JP2000027788A - Method for operating vertical shaft pump, and vertical shaft pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the burden to an operator, to lower the equipment cost and installation cost, and to prevent the generation of abnormal vibration and hunting operation. SOLUTION: When water level of a water tank 5 achieves a starting water level SWL, a motor 2 is started so as to cut a fluid joint 4, and a brake 15 is operated so as to prepare for pumping while maintaining the number of revolution of a vane 6 at 0%. When the water level of the water tank achieves a pumping starting water level TWL, the fluid joint 4 is turned to the transmitting condition so as to rotate the vane 6, and speed is raised till the number of revolution of the vane 6 corresponds to 0% of the real pumped variable. When the water level of the water tank rises more and achieves the operable lowest water level LWL, real pumping operation is performed while changing the number of revolution of the vane 6 in response to the water level change ratio of the water tank from the number of revolution corresponding to 0% of the real pumped variable to 100% thereof, and drained variable by a pump main body 1 is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical shaft pump operating method and a vertical shaft pump therefor, and more particularly to a vertical shaft pump suitable for, for example, draining water to a discharge water tank when the water in the water suction tank increases due to rainfall. The present invention relates to a pump operation method and a vertical pump for the same.

[0002]

2. Description of the Related Art FIG. 6 shows an example of a conventional vertical shaft pump.
As shown in the figure, the vertical pump includes a pump main body 1 and a prime mover 2 for driving the pump main body, and further includes a transmission 3 between the pump main body 1 and the prime mover 2 for adjusting a speed and changing a torque transmission direction. The transmission 3 may be provided with a fluid coupling 4, a clutch, and the like in the middle of a torque transmission path. As the prime mover 2, an electric motor or an internal combustion engine such as a diesel engine or a gas turbine is generally used. In the case of using such a vertical pump to drain the increased water content during rainfall from the water absorption tank 5 to a discharge water tank (not shown), the following operation is performed. The starting of the prime mover 2 is performed in a state where the water level of the water suction tank 5 rises to a starting water level SWL which is higher than the lowest operable water level which is higher than the position of the impeller 6 of the pump body 1. At the same time, the power of the prime mover 2 is transmitted to the pump main body 1 to accelerate the impeller 6 to start the pumping operation. Thereafter, the discharge valve 7 is opened and the discharge pipe 17 is connected to a discharge water tank (not shown). Has been released. Also, during this discharge, while the water level in the water absorption tank 5 is between the operable minimum water level LWL and the high water level HWL, the motor 2 or the fluid coupling 4 is controlled to change the rotation speed of the impeller 6, and discharge the pump body 1. Controlling the amount. When the water level in the water absorption tank 5 falls below the minimum operable water level LWL, the motor 2 is stopped and the pumping is terminated.

Another example of a conventional vertical shaft pump is shown in FIG.
This vertical pump is of the type that performs the preliminary standby operation,
In addition to the configuration similar to the example of FIG.
An intake pipe 9 communicating with the lower side is added. In such a vertical shaft pump, the prime mover 2 is started at a starting water level in which the water level of the water absorption tank 5 is lower than the position of the impeller 6, and the impeller 6 is accelerated to a rotation speed of 100% without being submerged. The operation is performed by the full-speed preceding standby system. Therefore, the water absorption tank 5
Until the water level reaches the pumping start water level at which the impeller 6 is positioned, the in-air operation (idle operation) is performed while suctioning air through the intake pipe 9. In this state, when the water level rises due to inflow water due to rainfall and reaches the pumping start water level TWL, the impeller 6 is submerged and pumping is started. At the start of pumping, the water level is still insufficient because the water level is not yet sufficient, and the operation shifts to a stable pumping operation with a pumping amount of 100% as the water level rises. In the case of such an operation method, the discharge amount control of the pump body is not normally performed, and when the water level becomes equal to or lower than the pumping start water level TWL, the air is sucked from the intake pipe 9 and the water level further decreases to become equal to or lower than the starting water level SWL. When this happens, the water below the impeller drops, and the idle operation of the impeller 6 at 100% but no pumping continues. Then, when the water level rises again and becomes equal to or higher than the starting water level, the operation is repeatedly changed to the pumping operation through the air / water stirring operation. The prior art shown in FIG.
No. 150097.

