JPH0361695A - vertical shaft pump - Google Patents

Abstract

PURPOSE:To operate a pump at a full speed to enable waiting of the pump and securely cope with any accidental flood by providing a switch valve controller for opening a switch valve by detecting an aerial operation of the pump while closing the switch valve by detecting the pumping operation of the pump. CONSTITUTION:The lower opening end 7 of the suspension portion 14 of a U-shaped branch pipe 3 connected to a suction casing 2 communicated with an impeller chamber 6 is set at a level corresponding to the lowest water level LWL of a vertical shaft type pump. Meanwhile, a communication port 8 between the branch pipe 3 and the suction casing 2 is set higher than the lowest water level LWL. The bending portion 9 of the branch pipe 3 is formed at a position higher than a suction pumping level due to the maximum negative pressure generated in the impeller chamber 6, and a switch valve 10 is provided in the bending portion for 9 opening and closing the inner passage of the branch pipe 3. Moreover, a switch valve controller 20 is provided for opening the switch valve 10 by detecting the aerial operation of a vertical shaft type pump while closing the switch valve 10 by detecting the pumping operation of the pump.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vertical shaft pump that can be operated at full speed regardless of the water level.

[Conventional technology] Conventional vertical shaft pumps, which have traditionally been installed in pump intake wells at drainage pump stations, generate eddies when the water level is lower than a certain level, causing air to flow out even though the suction port is underwater. Each pump that sucks mixed water has its own minimum water level (minimum operable water level), and if it is operated when the water level has not reached the minimum water level, it will generate vibrations and noise. Therefore, if such a vertical shaft pump is operated at full speed regardless of the water level in the suction well and kept on standby in case of an unexpected water outflow (full speed standby operation), the water level will drop below the above minimum water level. At certain times, severe vibrations and noise may occur, causing pump operation failure or damage to the foundation or building.

Therefore, conventional vertical shaft pumps do not perform full-speed standby operation, but operate only when the water level is higher than the minimum water level, and stop operation when the water level is lower than the minimum water level.

However, in recent years, the water retention function of the strata has been declining due to an increase in paving ratio and a decrease in green areas due to the progress of urbanization, while the amount of water flowing into the above-mentioned water absorption wells has been noticeably increasing. It often happens that a large amount of water suddenly and rapidly flows into a water intake well, like a so-called flash flood. As a result, the water level in water intake wells fluctuates in a short period of time, and with the above operating system using conventional vertical pumps, it is not possible to accurately control the timing of starting and stopping the operation of the vertical pump, resulting in abnormal rises in the water level. There were concerns that this could lead to flooding and pump malfunction due to abnormal decline.

Therefore, in Japanese Patent Application No. 61-280967, the applicant of the present application proposed a vertical shaft pump that can perform stable full-speed standby operation regardless of whether the water level is higher or lower than the minimum water level. As is clear from FIG. 2, this vertical shaft pump has a branch pipe 3 in the suction casing 2 in front (upstream side) of the pump impeller 1 that is much smaller in diameter than the suction port and is open to the atmosphere. At the same time, an intake valve 4 is interposed at the tip of this branch pipe 3, and the opening and closing of this intake valve 4 is controlled by a signal from a water level detector 5.

This vertical shaft pump is operated at full speed on standby. When the water level of the water intake well P is rising from below the minimum water level, the intake valve 4 is opened while the water level detector 5 detects that the water level has not reached the minimum water level. When the water level detector 5 detects that the water level in the water intake well P has reached the minimum water level, the intake valve 4 is controlled to close, and until the water level reaches the minimum water level, the air flow from the branch pipe 3 to the impeller is controlled. Air is drawn into the passenger compartment 6 and water is not pumped,
While the so-called full-speed operation in the air continues without difficulty,
After the water level reaches the minimum water level, the intake of air from the branch pipe 3 to the impeller chamber 6 is stopped, water is pumped, and normal water pumping operation is performed.

On the other hand, when the water level of the water intake well P is falling from above the minimum water level, the intake valve 4 is closed while the water level detector 5 detects that the water level has not reached the minimum water level. Pumping operation continues. When the water level detector 5 detects that the water level has reached the lowest water level, the intake valve 4 is opened and a small amount of air is sucked per unit time into the impeller chamber 6 through the small diameter branch pipe 3, and the suction casing 2 The water filling the tank is shut off, and pumped storage operation can be smoothly switched to air operation.

Therefore, this vertical shaft pump enables full-speed standby operation that can cope with sudden rises and falls in the water level, and prevents the above-mentioned flooding due to abnormal rises in water levels and pump operational failures due to abnormal drops. It becomes possible to do so.

[Problem to be solved by the invention]

However, the water level detector 5 used in this vertical pump is susceptible to adverse effects from water quality, dust, and the like. This is an extremely important issue considering that the vertical shaft pump is required to be able to cope with unexpected water outflows.

The present invention has been made in view of the above circumstances, and it is possible to keep the pump in full speed operation mode in case of a sudden rise or fall in the water level, as well as to prevent flooding or abnormal decline due to the above-mentioned abnormal rise or fall in the water level. It is an object of the present invention to provide a vertical shaft pump that prevents pump operation malfunction due to the above and that can reliably deal with unexpected water outflow without using a water level detector.

