JPH0111999Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a mound-shaped pump suction water tank that prevents the generation of air suction vortices.

(Prior Art) In recent years, the capacity of rainwater or sewage drainage pumps has tended to increase, and the pump suction tank in which the suction port of this pump is arranged has also become larger and is required to have a deeper water depth. In addition, in order to reduce the construction cost of the pump suction water tank, it is required to reduce the depth of the water and reduce the amount of civil engineering excavation. Therefore, as shown in Fig. 3, the water depth of the suction water tank 2 where the pump suction port 1 is arranged is made deeper, and the water depth of the water conduit 3 on the upstream side thereof is made shallower.
A mound-shaped pump suction water tank 5 is commonly used in which the bottom surfaces of the pumps are connected by an inclined surface 4 to reduce the amount of civil engineering excavation and the water depth of the suction water tank 2 is increased.

By the way, this mound-shaped pump suction water tank 5
When the water level on the free surface 6 decreases, the diagonally downward flow that flows along the slope 4 has a strong influence, and the fourth
As shown in the figure, air is drawn in from the free surface 6, and this air flows into the suction water tank 2 and is sucked in from the pump suction port 1, causing pump noise and the like.

Therefore, as an example of a device for preventing air entrainment in the mound-shaped pump suction water tank 5,
A device as shown in FIG. 5 (for example, Japanese Patent Publication No. 59-22071) has been proposed. In this device, plate-shaped bodies 7, 7 are installed between a water conduit 3 and a suction water tank 2, submerged in water so as to slope downward in the flow direction. These plate-like bodies 7, 7 increase the flow velocity at the bottom of the suction tank 2, and the pump suction port 1
The purpose is to prevent the generation of air suction vortices by suppressing the generation of swirling flows around the tube.

(Problem to be solved by the invention) The conventional mound-shaped pump suction water tank 5 shown in FIG. . However, in a state where the free surface 6 is located slightly higher than the plate-like bodies 7, 7, the plate-like bodies 7,
Reference numeral 7 denotes a resistor that obstructs the flow of fluid, and the water level before and behind the plate-shaped bodies 7, 7 is higher on the upstream side than on the downstream side. Then, since the fluid rises and flows over the plate-like bodies 7, 7, the fluid suddenly falls from this rise toward the lower water level downstream of the plate-like bodies 7, 7, and as it falls, air is caught in. Further, there is a problem in that a negative pressure is generated immediately downstream of the plate-like bodies 7, 7, and this negative pressure generates a vortex that entrains air.

The purpose of the present invention was to solve the above-mentioned problems with conventional devices of this type.
To provide a mound-shaped pump suction water tank which divides the flow into a flow along a free surface and a flow along an inclined surface, thereby preventing the generation of air suction vortices due to stable flow.

(Means for Solving the Problems) In order to achieve the above object, the mound-shaped pump suction tank of the present invention includes a suction tank in which a pump suction port is arranged, and a suction tank whose water depth is shallower than that of the suction tank. In a mound-shaped pump suction water tank with a water conduit whose bottom surface is connected by an inclined surface,
It is constructed by submerging a beam above the upstream end of the inclined surface and arranging it perpendicular to the direction of the flow, the beam having a downwardly sloping surface facing the downstream side as the lower surface and a horizontal surface as the upper surface.

(Function) A beam whose bottom surface is a downward slope facing the downstream side and whose horizontal surface is a top surface is submerged above the upstream end of the slope and is placed orthogonal to the direction of the flow, so that the flow in the headrace channel is When the fluid reaches the upper end of the slope, the beam separates the flow into a flow along the slope and a flow along the free surface. The negative pressure that tends to occur immediately downstream of the downwardly sloped surface toward the downstream side is suppressed and compensated for by the flow along the horizontal surface and the free surface. Therefore, the fluid flows into the suction tank in a stable flow, does not create an air suction vortex in the fluid flowing into the suction tank, and has a lower free surface water level compared to conventional devices of this type. The pump can be operated stably up to

(Example) Hereinafter, an example of the present invention will be described with reference to FIG. FIG. 1 is a side sectional view of an embodiment of the mound-shaped pump suction tank of the present invention. In FIG. 1, the same members as those in FIGS. 3 to 5 are given the same reference numerals, and redundant explanations will be omitted.

In FIG. 1, the mound-shaped pump suction water tank 10 of the present invention is characterized by a surface 11a that is substantially parallel to the inclined surface 4 and has a downward slope toward the downstream side.
A beam 11 whose lower surface is the horizontal surface 11b and whose upper surface is the horizontal surface 11b,
The reason is that it is submerged above the upstream end of the slope 4 and is arranged perpendicular to the direction of the flow. Note that the beam 11 shown in FIG. 1 is formed by combining a plate-like member arranged substantially parallel to the inclined surface 4 and a plate-like member arranged horizontally, but it is not formed of a member having a wedge-shaped cross section. It's okay. Further, the surface 11a that is substantially parallel to the slope 4 may have a downward slope toward the downstream side so that the flow follows the slope 4, and it is best if the surface 11a is parallel to the slope 4. ,
Of course, they do not have to be exactly parallel.

