JPH06101684A - Vertical shaft pump device - Google Patents

Abstract

PURPOSE:To enable stable running in low water level while reducing pressure variation generated in supplying air into a casing to stabilize the supply of air. CONSTITUTION:A suction bell 2 movable axially of a suction casing 1 is provided outside the suction casing 1 and made of structure and material lighter than water as a whole. A bell mouth 2 is provided on the inner periphery with a plurality of axial vertical grooves 5 and projections guided by the vertical grooves 5 are provided on the outer periphery of the suction casing 1 so that the bell mouth 2 is moved through the projection only by the buoyancy of water. Air is stably supplied into the suction casing 1 through a clearlance 9 between the suction casing 1 and suction bell 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical shaft pump device, and more particularly to a vertical shaft pump device for performing stable operation according to a change in water level at a drainage station.

[0002]

2. Description of the Related Art A conventional vertical shaft pump is, for example, the actual open shaft 6
As discussed in Japanese Patent Publication No. 3-150097, in order to prevent sudden start and stop of pumping, an air supply unit is provided in the suction casing between the impeller and the suction port below the impeller. A ventilation pipe for supplying air from the outside is provided in the supply part, and air is supplied to the inside of the casing using the ventilation pipe by utilizing the pressure difference between the inside and outside of the casing. However, there is a problem that the inflow of air into the casing is unstable, and therefore a variable load is applied to the impeller.

Further, for the purpose of reducing the vibration and noise and operating the pump stably, no matter how the water level of the pump submerged changes, for example, Japanese Utility Model Laid-Open No. 63-1217.
As described in Japanese Patent Publication No. 92, a movable bell mouth is known to be movable up and down with respect to the position of the impeller. Further, Japanese Utility Model Laid-Open No. Sho 63-174593 discloses a pump casing in which an outer cylinder having an open lower end is slidably mounted on the pump casing in order to prevent entrainment vortices at a low water level. The depth of submersion in the suction part was deepened by these.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Inside the thin vent tube as described in Japanese Patent No. 150097, air exists in water in the form of bubbles. Since the gas and the liquid alternately pass through the inside of the ventilation pipe, the density changes greatly and has a strong pulsation characteristic. In particular, when bubbles are united with each other, they are strongly attracted to each other due to the surface tension, so that a large pressure fluctuation occurs and the inflow amount of air into the casing suddenly changes. Therefore, the effect of continuously changing the amount of pumped water is reduced.

FIG. 12 is an operation characteristic diagram of a general pump. That is, FIG. 12 is a so-called Q-H curve in which the horizontal axis represents the flow rate Q and the vertical axis represents the head H. As shown in FIG. 12, the pump changes its operating performance depending on the inflow amount of air, and the impeller Since the load applied to the pump changes, the impeller may vibrate and the pump may not operate if the air inflow changes.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object of the present invention is to reduce the pressure fluctuation generated when air is supplied into the casing and to supply the air. An object of the present invention is to provide a stable vertical shaft pump device.
Another object (second object) of the present invention is to stably supply air to the suction casing to prevent abrupt start and stop of pumping water during operation of the vertical pump, and to stabilize at low water level. An object of the present invention is to provide a vertical axis pump device that enables stable operation.

[0007]

In order to achieve the above object, the most basic constitution of the first invention relating to the vertical shaft pump device of the present invention is such that the portion of the suction casing surrounding the impeller that is to be submerged is a cylinder. In a vertical shaft pump forming a body, a bell mouth is provided outside the suction casing so as to be movable in the axial direction with respect to the suction casing, and a gap for ventilation is provided between the suction casing and the bell mouth. Is provided.

In order to achieve the above object, the structure of the second invention relating to the vertical shaft pump device of the present invention is a vertical shaft pump in which the portion of the suction casing surrounding the impeller to be submerged is a cylindrical body. A bell mouth is concentrically provided on the outer side of the casing with a gap for ventilation with the suction casing, and the bell mouth is vertically movable by buoyancy. More specifically, the bell mouth has a plurality of vertical grooves in the inner circumference thereof, and a protrusion guided by the vertical grooves is provided on the outer circumference of the suction casing. Further, the present invention is provided with a movement preventing means for limiting the movement of the bell mouth, and is characterized in that the lower end of the suction casing is formed in a corrugated shape.

