JP2002005069A - Suction bell mouth of pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suction bell mouth of a pump which can easily change performance of the pump. SOLUTION: Straightening vanes 11 having a shape for giving pre-whirling or reverse pre-whirling to the fluid to be sucked into a suction bell mouth 10 are attached to the inside of the suction bell mouth 10. When the straightening vanes 11 give the reverse pre-whirling, a capacity of the pump increases. When the straightening vanes 11 give the pre-whirling, the capacity of the pump decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suction bell mouth of a pump mounted on a suction side of a pump impeller.

[0002]

2. Description of the Related Art In a conventional pumping station, a vertical pump is installed in a suction water tank, and by driving the vertical pump, water flowing into the suction water tank is drained to a predetermined place.

On the other hand, in recent years, it has been required to increase or decrease the pump discharge amount of an existing pump station. As a method of changing the pump performance of the existing pump station, there are a method of replacing the pump with a new pump, and a method of increasing or decreasing the rotation speed of the existing pump.

However, in any of the above methods,
Significant remodeling of the pump equipment is required, and the cost is high. In particular, in the case of the above method, the size of the pump may be increased, and it is necessary to remodel the suction tank to which the pump is to be remodeled significantly.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a pump suction bell mouth which can easily change pump performance.

[0006]

According to the present invention, there is provided a suction bell mouth for a pump mounted on a suction side of a pump impeller, wherein the suction bell mouth is sucked into the suction bell mouth. A rectifying vane having a shape for giving a pre-swirl or reverse pre-swirl to a fluid, or a movable rectifying vane movable to give a pre-swirl or a reverse pre-swirl to a fluid sucked into a suction bell mouth is attached. When the reverse pre-swirl is given, the pump capacity increases, and when the pre-swirl is given, the pump capacity decreases. In other words, the pump performance can be changed (the theoretical head of the pump can be changed) simply by replacing the suction bell mouth.

[0007] It is preferable to provide a center cone at the center of the inside of the suction bell mouth in order to prevent the occurrence of water vortices.

Further, by providing a bearing for a shaft for rotating the pump impeller inside the center cone, the center cone can simultaneously have a function of preventing underwater vortex generation and a bearing function.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic side view showing an example of a vertical shaft pump 30 using the suction bell mouth 10 according to the present invention. As shown in FIG.
A motor (driving means) 37 is installed on a floor 51 of the suction water tank 55 via a motor mount 35, and a suspension pipe 31 is attached to the lower end of the discharge elbow 39 suspended from the floor 51 into the suction water tank 55. The discharge bowl 33 and the suction bell mouth 10 are mounted, and the discharge pipe 38 is mounted on the discharge side of the discharge elbow 39.

FIG. 2 is an enlarged sectional view of a main part showing a peripheral portion of the suction bell mouth 10. As shown in FIG. As shown in the figure, a guide vane 41 is provided in the discharge bowl 33. At the center of the discharge bowl 33, a shaft 45 that is rotationally driven by the electric motor 37 is supported by a radial bearing 47. A pump impeller 49 is fixed to a tip of the shaft 45.

Below the pump impeller 49 on the inner peripheral surface of the suction bell mouth 10, four (or another number) rectifying blades 11 are fixed at equal intervals (90 ° intervals). The rectifying blade 11 is formed into a curved surface shape so that the fluid sucked into the suction bell mouth 10 causes reverse pre-swirling. Here, the reverse pre-swirl means that the fluid sucked into the suction bell mouth 10 is given a swirling flow that swirls in a direction opposite to the rotation direction of the pump impeller 49 before reaching the pump impeller 49. To tell.

[0012] With such a configuration that the reverse pre-swirl is given, the capacity of the pump can be increased. Therefore, for example, when the capacity of an existing vertical shaft pump is required to be increased, the suction bell mouth is simply changed to the suction bell mouth 10 without newly installing a pump or changing the rotation speed of the pump impeller. Can meet the demand.

On the other hand, depending on the pump, a reduction in capacity (reduction in shaft power) may be required. In such a case, the shape of the rectifying blade 11 is pre-rotated by the fluid sucked into the suction bell mouth 10. What is necessary is just to form in the curved surface shape which produces. Here, the pre-swirl means that a swirling flow that swirls in the same direction as the rotation direction of the pump impeller 49 is given to the fluid sucked into the suction bell mouth 10 before reaching the pump impeller 49. Then, for example, when it is required to reduce the capacity of the existing vertical shaft pump, the suction bell mouth may be simply changed to the suction bell mouth 10. The use of the suction bell mouth 10 that gives a pre-swirl can also reduce the pump vibration at the same time.

FIG. 3 is an enlarged sectional view of a main part showing a peripheral portion of a suction bell mouth 10-2 according to another embodiment of the present invention. In the figure, the same or corresponding parts as those in the embodiment shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. The difference between the suction bell mouth 10-2 and the suction bell mouth 10 shown in FIG.
-2, a center cone 13 extending substantially vertically in a substantially columnar shape is provided at the center of the inside.

