JP4463484B2 - Vertical shaft pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vertical shaft pump, and more particularly to a vertical shaft pump suitable for a prior 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 below the minimum operation level LWL of the suction water tank 1. There was a vertical pump 3 that allowed it to continue. In this pump 3, h≈v from the water level LWL to the suction pipe 4 upstream of the impeller 2.²An intake hole 5 penetrating the position LLWL lower by / 2g is provided, and an air pipe 6 having an opening 6a at the other end above the attachment 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 acceleration of gravity. 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 in through the holes 5, thereby avoiding a sudden pumping stop 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 start of rapid pumping is avoided by reducing the amount of drainage by the air flowing in through the holes 5 until the water level reaches the minimum operating water level LWL. Yes.
[0003]
In this way, for example, for rainwater drainage in large cities, the pump is started in advance according to rainfall information etc. regardless of the suction water level, and when the water level rises from the low water level, the total amount is increased while gradually increasing the water amount from the idle operation When the water level dropped from the high water level to the operation, it was possible to smoothly shift the operation from the full operation to the empty operation while gradually reducing the water amount. Such a pump is started at a water level LLLWL lower than the lower end of the casing (see, for example, 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, the air pipe attached to the conventional pump has a problem that it is easy to suck in floating substances in the water, and the opening is blocked by the floating substances, making it difficult for air to flow into the suction pipe. In particular, suspended matters in the water often float on the surface, so when the water level drops, the suspended matter closes the opening before the opening begins to be exposed to the air, and the water level is below the minimum operating water level LWL. Even if it becomes, there existed a problem that it became difficult to inflow of air in a suction pipe.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vertical shaft pump that is particularly suitable for a prior standby operation, in which air pipe opening is prevented from being blocked by suction of floating substances and air is surely flowed into the suction pipe.
[0007]
[Means for Solving the Problems]
  In order to achieve the above object, claim 1 is provided.To claim 5As shown in FIG. 1, for example, the vertical shaft pump 10 according to the invention is rotated by a rotary shaft 21 arranged in a vertical direction to suck in water; an impeller 20 that is arranged upstream of the impeller 20; A suction pipe 31 for flowing water toward the vehicle 20; one end of the suction pipe 31 is connected, and the other end is lower than the highest water level HWL of the water to be sucked, and below that, the lower end of the suction pipe 31 is An air pipe 40 that opens at a position higher than the lowest water level LWL that sucks air from the lower end of the suction pipe 31 even when the level is lower than the level of the water to be sucked in; Or it is downward from the horizontal.
[0008]
If comprised in this way, since the opening part of an air pipe is made into horizontal or downward from horizontal, it becomes difficult to inhale the suspended | floating matter in the water which often floats on the surface compared with upward opening.
[0009]
  Claim6And, for example, as shown in FIG.Thru | or any one of Claim 5In the vertical shaft pump described in 1), the other end of the air pipe 40 is formed in an inverted U shape, and the opening direction is the lower side.
[0010]
With this configuration, since the opening of the air pipe faces downward, it becomes more difficult to suck in floating matter, and even if floating matter sucks into the opening, it becomes easy to fall as the water level decreases. .
[0011]
  In order to achieve the object, the claims7 to 11As shown in FIG. 5, for example, the vertical shaft pump 10 according to the invention is rotated by a rotary shaft 21 arranged in a vertical direction, and an impeller 20 that sucks water; disposed on the upstream side of the impeller 20, A suction pipe 31 for flowing the water toward the vehicle 20; one end of the suction pipe 31 is connected, and the other end is lower than the highest water level HWL of the water to be sucked, and below that, the lower end of the suction pipe 31 An air pipe 40 that opens at a position higher than the lowest water level LWL that sucks air from the lower end of the suction pipe 31 even when the water level is lower than the surface of the water to be sucked; floating at the other end of the air pipe 40 A device 43 that shuts off an object is provided.
[0012]
When configured in this way, since a device for blocking floating substances is provided, the apparatus for blocking floating substances prevents infiltration of floating substances in the water into the air pipe, and suspended substances are not sucked. It is also possible to prevent the opening from being blocked by suspended matter.
[0013]
  Claim12And, for example, as shown in FIG.Any one of claims 7 to 11In the vertical shaft pump described in (1), the strainer 44 may be a device for blocking floating matter in the air pipe 40.
[0014]
In this configuration, since the strainer is provided, the strainer prevents the floating substance in the water from entering the air pipe, and the floating substance is not sucked, so that the opening may be blocked by the floating substance. Is prevented.
[0015]
  And claims13And for example as shown in FIG.Any one of claims 7 to 11In the vertical shaft pump described in 1), the breather 45 may be a device for blocking floating matter in the air pipe. The breather is a cover having an air gap 46 around the air pipe 40, and blocks the inflow of water from the side and the upper part of the breather 45 to the air pipe 40. The breather lower 45a and the breather 45 A gap 46 between the air pipes 40 is used as a water inflow path to the air pipe opening 41.
[0016]
If comprised in this way, since breather is provided, when water flows in into an air pipe, since water flows in from the lower part of a breather, inhalation of floating substance which floats on the surface is prevented, and floating substance As a result, the opening is prevented from being blocked by the suspended matter.
[0017]
StandingIn the axial pump 10, for example, as shown in FIG. 8, the suction pipe 31 is configured to allow water to flow toward the impeller 20 along the inner wall; an intake port 42 is formed in the inner wall; The air pipe 40 communicates with the inside of the suction pipe 31 through the air inlet 42, and is configured to suck air into the suction pipe 31 through the air pipe 40 and the air inlet 42 in response to a pressure drop in the suction pipe 31; On the inner wall between the air inlet 42 and the air inlet 42, a turning prevention plate 70 for preventing water turning due to the rotation of the impeller 20 is formed.May.
[0018]
If comprised in this way, since a rotation prevention board is provided, the swirl flow around the axis | shaft in a suction pipe can be prevented, the positive pressure in the inner wall of the suction pipe by the said swirl flow does not arise, and an air pipe is opened from an opening part. The air is sucked into the suction pipe through the intake port according to the water level and the flow speed in the suction pipe.
[0019]
  further, StandingIn the shaft pump 10, for example, as shown in FIG. 10, the suction pipe 31 is configured to flow water toward the impeller 20 along the inner wall, and has an annular air chamber 50 surrounding the inner wall. 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, and the pressure in the suction pipe 31 decreases. Accordingly, air is sucked into the suction pipe 31 through the air pipe 40 and the intake port 42; the inner wall between the impeller 20 and the intake port 51a is swirled with water by the rotation of the impeller 20. An anti-rotation plate 70 is formed to preventMay.
