JP4775786B2 - Pump - Google Patents

Description

  The present invention relates to a pumping pump provided in a water storage pit in order to suppress excessive water collection into sewage during rain.

  The pump station is provided at a predetermined sewage collection point in order to prevent sewage overflow in heavy rain. In other words, a vertical pump for drainage is installed in a water storage pit equipped with an inlet and an outlet for sewage, and when the water storage level of the water storage pit exceeds a predetermined height, the pump is operated to a river or the like. I try to drain.

  In such a pump station, an operation method called a prior standby operation has been conventionally employed. This is because if there is rainfall and a large amount of rainwater is expected to flow into the sewer, the pump must be started (empty operation) before the inflow begins, and a delay will occur in response to the sudden inflow of rainwater, sewage, etc. Without draining. Even if the water storage level drops once due to the operation of the pump, the pump is similarly idled to prepare for the next inflow.

  FIG. 4 is a diagram showing an example of a pump for performing this type of operation. An L-shaped pumping pipe casing (casing body) 22, a liner casing 24, A pump casing 16 in which the suction pipe 26 is integrated is provided. The lower end of the suction pipe 26 is a suction port 26a that opens in a trumpet shape. An impeller 20 driven by a vertical rotating shaft 18 is installed in the pump casing 16, and the impeller 20 is driven to rotate by a motor (not shown) so that liquid is sucked from the suction side of the pump casing 16 and discharged from the discharge side. It is supposed to exhale. A drain pipe 28 connected to a river or the like is connected to the downstream side of the water pump casing 22.

In this pump, an intake port 36 penetrating to a position LLWL lower than the lowest water level LWL by h≈v ² / 2g is provided at a position below the impeller 20 of the suction pipe 26. Here, the minimum water level LWL is a water level that starts to suck air spirally from the water surface outside the pump casing when the water level is lowered by the operation of the pump when there is no intake port 36 and intake pipe 38. This value is specific to the pump, which is determined by the structure of the pipe diameter and the drainage capacity. Moreover, v is the flow velocity of the water at the time of rated operation, and g is the gravitational acceleration. An intake pipe 38 is attached to the intake port 36, and the intake pipe 38 is open upward to the atmosphere. In the figure, HWL is the highest water level of the water storage pit 10, and SLWL is the water level at the lower end of the impeller.

  In this pump, when the standby operation is performed in a state where the water surface is lower than that of the impeller 20, the impeller 20 rotates in the air, and an empty operation in which no pumping is performed is performed. When rainwater or sewage flows into the water storage pit 10 and the water level rises to SLWL, an air-water mixing operation is performed in which air is drawn from the opening of the intake pipe 38 and water is also pumped. Further, when the water level rises to the lowest water level LWL, the suction of air from the intake pipe 38 is stopped by the head due to the water level, and normal drainage operation is performed.

  On the other hand, when drainage progresses and the water level in the water storage pit 10 decreases to the lowest water level LWL, air is automatically sucked from the opening of the intake pipe 38 and the air-water mixing operation starts. Therefore, a situation in which the pump sucks air from the outside of the casing and the casing vibrates is prevented. When the water level drops to LLWL, the intake pipe enters a vented state, the water in the pump casing 16 falls and breaks the vacuum, and the space around the impeller is filled with air and returns to the idle operation. By repeating the drainage operation and the idling operation accompanying such a water level change, the preceding standby operation is continuously performed.

Japanese Patent Laid-Open No. 2002-266786

However, in the conventional technique as shown in FIG. 4, when the water level becomes lower than the minimum water level LWL and the air-water mixing operation is performed, a swirling flow is generated also below the impeller due to the rotation of the impeller, and the intake port As a result of shifting the inner end portion to the positive pressure side, even if the water level falls below the lowest water level LWL, sufficient intake is not performed.
Therefore, it is conceivable to provide a rib plate that prevents the swirling flow below the impeller. However, it is difficult to obtain a sufficient swirl flow prevention effect only by providing a small rib plate along the inner wall.

  The present invention has been made in view of the above points, and provides a pump that prevents a swirling flow at an intake port and can continuously perform a smooth advance standby operation by intake air from the intake port. With the goal.

The pump according to claim 1 is a pump casing that is suspended in a water storage pit and has a suction port opened downward, an impeller that rotates integrally with a shaft that extends in the longitudinal direction in the pump casing, Pumped water provided with a slit-shaped intake port provided in the upstream side of the lower end of the impeller of the pump casing and extending in the circumferential direction, and an intake pipe having one end communicating with the intake port and the other opened to the atmosphere In the pump, the shaft body extends upstream from the lower end of the impeller, and a bearing box that supports the vicinity of the lower end of the shaft body is provided, and the bearing box connects the bearing box and the pump casing. A plurality of support plates are provided on the downstream side of the intake port, and the air flowing in from the intake port is dispersed by the bearing box support plate .

