JP6504247B2 - Suction cover used for horizontal axis submersible pump and horizontal axis submersible pump - Google Patents

Description

  The present disclosure relates to a horizontal axis submersible pump as an internal water removal facility installed in a culvert or the like and used for pumping rainwater, sewage, etc., and a suction cover used for the horizontal axis submersible pump.

  2. Description of the Related Art Conventionally, there has been an increase in the construction of drainage facilities where a low water level horizontal axis submersible pump (horizontal axis axial flow submersible pump) is adopted as a drainage pump for rainwater or the like by modifying the pump equipment into a detachable structure.

  In addition, for example, at a place where the main river and the tributaries join, the on-off gate is installed on the tributary side, and the on-off gate is closed at the time of heavy rain etc. Restraint. At that time, in order to forcibly drain the water flowing from the upstream of the tributary, a pump gate in which a horizontal axis submersible pump is attached to an open / close gate is often used. And, a pump gate often uses a horizontal axis submersible pump to drain a large volume. Patent Document 1 discloses a pump gate in which a horizontal axis submersible pump is provided with a suction bell mouth (suction cover) so that water can be drained to a low water level.

JP 2003-003450 A

  The horizontal axis submersible pump disclosed in Patent Document 1 is temporarily stopped and temporarily stopped when the water level becomes lower than the water level during operation with the impeller completely submerged, such as during total drainage operation. , It is restarted when the inflow volume increases and the water level rises. As described above, if the pump is repeatedly turned on and off according to the water level, the operation management becomes complicated, the frequency of start-up becomes frequent, and the load on the submersible motor becomes large.

  Therefore, the present invention provides a horizontal axis submersible pump capable of maintaining operation at the rated rotation speed and suppressing repetition of stop and start of the pump even if the water level on the suction side is below the water level at the time of total drainage operation. The purpose is to

  A horizontal axis submersible pump according to one aspect of the present invention is provided on a casing having an inlet and an outlet, an impeller supported in the casing, an inlet cover connected to the inlet, and an inlet cover A first suction opening opened at a position lower than the upper end of the impeller, and at least one of a suction cover and a casing, provided upstream of the impeller and open at a position higher than the upper end of the first suction opening And a second suction opening.

  As a result, the horizontal axis submersible pump operates while sucking in air even in the operation mode in which the impeller is not completely submerged, so suction is maintained while maintaining the operation at the rated speed of the submersible motor that drives the impeller. It is possible to suppress the lowering speed or rising speed of the water level on the side. Therefore, the ON / OFF repetition frequency of the submersible motor can be reduced.

  Also, the suction cover has an upper wall and a side wall extending downward from the upper wall, and the front edge of the upper wall has a position higher than both ends of the front edge, and the second suction opening May be an opening surrounded by a front edge and a straight line connecting both ends of the front edge.

  Thereby, the suction cover can suppress the generation of the air suction vortex from the water surface, and can suppress the vibration and the noise. Further, for example, when the water level on the suction side decreases and the water level of the operation mode of the total drainage becomes the water level of the operation mode of the air / water mixed drainage, the intake area at the second suction opening is expanded, so the air suction amount It is possible to increase the number of operation modes smoothly and smoothly.

  In addition, the suction cover has an upper wall, a side wall extending downward from the upper wall, and a front wall extending downward from the upper wall, and the second suction opening penetrates the front wall It may be a hole.

  Thereby, the suction cover can suppress the generation of the air suction vortex from the water surface, and can suppress the vibration and the noise. Further, for example, when the water level on the suction side decreases and the water level of the operation mode of the total drainage becomes the water level of the operation mode of the air / water mixed drainage, the intake area at the second suction opening is expanded, so the air suction amount It is possible to increase the number of operation modes smoothly and smoothly. Furthermore, while the suction cover can allow the fluid (water or air) coming from the upstream side to flow into the suction cover, it can inhibit the foreign matter contained in the fluid from flowing into the suction cover.

  The suction cover has an upper wall, a side wall extending downward from the upper wall, and a front wall extending downward from the upper wall, and the first suction opening is a lower end of the front wall The second suction opening is in communication with the first suction opening, and is surrounded by at least one notch formed in the front wall and a straight line connecting the lower end of the front wall It may be an open aperture.

  Thereby, the suction cover can suppress the generation of the air suction vortex from the water surface, and can suppress the vibration and the noise. Further, for example, when the water level on the suction side decreases and the water level of the operation mode of the total drainage becomes the water level of the operation mode of the air / water mixed drainage, the intake area at the second suction opening is expanded, so the air suction amount It is possible to increase the number of operation modes smoothly and smoothly. Furthermore, while the suction cover can allow the fluid (water or air) coming from the upstream side to flow into the suction cover, it can inhibit the foreign matter contained in the fluid from flowing into the suction cover.

  The suction cover has an upper wall and a side wall extending downward from the upper wall, and the first suction opening is an opening surrounded by the front edge of the upper wall and the lower end of the side wall, The second suction opening is in communication with the first suction opening and is an opening surrounded by at least one notch formed in the upper wall and a straight line connecting the front edge of the upper wall or the first suction opening The opening may be in communication and be surrounded by at least one notch formed in the side wall and a straight line connecting the lower ends of the side wall.

  Thereby, the suction cover can suppress the generation of the air suction vortex from the water surface, and can suppress the vibration and the noise. Further, for example, when the water level on the suction side decreases and the water level of the operation mode of the total drainage becomes the water level of the operation mode of the air / water mixed drainage, the intake area at the second suction opening is expanded, so the air suction amount It is possible to increase the number of operation modes smoothly and smoothly. Furthermore, while the suction cover can allow the fluid (water or air) coming from the upstream side to flow into the suction cover, it can inhibit the foreign matter contained in the fluid from flowing into the suction cover.

  The suction cover may have an upper wall and a side wall extending downward from the upper wall, and the second suction opening may be an opening formed in the upper wall or the side wall.

  Thereby, the suction cover can suppress the generation of the air suction vortex from the water surface, and can suppress the vibration and the noise. Further, for example, when the water level on the suction side decreases and the water level of the operation mode of the total drainage becomes the water level of the operation mode of the air / water mixed drainage, the intake area at the second suction opening is expanded, so the air suction amount It is possible to increase the number of operation modes smoothly and smoothly.

  Furthermore, an intake pipe is provided, which is an intake port having one end connected to the suction cover or casing and the other end opened, the suction cover comprising an upper wall and a side wall extending downward from the upper wall; The second suction opening may be an inlet.

  Thereby, air can be suitably made to flow in in the suction cover also in the operation mode below the water level of the operation mode of all the drainage.

  In addition, the front edge of the upper wall of the suction cover or the lower end of the front wall extending downward from the upper wall of the suction cover is located 10 to 25% above the lower end of the impeller in diameter ratio of the impeller It is good also as things.

  As a result, the operation in the operation mode of the entire amount drainage can be performed until the low water level, and particularly in the operation mode of the total amount drainage, the generation of the air suction vortex can be more suitably suppressed.

  Furthermore, a flap gate may be provided on the side of the discharge port of the casing and can be opened and closed by the pressure of the fluid discharged from the discharge port.

  As a result, in each operation mode of total drainage and air / water mixed drainage, the flap gate is always open, water is discharged according to each operation mode, and in the idling operation mode at a water level lower than that, the flap gate is blocked. As a result, the fluid is likely to circulate in the casing. Further, since the flap gate is opened and closed by the discharge pressure, there is no need to separately provide a drive device and a control device for opening and closing the flap gate, and the configuration can be simplified.

  Furthermore, an air venting mechanism may be provided which exhausts the air in the casing to the outside when the internal pressure of the casing reaches a predetermined pressure.

  Thereby, for example, when the water level rises from the operation mode of idling or the operation mode of air-water mixture drainage and shifts to another operation mode, the air retained in the casing can be suitably discharged. The load on the submersible motor can be reduced.

  In addition, the suction cover used in the horizontal axis submersible pump according to one aspect of the present invention is extended downward from the discharge opening, the upper wall, the side wall extending downward from the upper wall, and the upper wall The first suction opening surrounded by the front wall, the lower end of the front wall and the lower end of the side wall, the at least one notch formed in the front wall communicating with the first suction opening, and the lower end of the front wall And a second suction opening which is an opening surrounded by a straight line.

  Thereby, the suction cover can suppress the generation of the air suction vortex from the water surface, and can suppress the vibration and the noise. Further, for example, when the water level on the suction side decreases and the water level of the operation mode of the total drainage becomes the water level of the operation mode of the air / water mixed drainage, the intake area at the second suction opening is expanded, so the air suction amount It is possible to increase the number of operation modes smoothly and smoothly. Furthermore, while the suction cover can allow the fluid (water or air) coming from the upstream side to flow into the suction cover, it can inhibit the foreign matter contained in the fluid from flowing into the suction cover.

  Furthermore, the suction cover used in the horizontal axis submersible pump according to another aspect of the present invention has a discharge opening, an upper wall, a side wall extending downward from the upper wall, a front edge of the upper wall and a lower end of the side wall And an opening surrounded by a first suction opening surrounded by the first suction opening, at least one notch formed in the upper wall in communication with the first suction opening, and a straight line connecting the front edge of the upper wall, or 1 has a second suction opening which is in communication with the suction opening and which is an opening surrounded by at least one notch formed in the side wall and a straight line connecting lower ends of the side wall.

