JP7629632B2 - Submersible pump with air pipe and its equipment - Google Patents

Description

The present invention relates to an underwater pump with an air pipe and its installation. More specifically, the present invention relates to an underwater pump with an air pipe and its installation, which is fixed to the gate body of a water gate installed across a river or the like, and which maintains operation at the rated speed even when the water level on the suction side is below the minimum water level at which full discharge can be performed, and which makes it possible to suppress repeated starting and stopping of the pump.

When the water level on the suction side of a submersible pump drops below a certain level, air is sucked into the pump casing from the suction, causing the pump to operate in a mixed air-water mode, reducing the amount of discharge and increasing vibration and noise. For this reason, when the water level on the suction side drops below a certain level, the pump is temporarily stopped, and then restarted when the inflow rate increases and the water level on the suction side rises. In such cases, if the pump is frequently turned on and off depending on the water level on the suction side, this is undesirable as it makes operation management cumbersome, the pump needs to be started and stopped more frequently, and puts a heavy burden on the submersible motor and starter.

The pump gate described in Patent Document 1 has a suction cover with a straightening effect installed above the pump suction port, which suppresses the occurrence of air suction vortices and underwater vortices, allowing the pump to operate at lower water levels. The advance standby operation pump described in Patent Document 2 has a compressed air supply passage in the main shaft of the vertical pump to prevent abnormal vibrations and noise when switching from drainage operation to water holding operation. This compressed air supply passage discharges compressed air from the inlet side of the impeller, quickly dropping the remaining water in the discharge pipe into the water supply well, and shortens the water holding operation, which allows full speed operation regardless of the water level of the pump well. Furthermore, the underwater pump described in Patent Document 3 draws air from a notch in the suction cover or from the intake pipe when the water level on the suction port side drops, and performs air-water mixing operation to reduce the amount of water discharged, and maintains operation at the rated speed even if the water level on the suction port side is below the water level during full water discharge operation, suppressing repeated on-off switching of the pump.

JP 2003-3450 A Japanese Patent Application Publication No. 8-312580 WO2016/178387

However, the pump described in Patent Document 1 prevents the continuous generation of air suction vortexes and prevents vibration noise that occurs when air is sucked in, but the pump is repeatedly turned on and off depending on the water level on the suction port side, and does not allow operation at the rated speed even when the water level is below the minimum water level. The pump in the advance standby operation described in Patent Document 2 is a pump with a vertical impeller drive shaft, and is not intended to be a horizontal or inclined shaft. The submersible pump described in Patent Document 3 is a horizontal shaft, and introduces air when the water level falls below a certain level, but vibrations and noise increase during air-water mixed operation, and the discharge volume also decreases. Furthermore, if the water level further decreases, if the pump is operated at the rated speed while the discharge volume is lost, it will switch from air-water mixed operation to air standby operation, but it is better to keep this air-water mixed operation as short as possible, or to not actually occur at all.
The present invention has been made against the above background and has the following objectives.
An object of the present invention is to provide an air pipe-equipped submersible pump and its equipment that uses an air on-off valve to prevent air-water mixed operation.
Another object of the present invention is to provide an underwater pump with an air pipe and its equipment which maintains operation at the rated speed even when the water level on the suction side is below the minimum water level at which full drainage is possible, thereby suppressing repeated starting and stopping of the pump.

In order to solve the above problems, the present invention takes the following measures.
That is, the submersible pump with air pipe of the present invention 1 is as follows:
a casing having a suction port on one side and a discharge port on the other side;
an electric motor fixed within the casing for rotating and driving the device;
an impeller coupled to the output shaft of the electric motor, the output shaft being disposed in a lateral direction in which the axis of the output shaft is horizontal, or the axis of the output shaft being inclined at a predetermined angle from the horizontal, and being rotated;
a suction cover fixed to the casing and having an opening for sucking in a fluid,
an air pipe for drawing air into the submersible pump from a discharge port disposed upstream of the impeller and within the submersible pump;
an air on-off valve for supplying or blocking air to the air pipe ;
A water level meter that detects the water level on the suction port side;
an on-off valve control means for controlling the opening and closing of the air on-off valve based on a water level detection value of the water level gauge ;
The discharge port of the air pipe is disposed opposite the impeller, and a central axis of the discharge port is parallel to the axis of the impeller.
The central axis of the discharge port is disposed at a position lower than the axis of the output shaft .