  Thereby, since the shaft body can be supported at two locations on the upstream side and the downstream side of the impeller, the load on each bearing can be reduced. This is particularly effective for non-water-filled bearings. Further, the shaft body can be supported in the vicinity of the lower end thereof, and the shaft body is lubricated even in the non-water supply operation, so that the preceding standby operation is smoothly performed.

According to a second aspect of the present invention, there is provided a collective pump device in which a plurality of pumps according to the first aspect are arranged in the same water storage pit, and the height of one or more pump impellers among the plurality of pumps is high. They are arranged so that their positions in the vertical direction are different.

According to the first aspect of the invention, the shaft body can be supported at two locations on the upstream side and the downstream side of the impeller, so that the load on each bearing can be reduced. Is valid. Further, the shaft body can be supported in the vicinity of the lower end thereof, and the shaft body is lubricated even in the non-water supply operation, so that the preceding standby operation is smoothly performed.
According to invention of Claim 2 , a time difference arises in the pumping operation of each pump, and the water level fluctuation | variation in a water storage pit is suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a pump according to an embodiment of the present invention. This pump is attached to a base 14 installed on a floor plate 12 that covers a water storage pit 10, and has a pump casing 16 that hangs down in the water storage pit 10, and a vertical rotating shaft 18 that is disposed inside the pump casing 16. An impeller 20 and a motor (not shown) connected to the rotary shaft 18 via a speed reducer and rotationally driving the impeller 20 are provided.

  The pump casing 16 includes an L-shaped pumping pipe casing (casing body) 22, a liner casing 24, and a suction pipe 26 that are arranged in the vertical direction from above and are connected to each other via a flange. The lower end of the suction pipe 26 is a suction port 26a that opens in a trumpet shape. A drain pipe 28 connected to a river or the like is connected to the downstream side of the water pump casing 22. A guide vane 25 is provided in the pump casing 16 above the impeller, and functions to convert fluid velocity energy into pressure.

As in the prior art shown in FIG. 4, the suction pipe 26 is located at a position below the tip of the impeller 20 and penetrates at a position LLWL lower than the lowest water level LWL by h≈v ² / 2g. An inlet 36 is provided, and an intake pipe 38 is connected to the intake port 36. In this example, the air inlet 36 is formed in a slit shape extending in the circumferential direction on the inner surface of the air chamber 39, but a plurality of holes communicating with the air chamber 39 may be arranged evenly in the circumferential direction. The water levels HWL, LWL, SLWL, and LLWL are the same as in the conventional case shown in FIG.

  The intake pipe 38 extends in the horizontal direction from the air chamber 39 and is bent upward. In this embodiment, the upper end of the intake pipe 38 is opened above the floor plate 12, but may be opened below this.

  The rotary shaft 18 is supported by a first radial bearing 30 in the middle stage of the pump-pipe casing 22 and a second radial bearing 32 supported by an inner cylinder 27 inside the guide vane 25 as in the conventional case. Further, the rotary shaft 18 passes through the boss portion of the impeller 20 and extends downward to slightly above the intake port 36, and is supported by the third radial bearing 40 at the lower end portion thereof. The third radial bearing 40 is mounted in a bearing box 42 supported by a bearing box support plate described later. The bearing box 42 has a box shape with an opening through which the rotary shaft 18 is inserted.

  At a position between the lower end of the impeller 20 and the intake port, a bearing box support plate 44 that is a plurality of plate-like members protruding radially inward from the inner wall of the pump casing (suction pipe) is provided. As shown in FIG. 2, four bearing box support plates 44 are connected to the bearing box 42 in this embodiment, but an appropriate number of two or more can be arranged. In this embodiment, the bearing box support plate 44 is formed in a flat plate shape arranged along the vertical plane, but is inclined in the opposite direction so as to prevent the swirl flow formed by the impeller 20. In some cases, the swirl flow formed by the impeller 20 may be controlled so as to be in the same direction and gently inclined.

Hereinafter, operation control of the pump according to this embodiment will be described.
The water level in the water storage pit 10 at the start of operation is, for example, below the lower end of the suction pipe 26, and the pump is stopped. If it is predicted that the water level in the water storage pit 10 will rise due to rainfall, the pump will enter a preliminary standby operation and enter an idle operation state that rotates in the air.