[0020]
If comprised in this way, since a rotation prevention board is provided, the swirl flow around the axis | shaft in a suction pipe can be prevented, the positive pressure in the inner wall of the suction pipe by the said swirl flow does not arise, and an air pipe is opened from an opening part. The air is sucked into the suction pipe through the intake port according to the water level and the flow speed in the suction pipe, and since the annular air chamber is provided, the air can be uniformly distributed on the inner wall of the suction pipe.
[0021]
StandingIn the axial pump, 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 air chamber 50 surrounding the inner wall; 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, so that the pressure in the suction pipe 31 is reduced. Accordingly, air is sucked into the suction pipe 31 through the air pipe 40 and the suction port 52; the air guide plates 52a to 52d guide the air flowing from the air chamber 50 toward the suction pipe 31 to the suction port 52. 52d is placedMay.
[0022]
If comprised in this way, since the annular air chamber 50 and the air guide plates 52a-52d of a slit are provided, the flow of air will become uniform and the effect of attracting air into water will be effective according to the shape of a guide plate.
[0023]
  Claim 3 andIn the vertical shaft pump according to the ninth aspect of the present invention, for example, as shown in FIG. 12, 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 air inlet 42 so that air is sucked into the suction pipe 31 through the air pipe 40 and the air inlet 42 in accordance with a decrease in the pressure in the suction pipe 31. The suction pipe 31 has an inner cylinder 81 that forms an annular inner cylinder space 80 between the inner wall and the impeller 20 and the air inlet 42, and the upstream side of the inner cylinder 81 is Connected to the inner wall in the vicinity of the air inlet 42, the inner cylinder 81 forms a tapered nozzle whose flow area decreases along the flow of water, and the inner cylinder space 80 faces the impeller 20 on the downstream side. In the vicinity of the connecting portion of the inner cylinder 81 with 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 between the inner wall and the impeller between the impeller and the intake port, and the upstream side of the inner cylinder is in the vicinity of the intake port. Connected to the inner wall, the inner cylinder forms a tapered nozzle that reduces the flow path area along the flow of water, and the inner cylinder space is opened facing the impeller on the downstream side. The reverse flow flows into the inner cylinder space, and since a hole is formed in the vicinity of the connection portion of the inner cylinder with the inner wall, the reverse flow flows out of the hole. To do. In this way, the swirl flow due to the reverse flow is suppressed.
[0025]
  Claim 4 andIn the vertical pump according to the invention according to claim 10, for example, as shown in FIG. 13, the suction pipe 31 is configured to flow water toward the impeller 20 along the inner wall, and annular air surrounding the inner wall. A chamber 50; one end of the air pipe 40 is connected to the air chamber 50; a slit-like air inlet 51a is formed in the inner wall, and the air chamber 50 communicates with the inside of the suction pipe 31 by the air inlet 51a. The suction pipe 31 is configured to suck air into the suction pipe 31 through the air pipe 40 and the suction port 51a in accordance with a decrease in the pressure in the suction pipe 31; the suction pipe 31 is disposed between the impeller 20 and the suction port 51a. An inner cylinder 81 forming an annular inner cylinder space 80 is formed between the inner wall and the inner cylinder space 80. A support plate 84a for connecting the inner cylinder 81 and the inner wall is disposed in the inner cylinder space 80. It is 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 support the inner cylinder 81 and function as a water guide plate that guides the flow of water.
[0026]
If comprised in this way, since it has an inner cylinder which forms a cyclic | annular inner cylinder space between inner walls, the backflow from an impeller flows through an inner cylinder space. In addition, since a 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. Further, the support plate can be configured to function as a water guide plate for guiding the flow of water, and at that time, the flow of water can be rectified.
[0027]
  Claim 5 andIn the vertical shaft pump according to the invention according to claim 11, 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 annular air surrounding the inner wall. A chamber 50; one end of the air pipe 40 is connected to the air chamber 50; a slit-like air inlet 51a communicating the annular air chamber 50 and the suction pipe 31 is formed on the inner wall over the entire circumference of the suction pipe 31. It is formed and 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; 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]
If comprised in this way, since a suction pipe has a casing treatment, the backflow from an impeller will flow through a casing treatment and the swirling flow by a backflow will be suppressed.
[0029]
  ClaimClaims 1 and 2 and Claims 7 and 8In the vertical shaft pump according to the invention, for example, as shown in FIG. 15, the suction pipe 31 is configured to flow water toward the impeller 20 along the inner wall; the suction pipe 31 is between the inner wall and the suction pipe 31. The inner cylinder space 92 has an inner cylinder 91 that forms an annular inner cylinder space 92, and the inner cylinder space 92 is opened on the downstream side so as to face the impeller 20; It opens in the pipe | tube 91, and it is comprised so that air may be suck | inhaled in the suction pipe 31 through the air pipe 40 and the inlet port 42 according to the fall of the pressure of the opening part in the inner cylinder 91. FIG.Further, in the vertical shaft pump according to the inventions according to claim 1 and claim 7, the upstream side of the inner cylinder is opened in the inner wall or at the lower end of the inner wall. Further, the vertical shaft pump according to the inventions according to claim 2 and claim 8 is configured such that the inner cylindrical space allows a backflow from the impeller to flow when the amount of water downstream of the impeller is smaller than the design point. ing.
[0030]
Typically, a support member 92 a that connects the inner cylinder 91 and the inner wall is disposed in the inner cylinder space 92. The air pipe 40 may penetrate the inside of the support member 92a, or may penetrate the inner cylindrical space 92 separately from the support member 92a.
[0031]
If comprised in this way, since the backflow from an impeller flows through inner cylinder space, a positive pressure does not generate | occur | produce near an inlet port easily.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol or a similar code | symbol is attached | subjected to the mutually same or equivalent member, and the overlapping description is abbreviate | omitted.
[0033]
With reference to the sectional view of FIG. 1, a vertical shaft pump according to a first embodiment of the present invention will be described. The vertical shaft pump 10 is a pump for preceding standby operation.
[0034]
Pre-standby operation, especially full-speed pre-standby operation, starts the pump in advance before rainwater flows into the pump water tank, starts draining as the water level rises, and even if the water level drops, the pump does not stop Is to drive at. Even if drainage is started, the vertical shaft pump 10 does not immediately discharge the water amount of the essential point. In order to enable operation without discharging the amount of point water, air is sucked in together with water.