Further, as another conventional example of the preceding standby operation method, there is one disclosed in Japanese Patent Application Laid-Open No. 7-077191. This is because a vertical shaft pump and a prime mover are connected, and a clutch is interposed in the connection path. The prime mover is kept in an operating state at all times, and the clutch is turned on when the water level in the water absorption tank exceeds a water level set to perform suction or discharge, and the clutch is turned off when the water level is below the water level. ing. In this known example, control of the pump speed is not performed.

[0005]

The conventional vertical shaft pump as described above has the following drawbacks, and its improvement has been demanded.

In the vertical shaft pump shown in FIG. 6, the discharge valve 7 is opened after the prime mover 2 is started to start pumping. Therefore, the starting water level SWL must be higher than that of the impeller, and the pumping is started from a state where the water level in the water absorption tank has risen considerably from the normal water level due to rainfall or the like that has already started. However, from the start of the prime mover until the pumping amount in the pump body reaches 100%, 5-10
It generally takes a minute. For this reason, the pump operator
When the water level in the water absorption tank has risen considerably from the normal water level, one has to worry about whether or not the prime mover will operate. In addition, a hunting operation in which sudden start and stop of the prime mover and the pump main body are repeated at the start water level SWL is likely to occur, and the load on the prime mover and the pump main body increases.

On the other hand, in the vertical shaft pump shown in FIG. 7, the prime mover is started at a water level lower than the position of the impeller because of the full speed advance standby system.
L is close to the normal water level. Therefore, the operator can confirm the operation state of the prime mover in the early stage of the start of increasing the water in the water absorption tank due to rainfall or the like, and does not have to be forced into an uneasy state as in the vertical pump shown in FIG. However, up to the pumping start water level TWL after the start of the motor, the impeller is operated at full speed in an empty state where the impeller is not submerged. It is necessary to supply more fresh water, which complicates the overall structure.

In the vertical pump shown in FIG. 7, the starting water level SWL is set at 0.5 D
(D = caliber of the discharge pipe) and bell mouth 13
The lower end of the tank is about 1D lower than the starting water level.
1D is required between the floorboard 14 and the lower end of the bell mouth 13 from the viewpoint of performance. As a result, the water depth from the lowest operable water level LWL that exhibits 100% of the pumping amount to the floorboard 14 needs to be as deep as about 3D, which leads to an increase in the amount of civil engineering excavation.

Further, in the vertical shaft pump shown in FIG. 7, since the impeller is operated at full speed (100% rotation speed) in the state change of air-water-water agitation-pumping, the behavior change of water in the pump main body becomes sharp. Abnormal vibration during operation is likely to occur due to hydraulic thrust, pressure change or shift of the center of gravity. For this reason, it is necessary to increase the strength of the pump body itself as well as its support strength and the strength of the installation floor, resulting in an increase in cost of the entire pump system.

Further, in the vertical shaft pump shown in FIG. 7, since the pump itself pumps or drops water in accordance with a change in the water level of the water suction tank, the operation is simplified, but the pump is installed. When the pump lengths of all the pumps are the same (generally, this is often the case), the pumps start or resume pumping at the same time while operating all the pumps. For this reason, the water level in the water absorption tank fluctuates greatly, and hunting operation, in which pumping and falling water frequently occur, is likely to occur.In addition, when the load is applied to all pumps at the same time, when the motor is a motor, start-up rush current causes abnormalities on the receiving side. It may lead to a voltage drop accident.