Further, in order to achieve the above object, the structure of the third invention relating to the vertical axis pump device of the present invention is the outside of the suction casing and from the upper part of the bell mouth to the outside of the bell mouth, or the bell mouth. From the top of the mouse to the bottom,
A protrusion is provided to prevent the entry of dust and the like.

Further, in order to achieve the above-mentioned object (particularly the second invention), the structure of the fourth invention relating to the vertical shaft pump device of the present invention is such that the suction is performed in association with the lowering of the bell mouth which rises and falls according to the water level. A means for narrowing the suction portion of the casing inward is provided.

Further, in order to achieve the above object, the structure of the fifth invention relating to the vertical shaft pump device of the present invention is a vertical shaft pump in which the portion of the suction casing surrounding the impeller to be submerged is a cylindrical body. On the outside of the casing, a bell mouth is concentrically provided while keeping a gap for ventilation with the suction casing, and a rack and a bell mouth are provided on the outer periphery of the suction casing, and the bell mouth is configured to be movable in the axial direction. It was done. Then, the bell mouth is provided with a sensor for detecting the water surface, and the pinion drive motor is operated by the output signal of this sensor.

[0012]

The function of the technical means of each of the above inventions is as follows. According to the first aspect of the invention, the suction casing and the bell mouth have a double cylindrical structure, and the bell mouth can freely move in the axial direction outside the suction casing. At this time, there is a gap between the bell mouth and the suction casing, and air can freely pass therethrough.

According to the second aspect of the invention, in addition to the above, the bell mouth is selected such that the material moves up and down in accordance with the change of the water level by the action of buoyancy. Both of the first and second inventions have the following functions. When the water level is lower than in normal drainage operation, the internal pressure of the suction casing is lower than atmospheric pressure, and air passes through the gap between the suction casing and the bellmouth, and the suction casing is drawn from the lower end of the suction casing. Supplied inside Thing. Since the pressure fluctuations generated during air supply are dispersed in the circumferential direction of the casing, the pressure fluctuations transmitted to the suction casing are small, and the air is stably supplied.

Further, the bell mouth moves up and down in conjunction with the water level, and even if the water level becomes low, the distance from the water surface to the lower end of the bell mouth is kept constant for a long time, so that a suction vortex from the water surface does not easily occur. There is. Furthermore, since the distance from the bottom of the water absorption tank is automatically controlled, when the water level is low, the distance between the bottom of the water absorption tank and the bell mouth is narrow, the suction flow rate of the pump is reduced, and the suction vortex is prevented from being entrained from the water surface. To do.

Further, when the water level goes down, a movement preventing means is provided so that the bell mouth does not go down, and the position from the bottom of the water absorption tank is fixed. Further, when the water level rises and normal drainage operation is performed, the bell mouth is provided with a movement preventing means so as to be fixed at the upper limit position. Further, by processing the lower end of the suction casing into a corrugated shape, it is possible to reduce supply from a specific location in the circumferential direction and unstable pressure fluctuations associated therewith.

According to the third aspect of the present invention, a cylindrical projection is provided outside the suction casing and from the upper part of the bell mouth to the outer part of the bell mouth, or from the upper end to the lower part of the bell mouth to prevent dust from entering. By providing, even if the water surface rises above the upper end of the bell mouth, there is an air layer that is sealed between the bell mouth, the protrusion, and the water surface, so that water enters between the bell mouth and the suction casing. There is no need to worry about dust clogging.