[0035]
The structure of the vertical shaft pump 10 will be described with reference to the drawings. The vertical shaft pump 10 includes a pumping pipe casing (casing body) 33, a liner casing 32, and a suction pipe (suction bell) 31 arranged in the vertical direction from above. Each is fastened with a horizontal flange. These constitute a casing in a broad sense.
[0036]
A rotary shaft 21 is arranged in the longitudinal direction (vertical direction) at the center of the casing, and an open impeller 20 is attached to the lower end of the rotary shaft 21 (may be a closed type). The liner casing 32 accommodates the impeller 20 with a slight gap from the outer periphery of the impeller 20 (the tip of the open blade). The vertical shaft pump 10 is a mixed flow pump. A mixed flow pump is used when the discharge head is relatively large. A guide vane 35 is disposed on the discharge side of the impeller 20 and on the inner side of the casing body 33.
An axial flow pump (not shown) may be used as the pump for the preceding standby operation. The axial flow pump is suitable when the flow rate is relatively large with respect to the discharge head.
[0037]
The casing body 33 is configured to include a vertical can body portion parallel to the rotation shaft 21, a bent tube portion bent in the horizontal direction above, and a horizontal tube portion connected thereto, and the bent tube portion is connected to the rotation shaft 21. Has penetrated. A bearing 22c and a seal (not shown) are disposed in the through portion. The rotating shaft is supported at three points by a bearing 22a and the bearing 22c disposed in the vicinity of the impeller 20, and a bearing 22b disposed between the two bearings. In addition, a thrust bearing (not shown) supports a load in the vertical direction applied to the rotating shaft 21 (that is, the weight of the rotating body including the impeller 20 and the rotating shaft 21 and the fluid force applied to the impeller 20).
[0038]
A flange for installation is attached to the casing main body 33, and the flange 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 is connected to the discharge pipe 34 by the flange. The discharge pipe 34 is a pipe for guiding rainwater to a river or the sea and discharging it.
[0039]
An intake port 42 is formed in the suction 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 in the water tank 1 and higher than the lowest water level LWL, and horizontally or downward. In the present embodiment, the other end of the air tube 40 is formed in an inverted U shape, and the opening direction is downward in the vertical direction. Here, the minimum water level LWL is below that, even if the lower end of the suction pipe 31 is at a position lower than the surface of the water to be sucked, that is, the water surface in the water tank 1, air is sucked from the lower end of the suction pipe 31. The water level. In other words, even if the suction pipe 31 goes below the water surface, it is a water level that sucks air in a spiral shape, for example. The highest 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 the number of the air pipes 40 may be one as shown in the drawing, the number of the air pipes 40 is preferably plural, for example, four because the air sucked from the air pipe 40 is distributed all around the suction pipe 31. That is, the plurality of intake ports 42 are equally distributed 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, it is submerged or exposed to the air during the operation of the vertical shaft pump 10.
[0043]
The impeller 20 is disposed below the lowest water level LWL. The entire main body part of the impeller 20 or at least a part thereof, in particular, the tip end portion of the impeller 20 that sucks up water if there is a water level there, is disposed below the lowest 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 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 will not rise any further. Below that is the lowest water level LWL. This is a value peculiar to the pump. If the water level falls below this level, some problem occurs and the pump cannot continue to operate. Typically, below that, the air is sucked in from the lower end of the suction pipe 31 and coincides with the water level Lc where vibration and noise are generated and the operation cannot be continued. This is a value unique to the pump, and when the air pipe 40 is not provided, it becomes difficult to continue the operation if it falls below the minimum water level LWL. 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 spiral air.
[0045]
The design minimum water level Ld is at least equal to the water level LWL and is usually higher than that. The design minimum water level Ld is simply obtained from the lower end of the suction pipe 31 by multiplying the inner diameter of the suction pipe by a predetermined coefficient. For example, the coefficient is 1.1. The design value has a certain margin, and when the air pipe 40 is closed and the water level is lowered by an actual machine, the operation is possible even if the design level is slightly below the minimum water level Ld.
[0046]
Below the design minimum water level Ld or the lowest 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, the air-water stirring is started and water is discharged soon.
[0047]
There is an intake water level A1 below the suction start water level SLWL. This corresponds to the upper end of the air inlet 42. When the water level L decreases and reaches the water level LWL, the water level in the air pipe 40 that is lower than the water level L by the negative pressure h becomes the water level A1, and air begins to be sucked into the suction pipe 31 through the air pipe 40. .
[0048]
Below the intake 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 occurred in a certain area is entered, it is predicted that the water level in the aquarium 1 will suddenly rise after a certain time. In such a case, the vertical pump 10 for the preliminary standby operation is started in a state where the water level L is lower than A2. This is the start of the preceding 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 idling.
[0051]
When the water level L further rises and reaches the water level SLWL, the impeller 20 starts air-water agitation. Then begin to inhale water. At this time, air is sucked into the suction pipe 31 through the air pipe 40 and into the suction pipe 31, so that the pump is not an operation for discharging the total amount of water. That is, the vertical shaft pump 10 is in the air / water mixing operation. When the water level L further rises, the intake air amount gradually decreases, and the water amount increases instead. Eventually, when the water level L rises to the water level LWL, the air suction amount becomes zero, and the total water amount at the essential point is discharged (although it depends on H on the QH curve (described later)). That is, the steady operation is started.
[0052]
When the water level further 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 added from the lower part of the intake pipe 31 and is sucked through the air pipe 40. Also from the opening 42, it flows into the suction pipe 31. Let this water level be LO. When the length from the top of the inverted U-shape to the opening 41 (the falling length) is small, the difference between the water level LO and the water level in the air pipe opening 41 is small, Even if the water level is considered, there is no practical problem. The case where the inverted U-shaped falling length 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 lowered due to the drainage of the pump 10, the water level LO is no longer sucked from the air pipe opening 41, and the water pipe 40 no longer flows into the suction pipe 31. At the water level LWL (because the water level in the air pipe 40 reaches the inlet water level A1), the air starts to be sucked into the suction pipe 31 through the air pipe 40. That is, the air / water mixing operation is started again. As the water level L decreases, the amount of intake air increases and the amount of water decreases instead. When the water level L further decreases and reaches the vicinity of the water level A1, the suction of water is finished, and the impeller 20 enters an idle operation state in which it is operated in the air. That is, the pump 10 is in an air lock state in which no water is sucked.
[0054]
Although the airlock water level is designed so as to coincide with or be close to the water level A1 that is usually the height of the intake port, it does not always coincide. There is a case where the water amount becomes zero only when the water level further passes through A1 or 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 way, the impeller 20 continues to idle in the air. When it continues to rain, the operation is continued, the water level L rises again, and the pump 10 starts to suck water when it reaches the water level SLWL as described above. Thus, regardless of the water level of the water tank 1, the preceding standby operation pump 10 can continue operation between the idling operation and the operation of the essential point total water amount. The transition between idle operation and point-of-return full water operation is smooth as the pump also draws in air.