The submersible pump with an air pipe of the second aspect of the present invention is characterized in that, in the submersible pump with an air pipe of the first aspect of the present invention, the submersible pump with an air pipe is a submersible mixed flow pump in which the flow path of the fluid driven by the impeller is inclined with respect to the axis, or a submersible axial flow pump in which the flow path of the fluid is in the direction of the axis.
The submersible pump with an air pipe of the third aspect of the present invention is characterized in that, in the submersible pump with an air pipe of the first or second aspect of the present invention, the on-off valve control means controls the water level when opening and closing the air on-off valve differently when the water level is rising and when the water level is falling.

The submersible pump with an air pipe of the fourth aspect of the present invention is the submersible pump with an air pipe of the first or second aspect of the present invention, characterized in that the air pipe is connected to the suction cover or the casing.
The submersible pump equipment with an air pipe of the fifth aspect of the present invention is a submersible pump equipment using the submersible pump with an air pipe of any one of the first to fourth aspects of the present invention, characterized in that the submersible pump with an air pipe is mounted on a sluice gate or a culvert that crosses a river or waterway.

The submersible pump with air pipe and the equipment thereof of the present invention supplies air from the air pipe when the water level on the suction side falls below the minimum water level required for full drainage operation, allowing instantaneous transition from full drainage operation to air standby operation. If the water level on the suction side rises during air standby operation, the air is cut off, allowing instantaneous transition from air standby operation to full drainage operation. As a result, air-water mixing operation is terminated in a short time or is eliminated entirely, making it possible to maintain operation at the rated speed while reducing vibration and suppressing repeated starting and stopping of the pump.

FIG. 1 is a vertical cross-sectional view showing a submersible mixed-flow pump 1 equipped with an air supply circuit 60 according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram showing an overview of an air supply circuit 60 for supplying or cutting off air to the submersible mixed-flow pump 1 according to the first embodiment of the present invention. FIG. 3 is a flow chart showing an example of the operation of the motor-operated valve control circuit 71 for supplying or cutting off air to the submersible mixed-flow pump 1 of the first embodiment of the present invention. FIG. 4 is a graph showing the current and vibration of the submersible mixed-flow pump 1 of the first embodiment of the present invention when the water level on the suction port side is increased and decreased. FIG. 5 is a graph showing the current and vibration of a conventional submersible mixed-flow pump when the water level on the suction port side is increased or decreased. FIG. 6 is a vertical cross-sectional view showing a submersible axial flow pump 10 equipped with an air supply circuit 60 according to a second embodiment of the present invention.

[Submersible mixed flow pump 1 according to the first embodiment]
A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross-sectional view of a submersible mixed-flow pump 1 according to a first embodiment of the present invention. As shown in FIG. 1, the submersible mixed-flow pump 1 according to the first embodiment of the present invention is fixed to a gate body 100 of a water gate or a culvert installed across a river, a waterway, a sewerage channel, etc., via a bracket 101 or the like and bolts or the like. It is also possible to use a structure in which the flange portion of the casing 2 of the submersible mixed-flow pump 1 is directly fixed to the gate body 100 of the water gate or the culvert. These structures are structures in which a submersible pump is mounted on a water gate (gate) to integrate the two, and are called a gate pump (trademark registration No. 2585973, commonly known as a "pump gate").

The submersible mixed flow pump 1 of this embodiment is called a mixed flow pump in which the flow of fluid discharged from the impeller is diagonal from the center line of the output shaft 31. The submersible mixed flow pump 1 has a casing 2 with a suction port 21 on one side (left side of FIG. 1) and a discharge port 22 on the other side (right side of FIG. 1). Inside the casing 2, an electric motor 3 for rotating and driving the impeller 32 is fixed. An output shaft 31 is attached to the electric motor 3 of the submersible mixed flow pump 1 on the suction port 21 side, the impeller 32 is fixed to the output shaft 31, and the rotational torque of the electric motor 3 is transmitted to the impeller 32. A guide vane 33 is fixed adjacent to the downstream side of the impeller 32 between the inner circumference of the casing 2 and the outer circumference of the oil chamber 34. The guide vane 33 guides the water pumped by the impeller 32.

