JP3133116B2 - Vertical pump - Google Patents

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 vertical pump installed in a water absorption tank to enable a water pumping operation even when the water level in the water absorption tank is low, for example, for draining out water during rainfall. The present invention relates to a vertical pump that is suitable as a pump for performing a preliminary standby operation and that can be used for a pump management operation in normal times.

[0002]

2. Description of the Related Art In recent years, due to an increase in a rainwater impervious area due to an increase in the pavement rate of roads, a sudden inflow of rainwater into a rainwater drainage pumping station called an urban flood has become a problem.
For this reason, in order to prepare for a sudden rise in the water level of the water absorption tank (pump pit) during rainfall, a precedence standby operation pump that operates the pump from a state where the water level of the water absorption tank is lower than the specified water level has been put to practical use. For example, as described in Japanese Patent Application Laid-Open No. 1-315691, an intake hole is provided in a suction side casing below an impeller, and an intake pipe communicating between the vicinity of the inlet of the impeller and the atmosphere outside the pump is connected. It has been known.

[0003] In the above technique, when the water level in the water absorption tank is lowered, the flow rate is controlled by sucking air from an intake hole to lower the pumping capacity of the pump, and when a certain water level is reached, the pumping is stopped and the operation shifts to idling. Although the preparatory standby operation is performed, when the preparatory standby operation is performed only with the above configuration, during gas-liquid two-phase flow operation in which water is pumped while suctioning air, pressure imbalance occurs in the flow path in the pump impeller. As a result, the vibration of the pump increases. Under certain conditions, it may not be possible to continue operating the pump. Therefore, the prior art alone has a problem that the preceding standby operation pump cannot have the same reliability as the normal operation pump.

[0004]

In the above-mentioned prior art, there is no means for suppressing the pressure imbalance in the impeller flow path during the gas-liquid two-phase flow operation. As a result, the pump impeller is subjected to a fluid exciting force, There was a problem that vibration increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the prior art, and suppresses imbalance due to air inflow in a pump performing a gas-liquid two-phase flow operation and reduces vibration caused by a fluid excitation force. It is an object of the present invention to provide a vertical shaft pump that improves reliability of preceding standby operation.

[0006]

In order to achieve the above object, a first aspect of the invention relates to a vertical shaft pump according to the present invention, wherein a pump shaft on which an impeller hub is fitted is provided with a shaft center of a pumping pipe of a pump casing. In the vertical shaft pump having a suction bell mouth on the suction side casing of the impeller, a suction side casing below the impeller, and an intake pipe connected to the suction hole, Of the pressure generated in the flow path,
A pressure adjusting hole for balancing pressures at symmetrical positions with respect to the pump axis is provided between impeller vanes on the outer peripheral surface of the impeller hub.

To achieve the above object, a second aspect of the invention relates to a vertical pump according to the present invention, wherein a pump shaft to which an impeller hub is fitted is arranged in the axial direction of a pumping pipe of a pump casing. A suction bell mouth is provided in the suction side casing of the car, and an intake hole is provided in the suction side casing below the impeller,
In a vertical shaft pump in which an intake pipe is connected to the intake holes, pressure adjustment holes are opened at substantially symmetrical positions with respect to the pump axis of the impeller hub, and the respective holes are connected by a pressure adjustment pipe. . Another feature is that the impeller hub
The pressure adjusting hole that communicates the flow path in the impeller with the hollow portion at the center of the impeller hub is provided by an integral multiple of the number of blades of the impeller. Still another feature is that a pressure adjusting hole is provided at a position where the pressure of the impeller hub becomes a negative pressure, or a pressure adjusting hole is provided at a position where the pressure of the impeller hub becomes a positive pressure. It is in.

In order to achieve the above object, a third aspect of the present invention relates to a vertical shaft pump according to the present invention, wherein an impeller is disposed in a casing liner of a pump casing and an impeller hub is fitted thereto. Is arranged in the axial direction of the pumping pipe of the pump casing, has a suction bell mouth in the suction side casing of the impeller, has an intake hole in the suction side casing below the impeller, and connects the intake pipe to this intake hole. In the vertical shaft pump, a pressure adjusting hole is provided in the casing liner by an integral multiple of the number of blades of the impeller, and the holes at symmetrical positions are connected by a pressure adjusting pipe.