[0056]
As described above, even if the water level L is sufficiently lowered to be lower than the water level A2 at the lower end of the suction pipe 31, the pump 10 continues the preceding standby operation. Water stays in the casing (particularly the discharge casing 33) above the impeller 20 for about 10 minutes after the discharge water amount becomes zero, but if the state continues for a long time, the temperature of the water Rises and causes damage to the pump, so that water in the casing is drained from a drain hole (not shown). In the subsequent standby operation, the impeller 20 is idling in the air.
[0057]
As described above, the water level L in the water tank rises due to the inflow of rainwater, and even if the water level exceeds A1, the water is not yet sucked up, but while the water has accumulated above the impeller 20 immediately after the water level is lowered. When the water level rises again, water suction starts at the water level A1 which is the height of the intake port.
[0058]
A plurality of the preceding standby operation pumps as described above are usually installed in the machine. In the operation of such a machine, when the amount of drainage is insufficient with one pump as the water level increases, the other pumps are started one after another to start the operation of a plurality of units.
[0059]
Here, the relationship between each water level and the water level Lc that sucks air in a spiral shape from the lower end of the suction pipe 31 will be described.
[0060]
In general, when designing a vertical shaft pump, an airlock water level is first specified by design specifications. That is, the water level drops from a high water level, and finally drains from the water level. Normally, the airlock water level is designed to coincide with the water level A1 at the inlet. Check the airlock water level during the test run. The actual airlock water level is not higher than the intake port position, and is lower than that or approximately the same height.
[0061]
In general, the design specification also specifies a position at which drainage is started when the water level rises from a low water level, that is, the 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. Where h = hl + (v²/ 2g). In simple calculations, h = (v²/2g)×1.1.
[0063]
Here, v is a water suction flow velocity obtained by (total amount of essential points water) / (suction portion area of suction pipe 31). (V²/ 2g) is the negative pressure generated by the water flow calculated from Bernoulli's theorem. It may be called velocity head. Further, hl is a flow loss from the lower end A2 of the suction pipe 31 to the intake port. In the above simple calculation, hl = (v²/2g)×0.1, the flow loss from the lower end A2 of the suction pipe 31 to the intake port 42 is determined empirically using a coefficient. Of course, the loss head from the lower end A <b> 2 of the suction pipe 31 may be calculated or actually measured.
[0064]
The design water level Ld, which is the total amount of discharged water, is the water level calculated as described above. When the water level L tends to rise, air is not sucked from the intake port 42 here, and the pump is discharged in full amount. When the water level L is in a downward trend, the water level is such that the discharge of the entire amount ends here and the air starts to be sucked from the intake port 42.
[0065]
The design water level Ld that is the total amount of discharged water gives a margin to the water level Lc that sucks air in a spiral shape from the lower end of the suction pipe 31. Therefore, air is not sucked from the lower end of the suction pipe 31 at this water level. That is, the water level Ld is at the same level as or higher than the water level LWL, usually the water level Lc.
[0066]
Below that, the water level Lc, in which air is sucked in from the lower end of the suction pipe 31 and vibration or noise is generated and the operation cannot be continued, becomes a check item in obtaining the water level Ld as described above. That is, when the water level Ld obtained in the design process has become lower than the water level Lc, the design is corrected so that the water level Ld is equal to or higher than the water level Lc. For example, the suction pipe 31 is lengthened to lower the water level Lc. For example, the water level Ld is calculated as 1.1 × suction pipe inner diameter from the water level A2.
Experience has shown that Ld should not be 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, consider a case where 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 from the air pipe opening 41. At this time, suspended matter in the water is also sucked 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, there is a high risk of inhaling the suspended matter. When the water level L is higher than the water level LO, the air pipe opening 41 is blocked by the suspended matter, and the inflow of water from the air pipe opening 41 through the air pipe 40 and the air inlet 42 to the suction pipe 31 is blocked. However, there is no problem in the operation of the vertical shaft pump 10. However, even if the water level L falls below the water level LO, the air pipe opening 41 is exposed to the air, and even if the water level L falls below the minimum operating water level LWL, the air pipe 40 and the air inlet 42 from the air pipe opening 41. If the suction of air into the suction pipe 31 is blocked by floating substances, the operation of the vertical pump 10 is hindered as described above, for example, air is sucked in from the lower end of the suction pipe 31. It should be noted that the same result is obtained even when the water level LO matches the lowest operating water level LWL.
[0070]
The position of the air pipe opening 41 must be higher than the water level at which the air starts to be sucked into the suction pipe 31 through the air pipe 40 and the air inlet 42, that is, the lowest operating water level LWL. The air pipe becomes longer, and it becomes easy to cause damage in transportation and installation work for installing the vertical shaft pump, so that the protection of the air pipe becomes complicated. In addition, if the air pipe is long, it is uneconomical in production because the support for supporting from the casing increases. Therefore, it is preferable that the air pipe is short.
[0071]
Further, it is possible to set a water level at which the air pipe opening 41 starts to suck air into the suction pipe 31 through the air pipe 40 and the air inlet 42. At higher water levels, the air pipe opening 41 is installed at a height where it is desired to discharge the total amount of water without sucking air through the air pipe 40 and the air inlet 42. The suction of air through the air pipe 40 and the air inlet 42 is not necessarily started when the water level is equal to or lower than the water level of the air pipe opening 41, but at least the water level L is lowered to the position of the air pipe opening 41. Or if the water level L rises beyond the position of the air pipe opening 41, the total amount of water of the essential point is discharged.
[0072]
That is, the air pipe opening 41 may be submerged, and as described above, not only air but also water in the water tank 1 may be sucked. For this reason, the floating substance floating in the water is sometimes sucked, and the floating substance often floats on the water surface.
[0073]
Therefore, for example, as shown in FIG. 1, by making the air pipe opening 41 horizontal or downward from the horizontal, in particular, the opening side end is formed in an inverted U shape, and the opening direction is vertically downward, Can reduce inhalation of nearby floats. If the opening is upward, the water level is slightly higher than the water level of the opening. If the opening is downward, the surface water is sucked. There is nothing.
