JPH05231376A - Large sized vertical shaft pump - Google Patents

Abstract

PURPOSE:To perform a transfer from air operation to pumping operation with no water hammer by arranging an auxiliary impeller of small size, driven by a submerged motor independently of an impeller, in a suction port casing successively provided in line with a pump casing. CONSTITUTION:In a vertical shaft pump 2 arranged in a pit 1, a suction port casing 4, in which a suction port 5 is positioned by separating a predetermined distance from a pit bottom surface, is successively provided in line with the lower part of a pump casing 3. An impeller 7 fixed to a drive shaft 8 extended to pass through a barrel part 6a of a guide vane 6 in the pump easing 3 and an assist impeller 9 of small size driven by a submerged motor 10 in the vicinity of the suction port 5 are arranged, in this casing 4. A ventilating pipe 11 of interposing an opening/closing valve 12 is opened to an upper position of the assist impeller 9. In a condition that a level of water is positioned between both the impellers 7, 9, the assist impeller 9 is turned to start assist pumping, and then the impeller 7 is turned to start main pumping.

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, and more particularly to a large pump.

[0002]

2. Description of the Related Art A conventional vertical shaft pump is provided with a suction port casing communicating with a pump casing and having an impeller arranged therein, and a discharge pipe, and is operated when a water level reaches a pumping start water level (RWL). Is configured to start. In addition, some pumps that can perform standby operation perform air operation by supplying air into the suction port casing until the water level reaches the pumping start water level (RWL), and the water level becomes the pumping start water level (RWL). When reaching, the supply of air into the suction port casing is stopped, water is sucked into the pump casing through the suction port casing by the suction action of the impeller, and the sucked water is discharged to the discharge pipe to perform the pumping operation.

[0003]

However, in the above-mentioned conventional configuration, when the operation in the air is changed to the pumping operation, the suction action of the impeller abruptly sucks up and sucks up the water in the suction port casing. There is a problem that water impinges on the impeller and gives an impact. Especially, in a large capacity pump, the impact is great and there is a problem that each part of the pump is affected by up thrust and the like. Further, in a large-sized pump, the impeller may have a structure of a movable blade in order to control the pump performance, which causes a problem that the structure becomes complicated.

The present invention is to solve the above problems, and it is possible to shift from the air operation to the pumping operation without giving a water hammer to each part of the impeller and the pump, and to control the pump performance with a simple structure. It is an object of the present invention to provide a large vertical shaft pump capable of performing the above.

[0005]

In order to solve the above-mentioned problems, a large vertical shaft pump of the present invention is provided with a suction port casing forming a suction port in communication with a pump casing, and an impeller and blades in the suction port casing. An auxiliary impeller having a smaller capacity than the vehicle is arranged, the impeller is connected to the drive shaft inserted in the pump casing, and the auxiliary impeller is connected to the submersible motor provided in the suction port casing. .

[0006]

With the above structure, the sub impeller rotates the auxiliary impeller in a state where the water level is located between the auxiliary impeller, and the auxiliary pumping is started by the suction action of the auxiliary impeller. After that, the impeller is driven to rotate by the drive shaft,
The main pumping is started by the suction action of the impeller. Therefore, since the auxiliary pumping is performed before the main pumping by the impeller, the water in the suction port casing suddenly collides with the impeller when the impeller shifts from air operation to pumping operation. This can be alleviated, and the effect of up-thrust etc. on each part of the vertical pump can be reduced.

Further, by adjusting the timing of driving the auxiliary impeller, pumping can be started at a wide range of water levels. Furthermore, the pumping performance of the pump as a whole can be controlled by controlling the rotation speed of the submersible motor and adjusting the pumping by the auxiliary impeller. Further, since the pressurized water pumped by the auxiliary impeller flows into the impeller, the impeller can be protected from cavitation.

Then, when the pumping is completed and the water level is at the lowest water level, the auxiliary impeller is rotated in the reverse direction to stir the remaining water, thereby preventing the generation of a bad odor due to decay. Further, when a plurality of pumps are arranged, the pumping start water level of each pump can be easily changed, and the pumping amount can be adjusted in multiple stages.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a vertical shaft pump 2 arranged in a pit 1 has a suction port casing 4 arranged below a pump casing 3, and a lower end opening of the suction port casing 4 forms a suction port 5 from the bottom surface of the pit 1. They are separated by an appropriate distance.