Next, the function of the fourth invention will be described.
When the water level further decreases and the amount of drainage decreases, a backflow occurs near the inner wall of the casing, so that even if air is supplied from the inner wall of the casing, the effect of controlling the flow rate becomes weak. Therefore, in conjunction with the lowering of the bell mouth that moves up and down according to the water level, a means for narrowing the lower end of the suction portion of the suction casing acts, and the lower end falls inside the suction casing and the tip of the fallen lower end is Supply air into the casing. As a result, effective flow rate control is possible even in the low flow rate region.

According to the fifth aspect of the invention, the bell mouth moves up and down by mechanical means. That is, the motor rotates the pinion according to the output signal of the sensor that detects the water surface,
Raise and lower the bell mouth by engaging the racks.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Each embodiment of the present invention will be described below with reference to FIGS. First, embodiments of the first and second inventions will be described together with reference to FIGS. 1 to 6. [Embodiment 1] FIG. 1 is a vertical sectional view of a vertical axis pump device according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is a lower end portion of a suction casing. FIG. 4 is an enlarged cross-sectional view, FIG. 4 is a plan view showing a half circumference of the bottom surface of FIG. 3, FIG. 5 is a vertical cross-sectional view showing when the water level rises in the apparatus of FIG. 1, and FIG.
FIG. 6 is a vertical cross-sectional view showing the time when the water level is lowered in the apparatus of FIG. In the drawings, the same parts are designated by the same reference numerals.

The vertical pump P shown in FIG. 1 is installed in a water absorption tank or the like of a drainage pumping station, and the portion of the suction casing 1 surrounding the impeller I that should be submerged in water is a cylindrical body.
A bell mouth 2 which is axially movable with respect to the suction casing 1 is concentrically provided outside the suction casing 1. That is, the suction casing 1 and the bell mouth 2 have a double cylindrical structure. A gap 9 is provided between the suction casing 1 and the bell mouth 2.

A plurality of stoppers 3 for preventing downward movement of the bell mouth 2 are provided on the outer circumference of the suction casing 1, and an annular stopper 4 for preventing upward movement is provided for the suction casing. It is provided on the outer circumference of 1. On the other hand, as many vertical grooves 5 as the number of stoppers-3 are provided on the inner circumference of the bell mouth 2. The stopper-3 vertically moves the bell mouth 2 as a protrusion guided by the vertical groove 5 (see FIG. 2). In FIG. 1, reference numeral 8 denotes the water surface of the water absorption tank, and a space 7 exists between the bell mouth 2 and the water absorption tank bottom surface 6.

Here, the bell mouth 2 has a structure and material lighter than water as a whole, and the buoyancy of water causes the bell mouth 2 to have an upper end 2.
a is located above the water surface 8 and moves up and down according to the change in water level. The bell mouth 2 may have a hollow structure or a porous material, for example.

The state shown in FIG. 1 shows a case where the water level is lower than in the normal drainage operation, and if the bell mouth 2 is not present, the entrainment vortex from the water surface 8 is generated. Assuming that the atmospheric pressure is Pa, the suction casing lower end 1a at a depth h from the water surface.
The pressure Ph at is expressed by the following equation.

[Equation 1] Where ρ is the density of water g is the acceleration of gravity Vh is the flow velocity in the suction casing at the depth h from the water surface ΔPh is the amount of correction such as pressure recovery due to the influence of the lower end of the suction casing

From the equation (1), when the water level is low and the second term on the right side is smaller than the third term (in parentheses), the suction casing internal pressure Ph becomes lower than the atmospheric pressure Pa. At this time, air bubbles 10 are supplied from the lower end 1a of the suction casing to the inside of the suction casing through the gap between the suction casing and the bell mouth. Therefore, the amount of water sucked by the suction casing 1 is reduced, the flow velocity of suction at the bellmouth lower end 2b is reduced, and the generation of suction vortices is prevented.

In the conventional method of supplying air using a ventilation pipe, since air and water having different densities move irregularly throughout the narrow cross section of the pipe, a large pressure fluctuation occurs in the length direction of the pipe. However, air is not supplied stably. However, in the apparatus of this embodiment, since the air is supplied from the lower end 1a of the suction casing, the pressure fluctuation is dispersed in the circumferential direction, the pressure fluctuation transmitted to the suction casing is small, and the air is stably supplied. It As described above, according to the present invention, the air is supplied more stably than the conventional air supply method using the ventilation pipe, so that the effect of preventing the generation of the suction vortex is high.