[0074]
In addition, in order to suck a large floating substance, the floating substance may be locked to the air pipe opening 41 and block the air pipe opening 41. In this case, when the water level drops and falls below the water level of the air pipe opening, the air pipe opening 41 is exposed to the air, and since the water level is below the water level LO, water cannot be sucked in. Absent. Then, the water flow that has locked the suspended matter to the air pipe opening disappears. If the air tube opening is downward, generally there is no force to support the suspended matter on the air tube opening 41, and the suspended material falls by gravity. Even when the suspended matter is fitted in the air pipe opening 41, it is easy to fall if the air pipe opening is downward.
[0075]
Next, a modification of the first embodiment will be described with reference to the partial view of FIG. As shown in FIG. 3A, by making the opening direction of the air tube 40 horizontal, the air tube opening 41 is locked to the air tube opening 41 than when the air tube opening 41 is facing upward, Floating matter that may block the air pipe opening 41 is likely to fall when the air pipe opening 41 is exposed in the air.
[0076]
Further, as shown in FIG. 3 (b), 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 floating substances can be prevented.
[0077]
Alternatively, as shown in FIG. 3 (c), air flows from the outer wall of the casing 30 above the air pipe opening 41 in the horizontal direction and extends forward from the air pipe opening 41, and from the entire side edge of the upper plate. It is good also as a structure which covers the air pipe opening part 41 with the roof enclosure 47 with the side plate extended below from the pipe opening part 41. FIG. Even with such a structure, a large floating object is sucked from the air pipe opening 41 by making the air pipe opening face the vertical plate and adjusting the distance between the air pipe opening 41 and the vertical plate. Can be prevented. In particular, as compared with the case where the air pipe opening 41 faces the casing 30, the air pipe 40 can be attached near the casing 30, so that it is easy to support the air pipe 40 from the casing 30, and the Installation becomes easier.
[0078]
Further, as shown in FIG. 3D, when the opening side end portion of the air tube 40 is formed in an inverted U shape and further its tip end portion becomes wider as it goes forward, the flow of the opening portion is increased. As the road area becomes larger, the flow rate of water is reduced, and it becomes difficult to suck in floating matter. In addition, since the area of the opening 41 is large, it becomes difficult to be blocked by floating matter.
[0079]
Further, as shown in FIG. 3 (e), if the opening side end of the air tube 40 is formed in an inverted U shape, and further provided with a device 43 for blocking suspended matter such as a strainer described later at the tip thereof. The floating substance floating in the inverted U-shaped opening is also blocked by the device for blocking the floating substance, and the floating substance is prevented from being sucked into the air pipe 40. When the strainer is used as the strainer, the mesh surface of the strainer may be in a direction for sucking water from the vertically downward direction, or may be sucked in from the horizontal direction.
[0080]
Next, a second embodiment will be described with reference to the partial view of FIG. This embodiment is a case where water does not flow through an air pipe formed in an inverted U shape. So far, the embodiment has been described on the assumption that there is not much difference in height between the top of the inverted U shape and the opening, but as shown in FIG. When the height to the portion 41 is made sufficiently long, water is not sucked through the air pipe 40 and the air inlet 42. As shown in FIG. 4B, when the water level L further rises after the water level L reaches the water level of the opening, the air in the air pipe 40 is confined. 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 increases, the rise in the water level in the air pipe is higher than the rise in the water level L as shown in FIG. Becomes smaller. Therefore, as shown in FIG. 4 (d), even when the maximum water level HWL is reached, the water level on the opening side in the air tube does not exceed the bottom in the tube 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 is not sucked into the suction pipe 31 through the air pipe 40 and the air inlet 42. Therefore, the suspended matter is not sucked into the opening. Note that the shape of the air tube for preventing water from being sucked in is individually determined by 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 cross-sectional view of FIG. In the present embodiment, as shown in the figure, a device 43 for blocking floating substances is provided at the end of the air tube 40 on the opening side so that the air tube 40 does not suck water in the water tank 1 directly from the opening. It has become. The device for blocking the floating material prevents the floating material from being sucked into the air pipe 40.
[0082]
Next, a fourth embodiment of the present invention will be described with reference to the partial view of FIG. In the present embodiment, as shown in the figure, 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 water flow path and captures suspended matter in running water passing through the mesh. The mesh 44a may have a structure that captures a suspended matter larger than the minimum size that obstructs the operation of the vertical pump 10 regardless of the shape, such as a slit shape or a perforated plate shape, even if it is not a mesh shape. . The strainer is installed so that the lowermost part of the mesh 44a becomes the water level LO. This is because air is sucked in only after the lowermost part of the mesh 44a is exposed to the air. In addition, in the strainer, it is preferable to increase the area of the mesh 44a so that the entire mesh 44a is not easily blocked by the suspended matter. Furthermore, 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 floating substances. In addition, when the mesh 44 a is installed vertically as shown in FIG. 6, suspended matter that is locked to the mesh 44 a while the water in the water tank 1 is sucked through the strainer 44 is also included in the strainer 44. When exposed to the air, it is easy to drop due to gravity. Therefore, when the water level drops and air is sucked into the suction pipe 31 through the strainer 44 and the air pipe 40, the suspended matter in the mesh 44a becomes an obstacle to the inflow of air. 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 in the figure, a breather 45 is provided at the end of the air tube 40 on the opening side. Here, the breather is a generally cylindrical side surface having an inner diameter larger than the outer diameter of the air tube 40 and a cap-shaped cover with the upper surface of the cylinder closed, and between the breather 45 and the air tube 40 from the lower portion 45a. The air gap 46 is used as an inflow path to the air pipe opening 41. When a breather is provided, the breather lower part 45a is installed at a level of water level at which air starts to be sucked into the suction pipe 31 through the air pipe 40. When the water level becomes lower than the breather lower part 45a, an air flow path to the air pipe opening 41 is secured for the first time, and air is sucked into the suction pipe 31 through the air pipe 40. The width of the gap between the breather inner wall and the air pipe may be 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. You may make it larger than the size of the minimum suspended matter which obstructs driving.
[0084]
Further, as shown in FIG. 7B, the side of the breather 45 may be extended from the highest water level HWL to the upper part without opening the upper part of the breather, and the upper part may be opened. In this structure, the flow path into the suction pipe 31 through the water air pipe 40 in the water tank 1 becomes the air pipe opening 41 from the breather lower part 45 a and the gap 46. The flow path of air through the air pipe 40 into the suction pipe 31 is from the opening at the top of the breather to the air pipe opening 41 through the breather and from the breather bottom 45a and the gap 46 to the air pipe opening 41. It becomes a flow path. In particular, the former air flow path is ensured even when the water level L is lower than the air pipe opening water level and higher than the height of the breather lower part 45a. That is, in such a structure, the water level of the air pipe opening is set at the water level LO.