A flap valve 4 that is supported so as to be able to open and close is disposed on the discharge port 22 side of the casing 2. This flap valve 4 is attached so as to be able to swing freely at a fulcrum 4a disposed at the top of the casing 2. When the water discharge pressure from the discharge port 22 is low, the flap valve 4 closes under its own weight, and when the water discharge pressure increases, it opens around the upper fulcrum 4a, allowing water to be discharged from the discharge port 22. A suction cover 5 is fixed to the suction port 21 of the casing 2 to smoothly guide water to the suction port 21. An opening 53 at the tip of the suction cover 5 faces diagonally downward from the horizontal (angle of attack θ), and upstream river water is sucked in through this opening 53.

As shown in FIG. 1, the submersible mixed-flow pump 1 has the axis 311 of the output shaft 31 arranged horizontally. If the height from the bottom surface 102 of the waterway to the upper edge (the lower surface of the suction guide plate 511) 531 of the opening 53 of the suction cover 5 is Y1, and the height from the bottom surface 102 of the waterway to the lower end of the impeller 32 is Y3, then Y1 is arranged at a position higher than Y3. The upper edge 531 of the opening 53 of the suction cover 5 is arranged at a position lower than the axis 311 of the output shaft 31 of the motor 3. The lower edge 532 of the opening 53 is at a height of Y2 from the bottom surface 102 of the waterway. When the water level is equal to or lower than the water level Y2 of the lower edge 532 of the opening 53, the position is lower than the height Y3 to the lower end of the impeller 32, so the submersible mixed-flow pump 1 does not suck in river water. The water level shown on the left in FIG. 1 indicates the boundary between the water level at which full drainage is possible when the water level is falling or rising, and the standby operation water level (air standby operation) when operating the submersible mixed-flow pump 1 of the first embodiment of the present invention.

Air supply circuit 60
2 is a block diagram showing an outline of an air supply circuit 60 for supplying or cutting off air to the submersible mixed-flow pump 1. The air supply circuit 60 includes a water level gauge 70, an electric valve control circuit 71, an electric air valve 63, an air pipe 64, and an outlet 65. Air, which is the atmosphere, passes through the electric air valve 63 and the air pipe 64 and is sucked into the casing 2 from the outlet 65 by the suction force (negative pressure) during operation of the submersible mixed-flow pump 1. The outlet 65 is piped to an air pipe 64 attached to the suction cover 5. The electric air valve 63 is stored in a watertight sealed storage chamber 66 so as not to get wet (see FIG. 1). The central axis of the outlet 65, which is a pipe, is arranged parallel to the axis 311 of the output shaft 31 of the submersible mixed-flow pump 1. More precisely, the central axis of the outlet 65 is arranged at a position lower than the axis 311 of the output shaft 31. That is, the discharge port 65 is disposed opposite the impeller 32 and at a position lower than the axis 311 .

For this reason, the air sucked in from the discharge port 65 is sucked in toward the center of the impeller 32 and above and below the impeller 32 almost uniformly while moving slightly upward due to the buoyancy of the air. The timing of opening and closing the electric air valve 63 is controlled by the electric valve control circuit 71. The water level gauge 70 constantly measures the water level of the upstream river, measuring the water level by water pressure, etc. This structure and function are well known technology and will not be described. The electric valve control circuit 71 controls the opening and closing of the electric air valve 63 while watching the water level of the water level gauge 70 when the submersible mixed flow pump 1 is operating. The opening and closing control of the electric air valve 63 is performed according to the water level detected by the water level gauge 70. In FIG. 1, the leftmost part shows the water level at which the electric air valve 63 is opened when switching from full discharge operation to air standby operation when the water level drops. To the right of this, the water level at which the electric air valve 63 is closed when switching from air standby operation to full discharge operation when the water level rises is shown.

The reason why the water level positions for opening and closing the motorized air valve 63 are different when the water level is falling and rising is as follows. That is, in order to avoid air-water mixed operation when the water level is rising and falling, "When the water level is falling, if the water level is near the upper edge 531 of the opening 53 of the suction cover 5, the casing 2 is full of water and full-volume drainage operation is performed, and when the water level falls below the upper edge 531, air is sucked in from the suction cover 5. The motorized air valve 63 is opened at the "air valve opening water level" (in this embodiment, a water level about 10 mm higher than the upper edge 531) which is the water level near the upper edge 531, air is sucked into the casing 2 from the air pipe 64, the water in the casing 2 is drained in one go, and the operation is instantly switched from full-volume drainage operation to air standby operation. " Also, "When the water level is rising, when the water level reaches 60% or more of the height of the impeller 32, the impeller 32 can discharge the water in the casing 2 by itself. In order to reliably avoid air-water mixed operation at this water level when the water level rises, the motorized air valve 63 is closed at the "air valve closing water level" (in this embodiment, a water level of about 55% of the impeller 32), which is a water level slightly lower than that water level, and air from the air pipe 64 is cut off. When the water level reaches a water level at which full drain operation is possible (about 60% of the impeller 32), the operation instantly shifts from air standby operation to full drain operation. For the above reasons, the water level positions at which the motorized air valve 63 opens and closes are different when the water level is falling and rising.