  Thereby, the suction cover can suppress the generation of the air suction vortex from the water surface, and can suppress the vibration and the noise. Further, for example, when the water level on the suction side decreases and the water level of the operation mode of the total drainage becomes the water level of the operation mode of the air / water mixed drainage, the intake area at the second suction opening is expanded, so the air suction amount It is possible to increase the number of operation modes smoothly and smoothly. Furthermore, while the suction cover can allow the fluid (water or air) coming from the upstream side to flow into the suction cover, it can inhibit the foreign matter contained in the fluid from flowing into the suction cover.

  According to the present invention, there is provided a horizontal axis submersible pump capable of maintaining operation at the rated rotation speed and suppressing repetition of stop and start of the pump even if the water level on the suction side is below the water level at the time of total drainage operation. can do.

FIG. 1 is a view showing a configuration of a horizontal axis submersible pump according to an embodiment of the present invention. FIG. 2 is a view showing the shape of the suction cover in the first embodiment. FIG. 3 is a view showing another shape of the suction cover in the first embodiment. FIG. 4 is a view showing another shape of the suction cover in the first embodiment. FIG. 5 is a diagram showing a configuration of a pump gate system using a horizontal axis submersible pump. FIG. 6 is a view for explaining the operation mode of the horizontal axis submersible pump according to the first embodiment. FIG. 7 is a diagram showing a pump operation in the total amount drainage mode in the first embodiment. FIG. 8 is a diagram showing a pump operation in the air-water mixing and discharging mode in the first embodiment. FIG. 9 is a diagram showing the pump operation in the idling mode in the first embodiment. FIG. 10 is a view showing a configuration of an air extracting mechanism installed in the horizontal axis submersible pump. FIG. 11 is a view showing the shape of the suction cover in the second embodiment. FIG. 12 is a view showing the shape of the intake unit in the second embodiment. FIG. 13 is a view showing another shape of the intake unit in the second embodiment. FIG. 14A is a view showing another shape of the intake unit in the second embodiment. FIG. 14B is a view showing another shape of the intake unit in the second embodiment. FIG. 15 is a view showing another shape of the intake unit in the second embodiment. FIG. 16 is a view for explaining the operation mode of the horizontal axis submersible pump according to the second embodiment. FIG. 17 is a diagram showing a pump operation in the total amount drainage mode in the second embodiment. FIG. 18 is a diagram showing a pump operation in the air-water mixing and discharging mode in the second embodiment. FIG. 19 is a diagram showing the pump operation in the idling mode in the second embodiment. FIG. 20 is a view showing an outer shape of a horizontal axis submersible pump according to a third embodiment. FIG. 21 is a view showing another outer shape of the horizontal axis submersible pump according to the third embodiment. FIG. 22 is a diagram for explaining the operation mode of the horizontal axis submersible pump according to the third embodiment. FIG. 23 is a view showing a pump operation at the time of the total amount drainage mode in the third embodiment. FIG. 24 is a view showing a pump operation in the air-water mixing and discharging mode in the third embodiment. FIG. 25 is a diagram showing a pump operation in the idling mode in the third embodiment. FIG. 26 is a view showing an outer shape of a horizontal axis submersible pump according to a fourth embodiment. FIG. 27 is a view showing another outer shape of the horizontal-axis submersible pump in the fourth embodiment. FIG. 28 is a view showing another outer shape of the horizontal-axis submersible pump in the fourth embodiment. FIG. 29 is a view for explaining the operation mode of the horizontal axis submersible pump according to the fourth embodiment. FIG. 30 is a view showing a pump operation at the time of the total quantity drainage mode in the fourth embodiment. FIG. 31 is a diagram showing a pump operation in the air / water mixing / discharging mode in the fourth embodiment. FIG. 32 is a diagram showing the pump operation in the idling mode in the fourth embodiment. FIG. 33 is a view showing an outer shape of a horizontal axis submersible pump in the fifth embodiment. FIG. 34A is a view showing the configuration of the air adjustment mechanism in the fifth embodiment. FIG. 34B is a view showing another configuration of the air adjustment mechanism in the fifth embodiment. FIG. 35 is a view for explaining the operation mode of the horizontal axis submersible pump according to the fifth embodiment. FIG. 36 is a diagram showing a pump operation at the time of the total amount drainage mode in the fifth embodiment. FIG. 37 is a diagram showing a pump operation in the air / water mixing / discharging mode in the fifth embodiment. FIG. 38 is a diagram showing a pump operation in the idling mode in the fifth embodiment. FIG. 39 is a diagram showing a configuration of a horizontal axis submersible pump according to a sixth embodiment. FIG. 40A is a front view of an essential part of the impeller. FIG. 40B is a developed view of the impeller at the height position of the front edge of the suction cover. FIG. 41 is a view showing the shape of the suction cover in the sixth embodiment. FIG. 42 is a graph showing the performance curve of the horizontal axis submersible pump. FIG. 43 is a diagram for explaining an operation mode of a horizontal axis submersible pump according to a sixth embodiment. FIG. 44 is a diagram showing a pump operation at the time of whole quantity drainage mode in the sixth embodiment. FIG. 45 is a diagram showing a pump operation in the idling mode in the sixth embodiment. FIG. 46 is a view showing the shape of a suction cover as another embodiment. FIG. 47 is a view showing the shape of a suction cover as another embodiment. FIG. 48 is a view showing the shape of a suction cover as another embodiment. FIG. 49 is a view showing the shape of a suction cover as another embodiment. FIG. 50 is a view showing the shape of a suction cover as another embodiment. FIG. 51 is a view showing the shape of a suction cover as another embodiment. FIG. 52 is a view showing the shape of a suction cover as another embodiment. FIG. 53 is a view showing the shape of a suction cover as another embodiment. FIG. 54 is a view showing the shape of a suction cover as another embodiment. FIG. 55 is a view showing the shape of a suction cover as another embodiment.

First Embodiment
FIG. 1 is a side sectional view showing the configuration of a horizontal axis submersible pump 1 according to a first embodiment of the present invention. The horizontal axis submersible pump 1 is a horizontal axis axial flow submersible pump capable of draining a large volume, and includes a casing 2, an impeller 3, a main shaft 4, a guide vane 5, and an underwater motor 6. Equipped with

  The casing 2 is a cylinder having an inlet and an outlet, through which fluid (water and air) passes. The impeller 3, the guide vanes 5 and the submersible motor 6 are disposed inside the casing 2 from the suction side. The impeller 3 is selected according to the specifications of the drainage station, and is, for example, an axial flow vane or a mixed flow vane. The main shaft 4 transmits the rotational force generated by the submersible motor 6 to the impeller 3, one end thereof is connected to the submersible motor 6, and the other end is connected to the impeller 3. That is, the impeller 3 is supported by the submersible motor 6 held by the casing 2 via the main shaft 4. The guide vanes 5 define the flow direction of the fluid flowing in the casing 2.

  Furthermore, the horizontal axis submersible pump 1 may include a flap gate 9 supported openably and closably on the discharge side of the casing 2. The flap gate 9 may be provided directly or indirectly at the outlet of the casing 2. For example, the casing 2 and the flap gate 9 may be connected to each other via a sluice wall to which the horizontal axis submersible pump 1 is attached. Here, as an example of a water gate wall, the gate door of a pump gate system which is mentioned later is mentioned. The flap gate 9 is closed by its own weight when the discharge pressure of the horizontal axis submersible pump 1 is low, and when the discharge pressure is high, drainage is enabled by opening the upper fulcrum as an axis. In addition, it is also possible to drain and connect discharge piping to the discharge side of the casing 2 according to a use.

  Further, the horizontal axis submersible pump 1 is provided with a suction cover 7 on the suction side of the casing 2 with the opening 8 directed downward. The suction cover 7 is made of, for example, a casting, and guides the fluid sucked from the opening 8 to the suction port of the casing 2.

  FIG. 2 is a three-sided view showing the shape of the suction cover 7 in the present embodiment. The suction cover 7 has an upper wall 10, two side walls 11 extending downward from both side ends of the upper wall 10, and a flange 12 connected to the casing 2 and having a discharge opening. The upper wall 10 is inclined downward toward the suction side (left direction in the side view). The lower ends of the side walls 11 are respectively inclined from both ends of the front edge 13 of the upper wall 10 to the lower vicinity of the casing 2 of the horizontal axis submersible pump 1.

  The opening 8 of the suction cover 7 is a first suction opening in the present embodiment, which is provided in an inclined state such that the suction side is higher than the other side. The front edge 13 of the upper wall 10 forms a convex portion whose central portion is higher than both ends. The intake portion 14 of the suction cover 7 is a space surrounded by a straight line (two-dot chain line) connecting both end portions of the front edge 13 and the convex front edge 13, and is a second suction opening in this embodiment. is there. The front edge 13 is not limited to a straight line, and the central portion of the front edge 13 may protrude toward the suction side. Further, according to the specifications of the drainage station and the horizontal axis submersible pump 1, the start end 14a at the highest position of the intake unit 14 and the end end 14b at the lowest position can be operated in the air / water mixed discharge mode described later. Set to position.

  FIG. 3 is a two-face view showing another shape of the suction cover 7 in the present embodiment. In the present embodiment, the shape of the suction cover 7 is not limited to that shown in FIG. 2, but may be that shown in FIG. The suction cover 7 shown in FIG. 3 has a front wall 15 extending downward from the front edge 13 of the upper wall 10. In this case, the second suction opening in the present embodiment is a plurality of intake holes 16 penetrating the front wall 15. The lower end (end) of the side wall 11 has a predetermined inclination angle from the lower end of the front wall 15 toward the flange 12. The extended length of the front wall 15 is appropriately set according to the operation conditions of the air / water mixture discharge mode and the idling mode described later. Further, the shape of the intake hole 16 can be appropriately selected from a circle, a long hole, a slit, and the like, and the hole diameter of the intake hole 16, the width of the slit, and the like are appropriately determined according to the operating conditions.

