JP2005264839A - Suction cover structure for drain pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suction cover structure for a drain pump, having simple construction for securing stable operation by actualizing the suction of water from a water storage tank having a large bottom area down to its sufficiently low level while suppressing the occurrence of air suction swirl. <P>SOLUTION: The suction cover structure for the drain pump 6 is installed in the water storage tank 3 with an axis P in a horizontal attitude, connected its base end to a suction port 6A of the drain pump 6 which delivers water stored in the water storage tank 3 to the outside, and provided with opening portions 7C in the peripheral wall, from which the water is sucked by the drain pump 6. A suction cover 7 has the opening portions 7C whose areas are each smaller than the minimum cross section area of the suction port 6A and whose gross area is larger than the minimum cross section area. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention has a bottom area such as a pump well constructed in a rainwater pumping station or a sewage pumping station, or a long cylindrical water storage pipe installed in the ground to temporarily store rainwater during heavy rain. The present invention relates to a suction cover structure for a drainage pump for sending water stored in a water storage tank, which has a large amount of residual water unless it is sucked to a large low water level and is difficult to sufficiently drain for subsequent storage.

  As shown in FIG. 7, the vertical pump P installed in the pump well 10 or the like of the drainage pump station has the lowest operable water level LWL unique to the vertical pump P, and the water level of the pump well 10 is the lowest operable water level. If drainage operation is performed in an area below LWL, vortex may be generated and air mixed water will be sucked in, causing severe vibration and loud noise, causing pump operation malfunction, and damaging the foundation and building of the drainage station. is there.

  On the other hand, an expansion bell mouth 12 having a large suction port is attached to the lower side of the suction cover 11 and a structure that reduces the suction flow velocity and suppresses the generation of vortices is adopted, so that the conventional operable minimum water level LWL or less. It is conceivable to reduce the amount of residual water by draining to the above area, but in this case, the enlarged bell mouth 12 having a considerably large suction port must be used, so that the vertical shaft pump P becomes large and has a large installation space. -There was a problem of requiring a service.

Therefore, as shown in FIG. 8, by forming a plurality of through holes 12 in the suction cover 11 below the lowest operable water level LWL unique to the vertical pump P, not only the suction ports 13 of the suction cover but also the plurality of through holes 12 are formed. In addition, a configuration has been proposed in which drainage operation is possible in a region below the conventional minimum operable water level by reducing the suction flow velocity from the suction port and suppressing the generation of vortices by sucking water.
Japanese Utility Model Publication No. 6-12787

  However, according to the above-described conventional technology, it is possible to suction to a low water level while suppressing the generation of air suction vortex, but the suction cover shaft center is arranged in a vertical posture in the pump well. Yes, in the case of a very large tank such as a long cylindrical water storage pipe installed in the ground, there is a large amount of residual water even if it is sucked to some low water level, and sufficient drainage for subsequent storage is not possible. There was a problem.

  Even if the conventional suction cover described above is arranged so that its axial center is in a horizontal position, for example, if the water level is lowered to some extent, air is simultaneously sucked from the bell mouth part, causing intense vibration and large noise, and pump operation It was not possible to solve the problem of causing a malfunction in the function. In that case, it is possible to lower the water level that can be sucked in the bell mouth portion with the upper opening portion of the bell mouth portion bent toward the bottom, but in the case where a large bell mouth is provided, the size of the pump is increased. There was also a possibility that the solid foreign matter at the bottom was sucked in at the same time as water and the pump was abnormal.

  In view of the above-mentioned conventional drawbacks, the present invention enables stable operation with a simple structure while suppressing the generation of air suction vortices and allowing suction to a sufficiently low water level even in a water storage tank having a large bottom area. It is in the point which provides the suction cover structure of the drainage pump which can ensure.

  In order to achieve the above-mentioned object, the first characteristic configuration of the suction cover structure of the drainage pump according to the present invention is as described in claim 1 of the claims. The base end is connected to the suction port of a drainage pump that is installed along the bottom of the tank and feeds water stored in the reservoir to the outside, and an opening through which water is sucked by the drainage pump A drainage pump suction cover structure formed on a peripheral wall, wherein the suction cover is formed with an opening having a smaller area than a minimum sectional area of the suction port of the drainage pump, and the total of the openings The area is larger than the minimum cross-sectional area.