When the water level rises and reaches the level SLWL at the lower end of the impeller 20, an air-water mixing operation state in which water is sucked in from the intake pipe 38 is entered. Here, since the bearing housing support plate 44 is disposed on the upstream side of the impeller 20 and prevents the swirling flow from occurring in this portion, a positive pressure due to the swirling flow is generated in the intake port 36 portion. Is prevented, and stable intake from the intake port 36 is ensured. Further, air flows in from the slit-like air inlet 36 extending in the circumferential direction and is subjected to a dispersing action by the bearing box support plate 44, so that the air mixing ratio is uniform throughout the flow path and the load on the impeller 20 is increased. The unbalance is small and the generation of large vibrations is suppressed.
When the water level further rises and reaches the lowest water level LWL, the pressure at the inner end portion of the intake port 36 is also increased by the head due to the water level, air is not sucked, and a normal operating state is obtained.

  Next, when the amount of water entering the water storage pit 10 becomes lower than the amount of pumped water and the water level is lowered, the reverse process is followed. That is, when the water level reaches the lowest water level LWL, the inner portion of the intake port 36 becomes negative pressure, air from the intake pipe 38 flows in, and the air-water mixing operation state is entered. Also here, the bearing box support plate 44 is disposed on the upstream side of the impeller 20 and prevents the swirling flow from occurring in this portion, so that a positive pressure due to the swirling flow is generated in the intake port 36 portion. Is prevented, and stable intake from the intake port 36 is ensured.

  When the water level further decreases and reaches the water level LLWL of the intake port 36, the intake pipe 38 is opened, the space in the pump casing 16 is broken in vacuum, and the water in the pump casing 16 falls and is in an idle operation (standby operation) state. become. Furthermore, if the water level rises, the operation is repeated by repeating the above steps. If the water level drops and the standby operation is stopped, the pump is also stopped.

  Thus, in this pump, since the bearing box support plate 44 is provided so as to cross the flow path in the pump casing 16, the swirling flow is suppressed over the entire width of the flow path. Therefore, the generation of positive pressure due to the swirling flow at the intake port 36 is prevented, and stable intake from the intake port 36 is ensured. As a result, the advance pump operation can be continuously performed in a stable state where there is no vibration or noise.

  In this embodiment, the rotary shaft 18 is supported at the lower end portion thereof by a third radial bearing 40 attached in a bearing box 42 supported by a bearing box support plate 44.

  FIG. 3 shows another embodiment of the present invention, which is a collective pump device in which a plurality (three in this example) of the above-described pumps are installed in the water storage pit 10. Normally, a plurality of pumps are arranged in the water storage pit 10 of the pump station, so that a necessary number of pumps are operated according to the amount of incoming water or used as a reserve.

  The three pumps P1, P2, and P3 have different lengths of the pump-pipe casings 22a, 22b, and 22c. Therefore, the positions of the impellers 20 are different in the state of being installed in the water storage pit 10, respectively. Yes. Except for this point, the pumps P1, P2, and P3 have basically the same structure, and the water levels of LWL, SLWL, and LLWL of the pumps are different from each other.

  In this collective pump device, the pumping of each pump is started and stopped with a time difference. For example, at the time of water increase, the pump at the lowest position starts pumping first, and other pumps start pumping in sequence, so that the water level in the storage pit 10 fluctuates by performing pumping that is larger than the amount of incoming water. Can be prevented, and the burden on the power supply equipment can be reduced.

  In addition, in this embodiment, although the position of the height direction was changed by changing the length of the pumping pipe casings 22a, 22b, and 22c, the height direction can be changed by changing the mounting position of the pump having the same structure. The position may be changed.

It is sectional drawing which shows the structure of the pumping pump of 1st Embodiment of this invention. It is the top view which looked at the pumping pump of FIG. 1 from the bottom. It is sectional drawing which shows the structure of embodiment which applied the pumping pump of this invention to the collective pump apparatus. It is sectional drawing which shows the structure of the conventional pump.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Water storage pit 16 Pump casing 18 Rotating shaft 20 Impeller 26 Suction pipe 26a Suction port 36 Intake port 38 Intake pipe 40 3rd radial bearing 42 Bearing box 44 Bearing box support plate

Claims (2)

A pump casing that hangs down in the water storage pit and opens the suction port downward;
An impeller that rotates integrally with a longitudinally extending shaft in the pump casing;
A slit-like air inlet extending in the circumferential direction provided upstream from the lower end of the impeller of the pump casing;
In a pumping pump provided with an intake pipe having one end communicating with the intake port and the other opened to the atmosphere,
The shaft body extends upstream from the lower end of the impeller, and a bearing box that supports the vicinity of the lower end of the shaft body is provided, and a bearing box support plate that connects the bearing box and the pump casing is provided. A pump according to claim 1, wherein a plurality of pumps are provided on the downstream side of the intake port, and the air flowing in from the intake port is dispersed by a bearing box support plate. A plurality of pumps according to claim 1 are arranged in the same storage pit, and one or two or more pump impellers among the plurality of pumps are arranged in different positions in the height direction. Collective pump device characterized by

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