Operation of the air supply circuit 60 FIG . 3 is a flow diagram showing an example of the operation of the motor-operated valve control circuit 71 of the air supply circuit 60. This flow diagram is a control example when the "air valve opening water level" and "air valve closing water level" of the motor-operated air valve 63 are set to the positions shown in FIG. 1. The power supply to the motor 3 (FIG. 1) is turned on (S1). The timer counter that sets the operation time of the motor 3 is set to zero, and the valve of the motor-operated air valve 63, which is in a state of cutting off air, is closed (S2, S3). When the operation of this control device starts, the control is in a full-volume drainage operation state. Next, the water level gauge 70 measures the water level on the intake side to obtain water level data (S4). It is determined whether this water level data is "above the air valve closing water level" (see FIG. 1) or not (S5).

In S3, the motorized air valve 63 is closed, and in S5, if the water level is "above the air valve closing water level" (YES), that is, this water level is not in air standby operation but is in the full-drain operation range (see FIG. 1). In this case (YES), it is determined whether "motorized air valve 63: closed?" (S12). If the motorized air valve 63 is closed (YES), full-drain operation is possible, the timer counter is set to zero (S14), and the process returns to "water level measurement" (S4) to continue full-drain operation. If the motorized air valve 63 is not closed (NO), the motorized air valve 63 is closed (S13), the timer counter is set to zero (S14), and the process similarly returns to "water level measurement" (S4) to continue full-drain operation.

In S5, if the water level is not "above the air valve closing water level?" (NO), it is further determined whether the water level is "below the air valve opening water level?" (S6). In S6, if the water level is "below the air valve opening water level" (YES), the water level at this time means that the water level is in the air standby operation range regardless of whether the water level is "falling" or "rising" (see FIG. 1). If it is determined to be in this air standby operation range (YES), the electric air valve 63 must be open, so proceed to the next step S7 to confirm whether "electric air valve 63: open?" is determined (S7). If the electric air valve 63 is already open (YES), proceed to step S9. If the electric air valve 63 is closed (NO), it is in the air standby operation range, so the electric air valve 63 is opened and the operating time for air standby operation of the electric motor 3 is set (S8, S9). This operating time setting is for the low water level area, and since there is no need to continue air standby operation any longer than necessary, it sets the operating time of the motor 3. In S10, it is determined whether the time that the system transitioned to air standby operation is "longer than the operating time."

If the operation time of the motor 3 is not equal to or greater than the set time (NO), the process returns to step S4, i.e., the air standby operation continues. If the operation time of the motor 3 is equal to or greater than the set time (YES), the power supply to the motor 3 is turned off (step S11). That is, the operation of the submersible mixed-flow pump 1 is stopped because the set operation time has reached the set time. On the other hand, if the water level is not "air valve opening water level or lower?" in S6 (NO), the process proceeds to S15. The water level at this time is neither "air valve closing water level or higher?" (S5) nor "air valve opening water level or lower?" (S6), so the water level at this time means an intermediate water level between the "air valve opening water level" and the "air valve closing water level" (see Figure 1). This intermediate water level is a setting range in which the motor air valve 63 is opened when the water level rises and closed when the water level falls.

In this step S15, if the motor air valve 63 is open (YES), it means that the water level is rising. In the "water level rising" state, the water level region that is the intermediate water level is the air standby operation region. The motor air valve 63 is left open, and the process jumps to S9 to continue the air standby operation until the set time. In other words, at this intermediate water level, the fact that the motor air valve 63 is already open usually means that the water level is rising, and at this water level, it means the air standby operation water level. For this reason, the motor air valve 63 remains open. Then, the process jumps to S4, and the operation of the electric motor 3 continues. In this step S15, if the motor air valve 63 is not open (NO), it means that the water level is falling. The process continues with the motor air valve 63 closed. In other words, when the electric air valve 63 is not open at this intermediate water level, it means that the water level is falling and the area is in the full drain operation range, and with the electric air valve 63 closed, the timer counter is set to zero (S16), and the system returns to the "water level gauge side" (S4) and continues the full drain operation.

