off operation can be switched more reliably.

  Further, since the pressure reducing means 27 is a support plate (rib) 16a for fixing the lower end bearing 16 of the main shaft 13 to which the impeller 11 is attached to the inner surface of the casing 3, the casing 3 structure below the impeller 11 is simplified, The pump 1 can be reduced in weight.

  In addition, since the air / water mixing air pipe 21 is provided with the opening / closing means 23, the air / water mixing operation is performed, and the air / water mixing air pipe 21 is closed by the opening / closing means 23 when the water absorption level WL is equal to or higher than the minimum water level LWL. The pump can be completely stopped, and the full operation at the rated drainage amount of the pump 1 can be performed at the minimum water level LWL or higher.

  Further, since the tip 21b of the air / water mixing air pipe 21 is provided so as to be submerged at the lowest water level LWL, this configuration becomes the opening / closing means 23, and the tip of the air / water mixing air pipe 21 is made of water in the suction water tank 2. 21b can be opened and closed, and a control mechanism for opening and closing the tip 21b of the air / water mixing air pipe 21 is not required.

  Further, since the vortex generation preventing plate 28 is provided on the outer surface of the casing 3 below the impeller 11, the generation of vortices can be suppressed when the water absorption level WL is a low water level equal to or lower than the pumping cutoff water level SWL. Pumping can be shut off and drained to a lower water level.

  Next, the preceding standby operation pump 1A of the second embodiment will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same part as the prior | preceding standby operation pump 1 of 1st Example, and the overlapping description is abbreviate | omitted.

  In FIG. 3, the preceding standby operation pump 1 </ b> A includes a substantially straight tubular air / water mixing air pipe 21 </ b> A and a pumping-off air pipe 22 </ b> A. In the air / water mixing air pipe 21 </ b> A, the vicinity of the upper end is disposed above the floor 19. And it is extended in the suction water tank 2 through the hole 20, and the lower end 21 </ b> Aa is connected to the first opening 25. The air / water mixing air pipe 21A arranged above the floor 19 is bent in an inverted U shape, and the upper end 21Ab of the air / water mixing air pipe 21A faces downward and is always open to the atmosphere.

  On the other hand, the pumping cutoff air pipe 22 </ b> A is disposed above the floor 19 in the vicinity of the upper end. And it is extended in the suction water tank 2 through the hole 20, and the lower end 22 </ b> Aa is connected to the second opening 26. The pumping off air pipe 22A arranged above the floor 19 is provided with an on / off valve (solenoid valve) 24A as an opening / closing means, and the upper end 22Ab of the pumping off air pipe 22A is connected to the atmosphere via the on / off valve 24A. It is open inside.

  In addition, pressure reducing means 27 </ b> A is provided on the inner surface of the suction pipe 6 to reduce the fluid pressure in the vicinity of both the first opening 25 and the second opening 26. The pressure reducing means 27A is a support plate (rib) of the lower end bearing 16, and the relative position in the circumferential direction with respect to the first opening 25 and the second opening 26 at the outer end is the position shown in FIG. The end portion is constituted by the outer end portion of the support plate 16Aa having a height (vertical width) below the impeller 11 and covering the height range of the first opening 25 and the second opening 26.

  The preceding standby operation pump 1A of the present embodiment exhibits the same function as the preceding standby operation pump 1A of the first embodiment by controlling the opening / closing valve 24A based on a water level sensor or the like that detects the water absorption level WL. Can do. However, the air / water mixing air pipe 21A is always open to the atmosphere.

  Further, since the pressure reducing means 27A for reducing the fluid pressure in the vicinity of both the first opening 25 and the second opening 26 is provided, the air opening for air / water mixing is also provided for the first opening 25. The air can be stably introduced from the tip 21b of the gas 21 through the air / water mixing air pipe 21A.

It is a longitudinal cross-sectional view of the advance standby operation pump which shows 1st Example of this invention. It is a cross-sectional view of the air introduction part in the preceding standby operation pump of FIG. It is a longitudinal cross-sectional view of the preceding standby operation pump showing the second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A Advance standby operation pump 2 Suction water tank 3 Casing 8 Suction port 11 Impeller 21 Air-water mixing air pipe 21b The front-end | tip of an air-water mixing air pipe (an example of a 1st air supply port)
22 Air pipe for pumping off water 22b Tip of air pipe for pumping off water (example of second air supply port)
25 First opening 26 Second opening

Claims (2)

  In the casing below the impeller in a state where a casing having a suction port opened in the suction water tank, an impeller disposed inside the casing, and a water level of the suction water tank below a first predetermined water level A first air supply port for reducing the amount of drainage by pumping water while introducing air, and the impeller when the water level of the suction water tank becomes a second predetermined water level lower than the first predetermined water level. A second air supply port for shutting off pumping by introducing air into the lower casing; and an air pipe for communicating the two types of air supply ports with the inside of the casing, The opening position in the casing of the air pipe that connects the second air supply port and the inside of the casing is above the opening position in the casing of the air pipe that connects the first air supply port and the inside of the casing. Preceding standby operation pump, characterized in that.   The opening position in the casing of the air pipe that communicates the second air supply port and the inside of the casing with respect to the opening position in the casing of the air pipe that communicates the first air supply port and the inside of the casing. A preceding standby operation pump characterized by being shifted in the circumferential direction of the casing.

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