[0085]
As shown in FIG. 7C, a water inflow hole 45 b may be formed on the side surface of the breather 45 below the air pipe opening 41. In such a structure, the flow path into the suction pipe 31 through the water air pipe 40 in the water tank 1 becomes the air pipe opening 41 from the breather lower part 45 a and the hole 46 b and the gap 46. When the water level is equal to or lower than the breather hole 45b, an air flow path to the air pipe opening 41 is secured through the air gap 46, and air can be sucked into the suction pipe 31 through the air pipe 40. The upper end of 46b is installed at the level of the water level at which air starts to be sucked into the suction pipe 31 through the air pipe 40. With such a structure, the inflow port to the inside of the breather becomes large, and the flow velocity at the inflow port becomes slow.
[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 pump discharge flow rate is near the design point, but on the small water volume side from the design point, a reverse flow 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 amount of discharged water is calculated by the water level A1 + h, and h = hl + (v²/ 2g), a positive pressure hp is actually generated in the vicinity of the air inlet 42. This is due to the swirling flow generated inside the suction pipe 31. That is, it is considered that a positive pressure is generated by the centrifugal force generated by the swirling flow.
[0088]
Considering the positive pressure hp, h is as follows.
h = hl + (v²/ 2g) -hp
[0089]
When the positive pressure hp is generated, air is not 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 in from the lower end of the suction pipe 31 to cause 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 arranged in the radial direction and in the axis (vertical direction). Formed towards. The anti-swivel plate may have an integral structure when the suction pipe 31 is made of a casting. A plurality of anti-rotation plates are provided. For example, the number is four. If the swirl prevention plate is provided, the swirl prevention plate 70 prevents swirl 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 of FIG. This figure is a diagram showing the performance of the full-speed advance standby operation pump with the vertical axis indicating the total head H (%) and the horizontal axis indicating the discharge amount Q (%). In addition to the case of steady operation where air is not sucked, the change in pump performance due to the change in air inflow is also shown.
[0092]
In the figure, curve A represents a flow rate-lift (QH) curve, curve B represents a resistance curve at the planned lift (straight line C), and curve D represents a resistance curve at the highest actual lift (straight line E). . The state of the curve D is a case where the discharge pressure varies greatly and the discharge pressure is high. A curve indicated by a two-dot chain line in a shape in which the curve A is moved in the direction of the origin is a QH curve of a steam-water mixing operation for sucking air. The intersection of each QH curve and the resistance curve is the operating point in each state.
[0093]
In the advanced standby operation pump for rainwater drainage, the height of drainage 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 difference in height between A1 and HWL is not so large, but in reality, the discharge casing 33 can be made longer, and may exceed 10 m, for example. . In such a preliminary standby operation pump, even if the essential point A is set between the water levels Ld and HWL, the resistance curve becomes like curve D when the water level becomes Ld. That is, 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 inevitably small as indicated by the point B occurs.
[0094]
A point A in FIG. 9 indicates an operation point (essential point) in the case where there is no air inflow in 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 in the direction. Point B in the figure indicates the operating point when there is no air inflow at the maximum actual head, which is an operating point on the side of a relatively small amount of water with respect to the maximum efficiency point. At this time, a reverse flow is generated on the outer peripheral side of the impeller 20, and therefore, a swirling component is generated in the pumped water in the suction pipe 31 that is swung in the rotation direction of the impeller 20 near the inner wall of the suction pipe 31. .
[0095]
The anti-swivel plate 70 described above prevents such a swirling flow, and thus has an effect of reducing the positive pressure hp. In the above description, the device for preventing swirling flow is described as a plate-shaped swirling prevention plate. However, the swirling preventing plate may be a protrusion, or a circumferential unevenness is provided on the inner wall of the suction pipe 31. An air inlet may be installed in the recess.
[0096]
Next, a seventh embodiment of the present invention will be described with reference to the cross-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 is uniformly distributed over the entire circumference of the suction pipe 31.
[0097]
The structure and operation of the air chamber will be described with reference to the enlarged view of the air chamber 50 in FIG. In FIG. 10B, the upper end of the slit 51a is formed 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 lowest water level Ld and the water level in the air pipe 40 is lowered to the opening of the air pipe 40 to the air chamber wall 50a, air is not yet sucked into the suction pipe 31. The water level L is further lowered, the water level in the air pipe 40 is further lowered by ha, and air suction starts when reaching the upper end of the slit 51a.
[0098]
Because of such a structure, if there is sufficient space above the slit 51a of the air chamber 50, 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 taken large, such an effect can be expected. If a plurality of air tubes 40 are provided and 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 in a front view, but a wave shape, a periodic notch is provided, or the like has a periodic vertical change, Since air flows uniformly from the high part into the suction pipe 31 over the entire circumference in the form of small bubbles, the 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 periphery of the air chamber 50. 11 (b), FIG. 11 (c), FIG. 11 (d), and FIG. 11 (e) are views taken along the line XX when the suction pipe is viewed at the position of the slit 52.
[0101]
In the present embodiment, a slit 52 as an air inlet, which is 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 that is 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 support column 52 a that straddles the slit 52 and connects the inner wall of the suction pipe 31 on the upstream side and the downstream side.
[0103]
As shown in FIG. 11B, in the first modification, the support columns 52 a are equally arranged in the slits 52. The support column 52a can be formed in a form that leaves a casing wall (inner wall) so as to block the slits at equal intervals. The ratio of the wall left as the column 52a and the slit as the communication port may be such that the total opening of the slit may be larger than the total of the column 52a. The circumferential length of each of the openings is preferably 0.1 times or less of the inner diameter Da of the suction pipe 31 in the slit forming portion.
[0104]
Further, as shown in FIG. 11 (c), the support column may constitute an air guide plate 52 b that guides the air flowing from the air chamber 50 toward the suction pipe 31. If comprised in this way, since the flow of air can be directed to radial direction, there exists an effect which reduces the swirl | vortex flow in the suction pipe 31. FIG.
[0105]
Further, as shown in FIG. 11 (d), the air guide plate 52c may be inclined in the water turning direction with respect to the radial direction. If comprised in this way, there exists an effect which attracts the air sucked in to rotation of water, and makes it easy to inhale air irrespective of a swirl flow.
[0106]
Further, as shown in FIG. 11 (e), the air guide plate 52d is inclined in the water swirling direction with respect to the radial direction, and the tip of the air guide plate 52d is moved to the casing (in this embodiment, the suction pipe 31). You may make it protrude rather than the inner surface. If comprised in this way, there exists an effect which weakens a swirl flow other than the effect of attracting the sucked air to the swirl of water. The protruding amount is preferably about 0.1 times or less than the inner diameter of the suction pipe 31 toward the center of the suction pipe 31.