  FIG. 4 is a two-face view showing another shape of the suction cover 7 in the present embodiment. The suction cover 7 shown in FIG. 4 has a front wall 15 with the front edge 13 of the upper wall 10 horizontal and extending downward from the front edge 13. The front wall 15 has at least one or more notches communicating with the opening 8, and the shape of the notches as a whole is serrated or wavy. In this case, the second suction opening in the present embodiment is the intake portion 14 as an opening surrounded by a notch and a straight line (two-dot chain line) connecting the lower end of the front wall 15. The shape of the side wall 11 and the extension length of the front wall 15 are the same as those of the suction cover 7 shown in FIG.

  FIG. 5 is a schematic view showing a configuration of a pump gate system 17 using the horizontal axis submersible pump 1. The pump gate system 17 includes a pump gate 19, a rack rod 21 suspended from the ceiling wall 20 and lifting the gate door 18, and an opening / closing unit 22 for moving the pump gate 19 vertically by moving the rack rod 21 vertically. .

  The pump gate 19 detachably incorporates the horizontal axis submersible pump 1 into the gate door 18 and opens and closes a water channel such as a river, and the water from the upstream side (left in the figure) to the downstream side (right in the figure) Drain. Specifically, in the normal state, with the gate door 18 raised, water in the water channel on the pump suction side (upstream side) is naturally drained to the water channel on the pump discharge side (downstream side). On the other hand, when the outside water level on the downstream side rises due to heavy rain etc., the gate door 18 is lowered by the drive of the opening / closing device 22 to close the water channel, and the horizontal axis submersible pump 1 makes the upstream water downstream. Force drainage. Although the pump gate system 17 in the present embodiment vertically lowers the pump gate 19 to close the water channel, the water channel may be closed by a known technique such as rocking or rotation.

  Next, the operation mode of the horizontal axis submersible pump 1 used for the pump gate system 17 will be described. FIG. 6 is a diagram for explaining the operation mode of the horizontal axis submersible pump 1. In addition, in FIG. 6, although the shape of the suction cover 7 demonstrates as what is shown in FIG. 3, it is the same even if it is the suction cover 7 shown in FIG. 2 or FIG.

  The horizontal axis submersible pump 1 has three operation modes based on two suction level water levels H and M (H> M) set in advance. Specifically, the total amount drainage mode M1, the air-water mixing discharge mode M2, and the idling mode M3. The total amount drainage mode M1 is performed when the water level on the suction side exceeds the water level H. The air / water mixed discharge mode M2 is performed when the water level on the suction side is below the water level H and exceeds the water level M. The idling mode M3 is performed when the water level on the suction side is equal to or less than the water level M. Although not shown, when the water level on the suction side is less than or equal to a specific water level L (L <M), the horizontal axis submersible pump 1 stops its operation.

  When the suction cover 7 has the shape shown in FIG. 3, the water level H is set to the position of the upper end 16 a of the suction hole 16 of the suction cover 7. The water level M is set at the upper end of the opening 8 of the suction cover 7. Further, the water level L is set to the upper limit of the water level where sufficient water can not be supplied to the submersible motor 6 even when the impeller 3 is rotating. When the suction cover 7 has the shape shown in FIG. 2, the water level H is set to the position of the start end 14 a of the suction portion 14 of the suction cover 7, and the water level M is set to the position of the end 14 b of the suction portion 14 It is set.

<Whole drainage mode>
FIG. 7 is a view for explaining the operation of the horizontal axis submersible pump 1 when the operation mode is the total drainage mode M1 (suction side water level> water level H). The total amount drainage mode M1 is an operation mode in which the entire amount of water sucked on the upstream side is discharged to the downstream side. When the water level on the gate downstream side (discharge side) rises due to heavy rain or the like, the gate door 18 is lowered to close the water passage in order to suppress the backflow. Then, when the water level on the gate upstream side (suction side) exceeds the water level H, the horizontal axis submersible pump 1 is activated, and the horizontal axis submersible pump 1 is operated at the rated speed in the total drainage mode M1 and is downstream Drain. At this time, all the openings (intake holes 16 and openings 8) communicating with the inside of the horizontal axis submersible pump 1 are submerged, and the discharge pressure of the flap gate 9 on the discharge side is opened by the discharge pressure of the horizontal axis submersible pump 1 It has become. Here, the operation start timing of the horizontal axis submersible pump 1 may be determined after the controller (not shown) detects that the water level H is exceeded by a known water level gauge or the like, or the water level may actually be The determination may be made automatically based on a preset start time or the like without detecting H.

<Air-water mixed discharge mode>
FIG. 8 is a view for explaining the operation of the horizontal axis submersible pump 1 when the operation mode is the air / water mixture discharge mode M2 (water level H ≧ suction side water level> water level M). As the horizontal axis submersible pump 1 drains the stored water on the upstream side of the gate in the total drainage mode M1, when the water level on the upstream side of the gate gradually falls and falls below the water level H, the operation mode shifts to the air / water mixed discharge mode M2. Do. The air / water mixture discharge mode M2 is an operation mode in which drainage is performed in operation at the rated speed while sucking in a small amount of air with water.

  As a specific water level, although a part or all of the suction hole 16 of the suction cover 7 is open to the atmosphere, the opening 8 is a submerged water level. By setting the upper end 16a of the suction hole 16 of the suction cover 7 to the water level H, air can be sucked from the suction hole 16 while sucking water from the opening 8. The amount of displacement is determined by the relationship between the water level and the amount of intake air. By providing this air-water mixture discharge mode M2, unstable operation at a low water level can be alleviated.

  In the air-water mixture discharge mode M2, the discharge pressure of the horizontal axis submersible pump 1 is lower than that in the total water discharge mode M1. However, the flap gate 9 remains open.

<Idling mode>
FIG. 9 is a view for explaining the operation of the horizontal axis submersible pump 1 when the operation mode is the idling mode M3 (water level M ≧ suction side water level> water level L). When the horizontal axis submersible pump 1 continues to drain, the water level further drops and becomes lower than the water level M, the operation mode shifts from the air / water mixture discharge mode M2 to the idling mode M3. The idling mode M3 is a mode in which a so-called standby operation is performed, and is an operation mode in which the operation at the rated rotational speed is maintained while drawing a large amount of air with water.

  A specific water level is a water level in which a portion of the opening 3 of the suction cover 7 is open to the atmosphere but a portion of the impeller 3 is submerged. By setting the upper end of the opening 8 of the suction cover 7 to the water level M, a large amount of air can be sucked from the suction hole 16 and the opening 8 of the suction cover 7 when the water level drops M. . As a result, the discharge pressure of the horizontal axis submersible pump 1 decreases, but the operation is continued in a state where water and air are mixed in the casing 2. The amount of water in the casing 2 fluctuates according to the suction side water level. In the idling mode M3, since the submersible motor 6 is cooled by the water stirred in the casing 2, excessive heat generation can be suppressed.

  In the idling mode M3, water and air circulate and flow in the casing 2 and the discharge pressure is low, so the flap gate 9 is basically in a closed state. However, when the water level on the downstream side is lowered, the flap gate 9 may be opened. Further, even if the operation at the rated rotational speed is performed in a closed state in which the flap gate 9 is closed, a large amount of air is mixed, so the water power is low and it is possible to suppress an increase in pump power.

  Here, in the idling mode M3, basically no water is discharged, so there is no drop in the water level on the suction side. However, if the discharge pressure of the horizontal axis submersible pump 1 becomes a pressure sufficient to open the flap gate 9 due to the lowering of the water level on the downstream side, the water level on the suction side decreases due to drainage. When the water level on the suction side drops and becomes lower than the water level L, the horizontal axis submersible pump 1 stops the operation, judging that the possibility of redraining is low, though it depends on the predicted inflow amount on the suction side. The operation stop timing of the horizontal axis submersible pump 1 may be judged after a control device (not shown) detects a state where the water level below the water level L has continued for a certain period of time by a known water level gauge or the like. The determination may be made automatically based on a preset start time or the like without detecting the water level L.

  On the other hand, when the inflow amount on the upstream side increases during any of the operation modes and the water level rises, the operation mode shifts to another operation mode. For example, it is assumed that the water level rises below the water level L and the water level on the suction side exceeds the water level L. In this case, the operation mode shifts to an idling mode M3 in which water in the casing 2 is agitated with the flap gate 9 closed while taking in water and air from the opening 8 and air from the intake hole 16. . In addition, when the water level rises during idling mode M3 and the water level on the suction side exceeds water level M, the operation mode will be water / water mixing in which water is taken from opening 8 and air is taken in from suction hole 16 Shift to discharge mode M2. Furthermore, when the water level rises in the air / water mixed discharge mode M2 and the water level on the suction side exceeds the water level H, the operation mode shifts to the total drainage mode M1 in which water is sucked from the opening 8 and the intake holes 16.

  In addition, the horizontal axis submersible pump 1 judges the resumption of operation as appropriate according to the inflow predicted amount on the suction side and the specifications of the drainage station or the horizontal axis submersible pump 1 after the operation is stopped. The timing of restarting operation may be any water level on the suction side.

