JP6997641B2 - Pump with vortex suppressor - Google Patents

Description

The present invention relates to a pump used for pumping water in a suction water tank, and more particularly to a pump provided with a vortex suppressing device for suppressing the generation of an air suction vortex.

In pump equipment that drains rivers and sewage, the pump is required to operate at a lower water level due to unequal subsidence over time such as inflow channels in areas subject to inundation countermeasures on the upstream side. In addition, as a countermeasure against sudden rainfall such as the recent guerrilla rainstorm, improvement of the pumping capacity of the pump is also required.

However, at the suction port of the pump, a vortex may be generated on the free surface of the water in the suction water tank as the water level drops (the water surface becomes closer to the suction port). When the vortex is drawn into the pump, it becomes an air suction vortex, and air enters the inside of the pump. As a result, abnormal vibration of the pump may be caused and the pump may fail. Therefore, to prevent inhalation of air, lower the bottom level of the suction water tank, lower the position of the suction port of the pump, set a limit on the water absorption level, and do not operate the pump below that water level. Has been done conventionally.

However, the method of lowering the bottom level of the suction water tank increases the civil engineering work cost and the construction cost. In addition, when repairing the existing pump equipment, the construction period became long, and it was practically impossible to repair the existing pump equipment including civil engineering work while operating the pump equipment. Further, when the suction port approaches the bottom surface of the suction water tank, an underwater vortex from the bottom surface or the side wall of the suction water tank is likely to be generated.

As another vortex prevention measure, a tubular member having a large number of holes is arranged around the pump suction pipe (see Patent Document 1), or a suction cylinder that opens in the horizontal direction is connected to the suction port of the pump (see Patent Document 1). Various attempts have been made such as (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2001-41200 Japanese Unexamined Patent Publication No. 2000-97199

Patent Document 1 has a structure in which water flows into a small gap or hole. For this reason, dust such as branches, grass, and cloth contained in river water or sewage, which is the water handled in ordinary pump equipment, gets entangled in the gaps and holes and closes these gaps or holes. If the gap or hole is closed, the vortex prevention function cannot be secured, and in the worst case, the suction function of the pump is also affected. As a result, satisfactory pump operation cannot be performed (rated drainage operation cannot be performed), which may cause flood damage.

In Patent Document 2, since the suction port is covered with a cylinder, the suction loss of the pump becomes large. That is, there is a problem that the drainage performance of the pump is deteriorated by causing a pipe loss or a decrease in efficiency.

The present invention has been made in view of the above-mentioned conventional problems, and to provide a pump capable of effectively suppressing the generation of an air suction vortex in a suction water tank without impairing the suction performance of the pump. With the goal.

In order to achieve the above-mentioned object, one aspect of the present invention is a pump for pumping water in a suction tank, the main shaft extending in the vertical direction, an impeller fixed to the main shaft, and the impeller inside. A pump casing to be accommodated and a semi-annular inclined plate fixed to the outer peripheral surface of the pump casing are provided, and the semi-annular inclined plate is arranged on the downstream side of the main shaft with respect to the flow direction of water in the suction water tank. Moreover, when viewed from the axial direction of the main shaft, it is located inside the opening formed in the pump installation floor, and the semi-annular inclined plate is inclined upward with respect to the horizontal direction, and the semi-annular is formed. The pump is characterized in that the upward inclination angle of the inclined plate with respect to the horizontal direction is 30 ° to 60 ° .

A preferred embodiment of the present invention is characterized in that the angle formed by the two lines connecting the axial center of the main shaft and both side edges of the semi-annular inclined plate is 120 ° to 180 °.
In a preferred embodiment of the present invention, the semi-annular inclined plate includes a first semi-annular inclined plate and a second semi-annular inclined plate separated from each other, and the first semi-annular inclined plate and the second semi-annular inclined plate are provided. The semi-annular inclined plate is characterized in that it is arranged symmetrically with respect to a straight line parallel to the flow direction of the water passing through the axis of the main axis.
A preferred embodiment of the present invention is characterized in that the pump casing includes a suction bell mouth having a suction port opened downward, and the semi-annular inclined plate is fixed to the lower end of the suction bell mouth.
In a preferred embodiment of the present invention, the pump casing includes a suction bell mouth having a suction port opened downward, the semi-annular inclined plate is a plurality of semi-annular inclined plates, and the plurality of semi-annular inclined plates are a plurality of semi-annular inclined plates. The semi-annular inclined plates are arranged apart from each other in the vertical direction, and one of the plurality of semi-annular inclined plates is fixed to the lower end of the suction bell mouth.
A preferred embodiment of the present invention further comprises a plurality of vertical bars and a plurality of vertical ribs arranged outside the pump casing, wherein the plurality of vertical bars and the plurality of vertical ribs flow water in the suction water tank. The plurality of vertical bars are arranged on the downstream side of the main shaft in the direction and above the semi-annular inclined plate, and the plurality of vertical bars are in a state where a gap exists between the outer peripheral surface of the pump casing and the pump casing. The plurality of vertical ribs are fixed to the outer peripheral surface of the pump casing, and the plurality of vertical bars and the plurality of vertical ribs are pumps when viewed from the axial direction of the main shaft. It is located inside an opening formed in the installation floor, and the plurality of vertical bars are arranged adjacent to each of the plurality of vertical ribs.