[0107]
The column or guide plate has the effect of supporting the weight of the portion below the slit of the suction pipe 31 in addition to guiding air.
[0108]
In FIG. 11, the eighth embodiment is described as including the anti-rotation plate 70 in addition to the slit with the support column, but the anti-rotation plate 70 may be omitted in view of the air attraction effect of the slit with the support column. . In particular, in the case of the modification described with reference to FIGS. 11D and 11E, the rotation preventing plate 70 can be omitted.
[0109]
In the eighth embodiment, the axial width of the slit 52 is preferably 0.005 to 0.05 times the diameter of the suction pipe 31. Moreover, the width | variety of the support | pillar 52a has a thickness 0.005-0.05 times the diameter of a 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 equal to the inner diameter of the suction pipe 31 at the mounting position of the backflow prevention plate 70. It is preferable to make it 0.1 times or less. Moreover, 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 a partial sectional view of FIG. In this embodiment shown in FIG. 12A, the suction pipe 31 has an inner cylinder 81 that forms an annular inner cylinder space 81a between the inner wall and the impeller 20 and the air inlet 42. is doing. The inner cylinder 81 is connected to the inner wall at the upstream side, that is, vertically below, in the vicinity of the air inlet 42, and the inner cylinder 81 forms a tapered nozzle whose flow path area decreases along the flow of water. The inner cylinder space 81a is opened facing the impeller 20 on the downstream side. In the vicinity of the connection portion of the inner cylinder 81 with the inner wall of the suction pipe 31, a hole 83 that connects the inner cylinder space 81 a and the water flow path 82 inside the inner cylinder is formed.
[0112]
If comprised in this way, the flow which flows backward on the outer peripheral side of the impeller 20 in a small flow rate area will flow in between the inner cylinder 81 which forms a nozzle, and the inner wall of the suction pipe 31, and the suction pipe 31 will pass through the hole 83. The swirl flow disappears or weakens before it flows into Therefore, the positive pressure hp does not occur in the portion of the intake port 42 or even if it occurs, it becomes a small value.
[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 air inlet 42 in the case of FIG. That is, the suction pipe 31 has an annular air chamber 50 that encloses the inner wall of the suction pipe 31 and is connected to one end of the air pipe 40. The suction pipe 31 extends along the air chamber 50 so that the air chamber 50 and the suction pipe 31 communicate with each other. Is formed in a slit shape. The width of the slit 51a is preferably 0.005 to 0.05 Da.
[0114]
If comprised in this way, air will flow in uniformly from the slit 51a in the flow without a swirl flow which flows 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 can reinforce the inner cylinder 81 and can rectify the flow that flows backward through 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 part of the tapered nozzle is preferably 0.7 to 0.9 Da. Further, the axial length from the lower end of the air inlet 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 figure, the suction pipe 31 and the air pipe 40 are extracted and shown.
[0118]
As shown in FIG. 13 (a), the inner wall of the suction pipe 31 is formed with a slit 51 a as an air inlet that communicates the annular air chamber 50 and the suction pipe 31, and the pressure in the suction pipe 31 decreases. Accordingly, the air is sucked into the suction pipe 31 through the air pipe 40, the air chamber 50, and the slit 51a.
[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 wall of the suction pipe 31. A support plate 84 a that connects the inner cylinder 81 and the inner wall of the suction pipe 31 is disposed in the inner cylinder space 80. The inner cylinder space 80 is opened to the flow path 36 in the vicinity of the slit 51a on the upstream side, and is opened facing the impeller 20 on the downstream side. Here, upstream and downstream refer to the main flow of the flow path 36. Since the flow in the inner cylinder space 80 may flow in the reverse direction, strictly speaking, the relationship between the upstream and the downstream is reversed in this case, but the case of the main flow is defined for convenience.
[0120]
The support plate 84a functions as a water guide plate that supports the inner cylinder 81 and guides the flow of water.
[0121]
With this configuration, the reverse flow from the outer peripheral side of the impeller 20 flows into the inner cylinder space 80, and the main flow and the reverse flow flowing through the center side of the flow path 36 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, struts 84b that connect the inner wall of the suction pipe 31 between the upstream side and the downstream side are formed in the slit 51a. Similarly, the inner cylinder 81a is formed so as to cover the slit 51a. That is, the inner cylinder and the support plate in the case of FIG. 13A are extended vertically downward and straddle the slit 51a.
[0123]
If comprised in this way, since the inner cylinder 81a has covered the slit 51a and the support plate 84b has also covered the slit 51a similarly, a swirl flow does not arise in the part of the slit 51a.
[0124]
In this example, the inner cylinder 81a may be further extended to the upstream side (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 opened in the vicinity of the connection portion of the inner cylinder 81a to the inner wall of the suction pipe 31. By comprising in this way, a swirl flow can be prevented more effectively.
[0125]
Next, a vertical shaft pump according to an eleventh embodiment of the present invention will be described with reference to a partial sectional view of FIG. This vertical shaft pump uses a so-called treatment. The treatment is also referred to as a casing treatment. When the pump is operated in a partial flow region, the reverse flow goes back from the outer periphery of the inlet of the impeller 20 to the suction pipe 31 side, but the reverse flow is prevented. Therefore, it is a return channel having a length in the axial direction that is attached to allow the backflow to pass through the casing at the inlet blade end portion of the impeller 20.
[0126]
In 11th Embodiment shown to Fig.14 (a), the part just before the entrance of the impeller 20 among the suction pipes 31 is expanded toward an outer peripheral part, and a treatment is formed. A 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 outer peripheral portion 31 e that the suction pipe 31 expands expands to the same diameter as the outer peripheral portion of the air chamber 50. The enlarged outer peripheral portion 31 e 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. As a result, the inner cylinder 31a and the inner wall of the air chamber 50 form a continuous inner wall. A hole 31b that communicates the annular space 31f and the inside of the suction pipe 31 is formed in the air chamber 50 connecting portion of the inner cylinder 31a. A plurality of holes 31b are formed and are equally arranged in the circumferential direction.
[0128]
In such a structure, when a reverse flow that flows out from the inlet tip of the impeller 20 to the suction side occurs, the reverse flow flows outward due to the swirl component. Therefore, the reverse flow flows into the space 31f and merges with the main flow at the center of the suction pipe 31 through the hole 31b. In this way, since the swirling flow in the slit 51a is suppressed, 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 opened in the circumferential direction. A plurality of stays 85b (preferably 2 or more and 16 or less) are provided for connecting and supporting the inner cylinder 31c corresponding to the inner cylinder 31a with the casing outer peripheral portion 31e. The stay 85b has a flat plate shape and is linearly formed in the axial direction. Therefore, it also has a function of a rectifying plate that rectifies the backflow flowing through the space 31f.