[Means for Solving the Problem] The vertical shaft pump according to the invention described in the first claim has the lower open end of the hanging part of the inverted U-shaped branch pipe connected to the suction casing communicating with the impeller chamber. The level is set to correspond to the minimum water level of the vertical shaft pump, while the communication port between the branch pipe and the suction casing is set above the minimum water level, and the suction head is higher than the maximum negative pressure generated in the impeller chamber. The folded part of the branch pipe is formed at a high position,
An on-off valve that opens and closes the internal passage of the branch pipe to the outside is provided in this folded part, and when it detects that the vertical shaft pump is operating in the air, the on-off valve is opened and the vertical shaft pump The present invention is characterized by comprising an on-off valve control means for detecting that the on-off valve is in a pumping operation and closing the on-off valve.

The vertical shaft pump according to the second aspect of the invention employs a non-water supply detection mechanism for detecting that water is not being pumped into the discharge passage in the opening/closing valve control means.

The vertical shaft pump according to the third aspect of the invention employs a rational water detection mechanism for detecting that water is being pumped in the discharge passage communicating with the impeller chamber in the on-off valve control means.

The vertical shaft pump according to the fourth aspect employs a load detection mechanism provided in a prime mover that drives an impeller as the on-off valve control means.

〔Example〕

1A and 1B illustrate a vertical shaft pump according to an embodiment of the invention. This device connects a suction casing 2 in front (upstream side) of a pump impeller 1 with a branch pipe 3 having a much smaller diameter than its suction port, and forms the branch pipe 3 into an inverted U-shape with an open bottom. Set end 7 to the lowest water level LWL above.
, the communication port 8 between the branch pipe 3 and the suction casing 2 is set above the lowest water level LWL, and the height of the folded part 9 of the U-shaped branch pipe 3 is set at the same level as or close to it. The height is set at a position higher than the suction lift due to the maximum negative pressure generated in the impeller chamber 6 when the impeller 1 is operated at full speed. Further, an on-off valve 10 is provided in the folded portion 9 for opening and closing the internal passage of the branch pipe 3 to the outside.
is provided.

Reference numeral 21 denotes a non-water supply detection mechanism that detects that water is not being pumped in the discharge passage of the discharge casing 11 communicating with the impeller chamber 6. The non-water supply detection mechanism 21 employs, for example, a known contact mechanism that detects whether the valve body of the check valve 12 originally interposed in the discharge passage is in the water supply position or in the non-return position. It is possible to do so.

22 is a rational water detection mechanism that detects that water is being pumped into the discharge passage. This rational water detection mechanism 22 may include, for example, an element with different electrical resistance values when wet and dry, or a pair of opposing electrodes disposed in the discharge passage to detect water flow. It is possible to employ a known mechanism such as one that detects the presence or absence of electrical leakage.

23 is a load detection mechanism provided in the prime mover 13 that drives the pump impeller 1. This load detection mechanism 23 detects the prime mover load when water is being pumped by the pump impeller 1 and the prime mover load when water is not being pumped, and is known in itself.

The above-mentioned non-water supply detection mechanism 21, rational water detection mechanism 22, and load detection mechanism 23 each constitute the on-off valve control means 20, and their functions all detect that the vertical shaft pump is operating in air. It has a function of detecting and opening the on-off valve 10, and detecting that the vertical shaft pump is in pumping operation and closing the on-off valve 10. Furthermore, all of the non-water supply detection mechanism 21, rational water detection mechanism 22, and load detection mechanism 23 may be provided, or only two of them may be provided, or only one of them may be provided.

Only one of them may be used to control the on-off valve 10, or the detection results of two or more may be combined to increase reliability.

[For production]

Next, a case where the water level of the water absorption well P rises from below the lowest water level LWL and a case where the water level falls from above the lowest water level LWL will be explained separately.

(1) When the water level rises from below the lowest water level LWL If the water level has not reached the lower open end 7 of the branch pipe 3 as shown by the imaginary line -1 in Figure 1A, the lower part is opened as shown in the same figure. Since the end 7 is open, depending on the negative pressure in the impeller chamber 6, the flow from the lower open end 7 to the branch pipe 3, the communication port 8, as shown by arrow a.
Air is sucked in through the impeller chamber 6, and water is not pumped.
Air driving continues without difficulty. Therefore, the on-off valve control means 20 detects that the vertical shaft pump is operating in air, and the on-off valve 10 is placed in an open state. Therefore, air is also sucked in from the on-off valve 10.

As shown by the solid line in FIG. 1A, when the water level reaches the lowest water level LWL, the lower open end 7 of the branch pipe 3 is sealed with water, so air suction from the lower open end 7 is blocked. However, since the intake of air from the on-off valve 10 continues,
Air is sucked into the discharge passage through the communication port 8 and the impeller chamber 6. Therefore, the on-off valve control means 20 continues to detect that the vertical shaft pump is operating in air, and the on-off valve 10 remains open. Therefore, no water is pumped and submerged operation continues. The water level is the lowest water level LWL and the water level shown by the solid line in FIG. 1B, that is, the water level at which the communication port 8 is submerged.

The same is true when it is between.

As shown by the solid line in Figure 1B, the water level exceeds the water level W2 at which the communication port 8 is submerged, and approaches the tip of the pump impeller 1, or reaches a water level NWL at which part or all of the pump impeller I is submerged. When pumping by the self-blades of the pump impeller 1 is started, the water is pumped into the discharge passage, so the on-off valve control means 20 detects that the vertical shaft pump is in pumping operation, and closes the on-off valve 10. Therefore, suction of air from the branch pipe 3 is completely stopped, and stable pumping operation is performed. After that, even if the water level rises, stable pumping operation will continue. During pumping operation, water is sucked up into the hanging portion 14 of the branch pipe 3 to a height corresponding to the negative pressure in the impeller chamber 6, and the water column becomes balanced with the negative pressure in the impeller room 6, and the branch pipe 3 Water will not be sucked into the impeller chamber 6.

(2) When the water level falls from above the pumping start water level NWL When the water level is above the pumping start water level NWL, the on-off valve 10 remains closed and the pumping operation up to that point continues. When the water level reaches the lowest water level LWL, the water sucked up into the hanging part 14 when the water seal at the lower open end 7 of the branch pipe 3 is released falls, and the lower open end 7 opens. therefore,
Negative pressure in the impeller chamber 6 causes air to flow through the branch pipe 3 and the communication port 8.
The water that is sucked into the impeller chamber 6 through the water, and fills the suction casing 2, etc. is cut off, and water pumping is cut off, and the operation is quickly and easily switched to air operation. Therefore, the on-off valve control means 20 detects that the vertical shaft pump is operating in air, the on-off valve 10 is opened, and air is sucked in from the on-off valve 10 as well.

As is clear from the above explanation, in the above vertical shaft pump,
The transition from submerged operation to pumping operation is the pumping start water level (i.e., the water level NWL at which pump impeller 1 starts pumping with its own blade)
In contrast, the transition from pumped storage operation to submerged operation is performed using the lowest water level LWL as a reference. By appropriately setting the position of the pump impeller 1 and the level of the lower open end 7 of the branch pipe 3, it is possible to provide a relatively large level difference between the pumping start water level and the lowest water level LWL. Therefore, switching behavior between pumping operation and submerged operation will not occur frequently in a short period of time due to small vertical fluctuations in the water level or waving of the water surface, resulting in insufficient air intake to the impeller chamber 6. This prevents the so-called hunting phenomenon in which water is intermittently performed within a short period of time, and smoothly switches between pumping operation and submerged operation.

〔Effect of the invention〕

As described above, according to the vertical shaft pump of the present invention, full-speed standby operation performance can be easily performed, and the hunting phenomenon can be prevented from occurring. Therefore, according to the vertical shaft pump of the present invention, not only can the pump be put on standby in full speed operation in case of a sudden rise or fall in the water level, but also it is possible to prevent water level abnormalities regardless of whether the water level fluctuation is fast or slow. This makes it possible to prevent flooding due to rising water levels and pump operational malfunctions due to abnormal drops. Furthermore, since no water level detector is used, operational reliability is increased, and sudden rises and falls in the water level can be adequately dealt with.

[Brief explanation of drawings]

1A and 1B are explanatory diagrams of the operation of the vertical shaft pump according to the embodiment of the present invention when the water level is rising, and FIG. 2 is an explanatory diagram of the conventional example. 2... Suction casing, 3... Branch pipe, 6...
Impeller chamber, 7... lower open end, 8... communication port between branch pipe and suction casing, 9... folded part of branch pipe,
10... Opening/closing valve, 14... Hanging part of branch pipe, 20...
...Opening/closing valve control means, 21...No water supply detection mechanism, 22
... Rational water detection mechanism, 23... Load detection mechanism, LW
L: Minimum water level of vertical pump.

Claims (1)

[Claims] 1. The lower open end of the hanging part of the inverted U-shaped branch pipe connected to the suction casing communicating with the impeller chamber is set at a level corresponding to the lowest water level of the vertical shaft pump. on the other hand,
The communication port between the branch pipe and the suction casing is set above the minimum water level, and a folded part of the branch pipe is formed at a position higher than the suction lift due to the maximum negative pressure generated in the impeller chamber. An on-off valve is installed in the section to open and close the internal passage of the branch pipe to the outside, and when it detects that the vertical shaft pump is operating in the air, the on-off valve opens and the vertical shaft pump pumps water. A vertical shaft pump comprising an on-off valve control means that detects that the on-off valve is in operation and closes the on-off valve. 2. The vertical shaft pump according to claim 1, wherein the opening/closing valve control means is a non-water supply detection mechanism that detects that water is not being pumped into the discharge passage. 3. The vertical shaft pump according to claim 1, wherein the opening/closing valve control means is a water supply detection mechanism that detects that water is being pumped into the discharge passage communicating with the impeller chamber. 4. The vertical shaft pump according to claim 1, wherein the opening/closing valve control means is a load detection mechanism provided in a prime mover that drives the impeller.