In such a configuration, when the fluid flowing through the water conduit 3 reaches the upstream end of the inclined surface 4, the inclined surface 4 is formed by the horizontal surface 11b and the surface 11a of the beam 11, which is substantially parallel to the inclined surface 4 and has a downward slope toward the downstream. The flow is divided into a flow 12a along the free surface 6 and a flow 12b along the free surface 6. Here, although the fluid rises and flows over the beam 11, the water level of the fluid that has climbed over the beam 11 does not drop suddenly due to the horizontal surface 11b. Furthermore, the negative pressure that tends to occur immediately downstream of the surface 11a is suppressed and compensated for by the horizontal surface 11b and the flow along the free surface 6 caused by the horizontal surface 11b, and no vortices reaching the free surface 6 are generated. Therefore, the fluid stably flows into the suction tank 2, and air suction vortices are not generated in the fluid flowing into the suction tank 2.

FIG. 2 is an enlarged side sectional view of a main part of another embodiment of the mound-shaped pump suction tank of the present invention. In FIG. 2, the same members as in FIG. 1 and FIGS. 3 to 5 are given the same reference numerals, and redundant explanations will be omitted.

Mound-shaped pump suction water tank 20 shown in Fig. 2
The characteristics of this include a plate-like body 22 in which a beam 21 is arranged horizontally, and a plate-like body 23 that is substantially parallel to the inclined surface 4 and arranged on a downward slope toward the downstream side.
The plate-like bodies 22 are arranged vertically apart from each other by a gap 21c by the rib plates 24, and further arranged horizontally.
A plate-shaped body 2 whose upstream end is arranged parallel to the inclined surface 4
3, and is configured to protrude upstream from the upstream end of No. 3. The beam 21 is submerged in water above the upstream end of the slope 4 and is arranged perpendicular to the flow direction.

In this configuration, the fluid flowing through the water conduit 3 is divided into a flow 12a along the slope 4 by the plate-shaped body 23 arranged parallel to the slope 4, and a flow 12a along the free surface 6 by the plate-shaped body 22 arranged horizontally. accompanying flow 1
2b and the flow 12c further passing through the gap 21c.
It is divided into two parts. The flow 12c passing through the gap 21c does not generate negative pressure on the downstream side of the beam 21, allowing a more stable flow on the downstream side of the beam 21, and the rib plate 24 provides a rectifying effect. . Furthermore, since the upstream end of the plate-like body 22 arranged horizontally projects upstream from the upstream end of the plate-like member 23 arranged parallel to the inclined surface 4, the flow 12a along the inclined surface 4 The flow 12b along the free surface 6 is smoothly divided, and the beam 21
There is no possibility that the flow will become more exciting. Therefore, no air suction vortex is generated.

Thus, there is no air suction vortex in the fluid flowing into the suction water tank 2, and according to the experiments of the applicant of the present invention, the mound type pump suction of the present invention is more effective than the conventional device of this type shown in FIG. The water tanks 10 and 20 are
The pump can be operated stably until the free surface 6 reaches a lower water level.

(Effect of the invention) As explained above, according to the mound-shaped pump suction tank according to the invention, a beam having a downwardly sloped surface facing the downstream side as the lower surface and a horizontal surface as the upper surface is connected to the upstream end of the inclined surface. Since the pipe is submerged above the water and placed perpendicular to the flow direction, when the fluid flowing through the headrace reaches the upstream end of the slope,
The beam divides the flow into the flow along the slope and the flow along the free surface, and the flow stably flows into the suction tank. For this reason, there is no air suction vortex generated in the fluid flowing into the suction tank, and compared to conventional devices of this type, the pump can be operated stably until the free surface reaches a lower water level. It has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view of one embodiment of the mound-shaped pump suction tank of the present invention, and FIG. 2 is an enlarged side view of main parts of another embodiment of the mound-shaped pump suction tank of the present invention. FIG. 3 is a side sectional view of an example of a conventional mound-shaped pump suction tank, and FIG. 4 shows a problem when the water level of the mound-shaped pump suction tank shown in FIG. 3 decreases. FIG. 5 is a side sectional view of another example of a conventional mound-shaped pump suction water tank. 1: Pump suction port, 2: Suction water tank, 3: Conduit, 4: Inclined surface, 5, 10, 20: Mound-shaped pump suction water tank, 6: Free surface, 11, 21:
Beam, 11a: downward slope facing downstream, 1
1b: horizontal surface, 22: horizontally arranged plate-shaped body,
23: A plate-like body arranged parallel to an inclined surface.

Claims (1)

[Claims for Utility Model Registration] (1) A mound-shaped pipe comprising a suction tank in which a pump suction port is arranged, and a water conduit whose water depth is shallower than that of the suction tank and whose bottom surface is connected to the suction tank by an inclined surface. In the pump suction water tank, a beam having a downwardly sloping surface toward the downstream side as the lower surface and a horizontal surface as the upper surface is submerged in water above the upstream end of the sloping surface and is arranged perpendicular to the flow direction. A mound-shaped pump suction tank. (2) The utility model according to claim 1, characterized in that the beam is formed by vertically separating a horizontal plate-like body and a downwardly sloped plate-like body toward the downstream side. Mound-shaped pump suction tank. (3) Utility model registration claim 2, characterized in that the upstream end of the horizontal plate-like body projects toward the downstream side from the upstream end of the downwardly sloped plate-like body. The mound-shaped pump suction tank shown.