The semi-annular inclined plate is provided on the downstream side of the main shaft, and can suppress the generation of an air suction vortex without causing a suction loss and reducing the pumping capacity of the pump. Further, since the semi-annular inclined plate is installed in the pump casing, it is not necessary to fasten it to the suction water tank, and it is not necessary to reinforce the suction water tank.

It is a schematic diagram which shows one Embodiment of the pump provided with the vortex suppression device. It is a figure which shows the Karman vortex generated on the downstream side of a pumping pipe. It is a figure which shows the example of each dimension associated with a pump diameter. It is the figure which looked at the pump and the suction water tank shown in FIG. 3 from the top. It is a side view which shows the semi-annular inclined plate as an air suction vortex suppressing device. FIG. 5 is a cross-sectional view taken along the line AA of FIG. It is a figure which shows the flow from Karman vortex to the suction port. It is a top view which shows the other embodiment of a pump. It is a side view which shows still another embodiment of a pump. 9 is a cross-sectional view taken along the line BB of FIG. It is a side view which shows still another embodiment of a pump. 11 is a cross-sectional view taken along the line CC of FIG. It is a figure which shows the flow of the water which was divided by a pump casing or a pumping pipe. It is a figure which looked at the plurality of underwater vortex suppression plates shown in FIG. 1 from the bottom.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Although the embodiments described below relate to vertical shaft pumps, the present invention is not limited to these embodiments and can also be used for horizontal shaft pumps. Further, the present invention can also be used for a column pipe type submersible pump. FIG. 1 is a schematic view showing an embodiment of a pump provided with a vortex suppression device. As shown in FIG. 1, the pump 20 is connected to a main shaft 32 extending in the vertical direction, an impeller 31 fixed to the main shaft 32, a pump casing 27 accommodating the impeller 31 inside, and the upper end of the pump casing 27. A pumping pipe 28 is provided, and a discharge curved pipe 30 connected to the upper end of the pumping pipe 28 is provided. The pump casing 27 is suspended in the suction water tank 1 by a pumping pipe 28. The pump casing 27 includes a suction bell mouth 22, an impeller casing 21, and a discharge bowl 24. The upper end of the discharge bowl 24 is connected to the lower end of the pumping pipe 28. The suction bell mouth 22 has a suction port 22a that opens downward. The upper end of the suction bell mouth 22 is connected to the lower end of the impeller casing 21. The impeller 31 is housed in the impeller casing 21 and the discharge bowl 24.

The pumping pipe 28 extends downward through an opening 5 formed in the pump installation floor 2 constituting the upper wall of the suction water tank 1. A hanging pipe 33 is fixed to the upper end of the pumping pipe 28. The suspension pipe 33 is fixed to the pump base 35 installed on the pump installation floor 2. The pumping pipe 28 is fixed to the pump installation floor 2 via the hanging pipe 33 and the pump base 35. The spindle 32 extends vertically through the discharge curved pipe 30, the pumping pipe 28, and the pump casing 27, and the lower end thereof is located in the pump casing 27.

The spindle 32 is rotatably supported by an outer bearing 45 and an underwater bearing 41. The outer bearing 45 is fixed to the upper part of the discharge curved pipe 30 and supports the upper part of the spindle 32. The underwater bearing 41 is housed in the discharge bowl 24 and supports the lower part of the spindle 32. An inner bowl 25 is arranged inside the discharge bowl 24, and the inner bowl 25 is connected to the discharge bowl 24 by a plurality of guide vanes 37. The underwater bearing 41 is fixed to the inner peripheral surface of the inner bowl 25 via the support member 41a.

The main shaft 32 projects upward from the discharge curved pipe 30 and is connected to a prime mover (for example, a motor) (not shown). The main shaft 32 and the impeller 31 are configured to rotate by this prime mover. The plurality of guide vanes 37 are arranged above the impeller 31 (discharge side). A water flow path is formed between the inner peripheral surface of the discharge bowl 24 and the outer peripheral surface of the inner bowl 25. When the impeller 31 rotates, the water in the suction water tank 1 is sucked from the suction port 22a of the suction bell mouth 22. The water is transferred to a discharge pipe (not shown) through the discharge bowl 24, the pumping pipe 28, and the discharge curved pipe 30 by the rotation of the impeller 31.