  The horizontal axis submersible pump 1 further includes an air venting mechanism. FIG. 10 is a schematic view showing the configuration of the air extracting mechanism 23 installed in the horizontal axis submersible pump 1. For example, when the water level rises and the operation mode shifts from the air-water mixing and discharging mode M2 to the total water draining mode M1, the air accumulated in the casing 2 is discharged to the outside by the air venting mechanism 23 . The air removal mechanism 23 is, for example, a flap type gate having a small opening, which can be installed above a flap gate 9 attached to the discharge side of the horizontal axis submersible pump 1. When the internal pressure reaches a predetermined pressure as the water content in the casing 2 increases, the flap gate opens and the air in the casing 2 is discharged to the outside. The air removal mechanism 23 only needs to have a mechanism that operates automatically when the internal pressure reaches a predetermined pressure as the water content in the casing 2 increases. The air removal valve etc. which are installed may be sufficient.

  Next, the operation and effects of the horizontal axis submersible pump 1 will be described. As described above, since the horizontal axis submersible pump 1 has the second suction opening (intake unit 14 etc.) opened at a position higher than the upper end of the first suction opening (opening 8), the change in water level on the suction side The operation mode can be switched automatically according to Specifically, when the water level on the suction side is higher than the upper end of the second suction opening, the horizontal axis submersible pump 1 operates the whole amount drainage mode by immersing the first and second suction openings. When the water level on the suction side of the horizontal axis submersible pump 1 is lower than the upper end of the second suction opening and higher than the upper end of the first suction opening, the second suction is performed while sucking water from the first suction opening. Operate in the air-water mixed drainage mode that sucks in air from the opening. Furthermore, when the water level on the suction side is lower than the upper end of the first suction opening, the horizontal axis submersible pump 1 operates in an idling mode that sucks in air from the first and second suction openings and circulates water in the casing. Do.

  For example, when the water level on the suction side drops rapidly, the total drainage mode is switched to the air / water mixed drainage mode, or the air / water mixed drainage mode is switched to the idling mode. Thereby, the horizontal axis submersible pump 1 can suppress the rate of decrease of the water level on the suction side while maintaining the operation at the rated rotational speed of the submersible motor 6 that drives the impeller 3. Further, for example, when the water level on the suction side rises rapidly, the mode is switched from the idling mode to the air-water mixed drainage mode, or from the air-water mixed drainage mode to the total water drainage mode. Thereby, the horizontal axis submersible pump 1 can suppress the rising speed of the water level on the suction side while maintaining the operation of the submersible motor 6 at the rated rotational speed. Therefore, the ON / OFF repetition frequency of the submersible motor 6 or the pump can be reduced.

  Further, in each operation mode of air-water mixed drainage mode and idling mode in which the impeller 3 is not completely submerged, since the operation is performed while sucking in air, no large negative pressure is applied to the impeller 3, and from the water surface Air suction vortex can be suppressed.

  Furthermore, the horizontal axis submersible pump 1 can realize the transition between the operation modes according to the water level without providing a complicated control device or the like.

  Moreover, according to the suction cover 7 as shown in FIG. 2, generation | occurrence | production of the air suction eddy from a water surface can be suppressed, and a vibration and noise can be suppressed. Moreover, in the air-water mixed drainage mode, for example, the intake area at the second suction opening is expanded along with the decrease of the water level on the suction side, so the air suction amount is suitably increased, and the operation modes are smoothed. Can be transferred to

  Furthermore, according to the suction cover 7 as shown in FIG. 3 or FIG. 4, since the suction hole 16 or the suction portion 14 is provided in the front wall 15, air flows uniformly along the front edge 13. Therefore, rapid air inflow can be suppressed, and vibration and noise can be suppressed. Further, by providing the intake holes 16 and the like in the front wall 15, adjustment of the inflowing air amount is facilitated, and inflow of foreign matter can be suppressed.

  As described above, according to the present embodiment, even when the water level on the suction side is less than or equal to the water level at the time of total drainage operation, operation at the rated rotational speed can be maintained, and repetition of stop and start of the pump can be suppressed. A horizontal axis submersible pump can be provided.

Second Embodiment
Next, a horizontal axis submersible pump according to a second embodiment of the present invention will be described. In the horizontal axis submersible pump according to the present embodiment, the shape of the suction cover 7 is different from that of the horizontal axis submersible pump 1 according to the first embodiment. Hereinafter, the same parts as those of the horizontal-axis submersible pump 1 according to the first embodiment will be described with the same reference numerals.

  FIG. 11 is a three-sided view showing the shape of the suction cover 7 in the present embodiment. Compared with the suction cover 7 in the first embodiment shown in FIG. 2, although the overall shape of the suction cover 7 is substantially the same, the shape and formation position of the suction portion 14 are different.

  FIG. 12 is a plan view showing the shape of the intake portion 14 provided on the upper wall 10 as an example of the second suction opening in the present embodiment. The intake portion 14 is an opening which is formed from the start end 14a located near the flange 12 with a predetermined width toward the end end 14b located near the front edge 13 and penetrates the surface and the back surface of the upper wall 10 Air can flow in. In addition, in order to reduce stress concentration due to the opening of the intake portion 14, each corner may be formed in an arc shape. When the intake section 14 is submerged, water is also absorbed from the intake section 14, and when the water level drops, air gradually flows into the suction cover 7 from the side of the start end 14 a of the intake section 14. In particular, in the present embodiment, the width is gradually increased on the front edge 13 side (end 14b side of the intake portion 14) of the upper wall 10 so that the opening area increases from the start end 14a to the end 14b when the water level decreases. As a result, the operation mode can be shifted smoothly as the water level falls. Further, the start end 14a and the end 14b of the intake section 14 and the width thereof are appropriately determined from the conditions such as the inclination angle of the upper wall 10 and the diameter of the pump.

  FIG. 13 is a plan view showing the shapes of a plurality of intake holes 30 provided in the upper wall 10 as another example of the second suction opening in the present embodiment. The formation conditions of the plurality of intake holes 30 satisfy the same conditions as those of the intake unit 14 shown in FIG. Further, the hole diameter of the intake hole 30 and the like are also appropriately determined in accordance with the operating condition of the pump.

  FIG. 14A is a plan view showing the shapes of a plurality of slits 32 provided in the upper wall 10 as another example of the second suction opening in the present embodiment, and the shape of one slit 32 is a triangle, and An example in which a plurality of such slits 32 are arranged in a direction parallel to the main axis 4 is shown. On the other hand, FIG. 14B shows an example in which the shape of one slit 32 is rectangular and a plurality of such slits 32 are arranged in the direction perpendicular to the main axis 4. The conditions for forming the plurality of slits 32 also satisfy the same conditions as those of the intake unit 14 shown in FIG. In addition, the width and the like of the slits 32 are appropriately determined in accordance with the operating conditions of the pump. As shown in FIGS. 13 and 14, by forming the portion corresponding to the intake portion 14 with a plurality of openings, the strength of the upper wall 10 of the suction cover 7 can be maintained, and the suction cover 7 is formed of a thin plate be able to.

  FIG. 15 is a side view showing the shape of the intake portion 14 provided on the side wall 11 as another example of the second suction opening in the present embodiment. The intake section 14 is formed so that the width toward the suction side gradually becomes wider from the start end 14a located at the upper part (direction in which the water level rises) to the end 14b located in the lower part (direction where the water level decreases) , And an opening that penetrates the front surface and the back surface of the side wall 11, and water and air can flow therein. In addition, in order to reduce stress concentration due to the opening of the intake portion 14, each corner may be formed in an arc shape. When the intake section 14 is submerged, water is also absorbed from the intake section 14, and when the water level drops, air gradually flows into the suction cover 7 from the side of the start end 14 a of the intake section 14. Also in this case, by gradually increasing the width on the lower side of the side wall 11 so that the opening area increases from the start end 14a to the end end 14b when the water level drops, the operation mode smoothly transitions with the water level drop. Can. The intake portion 14 formed in the side wall 11 may be, as in the case of being formed in the upper wall 10, a large number of intake holes 30, a plurality of slits 32, and the like.

  FIG. 16 is a diagram for explaining the operation mode of the horizontal axis submersible pump 1 in the present embodiment. In addition, in FIG. 16, although it demonstrates that the shape of the suction cover 7 is what is shown in FIG. 12, it is the same even if it is the suction cover 7 shown to FIGS. 13-15. The horizontal axis submersible pump 1 has three operation modes based on two suction water levels H and M (H> M) set in advance: total water drainage mode M1, air / water mixing discharge mode M2, and idling mode M3. The point which it has is similar to 1st execution form. In this case, the water level H is set at the position of the start end 14 a of the suction portion 14 of the suction cover 7. The water level M is set at the top of the leading edge 13. Further, the water level L is set to the upper limit of the water level where sufficient water can not be supplied to the submersible motor 6 even when the impeller 3 is rotating.

  FIG. 17 is a view for explaining the operation of the horizontal-axis submersible pump 1 in the present embodiment when the operation mode is the total drainage mode M1 (suction side water level> water level H). In the total discharge mode M1, the horizontal axis submersible pump 1 operates in the same manner as the total discharge mode M1 in the first embodiment shown in FIG.

  FIG. 18 is a view for explaining the operation of the horizontal axis submersible pump 1 in the present embodiment when the operation mode is the air / water mixture discharge mode M2 (water level HHsuction side water level> water level M). In the air-water mixture discharge mode M2, the horizontal-axis submersible pump 1 operates in the same manner as the air-water mixture discharge mode M2 in the first embodiment shown in FIG.

