JPH07332293A - Suction strainer for pump - Google Patents

Abstract

PURPOSE:To prevent the lowering of numerical aperture of filter holes caused by plugging so as to dissolve the reduction of pump discharge by providing a communicating pipe for communicating a balance hole with a cutter storage part and jetting the led-out discharge water downward from the upper part of the cutter storage part so as to be loaded by the pressure receiving face. CONSTITUTION:At the operating time of a multistage vertical shaft pump, discharge water discharged into a discharge bowl from an impeller is partially led out of a balance hole, flows into the upper part of an annular cutter storage part 9 through a communicating pipe 14 and is jetted downward. The downward jetted discharge water W is loaded by the inclined pressure receiving face 13A of a cutter plate 13 so as to rotate an annular cutter 10 in the direction of an arrow mark X inside the cutter storage part 9. The cutting edge 13a of each cutter plate 13 is placed close to the inner peripheral surface of the peripheral wall 3 of a suction bell 1. Accordingly, even if narrow, long foreign matter enters filter notes 4, 4,... to close them, the foreign matter can be cut by the cutting edge of each cutter plate 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suction strainer for a vertical shaft pump mainly installed in a river or the like.

[0002]

2. Description of the Related Art Conventionally, a multistage vertical pump P shown in FIG. 5 has been known as a vertical pump mainly installed in a river or the like. In this type of multi-stage vertical pump P, a suction strainer 2 is attached to the lower end of the suction bell 1 in order to prevent foreign matter from entering the pump. This suction strainer 2
Has a bottomed cylindrical structure in which a plurality of filtration holes 4, 4, ... Are formed in the peripheral wall 3.

In the conventional suction strainer 2, however, it is difficult to avoid the intrusion of slender foreign matter such as river algae, even though it is possible to avoid the intrusion of large solids, and the plurality of filtration holes 4 are used. , 4 ... Intrude slender foreign matter into the nozzles to cause clogging, reduce the opening ratio of the filtration holes 4, 4 ..., and reduce the pumping rate, which adversely affects the pump performance.

Such a drawback is that the suction strainer 2 is equipped with a cutter that rotates along the inner circumference of the peripheral wall 3,
It is thought that this can be solved by cutting the slender foreign matter blocking the filtering holes 4, 4 ... With a cutter. However, since it is necessary to separately install a drive mechanism for rotating the cutter, the structure becomes complicated and the cost increases.

On the other hand, in this type of multi-stage vertical shaft pump P, in order to reduce the thrust applied to the main shaft 5, a balance hole 7 is provided in the discharge bowl 6 and a part of the discharge water discharged from the impeller 8 is supplied. It is configured to be discharged from the balance hole 7 to the outside of the pump P. The present inventors have paid attention to this point, and have completed the present invention by constructing such that a part of discharge water that has been simply discharged in the past is effectively used as rotational energy of a cutter.

[0006]

The problem to be solved by the present invention is that in the conventional suction strainer, slender foreign matter such as river algae causes clogging, which lowers the opening ratio of the filtration holes and increases the amount of pumped water. It has a negative impact on pump performance, and a cutter that rotates along the inner circumference of the peripheral wall of the suction strainer is installed so that the elongated foreign matter blocking the filtration hole is cut by the cutter. Since it is necessary to separately install a drive mechanism for rotating the cutter, the structure is complicated and the cost is increased.

[0007]

According to the present invention, there is provided a suction strainer having a bottomed cylindrical structure, which is attached to a lower end of a suction bell of a pump and has a plurality of filtration holes formed in a peripheral wall thereof. A cutter accommodating portion is formed, and an annular cutter having a cutter plate having a pressure receiving surface inclined with respect to the axis is rotatably accommodated in the cutter accommodating portion, and discharge water discharged from the impeller is A balance hole for leading out a part is provided, and the balance hole and the cutter accommodating portion are communicated with each other, and the discharged discharge water is jetted downward from the upper portion of the cutter accommodating portion to load the pressure receiving surface. The feature is that the pipe is provided, and even if slender foreign matter enters and blocks the filter hole of the suction strainer of the pump, it can be reliably cut with a simple structure, Preventing a reduction aperture ratio of the filter holes by Mari was achieve the purpose of avoiding the adverse effect on pump performance by eliminating the reduction of pumping volume.

[0008]

According to the present invention, a part of the discharge water discharged from the impeller to the discharge bowl is led out from the balance hole, passes through the communication pipe, and enters the upper portion of the cutter accommodating portion to be jetted downward. The downwardly ejected water is loaded on the inclined pressure receiving surface of the cutter plate, the annular cutter is rotated in the annular cutter accommodating portion, and the elongated foreign matter that has entered the filter hole and is blocked is cut by the cutter plate. be able to.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a multistage vertical shaft pump to which the present invention is applied, FIG. 2 is an enlarged sectional view of an essential part, and FIG. 3 is a bottom view of an annular cutter. It should be noted that the same or corresponding portions as those in the conventional example will be described by attaching the same reference numerals. 1 to 3, at the lower end of the suction bell 1, a suction strainer 2 having a bottomed cylindrical structure in which a plurality of filtering holes 4, 4, ... Is formed in a peripheral wall 3.
Is installed. An annular cutter accommodating portion 9 is formed along the inner circumference of the peripheral wall 3, and an annular cutter 10 is rotatably accommodated in the cutter accommodating portion 9.