The pump 20 further includes a semi-annular inclined plate 71 as an air suction vortex suppressing device for suppressing the generation of an air suction vortex. The semi-annular inclined plate 71 is fixed to the outer peripheral surface of the pump casing 27, and is arranged on the downstream side of the main shaft 32 with respect to the flow direction of water in the suction water tank 1. In the embodiment shown in FIG. 1, the semi-annular inclined plate 71 is fixed to the lower end of the suction bell mouth 22 on the downstream side of the main shaft 32 with respect to the flow direction of water in the suction water tank 1. The semi-annular inclined plate 71 is located inside the opening 5 formed in the pump installation floor 2 when viewed from the axial direction of the main shaft 32. Therefore, when performing maintenance or repair of the pump 20, the entire pump 20 can be pulled up through the opening 5.

As the pumping capacity of the pump 20 is improved, the flow velocity of the water channel of the suction water tank 1 becomes higher, and as a result, an underwater vortex is likely to be generated from the bottom surface of the suction water tank 1. Therefore, the pump 20 according to the embodiment shown in FIG. 1 is a plurality of underwater vortex suppressing devices for suppressing the underwater vortex generated between the suction bell mouth 22 and the bottom surface of the suction water tank 1 at the lower part of the suction bell mouth 22. The underwater vortex suppressing plate 49 is provided. The underwater vortex suppressing plate 49 is a flat plate-shaped member.

As shown in FIG. 2, the air suction vortex is generated by the development of the Karman vortex 7 generated when the flow of water forming the free surface is diverted by the pumping pipe 28 or the discharge bowl 24. Therefore, the Karman vortex 7 is generated on the downstream side of the pumping pipe 28 or the discharge bowl 24. Further, the Karman vortex 7 is flowed to the downstream side by the flow of water. Therefore, the semi-annular inclined plate 71 is arranged on the downstream side of the main shaft 32.

FIG. 3 is a diagram showing an example of each dimension associated with the pump diameter, and FIG. 4 is a view of the pump 20 and the suction water tank 1 shown in FIG. 3 as viewed from above. As shown in FIG. 3, assuming that the pump diameter (the diameter on the discharge side of the pump casing 27 in this embodiment) is d, from the lower end of the suction bell mouth 22 (that is, the lower end of the pump casing 27) to the bottom surface of the suction water tank 1. The distance of is 0.5d or more, and is in the range of 0.75d to 1.0d as an example. The distance (hereinafter, rear wall distance) from the center of the pump 20 (axis center O of the main shaft 32) to the rear wall of the suction water tank 1 is 1.5d or less. The diameter of the opening 5 is a value generally determined by the pump diameter d, but is in the range of 1.6d to 2.1d in one embodiment. As shown in FIG. 4, the water channel width of the suction water tank 1 is about 3.0 d. When designed with these dimensions, the minimum water level LWL of the suction water tank 1 in which the pump 20 can be operated can be lowered by about 0.5d to 0.9d as compared with the conventional pump.

FIG. 5 is a side view showing a semi-annular inclined plate 71 as an air suction vortex suppressing device, and FIG. 6 is a cross-sectional view taken along the line AA of FIG. In FIG. 5, the illustration of the plurality of underwater vortex suppression plates 49 is omitted. As shown in FIGS. 5 and 6, the semi-annular inclined plate 71 has a semi-annular shape, and its inner peripheral surface is fixed to the outer peripheral surface of the pump casing 27. In the embodiment shown in FIGS. 5 and 6, the semi-annular inclined plate 71 is fixed to the lower end of the suction bell mouth 22 on the downstream side of the main shaft 32 with respect to the flow direction of water in the suction water tank 1. The fixed position of the semi-annular inclined plate 71 is not limited to this embodiment.

In the embodiment shown in FIGS. 5 and 6, the angle θ0 formed by the two lines connecting the axis O of the main shaft 32 and both side edges of the semi-annular inclined plate 71 is 180 °, but the above-mentioned angle θ0 is 180 °. It is not limited to, and may be selected within the range of 120 ° to 180 °. The semi-annular inclined plate 71 is provided so as to be inclined upward with respect to the horizontal direction. In one example, the angle of inclination of the semi-annular inclined plate 71 upward with respect to the horizontal direction is 30 ° to 60 °. The semi-annular inclined plate 71 may be integrally formed with the suction bell mouth 22.