The above operations can be summarized as follows. For example, when an operator turns on the motor 3 of the submersible mixed flow pump 1 by turning on the switch (not shown), the motor 3 starts rotating and pumps up the river water from the upstream side and flows it downstream. The motor valve control circuit 71 judges the current water level based on the water level signal from the water level gauge 70, controls the opening and closing of the motor air valve 63, and selects full discharge operation or air standby operation. Then, the timing of opening and closing the motor air valve 63 is changed depending on whether the water level is rising or falling. Even if the water level on the suction port side drops during full discharge operation while the water level is falling, as shown in Figure 1, if the water level on the suction port side is higher than the "air valve opening water level", air is not sucked in from the opening 53, so that the suction cover 5 and the casing 2 are filled with water. Therefore, the submersible mixed flow pump 1 continues to operate in full discharge operation at the rated speed. When the water level drops from the full discharge operation water level, the motor-operated valve control circuit 71 opens the motor-operated air valve 63 when it reaches the "air valve open water level" position, and supplies air to the submersible mixed-flow pump 1 via the air pipe 64. This air supply causes the submersible mixed-flow pump 1 to immediately enter the air standby operation mode.

When the water level rises from the air standby operation, the motor valve control circuit 71 closes the motor air valve 63 when it reaches the "air valve closing water level" position, and cuts off the air to the submersible mixed flow pump 1 through the air pipe 64. In this embodiment, when the water level reaches 60% or more of the impeller 32, the impeller is in a state where it can discharge the water in the casing 2 by itself, so the submersible mixed flow pump 1 goes from the air standby operation mode to the full discharge operation mode in one go. Also, even if the water level on the suction port side drops during the full discharge operation while the water level is rising, as shown in FIG. 1, the motor air valve 63 is closed when the water level on the suction port side is at the "air valve closing water level", so if the water level is higher than this water level, air is not sucked in from the opening 53, and the suction cover 5 and the casing 2 are filled with water. Therefore, the submersible mixed flow pump 1 continues to operate in full discharge operation at the rated speed. The "air valve opening water level" and "air valve closing water level" will differ depending on the natural conditions, or more precisely, the on-site conditions, where the pump (submersible mixed flow pump 1) is installed, so it is a good idea to operate the pump in the river where it will actually be installed and use the results to determine the optimal water level.

When the water level on the suction port side falls below the "air valve opening water level" in FIG. 1, air is sucked in through the opening 53. Before air is sucked in through this opening 53, the electric air valve 63 is opened and air is supplied through the air pipe 64. As a result, the water in the suction cover 5 and the casing 2 of the submersible mixed flow pump 1 instantly falls, and the impeller 32 cannot discharge water, so the pressure inside the pump drops, the flap valve 4 closes due to its own weight and the pressure of the outside water, and the impeller 32 is exposed to the air and enters air standby operation (the motor 3 continues to rotate at the rated speed), so there is little vibration and the burden on the motor 3 is small. Even if the water level on the suction port side falls further, the air standby operation continues within a set time (for example, set by a timer not shown). Therefore, the submersible mixed flow pump 1 of the first embodiment of the present invention does not have air-water mixing operation, so there is little vibration. In this embodiment, the submersible mixed flow pump 1 instantly switches from full-flow drainage operation to air standby operation when the water level on the suction port side falls below the minimum water level at which full-flow drainage operation is possible, and if the water level on the suction port side rises during air standby operation and reaches the water level at which full-flow drainage operation is possible (approximately 60% of the water level of the impeller 32), it instantly switches from air standby operation to full-flow drainage operation. As a result, there is no air-water mixing operation, vibration is reduced, and operation at the rated speed can be maintained.

