JP3762905B2 - Drainage facility using horizontal pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drainage facility using a horizontal axis pump.
[0002]
[Prior art]
Conventionally, there is a drainage facility shown in FIG. 4 as a drainage facility using a horizontal shaft pump that is installed as a single straight water channel and is called a cylindrical pump (tubular pump). Such a drainage facility using the horizontal axis pump 1 is suitable for flood drainage, sewage stormwater drainage, farmland drainage, and the like, and a drive unit such as an electric motor or gear reducer (not shown) has a horizontal axis C. It is installed in a cylindrical pump casing 2. The outer shape of the horizontal axis pump 1 has a straight cylindrical shape on the horizontal axis C from the one end suction port 3 to the other end discharge port 4. The suction port 3 faces the suction water tank 5, and discharges it. The outlet 4 faces the discharge water tank 6 and includes an axial flow impeller or a mixed flow impeller (not shown) driven by the drive unit (see, for example, Non-Patent Document 1).
[0003]
In this type of drainage facility, the entire horizontal axis pump 1 is installed as a single straight water channel, so that the installation area is small, and no ground building is required, and the height of the machine can be kept low. For this reason, civil engineering construction costs can be reduced, and it is said that it is advantageous for large-diameter and multi-unit installation. Further, the straight water flow path from the one end suction port 3 to the other end discharge port 4 is not bent, so that the flow path loss is kept small and high efficiency is obtained, and driving of the electric motor, gear reducer, etc. Since the part is installed inside the pump casing 2, there is an advantage that noise does not go outside.
[0004]
Now, in the drainage system of FIG. 4, when the elbow 7 and the suction bell mouth 8 are omitted and the drainage system of FIG. 5 in which the tip of the suction port 3 is opened to the suction water tank 5 is considered, air suction starts. The minimum water absorption level LWL1 is higher than the upper limit position P2 of the suction port 3 by Δh2, and the horizontal axis pump 1 cannot be operated below this water level. However, as shown in FIG. 4, in the drainage facility in which the elbow 7 bent downward at the tip of the suction port 3 and the suction bell mouth 8 are attached, the upper limit position of the suction port, that is, the opening upper limit position P3 of the suction bell mouth 8 is illustrated. 5 is reduced by an amount equivalent to Δh from the upper limit position P2 of the suction port 3, and the lowest water absorption level LWL2 is reduced by an amount equivalent to Δh3 from the lowest water absorption level LWL1, thereby reducing the amount of residual water below the lowest water absorption level LWL2. be able to. That is, the remaining water amount in the suction water tank 5 in the drainage facility in FIG. 4 can be made smaller than the remaining water amount in the suction water tank 5 in the drainage facility in FIG.
[0005]
[Non-Patent Document 1]
“Mechanical Map Pump” by the Japan Society of Mechanical Engineers
Meijin Printing Co., Ltd., February 20, 1980, p. 64 FIG.
[0006]
[Problems to be solved by the invention]
However, in the drainage facility in which the elbow 7 and the suction bell mouth 8 that are bent downward are attached to the tip of the suction port 3 in FIG. 4, the suction water tank 5 is further provided corresponding to the depth H from the lower limit position of the suction port 3. It has to be deeply dug down, and there is a problem that the cost of civil engineering construction increases accordingly. In the drainage facility of FIG. 4, the water cross-sectional area is rapidly reduced at the entrance of the bell mouth 8, so that the water flow is disturbed and air suction vortices are easily generated. For this reason, depending on the shape of the suction water tank 5 or the relative relationship between the suction water tank 5 and the suction bell mouth 8, an air suction vortex may occur at a level slightly higher than the lowest water absorption level LWL2. Therefore, the actual minimum water absorption level must be set higher than the minimum water absorption level LWL2, and the remaining water amount in the suction water tank 5 increases accordingly.
[0007]
The present invention has been made in consideration of such circumstances, and although the excavation depth of the suction water channel corresponding to the suction water tank is kept shallow, the construction work cost can be reduced, but the air An object of the present invention is to provide a drainage facility using a horizontal shaft pump that can lower the minimum water absorption level at which suction starts and reduce the amount of residual water in the suction channel.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a drainage facility using a horizontal axis pump according to the first aspect of the present invention is a drainage system using a horizontal axis pump including a cylindrical pump casing having both ends opened. One end suction port of the horizontal axis pump faces the suction water channel, and a downward projecting portion having a lower limit position set lower than an upper limit position of the one end suction port is provided on the ceiling of the suction water channel. In the position immediately upstream of the suction port, the ceiling surface of the suction channel is inclined upward from the lower limit position of the downward projecting portion to the upper limit position of the suction port, and the width dimension of the suction channel is gradually narrowed, thereby breaking the channel. The area is gradually reduced from the upstream side to the one end suction port at a position immediately upstream of the suction port.