When the Karman vortex 7 is generated, a strong downward flow from the Karman vortex 7 toward the suction port 22a is generated at the time of pumping and develops into an air suction vortex. FIG. 7 is a diagram showing a flow from the Karman vortex 7 toward the suction port 22a. In FIG. 7, the illustration of the plurality of underwater vortex suppression plates 49 is omitted. As shown in FIG. 7, the semi-annular inclined plate 71 is arranged at a position that obstructs the course of the downward flow F1 from the Karman vortex 7 toward the suction port 22a. The downward flow F1 from the Karman vortex 7 toward the suction port 22a is disturbed by the flow F2 from the semi-annular inclined plate 71 and pushed outward in the radial direction of the pump casing 27. In this way, the semi-annular inclined plate 71 can disturb and obstruct the strong downward flow in the process of developing from the Karman vortex 7 to the air suction vortex 7. As a result, the semi-annular inclined plate 71 can suppress the generation of an air suction vortex.

FIG. 8 is a top view showing another embodiment of the pump 20. The semi-annular inclined plate 71 of the present embodiment is composed of a first semi-annular inclined plate 71A and a second semi-annular inclined plate 71B separated from each other. The configuration of the present embodiment, which is not particularly described, is the same as that of the embodiments described with reference to FIGS. 1 to 7, and therefore the overlapping description thereof will be omitted. The circumferential lengths of the semi-annular inclined plates 71A and 71B of the present embodiment are shorter than the circumferential lengths of the semi-annular inclined plates 71 described with reference to FIGS. 5 and 6. In the embodiment shown in FIG. 8, the semi-annular inclined plates 71A and 71B are fixed to the lower end of the suction bell mouth 22 on the downstream side of the main shaft 32 with respect to the flow direction of water in the suction water tank 1. The fixed position of the semi-annular inclined plate 71 is not limited to this embodiment.

The first semi-annular inclined plate 71A and the second semi-annular inclined plate 71B are straight lines that are downstream of the main shaft 32 with respect to the water flow direction and parallel to the water flow direction passing through the axis O of the main shaft 32. They are arranged symmetrically with respect to RL. Specifically, the first semi-annular inclined plate 71A and the second semi-annular inclined plate 71B are at an angle of 45 ° with respect to a straight line RL parallel to the flow direction of water passing through the axis O of the main shaft 32. , And are arranged on straight lines L1 and L2 passing through the axis O of the main shaft 32.

It is known that the Karman vortex 7 is generated at an angle of about 45 ° with respect to a straight line parallel to the flow direction of water passing through the axis O of the main shaft 32 when the rear wall distance is 1.5 d or less. The first semi-annular inclined plate 71A and the second semi-annular inclined plate 71B are arranged on the straight lines L1 and L2, respectively, in order to obstruct the course of the downward flow F1 from the Karman vortex 7 to the suction port 22a. There is. The semi-annular inclined plates 71A and 71B of the present embodiment have a compact structure and can suppress the generation of an air suction vortex.

As shown in FIG. 8, the straight line L10 is a straight line connecting the axial center O of the main shaft 32 and the upstream side edge 72A of the first semi-annular inclined plate 71A, and the straight line L20 is the axial center O of the main shaft 32 and the first. It is a straight line connecting the upstream side edge 72B of the semi-annular inclined plate 71B of 2. In FIG. 8, the angle θ1 formed by the straight line L10 and the straight line L20 is 180 °, but the angle θ1 may be selected within the range of 120 ° to 180 °. That is, the angle θ1 formed by L10 and L20 is the angle formed by the two lines connecting the axial center O of the main shaft 32 and both side edges of the semi-annular inclined plate 71. The first semi-annular inclined plate 71A and the second semi-annular inclined plate 71B are provided so as to be inclined upward with respect to the horizontal direction. In one example, the upward tilt angle of the first semi-annular tilt plate 71A and the second semi-annular tilt plate 71B with respect to the horizontal direction is 30 ° to 60 °. The first semi-annular inclined plate 71A and the second semi-annular inclined plate 71B may be formed integrally with the suction bell mouth 22.

9 is a side view showing still another embodiment of the pump 20, and FIG. 10 is a cross-sectional view taken along the line BB of FIG. In FIG. 9, the illustration of the plurality of underwater vortex suppression plates 49 is omitted. As shown in FIGS. 9 and 10, the pump 20 of the present embodiment includes a plurality of semi-annular inclined plates 71. The configuration of the present embodiment, which is not particularly described, is the same as that of the embodiments described with reference to FIGS. 1 to 7, and therefore the overlapping description thereof will be omitted. Each of the plurality of semi-annular inclined plates 71 is fixed to the outer peripheral surface of the pump casing 27, and is arranged on the downstream side of the main shaft 32 with respect to the flow direction of water in the suction water tank 1. The plurality of semi-annular inclined plates 71 are arranged so as to be separated from each other along the vertical direction. The plurality of semi-annular inclined plates 71 are located inside the opening 5 formed in the pump installation floor 2 when viewed from the axial direction of the main shaft 32.