Further, as shown in FIGS. 3 and 4, by processing the lower end of the suction casing 1 into the corrugated shape 11, air is easily supplied from the valley portion of the corrugated shape, and the air is supplied from a specific portion in the circumferential direction. Unstable pressure fluctuations associated therewith can be reduced.

Since the bell mouth 2 moves up and down by the buoyancy, the distance from the water surface 8 to the bell mouth lower end 2b is kept long even when the water level is lower than in the normal drainage operation, and the water from the water surface 8 is kept. Suction vortex is less likely to occur. Further, since the distance 7 from the bottom surface 6 of the water absorption tank is automatically controlled, when the water level is low, the distance 7 between the bottom surface 6 of the water absorption tank and the lower end 2b of the bell mouth is narrow, and the suction flow rate of the pump becomes small, so that the suction from the water surface is reduced. It is possible to prevent the inclusion of vortices.

FIG. 5 shows a state in which the water level rises and normal drainage operation is performed. At this time, the bell mouth 2 moves upward due to buoyancy and is pressed against the annular stopper-4, and the gap 9 is closed by the stopper-4. That is,
When the water level rises and the upper end 2a of the bell mouth hits the stopper-4, the air supply is stopped. Therefore, it is desirable to set the position of the stopper-4 to a position where the suction vortex from the water surface 8 does not occur. Further, at this position, the lower end 2b of the bell mouth 2 is smoothly connected to the lower end 1a of the suction casing 1.

On the contrary, when the water level is lowered and the water surface 8 becomes lower than the lower end 1a of the suction casing, the water cannot be drained originally, but the bell mouth 2 is lowered so that the water can be drained. At this time, the gap 7 between the water absorption tank 6 and the bellmouth lower end 2b is the narrowest and the suction flow rate is the smallest, so that it has an effect of suppressing the entrainment of vortices generated from the water surface. Further, as shown in (Equation 1), the pressure Ph at the lower end 1a of the suction casing is
Becomes lower than the atmospheric pressure Pa (h <0), and air is supplied into the suction casing 1 through the gap 9, so that the generation of suction vortex can be prevented.

When the water level further decreases, the amount of bubbles 10 increases and the water runs out. The operating state of the vertical pump device when the water level drops is shown in FIG. Considering the position where water is drained beforehand, a plurality of stoppers-3 are provided on the outer circumference of the suction casing 1.
Is provided, and the bell mouth 2 lowered according to the water level is held as shown in FIG. However, when the water level 8 decreases and the amount of drainage decreases, a backflow occurs near the inner wall of the suction casing 1, so that even if air is supplied from the inner wall of the casing, the effect of flow rate control becomes weak. Note that measures against this will be described later in [Example 3].

[Embodiment 2] Next, an embodiment of the third invention applied to the drainage operation when the water level rises in FIG. 5 will be described with reference to FIG. FIG. 7 is a vertical sectional view of a vertical shaft pump device according to another embodiment of the present invention. In the figure, those having the same reference numerals as those in FIG. 1 are the same parts as those in the previous embodiment, and therefore their explanations are omitted. The vertical pump apparatus shown in FIG. 7 is the apparatus of FIG. 1 provided with a protrusion 12 for preventing the intrusion of dust and the like.

During the drainage operation when the water level rises, the water level rises from the upper end of the bell mouth 2, and dust (dust) in the water may enter between the bell mouth 2 and the stopper 4 and clog the gap 9. There is. Therefore, as shown in FIG. 6, a cylindrical protrusion 12 is provided outside the suction casing 1 and
It was provided from the upper part of the bell mouth 2 to the outside of the bell mouth 2 or from the upper end to the lower part of the bell mouth 2. here,
The space between the bell mouth 2 and the cylindrical protrusion 12 is sufficiently wide so that clogging of dust or the like does not occur. Surface 8
Even when the bell mouth 2 rises above the upper end 2a of the bell mouth 2, since there is a closed air layer 13 between the bell mouth 2, the projection 12 and the water surface 8 ', water is absorbed between the bell mouth 2 and the suction casing. It does not get in between 1 and there is no concern about clogging with dust.