  By making the total area of the opening of the suction cover larger than the minimum cross-sectional area of the suction port of the pump, the flow velocity at the opening becomes smaller than the flow velocity such as the air suction vortex, and vibration and noise are generated in the impeller. It is possible to avoid the generation of the air suction vortex. Therefore, the suction cover is installed in the water storage tank with its axis centered in a substantially horizontal posture or along the bottom of the tank, and the opening for water absorption formed in the suction cover is smaller than the minimum sectional area of the suction port of the drainage pump. By forming the openings as small-area openings in a distributed manner and forming the total area of the openings to be larger than the minimum cross-sectional area, thereby suppressing the occurrence of air suction vortices in the openings. Thus, it is possible to efficiently drain water to a low water level while preventing the occurrence of vibration and noise that can lead to failure.

  In this case, the generation of air suction vortices at the opening is suppressed, and the shaft center is substantially horizontal or the suction cover is installed in the water storage tank along the tank bottom, so that the water can be sufficiently discharged to a low water level. . In other words, the minimum operable water level can be set very low.

  In addition, since the small-diameter openings are dispersedly formed, the flow velocity distribution flows in from a plurality of openings of the suction cover in a relatively uniform state, and the flow velocity is smoothly maintained toward the suction port of the drain pump. Therefore, the load fluctuation of the drainage pump is suppressed and stable operation is ensured. Moreover, since the entry of solid foreign substances having a large particle diameter is avoided from the small-diameter opening, it is possible to prevent the entry of solid foreign substances such as dust larger than the allowable foreign substance passage diameter of the pump, which may damage the drainage pump. In addition, even if some of the openings are blocked by such foreign matter, water is stably absorbed from many other openings, so that no inconvenience occurs.

  In the second characteristic configuration, as described in claim 2 of the same column, the axial center of the water storage tank is installed along a substantially horizontal posture or along the tank bottom surface, and the water stored in the water storage tank is supplied to the outside. The drain pump suction cover structure has a base end connected to the suction port of the drain pump and an opening through which the water is sucked by the drain pump is formed in the peripheral wall, and the slit is formed in the suction cover. And the total area of the openings is larger than the minimum cross-sectional area of the suction port of the drainage pump.

  Even with such a configuration, by making the total area of the opening formed in the suction cover larger than the minimum cross-sectional area of the suction port of the pump, the flow velocity at the opening is made smaller than the flow velocity of the air suction vortex and the like. It is possible to avoid the generation of air suction vortices that generate vibration and noise in the impeller. That is, the suction cover is installed in the water storage tank with its axis centered in a substantially horizontal posture or along the tank bottom, and an opening for water absorption formed in the suction cover is formed as a slit-shaped opening, and By forming the opening so that the total area is larger than the minimum cross-sectional area, it is possible to suppress the generation of air suction vortices at the opening and to prevent the occurrence of vibration and noise that can lead to failure. Therefore, it becomes possible to drain to a low water level.

  In the third feature configuration, as described in claim 3 of the same column, in addition to the first or second feature configuration described above, the opening is formed below a horizontal plane including the axis of the suction cover. It is in the point.

  With such a structure, the minimum water level that can be operated can be set lower while more reliably suppressing the occurrence of air suction vortices due to the suction of air from the free water surface of the water storage tank to the suction cover. Even in a tank, the amount of residual water can be extremely reduced.

  In the fourth characteristic configuration, as described in claim 4 of the same column, in addition to any of the first to third characteristic configurations described above, the tip of the opening is positioned below the opening. The nozzle is provided.

  With such a configuration, even when the installation depth of the suction cover depending on the installation position of the drainage pump is shallow, it becomes possible to avoid the intake of air from the free water surface of the water tank and to suck in water to a lower water level. .

  The characteristic configuration of the water supply method from the water storage tank according to the present invention includes the drainage pump suction cover structure described in any one of the first to fourth characteristic configurations described above. The suction cover is installed in the water storage tank, and its base end is connected to the suction port of the drainage pump to supply water from the water storage tank to the outside.

  According to the above-described method, even a water storage tank having a large bottom area can be suctioned to a sufficiently low water level by the drainage pump device while suppressing the generation of air suction vortices and the like.