The pump 20 of the present embodiment includes two semi-annular inclined plates 71, and one of the two semi-annular inclined plates 71 is located on the downstream side of the main shaft 32 with respect to the flow direction of water in the suction water tank 1. It is fixed to the lower end of the suction bell mouth 22. The other one of the two semi-annular inclined plates 71 is fixed to the lower end of the discharge bowl 24. If the distance from the water surface to the semi-annular inclined plate 71 becomes large due to the rise in the water level of the suction water tank 1, it may not be possible to effectively disturb the downward flow from the Karman vortex 7 to the suction port 22a. By arranging the plurality of semi-annular inclined plates 71 at different positions in the vertical direction, the distance from the water surface to the semi-annular inclined plate 71 does not increase even when the water level of the suction water tank 1 changes, and the suction water tank 1 has a wide range. The generation of air suction vortices can be suppressed at the water level.

The pump 20 of the present embodiment includes two semi-annular inclined plates 71, but the number of semi-annular inclined plates 71 is not limited to this embodiment, and three or more semi-annular inclined plates 71 are inclined at different positions in the vertical direction. A plate 71 may be provided. Further, in the present embodiment, one of the two semi-annular inclined plates 71 is fixed to the lower end of the suction bell mouth 22, and the other one of the two semi-annular inclined plates 71 is discharged. Although it is fixed to the lower end of the bowl 24, the fixing position of the semi-annular inclined plate 71 is not limited to this embodiment. The plurality of semi-annular inclined plates 71 may be integrally formed with the pump casing 27.

In one embodiment, each of the plurality of semi-annular tilt plates 71 described with reference to FIGS. 9 and 10 is the first semi-annular tilt plate 71A and the second semi-annular tilt plate 71A and the second, respectively, which are separated from each other as described with reference to FIG. It may be composed of a semi-annular inclined plate 71B. The configuration of the present embodiment, which is not particularly described, is the same as that of the embodiment described with reference to FIG. 8, and therefore the overlapping description thereof will be omitted.

11 is a side view showing still another embodiment of the pump 20, and FIG. 12 is a sectional view taken along the line CC of FIG. The configuration of the present embodiment, which is not particularly described, is the same as that of the embodiments described with reference to FIGS. 1 to 7, and therefore the overlapping description thereof will be omitted. In FIG. 11, the illustration of the plurality of underwater vortex suppression plates 49 is omitted. As shown in FIGS. 11 and 12, the pump 20 of the present embodiment further includes a plurality of vertical bars 61 and a plurality of vertical ribs 62 as an air suction vortex suppressing device.

The vertical rod 61 and the vertical rib 62 are arranged outside the pump casing 27 and above the semi-annular inclined plate 71. When viewed from the axial direction of the main shaft 32, the vertical bar 61 and the vertical rib 62 are located inside the opening 5. Therefore, when performing maintenance or repair of the pump 20, the entire pump 20 can be pulled up through the opening 5. The vertical rod 61 and the vertical rib 62 are arranged on the downstream side of the main shaft 32 with respect to the flow direction of water in the suction water tank 1. In the present embodiment, two vertical bars 61 and two vertical ribs 62 are provided, but the number of vertical bars 61 and vertical ribs 62 is not limited to this embodiment.

Each vertical bar 61 generally has a circular cross-sectional shape and extends along the spindle 32 as a whole. Similarly, each vertical rib 62 extends along the spindle 32 as a whole. The vertical bar 61 and the vertical rib 62 extend in the vertical direction as a whole, and a part of them may be curved. Each vertical bar 61 is connected to the outer peripheral surface of the pump casing 27 by a plurality of brackets 65. That is, each vertical bar 61 is fixed to the pump casing 27 in a state where a gap exists between the vertical bar 61 and the outer peripheral surface of the pump casing 27. In one embodiment, the upper portion of the vertical bar 61 may be fixed to the pumping pipe 28. According to the example of each dimension shown in FIG. 3, the upper end of the vertical bar 61 is located within the range of 0.5d to 1.5d from the lower end of the suction bell mouth 22. The lower end of the vertical bar 61 is located below the upper end of the impeller 31.