When the reverse pre-swirl or pre-swirl is generated by the rectifying vanes 11, the swirl of water tends to generate an underwater vortex. Therefore, the center cone 13 is provided to prevent the occurrence of the vortex.

FIG. 4 is an enlarged sectional view of a main part showing a peripheral portion of a suction bell mouth 10-3 according to still another embodiment of the present invention. In the figure, the same or corresponding parts as those of the embodiment shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted. The suction bell mouth 10-3 is different from the suction bell mouth 10-2 shown in FIG. 3 in that the suction bell mouth 10-3 protrudes from the center of the tip of the pump impeller 49 into the center cone 13 of the suction bell mouth 10-3. The point is that a radial bearing 15 that supports the tip of the shaft 45 is provided. As a result, the center cone 13 can have both the function of preventing underwater vortices from occurring and the function of bearing the shaft 45.

FIG. 5 is an enlarged sectional view of a main part showing a peripheral portion of a suction bell mouth 10-4 according to still another embodiment of the present invention. In this figure, the same or corresponding parts as those of the embodiment shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. The difference between the suction bell mouth 10-4 and the suction bell mouth 10 shown in FIG.
1-4.

That is, the rectifying blade 11-4 is provided with the movable piece 17 at a part thereof. In this embodiment, the movable piece 17 is provided above the rectifying blade 11-4, and is configured to be able to swing around the support shaft 17a. Movable piece 17
Is connected to a swing operation mechanism R1 provided outside the suction bell mouth 10-4. Swing operation mechanism R1
Is connected to a motor (not shown) installed on the floor 51 of the suction water tank 55 via a spindle R2 connected by a universal joint U, and the movable piece 17 swings by rotating the spindle R2 by the motor. It is configured to be. However, various other mechanisms can be considered as the swing mechanism of the movable piece 17. The support shaft 17a
Is attached to the end of the movable piece 17 so that the pivot 17
Since the direction of the hydraulic moment acting on a can be made constant, the movable piece 17 can be controlled stably.

If the movable piece 17 is swung, the fluid sucked from the suction bell mouth 10-4 can be given reverse pre-swirl or pre-swirl. That is, not only can one suction bellmouth 10-4 generate reverse pre-swirl and pre-swirl but also the strength of reverse pre-swirl or pre-swirl is required by adjusting the swing angle of the movable piece 17. Can be adjusted freely according to

Needless to say, the suction bell mouth 10-4 may be provided with a center cone 13 and a radial bearing 15 as shown in FIGS.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims and the technical idea described in the specification and the drawings. Is possible. Note that any shape, structure, or material not directly described in the specification and drawings is within the scope of the technical idea of the present invention as long as the effects and effects of the present invention are exhibited. For example, in the above embodiment, the case where the suction bell mouth according to the present invention is used to improve the performance of the existing pump has been described, but it goes without saying that it may be attached to a new pump. When the reverse pre-swirl is given, the pump can be made more compact than a conventional pump having the same capacity. In the embodiment shown in FIG. 4, the radial bearing 15 is provided as a bearing, but a thrust bearing or both may be provided.

[0022]

As described above in detail, according to the present invention, the pump performance can be easily and inexpensively changed simply by attaching the suction bell mouth according to the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an example of a vertical pump 30 using a suction bell mouth 10 according to the present invention.

FIG. 2 is an enlarged sectional view of a main part showing a peripheral portion of a suction bell mouth 10.

FIG. 3 is an enlarged sectional view of a main part showing a peripheral portion of a suction bell mouth 10-2.

FIG. 4 is an enlarged sectional view of a main part showing a peripheral portion of a suction bell mouth 10-3.

FIG. 5 is an enlarged sectional view of a main part showing a peripheral portion of a suction bell mouth 10-4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Suction bellmouth 11 Straightening vane 30 Vertical pump 31 Suspension pipe 33 Discharge bowl 37 Electric motor (drive means) 38 Discharge pipe 39 Discharge elbow 45 Shaft 47 Radial bearing 49 Pump impeller 55 Suction water tank 10-2, 3, 4 Suction bell Mouse 13 Center cone 15 Radial bearing 11-4 Rectifier blade 17 Movable piece

Continued on the front page F term (reference) 3H022 AA01 BA01 BA06 CA13 CA15 CA17 DA00 DA20 3H034 AA01 AA20 BB01 BB07 BB16 CC03 DD02 DD26 DD28 EE01 EE08 EE12 EE15

Claims (3)

[Claims] 1. A suction bell mouth of a pump attached to a suction side of a pump impeller, wherein a rectifying vane having a shape for imparting pre-swirling or reverse pre-swirling to a fluid sucked into the suction bell mouth, inside the suction bell mouth. Alternatively, a suction bell mouth of a pump is provided with a movable rectifying vane which is movable so as to give pre-swirl or reverse pre-swirl to a fluid sucked into the suction bell mouth. 2. The suction bell mouth of the pump according to claim 1, wherein a center cone is provided at a center inside the suction bell mouth. 3. A suction bell mouth for a pump according to claim 2, wherein a bearing for a shaft for rotating and driving the pump impeller is provided inside the center cone.