[Embodiment 3] Next, an embodiment of the fourth invention applied to drainage operation when the water level is lowered is shown in FIGS.
This will be described with reference to 0. FIG. 8 is a longitudinal sectional view of a main part showing a structure of a lower end portion of a suction casing according to still another embodiment of the present invention with a half of the structure being abbreviated with respect to the center, and FIG. FIG. 10 is a vertical cross-sectional view of a main part of the lower end portion of the suction casing of FIG. 8 in operation, in which half is omitted from the center. In the figure, those having the same reference numerals as those in FIG. 1 are the same parts as those in the previous embodiment, and therefore their explanations are omitted.

The suction casing 1A shown in FIG. 8 is provided with means for narrowing the suction portion of the suction casing 1A inwardly in association with the lowering of the bell mouth 2A which moves up and down according to the water level. That is, the lower end portion 14, which is the lower end portion of the suction portion of the suction casing 1A, is separated into a plurality of parts that can be laid up and down with respect to the suction casing body via the spring material 15, and the plurality of lower end portions 14 are concerned. The bell mouth 2A is provided with a guide 16 which is a guide member for supporting the rising and lowering of the lower end portion 14, and a plurality of vertical grooves 17 for guiding the plurality of guides 16 in a predetermined range.

As the water level lowers, the bell mouth 2A lowers, and the upper end 17a of the vertical groove 17 comes into contact with the guide 16 and pushes down the guide 16 when a backflow occurs. Therefore, as shown in FIG. 10, the lower end portion 14 interlocked with the spring member 15 is bent inside the suction casing 1A, and the tip end 1 of the lower end portion 14 is broken.
4a moves toward the center of the suction casing 1A. At this time, since the bubble 10 is discharged from the tip 14a, the bubble 10 is supplied while avoiding the influence of the backflow.

According to the present embodiment, as described above with reference to the example shown in FIG. 6, when the water level decreases and the amount of drainage decreases, a backflow occurs near the inner wall of the suction casing, and the casing It is possible to deal with the problem that the effect of flow rate control becomes weak even if air is supplied from the inner wall.

[Embodiment 4] In each of the above embodiments, the bell mouth 2 is moved up and down by buoyancy, but it may be moved up and down by other methods. Next, an example will be described. FIG. 11 is a vertical sectional view of a vertical shaft pump device according to still another embodiment of the present invention. In the figure, those having the same reference numerals as those in FIG. 1 are the same parts as those in the previous embodiment, and therefore their explanations are omitted. In the apparatus shown in FIG. 11, a rack 21 is provided on the outer periphery of the suction casing 1B, a pinion 20 is provided on the bell mouth 2B, and the bell mouth 2B is configured to be movable in the axial direction. That is, the bell mouth 2B is provided with the sensor 18 for detecting the water surface, and the output signal of the sensor 18 operates the drive motor 19 of the pinion 20 to move the bell mouth 2B up and down in the axial direction by the engagement between the pinion 20 and the rack 21. It is something.

According to the present embodiment, it is possible to obtain the same effect as that of the vertical axis pump device using the bell mouth which moves up and down by buoyancy as shown in FIG. However, since a mechanism for moving the bell mouth 2B up and down must be incorporated, the costly disadvantage is unavoidable.

[0039]

As described in detail above, according to the present invention, there is provided a vertical shaft pump device which reduces pressure fluctuations generated when air is supplied into the casing and stabilizes the air supply. be able to. Further, according to the present invention, a vertical pump that stably supplies air to the suction casing, prevents abrupt pumping and stopping of pumping during the operation of the vertical pump, and enables stable operation at a low water level. A device can be provided.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a vertical shaft pump device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is an enlarged sectional view of a lower end portion of a suction casing.