As described above, as the water level of the suction water tank 1 drops, Karman vortices 7 (see FIG. 2) may be generated on the free surface of the suction water tank 1. In order to prevent the generation of the Karman vortex 7, the upper end of the vertical bar 61 needs to be located above the water level of the suction water tank 1 when the Karman vortex 7 is generated. The minimum water level LWL of the pump is generally a water level of 2.5 d or higher. At a water level higher than this minimum water level LWL, the Karman vortex 7 generally does not occur. Since the pump 20 operates even at a water level lower than the normal minimum water level LWL, the upper end of the vertical bar 61 is at a position below the normal minimum water level LWL. According to FIG. 3, since the distance from the lower end of the suction bell mouth 22 to the bottom surface of the suction water tank 1 is within the range of 0.75d to 1.0d, the upper end of the vertical bar 61 is the lower end of the suction bell mouth 22. It is located within the range of 0.5d to 1.5d.

The vertical rib 62 has a curved shape along the outer peripheral surface of the pump casing 27 and extends in the axial direction of the main shaft 32. The vertical rib 62 is fixed to the outer peripheral surface of the pump casing 27, and projects outward from the outer peripheral surface of the pump casing 27 in the radial direction. In one embodiment, the upper portion of the vertical rib 62 may be fixed to the outer peripheral surface of the pumping pipe 28. Further in one embodiment, the longitudinal rib 62 may be integrally formed with the pump casing 27 and / or the pumping pipe 28.

The two vertical bars 61 are arranged adjacent to each of the two vertical ribs 62. Each vertical bar 61 is located at a position farther from the axis O of the main shaft 32 than the adjacent vertical rib 62. That is, the distance between the axis O of the spindle 32 and the vertical bar 61 is longer than the distance between the axis O of the spindle 32 and the vertical rib 62. Similar to the vertical bar 61, the upper end of the vertical rib 62 needs to be located above the water level of the suction water tank 1 when the Karman vortex 7 is generated. In the embodiment shown in FIG. 11, the vertical rib 62 is shorter than the vertical bar 61, but in one embodiment, the vertical rib 62 may have the same length as the vertical bar 61 or may be longer than the vertical bar 61. ..

The two vertical bars 61 are located on the downstream side of the main shaft 32 with respect to the flow direction of water in the suction water tank 1, and are arranged symmetrically with respect to a straight line RL parallel to the flow direction of water passing through the axis O of the main shaft 32. ing. Similarly, the two vertical ribs 62 are located downstream of the spindle 32 with respect to the water flow direction and are arranged symmetrically with respect to a straight line RL parallel to the water flow direction through the axis O of the spindle 32. .. In the embodiment shown in FIGS. 11 and 12, the two vertical bars 61 and the two vertical ribs 62 are arranged downstream of the separation point of the water flow on the outer peripheral surface of the pump casing 27.

When the water level of the suction water tank 1 is high, the flow velocity of the water in the suction water tank 1 is low, and when the water level of the suction water tank 1 is low, the flow velocity of the water in the suction water tank 1 is high. The location where the Karman vortex 7 is generated changes depending on the water level of the suction water tank 1 and the flow velocity of the water in the suction water tank 1 at the time of pumping. The Karman vortex 7 is generated near the outer peripheral surface of the pump casing 27 or the pumping pipe 28 when the flow velocity of the water in the suction water tank 1 is low.

FIG. 13 is a diagram showing the flow of water separated by the pump casing 27 or the pumping pipe 28. As shown by the arrow in FIG. 13, the water in the vicinity of the outer peripheral surface of the pump casing 27 or the pumping pipe 28 divided by the pump casing 27 or the pumping pipe 28 is disturbed by colliding with the vertical rib 62. As a result, the vertical rib 62 can suppress the generation of Karman vortices 7 in the vicinity of the outer peripheral surface of the pump casing 27 or the pumping pipe 28.

The vertical rib 62 can effectively suppress the generation of an air suction vortex when the water level of the suction water tank 1 is high (when the flow velocity of the water in the suction water tank 1 is low). As an example, the vertical rib 62 has a height (length in the radial direction of the pump casing 27) of 0.1 d or more and a width thereof (length in the circumferential direction of the pump casing 27) of 0.1 d or less. At some point, the generation of Karman vortices 7 can be effectively suppressed.

The water that collides with the vertical rib 62 and disturbs its flow may flow to the outside of the pump casing 27 and generate a Karman vortex 7 at a position away from the pump casing 27. Further, it has been experimentally confirmed that when the water level of the suction water tank 1 is relatively low (when the flow velocity of the water in the suction water tank 1 is high), the Karman vortex 7 is likely to be generated at a position away from the pump casing 27. Therefore, in order to suppress the generation of such Karman vortices 7, in the present embodiment, the vertical bars 61 are arranged outside the vertical ribs 62 in the radial direction. As shown by the arrow in FIG. 13, the water that collided with the vertical rib 62 and flowed to the outside of the pump casing 27 and a part of the water that was separated by the pump casing 27 or the pumping pipe 28 collided with the vertical rod 61. However, the flow is disturbed. As a result, the vertical bar 61 can suppress the generation of Karman vortices 7 at a position away from the pump casing 27.