  As described above, according to the present invention, even in a water storage tank with a large bottom area, while suppressing the generation of air suction vortices, it is possible to suction to a sufficiently low water level, and furthermore, stable operation with a simple structure. It is now possible to provide a suction cover structure for a drainage pump that can secure the above.

  Embodiments of a suction cover structure for a drainage pump according to the present invention will be described below. As shown in FIG. 2, when the amount of water in the pipeline 1 increases when it rains, the sewage and rainwater are stored in the same pipeline 1 and transported to a wastewater treatment plant. The overflow water from the weir 1a provided in the channel 1 is branched by the branch pipe 2 and drained to the water storage tank 3 buried in the ground, thereby avoiding disasters such as floods and floods. Has been. The water tank 3 is a large water tank with a pipe diameter of several meters and a pipe length of several kilometers, which can temporarily store a large amount of water. However, when the weather is fine, the water tank 3 can be used as a wastewater treatment plant. A pump facility 4 is provided to send water toward.

  The pump facility 4 is installed in, for example, a manhole 5 provided in the vicinity of the water tank 3, a tubular pump 6 as a drainage pump attached to a mounting base 5 </ b> A provided at the bottom of the manhole 5, and the water tank 3 And a drainage pipe 8 for supplying water sucked into the tubular pump 6 to the sewer pipe 1.

  The suction cover 7 will be described in detail. As shown in FIG. 1, the axial center P is installed in a horizontal posture in the water storage tank 3, and the suction of the tubular pump 6 that supplies the water stored in the water storage tank 3 to the outside. A base end portion 7A is connected to a mouth (600 mm diameter) 6A, and an opening portion 7C through which water is sucked by the tubular pump 6 is formed below the peripheral wall, specifically, a horizontal plane including the axis P of the suction cover 7. Has been.

  That is, the opening 7C is formed in the peripheral wall portion of the suction cover 7 such that small-diameter openings are distributed along the direction of the axis P, and the area S1 of each opening 7C corresponds to the suction port 6A. It is formed to be smaller than the minimum cross-sectional area Smin (the area of the cross section along the line aa in the figure) and the total area of each opening 7C is larger than the minimum cross-sectional area Smin. By reducing the flow velocity at the section and suppressing the generation of vortex flow, it is possible to efficiently drain water to a low water level while preventing the generation of vibration and noise that may lead to pump failure.

  With the above-described configuration, when a pump having a diameter of 600 mm similar to that described above is used using a suction cover provided with a conventional bell mouth portion, the minimum water level LWL at which the pump can be operated due to the generation of a vortex or the like is 1.5-1. For example, even if the suction cover 7 having a diameter of about 1000 mm and a length of about 7000 mm is used, the minimum water level LWL that can be operated by the pump is about 0.5 m, so that water can be absorbed to a very low level. is there.

  The diameter of the suction port of the pump 6 and the diameter and length of the suction cover 7 described above are merely examples, and the diameter of the suction port of the pump 6 to which the present invention is applied and the diameter and length of the suction cover 7 are limited thereby. Is not to be done. Further, the number and diameter of the openings formed in the suction cover 7 and the arrangement and interval of the openings are not particularly limited. As described above, the area S1 of one opening 7C is the above-described area S1. There is no particular limitation as long as it is formed so as to be smaller than the minimum cross-sectional area Smin of the suction port 6A and the total area of each opening 7C is larger than the minimum cross-sectional area Smin.

  In the above-described embodiment, the opening 7C has been described as being formed on the peripheral wall, specifically, below the horizontal plane including the axis P of the suction cover 7, but the present invention is not limited to this. As shown in FIG. 3, the opening 7C may be provided with a nozzle N whose tip is located below the opening. In this case, the minimum operable water level LWL is further lowered. Is also possible.

  Further, the openings 7 </ b> C may be uniformly distributed along the circumferential direction and the axial center direction of the suction cover 7 or in the circumferential direction.

  Further, the diameter of the opening 7C is formed to be at least smaller than the allowable foreign substance passage diameter in order to prevent solid foreign substances in the water storage tank 3 from entering solid foreign substances such as dust larger than the allowable foreign substance passage diameter of the pump 6. It is preferred that

  The shape of the opening 7C may be appropriately set such as a circle, an ellipse, or a rectangle, and may be a slit shape as shown in FIG. In this case, the length of the slit may be substantially the same as or shorter than the length of the suction cover. Furthermore, the width and shape of the slit can be appropriately changed within the scope of the present invention.