[0009]
Moreover, it is preferable that the bottom surface level of the suction channel is set to be flush with or substantially flush with the lower limit position of the suction port.
[0010]
According to the first aspect of the present invention, not only the excavation depth of the suction channel can be kept shallow, but also the minimum water absorption level at which the suction of the air of the horizontal axis pump starts is the upper limit of the one end suction port of the horizontal axis pump. It can be set to a level lower than the position, and the water passage cross-sectional area of the suction water channel is reduced smoothly to the suction port without abrupt reduction, allowing water to flow smoothly without being disturbed be able to. As a result, air suction vortices are less likely to occur, and the lowest water absorption level can be set to a lower level.
[0011]
According to the second aspect of the present invention, since the level of the bottom surface of the suction channel is set to be substantially or flush with the lower limit position of the suction port, the level difference is eliminated. Foreign matter such as will not accumulate.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. FIG. 1 is a longitudinal side view showing an embodiment of the present invention, FIG. 2 is a plan sectional view of FIG. 1, and FIG. 3 is an enlarged sectional view taken along line AA of FIG. The same parts as those in FIGS. 4 and 5 are denoted by the same reference numerals.
1 and 2, a horizontal pump 1 is a cylindrical pump (tubular pump), and a drive unit such as an electric motor or gear reducer (not shown) has a horizontal axis (horizontal axis) C. It is installed in the casing 2. There is also a horizontal shaft pump 1 having a structure in which only the electric motor is installed without the reduction gear. The outer shape of the pump casing 2 has a single straight cylindrical shape on the horizontal line C from the one end suction port 3 to the other end discharge port 4.
[0013]
One end suction port 3 of the horizontal axis pump 1 faces a suction channel 9 having a closed cross-sectional structure (closed shape), and the other end discharge port 4 faces a discharge channel 9A. The suction water channel 9 is made of, for example, a concrete structure, and has a closed cross-section structure that is watertightly surrounded by a bottom surface 10, vertical surfaces 11, 11 and a ceiling 12 on both sides in the width direction, as shown in FIG. It extends substantially horizontally from the upstream area of the axial pump 1 to the suction port 3 at one end of the horizontal axis pump 1.
[0014]
On the other hand, on the ceiling 12 of the suction water channel 9, in the vicinity of the one end suction port 3 in the horizontal shaft pump 1, a downward projecting portion in which the lower limit position P1 is set lower than the upper limit position P2 of the suction port 3 by Δh4. (Shaded area in FIG. 1) 13 is provided. The downward projecting portion 13 includes an upstream slope 13A inclined downward from the ceiling 12 to the lower limit position P1, and a downstream slope 13B inclined upward from the lower limit position P1 to the ceiling 12 and the upper limit position P2 of the suction port 3. And is formed of concrete continuously on the ceiling 12 of the suction channel 9 made of a concrete structure. Further, the level of the bottom surface 10 is set to be flush with or substantially flush with the lower limit position of the suction port 3 to eliminate the step.
[0015]
On the other hand, on the vertical surfaces 11, 11 on both sides in the width direction of the suction water channel 9, the width dimension of the suction water channel 9 is measured from the upstream side to the one end suction port 3 at a position immediately upstream of the one end suction port 3 in the horizontal shaft pump 1. Slopes (shaded areas in FIG. 2) 14 and 14 for gradually narrowing and gradually reducing the channel cross-sectional area of the suction channel 9 are provided. That is, the suction side water passage cross-sectional area in the suction water passage 9 is smoothly reduced to the suction port 3 of the horizontal shaft pump 1 without being rapidly reduced, so that the water can flow smoothly without being disturbed. . The slopes 14 and 14 are made of concrete continuously with the elevations 11 and 11 of the suction channel 9 made of a concrete structure.