The annular cutter 10 has an upper ring 11 and
The lower ring 12 and a plurality (for example, four) of cutter plates 13 are provided, and these three members 11, 12, and 13 are integrally connected. Further, as shown in FIG. 4, the cutter plate 13 has a pressure receiving surface 13A that is inclined (inclination angle θ) with respect to the axis C, and as shown in FIG. 3, each blade edge 13a has a suction bell. It is close to the inner peripheral surface of the peripheral wall 3 of 1.

On the other hand, the impeller 1 is penetrated through the discharge bowl 6.
A balance hole 7 for leading out a part of the discharge water discharged from is provided, and the balance hole 7 and the cutter accommodating portion 9 communicate with each other through a communication pipe 14. That is, the outlet of the communication pipe 14 whose inlet is connected to the balance hole 7 is connected to the upper part of the cutter housing 9 by opening downward.

With such a configuration, when the multistage vertical pump P is in operation, part of the discharge water discharged from the impeller 8 to the discharge bowl 6 is led out from the balance hole 7 and passes through the communication pipe 14. It enters the upper part of the annular cutter accommodating portion 9 and ejects downward. As shown in FIG. 4, the discharge water W jetted downward is loaded on the inclined pressure receiving surface 13A of the cutter plate 13 to move the annular cutter 10 in the arrow X direction. That is, the annular cutter 10 is rotated in the arrow X direction in the annular cutter accommodating portion 9. Since the cutting edge 13a of each cutter plate 13 is close to the inner peripheral surface of the peripheral wall 3 of the suction bell 1, even if an elongated foreign object enters the filter holes 4, 4 ... 13 each cutting edge 13
It can be cut by a. Therefore, it is possible to prevent a decrease in the opening ratio due to clogging of the filter holes 4, 4 ..., and to prevent the pumping performance from being adversely affected so that the pump performance is not adversely affected. Moreover, since a part of the discharge water discharged into the discharge bowl 6 is effectively used as the rotational energy of the annular cutter 10, it is not necessary to separately install a drive mechanism for the annular cutter 10. Therefore, the complexity of the structure and the increase in cost can be avoided.

In the above-described embodiment, the structure applied to the multi-stage vertical shaft pump P has been described, but it may be applied to the single-stage vertical shaft pump P. Further, although the configuration in which one balance hole 7 is provided has been described, a plurality of balance holes 7 are provided and the balance holes 7 are communicated with the annular cutter accommodating portion 9 through the same number of communication pipes 14. You may comprise. Further, the application of the present invention is not limited to the vertical shaft pump P described in the above embodiment, but can be applied to other centrifugal pumps.

[0014]

As described above, according to the present invention, a part of the discharge water discharged from the impeller to the discharge bowl is led out from the balance hole and is jetted in the annular cutter accommodating portion through the communication pipe, thereby making the cutter plate. Since the annular cutter is loaded on the inclined pressure receiving surface of the to rotate the annular cutter in the annular cutter accommodating section, it is possible to avoid complicated structure and cost increase without installing a separate drive mechanism for the annular cutter. , Cutting the slender foreign matter that has entered the filter hole,
It is possible to prevent a reduction in the opening ratio due to the clogging of the filter holes, and to prevent the pumping performance from being adversely affected by reducing the pumping amount.

[Brief description of drawings]

FIG. 1 is a sectional view showing a multistage vertical shaft pump to which the present invention is applied.

FIG. 2 is an enlarged cross-sectional view showing a main part of FIG.

FIG. 3 is a bottom view of the annular cutter.

FIG. 4 is a front view of an annular cutter.

FIG. 5 is a cross-sectional view of a conventional example.

[Explanation of symbols]

 1 suction bell 2 suction strainer 3 peripheral wall 4 filtration hole formed in peripheral wall 7 balance hole 8 impeller 9 annular cutter housing 10 annular cutter 13 cutter plate 13A pressure receiving surface of cutter plate 14 communication pipe C axis P vertical shaft pump (pump) W Part of discharge water θ Inclination angle of pressure receiving surface of cutter plate

Claims (1)

[Claims] 1. A suction strainer having a bottomed tubular structure, which is attached to a lower end of a suction bell of a pump and has a plurality of filtration holes formed in a peripheral wall, wherein an annular cutter accommodating portion is formed along an inner circumference of the peripheral wall, An annular cutter having a cutter plate having a pressure receiving surface inclined with respect to the axis is rotatably accommodated in the cutter accommodating portion, and a balance hole for discharging a part of discharge water discharged from the impeller is provided. A communication pipe is provided which connects the balance hole and the cutter accommodating portion, and ejects the discharged discharge water downward from the upper portion of the cutter accommodating portion to load the pressure receiving surface. Suction strainer for vertical shaft pumps.