FIG. 4 is a plan view showing a half circumference of the bottom surface of FIG.

5 is a vertical cross-sectional view showing when the water level rises in the apparatus of FIG.

FIG. 6 is a vertical cross-sectional view showing when the water level is lowered in the apparatus of FIG.

FIG. 7 is a vertical sectional view of a vertical shaft pump device according to another embodiment of the present invention.

FIG. 8 is a longitudinal sectional view of an essential part showing a structure of a lower end portion of a suction casing according to still another embodiment of the present invention.

9 is a plan view of the suction casing of FIG. 8 seen from below.

10 is a longitudinal sectional view of a main part of the lower end portion of the suction casing of FIG. 8 at the time of operation.

FIG. 11 is a vertical cross-sectional view of a vertical shaft pump device according to still another embodiment of the present invention.

FIG. 12 is an operating characteristic diagram of a general pump.

[Explanation of Codes] 1,1A, 1B Suction casing 2,2A, 2B Bell mouth 3,4 Stopper-5 Vertical groove 9 Gap 11 Waveform 12 Protrusion 14 Lower end 15 Spring material 16 Guide 17 Vertical groove 18 Sensor 19 Motor 20 Pinion 21 rack

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Otani 603 Jinritsu-cho, Tsuchiura-shi, Ibaraki Pref., Inside the Hitachi Co., Ltd. Tsuchiura factory

Claims (10)

[Claims] 1. A vertical axis pump in which a portion of a suction casing surrounding an impeller to be submerged has a cylindrical body, and a bell mouth is provided outside the suction casing so as to be movable in an axial direction with respect to the suction casing. A vertical axis pump device, wherein a gap for ventilation is provided between the suction casing and the bell mouth. 2. A vertical axis pump in which a portion of a suction casing surrounding an impeller to be submerged is a cylindrical body, and a bell mouth is concentrically provided outside the suction casing with a gap for ventilation to the suction casing. A vertical shaft pump device in which the bell mouth is configured to be movable in the vertical direction by buoyancy. 3. The bell mouth according to claim 1, wherein the bell mouth has a plurality of longitudinal grooves in the axial direction, and the projections guided by the longitudinal grooves are provided on the outer circumference of the suction casing. Vertical shaft pump device of either. 4. The vertical pump apparatus according to claim 1, further comprising a movement preventing means for limiting movement of the bell mouth. 5. The vertical axis pump device according to claim 1, wherein the lower end of the suction casing is formed in a corrugated shape. 6. A protrusion for preventing dust and the like from entering outside the suction casing and from the upper part of the bell mouth to the outer part of the bell mouth or from the upper end to the lower part of the bell mouth. The vertical pump apparatus according to any one of 1 and 2. 7. The vertical shaft pump according to claim 1, further comprising means for narrowing the suction portion of the suction casing inwardly in association with the lowering of the bell mouth which moves up and down according to the water level. apparatus. 8. The means for narrowing the suction portion of the suction casing inwardly is such that the lower end of the suction portion of the suction casing is separated into a plurality of portions that can be raised and lowered with respect to the suction casing body via an elastic member. A plurality of vertical grooves for guiding the plurality of guide members in a predetermined range are provided on the inner circumference of the bell mouth, the guide member supporting the rising and lowering of the lower ends of the suction parts for each of the plurality of suction part lower ends. The vertical axis pump device according to claim 7, wherein. 9. A vertical axis pump in which a portion of a suction casing surrounding an impeller to be submerged is a cylindrical body, and a bell mouth is concentrically provided outside the suction casing with a gap for ventilation to the suction casing. A vertical axis pump device, wherein a rack and a pinion are provided on a bell mouth and an outer periphery of the suction casing, and the bell mouth is configured to be movable in an axial direction. 10. The vertical pump apparatus according to claim 9, wherein the bell mouth is provided with a sensor for detecting the water surface, and the drive motor of the pinion is operated by the output signal of this sensor.