  FIG. 19 is a diagram for explaining the operation of the horizontal axis submerged pump 1 in the present embodiment when the operation mode is the idling mode M3 (water level M ≧ suction side water level> water level L). In the idling mode M3, the horizontal axis submersible pump 1 operates in the same manner as the idling mode M3 in the first embodiment shown in FIG.

  Thus, according to this embodiment, the same effect as that of the first embodiment can be obtained.

Third Embodiment
Next, a horizontal axis submersible pump according to a third embodiment of the present invention will be described. In the horizontal axis submersible pump according to the present embodiment, the horizontal axis submersible pump according to the first and second embodiments is that the intake portion 14 as the second suction opening is formed not in the suction cover 7 but in the casing 2. Different from 1. Hereinafter, the same parts as those of the horizontal-axis submersible pump 1 according to the first embodiment will be described with the same reference numerals.

  FIG. 20 is a side sectional view showing the outer shape of a horizontal axis submersible pump 1 according to the present embodiment. In this case, the overall shape of the suction cover 7 is substantially the same as that of the suction cover 7 in the first embodiment shown in FIG. 2, but the suction cover 14 in the present embodiment does not have the suction part. On the other hand, on the upper half of the side surface of the casing 2 and on the upstream side of the installation position of the impeller 3, an intake portion 14 formed of a plurality of intake holes penetrating the outside and the inside of the casing 2 is formed. ing. A plurality of intake holes are formed from the starting end 14a near the top of the cylindrical casing 2 to the end 14b near the center of the cylinder width of the casing 2 along the circumferential direction. In this case, the start end 14a is the intake hole located at the highest water level, and the end 14b is the intake hole located at the lowest water level. In the example shown in FIG. 20, the plurality of intake holes are arranged in the same quantity (the same opening area) from the start end 14a to the end end 14b. Also here, when the intake section 14 is submerged, water is also absorbed from the intake section 14, and when the water level is lowered, air gradually flows into the suction cover 7 from the side of the start end 14a of the intake section 14. .

  FIG. 21 is a plan view showing another outer shape of the horizontal axis submersible pump 1 according to the present embodiment. As shown in FIG. 21, the number of intake holes is increased so that the opening area increases from the start end 14a toward the end end 14b when the water level drops, as shown in FIG. 21. Thus, it is possible to shift the operation mode smoothly as the water level falls.

  In addition, the shape of the some intake hole which comprises the intake part 14 may not be circular, for example, may be slit shape, and can be selected suitably. Further, the hole diameter of the intake hole, the width of the slit, and the like are appropriately determined according to the operating conditions of the horizontal axis submersible pump 1. Furthermore, the start end 14 a and the end 14 b of the intake unit 14 and the width thereof are appropriately determined according to the operating conditions of the airfield and the horizontal axis submersible pump 1.

  FIG. 22 is a diagram for explaining the operation mode of the horizontal axis submersible pump 1 in the present embodiment. The horizontal axis submersible pump 1 has three operation modes based on two suction water levels H and M (H> M) set in advance: total water drainage mode M1, air / water mixing discharge mode M2, and idling mode M3. The point which it has is the same as that of the 1st and 2nd embodiment. In this case, the water level H is set to the position of the start end 14 a of the intake portion 14 of the casing 2. The water level M is set at the top of the leading edge 13. Further, the water level L is set to the upper limit of the water level where sufficient water can not be supplied to the submersible motor 6 even when the impeller 3 is rotating.

  FIG. 23 is a diagram for explaining the operation of the horizontal axis submersible pump 1 in the present embodiment when the operation mode is the total water drainage mode M1 (suction side water level> water level H). In the total discharge mode M1, the horizontal axis submersible pump 1 operates in the same manner as the total discharge mode M1 in the first embodiment shown in FIG.

  FIG. 24 is a view for explaining the operation of the horizontal axis submersible pump 1 in the present embodiment when the operation mode is the air / water mixture discharge mode M2 (water level HHsuction side water level> water level M). In the air-water mixture discharge mode M2, the horizontal-axis submersible pump 1 operates in the same manner as the air-water mixture discharge mode M2 in the first embodiment shown in FIG.

  FIG. 25 is a view for explaining the operation of the horizontal axis submerged pump 1 in the present embodiment when the operation mode is the idling mode M3 (water level M ≧ suction side water level> water level L). In the idling mode M3, the horizontal axis submersible pump 1 operates in the same manner as the idling mode M3 in the first embodiment shown in FIG.

  Thus, according to this embodiment, the same effect as that of the first embodiment can be obtained.

Fourth Embodiment
Next, a horizontal axis submersible pump according to a fourth embodiment of the present invention will be described. The horizontal axis submersible pump according to the present embodiment includes an intake pipe which is an intake port whose one end is connected to the suction cover 7 or the casing 2 and whose other end is open, and the other inlet port is a second suction opening. Is different from the horizontal axis submersible pump 1 according to the first to third embodiments. Hereinafter, the same parts as those of the horizontal-axis submersible pump 1 according to the first embodiment will be described with the same reference numerals.

  FIG. 26 is a side view showing the outer shape of a horizontal axis submersible pump 1 according to the present embodiment. In this case, although the overall shape of the suction cover 7 is substantially the same as the suction cover 7 in the first embodiment shown in FIG. 2, the suction pipe 7 is connected to the suction cover 7 in the present embodiment. Specifically, for example, one end of the intake pipe 14 is connected to the side wall 11 of the suction cover 7 and communicates with the inside of the suction cover 7. The intake pipe 14 extends upward by a predetermined length and is bent in an inverted U-shape. Then, the other end of the intake pipe 14 is opened downward as the intake port 14 a. According to this configuration, since the air is once sucked upward from the air inlet 14a, the floating matter on the water surface can be prevented from blocking the air inlet 14a and the pipe. Note that the other end may be closed and the intake port 14 a may be provided on the side surface of the intake pipe 14.

  Although the bent pipe direction of the intake pipe 14 is not particularly limited, it is opened above the upper wall 10 of the suction cover 7 in order to suppress damage due to a collision with a float or the like on the water surface. It is desirable to project the protective wall 31 upward from the front edge 13 of the wall 10. Further, the position in the height direction of the intake port 14 a of the intake pipe 14 and the pipe diameter are appropriately determined from operating conditions such as specifications of the machine site and the horizontal axis submersible pump 1.

  FIG. 27 is a side view showing another outer shape of the horizontal axis submersible pump 1 according to the present embodiment. One end of the intake pipe 14 may be connected to the upper wall 10 of the suction cover 7 as shown in FIG.

  FIG. 28 is a side view showing another outer shape of the horizontal axis submersible pump 1 according to the present embodiment. One end of the intake pipe 14 may be connected to the side wall of the casing 2 as shown in FIG. As described above, if one end of the intake pipe 14 is connected to a position at which the upstream side of the impeller 3 of the horizontal axis submersible pump 1 sucks air, the position, shape, etc. of the intake pipe 14 are not limited.

  FIG. 29 is a diagram for explaining the operation mode of the horizontal axis submersible pump 1 in the present embodiment. The horizontal axis submersible pump 1 has three operation modes based on two suction water levels H and M (H> M) set in advance: total water drainage mode M1, air / water mixing discharge mode M2, and idling mode M3. The point which it has is the same as that of the 1st-3rd embodiment. In this case, the water level H is set to the position of the intake port 14 a of the intake pipe 14. The water level M is set at the top of the leading edge 13. Further, the water level L is set to the upper limit of the water level where sufficient water can not be supplied to the submersible motor 6 even when the impeller 3 is rotating.

  FIG. 30 is a diagram for explaining the operation of the horizontal axis submersible pump 1 in the present embodiment when the operation mode is the total water drainage mode M1 (suction side water level> water level H). In the total discharge mode M1, the horizontal axis submersible pump 1 operates in the same manner as the total discharge mode M1 in the first embodiment shown in FIG.

  FIG. 31 is a view for explaining the operation of the horizontal-axis submersible pump 1 in the present embodiment when the operation mode is the air-water mixture discharge mode M2 (water level H 吸 込 suction side water level> water level M). In the air-water mixture discharge mode M2, the horizontal-axis submersible pump 1 operates in the same manner as the air-water mixture discharge mode M2 in the first embodiment shown in FIG.

  FIG. 32 is a diagram for explaining the operation of the horizontal axis submerged pump 1 in the present embodiment when the operation mode is the idling mode M3 (water level M ≧ suction side water level> water level L). In the idling mode M3, the horizontal axis submersible pump 1 operates in the same manner as the idling mode M3 in the first embodiment shown in FIG.

  Thus, according to this embodiment, the same effect as that of the first embodiment can be obtained.

Fifth Embodiment
Next, a horizontal axis submersible pump according to a fifth embodiment of the present invention will be described. The horizontal axis submersible pump according to the present embodiment is the same as the fourth embodiment in that it includes an intake pipe which is an intake port having one end connected to the suction cover 7 or the casing 2 and the other end open. In addition, the feature of the horizontal axis submersible pump according to the present embodiment is that the second intake opening is not used for water level determination for determining the operation mode. Hereinafter, the same parts as those of the horizontal-axis submersible pump 1 according to the first embodiment will be described with the same reference numerals.

  FIG. 33 is a side view showing the outer shape of a horizontal axis submersible pump 1 according to the present embodiment. In this case, although the overall shape of the suction cover 7 is substantially the same as the suction cover 7 in the first embodiment shown in FIG. 2, the suction pipe 7 is connected to the suction cover 7 in the present embodiment. Specifically, for example, one end of the intake pipe 14 is connected to the side wall 11 of the suction cover 7 and communicates with the inside of the suction cover 7. The intake pipe 14 extends upward by a predetermined length. Then, the other end of the intake pipe 14 is bent horizontally to be opened as the intake port 14 a. Note that the other end may be closed and the intake port 14 a may be provided on the side surface of the intake pipe 14.