Further, in the known example of Japanese Patent Application Laid-Open No. 07-077191, the prime mover can be operated in advance by using a clutch without using an intake pipe. Abrupt changes in inland water behavior are avoided. However, in a clutch that turns on and off the transmission of large power, a rotation phenomenon occurs in which rotation is not completely shut off even when the clutch is turned off due to the viscosity of oil inserted therein for lubrication. Then, even if the pump is not pumping, it will be rotating,
For this reason, there has been a problem that cooling means for the underwater bearing is separately required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional vertical pump, and has been made to reduce the burden on the operator, reduce the equipment cost and the installation cost thereof, and reduce abnormal vibration and hunting operation. It is an object of the present invention to provide a more excellent operation method of the vertical pump and to provide a vertical pump for the prevention.

[0013]

According to the present invention, there is provided a pump body having an impeller at a tip end of a main shaft, a prime mover for driving the pump body, and a power transmission / connection device for connecting the prime mover and the pump body.
In the operation method of the vertical shaft pump having the shut-off means, a brake for stopping the rotation of the vertical shaft pump is provided, and when the water level in the water tank starts rising and reaches a starting water level lower than the impeller, the prime mover is started. A vertical shaft pump, wherein the power transmission / shutoff means is shut off and the brake is actuated to prepare for the start of pumping while maintaining the impeller speed at 0%. The driving method of is provided.

According to the present invention, in the above-described operating method of the vertical pump, when the water level in the water tank further rises and reaches the pumping start water level, the brake is released and the power transmission / shut-off means is set to the transmission state. Provided is an operating method of a vertical shaft pump in which an impeller is rotated and the speed is increased until the rotation speed becomes equivalent to an actual pumping amount of 0%.

According to the present invention, in the operation method of the vertical shaft pump as described above, when the water level of the water tank further rises and reaches the minimum operable water level, the rotation speed of the impeller is further increased to perform the actual pumping operation. During the actual pumping operation, the rate of change of the water level in the water tank is determined, and the rotation speed of the impeller is set to a value between 100% and 100% according to the result. There is provided an operating method of a vertical shaft pump in which the amount of water discharged by a pump main body is adjusted to change.

According to the present invention, in the operating method of the vertical pump as described above, when the water level of the water tank starts to descend and decreases to the starting water level, the power transmission / shutoff means is turned off and the brake is operated. Thus, there is provided an operating method of a vertical shaft pump in which the rotation speed of the impeller is set to 0% while the prime mover is in an operating state and the motor is kept on standby for the next pumping start.

Further, according to the present invention, a vertical shaft pump including a pump main body having an impeller at a tip end portion of a main shaft, a prime mover for driving the main body, and power transmission / shut-off means for connecting the prime mover and the pump main body. When the water level of the water tank starts to rise and reaches the starting water level lower than the impeller, the prime mover is started while the power transmission / shutoff means is shut off to prepare for the start of pumping. When the water further rises and reaches the pumping start water level, the power transmission / shut-off means is set in the transmission state, and the impeller is rotated, and the speed is increased until the rotation speed becomes equivalent to the actual pumping amount of 0%. During this time, when the water level of the water tank further rises and reaches the operable minimum water level, the rotation speed of the impeller is further increased to perform the actual pumping operation, and during the actual pumping operation, Aquarium water The rate of change of the pump body is determined, and the amount of drainage by the pump body is adjusted by changing the number of rotations of the impeller from the number of rotations corresponding to the actual pumping amount of 0% to 100% according to the result. And a method of operating the vertical shaft pump.

Further, according to the present invention, a pump main body having an impeller at a tip end portion of a main shaft, a prime mover for driving the pump main body, a power transmission / shutoff means for connecting the prime mover and the pump main body, and a water level of a water tank are provided. A first control means for starting the prime mover and closing the power transmission / shutoff means so as to prepare for the start of pumping, when the starting water level at a position lower than the impeller is started, and When the water level further rises and reaches the pumping start water level, the power transmission / blocking means is set to the transmission state, and the impeller is rotated, and the speed is increased until the rotation speed becomes equivalent to the actual pumping amount of 0%. And a second control means for performing the actual pumping operation by further increasing the rotation speed of the impeller when the water level of the water tank further rises and reaches the operable minimum water level. In the aquarium In order to determine the rate of change of the position and to control the amount of drainage by the pump body by changing the rotation speed of the impeller from the rotation speed corresponding to the actual pumping amount of 0% to 100% according to the result. And a third control means.

According to the present invention, in the vertical shaft pump as described above, the brake for stopping the rotation of the vertical shaft pump and the brake when the first control means performs control for starting pumping. And a fourth control means for controlling the operation of the pump.

According to the operating method of the vertical shaft pump and the vertical shaft pump according to the present invention as described above, only the prime mover is first started at the starting water level lower than that of the impeller, the power transmission / shutoff means is turned off, and the brakes are turned off. The pump is kept on standby while the impeller of the pump body is maintained at 0% rotation speed by preventing rotation by operation. For this reason, the starting water level can be made close to the normal water level, and while the rise in the water level of the water tank (for example, the water absorption tank) is small, it is possible to confirm the start of the prime mover whose start-up is worried, and it is possible to eliminate anxiety of the operator. . In addition, since the rotation speed of the impeller is set to 0% and the pump body is kept on standby, there is no idle operation of the pump. Therefore, a non-water-supply bearing such as a ceramic bearing can be used, and an external water supply line such as fresh water is not required, so that the system can be simplified. Further, the discharge valve can be opened during standby,
Pumping start time can be shortened.

Further, according to the operation method of the vertical shaft pump and the vertical shaft pump of the present invention, when the water level reaches the pumping start water level, the rotation of the impeller is started, and the pumping pipe of the pump main body is filled with the self-fluid to the underwater bearing. Increase the speed to the level that supplies water.
The rotation speed of the impeller at this time is about 50 to 70% in a normal vertical pump, and this rotation speed has no ability to pump water to the discharge side, and the actual pumping amount, that is, the amount of water pumped to the discharge side is 0%. It will be considerable. In this state, since the state of water changes slowly and the pressure is small, hydraulic thrust and pressure fluctuation can be reduced. Therefore, occurrence of abnormal vibration can be suppressed, and it is not necessary to particularly increase the strength of the pump and its installation, and the cost of equipment and civil engineering can be reduced.

According to the operating method of the vertical pump and the vertical pump in the present invention, the actual pumping operation between the minimum operable water level and the high water level determines the rate of change or the amount of change in the rise and fall of the water level. The impeller rotation speed is continuously changed from the rotation speed corresponding to the actual pumping amount of 0% to 100%, specifically, for example, 50 to 100% by the motor and the fluid coupling used as the power transmission / shutoff means. And the discharge amount of the pump body is adjusted, so that the pumping operation can be performed in accordance with the amount of water flowing into the water tank. For this reason, the water level of the water tank does not drop abnormally, the frequency of turning on / off the pump body is reduced, and hunting of the pump operation can be effectively avoided.For example, the capacity of the water suction tank can be reduced. We can expect that we finish.

According to the operation method of the vertical shaft pump and the vertical shaft pump according to the present invention, when the water level decreases and returns to the pumping start water level again, the rotation speed of the impeller is set to a state where there is no actual pumping (a degree that the pump is filled). Pumping, but no pumping until discharge from the pump), which is the lowest level in the range of 50 to 70%, so that water does not fall from inside the pump body, but the pumping pressure is low. Suction operation is possible without generating cavitation that is harmful to operation. Further, when the water level drops further from this state and the water level drops below the starting water level, the power transmission / shutoff means is shut off and the brake is operated to reduce the rotation speed of the impeller to 0%. As described above, the airlock phenomenon caused by the air / water stirring operation and the rise in the temperature of the residual water in the pump water pipe can be effectively prevented.

According to the operation method of the vertical shaft pump and the vertical shaft pump of the present invention, an intake pipe for sucking air at a position lower than the impeller is not required, so that the space between the starting water level and the lower end of the bell mouth does not need to be so deep. In addition, since the rotation speed of the impeller at the lowest operable water level is as small as 50 to 70%, the depth from the lowest operable water level to the floor is shallower than the conventional pump body, and may be 2D or less. The amount of excavation can be greatly reduced to reduce civil engineering costs. Moreover, even under the condition that the depth of submersion is 2D or less, it is possible to control the rotation speed of the impeller so as not to cause the pump to suction or drift.

According to the operation method of the vertical shaft pump and the vertical shaft pump of the present invention, when it is predicted that continuation of rainfall or the like, the operation of the prime mover does not stop even if the water level becomes lower than the starting water level. Thus, since the restart time can be reduced, the burden on the operator can be reduced, and a stable pump operation can be performed.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. FIG. 1 shows a vertical shaft pump according to the present embodiment in a simplified sectional form. As shown in the figure, the pump body 1 has a structure in which a main shaft 10 supported by a non-water-supplying underwater bearing 11 such as ceramics, and an impeller 6 fixed to the tip of the main shaft 10 are covered by a pumping tube 16 and a bell mouth 13. And driven by the prime mover 2 via the transmission 3. Further, the transmission 3 is provided with a fluid coupling 4 which also functions as a power transmission / shut-off means, and a brake 15 for preventing rotation from occurring after the transmission 3 when only the prime mover 2 is operated.

The relation of the water level in the water absorption tank 5 with respect to the impeller 6 of the pump body 1 is such that the starting water level SWL for starting the prime mover 2 is lower than the impeller 6, and the pumping start water level at which pumping that does not reach actual pumping starts. The TWL is located at a position where the impeller 6 is substantially submerged. Actual pumping with discharge from the pump body 1 is started, and the pumping amount becomes 10
Minimum operable water level to reach 0% (planned minimum water level; LW
L) is located at a position higher than the pumping start water level TWL, and has a height of 2D or less from the bottom plate 14.

FIG. 2 shows an example of a time chart relating to the operation of the vertical pump shown in FIG. When rainwater flows into the water absorption tank 5 due to rainfall, the water level in the water absorption tank 5 starts to rise from a normal water level. Then, at time t1, the starting water level S
When the water level WL is reached, the water level gauge 18 detects this, and based on this, the control device 19 issues a command, so that the prime mover 2 starts and rises to 100% rotation. On the other hand, the pump body 1
, The fluid coupling 4 is shut off and the brake 15 is operated to keep the rotation speed of the impeller 6 at 0% and wait. During this time, the discharge valve 7 of the pump body 1 is opened.

During this time, the water level further rises, and at time t2
When the pumping start water level TWL is reached, the brake 15 is released and the fluid coupling 4 is transmitted to rotate the impeller 6 under the control of the control device 19 based on the detection of the water level gauge 18. In this state, the rotation speed of the impeller 6 is increased to, for example, about 60%. At this speed, the pumping line 1
Although there is pumping up to the inside of No. 6, there is no ability to pump up to the discharge side, and the actual pumping amount is equivalent to 0%.

Then, when the water level further rises and reaches the minimum operable water level at time t3, the control device 19 calculates the rate of change of the water level from the rise in the water level of the water absorption tank 5 detected by the water level gauge 18, According to the water level change rate obtained in this way, the rotation speed of the impeller 6 is increased from, for example, 60% or more to a maximum of 10%.
Speed up in the range of 0%. By this operation, the pump body 1
Keeps pumping and discharging from the water absorption tank 5 to the discharge water tank 8.

If the water level in the water absorption tank 5 falls below the high water level HWL while continuing this operation, the rate of change of the water level becomes negative. Then, the number of revolutions of the impeller 6 is reduced according to the water level change rate in the descent, and at time t4 when the water level returns to the lowest operable water level LWL, the water level drops to, for example, about 60%. Thereafter, when the water level further decreases and drops to the starting water level SWL at time t5, the fluid coupling 4 is shut off and the brake 15 is operated to set the rotation speed of the impeller 6 to 0% and wait. During this time, even if the water level further drops and becomes equal to or lower than the starting water level SWL, if there is a possibility of continued rainfall, the motor 2 is maintained at 100% rotation, and at time t6 when it rises in the next rainfall. Prepare for operation.

Next, with reference to FIGS. 3 to 5, the concept of control of the impeller rotation speed between the starting water level SWL and the lowest operable water level LWL in the present invention will be described. FIG.
Means that the lowest water level L of the discharge water tank 8 is the pipe bottom position 1 of the discharge pipe 17
FIG. 4 shows a case where the lowest water level L of the discharge water tank 8 is higher than the pipe bottom position 17L of the discharge pipe 17. In any of these cases, when the water level in the water absorption tank 5 rises and reaches the starting water level SWL, the motor is started up to 100% rotation, while the rotation speed of the impeller 6 is increased to the pumping start water level TWL. Maintain at 0%. Here, the difference between the pumping start water level TWL and the bottom of the discharge pipe is Ha1 (in the case of FIG. 3), and the difference between the pumping start water level TWL and the minimum water level L of the discharge water tank 8 is Ha2 (in the case of FIG. 4). . FIG. 5 shows the characteristic of the flow rate versus the head of the pump with the number of rotations as a parameter.
In other words, the pump speed at which the actual pumping is 0% is
In the case of FIG. 3, it is the rotation speed of the curve passing through the head Ha1 and the flow rate 0, which is about 55%. In the case of FIG.
a2, the number of revolutions of the curve passing through the flow rate 0, which is about 68%. That is, if the impeller 6 is rotated at a rotation speed of about 55% in the case of FIG. 3, and if the impeller 6 is rotated at a rotation speed of about 68% in the case of FIG. 4, the discharge amount becomes 0%. Although there is no actual pumping, the interior of the pumping pipe 16 can be filled with the self-liquid water, and the self-liquid water can be supplied to the non-water-supplying bearing 11 to obtain lubrication and cooling effects. From this, the actual pumping amount is 0%
Is generally in the range of 50 to 70%, which is the reason why the pump rotation speed after the brake is released is about 60%.

The above embodiment is an example in which the vertical shaft pump is applied when draining water from the water suction tank into which rainwater flows into the discharge water tank. However, the present invention is applied to other cases,
It can be easily understood by those skilled in the art that the effects of the present invention can be exhibited.

[0034]

As described above, according to the present invention,
With respect to the vertical pump, the burden on the operator can be reduced, the equipment cost and the installation cost can be reduced, and abnormal vibration and hunting operation can be effectively prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a state in which a vertical shaft pump according to an embodiment of the present invention is installed in a water absorption tank.

FIG. 2 is a time chart relating to the operation of the vertical pump of FIG. 1;

FIG. 3 is an explanatory diagram when the lowest water level of the discharge water tank is lower than the bottom of the discharge pipe.

FIG. 4 is an explanatory diagram when the lowest water level of the discharge water tank is higher than the bottom of the discharge pipe.

FIG. 5 is an explanatory diagram of rotation control of an impeller in a low water level state of a water absorption tank in the vertical shaft pump according to the present invention.

FIG. 6 is a sectional view schematically showing a state in which a conventional vertical pump is installed in a water absorption tank.