A guide vane 6 is arranged inside the pump casing 3, an impeller 7 is arranged inside the suction port casing 4, and a drive shaft 8 is arranged so as to penetrate the body portion 6a of the guide vane 6. The impeller 7 is connected and fixed to. Further, an auxiliary impeller 9 is arranged inside the suction port casing 4 near the suction port 5, and the auxiliary impeller 9 is smaller and has a smaller capacity than the impeller 7. The submersible motor 10 arranged inside the casing 4 is connected and fixed. Further, a ventilation pipe 11 is opened in the suction port casing 4 between the impeller 7 and the auxiliary impeller 9,
An on-off valve 12 is provided in the upper part of the ventilation pipe 11.
A drive motor (not shown) is interlocked with the upper end of the drive shaft 8.

The operation of the above structure will be described below.
In the state where the water level in the pit 1 is the minimum water level (LWL) or more and the pumping start water level (RWL) or less, that is, in the state in which it is located between the auxiliary impeller 9 and the impeller 7, the auxiliary impeller 9 is rotationally driven by the submersible motor 10. Auxiliary pumping is started by the suction action of the auxiliary impeller. After that, the impeller 7 is rotationally driven by the drive motor (not shown) via the drive shaft 8, and the main pumping is started by the suction action of the impeller 7.

Further, the impeller 7 may be preliminarily standby-operated. In this case, air is sent from the ventilation pipe 11 to the inside of the suction port casing 4 with the opening / closing valve 12 opened, and the impeller 7 is operated. Drive in the air. Then, as the auxiliary impeller 9 is driven, the on-off valve 12 is closed to shift the impeller 7 from the air operation to the pumping operation.

Therefore, auxiliary pumping is carried out by the auxiliary impeller 9 prior to the main pumping by the impeller 7, so that when the impeller 7 shifts from the air operation to the pumping operation, the water inside the suction port casing 4 is removed. It is possible to mitigate the sudden collision with the impeller 7 and reduce the influence of up-thrust and the like on each part of the vertical shaft pump.

Further, the auxiliary impeller 9 by the submersible motor 10
By adjusting the drive start timing of the above, it is possible to start pumping at a wide arbitrary water level between the auxiliary impeller 9 and the impeller 7.

Further, by controlling the rotation speed of the submersible motor 10 to adjust the pumping by the auxiliary impeller 9, the pumping performance of the entire pump can be improved without using the rotation speed control of the impeller 7 or the movable blade structure. Can be controlled. Further, since the pressurized water pumped by the auxiliary impeller 9 flows into the impeller 7, the impeller 7 can be protected from cavitation.

When the water level is at the lowest level after the pumping is completed, the auxiliary impeller 9 is rotated in the reverse direction by the submersible motor 10 to agitate the remaining water, thereby preventing the generation of a bad odor due to decay. it can.

When a plurality of pumps are arranged,
By adjusting the drive start timing of the submersible motor 10 in each pump, the pumping start water level and the pumping stop water level can be easily changed, and the pumping amount can be adjusted in multiple stages.

[0018]

As described above, according to the present invention, auxiliary pumping is performed by the auxiliary impeller before the main pumping by the impeller, so that the water is rapidly blown at the transition from the air operation to the pumping operation. It is possible to mitigate collision with the vehicle, reduce the effect of up-thrust etc. on each part of the vertical shaft pump, and adjust the start timing of the auxiliary impeller to start pumping at a wide range of water levels. By controlling the rotation speed of the impeller, the pumping performance of the entire pump can be controlled and the impeller can be protected from cavitation.

[Brief description of drawings]

FIG. 1 is a sectional view of a vertical pump according to an embodiment of the present invention.

[Explanation of symbols]

 2 Vertical shaft pump 3 Pump casing 4 Suction port casing 7 Impeller 8 Drive shaft 9 Auxiliary impeller 10 Submersible motor

Claims (1)

[Claims] 1. A drive in which a suction port casing forming a suction port is provided so as to communicate with a pump casing, and an impeller and an auxiliary impeller having a smaller capacity than the impeller are arranged in the suction port casing and inserted into the pump casing. A large vertical axis pump characterized in that an impeller is connected to the shaft, and an auxiliary impeller is connected to a submersible motor provided in a suction port casing.