The vertical bar 61 is provided when the water level in the suction water tank 1 is further lowered from the water level range of the suction water tank 1 in which the vertical rib 62 can suppress the generation of an air suction vortex (that is, the flow velocity of the water in the suction water tank 1 is increased. When it is high), the generation of air suction vortices can be effectively suppressed. Further, the Karman vortex 7 generated by the water colliding with the vertical rib 62 and flowing to the outside of the pump casing 27 is generated on the downstream side of the vertical rib 62. Therefore, the vertical bar 61 is arranged on the downstream side (see FIG. 12) of the extension line of the line connecting the axial center O of the main shaft 32 and the vertical rib 62. In one embodiment, the vertical bar 61 may be arranged on the extension line.

Is the angle θ2 formed by the two lines connecting the axis O of the spindle 32 and the two vertical ribs 62 larger than the angle θ3 formed by the two lines connecting the axis O of the spindle 32 and the two vertical bars 61? , Or equal (θ2 ≧ θ3). In the embodiment shown in FIG. 12, the angle θ2 is larger than the angle θ3. When the values of θ2 and θ3 are 30 ° to 120 °, the combination of the vertical rib 62 and the vertical bar 61 can effectively suppress the generation of the Karman vortex 7.

In the embodiment shown in FIGS. 11 and 12, a part of the vertical bar 61 is curved along the outer peripheral surface of the pump casing 27, but the shape of the vertical bar 61 is not limited to this embodiment. In one embodiment, the vertical bar 61 may have a linear shape extending parallel to the spindle 32. Further, in one embodiment, the cross-sectional shape of the vertical bar 61 may be a polygon such as a quadrangle or an L-shape. The vertical rib 62 of the present embodiment has a quadrangular cross-sectional shape, but the cross-sectional shape of the vertical rib 62 is not limited to this shape. In one embodiment, the cross-sectional shape of the vertical rib 62 may be triangular or circular.

The combination of the plurality of vertical bars 61 and the plurality of vertical ribs 62 can suppress the generation of Karman vortices 7 and suppress the generation of air suction vortices at a wide water level and a wide flow velocity in the suction water tank 1. By combining the semi-annular inclined plate 71 with the combination of the plurality of vertical bars 61 and the plurality of vertical ribs 62, the generation of the air suction vortex can be suppressed more effectively.

In one embodiment, the semi-annular sloping plate 71 described with reference to FIGS. 11 and 12 is the first semi-annular sloping plate 71A and the second semi-annular sloping plate 71 that are separated from each other as described with reference to FIG. It may be composed of 71B. Further, in one embodiment, the pump 20 described with reference to FIGS. 11 and 12 may include a plurality of semi-annular inclined plates 71 described with reference to FIGS. 9 and 10.

According to each of the above-described embodiments, there is substantially nothing that obstructs the flow of water toward the suction port 22a of the suction bell mouth 22, and there is almost no suction loss. 20 can suppress the generation of an air suction vortex without deteriorating the pumping capacity. Further, since the air suction vortex suppressing device of each of the above-described embodiments is installed in the pump casing 27, it is not necessary to fasten it to the suction water tank 1, and it is not necessary to reinforce the suction water tank 1.

FIG. 14 is a view of the plurality of underwater vortex suppression plates 49 shown in FIG. 1 as viewed from below. As shown in FIG. 14, in the present embodiment, four underwater vortex suppressing plates 49 are fixed to the lower part of the suction bell mouth 22. Two of the four underwater vortex suppression plates 49 are arranged parallel to the water flow direction in the suction water tank 1, and the other two are arranged perpendicular to the water flow direction in the suction water tank 1. However, the number of underwater vortex suppression plates 49 is not limited to this embodiment.

One end of each of the plurality of underwater vortex suppression plates 49 is fixed to each other on an extension line of the axis O of the main shaft 32, and the other end of each of the plurality of underwater vortex suppression plates 49 is the inner peripheral surface of the suction bell mouth 22. It is fixed to. As shown in FIG. 1, the underwater vortex suppressing plate 49 projects downward from the lower end of the suction bell mouth 22. The upper end of the underwater vortex suppressing plate 49 is located higher than the lower end of the suction bell mouth 22 and lower than the impeller 31.