  In the present embodiment, the intake port 14a is positioned above the water level in the air / water mixture discharge mode M2 so that air can be taken in from the air inlet 14a in the air / water mixture discharge mode M2. It is desirable that the intake port 14a be opened above the maximum water level of the water storage tank in order to prevent the floating matter on the water surface from blocking the intake port 14a. Further, a protective wall 31 or the like may be provided as necessary in order to prevent damage due to a collision between the intake pipe 14 and a float or the like on the water surface.

  If one end of the intake pipe 14 is connected to a position where the air is sucked to the upstream side of the impeller 3 of the horizontal axis submersible pump 1, the upper wall 10 of the suction cover 7 or the casing 2 may be connected . The pipe diameter and the like of the intake pipe 14 are appropriately determined from the operating conditions such as the specifications of the machine site and the horizontal axis submersible pump 1.

  Further, the intake pipe 14 is provided with an air amount adjustment mechanism inside. 34A and 34B are schematic views showing the configuration of the air amount adjustment mechanism 33. FIG. The pressure applied to the impeller 3 of the horizontal axis submersible pump 1 fluctuates according to the water level on the upstream side, and the internal pressure of the pump fluctuates. The air amount adjusting mechanism 33 supplies a predetermined amount of air to the horizontal axis submersible pump 1 according to the internal pressure of the pump. As the air amount adjusting mechanism 33, as shown in FIG. 34A, a resistor 33a such as an orifice plate can be used, or as shown in FIG. 34B, a pressure valve 33b that opens and closes with a predetermined pressure as a threshold It can also be used. In the present embodiment, the operation mode of the horizontal axis submersible pump 1 is switched to the air / water mixture discharge mode M2 by introducing a predetermined amount of air when the water level on the suction side decreases. Specifically, when the water level on the suction side decreases, the pressing pressure by the water head decreases, and the upstream side (suction side) of the impeller 3 operating at the rated rotation speed becomes negative pressure. When the negative pressure becomes a negative pressure larger than the resistance value of the air amount adjustment mechanism 33 (or the pressure valve is opened by detection of the set pressure), the air flows into the casing 2 from the intake port 14a opened to the atmosphere. Discharge is performed in a mixed state of air and water. The resistance value, the set pressure, and the like of the air amount adjustment mechanism 33 are appropriately set in accordance with the specifications, operating conditions, and the like of the horizontal axis submerged pump 1.

  FIG. 35 is a diagram for explaining the operation mode of the horizontal axis submersible pump 1 in the present embodiment. The horizontal axis submersible pump 1 has three operation modes based on two suction water levels H and M (H> M) set in advance: total water drainage mode M1, air / water mixing discharge mode M2, and idling mode M3. The point which it has is the same as that of the 1st-4th embodiment. In this case, the water level H is defined in advance as the upper end of the air-water mixture discharge mode M2. Then, the air amount adjustment mechanism 33 is preset to be in the air / water mixture discharge mode M2 when the suction side water level becomes the water level H. The water level M is set at the top of the leading edge 13. Further, the water level L is set to the upper limit of the water level where sufficient water can not be supplied to the submersible motor 6 even when the impeller 3 is rotating.

  FIG. 36 is a diagram for explaining the operation of the horizontal axis submersible pump 1 in the present embodiment when the operation mode is the total water drainage mode M1 (suction side water level> water level H). In the total discharge mode M1, the horizontal axis submersible pump 1 operates in the same manner as the total discharge mode M1 in the first embodiment shown in FIG. However, in the present embodiment, depending on the configuration of the air amount adjusting mechanism 33, all the openings (the air amount adjusting mechanism 33 and the opening 8) communicating with the inside of the horizontal axis submersible pump 1 are not only submerged but all closed. If included, it is included.

  FIG. 37 is a view for explaining the operation of the horizontal-axis submersible pump 1 in the present embodiment when the operation mode is the air-water mixture discharge mode M2 (water level H ≧ suction side water level> water level M). In the air-water mixture discharge mode M2, the horizontal-axis submersible pump 1 operates in the same manner as the air-water mixture discharge mode M2 in the first embodiment shown in FIG. However, in the present embodiment, as described above, the operation mode is set to the air / water mixture discharge mode M2 by setting the air amount adjustment mechanism 33 to a resistance value at which intake starts in the air / water mixture discharge mode M2 upper end water level in advance. Switch.

  FIG. 38 is a view for explaining the operation of the horizontal axis submersible pump 1 in the present embodiment when the operation mode is the idling mode M3 (water level M ≧ suction side water level> water level L). In the idling mode M3, the horizontal axis submersible pump 1 operates in the same manner as the idling mode M3 in the first embodiment shown in FIG.

  Thus, according to this embodiment, the same effect as that of the first embodiment can be obtained.

Sixth Embodiment
Next, a horizontal axis submersible pump according to a sixth embodiment of the present invention will be described. In the conventional horizontal axis submersible pump, it was difficult to cool the submersible motor during operation in the idling mode in which water and air are stirred in the casing when the water level is lowered. On the other hand, in the present embodiment, by matching the water level to the position of the impeller at a predetermined discharge angle θ or more from the lower end of the impeller, water is retained in the casing even during operation in the idling mode The submersible motor is cooled by maintaining the submersion state. Hereinafter, the same parts as those of the horizontal-axis submersible pump 1 according to the first embodiment will be described with the same reference numerals.

  In the following description, for convenience, the horizontal axis submersible pump 1 is in the total drainage mode so that it is easy to understand the position of the front edge 13 of the suction cover 7 and the like with reference to the position of the impeller 3. It has only two operation modes of and an idle mode. However, even in this case, the air-water mixed state exists at the transition between the total drainage mode and the idling mode. However, the air-water mixed state referred to in the present embodiment is different from the operation mode positively provided to obtain each effect of the present invention, such as the air-water mixed discharge mode M2 described in each of the above embodiments. It is a thing. Therefore, the contents of the present embodiment are also applicable to the horizontal-axis submersible pump 1 according to each of the above-described embodiments having three operation modes including the air-water mixing and discharging mode.

  FIG. 39 is a side cross sectional view showing the configuration of a horizontal axis submersible pump 1 according to the present embodiment. The horizontal axis submersible pump 1 according to the present embodiment differs in that the height position A of the front edge 13 of the suction cover 7 is defined based on the position of the impeller 3 as compared to the case of the first embodiment. .

  FIG. 40A is a front view of essential parts of the impeller 3 when one blade of the impeller 3 is viewed from the rotation axis direction. In the figure, the position corresponding to the height position of the front edge 13 of the suction cover 7 is A according to the sign of the height position of the front edge 13 and the position of the boss of the impeller 3 is Ai, and the impeller 3 is The position of the outer end of is Ao. FIG. 40B is a development view of the impeller 3 corresponding to each position shown in FIG. 40A. The discharge angle at position A is θ, the discharge angle at position Ai is θi, and the discharge angle at position Ao is θo. The closer to the center, the larger the ejection angle, and the farther it is from the center (the closer to the outer periphery), the smaller θ, so that θi> θ> θo. Generally, the pressure applied to the fluid discharged at the position where θ is large is high, and the pressure applied to the fluid discharged at the position where θ is small is low.

  When the water level falls on the lower side of the main shaft 4 in the vertical direction, the water and the impeller 3 contact at a position where the discharge angle θ is small, so the pressure applied to the water by the impeller 3 decreases. In particular, when air flows in from the opening 8 of the suction cover 7 and the mixed fluid of water and air is to be discharged, the operation mode changes in accordance with the inflow ratio of water to air.

  When the inflow ratio of water is large, the flap gate 9 supported on the discharge side of the casing 2 is opened and drained by the discharge pressure, but when the inflow ratio of air is large, the discharge pressure is low and the flap gate 9 can not be opened, and water and air are stirred in the casing 2.

  Here, when the water level is at the predetermined discharge angle θ of the impeller 3 on the lower side in the vertical direction of the main shaft 4, the inside of the casing 2 with the flap gate 9 closed at the rated rotational speed. It is possible to maintain the state in which the water is retained to the level at which the submersible motor 6 is submerged. The water level at which the predetermined discharge angle θ is obtained is 10 to 25% above, preferably 10 to 20% above, the impeller diameter ratio from the lower end of the impeller 3.

  When the water level rises and contacts at a position larger than the discharge angle θ of the impeller 3, the flap gate 9 is opened and the water is discharged. On the other hand, when the water level falls and contacts at a position smaller than the discharge angle θ of the impeller 3, the water in the casing 2 can not be maintained to the height at which the submersible motor 6 is submerged.

  FIG. 41 is a three-sided view showing the shape of the suction cover 7 in the present embodiment. The suction cover 7 has an upper wall 10, two side walls 11 extending downward from both side ends of the upper wall 10, and a flange 12 connected to the casing 2. The upper wall 10 is inclined downward toward the suction side (left direction in the side view). The lower ends of the side walls 11 are respectively inclined from both ends of the front edge 13 of the upper wall 10 to the lower vicinity of the casing 2 of the horizontal axis submersible pump 1. The front edge 13 is located to the water level near the lower end of the impeller 3. More specifically, it is desirable to be located 10-25% above the impeller diameter ratio from the lower end of the impeller.

