JPS6390697A - Vertical shaft pump - Google Patents

Abstract

PURPOSE:To reduce variation by providing a vacuum breaking hole section in a lowermost water level position of a pump and an impeller above said position to dispose an intake bellmouth immersed in water necessarily and sufficiently for this position. CONSTITUTION:An impeller 1 is disposed above a specified pump position corresponding to the lowermost water level LWL where air is taken in when the pump is immersed in water and the water level becomes lower than LSL. The normal running is carried out when the water level is higher than LWL. An intake port 3a of an intake bellmouth 3 is disposed to be immersed in water necessarily and sufficiently for the level LWL. When the water level is lowered, a vacuum breaking hole section 8 is exposed on the water surface to suck air so that the pump is run in air to prevent vibration and noise.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a spindle used in a pump intake well or rainwater pump equipment of a drainage pumping station installed mainly for draining waterways during floods, etc. Regarding pumps.

(Prior art) Usually, this type of spindle pump has a minimum water level at which it creates a vortex and sucks air when the water level of the pump suction well in which it is installed falls below the level of the pump. The lowest water level is unique to each shaft pump, and is located, for example, at a position 1.4 to 1.7 times the diameter from the suction port. When the water level falls below this minimum water level, problems such as vibration and noise occur due to air intake, so it is necessary to stop the operation of the pump.

However, due to an increase in the amount of rainwater runoff due to the increase in paving ratio due to the progress of urbanization in recent years, and a decrease in water retention function due to a decrease in green areas, rainwater flowing into pumping stations tends to flow in large quantities and rapidly. On the other hand, because it is difficult to secure sufficient storage capacity of facilities such as pump water intake wells, it is difficult to plan accurate timing for pump operation, and there is an increasing demand for advance standby operation based on rainfall information. ing. However, in order to carry out advance standby operation in a facility where the water level of the pump intake well is subject to significant fluctuations as described above, it is necessary to continue operation even when the water level is below the minimum water level. Therefore, in response to fluctuations in water level, the rotation speed of the pump is controlled so that the rotation speed of the pump is lowered when the water level drops below the minimum water level, and by reducing the pump capacity during operation when the water level is below the minimum water level, vibration is reduced. and noise reduction.

(Problem to be Solved by the Invention) However, the above-mentioned device for controlling the rotation speed controls the rotation speed of the pump in response to fluctuations in the water level of the pump suction well, etc., and the water level of the pump suction well is the lowest level. Since it is a complicated device that prevents the following from occurring, there is a drawback that the control system is considerably complicated and expensive, and there is also a problem in reliability due to the complicated control.

In addition, if measures such as providing the above-mentioned control device are not taken, when the water level in the pump suction well falls below the minimum water level due to water pumping by pump operation, vibrations and the like due to vortex suction will increase. In addition, there are various problems such as an increase in the number of scalps in closed operation or close to closed operation, which causes an increase in vibration and noise.

(Object of the Invention) The present invention has been made in view of such conventional problems.
The purpose of the present invention is to provide a spindle pump which can be operated stably by reducing vibration and noise even when the water level in which the pump is submerged changes, no matter how the water level in which the pump is submerged changes, using an inexpensive configuration using an hour wheel.

(Means for Solving the Problems) In order to achieve the above object, the spindle pump of the present invention has a pump-specific system whose water level when the pump is submerged corresponds to the lowest water level below which air will be sucked in. An impeller is placed slightly above the specific area, and the suction bell mouth is
The suction port at the tip of the pump is placed in a position where it is submerged in water to the necessary and sufficient extent with respect to the specific part of the pump, and a vacuum breaking hole that communicates with the atmosphere is provided at a position equal to or close to the specific part of the pump. It is something.

(Function) This spindle pump is equipped with a vacuum breaking hole at a position equal to or close to a specific part of the pump that corresponds to the lowest water level unique to the pump. When the water level drops below the water level, the vacuum breaking hole is exposed above the water surface, and in order to suck air into the pump from this hole, the water in the suction bell mouth is vacuum broken and falls, and at this time, the impeller is also exposed above the water surface,
It becomes an air driving condition without any problems.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

In FIG. 1, a suction bell mouth 3 is located on the lower side, that is, upstream side, of a casing 2 that is internally installed with an impeller 1 being pivotally supported.
is connected to the pump body, and a lift pipe 4 is connected to the upper side, that is, the downstream side, and a discharge elbow 6 in which a discharge valve 5 is interposed is connected to the upper side of the lift pipe 4, thereby forming a pump body. There is. In addition, the impeller 1 is located above a specific part of the pump corresponding to the lowest water level LWL, which sucks air if the water level falls below this level when the pump is submerged in water, by a distance corresponding to the height of the impeller 1. The suction bell mouth 3 is arranged so that the suction port 3a at the tip thereof can be immersed in water to the necessary and sufficient extent in the specific part of the pump. That is, as is clear from the comparison with the suction bell mouth 31 of the existing similar type of spindle pump shown in FIG.
The suction bell mouth 3 is connected to the casing 2 via the connecting pipe 7.
By being connected to the pipe, it is located at the same height as the suction bell mouth 31 of the existing pump at the same depth. In addition, if the connecting pipe 7 is removed, the suction bell mouth 3 will be replaced accordingly.
may be made longer.