FIG. 7 is a schematic sectional view showing a state in which another conventional vertical shaft pump is installed in a water absorption tank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump main body 2 Motor 3 Transmission 4 Fluid coupling (power transmission / shutoff means) 5 Water absorption tank (water tank) 6 Impeller 7 Discharge valve 8 Discharge water tank 10 Main shaft 11 Underwater bearing 13 Bell mouth 14 Bottom board 15 Brake 16 Pump pipe 17 Discharge Pipe 18 Water level gauge 19 Control device

Claims (7)

[Claims] 1. A method of operating a vertical shaft pump comprising a pump main body having an impeller at a tip end of a main shaft, a prime mover for driving the main body, and power transmission / shut-off means for connecting the prime mover and the pump main body. In the above, a brake for stopping the rotation of the vertical shaft pump is provided, and when the water level in the water tank starts to rise and reaches a starting water level lower than the impeller, the motor is started while the power transmission / shutoff means is shut off. And operating the brake to prepare for the start of pumping while maintaining the rotation speed of the impeller at 0%. 2. When the water level in the water tank further rises and reaches the pumping start water level, the brake is released and the power transmission / shutoff means is in the transmission state to rotate the impeller, and the number of rotations is equal to the actual pumping amount. The operating method of the vertical shaft pump according to claim 1, wherein the speed is increased until the speed becomes equal to 0%. 3. When the water level in the water tank further rises and reaches the minimum operable water level, the actual pumping operation is performed by further increasing the rotation speed of the impeller. The rate of change of the water level of the impeller is obtained.
3. The operating method of the vertical shaft pump according to claim 2, wherein the amount of water discharged by the pump body is adjusted by changing the amount between 00%. 4. When the water level of the water tank starts to descend and drops to the starting water level, the power transmission / shutoff means is turned off and the brake is operated, and thus the rotation speed of the impeller is reduced while the motor is operating. 4. The operating method of the vertical shaft pump according to claim 3, wherein the pump is set at 0% to be on standby for the next pumping start. 5. A method of operating a vertical shaft pump comprising a pump main body having an impeller at a tip end portion of a main shaft, a prime mover for driving the main body, and power transmission / shut-off means for connecting the prime mover and the pump main body. When the water level in the water tank starts to rise and reaches the starting water level lower than the impeller,
When the water level in the water tank rises further and reaches the pumping start water level, the power transmission and
The impeller is rotated with the shut-off means in the transmitting state, and the speed is increased until the number of revolutions becomes equivalent to the actual pumping amount of 0%, and this state is maintained. During this time, the water level in the water tank further rises. When the minimum operable water level is reached, the actual pumping operation shall be performed by further increasing the rotation speed of the impeller, and during this actual pumping operation, the rate of change in the water level of the water tank is determined, and the rate of change is determined according to the result. A method of operating a vertical shaft pump, wherein the number of rotations of an impeller is changed from the number of rotations corresponding to the actual pumping amount of 0% to 100% to adjust the amount of water discharged by the pump body. 6. A pump main body having an impeller at a tip end of a main shaft, a prime mover for driving the pump main body, a power transmission / shutoff means for connecting the prime mover and the pump main body, and a water tank whose water level rises. When the starting water level reaches a position lower than the impeller for the first time, the prime mover is started while power transmission and
First control means for closing the shut-off means so as to prepare for the start of pumping; and when the water level of the water tank further rises and reaches the pumping start water level,
Second control means for rotating the impeller with the power transmission / shut-off means in a transmission state and increasing the speed until the rotation speed becomes equivalent to the actual pumping amount of 0%; When the water level rises and reaches the minimum operable water level, the actual pumping operation shall be performed by further increasing the rotation speed of the impeller, and during this actual pumping operation, the rate of change in the water level of the water tank is determined. And a third control means for controlling the amount of drainage by the pump body by changing the rotation speed of the impeller from the rotation speed corresponding to the actual pumping amount of 0% to 100% in accordance with the following. A vertical shaft pump comprising: 7. A brake for stopping the rotation of the vertical shaft pump, and a fourth control for controlling the brake to operate when the first control means is performing control for preparing to start pumping. 7. The vertical shaft pump according to claim 6, comprising means.