[0016]
With such a configuration, it is not necessary to dig deeper into the suction water channel 9 than the lower limit position of the suction port 3, so that the excavation depth of the suction water channel 9 can be kept shallow, and civil engineering construction costs can be reduced. . Further, by reducing the minimum water absorption level LWL3 at which the suction of the air of the horizontal axis pump 1 starts by an amount equivalent to Δh5 from the upper limit position P2 of the suction port 3, the amount of residual water below the minimum water absorption level LWL3 can be reduced. . Furthermore, since the level of the bottom surface 10 is set to be flush with or substantially flush with the lower limit position of the suction port 3 and the level difference is eliminated, it acts to avoid accumulation of foreign matters such as sludge on the bottom surface 10.
[0017]
In addition, the slopes 14 and 14 are provided, and the water passage sectional area on the suction side in the suction water passage 9 is not rapidly reduced, but is gently reduced to the suction port 3 of the horizontal shaft pump 1 without disturbing water. Since it is made to flow smoothly, the air suction vortex is hardly generated, and the lowest water absorption level LWL3 can be set to a lower level. That is, the slopes 14 and 14 that gradually reduce the channel cross-sectional area of the suction channel 9 contribute to setting the lowest water absorption level LWL3 to a lower level.
[0018]
In the above-described embodiment, the suction water channel 9 having a closed cross-sectional structure (closed shape) is described. However, the suction water channel 9 may have an open cross-sectional structure (open shape). In addition, although a description has been given of a structure in which two horizontal axis pumps 1 are installed in parallel, the number of horizontal axis pumps 1 to be installed is not limited to two, but one or three. The structure which installed the above in parallel may be sufficient. Furthermore, although the downward projecting portion 13 is described as a structure formed of concrete continuous with the ceiling 12 of the suction channel 9, a structure in which the projecting portion 13 of the steel plate welded structure or the cast structure is integrally provided on the concrete ceiling 12 is described. It may be. Moreover, although the slopes 14 and 14 which protrude so that the width dimension of the suction channel 9 may be reduced are demonstrated with the structure formed with the concrete which continues to the standing surfaces 11 and 11 of the suction channel 9, the concrete vertical surface 11 is demonstrated. , 11 may be provided with slopes 14 and 14 of a steel plate welded structure.
[0019]
【The invention's effect】
As described above, since the drainage facility using the horizontal axis pump according to the present invention is configured, the following special effects are produced.
[0020]
According to the first aspect of the present invention, it is possible not only to reduce the excavation depth of the suction channel and reduce the civil engineering construction cost, but also to set the minimum water absorption level at which the suction of the air of the horizontal axis pump starts at the horizontal axis. By setting the pump lower than the upper limit position of the one end suction port of the pump, it is possible to reduce the amount of residual water below the lowest water absorption level, and the suction channel cross-sectional area of the suction water channel is abruptly reduced. Since the water is smoothly reduced without being disturbed, the air suction vortex is less likely to occur and the minimum water absorption level is set to a lower level. The effect to obtain is acquired.
[0021]
According to the second aspect of the present invention, since the level of the bottom surface of the suction channel is set to be substantially or flush with the lower limit position of the suction port, the level difference is eliminated. Foreign matter such as will not accumulate.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view showing an embodiment of the present invention.
FIG. 2 is a plan sectional view of FIG.
FIG. 3 is an enlarged cross-sectional view taken along line AA in FIG.
FIG. 4 is a longitudinal sectional view of a conventional example.
FIG. 5 is a longitudinal sectional view showing a comparative example with a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Horizontal axis pump 2 Cylindrical pump casing 3 One end suction port of horizontal axis pump 9 Suction channel 12 Suction channel ceiling 13 Downward projecting part 14 Slope which gradually reduces the channel cross-sectional area of the suction channel P1 Lower limit of downward projecting part Position P2 Upper limit position of one end suction port of horizontal axis pump

Claims (2)

A drainage facility using a horizontal shaft pump having a cylindrical pump casing having both ends opened, wherein one end suction port of the horizontal shaft pump faces the suction water channel, and a lower limit position is located on the ceiling of the suction water channel. Is formed at a position lower than the upper limit position of the one end suction port, and a downwardly extending portion is provided at a position immediately upstream of the suction port, and the ceiling surface of the suction channel from the lower limit position of the downward protruding portion to the suction port. A horizontal axis pump characterized in that the cross-sectional area of the water channel is gradually reduced from the upstream side to the one end suction port by inclining upward toward the upper limit position and gradually narrowing the width dimension of the suction water channel. Drainage equipment used.   The drainage equipment using a horizontal axis pump according to claim 1, wherein a bottom surface level of the suction water channel is set to be flush with or substantially flush with a lower limit position of the suction port.

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