  The opening 8 of the suction cover 7 is a first suction opening in the present embodiment, which is provided in an inclined state such that the suction side is higher than the other side. When the water level drops, air gradually flows into the suction cover 7 from below the front edge 13 located at the top of the opening 8. Since the front edge 13 is located at a height near the lower end of the impeller 3, operation in the total drainage mode is possible until low water level, and noise is suppressed during operation in the idling mode. Water splashing can be suppressed.

  Note that setting the position of the front edge 13 to the water level near the lower end of the impeller 3, specifically, 10% to 25% above the impeller diameter ratio from the lower end of the impeller 3 is as described above. The present invention is applicable to various suction covers 7 adopted in each of the above-described embodiments as well as the embodiment. However, when the suction cover 7 has the front wall 15 as shown in FIG. 3, the position of the front edge 13 mentioned here corresponds to the position of the lower end of the front wall 15. Thereby, in addition to the effect specific to the shape of the suction cover 7 in each embodiment, similarly to the above, the effect that the operation in the total drainage mode is possible until the low water level is also exhibited.

  FIG. 42 is a graph showing the performance curve of the horizontal axis submersible pump 1, in which the horizontal axis represents the flow rate, and the vertical axis represents the lift and power. The specification point flow rate of the total drainage operation at normal time is Q1, and the head is H1. The power is P1 at the time of flow rate Q1. When the water level on the discharge side increases and the back pressure increases, the flow rate decreases and gradually shifts to the left of Q1. At this time, the horizontal axis submersible pump 1 operates in the total amount drainage mode.

  When the water level on the suction side decreases and air flows in from the opening 8 of the suction cover 7, the inside of the casing 2 is mixed with air and water, and the head curve and the power curve are proportionally reduced curves like wavy lines in the graph. It becomes. The reduction ratio fluctuates according to the inflow of air, and the curve decreases as the inflow of air increases.

  When the water level further decreases and the discharge pressure decreases, the horizontal axis submersible pump 1 operates in a state in which the flap gate 9 is closed, that is, operates in the idling mode. The flow rate at this time is zero, and the power is P2. In general, since axial flow vanes increase in power near a flow rate of zero, it is desirable to set to shift to the idling mode at a low water level that sucks as much air as possible. Thereby, the horizontal axis submersible pump 1 can perform the energy saving operation with the power P2 (P2 <P1) lower than the specification point power P1.

  The inflow start of air is determined by the height of the front edge 13 of the suction cover 7 (or the lower end of the front wall 15). When the position of the leading edge 13 is high, air flows in quickly from the opening 8 to be in the air-water mixed state, the head decreases, and the discharge side can not cope with the increase of the water level, and the discharge at the low water level is not possible. Further, the water in the casing 2 is easily scattered from the opening 8 to the suction side during the idling mode when the water level is lowered, and noise due to the stirring in the casing 2 is generated. Therefore, by setting the position of the front edge 13 of the suction cover 7 to a predetermined height, operation is performed in the entire water only drainage mode until the water level drops to the height of the front edge 13, and water on the suction side Can be discharged quickly. In addition, when the water level drops, the idling mode is set according to the start of air inflow, and the operation is continued in a state where water is maintained in the casing 2, so that the submersible motor 6 can be cooled.

  If the height of the front edge 13 is too low, the water in the casing 2 runs short at the start of air inflow, so it is difficult to cool the submersible motor 6. Therefore, in the air-water mixed state, the flow start of air is started below the position where the flap gate 9 does not open, and the water amount higher than that at which the submersible motor 6 can be cooled can be maintained in the casing 2 The front edge 13 of the suction cover 7 is set in the position shown in FIG. Specifically, the height position of the front edge 13 of the suction cover 7 is 10 to 25% above, preferably 10 to 20% above the impeller diameter ratio from the lower end of the impeller 3 as described above.

  FIG. 43 is a view for explaining an operation mode of the horizontal axis submersible pump 1 in the present embodiment. In the present embodiment, unlike the above embodiments, the horizontal axis submersible pump 1 has only two operation modes based on one water level L on the suction side set in advance, only the total drainage mode M1 and the idling mode M3. Have. In this case, the water level L is set to the height position of the leading edge 13.

  FIG. 44 is a diagram for explaining the operation of the horizontal-axis submersible pump 1 in the present embodiment when the operation mode is the total drainage mode M1 (suction side water level> water level L). Also in this total drainage mode M1, the horizontal axis submersible pump 1 operates in the same manner as the total drainage mode M1 in the first embodiment shown in FIG.

  FIG. 45 is a view for explaining the operation of the horizontal axis submersible pump 1 in the present embodiment when the operation mode is the idling mode M3 (water level L ≧ suction side water level). Also in this idling mode M3, the horizontal axis submersible pump 1 operates in the same manner as the idling mode M3 in the first embodiment shown in FIG.

  According to this embodiment, the same effect as that of the first embodiment can be obtained. Specifically, in the present embodiment, by defining the height position of the front edge 13 or the like of the suction cover 7 as described above, the submersible motor 6 can be cooled even during operation in the idling mode. Therefore, the submersible motor 6 can maintain the operation at the rated rotational speed even in the idling mode, and can reduce the repetition frequency of ON / OFF of the submersible motor 6, that is, the pump. Furthermore, the horizontal axis submersible pump 1 according to the present embodiment can adopt three operation modes including the air / water mixed drainage mode M2 by being combined with any of the above embodiments. As a result, the horizontal axis submersible pump 1 according to the present embodiment can also achieve the unique effects of the above embodiments simultaneously.

(Other embodiments)
In each of the above embodiments, a plurality of shapes have been illustrated as to the shape of the suction cover 7, but the present invention is not limited to these. For example, the following modifications are possible.

  First, the upper wall 10 is inclined downward from the discharge side to the suction side in each of the above embodiments, but may be horizontal. On the other hand, the lower end (end edge) of the side wall 11 is also inclined downward from the front edge or the front wall side toward the discharge side in each of the above embodiments, but may be horizontal.

  FIG. 46 is a two-sided view illustrating the shape of the suction cover 7 in which the upper wall 10 is horizontal. On the other hand, FIG. 47 is a two-sided view illustrating the shape of suction cover 7 in which lower end 11a of side wall 11 is horizontal. In addition, it is assumed that the suction cover 7 shown in FIG.46 and FIG.47 each deform | transformed the shape of the suction cover 7 shown in FIG. In particular, even when the upper wall 10 is horizontal as in the suction cover 7 shown in FIG. 46, the first to fifth embodiments can be achieved by forming the suction portion as the second suction opening at any position. The operation mode can be set in the same manner. For example, as shown in FIG. 46, in the case where an intake hole 16 as a second suction opening is formed in the front wall 15 extending downward from the upper wall 10, the suction cover shown in FIG. It can apply similarly to the case where 7 is used.

  Moreover, when the upper wall 10 is horizontal and there is no front wall, the air suction part as a 2nd suction opening may be formed in the upper wall 10 as well. For example, the water level corresponding to the height position of the upper wall 10, that is, the position where the second suction opening is formed is H. In this case, as the operation mode of the horizontal axis submersible pump 1, the total drainage mode M1 when suction side water level> water level H, air / water mixed discharge mode M2 when suction side water level = water level H, water level H> suction At the side water level, the idling mode M3 can be set.

  Further, although the side wall 11 is provided vertically from both end portions of the upper wall 10 in each of the above embodiments, if it is provided extending downward, the side wall 11 is inclined toward the outside or inside of the suction cover 7 For example, it may be rounded outward. Moreover, the both ends of the upper wall 10 here do not represent only a exact end, but the position shifted inside from the both ends is also acceptable.

  Moreover, in the suction cover 7 shown in FIG. 2, although the shape of the front edge 13 of the upper wall 10 which comprises a convex part shall be bow shape, it may be a mountain shape, for example. Moreover, a convex part here is not necessarily restricted to the shape started from the both ends of the front edge 13, and a part of front edge 13 may comprise a convex part. Furthermore, the number of projections may be more than one.

  FIG. 48 is a perspective view illustrating the shape of the suction cover 7 in which a part of the front edge 13 constitutes the convex portion 40. FIG. In this example, the convex portion 40 is formed at the central portion of the front edge 13, and its shape is arcuate. FIG. 49 is a perspective view illustrating another shape of suction cover 7 in which a portion of front edge 13 constitutes convex portion 40. FIG. In this example, the convex portion 40 is formed at the central portion of the front edge 13, but its shape is a mountain shape. FIG. 50 is a perspective view illustrating another shape of the suction cover 7 in which a part of the front edge 13 constitutes the convex portion 40. FIG. In this example, two convex portions 40 are formed on the front edge 13, and the shapes thereof are respectively arcuate. FIG. 51 is a perspective view illustrating another shape of suction cover 7. Other than the shape of the suction cover 7 described above, a combination of the front edge 13 of the upper wall 10 and the front edge 11 b of the side wall 11 can also be regarded as a projection. That is, both ends of the front edge 13 in this case correspond to the lower end of the front edge 11 b.

  In the suction cover 7 shown in FIGS. 3 and 4, the front wall 15 extends downward from the front edge 13 of the upper wall 10, but the front wall 15 does not necessarily extend from the front edge 13. It may not be extended.