[0009]

[0010]

[Action] FIGS 9 and operable by the technical means 10
And the principle will be clarified. FIG.
FIG. 10 is an operation explanatory view showing the imbalance of the pressure on the blades of the impeller, and FIG. 10 is a configuration diagram illustrating the principle of the present invention. FIG. 9 shows a cross-sectional shape of the blade and a pressure distribution state or a pressure gradient in a corresponding portion of each portion of the blade. In general, it is known that the impeller of the vertical pump during the drainage operation has a region where the pressure becomes negative on the blade negative pressure surface as shown in FIG. 9.

When the vertical shaft pump sucks air and performs gas-liquid two-phase flow operation, bubbles stay in the area where negative pressure is indicated by a broken line in FIG. 9 (near the presence of a negative pressure gradient), and the impeller flow path To reduce pump performance. Since the retention of the bubbles is unbalanced for each blade of the impeller of the vertical shaft pump, the pressure in the impeller becomes unbalanced, generating a fluid exciting force and causing the pump to vibrate. Therefore, it is necessary to balance the pressure in the impeller and reduce the fluid excitation force.

In the first invention, as shown in FIG. 10, a pressure adjusting hole 13 is provided at a position where the hub of the impeller 1 becomes a negative pressure, and the symmetrical positions are connected to balance the mutual pressure. The pumping force of the fluid was suppressed and the gas-liquid two-phase flow operation of the pump with less vibration was enabled. According to the second aspect of the present invention, the pressure adjustment holes are opened substantially symmetrically with respect to the pump axis of the impeller hubs, and the respective holes are connected by a pressure adjustment pipe to balance the mutual pressures of the impeller flow paths. It was made possible. Further, by providing the pressure adjusting hole 14 at a position where the positive pressure of the impeller boss becomes positive, it is possible to balance the pressure at a high pressure position.

[0013] In a third invention, provided with a pressure adjusting hole in the casing liner When connected to the pressure adjusting hole of the symmetric position by the pressure regulating pipe, made it possible to balance the pressure of the mutual impeller passages.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to description of each embodiment of the present invention , first, a general configuration and operation of a vertical shaft pump to which the present invention is applied will be described with reference to FIG. FIG. 8 is a schematic configuration diagram of a general vertical shaft pump. In FIG. 8, a casing liner 3 accommodating a pump casing 2 and an impeller 1 is shown.
The suction bell mouth 4 of the pump casing is connected to the lower side, and the pumping pipe 5 and the discharge elbow 6 which are part of the pump casing are connected to the upper side to form a vertical shaft pump. A discharge pipe 7 is provided on the discharge side of the discharge elbow 6.
And a discharge valve 8.

Although not shown in FIG. 8, the pump shaft 12 fitted with the impeller hub is connected to the pumping pipe 5 of the pump casing.
In the axial direction (vertical direction). An intake hole 9 is provided near the bottom of the impeller 1 (the upper part of the suction bell mouth 4 in FIG. 8), and an intake pipe 10 is connected to the intake hole 9.
An intake air amount adjusting valve 1 is provided at the rising part of the intake pipe 10.
1, the suction port 10a of the intake pipe 10 is located at a position higher than the maximum water level HWL in the water absorption tank, and these constitute a flow control device. The intake hole 9 is provided at a position where the air is not sucked from the intake hole 9 at the conventional minimum water level, that is, at the minimum water level WL1 at which the air is sucked from the suction bell mouth 4 below this water level.

Now, the vertical pump is operated at a water level WL4 higher than WL1, and when the water level decreases and the water level in the water suction tank reaches WL1, air is sucked into the pump from the intake hole 9. As the water level decreases, the amount of air to be taken in also increases, and the pump cannot be pumped at the water level WL3, and the idle operation is performed. Thereafter, the water level rises again, and when the water level reaches WL2, the pump operates in a gas-liquid two-phase flow while sucking air. When the inflow amount into the water absorption tank is larger than the pumping amount, the water level rises. The ascent is continued, and when WL1 is reached, the suction of air is stopped, and a transition is made to normal pumping operation.

Embodiments of the present invention applied to the vertical shaft pump performing such a preliminary standby operation will be described with reference to FIGS. 1 to 7 together with FIG. First, embodiments of the first and second inventions will be described. Embodiment 1 FIG. 1 is a cross-sectional view of a main part in the vicinity of an impeller of a vertical shaft pump according to an embodiment of the present invention, and FIG. 2 is a view taken along line XX of FIG.
In the figure, those having the same reference numerals as those in FIG. 8 are the same as those of a general vertical shaft pump, and therefore, the description thereof is omitted. In the embodiment shown in FIGS. 1 and 2, pressure adjusting holes 13 are provided as pressure adjusting means in the flow path of the impeller 1 at symmetric positions with respect to the axis of the pump shaft 12 of the impeller hub 16. The pressure adjustment holes are connected by pressure adjustment piping 17 (22).

The impeller 1 of the vertical pump according to the present embodiment.
Has a plurality of (four in the example shown in FIG. 4) impeller vanes 18, 19, 20, 21 fixed to the impeller hub 16. A pressure adjusting hole 13 is provided in an impeller hub 16 having an impeller vane 18, and a pressure adjusting hole 13 is provided in an impeller hub 16 having an impeller vane 19 at a symmetrical position with respect to the pump axis. The connection is made by an adjustment pipe 17. Similarly, a pressure adjusting hole 13 is provided in the impeller hub 16 having the impeller vane 20, and the pressure adjusting hole 13 is provided in the impeller hub 16 having the impeller vane 21 at a position symmetrical with respect to the pump axis.
And the two pressure adjustment holes are connected by a pressure adjustment pipe 22.

When the vertical shaft pump shown in FIG. 8 starts the gas-liquid two-phase flow operation, air bubbles stay near the impeller 1 where a negative pressure gradient exists. At this time, the impeller vanes 18 and 19 in FIG.
Has a pressure imbalance, a difference is generated in the amount of retained bubbles, resulting in imbalance, and a fluid excitation force is generated. Therefore, the pressure difference is released from the high pressure portion to the low pressure portion by using the pressure difference by the pressure adjusting hole 13 and the pressure adjusting pipe 17, and the pressure in the impeller at the symmetric position is balanced. Similarly, with respect to the impeller vanes 20 and 21 at the other symmetric positions, the impeller hub 16 also has a pressure adjusting hole 13 and a pressure adjusting pipe 2.
2 is provided to balance the pressure of the entire impeller 1 and reduce the fluid exciting force.

Embodiment 2 FIG. 3 is a sectional view of a main part of an impeller of a vertical shaft pump according to another embodiment of the present invention. In the embodiment shown in FIG. 3, as the pressure adjusting means in the flow path of the impeller, a pressure adjusting hole 24 is provided in the impeller hub 16 so as to penetrate a hollow portion 23 at the center of the hub. In addition, in the example shown in FIG.
Although an example in which one is provided for each impeller vane is shown, an integral multiple of the number of blades, for example, two for each impeller vane may be provided. According to the embodiment of FIG. 3, when a pressure imbalance occurs, the pressure can be balanced by the hollow portion at the center of the hub having a uniform pressure distribution, and the fluid excitation force can be reduced.

Embodiment 3 FIG. 4 is a sectional view of a main part of a vertical shaft pump according to still another embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same parts, and a description thereof will be omitted. In the embodiment shown in FIG. 4, the pressure adjusting hole 14 is provided at a position where a positive pressure gradient of the impeller hub 16 occurs. Even if you do this,
The same effects as those of the embodiment shown in FIGS. 1 to 3 can be obtained.

Next, an embodiment of the third invention will be described. Embodiment 4 FIG. 5 is a sectional view of a main part of a vertical shaft pump according to still another embodiment of the present invention. In the drawing, those having the same reference numerals as those in FIG. 1 or FIG. 8 are the same as those in the previous embodiment, and the description thereof will be omitted. In the embodiment shown in FIG. 5, the casing liner 3A in which the impeller 1A is arranged is provided with a pressure adjusting hole 25 for communicating the impeller flow path with the atmosphere, and the pressure is adjusted at a position symmetrical with respect to the pump axis of the casing liner 3A. An adjusting hole 25 is provided, and the two holes are connected by a pressure adjusting pipe 26.

In the example shown in FIG. 5, the pressure adjusting holes 25 provided in the casing liner 3A are provided one for each flow path of each impeller vane. Two impeller vanes may be provided for each channel. According to the present embodiment, when a pressure difference occurs in the impeller channel, the pressure adjusting hole 25 and the pressure adjusting pipe 26 provided at the position of the impeller channel of the casing liner 3A.
Thus, the pressure can be balanced, and the vibration due to the fluid excitation force can be reduced.

Next, an embodiment of the fourth invention will be described. Embodiment 5 FIG. 6 is a sectional view of a main part of a vertical shaft pump according to still another embodiment of the present invention, and FIG. 7 is a sectional view taken along line YY of FIG.
In the figure, components having the same reference numerals as those in FIG. 1 are the same as those in the previous embodiment, and the description thereof will be omitted. In the embodiment shown in FIGS. 6 and 7, the impeller vane 27 of the impeller 1B is provided with a pressure adjusting hole 28 penetrating the pressure surface and the suction surface.

According to this embodiment, by providing the pressure adjusting hole 28 at a position where the negative pressure gradient of the impeller vane 27 exists, the imbalance between the blade pressure surface and the negative pressure surface is eliminated, and the fluid vibration The force can be reduced.

[0026]

As described above in detail, according to the present invention, the imbalance due to the inflow of air in the pump performing the gas-liquid two-phase flow operation is suppressed, and the vibration caused by the fluid excitation force is reduced. It is possible to provide a vertical pump that improves the reliability of the preliminary standby operation.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part near an impeller of a vertical shaft pump according to an embodiment of the present invention.

FIG. 2 is a view as viewed in the direction of arrows XX in FIG. 1;

FIG. 3 is a sectional view of a main part of an impeller of a vertical shaft pump according to another embodiment of the present invention.

FIG. 4 is a sectional view of a main part of a vertical shaft pump according to still another embodiment of the present invention.

FIG. 5 is a sectional view of a main part of a vertical shaft pump according to still another embodiment of the present invention.

FIG. 6 is a sectional view of a main part of a vertical shaft pump according to still another embodiment of the present invention.

FIG. 7 is a sectional view taken along the line YY of FIG. 6;

FIG. 8 is a schematic configuration diagram of a general vertical shaft pump.

FIG. 9 is an operation explanatory view showing an imbalance in pressure of blades of an impeller.

FIG. 10 is a configuration diagram illustrating the principle of the present invention.

[Explanation of symbols]

 1, 1A, 1B Impeller 3, 3A Casing liner 4 Suction bell mouth 5 Pumping pipe 9 Intake hole 10 Intake pipe 12 Pump shaft 13, 14, 24, 25 Pressure adjustment hole 16 Impeller hub 17, 22, 26, Pressure adjustment Piping 18, 19, 20, 21, 28 Impeller vane 23 Cavity

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigeyoshi Ono 603, Kandamachi, Tsuchiura-shi, Ibaraki Pref. Hitachi Tsuchiura Engineering Co., Ltd. (56) References JP-A-1-315691 (JP, A) JP-A-3- 164595 (JP, A) JP-A-2-230996 (JP, A) JP-A-58-177584 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04D 15/00 F04D 13 / 00

Claims (6)

(57) [Claims] A pump shaft fitted with an impeller hub is disposed in the axial direction of a pumping pipe of a pump casing, has a suction bell mouth on a suction side casing of the impeller, and is provided on a suction side casing below the impeller. In a vertical shaft pump having an intake hole and an intake pipe connected to the intake hole, a pressure adjusting hole for balancing pressures generated at a flow path in the impeller at symmetric positions with respect to the pump axis. Is provided at a position between the impeller vanes on the outer peripheral surface of the impeller hub. 2. A pump shaft fitted with an impeller hub is disposed in the axial direction of a pumping pipe of a pump casing, has a suction bell mouth on a suction side casing of the impeller, and is provided on a suction side casing below the impeller. In a vertical shaft pump having an intake hole and an intake pipe connected to the intake hole, pressure adjustment holes are opened at substantially symmetric positions with respect to the pump axis of the impeller hub, and a pressure adjustment pipe is provided between the holes. A vertical pump connected to the pump. 3. The impeller hub is provided with a pressure adjusting hole for communicating the flow path in the impeller and a hollow portion in the center of the impeller hub with an integral multiple of the number of blades of the impeller. 1
Vertical shaft pump as described. 4. At a position where the pressure of the impeller hub becomes a negative pressure,
The vertical shaft pump according to claim 2, wherein a pressure adjusting hole is provided. 5. A position where the pressure of the impeller hub becomes a positive pressure,
The vertical shaft pump according to claim 2, wherein a pressure adjusting hole is provided. 6. An impeller is disposed in a casing liner of a pump casing, a pump shaft fitted with an impeller hub is disposed in an axial direction of a pumping pipe of the pump casing, and a suction bell is mounted on a suction side casing of the impeller. In a vertical shaft pump having a mouse and having an intake hole in a suction side casing below an impeller, and connecting an intake pipe to the intake hole, the casing liner may be provided with a pressure adjustment hole having an integer of the number of blades of the impeller. A vertical shaft pump characterized in that the holes are provided twice and the holes located at symmetrical positions are connected by a pressure adjusting pipe.