When the water level is below the water level Y2 at the lower edge 532 of the opening 53 of the suction cover 5, it is not possible to physically suck in river water, so there is no need to suck air into the casing 2 from the outlet 65 of the air pipe 64. However, at the water level for air standby operation (see FIG. 1), the air standby operation continues within a set time (set by a timer, not shown) with the electric air valve 63 open. This control makes it possible to suppress repeated starting and stopping of the submersible mixed-flow pump 1. Figure 4 is a graph showing the current (A) and vibration (note: composite vibration in the X, Y, and Z directions) (μm) of the electric motor 3 of the submersible mixed-flow pump (pump diameter 300 mm) 1 of this embodiment of the present invention. In FIG. 4, the water level on the suction port side is raised from 200 mm to 600 mm, and then lowered to 200 mm. As shown in Figure 4, when the water level rises, the system instantly switches from air standby operation to full drain operation, and when the water level falls, the system instantly switches from full drain operation to air standby operation. Since no air-water mixing operation occurs, the fluctuations in current (A) and vibration (μm) are reduced.

Figure 5 is a graph showing the current (A) and vibration (note: composite vibration in the X, Y, and Z directions) (μm) of the motor 3 of a conventional submersible mixed flow pump (pump diameter 300 mm) that does not have an air pipe. As shown in Figure 5, the conventional submersible mixed flow pump draws in air from the upper edge 531 of the opening 53, causing air-water mixing operation, so it takes time to switch from air standby operation to full drain operation and from full drain operation to air standby operation, and the vibration is large. In contrast, the submersible mixed flow pump 1 of the first embodiment of the present invention does not cause air-water mixing operation as shown in Figure 4, so the switch from air standby operation to full drain operation and from full drain operation to air standby operation is instantaneous and the vibration is small.

[Submersible axial flow pump 10 according to the second embodiment]
The submersible axial flow pump 10 of the second embodiment shown in FIG. 6 has a different structure from that of the first embodiment. The submersible axial flow pump 10 is a pump that sends a fluid in the direction of the axis 311 of the output shaft 31, and has a casing 2 having a suction port 21 on one side (left side of FIG. 6) and a discharge port 22 on the other side (right side of FIG. 6). An electric motor 3 for rotating is fixed inside the casing 2. An output shaft 31 is attached to the electric motor 3 on the discharge port 22 side, and an impeller 32 is fixed to the output shaft 31, and the rotation of the electric motor 3 is transmitted to the impeller 32. A guide vane 33 is fixed between the inner circumference of the casing 2 and the outer circumference of the oil chamber 34 on the suction port 21 side (upstream side) of the impeller 32. The guide vane 33 guides the water pumped up by the impeller 32.

The casing 2 is fitted with a flap valve 4 supported so as to be able to open and close on the discharge port 22 side. When the discharge pressure of the water from the discharge port 22 is low, the flap valve 4 closes under its own weight, and when the discharge pressure of the water is high, it opens around the upper fulcrum 4a, allowing the water to be discharged from the discharge port 22. A suction cover 5 is fixed to the suction port 21 of the casing 2 to smoothly guide the water to the suction port 21. As shown in FIG. 6, the suction cover 5 is formed of one or more plates such as an upper plate and a side plate. The submersible axial flow pump 10 of the second embodiment is provided with an air supply circuit 60 that operates on the same principle as the first embodiment described above. It is made up of a water level gauge 70, an electric valve control circuit 71, an electric air valve 63, an air pipe 64, a discharge port 65, etc.

The suction force of the underwater axial flow pump 10 during operation causes the air pipe 64 connected to the electric air valve 63 to branch into two, and the air, which is the atmosphere, is sucked into the casing 2 from the branch pipe (not shown) through two outlets 65. The two outlets 65 are arranged on the left and right sides of the outer periphery of the motor 3, that is, in the suction cover 5 on both sides of the motor 3. These outlets 65 are piped to the air pipe 64 fixed to the suction cover 5. The central axis of the outlet 65 is arranged parallel to the axis 311 of the output shaft 31 of the underwater axial flow pump 10. To be precise, the central axis of the outlet 65 is arranged slightly lower than the axis 311 of the output shaft 31. In other words, the outlet 65 is arranged lower than the axis 311 so as to face the front of the impeller 32. The water level gauge, control circuit, etc. for operating the electric air valve 63 of the submersible axial flow pump 10 of the second embodiment are substantially the same as those of the submersible mixed flow pump 1 of the first embodiment, and their description will be omitted. As shown in the leftmost part of Figure 6, the reason why the water level position for opening and closing the electric air valve 63 differs when the water level is falling and when the water level is rising is as follows. That is, in order to avoid air-water mixed operation when the water level is rising and falling, "when the water level is falling, if the water level is near the upper edge 531 of the opening 53 of the suction cover 5, the casing 2 is full and a total amount of water is discharged, and when the water level falls below the upper edge 531, air is sucked in from the suction cover 5.