  FIG. 52 is a side sectional view illustrating another shape of suction cover 7. The front wall 15 may extend downward from the inside of the upper wall 10 shifted downstream from the front edge 13. Here, it is desirable that the position where the front wall 15 is connected to the inside of the upper wall 10 be a position where the suction resistance that can be generated by the presence of the front wall 15 can be ignored. Therefore, assuming that the distance from the end of the suction cover 7 connected to the casing 2 to the front wall 15 is X and the diameter of the impeller 3 is D, the distance X is D to 1.5 D or more. Is desirable. In the suction cover 7 shown in FIG. 52, both the upper wall 10 and the side wall 11 are considered to be deformed so as to project forward from the position of the front wall 15 in the suction cover 7 shown in FIGS. 3 and 4 It can also be done. In this case, the amount of protrusion of the upper wall 10 and the side wall 11 is not particularly limited as long as the effects described in the above embodiments can be obtained.

  Further, in the suction cover 7 shown in FIG. 4, the intake portion 14 which is the second suction opening is constituted by a plurality of notches, and it is saw-like or wavy as a whole when viewed as a whole. In some cases, it may be composed of notches only. However, from the viewpoint of suppressing noise at the time of intake, it is more advantageous to have a plurality of notches. Also, as to the shape of one notch, various shapes such as an arc shape, a chevron shape or a convex shape may be applied.

  Further, in the suction cover 7 shown in FIG. 4, although the case where the intake portion 14 constituted by a plurality of notches is formed in the front wall 15 is illustrated, it may be formed in the upper wall 10, and further May be formed at the lower end (edge) of the side wall 11.

  FIG. 53 is a perspective view showing the shape of the suction cover 7 provided with a plurality of notches 41 as the intake portion 14 on the upper wall 10. On the other hand, FIG. 54 is a perspective view showing the shape of the suction cover 7 in which a plurality of notches 41 as the intake section 14 are provided at the lower end of the side wall 11.

  Further, in the suction cover 7 shown in FIGS. 3 and 4, the front wall 15 is provided to hang from the front edge 13 of the upper wall 10, but if it is extended downward, it is not always necessary to hang It does not have to be done. For example, the front wall 15 may be extended so as to be inclined toward the inside of the suction cover 7 and may be connected to the upper wall 10 via a curved surface.

  FIG. 55 is a perspective view showing the shape of the suction cover 7 in which the front wall 15 is inclined toward the inside of the suction cover 7 and connected to the upper wall 10 via a curved surface. In addition, it is assumed that the suction cover 7 shown in FIG. 55 deform | transforms the shape of the suction cover 7 shown in FIG. By inclining the front wall 15 toward the inside of the suction cover 7, the opening for the inner space of the suction cover 7 is more than when the front wall 15 having a notch is provided vertically from the front edge 13 of the upper wall 10. Since the opening amount of the portion 8 is narrowed, it is difficult to leak noise to the outside. Therefore, noise can be further suppressed particularly when the operation mode is the idling mode. On the other hand, by making the tip of the suction cover 7 rounded, the debris flowing from the upstream side is less likely to adhere to the tip portion of the suction cover 7.

  In addition, the shapes of the various suction covers 7 described above do not necessarily have to be individually adopted, and may be a shape in which each feature is combined. For example, the suction cover 7 may have both of the two types of air intakes 14 illustrated in FIGS. 53 and 54.

  Next, regarding the entire configuration of the horizontal axis submersible pump 1, in each of the above embodiments, the pump main body is installed parallel to the water surface, that is, horizontally. In addition, the pump main body here is synonymous with the main axis | shaft 4 arrange | positioned in the casing 2, and more specifically, the casing 2. As shown in FIG. However, the present invention is not limited to such a pump in which the pump body is installed horizontally, and is also applicable to a pump in which the pump body is installed to be inclined downward on the suction side.

  Moreover, in each said embodiment, the casing 2 and the suction cover 7 shall be separate bodies. This is advantageous in that the suction cover 7 can be easily replaced with another suction cover 7 when the suction cover 7 is broken or the suction cover 7 is changed to another shape according to the purpose. However, this is not an essential configuration, and the casing 2 and the suction cover 7 may be integrated.

  In each of the above-described embodiments, the impeller 3 is supported so as to be accommodated in the casing 2 as shown in FIG. 1. However, the impeller 3 is extended by extending the main shaft 4 toward the suction cover 7. In some cases, 3 may extend into the suction cover 7.

  Thus, it goes without saying that the present invention includes various embodiments and the like which are not described herein. Accordingly, the technical scope of the present invention is defined only by the invention-specifying matters according to the claims that are appropriate from the above description.

  Japanese Patent Application No. 2015-093983 (filing date: May 1, 2015), Japanese Patent Application No. 2015-093984 (filing date: May 1, 2015), Japanese Patent Application No. 2015-093985 (filing date: May 2015) 1), Japanese Patent Application No. 2015-093986 (filing date: May 1, 2015), Japanese Patent Application No. 2015- 093987 (filing date: May 1, 2015), Japanese Patent Application No. 2015-146260 (filing date: The entire contents of July 24, 2015) are incorporated herein.

1 Horizontal Axis Submersible Pump 2 Casing 3 Impeller 7 Suction Cover 8 Opening 14 Intake

Claims (10)

A casing having an inlet and an outlet;
An impeller supported in the casing;
A suction cover connected to the suction port;
A first suction opening provided at the suction cover and opening at a position lower than the upper end of the impeller;
A second suction opening provided upstream of the impeller in at least one of the suction cover and the casing and opening at a position higher than an upper end of the first suction opening;
Have
The suction cover is
With the upper wall,
A side wall extending downward from the upper wall;
And a front wall extending downward from the upper wall,
The horizontal axis submersible pump whose said 2nd suction opening is a hole which penetrates said front wall. A casing having an inlet and an outlet;
An impeller supported in the casing;
A suction cover connected to the suction port;
A first suction opening provided at the suction cover and opening at a position lower than the upper end of the impeller;
A second suction opening provided upstream of the impeller in at least one of the suction cover and the casing and opening at a position higher than an upper end of the first suction opening;
Have
The suction cover is
With the upper wall,
A side wall extending downward from the upper wall;
And a front wall extending downward from the upper wall,
The first suction opening is an opening surrounded by the lower end of the front wall and the lower end of the side wall,
The second suction opening is an opening that is in communication with the first suction opening and is an opening surrounded by at least one notch formed in the front wall and a straight line connecting the lower end of the front wall. pump. A casing having an inlet and an outlet;
An impeller supported in the casing;
A suction cover connected to the suction port;
A first suction opening provided at the suction cover and opening at a position lower than the upper end of the impeller;
A second suction opening provided upstream of the impeller in at least one of the suction cover and the casing and opening at a position higher than an upper end of the first suction opening;
Have
The suction cover is
With the upper wall,
And a side wall extending downward from the upper wall,
The first suction opening is an opening surrounded by the front edge of the upper wall and the lower end of the side wall,
The second suction opening is in communication with the first suction opening, and is an opening surrounded by at least one notch formed in the upper wall and a straight line connecting the front edge of the upper wall, or A horizontal axis submersible pump, which is an opening that is in communication with a first suction opening and is surrounded by at least one notch formed in the side wall and a straight line connecting a lower end of the side wall. A casing having an inlet and an outlet;
An impeller supported in the casing;
A suction cover connected to the suction port;
A first suction opening provided at the suction cover and opening at a position lower than the upper end of the impeller;
A second suction opening provided upstream of the impeller in at least one of the suction cover and the casing and opening at a position higher than an upper end of the first suction opening;
Have
The suction cover is
With the upper wall,
And a side wall extending downward from the upper wall,
The horizontal axis submersible pump, wherein the second suction opening is an opening formed in the upper wall or the side wall. A casing having an inlet and an outlet;
An impeller supported in the casing;
A suction cover connected to the suction port;
A first suction opening provided at the suction cover and opening at a position lower than the upper end of the impeller;
A second suction opening provided upstream of the impeller in at least one of the suction cover and the casing and opening at a position higher than an upper end of the first suction opening;
An intake pipe which is an intake port having one end connected to the suction cover or the casing and the other end opened;
Have
The suction cover is
With the upper wall,
And a side wall extending downward from the upper wall,
The horizontal axis submersible pump in which the second suction opening is the suction port. A horizontal axis submersible pump according to any one of claims 1 to 5 , wherein
The front edge of the upper wall of the suction cover or the lower end of the front wall extending downward from the upper wall of the suction cover is 10% to 25% in diameter ratio of the impeller from the lower end of the impeller Located at the top. A horizontal axis submersible pump according to any one of claims 1 to 6 , wherein
Furthermore, a flap gate is provided on the side of the discharge port of the casing and can be opened and closed by the pressure of the fluid discharged from the discharge port. A horizontal axis submersible pump according to any one of claims 1 to 7 , wherein
Furthermore, an air venting mechanism is provided for exhausting the air in the casing to the outside when the internal pressure of the casing reaches a predetermined pressure. With the discharge opening,
With the upper wall,
A side wall extending downward from the upper wall;
A front wall extending downward from the upper wall;
A first suction opening surrounded by the lower end of the front wall and the lower end of the side wall;
It has a second suction opening, which is an opening that is in communication with the first suction opening and is surrounded by at least one notch formed in the front wall and a straight line connecting the lower ends of the front wall.
Suction cover used for horizontal axis submersible pump. With the discharge opening,
With the upper wall,
A side wall extending downward from the upper wall;
A first suction opening surrounded by a front edge of the upper wall and a lower end of the side wall;
It communicates with the first suction opening and communicates with the opening surrounded by at least one or more notches formed in the upper wall and a straight line connecting the front edge of the upper wall, or the first suction opening A second suction opening which is an opening surrounded by at least one or more notches formed in the side wall and a straight line connecting lower ends of the side wall;
Suction cover used for horizontal axis submersible pump.

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