  In the above-described embodiment, the hollow cover shape is adopted as the shape of the suction cover 7. However, the shape of the suction cover 7 is not limited to this, and may be a rectangular tube shape or an elliptical tube shape. As shown in FIG. 5, an uneven portion may be provided along the bottom shape of the water storage tank 3. In this case, a position corresponding to the concave portion of the bottom surface of the water storage tank 3 in the side surface of the suction cover 7 is formed in the convex portion, and the opening 7C is formed in the convex portion, so that it is possible to absorb water to a lower water level. Moreover, the cross-sectional area of the suction cover does not need to be constant. For example, the cross-sectional area on the downstream side may be increased so that the inside of the suction cover has a constant flow velocity.

  In the above-described embodiment, the tubular pump is used as the drainage pump. However, as shown in FIG. 6A, for example, the type of the pump is not particularly limited, such as using a vertical pump. The number of pumps is not limited to one, and a plurality of pumps may be installed. Moreover, as shown in FIG.6 (b), a column type submersible pump may be used. Further, in the above-described embodiment, the suction cover 7 has been described as being used when water is sucked up from a large-capacity water storage tank embedded in the ground, but the use of the suction cover 7 is limited to this. Needless to say, the present invention can be applied to a pump well where a drainage station is installed.

The suction cover structure of the drainage pump of this invention is shown, Aa line is explanatory drawing which shows the position of the minimum cross-sectional area (Smin) of the suction inlet of a drainage pump Explanatory drawing of the pump equipment using the suction cover structure of the drainage pump of the present invention Explanatory drawing of the suction cover which shows another embodiment Fig. 4 shows another embodiment, (a) is an explanatory view of a suction cover in which a slit-like opening is formed along the axis, (b) is a sectional view taken along the line AA of (a), and (c) is an axis Explanatory drawing of the suction cover in which the wide slit-shaped opening part was formed along the heart, (d) is BB sectional drawing of (c), (e) is CC sectional drawing of (c). , (F) is a sectional view taken along line DD of (c). Explanatory drawing of the suction cover which shows another embodiment FIG. 4 shows another embodiment, (a) is an explanatory view of a drainage pump facility in which a plurality of drainage pumps are connected to the suction cover, and (b) is a drainage pump facility in which a plurality of column-type submersible pumps are connected to the suction cover. Illustration of Explanatory drawing of suction cover structure of conventional drainage pump Explanatory drawing of suction cover structure of conventional drainage pump

Explanation of symbols

1: (sewage) pipe 2: branch pipe 3: water tank 4: pump equipment 5: manhole 6: (tubular) pump 7: suction cover 7A: suction cover base end 7B: suction cover tip 7C: opening P: axis

Claims (5)

The axial center of the water storage tank is installed along a substantially horizontal posture or along the tank bottom surface, and its base end is connected to a suction port of a water discharge pump that supplies water stored in the water storage tank to the outside. The suction cover structure of the drainage pump in which the opening through which water is sucked is formed in the peripheral wall,
An opening of a drainage pump in which openings having a smaller area than the minimum cross-sectional area of the suction port of the drainage pump are dispersedly formed in the suction cover, and a total area of the opening is formed larger than the minimum cross-sectional area. Suction cover structure. The axial center of the water storage tank is installed along a substantially horizontal posture or along the tank bottom surface, and its base end is connected to a suction port of a water discharge pump that supplies water stored in the water storage tank to the outside. The suction cover structure of the drainage pump in which the opening through which water is sucked is formed in the peripheral wall,
A drainage pump suction cover structure in which a slit-like opening is formed in the suction cover, and a total area of the opening is larger than a minimum sectional area of the suction port of the drainage pump.   The suction cover structure of the drainage pump according to claim 1 or 2, wherein the opening is formed below a horizontal plane including an axis of the suction cover.   The suction cover structure for a drainage pump according to any one of claims 1 to 3, wherein a nozzle whose tip is positioned below the opening is provided in the opening.   A suction cover having a drain pump suction cover structure according to any one of claims 1 to 4 is installed in a water storage tank, and its base end is connected to a suction port of the drain pump to draw water from the water storage tank. A method of water supply from a water tank that supplies water to the outside.

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