According to such an underwater vortex suppressing plate 49, the underwater vortex generated between the suction bell mouth 22 and the bottom surface of the suction water tank 1 can be suppressed. This underwater vortex is formed by developing a swirling flow between the suction bell mouth 22 and the bottom surface of the suction water tank 1, and when the suction bell mouth 22 is located near the bottom surface of the suction water tank 1. It is easy to occur in. The pump 20 of the present embodiment can effectively suppress the generation of the underwater vortex by eliminating the swirling flow that causes the underwater vortex with the underwater vortex suppressing plate 49. Therefore, the suction bell mouth 22 can be arranged at a lower position than the conventional structure, and the water can be pumped at a low water level. Since the submersible vortex suppressing plate 49 of the present embodiment can be attached to the pump 20, it is not necessary to fix it to the suction water tank 1 which is a civil engineering frame, and it is possible to provide a low-cost and highly reliable pump.

The air suction vortex suppressing device (semi-annular inclined plate 71, vertical bar 61, and vertical rib 62) and the underwater vortex suppressing plate 49 of each of the above-described embodiments are of an impeller as shown in Japanese Patent Application Laid-Open No. 2007-285253. It may be applied to a pump in which a submersible bearing is arranged below.

The above-described embodiments have been described for the purpose of allowing a person having ordinary knowledge in the technical field to which the present invention belongs to carry out the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the invention is not limited to the described embodiments, but is to be construed in the broadest range in accordance with the technical ideas defined by the claims.

1 Suction water tank 2 Pump installation floor 5 Opening 7 Kalman vortex 20 Pump 21 Impeller casing 22 Suction bell mouth 22a Suction port 24 Discharge bowl 25 Inner bowl 27 Pump casing 28 Pumping pipe 30 Discharge curved pipe 31 Impeller 32 Main shaft 33 Suspended pipe 35 Pump base 37 Guide vane 41 Submersible bearing 41a Support member 45 Outer bearing 49 Submersible vortex suppression plate 61 Vertical rod 62 Vertical rib 65 Bracket 71 Semi-annular inclined plate 71A First semi-annular inclined plate 71B Second semi-annular inclined plate 72A Upstream Side edge 72B Upstream side edge

Claims (6)

In the pump that pumps the water in the suction tank,
The spindle extending in the vertical direction and
The impeller fixed to the spindle and
A pump casing that houses the impeller inside,
A semi-annular inclined plate fixed to the outer peripheral surface of the pump casing is provided.
The semi-annular inclined plate is arranged on the downstream side of the main shaft with respect to the flow direction of water in the suction water tank, and is located inside the opening formed in the pump installation floor when viewed from the axial direction of the main shaft. And
The semi-annular inclined plate is inclined upward with respect to the horizontal direction, and is inclined upward .
A pump characterized in that the upward inclination angle of the semi-annular inclined plate with respect to the horizontal direction is 30 ° to 60 ° . The pump according to claim 1 , wherein the angle formed by the two lines connecting the axis of the main shaft and both side edges of the semi-annular inclined plate is 120 ° to 180 °. The semi-annular inclined plate includes a first semi-annular inclined plate and a second semi-annular inclined plate separated from each other, and the first semi-annular inclined plate and the second semi-annular inclined plate are said to have the same. The pump according to claim 1 or 2 , wherein the pump is arranged symmetrically with respect to a straight line parallel to the flow direction of the water passing through the axis of the main shaft. The pump casing includes a suction bell mouth with a suction port that opens downward.
The pump according to any one of claims 1 to 3 , wherein the semi-annular inclined plate is fixed to the lower end of the suction bell mouth. The pump casing includes a suction bell mouth with a suction port that opens downward.
The semi-annular inclined plate is a plurality of semi-annular inclined plates, and the semi-annular inclined plate is a plurality of semi-annular inclined plates.
The plurality of semi-annular inclined plates are arranged so as to be separated from each other along the vertical direction.
The pump according to any one of claims 1 to 3 , wherein one of the plurality of semi-annular inclined plates is fixed to the lower end of the suction bell mouth. Further comprising a plurality of vertical bars and a plurality of vertical ribs arranged on the outside of the pump casing.
The plurality of vertical bars and the plurality of vertical ribs are arranged on the downstream side of the main shaft and above the semi-annular inclined plate with respect to the flow direction of water in the suction water tank.
The plurality of vertical bars are fixed to the pump casing with a gap between them and the outer peripheral surface of the pump casing.
The plurality of vertical ribs are fixed to the outer peripheral surface of the pump casing.
The plurality of vertical bars and the plurality of vertical ribs are located inside an opening formed in the pump installation floor when viewed from the axial direction of the spindle.
The pump according to any one of claims 1 to 5 , wherein the plurality of vertical bars are arranged adjacent to each of the plurality of vertical ribs.

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