In addition, a vacuum breaking hole 8 communicating with the atmosphere is provided at almost the same position as a specific part of the pump corresponding to the lowest water level LWL, and a backflow relief hole 8 is provided at a position above the impeller 1 in the casing 2. A hole 9 is provided. Figure 2 shows a conventional spindle pump of the same type shown for comparison, with 11, 21, 31, 41 attached to the same figure.
, 51 and 61 are 1.2 in FIG. 1, respectively.
, 3.4, 5. This corresponds to the member labeled Ii.

Next, to explain the action, in the area where the water level at the depth of the submerged trees of the pump placed in the pit P is above the water level WL where the impeller 1 is submerged, the water pumping action by the impeller 1 Normal drainage operation will be carried out.

Then, when the water level decreases due to the drainage operation and reaches the area indicated by B, when the impeller 1 in the area B is sufficiently submerged in water, the drainage operation is performed in the same way as in the area ^, but the lowest water level When the water level drops near the level LWL and the impeller l is exposed above the water surface, the pumping capacity decreases and the water on the downstream side of the pumping pipe 4 flows backward, but this flowing water flows through the backflow relief hole. Vibration and noise caused by collision with the impeller 1 rotating in the forward direction are reduced.

When the water level further decreases to below the lowest water level LWL, the vacuum breaking hole 8 is exposed above the water surface, and air is sucked through this hole 8, causing the water in the suction bell mouth 3 to be vacuum broken. This caused the tank to fall, making it impossible to pump water, and an air operation was carried out. That is, in the water level region C shown in the figure, no vortex suction or breathing phenomenon occurs because the pump is operated in the air and no water is pumped up. Therefore, stable operation with almost no vibration or noise can be performed in any of the regions A, B, and C.

It should be noted that the present invention is not limited only to the above-mentioned embodiments, and it goes without saying that various embodiments are possible without departing from the scope of the claims. For example, the holes 8 and 9 may be and the casing 2 and the casing 2 and the pumping pipe 4, respectively.
A spacer may be interposed between these flanges to form a gap.

In addition, a valve is provided in both or one of the vacuum breaking hole 8 and the backflow relief hole 9 to open and close the hole, so that the valve is closed during normal operation and opened and closed during standby operation. It may also be operated.

Of course, the valve may be an electric valve, and the opening and closing may be controlled automatically according to the water level.

(Effects of the Invention) As detailed above, according to the axle pump of the present invention, the vacuum breaking hole is provided at a position equal to or close to a specific part of the pump's pump corresponding to the lowest water level. An impeller is installed above a specific part,
In addition, the suction bell mouth is placed in a position where it can be submerged in water to the necessary and sufficient extent relative to a specific part of the pump, so when the water level falls below the minimum water level, it automatically switches to submerged operation. No inhalation or breathing phenomena occur, and vibration and noise can be significantly reduced. Moreover, it can be manufactured extremely easily and inexpensively without using expensive equipment such as a rotation speed control device, and can be operated stably at any water level.

In addition, if a backflow relief hole is formed above the impeller,
It is also possible to reduce vibration and noise caused by backflow and avoid shut-off operation.

[Brief explanation of the drawing]

Fig. 1 is a side view of one embodiment of the axle pump of the present invention;
The figure is a side view of a conventional pump. 1... Impeller 3... Suction bell mouth 3a... Suction port 8... Vacuum breaking hole 9... Hole for backflow relief Patent applicant Agent of Kubota Iron Works Co., Ltd.
Patent Attorney Takashi Suzue - Figure 1 Figure 2

Claims (1)

[Claims] (1) An impeller is installed at a position slightly above a specific part of the pump that corresponds to the lowest water level below which air will be sucked in when the pump is submerged, and the suction bell mouth is The suction port at the tip of the pump is placed in a position where it is submerged in water to the necessary and sufficient extent with respect to the specific part of the pump, and a vacuum breaking hole that communicates with the atmosphere is provided at a position equal to or close to the specific part of the pump. A vertical shaft pump featuring: