JP2004239215A - Vertical shaft pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertical shaft pump, making air surely flow into a suction pipe positioned on an upstream side of an impeller, and suitable especially for advanced standby operation. <P>SOLUTION: The vertical shaft pump 10 includes the impeller rotated by a vertical rotary shaft 21 and an air duct having one end connected to an air intake formed on the suction pipe 31 positioned on the upstream side of the impeller 20 and the other end open in a position lower than the highest water level HWL in a water tank 1 and higher than the lowest water level LWL below which air is inhaled from a lower end of the suction pipe, even when the lower end of the suction pipe is positioned lower than a surface of sucked water. The vertical shaft pump is constituted so as to inhale air according to lowering of the pressure in the suction pipe. The air is inhaled into the suction pipe 31 without blocking off the opening end of the air duct with floating materials by making an opening direction of the air duct horizontal or downward from the horizontal or by including a device interrupting the floating materials. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vertical shaft pump, and more particularly to a vertical shaft pump suitable for preceding standby operation.
[0002]
[Prior art]
Conventionally, as shown in FIG. 16, an impeller 2 is provided at the tip of a shaft arranged in the vertical direction, and air is sucked into the impeller 2 together with water, so that the operation can be performed even at the lowest operating water level LWL or lower of the suction water tank 1. There was a vertical pump 3 that made it possible to continue. In this pump 3, the suction pipe 4 on the upstream side of the impeller 2 is moved from the water level LWL to h ≒ v ² A hole 5 for air intake is provided at a position LLWL which is lower by / 2 g, and an air pipe 6 having an opening 6a at the other end above the mounting position of the impeller is attached to the hole 5. Here, v is the flow velocity of the water in that portion, and g is the gravitational acceleration. As a result, below the lowest operating water level LWL lower than the highest water level HWL, the amount of drainage is gradually reduced by the air flowing through the holes 5, thereby avoiding a sudden stoppage of pumping due to the lowering of the water level. Even when the water level rises from the water level below the mounting position of 2, the amount of water discharged through the hole 5 reduces the amount of drainage until the water level reaches the minimum operation water level LWL, thereby avoiding sudden pumping. I have.
[0003]
In this way, for example, for rainwater drainage in a large city, the pump is started in advance based on rainfall information and the like regardless of the suction water level, and when the water level rises from the low water level, the water amount is gradually increased from idle operation while the total amount is increased. When the water level dropped from the high water level, the operation was smoothly transitioned from full operation to idle operation while gradually reducing the water flow. Such a pump is started at a water level LLLWL lower than the lower end of the casing (for example, see Patent Document 1).
[0004]
[Patent Document 1]
Japanese Utility Model Publication No. 5-33752 (page 3-4, Fig. 1)
[0005]
[Problems to be solved by the invention]
However, in the air pipe attached to the conventional pump, there is a problem that the suspended matter in the water is easily sucked, the opening is closed by the suspended matter, and it becomes difficult for air to flow into the suction pipe. In particular, since suspended matter in water often floats on the surface, when the water level is falling, the suspended matter closes the opening before the opening starts to be exposed to the air, and the water level below the minimum operating water level LWL However, there is a problem that it is difficult for air to flow into the suction pipe.
[0006]
Therefore, an object of the present invention is to provide a vertical shaft pump that avoids closing of an air pipe opening due to suction of suspended matter and ensures that air flows into a suction pipe, and is particularly suitable for preceding standby operation.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an upright shaft pump 10 according to the first aspect of the present invention is, for example, as shown in FIG. A suction pipe 31 arranged upstream of the impeller 20 and for flowing water toward the impeller 20; one end connected to the suction pipe 31 and the other end at a position lower than the highest water level HWL of the sucked water, And below that, even when the lower end of the suction pipe 31 is lower than the surface of the water to be sucked, the air pipe 40 is opened at a position higher than the lowest water level LWL at which air is sucked from the lower end of the suction pipe 31. Provided; the opening 41 of the air pipe 40 is horizontal or downward from the horizontal.
[0008]
With this configuration, since the opening of the air pipe is oriented horizontally or downward from the horizontal, it is more difficult to suck in floating substances in the water, which often float on the surface, as compared to the upward opening.
[0009]
As described in claim 2, and for example, as shown in FIG. 1, in the vertical shaft pump according to claim 1, the other end of the air pipe 40 is formed in an inverted U shape, and the opening direction is downward.
[0010]
With this configuration, since the opening of the air pipe is directed downward, it becomes more difficult to suck the suspended matter, and even if the suspended matter is sucked into the opening, it becomes easy to fall with a decrease in the water surface. .
[0011]
In order to achieve the above object, the vertical pump 10 according to the third aspect of the present invention includes, as shown in FIG. 5, for example, an impeller 20 that is rotated by a rotating shaft 21 arranged in a vertical direction and sucks water; A suction pipe 31 arranged upstream of the impeller 20 and for flowing the water toward the impeller 20; one end connected to the suction pipe 31 and the other end at a position lower than the highest water level HWL of the sucked water. And, below that, even when the lower end of the suction pipe 31 is lower than the surface of the water to be sucked in, the air pipe 40 opens at a position higher than the lowest water level LWL at which air is sucked from the lower end of the suction pipe 31. A device 43 for blocking suspended matter at the other end of the air pipe 40.
[0012]
With this configuration, since the device for blocking suspended matter is provided, the device for blocking suspended matter prevents infiltration of the suspended matter in the water into the air pipe, and the suspended matter is not sucked. The opening is also prevented from being blocked by a floating substance.
[0013]
As shown in FIG. 4 and, for example, as shown in FIG. 6, in the vertical pump according to claim 3, the device that shuts off the suspended matter in the air pipe 40 may be the strainer 44.
[0014]
With this configuration, since the strainer is provided, the strainer prevents entry of suspended matter in the water into the air pipe, and the suspended matter is not sucked, so that the opening may be blocked by the suspended matter. Is prevented.
[0015]
Further, as described in claim 5 and, for example, as shown in FIG. 7, in the vertical pump according to claim 3, the device for shutting off the suspended matter in the air pipe may be a breather 45. The breather is a cover having an air gap 46 around the air pipe 40, and blocks water from flowing into the air pipe 40 from the side and the upper part of the breather 45, and the breather lower part 45 a connects the breather 45 to the breather 45. The gap 46 between the air pipes 40 is used as an inflow path of water to the air pipe opening 41.
[0016]
With this configuration, since the breather is provided, when water flows into the air pipe, the water flows in from the lower portion of the breather, so that suction of the floating material floating on the surface is prevented, and Is prevented from being sucked in, so that the opening is also prevented from being blocked by a floating substance.
[0017]
In the vertical pump 10 according to the sixth aspect of the present invention, for example, as shown in FIG. 8, the suction pipe 31 is configured to flow water toward the impeller 20 along the inner wall; The air pipe 40 communicates with the inside of the suction pipe 31 through the suction port 42 so that air is sucked into the suction pipe 31 through the air pipe 40 and the suction port 42 in response to a decrease in pressure in the suction pipe 31. On the inner wall between the impeller 20 and the intake port 42, a turning prevention plate 70 for preventing turning of water due to rotation of the impeller 20 is formed.
[0018]
With this configuration, since the swirl prevention plate is provided, a swirling flow around the axis in the suction pipe can be prevented, and a positive pressure does not occur on the inner wall of the suction pipe due to the swirling flow, and the air pipe flows from the opening. The suction of air into the suction pipe through the suction port is performed according to the water level and the flow velocity in the suction pipe.
[0019]
Further, in the vertical pump 10 according to the invention according to claim 7, for example, as shown in FIG. 10, the suction pipe 31 is configured to flow water toward the impeller 20 along the inner wall. Has an annular air chamber 50 surrounding it; one end of the air pipe 40 is connected to the air chamber 50; an air inlet 51a is formed in the inner wall, and the air chamber 50 communicates with the inside of the suction pipe 31 through the air inlet 51a. In addition, air is sucked into the suction pipe 31 through the air pipe 40 and the suction port 42 in response to a pressure drop in the suction pipe 31; a blade is provided on the inner wall between the impeller 20 and the suction port 51a. A turning prevention plate 70 for preventing turning of water due to rotation of the vehicle 20 is formed.
[0020]
With this configuration, since the swirl prevention plate is provided, a swirling flow around the axis in the suction pipe can be prevented, and a positive pressure does not occur on the inner wall of the suction pipe due to the swirling flow, and the air pipe flows from the opening. The suction of air into the suction pipe through the suction port is performed according to the water level and the flow velocity in the suction pipe, and the annular air chamber is provided, so that the air can be uniformly distributed on the inner wall of the suction pipe.
[0021]
In the vertical shaft pump according to the invention according to claim 8, for example, as shown in FIG. 11, the suction pipe 31 is configured to flow water toward the impeller 20 along the inner wall, and has an annular shape surrounding the inner wall. An air chamber 50 is provided; one end of the air pipe 40 is connected to the air chamber 50; an air inlet 52 is formed in the inner wall, and the air chamber 50 communicates with the inside of the suction pipe 31 through the air inlet 52 to suction air. It is configured to suck air into the suction pipe 31 through the air pipe 40 and the suction port 52 in response to a decrease in the pressure in the pipe 31; air flowing from the air chamber 50 toward the suction pipe 31 is provided in the suction port 52. Are provided.
[0022]
With this configuration, since the annular air chamber 50 and the slit air guide plates 52a to 52d are provided, the flow of air is uniform, and the shape of the guide plate has an effect of inducing air into water.
[0023]
In the vertical pump according to the ninth aspect of the present invention, as shown in FIG. 12, for example, the suction pipe 31 is configured to flow water toward the impeller 20 along the inner wall; The air pipe 40 communicates with the inside of the suction pipe 31 through the suction port 42, and sucks air into the suction pipe 31 through the air pipe 40 and the suction port 42 in response to a decrease in the pressure in the suction pipe 31. The suction pipe 31 has an inner cylinder 81 between the impeller 20 and the intake port 42 which forms an annular inner cylinder space 80 with the inner wall. The upstream side of the inner cylinder 81 is The inner cylinder 81 is connected to the inner wall in the vicinity of the intake port 42, the inner cylinder 81 forms a tapered nozzle having a smaller flow area along the flow of the water, and the inner cylinder space 80 faces the impeller 20 on the downstream side. In the vicinity of the connection between the inner cylinder 81 and the inner wall. Hole 83 which communicates the flow passage 82 of the inner cylinder 81 inside the water 80 is formed.
[0024]
With this configuration, the suction pipe has an inner cylinder that forms an annular inner cylinder space with the inner wall between the impeller and the intake port, and the upstream side of the inner cylinder is near the intake port. Connected to the inner wall, the inner cylinder forms a tapered nozzle that reduces the flow area along the flow of water, and the inner cylinder space is open facing the impeller on the downstream side, so Flows into the inner cylinder space, and a hole communicating the inner cylinder space and the flow path is formed in the vicinity of the connection portion of the inner cylinder with the inner wall, so that the backward flow flows out of the hole. I do. Thus, the swirling flow due to the backflow is suppressed.
[0025]
In the vertical pump according to the tenth aspect of the present invention, as shown in FIG. 13, for example, the suction pipe 31 is configured to flow water toward the impeller 20 along the inner wall, and an annular air surrounding the inner wall. The air pipe 40 has one end connected to the air chamber 50; a slit-shaped intake port 51a is formed in the inner wall, and the air chamber 50 communicates with the inside of the suction pipe 31 through the intake port 51a. Is configured to suck air into the suction pipe 31 through the air pipe 40 and the suction port 51a in response to a decrease in the pressure in the suction pipe 31; the suction pipe 31 is provided between the impeller 20 and the suction port 51a. It has an inner cylinder 81 that forms an annular inner cylinder space 80 between the inner wall and the inner wall. A support plate 84a that connects the inner cylinder 81 and the inner wall is disposed in the inner cylinder space 80. Opened to the flow path 36 near the intake port 51a on the upstream side It is opened to face the impeller 20 on the downstream side. The support plate 84a may function as a water guide plate that supports the inner cylinder 81 and guides the flow of water.
[0026]
With such a configuration, since the inner cylinder forms an annular inner cylinder space with the inner wall, the backflow from the impeller flows through the inner cylinder space. Further, since the support plate for connecting the inner cylinder and the inner wall is disposed in the inner cylinder space, the inner cylinder can be supported by the inner wall. In addition, the support plate can be configured to function as a water guide plate for guiding the flow of water, and in that case, the flow of water can be rectified.
[0027]
In the vertical shaft pump according to the eleventh aspect of the present invention, for example, as shown in FIG. 14, the suction pipe 31 is configured to flow water toward the impeller 20 along the inner wall, and an annular air surrounding the inner wall. The air pipe 40 has one end connected to the air chamber 50; a slit-shaped intake port 51a communicating the annular air chamber 50 with the suction pipe 31 is provided on the inner wall of the suction pipe 31 over the entire circumference thereof. It is formed so as to suck air into the suction pipe 31 through the air pipe 40 and the suction port 51a in response to a decrease in the pressure in the suction pipe 31; a casing is provided between the suction port 51a and the impeller 20. A treatment 85 is formed; the casing treatment 85 includes the inner wall and an outer casing 31e disposed outside the inner wall, and a space 31 between the inner wall and the outer casing 31e. , One is opened to the inlet tip portion of the impeller 20, the other is opened in the vicinity of the intake port 51a, it constitutes a return channel having a length in the axial direction.
[0028]
With this configuration, since the suction pipe has the casing treatment, the backflow from the impeller flows through the casing treatment, and the swirling flow due to the backflow is suppressed.
[0029]
In the vertical shaft pump according to the twelfth aspect of the present invention, as shown in FIG. 15, for example, the suction pipe 31 is configured to flow water toward the impeller 20 along the inner wall; And an inner cylinder 91 forming an annular inner cylinder space 92 between the inner cylinder 91 and the inner cylinder space 92, the downstream side of which is open to face the impeller 20; an air inlet to the suction pipe 31 by the air pipe 40. Reference numeral 42 is open in the inner cylinder 91, and is configured to suck air into the suction pipe 31 through the air pipe 40 and the intake port 42 in accordance with a decrease in pressure of the opening in the inner cylinder 91.
[0030]
Typically, a support member 92a that connects the inner cylinder 91 and the inner wall is disposed in the inner cylinder space 92. The air pipe 40 may pass through the inside of the support member 92a, or may pass through the inner cylinder space 92 separately from the support member 92a.
[0031]
With this configuration, since the backflow from the impeller flows through the inner cylinder space, a positive pressure is hardly generated near the intake port.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the drawings, the same or corresponding members are denoted by the same or similar reference numerals, and redundant description will be omitted.
[0033]
A vertical shaft pump according to a first embodiment of the present invention will be described with reference to the cross-sectional view of FIG. The vertical shaft pump 10 is a pump for preceding standby operation.
[0034]
Preliminary standby operation, especially full speed preparatory standby operation, is to start the pump in advance before rainwater flows into the pump suction tank, start draining as the water level L rises, and maintain the full speed without stopping the pump even if the water level drops. It is to drive in. Even when the drainage is started, the vertical pump 10 does not immediately discharge the essential amount of water. In order to enable operation without discharging the essential water volume, air is sucked in together with water.
[0035]
The structure of the vertical pump 10 will be described with reference to the drawings. The vertical shaft pump 10 includes a pumping pipe casing (casing main body) 33, a liner casing 32, and a suction pipe (suction bell) 31 arranged vertically from above. Each is fastened by a horizontal flange. These constitute a casing in a broad sense.
[0036]
A rotating shaft 21 is provided in the center of the casing in a vertical direction (vertical direction), and an open impeller 20 is attached to a lower end of the rotating shaft 21 (a closed type may be used). The liner casing 32 houses the impeller 20 with a slight clearance from the outer periphery of the impeller 20 (the tip of the open blade). The vertical pump 10 is a mixed flow pump. The mixed flow pump is used when the discharge head is relatively large. A guide vane 35 is provided on the discharge side of the impeller 20 and inside the casing body 33.
An axial pump (not shown) may be used as the pump for the preliminary standby operation. The axial pump is suitable when the flow rate relative to the discharge head is relatively large.
[0037]
The casing main body 33 is configured to include a can body portion in a vertical direction parallel to the rotation shaft 21, a curved tube portion bent horizontally in an upward direction, and a horizontal tube portion connected to the curved tube portion. Is penetrating. A bearing 22c and a seal (not shown) are provided in the through portion. The rotating shaft is supported at three points by a bearing 22a and the bearing 22c provided near the impeller 20, and a bearing 22b provided between the two bearings. A thrust bearing (not shown) supports a vertical load applied to the rotating shaft 21 (that is, the weight of the rotating body including the impeller 20 and the rotating shaft 21 and a fluid force applied to the impeller 20).
[0038]
An installation flange is attached to the casing body 33, and the casing body 33 is installed on the concrete floor 2 as an installation base with the flange. A flange is attached to the horizontal pipe portion of the casing body 33, and the flange is connected to the discharge pipe. The discharge pipe 34 is a pipe for guiding rainwater to a river, the sea, or the like and discharging the rainwater.
[0039]
An intake port 42 is formed in the intake pipe 31 located upstream of the tip of the impeller 20, and an air pipe 40 is connected to the intake port.
[0040]
The other end 41 of the air pipe 40 is opened at a position lower than the highest water level HWL and higher than the lowest water level LWL in the water tank 1 in a horizontal or downward direction below the horizontal. In the present embodiment, the other end of the air pipe 40 is formed in an inverted U shape, and the opening direction is vertically downward. Here, below the minimum water level LWL, even if the lower end of the suction pipe 31 is at a position lower than the level of the water to be sucked, that is, the water level in the water tank 1, air is sucked from the lower end of the suction pipe 31. Water level. In other words, even if the suction pipe 31 goes under the water surface, the water level is, for example, a level at which air is sucked in a vortex shape. The maximum water level HWL is the highest water level that can occur in the water tank 1 or the highest water level in the design of the water tank 1.
[0041]
Although one air pipe 40 may be provided as shown in the figure, a plurality of air pipes, for example, four air pipes are preferable because the air sucked from the air pipe 40 is distributed over the entire circumference of the suction pipe 31. That is, the plurality of intake ports 42 are arranged equally along the circumference of the suction pipe 31.
[0042]
The other end (upper end) 41 of the air pipe 40 is opened between the highest water level HWL and the lowest water level LWL in the water tank 1. Therefore, during operation of the vertical pump 10, the pump is submerged or exposed to the air.
[0043]
The impeller 20 is arranged below the lowest water level LWL. The entire main body portion of the impeller 20, or at least a part thereof, and in particular, a tip portion of the impeller 20 that absorbs water if there is a water level is disposed below the minimum water level LWL.
[0044]
Next, the relationship between the structure in the height direction of the pump 10 and the water level will be described with reference to the partial cross-sectional view of FIG. The water level HWL is the allowable water level of the water tank 1 as described above. The water level L does not rise any more. Below that is the lowest water level LWL. This is a value peculiar to the pump, and is a water level at which the operation of the pump cannot be continued if the water level falls below this level. Typically, below this, the air is sucked in from the lower end of the suction pipe 31 in a swirl shape, and the water level Lc coincides with the water level Lc at which operation cannot be continued due to generation of vibration and noise. This is a value unique to the pump, and if there is no air pipe 40, if the water level falls below the minimum water level LWL, it becomes difficult to continue the operation. In the present embodiment, the air pipe 40 enables operation at a low water level. However, the water level LWL may be determined under conditions other than the suction of the vortex air.
[0045]
The design minimum water level Ld is at least equal to the water level LWL and usually higher than it. The design minimum water level Ld is simply obtained by multiplying the inner diameter of the suction pipe from the lower end of the suction pipe 31 by a predetermined coefficient. The coefficient is, for example, 1.1. The design value has a certain margin, and when the water level is lowered by closing the air pipe 40 with an actual machine, the operation can be performed even if the water level is slightly lower than the design-defined minimum water level Ld.
[0046]
Below the design minimum water level Ld or the minimum water level LWL, there is a suction start water level SLWL of the impeller 20. This water level corresponds to the water level at the tip of the impeller 20. This is because when the water level rises from a low water level and the impeller 20 comes into contact with water, steam-water agitation is started and water is discharged soon.
[0047]
Below the suction start water level SLWL, there is an intake water level A1. This corresponds to the upper end of the intake port 42. When the water level L decreases and reaches the water level LWL, the water level in the air pipe 40 lower than the water level L by the negative pressure component h becomes the water level A1, and the air starts to be sucked into the suction pipe 31 through the air pipe 40. .
[0048]
Below the inlet water level A1, there is a water level A2 at the tip of the suction pipe 31.
[0049]
Further, the operation of the vertical shaft pump 10 will be described with reference to FIG. First, the vertical shaft pump 10 is started in a state where the water level is lower than A2. For example, when rainfall information indicating that heavy rain has fallen in a certain area is entered, it is predicted that the water level in the water tank 1 will suddenly rise after a certain time. In such a case, in a state where the water level L is lower than A2, the vertical shaft pump 10 for the preliminary standby operation is started. This is the start of the preliminary standby operation.
[0050]
The water level L in the water tank rises due to the inflow of rainwater, and exceeds the lower end water level A2 of the suction bell. Even if the water level L exceeds the water level A1, water is not yet sucked up. The impeller 20 is idle.
[0051]
When the water level L further rises and reaches the water level SLWL, the impeller 20 starts stirring with air and water. Then start sucking water. At this time, since air is sucked together with water into the suction pipe 31 from the suction port 42 through the air pipe 40, the pump is not in the operation of discharging the total amount of water as the essential point. That is, the vertical pump 10 is performing the air / water mixing operation. When the water level L further rises, the intake air amount gradually decreases, and instead, the water amount increases. Eventually, when the water level L rises to the water level LWL, the air suction amount becomes zero, and the entire water amount at the essential point is discharged (depending on H on the QH curve (described later) at that time). That is, a steady operation is started.
[0052]
Further, when the water level exceeds the water level of the air pipe opening 41 and rises to the bottom of the pipe at the highest position of the inverted U-shape, the water in the water tank 1 is drawn from the lower part of the suction pipe 31 and is drawn through the air pipe 40. The water also flows into the suction pipe 31 from the port 42. This water level is designated as LO. When the length (falling length) from the top of the inverted U-shape to the opening 41 is small, the difference between the water level LO and the water level of the air pipe opening 41 is small, and the water level LO is small. There is no practical problem even if you consider the water level. The case where the falling length of the inverted U-shape is large will be described later.
[0053]
Further, the water level L rises to a water level between the water level LO and the water level HWL, and the pump 10 continues the steady operation. Thereafter, when the water level L is gradually lowered by the drainage of the pump 10, the suction of the water from the air pipe opening 41 is stopped at the water level LO, and the water does not flow into the suction pipe 31 through the air pipe 40. At the water level LWL (because the water level in the air pipe 40 reaches the inlet water level A1), air starts to be sucked into the suction pipe 31 through the air pipe 40. That is, the gas-water mixing operation is started again. As the water level L decreases, the intake air amount increases, and the water amount decreases instead. When the water level L further decreases and approaches the water level A1, the suction of water ends, and the impeller 20 enters an idle operation state in which the impeller 20 is operated in the air. That is, the pump 10 is in an airlock state in which no water is sucked.
[0054]
The airlock water level is designed to match or be close to the water level A1, which is usually the height of the intake port, but does not always match. There is a case where the water amount becomes zero only when the water level further decreases after passing through A1, or when the water level reaches the lower end water level A2 of the suction bell. In the present embodiment, it is assumed that the airlock water level substantially coincides with the water level A1, and the water amount becomes zero at this water level.
[0055]
In this manner, the impeller 20 continues to idle in the air. When the rainfall continues, the operation is continued as it is, the water level L rises again, and when the water level SLWL is reached as described above, the pump 10 starts sucking water. In this way, regardless of the water level of the water tank 1, the preceding standby operation pump 10 can continue the operation between the idle operation and the operation of the essential point total water amount. The transition between idle operation and essential water operation is smooth because the pump also sucks in air.
[0056]
As described above, even if the water level L falls sufficiently and becomes lower than the water level A2 at the lower end of the suction pipe 31, the pump 10 continues the preceding standby operation. For about 10 minutes after the amount of discharged water becomes zero, water remains in the casing above the impeller 20 (particularly, the discharge casing 33). As a result, water in the casing is drained from a drain hole (not shown). In the subsequent preliminary standby operation, the impeller 20 is idled in the air.
[0057]
As described above, even if the water level L in the water tank rises due to the inflow of rainwater and the water level exceeds A1, water is not yet sucked up, but immediately after the water level falls, the water remains above the impeller 20. When the water level rises again, the water starts to be sucked at the water level A1, which is the height of the intake port.
[0058]
Usually, a plurality of the above-mentioned preceding standby operation pumps are installed at the plant. In such an operation of the plant, if one pump has insufficient drainage due to an increase in water level, the other pumps are started one after another to start operation of a plurality of pumps.
[0059]
Here, the relationship between each water level and the water level Lc at which air is sucked in a spiral form from the lower end of the suction pipe 31 will be described.
[0060]
Generally, when designing a vertical shaft pump, first, an airlock water level is designated by design specifications. That is, the water level decreases from the high water level, and finally the drainage level stops. Normally, the airlock water level is designed to match the water level A1 of the intake port. Check the airlock water level during test run. The actual airlock water level is not higher than the inlet position, but is at a lower position or almost the same height.
[0061]
In general, the design specification also specifies a position at which drainage starts when the water level rises from a low water level, that is, an impeller tip position SLWL.
[0062]
When the water level A1 is determined, the design water level Ld that is the total discharge water amount is calculated by the water level Ld = A1 + h. Here, h = hl + (v ² / 2g). In the simple calculation, h = (v ² / 2g) x 1.1.
[0063]
Here, v is the suction flow rate of water calculated by (the essential point total water amount) / (the suction area of the suction pipe 31). (V ² / 2g) is the negative pressure generated by the water flow calculated from Bernoulli's theorem. It may be called speed head. Hl is a flow loss from the lower end A2 of the suction pipe 31 to the intake port 42. In the above simple calculation, hl = (v ² /2g)×0.1, the flow loss from the lower end A2 of the suction pipe 31 to the intake port 42 is empirically obtained using a coefficient. Of course, the head loss from the lower end A2 of the suction pipe 31 may be calculated or measured strictly.
[0064]
The designed water level Ld that is the total discharge water amount is the water level calculated as described above, and when the water level L is rising, the suction of the air from the intake port 42 disappears and the pump becomes the full discharge, When the water level L is in a downward trend, it is a water level at which the full discharge is completed and the air starts to be sucked in from the intake port 42.
[0065]
The design water level Ld, which is the total discharge water amount, has a margin with respect to the water level Lc at which air is sucked from the lower end of the suction pipe 31 in a vortex shape. Therefore, at this water level, air is not sucked from the lower end of the suction pipe 31. That is, the water level Ld is equal to or higher than the water level LWL, usually the water level Lc.
[0066]
Below that, the water level Lc at which the air is sucked in from the lower end of the suction pipe 31 in a vortex shape and vibration or noise is generated and the operation cannot be continued is a check item in obtaining the water level Ld as described above. That is, when the water level Ld obtained in the design process becomes lower than the water level Lc, the design is modified so that the water level Ld becomes equal to or higher than the water level Lc. For example, the suction pipe 31 is lengthened to lower the water level Lc. The water level Ld is calculated as, for example, 1.1 × the inner diameter of the suction pipe from the water level A2.
Experience has shown that Ld does not become lower than the water level Lc.
[0067]
In the vertical shaft pump 10 of the present embodiment, the impeller 20 is disposed below the water level LWL, and further below the water level Lc.
[0068]
Here, it is assumed that the water level L rises from a position lower than the water level LO to a position higher than the water level LO, and then falls to a position lower than the water level LO.
[0069]
As described above, when the water level L exceeds the water level LO, the water in the water tank 1 starts to be sucked in from the air pipe opening 41. At this time, the suspended matter in the water is also sucked in from the air pipe opening 41. In particular, the suspended matter often floats on the surface, and when the water level L is slightly higher than the water level of the air pipe opening 41, the suspended matter is often sucked. When the water level L is higher than the water level LO, the air pipe opening 41 is blocked by a floating substance, and the inflow of water from the air pipe opening 41 to the water suction pipe 31 through the air pipe 40 and the intake port 42 is blocked. However, there is no problem in the operation of the vertical shaft pump 10. However, even when the water level L falls below the water level LO, the air pipe opening 41 is exposed to the air, and the water level L falls below the minimum operating water level LWL, the air pipe 40 and the intake port 42 are not removed from the air pipe opening 41. If the suction of the air into the suction pipe 31 through the air is blocked by the floating matter, the operation of the vertical shaft pump 10 is hindered as described above, for example, the air is sucked in a spiral form from the lower end of the suction pipe 31. Note that the same result is obtained even when the water level LO matches the minimum operation water level LWL.
[0070]
The position of the air pipe opening 41 must be higher than the water level at which air is sucked into the suction pipe 31 through the air pipe 40 and the intake port 42, that is, the minimum operating water level LWL. The length of the pump becomes longer, and damage is likely to occur during transportation and installation work for installing the vertical pump, so that the protection of the air pipe becomes complicated. In addition, if the air pipe is long, the number of supports for supporting from the casing increases, which is uneconomical in manufacturing. Therefore, the shorter the air tube, the better.
[0071]
Further, at the position of the air pipe opening 41, a water level at which air is sucked into the suction pipe 31 through the air pipe 40 and the intake port 42 can be set. At a higher water level, the air pipe opening 41 is installed at a height at which the essential water amount is discharged without sucking air through the air pipe 40 and the intake port 42. The suction of air through the air pipe 40 and the intake port 42 is not necessarily started when the water level falls below the water level of the air pipe opening 41, but at least the water level L falls to the position of the air pipe opening 41. If the water level L rises up to or beyond the position of the air pipe opening 41, the essential water amount will be discharged.
[0072]
That is, the air pipe opening 41 may be submerged, and may suck not only air but also water in the water tank 1 as described above. Therefore, floating substances floating in the water may be sucked, and the floating substances often float particularly on the water surface.
[0073]
Therefore, for example, as shown in FIG. 1, the air pipe opening 41 is oriented horizontally or downward from the horizontal, in particular, the opening side end is formed in an inverted U-shape, and the opening direction is oriented vertically downward, so that the water surface is The suction of nearby suspended matter can be reduced. When the opening is upward, the water is sucked to collect the surface water when the water level is slightly higher than the water level of the opening, but when the opening is downward, the water is sucked to collect the surface water Never.
[0074]
Further, in order to suck a large floating substance, the floating substance may be locked in the air pipe opening 41 and may block the air pipe opening 41. In this case, when the water level falls and becomes equal to or lower than the water level of the air pipe opening, the air pipe opening 41 is exposed to the air, and the water level is equal to or lower than the water level LO. Absent. Then, the water flow that has locked the suspended matter at the opening of the air pipe disappears. When the air tube opening is downward, there is generally no force to support the floating material in the air tube opening 41, and the floating material falls by gravity. Even when the suspended matter is fitted into the air tube opening 41, if the air tube opening is downward, it is easy to fall.
[0075]
Next, a modification of the first embodiment will be described with reference to the partial diagram of FIG. As shown in FIG. 3A, by setting the opening direction of the air pipe 40 to be horizontal, the air pipe 40 is locked to the air pipe opening 41 more than when the air pipe opening 41 faces upward. The floating matter that may block the air pipe opening 41 is likely to fall when the air pipe opening 41 is exposed to the air.
[0076]
Further, as shown in FIG. 3B, the air pipe opening 41 faces the casing 30, and the distance between the air pipe opening 41 and the outer wall of the casing 30 is adjusted, so that a large distance from the air pipe opening 41 is obtained. Inhalation of suspended matter can be prevented.
[0077]
Alternatively, as shown in FIG. 3 (c), the upper plate extending horizontally from the outer wall of the casing 30 above the air tube opening 41 to the front of the air tube opening 41 and the air from the entire side edge of the upper plate. The air pipe opening 41 may be covered with a roof enclosure 47 by a side plate extending below the pipe opening 41. Even with such a structure, the air tube opening is opposed to the vertical plate, and by adjusting the distance between the air tube opening 41 and the vertical plate, a large floating substance is sucked from the air tube opening 41. Can be prevented. In particular, since the air pipe 40 can be provided near the casing 30 as compared with the case where the air pipe opening 41 faces the casing 30, it is easy to support the air pipe 40 from the casing 30. Installation becomes easier.
[0078]
Further, as shown in FIG. 3D, when the opening side end of the air tube 40 is formed in an inverted U-shape, and the tip end thereof is formed in a bell mouth shape which becomes wider as it goes further forward, the flow of the opening becomes larger. As the road area is increased, the flow rate at which water is sucked is reduced, so that the floating material is not easily sucked, and the opening 41 has a large area, so that the floating material is less likely to be blocked by the floating material.
[0079]
Further, as shown in FIG. 3 (e), if the opening side end of the air pipe 40 is formed in an inverted U-shape, and a device 43 for blocking a floating substance such as a strainer described later is provided at the end thereof. Also, the floating material floating in the inverted U-shaped opening is blocked by the device for blocking the floating material, and the floating material is prevented from being sucked into the air pipe 40. In the case where the device for blocking the suspended matter is a strainer, the mesh surface of the strainer may be in a direction of sucking water from a vertically downward direction or may be sucked in a horizontal direction.
[0080]
Next, a second embodiment will be described with reference to a partial view of FIG. This embodiment is a case where water does not flow through an air tube formed in an inverted U shape. Until now, the embodiment has been described assuming that there is not much difference in height between the uppermost portion of the inverted U-shape and the opening. However, as shown in FIG. If the height up to the portion 41 is made sufficiently long, water will not be sucked through the air pipe 40 and the intake port 42. As shown in FIG. 4B, after the water level L reaches the water level of the opening, when the water level L further rises, the air in the air pipe 40 is trapped. As the water level L rises, the water level in the air pipe also rises. However, since the air inside is compressed and the pressure rises, the rise in the water level in the air pipe is greater than the rise in the water level L as shown in FIG. Is also smaller. Therefore, as shown in FIG. 4 (d), even when the water level reaches the maximum water level HWL, the inverted U-shaped pipe is formed so that the water level on the opening side in the air pipe does not exceed the bottom of the pipe at the highest position of the inverted U shape. If the length on the opening side is determined, the water in the water tank 1 will not be sucked into the suction pipe 31 through the air pipe 40 and the intake port 42. Therefore, no floating matter is sucked into the opening. The shape of the air pipe for preventing water from being sucked is individually determined based on the maximum water level HWL, the opening water level, the negative pressure h at the intake port, and the like.
[0081]
Next, a third embodiment of the present invention will be described with reference to the sectional view of FIG. In the present embodiment, as shown in the figure, a device 43 for blocking suspended matter is provided at the end of the opening of the air pipe 40 so that the air pipe 40 does not suck water in the water tank 1 directly from the opening. Has become. The device for blocking the suspended matter prevents the suspended matter from being sucked into the air pipe 40.
[0082]
Next, a fourth embodiment of the present invention will be described with reference to a partial view of FIG. In the present embodiment, as shown, a strainer 44 is provided at the end of the air tube 40 on the opening side. The strainer is a device that generally has a mesh-like mesh 44a in a flow path of water and captures suspended matter in flowing water passing through the mesh. The mesh 44a need not have a mesh shape, and may have a structure that captures suspended matter larger than the minimum size that hinders the operation of the vertical pump 10 regardless of the shape, such as a slit shape or a perforated plate shape. . The strainer is installed so that the lowest part of the mesh 44a is at the water level LO. This is because the air is sucked in only when the lowermost portion of the mesh 44a is exposed to the air. Further, in the strainer, it is preferable to increase the area of the mesh 44a so that the entire mesh 44a is less likely to be blocked by a floating substance. Further, as shown in FIG. 6, when the mesh 44a has a cylindrical shape, the entire surface of the mesh 44a is less likely to be blocked by the suspended matter. Further, when the mesh 44a is installed vertically as shown in FIG. 6, the suspended matter locked on the mesh 44a while the water in the water tank 1 is sucked through the strainer 44 is also used by the strainer 44. When exposed to air, it is easy to fall due to gravity, so when the water level goes down and the air is sucked into the suction pipe 31 through the strainer 44 and the air pipe 40, the suspended matter of the mesh 44a may obstruct the air inflow. Can be prevented.
[0083]
Next, a fifth embodiment of the present invention will be described with reference to a partial view of FIG. In the present embodiment, as shown, a breather 45 is provided at the end of the air tube 40 on the opening side. Here, the breather is a cap-shaped cover that generally has an inner diameter larger than the outer diameter of the air tube 40 and a closed side surface of the cylinder and the upper surface of the cylinder, and a lower portion 45a between the breather 45 and the air tube 40. This is a device for making the gap 46 of FIG. When a breather is provided, the breather lower part 45a is installed at a water level at which air is sucked into the suction pipe 31 through the air pipe 40. When the water level falls below the breather lower portion 45a, the air flow path to the air pipe opening 41 is secured for the first time, and the air is sucked into the suction pipe 31 through the air pipe 40. The width of the gap between the inner wall of the breather and the air pipe may be made smaller than the size of the minimum suspended matter that hinders the operation of the vertical pump 10 to block the suction of the suspended matter. It may be larger than the minimum suspended matter size that hinders driving.
[0084]
Alternatively, a structure may be adopted in which the side of the breather 45 is extended to the upper portion above the highest water level HWL and the upper portion is opened, as shown in FIG. 7B, without closing the upper portion of the breather. In this structure, the flow path into the suction pipe 31 through the air pipe 40 of the water in the water tank 1 becomes the air pipe opening 41 from the breather lower part 45a and the gap 46. The flow path of the air into the suction pipe 31 through the air pipe 40 is from the upper opening of the breather to the air pipe opening 41 through the inside of the breather and to the air pipe opening 41 from the breather lower part 45a and the gap 46. It becomes a flow path. In particular, even when the water level L is equal to or lower than the air pipe opening water level and equal to or higher than the height of the breather lower portion 45a, the former air flow path is ensured. That is, in such a structure, the water level of the opening of the air pipe is set at the water level LO.
[0085]
As shown in FIG. 7C, a hole 45b for inflow of water may be formed on a side of the breather 45 below the air pipe opening 41. In such a structure, the flow path into the suction pipe 31 through the air pipe 40 of water in the water tank 1 becomes the air pipe opening 41 from the breather lower part 45a, the hole 46b, and the gap 46. When the water level falls below the hole 45b of the breather, a flow path of air to the air pipe opening 41 is secured through the gap 46, and the suction of air into the suction pipe 31 through the air pipe 40 can be started. The upper end of 46b is set at the level of the water level at which air is sucked into the suction pipe 31 through the air pipe 40. With such a structure, the inflow port of water into the breather becomes large, and the flow velocity at the inflow port becomes slow, so that it is difficult to suck the suspended matter.
[0086]
Next, a sixth embodiment of the present invention will be described with reference to the sectional view of FIG. There is no problem when the discharge flow rate of the pump is near the design point, but on the small water flow side from the design point, a backflow from the discharge side to the suction side occurs on the outer peripheral side of the impeller 20. Therefore, in addition to the axial flow, a swirling flow around the axis is generated in the suction pipe 31, and this swirling flow generates a positive pressure near the inner wall of the suction pipe 31.
[0087]
The design water level Ld that is the total discharge water amount is calculated by the water level A1 + h, and h = hl + (v ² / G), but a positive pressure hp is actually generated near the intake port 42. This is due to the swirling flow generated inside the suction pipe 31. That is, it is considered that the positive pressure is generated by the centrifugal force generated by the swirling flow.
[0088]
In consideration of the positive pressure hp, h is as follows.
h = hl + (v ² / 2g) -hp
[0089]
When the positive pressure hp is generated, no air is sucked from the air pipe 40 even if the water level L decreases to the water level Ld. Therefore, the air-water mixing operation is not performed as expected, and air may be sucked from the lower end of the suction pipe 31 in a swirl shape, causing vibration or the like.
[0090]
According to the sixth embodiment of the present invention, on the inner surface of the suction pipe 31 between the impeller 20 and the intake port 42, the flat anti-rotation plate 70 is provided radially and axially (vertically). Formed towards. When the suction pipe 31 is made of a casting, the rotation preventing plate may have an integral structure. A plurality of rotation prevention plates are provided. For example, there are four sheets. When the swirl prevention plate is provided, the swirl prevention plate 70 prevents the swirling flow in the suction pipe 31, so that hp becomes substantially zero or sufficiently small, and air can be sucked when the water level L becomes Ld. Alternatively, air can be sucked in where the water level L is not much lower than Ld.
[0091]
Here, the characteristics of the vertical shaft pump 10 will be described with reference to the QH curve in FIG. This figure is a diagram showing the performance of the full-speed preceding standby operation pump, the total head H (%) on the vertical axis, and the discharge amount Q (%) on the horizontal axis. In addition to the case of the steady operation in which the air is not sucked, the change of the pump performance due to the change of the air inflow is also shown.
[0092]
In the same figure, a curve A represents a flow rate-head (QH) curve, a curve B represents a resistance curve at a planned lift (straight line C), and a curve D represents a resistance curve at a maximum actual head (straight line E). . The state of the curve d is a case where the discharge pressure fluctuates greatly and the discharge pressure is high. A curve indicated by a two-dot chain line obtained by moving the curve A in the direction of the origin is a QH curve of the air-water mixing operation of sucking air. The intersection of each QH curve and the resistance curve is the operating point in each state.
[0093]
In the case of the pre-standby operation pump for rainwater drainage, the drainage height to the river or sea to be drained generally does not change much. However, at least the water level in the water tank 1 changes from A1 to HWL. FIG. 1 or FIG. 8 shows a case where the height difference between A1 and HWL is not so large. However, in practice, the discharge casing 33 can be made longer, for example, it may exceed 10 m. . In such a preceding standby operation pump, even when the essential point A is set between the water level Ld and the HWL, when the water level becomes Ld, the resistance curve becomes a curve d. In other words, in the preceding standby operation pump of the above example, since there is a head difference of 10 m between the planned head and the maximum actual head, an operation state in which the flow rate is small as indicated by the point B necessarily occurs.
[0094]
A point A in FIG. 9 indicates an operating point (the essential point) when there is no air inflow at the planned actual head. At this time, the pumped water in the suction pipe 31 is uniformly distributed to the impeller 20 in the axial direction. It is flowing toward you. A point B in the figure indicates an operating point when there is no air inflow at the maximum actual head, which is an operating point that is considerably smaller than the maximum efficiency point. At this time, a backflow occurs on the outer peripheral side of the impeller 20, and therefore, in the pumping in the suction pipe 31, a swirling component is generated near the inner wall of the suction pipe 31 so as to be twisted in the rotation direction of the impeller 20. .
[0095]
The above-described swirling prevention plate 70 prevents such swirling flow, and thus has an effect of reducing the positive pressure hp. In the above description, the device for preventing the swirling flow is described as a plate-shaped swirling prevention plate. However, the swirling prevention plate may be a protrusion, or provided with circumferential irregularities on the inner wall of the suction pipe 31. Alternatively, an intake port may be provided in the recess.
[0096]
Next, a seventh embodiment of the present invention will be described with reference to the sectional view of FIG. In the present embodiment, since the annular air chamber 50 is provided on the inner wall of the suction pipe, the air sucked into the suction pipe 31 through the air pipe uniformly spreads over the entire circumference of the suction pipe 31.
[0097]
The structure and operation of the air chamber will be described with reference to an enlarged view of the air chamber 50 in FIG. In FIG. 10B, the upper end of the slit 51a is formed to be lower by ha than the opening of the air pipe 40 to the air chamber wall 50a. Therefore, even if the water level L becomes the minimum water level Ld and the water level in the air pipe 40 drops to the opening of the air pipe 40 to the air chamber wall 50a, the air is not yet sucked into the suction pipe 31. The water level L further decreases, the water level in the air pipe 40 further decreases by ha, and when the water reaches the upper end of the slit 51a, the suction of air starts.
[0098]
With such a structure, if the space above the slit 51a of the air chamber 50 is sufficient, even if there is only one air pipe 40, the air uniformly spreads over the entire circumference of the suction pipe 31. . In particular, if ha is set large, such an effect can be expected. If a plurality of air pipes 40 are arranged at equal intervals in the circumferential direction of the annular air chamber 50, the air chamber 50 can be made smaller.
[0099]
Further, as shown in FIG. 10 (c), if the upper end of the slit 51a is not a straight line when viewed from the front, but is formed into a wavy shape, a periodic notch is provided, and a shape having a periodic vertical change is provided. Since air flows into the suction pipe 31 uniformly from the high portion into the suction pipe 31 over the entire circumference, air suction into the impeller 20 can be made uniform.
[0100]
Next, an eighth embodiment of the present invention will be described with reference to a partial sectional view of FIG. FIG. 11A is a partial cross-sectional view showing only the vicinity of the air chamber 50. 11 (b), 11 (c), 11 (d), and 11 (e) are cross-sectional views taken along line XX of the suction pipe at the position of the slit 52.
[0101]
In the present embodiment, a slit 52 as an intake port similar to the slit 51a of the above embodiment is formed in the suction pipe 31 in an annular shape. The slit 52 is formed in a slit shape as a narrow gap along the air chamber, and communicates the air chamber 50 with the inside of the suction pipe 31.
[0102]
Further, the slit 52 is formed with a column 52a that straddles the slit 52 and connects the inner wall of the suction pipe 31 at the upstream side and the downstream side.
[0103]
As shown in FIG. 11B, in the first modified example, the columns 52a are equally arranged in the slit 52. The support columns 52a can be formed so as to leave the casing wall (inner wall) so as to close the slits at equal intervals. The ratio of the wall left as the support 52a and the slit as the communication port may be such that the total opening of the slit is larger than the total of the support 52a. It is preferable that the length of each of the openings in the circumferential direction be 0.1 times or less the inner diameter Da of the suction pipe 31 in the slit forming portion.
[0104]
In addition, as shown in FIG. 11C, the support may constitute an air guide plate 52b that guides the air flowing from the air chamber 50 into the suction pipe 31. With this configuration, since the air flow can be directed in the radial direction, there is an effect that the swirling flow in the suction pipe 31 is reduced.
[0105]
Further, as shown in FIG. 11D, the air guide plate 52c may be inclined in the turning direction of water with respect to the radial direction. With such a configuration, there is an effect of inducing the sucked air to swirl the water, and the air is easily sucked regardless of the swirling flow.
[0106]
Further, as shown in FIG. 11 (e), after the air guide plate 52d is inclined in the turning direction of water with respect to the radial direction, the tip of the air guide plate 52d is attached to the casing (in the present embodiment, the suction pipe 31). You may make it protrude from the inner surface of. With this configuration, in addition to the effect of inducing the sucked air to swirl the water, the swirling flow is weakened. The amount of protrusion is preferably about 0.1 times or less the inner diameter of the suction pipe 31 toward the center of the suction pipe 31 or less.
[0107]
The column or guide plate has the effect of guiding the air and also supporting the weight of the portion of the suction pipe 31 below the slit.
[0108]
In FIG. 11, the eighth embodiment has been described as including the turning prevention plate 70 in addition to the support slit, but the turning prevention plate 70 may be omitted in view of the air-inducing effect of the support slit. . In particular, in the case of the modification described with reference to FIGS. 11D and 11E, the turning prevention plate 70 can be omitted.
[0109]
In the eighth embodiment, the width of the slit 52 in the axial direction is preferably set to be 0.005 to 0.05 times the diameter of the suction pipe 31. The width of the support 52a is 0.005 to 0.05 times the diameter of the suction pipe. The number is preferably 16 or less around the periphery.
[0110]
In the seventh and eighth embodiments of the present invention, the backflow prevention plate 70 has a linear shape in the axial direction, but its radial height is smaller than the inner diameter of the suction pipe 31 at the mounting position of the backflow prevention plate 70. It is preferably 0.1 times or less. Further, it is preferable that the axial length of the backflow prevention plate 70 is not more than 0.3 times the inner diameter of the suction pipe at that position.
[0111]
Next, a ninth embodiment of the present invention will be described with reference to the partial sectional view of FIG. In the present embodiment shown in FIG. 12A, the suction pipe 31 has an inner cylinder 81 that forms an annular inner cylinder space 81a between the suction pipe 31 and the inner wall between the impeller 20 and the intake port. are doing. The inner cylinder 81 has an upstream side, that is, a vertically lower portion, connected to the inner wall in the vicinity of the intake port 42, and the inner cylinder 81 forms a tapered nozzle whose flow passage area decreases along the flow of water. The inner cylinder space 81a is open downstream facing the impeller 20. A hole 83 is formed near the connection of the inner cylinder 81 with the inner wall of the suction pipe 31 to communicate the inner cylinder space 81a with the water flow path 82 inside the inner cylinder.
[0112]
With this configuration, the flow flowing backward on the outer peripheral side of the impeller 20 in the small flow rate region flows between the inner cylinder 81 forming the nozzle and the inner wall of the suction pipe 31, and passes through the hole 83 to form the suction pipe 31. The swirling flow disappears or weakens by the time it flows into. Therefore, the positive pressure hp does not occur in the portion of the intake port 42, or the value becomes small even if it occurs.
[0113]
A modification of the ninth embodiment of the present invention will be described with reference to FIG. A slit 51a is formed instead of the intake port 42 in the case of FIG. That is, the suction pipe 31 has an annular air chamber 50 surrounding the inner wall thereof and having one end of the air pipe 40 connected thereto. Are formed in a slit shape. The width of the slit 51a may be 0.005 to 0.05 Da.
[0114]
With this configuration, air flows uniformly from the slit 51a into a flow without a swirling flow flowing into the suction pipe 31 through the hole 83 of the inner cylinder 81.
[0115]
In this embodiment, a plate-like stay 84 may be provided between the inner cylinder 81 forming the nozzle and the inner wall of the suction pipe 31. In such a configuration, the plate-like stay not only reinforces the inner cylinder 81, but also can rectify the flow flowing backward in the inner cylinder space 81a. Such a stay 84 may have a thickness of 0.01 to 0.1 Da.
[0116]
The diameter of the narrowest portion of the tapered nozzle may be 0.7 to 0.9 Da. Further, the axial length from the lower end of the intake port 42 or the slit 51a to the narrowest portion of the tapered nozzle is preferably 0.1 to 0.3 Da.
[0117]
Next, a tenth embodiment of the present invention will be described with reference to a partial sectional view of FIG. In this drawing, the suction pipe 31 and the air pipe 40 are extracted and shown.
[0118]
As shown in FIG. 13A, a slit 51 a is formed in the inner wall of the suction pipe 31 as an intake port communicating the annular air chamber 50 and the suction pipe 31, and the pressure in the suction pipe 31 decreases. The air is sucked into the suction pipe 31 through the air pipe 40, the air chamber 50, and the slit 51a in accordance with the condition.
[0119]
The suction pipe 31 has an inner cylinder 81 between the impeller 20 and the slit 51a. The inner cylinder 81 forms an annular inner cylinder space 80 between the inner cylinder 81 and the inner wall of the suction pipe 31. A support plate 84a that connects the inner cylinder 81 and the inner wall of the suction pipe 31 is arranged in the inner cylinder space 80. The inner cylinder space 80 is open to the flow path 36 near the slit 51a on the upstream side, and is open facing the impeller 20 on the downstream side. Here, the terms “upstream” and “downstream” refer to the main flow in the flow path 36. Since the flow in the inner cylinder space 80 may flow backward, strictly speaking, the relationship between the upstream and the downstream is reversed at that time, but it is defined as the main flow for convenience.
[0120]
The support plate 84a supports the inner cylinder 81 and also functions as a water guide plate for guiding the flow of water.
[0121]
With this configuration, the backflow from the outer peripheral side of the impeller 20 flows into the inner cylinder space 80, and the mainstream flowing on the center side of the flow path 36 and the backflow are separated by the inner cylinder 81. Therefore, the swirling flow in the suction pipe 31 is prevented.
[0122]
A modification of this embodiment will be described with reference to FIG. In this example, columns 84b are formed in the slit 51a to connect the inner wall of the suction pipe 31 at the upstream side and the downstream side across the slit 51a. The inner cylinder 81a is also formed so as to cover the slit 51a. That is, the inner cylinder and the support plate in the case of FIG. 13A extend vertically downward, and straddle the slit 51a.
[0123]
With this configuration, since the inner cylinder 81a covers the slit 51a and the support plate 84b also covers the slit 51a, no swirling flow is generated at the slit 51a.
[0124]
In this example, the inner cylinder 81a may be further extended upstream (downward in the vertical direction), expanded in a bell mouth shape, and connected to the inner wall of the suction pipe 31. At this time, a hole is made near the connecting portion of the inner cylinder 81a to the inner wall of the suction pipe 31. With this configuration, the swirling flow can be more effectively prevented.
[0125]
Next, a vertical pump according to an eleventh embodiment of the present invention will be described with reference to the partial cross-sectional view of FIG. This vertical pump utilizes a so-called treatment. The treatment is also referred to as a casing treatment. When the pump is operated in the partial flow region, the backflow comes back from the outer periphery of the inlet of the impeller 20 to the suction pipe 31, but the backflow is prevented. Therefore, it is a return flow passage having an axial length, which is provided to allow the backflow to pass through the casing at the inlet blade end portion of the impeller 20.
[0126]
In the eleventh embodiment shown in FIG. 14 (a), a treatment is formed by enlarging the portion of the suction pipe 31 immediately before the entrance of the impeller 20 toward the outside toward the outside. The portion of the suction pipe 31 immediately before the entrance of the impeller 20 has an inner wall parallel to the axial direction. At the same diameter position as the inner wall of the suction pipe, the inner wall of the suction pipe before expansion is left as it is as the inner cylinder 31a. The expanding outer peripheral portion 31 e of the suction pipe 31 expands to the same diameter as the outer peripheral portion of the air chamber 50. The enlarged outer peripheral portion 31e forms a cylindrical casing integrally with the outer peripheral portion of the air chamber 50. An annular space 31f is formed between the enlarged outer peripheral portion 31e and the remaining inner cylinder 31a. The air chamber 50 is formed in the same manner as in the above embodiment. The space 31f and the air chamber 50 are separated by an air chamber upper wall 50b.
[0127]
The inner cylinder 31a is connected to the air chamber 50, and as a result, the inner cylinder 31a and the inner wall of the air chamber 50 form a continuous inner wall. A hole 31b communicating the annular space 31f with the inside of the suction pipe 31 is formed in the connection part of the air chamber 50 of the inner cylinder 31a. A plurality of holes 31b are formed and arranged evenly in the circumferential direction.
[0128]
In such a structure, when a backflow that flows from the inlet end of the impeller 20 to the suction side occurs, the backflow flows outward due to the swirling component. Therefore, the backflow flows into the space 31f and joins the main flow at the center of the suction pipe 31 from the hole 31b. In this manner, the swirling flow in the slit 51a is suppressed, so that the positive pressure can be reduced.
[0129]
A modification of the eleventh embodiment will be described with reference to FIG. In this example, the plurality of holes 31b in the case of FIG. 14A are replaced with slits 31d formed in the circumferential direction. Further, a plurality of (preferably 2 to 16) stays 85b for connecting and supporting the inner cylinder 31c corresponding to the inner cylinder 31a with the casing outer peripheral portion 31e are provided. The stay 85b has a flat plate shape and is formed linearly in the axial direction. Therefore, it also has the function of a rectifying plate for rectifying the backflow flowing through the space 31f.
[0130]
In such a structure, when a backflow that flows from the inlet end of the impeller 20 to the suction side occurs, while the backflow flows through the space 31f as in the example of FIG. Decrease.
[0131]
In the slit 51a, a strut 52b may be formed across the slit to connect the inner cylinder 31c and the inner wall of the suction pipe 31. That is, a support (radial support, inclined support, support protruding inward) as described in FIG. 11 may be provided.
[0132]
Next, a twelfth embodiment of the present invention will be described with reference to the partial cross-sectional view of FIG. This embodiment is the same as the other embodiments except for the structure of the suction pipe 31, and is not shown. As shown in the figure, a suction pipe 31 forming a flow path 36 for flowing water toward the impeller 20 is provided with an air pipe 40 for introducing air into the suction pipe 31 from one end.
[0133]
The suction pipe 31 has an inner cylinder 91 that forms an annular inner cylinder space 92 between itself and the inner wall thereof. The inner cylinder space 92 is opened on the downstream side (vertically upward) so as to face the impeller 20. I have. An intake port 42 to the suction pipe 31 by the air pipe 40 is opened in the inner cylinder 91, and air flows into the suction pipe 31 through the air pipe 40 and the intake port 42 in accordance with a decrease in pressure of the opening in the inner cylinder 91. It is configured to inhale.
[0134]
Here, a stay as a support member for connecting the inner cylinder 91 and the inner wall of the suction pipe 31 is arranged in the inner cylinder space 92. The air pipe 40 may pass through the inside of the stay 92a, or may pass through the inner cylinder space 92 separately from the stay 92a.
[0135]
Further, as shown in FIG. 15 (b), the suction pipe 31 is formed in a bell mouth shape so that the upstream side of the inner cylinder 91 extends to the lower end of the suction pipe 31 along the bell mouth. May be. With this configuration, when a backflow occurs, the backflow flows out of the suction pipe 31 after eliminating the swirling component.
[0136]
As described above, since the backflow from the impeller 20 flows through the inner cylinder space 92, no positive pressure is generated near the intake port 42, or the pressure can be suppressed to a small positive pressure.
[0137]
【The invention's effect】
As described above, according to the present invention, suction of suspended matter in water from the air pipe to the suction pipe is prevented, the opening of the air pipe is not blocked by the floating matter, and the air is reliably sucked into the suction pipe. It is possible to provide a vertical shaft pump.
[Brief description of the drawings]
FIG. 1 is a front sectional view of a vertical shaft pump according to a first embodiment of the present invention.
FIG. 2 is a partial cross-sectional view illustrating a relationship between each water level and a water level Lc at which air is sucked in a swirl from a lower end of a suction pipe.
FIG. 3 is a partial front view showing a modification of the first embodiment of the present invention.
FIG. 4 is a partial front view showing a second embodiment of the present invention.
FIG. 5 is a sectional view of a vertical shaft pump according to a third embodiment of the present invention.
FIG. 6 is a partial front view of a vertical shaft pump according to a fourth embodiment of the present invention.
FIG. 7 is a partial front view of a vertical pump according to a fifth embodiment of the present invention.
FIG. 8 is a sectional view of a vertical pump according to a sixth embodiment of the present invention.
FIG. 9 is a QH curve (performance curve) illustrating characteristics of the vertical shaft pump.
FIG. 10 is a cross-sectional view of a vertical pump explaining a seventh embodiment of the present invention.
FIG. 11 is a partial sectional view of a vertical pump according to an eighth embodiment of the present invention.
FIG. 12 is a partial sectional view of a vertical shaft pump according to a ninth embodiment of the present invention.
FIG. 13 is a partial sectional view of a vertical shaft pump according to a tenth embodiment of the present invention.
FIG. 14 is a partial sectional view of a vertical pump according to an eleventh embodiment of the present invention.
FIG. 15 is a partial sectional view of a vertical pump according to a twelfth embodiment of the present invention.
FIG. 16 is a front sectional view of a conventional vertical pump.
[Explanation of symbols]
1 aquarium
10 Vertical pump
20 impeller
21 Rotation axis
30 casing
31 Suction pipe
31a, 31c Suction pipe inner cylinder
31b hole
31d slit
31e outer periphery
31f Space between suction pipe inner wall and casing
32 liner casing
33 Pumping pipe casing
34 Discharge piping
35 Guide casing
36 channels
40 air tube
41 Air tube opening
42 Inlet
43 Equipment to block suspended matter
44 Strainer
45 Breezer
46 Air gap between breather and air pipe
47 Air Pipe Roof Enclosure
50 air chamber
50a Air chamber wall
51a slit
52 slit
52a prop
70 Rotation prevention plate
80 Inner cylinder space
81 inner cylinder
82 Water flow path inside inner cylinder
83 Hole that connects the inner cylinder space and the water flow path inside the inner cylinder
84a, 84b Inner cylinder stay
85a treatment casing
85b treatment stay
91, 93 inner cylinder
92 Inner cylinder space
92a Inner tube stay
h Negative pressure head
HWL high water level
Ld Design water level (design water level for full discharge)
LWL Minimum operating water level
Lc Water level that draws air in a vortex
LO Water level at which water is sucked into the suction pipe through the air pipe
SLWL Impeller suction start water level
A1 intake water level
A2 Suction pipe bottom water level

Claims (12)

An impeller which is rotated by a rotating shaft arranged in a longitudinal direction and sucks water;
A suction pipe arranged upstream of the impeller and for flowing the water toward the impeller;
One end is connected to the suction pipe, and the other end is at a position lower than the highest water level of the sucked water, and below that, even when the lower end of the suction pipe is lower than the water level of the sucked water. An air pipe opening at a position higher than a minimum water level at which air is sucked from a lower end of the suction pipe;
The opening direction of the air tube is horizontal or downward from the horizontal;
Vertical pump. The vertical shaft pump according to claim 1, wherein the other end of the air pipe is formed in an inverted U shape, and the opening direction is downward. An impeller which is rotated by a rotating shaft arranged in a longitudinal direction and sucks water;
A suction pipe arranged upstream of the impeller and for flowing the water toward the impeller;
One end is connected to the suction pipe, and the other end is at a position lower than the highest water level of the sucked water, and below that, even when the lower end of the suction pipe is lower than the water level of the sucked water. An air pipe opening at a position higher than a minimum water level at which air is sucked from a lower end of the suction pipe;
The other end of the air tube was provided with a device for blocking suspended matter;
Vertical pump. The device for blocking the float is a strainer;
The vertical shaft pump according to claim 3. The device for blocking the suspended matter is a breather;
The vertical shaft pump according to claim 3. The suction tube is configured to flush water along the inner wall toward the impeller;
An intake port is formed in the inner wall, and the air pipe communicates with the inside of the suction pipe through the intake port, and sucks air into the suction pipe through the air pipe and the intake port according to a pressure drop in the suction pipe. Is configured as;
A turning prevention plate is formed on the inner wall between the impeller and the intake port to prevent turning of water due to rotation of the impeller;
The vertical shaft pump according to claim 1. The suction pipe is configured to flow water along the inner wall toward the impeller, and has an annular air chamber surrounding the inner wall;
One end of the air tube is connected to the air chamber;
An intake port is formed in the inner wall, the air chamber communicates with the inside of the suction pipe by the intake port, and air flows into the suction pipe through the air pipe and the intake port according to a decrease in pressure in the suction pipe. Configured to inhale;
A turning prevention plate is formed on the inner wall between the impeller and the intake port to prevent turning of water due to rotation of the impeller;
The vertical shaft pump according to claim 1. The suction pipe is configured to flow water along the inner wall toward the impeller, and has an annular air chamber surrounding the inner wall;
One end of the air tube is connected to the air chamber;
An intake port is formed in the inner wall, the air chamber communicates with the inside of the suction pipe by the intake port, and air flows into the suction pipe through the air pipe and the intake port according to a decrease in pressure in the suction pipe. Configured to inhale;
An air guide plate that guides air flowing from the air chamber toward the inside of the suction pipe is disposed at the intake port;
The vertical shaft pump according to claim 1. The suction tube is configured to flush water along the inner wall toward the impeller;
An intake port is formed on the inner wall, and the air pipe communicates with the inside of the suction pipe through the intake port, and air flows into the suction pipe through the air pipe and the intake port according to a decrease in pressure in the suction pipe. Configured to inhale;
The suction pipe has an inner cylinder that forms an annular inner cylinder space between the inner wall and the inner wall, between the impeller and the intake port, and the upstream side of the inner cylinder is near the intake port. Connected to the inner wall, the inner cylinder forms a tapered nozzle having a smaller flow area along the flow of the water, and the inner cylinder space is opened facing the impeller on the downstream side, A hole is formed in the vicinity of a connection portion of the inner cylinder with the inner wall, the hole communicating the inner cylinder space and a flow path of water inside the inner cylinder;
The vertical shaft pump according to claim 1. The suction pipe is configured to flow water along the inner wall toward the impeller, and has an annular air chamber surrounding the inner wall;
One end of the air tube is connected to the air chamber;
A slit-shaped intake port is formed in the inner wall, and the air chamber communicates with the inside of the suction pipe through the intake port, and the air pipe and the intake pipe pass through the air pipe and the intake port in response to a decrease in pressure in the suction pipe. Configured to inhale air into the
The suction pipe has an inner cylinder that forms an annular inner cylinder space between the impeller and the intake port and the inner wall, and the inner cylinder and the inner wall include the inner cylinder space. A support plate for connecting the inner cylinder space, the inner cylinder space is opened to the flow passage near the intake port on the upstream side, and is opened facing the impeller on the downstream side;
The vertical shaft pump according to claim 1. The suction pipe is configured to flow water along the inner wall toward the impeller, and has an annular air chamber surrounding the inner wall;
One end of the air tube is connected to the air chamber;
On the inner wall, a slit-shaped intake port communicating the annular air chamber and the suction pipe is formed over the entire circumference of the suction pipe, and the air pipe and the intake port are formed in response to a decrease in pressure in the suction pipe. Configured to draw air into the suction tube through
A casing treatment is formed between the inlet and the impeller;
The casing treatment is configured to include the inner wall and an outer casing disposed outside the inner wall, and a space between the inner wall and the outer casing, one of which is open to an inlet blade end portion of the impeller. And the other constitutes a return passage having an axial length, which is open in the vicinity of the intake port;
The vertical shaft pump according to claim 1. The suction tube is configured to flush water along the inner wall toward the impeller;
The suction pipe has an inner cylinder that forms an annular inner cylinder space between the suction pipe and the inner wall, and the inner cylinder space is open on a downstream side so as to face the impeller;
An intake port of the air pipe to the suction pipe is opened in the inner cylinder, and the air is sucked into the suction pipe through the air pipe and the intake port in response to a decrease in pressure of the opening in the inner cylinder. Composed;
The vertical shaft pump according to claim 1.

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