The motorized air valve 63 opens at the "air valve opening level" (in this embodiment, a water level about 10 mm higher than the upper edge 531), which is the water level near the upper edge 531, and air is sucked into the casing 2 from the air pipe 64, causing the water in the casing 2 to drain all at once, and instantly switching from full-flow drainage operation to air-standby operation. ' Also, 'When the water level rises, when the water level reaches 60% or more of the height of the impeller 32, the impeller 32 can discharge the water in the casing 2 by itself. In order to reliably avoid air-water mixed operation at this water level when the water level rises, the motorized air valve 63 closes at the "air valve closing level" (in this embodiment, a water level about 55% of the impeller 32), which is a water level slightly lower than that water level, and air from the air pipe 64 is cut off. When the water level reaches the water level that allows full-flow drainage operation (about 60% of the impeller 32), the operation instantly switches from air-standby operation to full-flow drainage operation. For the above reasons, the water level positions at which the motorized air valve 63 opens and closes differ when the water level is falling and rising.

[Other embodiments]
Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, the electric air valve 63 in the above-mentioned embodiment is a valve driven by an actuator using a motor (electric motor), but it may be an electromagnetic valve using a solenoid electromagnet. In addition, in the above-mentioned submersible mixed flow pump 1 and the submersible axial flow pump 10, the output shaft 31 of the electric motor 3 and the axis of the impeller 32 connected thereto are both arranged horizontally. However, this axis may be inclined from the horizontal. In addition, the air supplied to the air pipe to avoid air-water mixed operation is atmospheric air, but pressurized air may be supplied by a blower or compressor to actively drain the water in the pump casing. Furthermore, the shape of the suction cover 5 of the above-mentioned submersible mixed flow pump 1 and the submersible axial flow pump 10 differs depending on the structure of the submersible pump. Therefore, the suction cover 5 in the present invention is not limited to the cover on the suction side of the pump body, but is a concept that includes the main body part.

Reference Signs List 1...Submersible mixed flow pump 10...Submersible axial flow pump 100...Gate body 101...Bracket 102...Bottom surface of water passage 2...Casing 21...Suction port 22...Discharge port 3...Electric motor 31...Output shaft 311...Shaft center 32...Impeller 33...Guide vane 34...Oil chamber 4...Flap valve 5...Suction cover 60...Air supply circuit 63...Electric air valve

Claims (5)

a casing having a suction port on one side and a discharge port on the other side;
an electric motor fixed within the casing for rotating and driving the device;
an impeller coupled to the output shaft of the electric motor, the output shaft being disposed in a lateral direction in which the axis of the output shaft is horizontal, or the axis of the output shaft being inclined at a predetermined angle from the horizontal, and being rotated;
a suction cover fixed to the casing and having an opening for sucking in a fluid,
an air pipe for drawing air into the submersible pump from a discharge port disposed upstream of the impeller and within the submersible pump;
an air on-off valve for supplying or blocking air to the air pipe ;
A water level meter that detects the water level on the suction port side;
an on-off valve control means for controlling the opening and closing of the air on-off valve based on a water level detection value of the water level gauge ;
The discharge port of the air pipe is disposed opposite the impeller, and a central axis of the discharge port is parallel to the axis of the impeller.
The central axis of the discharge port is disposed at a position lower than the axis of the output shaft.
A submersible pump with an air pipe. 2. The submersible pump with air tube according to claim 1,
The submersible pump with an air pipe is a submersible mixed flow pump in which the flow path of the fluid driven by the impeller is inclined with respect to the axis, or a submersible axial flow pump in which the flow path of the fluid is in the axial direction. 3. The submersible pump with air pipe according to claim 1 ,
The submersible pump with an air pipe, wherein the on-off valve control means controls the water level when opening and closing the air on-off valve differently when the water level is rising and when the water level is falling. 3. The submersible pump with air pipe according to claim 1 ,
An underwater pump with an air pipe, characterized in that the air pipe is connected to the suction cover or the casing. A submersible pump system using the submersible pump with an air pipe according to any one of claims 1 to 4 ,
1. An air pipe-equipped submersible pump system, characterized in that the air pipe-equipped submersible pump is mounted on a sluice gate or a culvert that crosses a river or a waterway.

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