[0130]
In such a structure, when a backflow that flows out from the inlet tip of the impeller 20 to the suction side occurs, the swirl component of the backflow disappears or disappears while the backflow flows through the space 31f as in the example of FIG. Decrease.
[0131]
A strut 52b that connects the inner cylinder 31c and the inner wall of the suction pipe 31 may be formed across the slit 51a. That is, you may provide the support | pillar (The radial direction support | pillar, the inclination support | pillar, the support | pillar which protruded inside) as demonstrated in FIG.
[0132]
Next, a twelfth embodiment of the present invention will be described with reference to a partial sectional view of FIG. Since this embodiment is the same as the other embodiments except for the structure of the suction pipe 31, the illustration is omitted. As shown in the figure, an air pipe 40 that introduces air into the suction pipe 31 from one end is provided in the suction pipe 31 that constitutes the flow path 36 for flowing water toward the impeller 20.
[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, and the inner cylinder space 92 is opened on the downstream side (upward in the vertical direction) facing the impeller 20. Yes. The air inlet 40 to the suction pipe 31 by the air pipe 40 opens into the inner cylinder 91, and air is introduced into the suction pipe 31 through the air pipe 40 and the inlet 42 in accordance with a decrease in the pressure in the opening in the inner cylinder 91. It is configured to inhale.
[0134]
Here, a stay as a support member that connects the inner cylinder 91 and the inner wall of the suction pipe 31 is disposed in the inner cylinder space 92. The air pipe 40 may penetrate the inside of the stay 92a, or may penetrate the inner cylinder space 92 separately from the stay 92a.
[0135]
Further, as shown in FIG. 15B, the suction pipe 31 is formed in a bell mouth shape, and the upstream side of the inner cylinder 91 is extended to the lower end of the suction pipe 31 along the bell mouth. May be. If comprised in this way, at the time of backflow generation | occurrence | production, a backflow will flow out of the suction pipe 31, after eliminating the swirling component.
[0136]
Thus, since the backflow from the impeller 20 flows through the inner cylindrical space 92, a positive pressure is not generated in the vicinity of the intake port 42 or can be suppressed to a small positive pressure.
[0137]
【The invention's effect】
As described above, according to the present invention, inhalation of floating substances in water from the air pipe to the suction pipe is prevented, and the air pipe opening is not blocked by the floating substance, so that air is reliably sucked into the suction pipe. A vertical shaft pump can be provided.
[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 the relationship between each water level and a water level Lc that sucks air in a spiral shape from the lower end of the 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 cross-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 shaft pump according to a fifth embodiment of the present invention.
FIG. 8 is a cross-sectional view of a vertical shaft pump according to a sixth embodiment of the present invention.
FIG. 9 is a QH curve (performance curve) illustrating the characteristics of a vertical shaft pump.
FIG. 10 is a sectional view of a vertical shaft pump for explaining a seventh embodiment of the present invention.
FIG. 11 is a partial cross-sectional view of a vertical shaft pump according to an eighth embodiment of the present invention.
FIG. 12 is a partial cross-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 shaft pump according to an eleventh embodiment of the present invention.
FIG. 15 is a partial sectional view of a vertical shaft pump according to a twelfth embodiment of the present invention.
FIG. 16 is a front sectional view of a conventional vertical shaft pump.
[Explanation of symbols]
1 Aquarium
10 Vertical shaft pump
20 impeller
21 Rotating shaft
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 pipe
41 Air pipe opening
42 Inlet
43 Device for blocking floating substances
44 Strainer
45 Breeza
46 Air gap between breather and air pipe
47 Air tube roof enclosure
50 Air chamber
50a Air chamber wall
51a slit
52 slit
52a prop
70 Anti-rotation plate
80 Inner cylinder space
81 inner cylinder
82 Water flow path inside the inner cylinder
83 Hole for communicating the inner cylinder space with 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 cylinder stay
h Negative pressure head
HWL high water level
Ld Design water level (design water level for total discharge)
LWL Minimum water level
Lc Water level that draws air in a vortex
LO Water level that draws water into the suction pipe through the air pipe
SLWL Impeller suction start water level
A1 Inlet water level
A2 Lower level of suction pipe

Claims (13)

An impeller that rotates by a longitudinally arranged rotating shaft and sucks in water;
A suction pipe that is arranged upstream of the impeller and flows the water toward the impeller;
One end is connected to the suction pipe, the other end is lower than the highest water level of the sucked water, and below that even if the lower end of the suction pipe is lower than the water level of the sucked water An air pipe that opens at a position higher than the lowest water level that sucks air from the lower end of the suction pipe;
The opening direction of the air pipe is horizontal or downward from the horizontal ;
The suction pipe is configured to flow water along the inner wall toward the impeller;
The suction pipe has an inner cylinder that forms an annular inner cylinder space between the inner wall and the inner cylinder space, the downstream side of the inner cylinder space is opened to face the impeller, and the inner cylinder has an upstream side. Opening in the inner wall or at the lower end of the inner wall ;
An air inlet to the suction pipe by the air pipe opens into the inner cylinder, and air is sucked into the suction pipe through the air pipe and the air inlet in accordance with a decrease in pressure of the opening in the inner cylinder. Composed;
Vertical shaft pump. An impeller that rotates by a longitudinally arranged rotating shaft and sucks in water;
A suction pipe that is arranged upstream of the impeller and flows the water toward the impeller;
One end is connected to the suction pipe, the other end is lower than the highest water level of the sucked water, and below that even if the lower end of the suction pipe is lower than the water level of the sucked water An air pipe that opens at a position higher than the lowest water level that sucks air from the lower end of the suction pipe;
The opening direction of the air pipe is horizontal or downward from the horizontal ;
The suction pipe is configured to flow water along the inner wall toward the impeller;
The suction pipe has an inner cylinder that forms an annular inner cylinder space between the inner wall and the inner cylinder space. The inner cylinder space is opened downstream from the impeller so that the amount of water on the downstream side of the impeller Is configured to flow a reverse flow from the impeller when is less than the design point water volume ;
An air inlet to the suction pipe by the air pipe opens into the inner cylinder, and air is sucked into the suction pipe through the air pipe and the air inlet in accordance with a decrease in pressure of the opening in the inner cylinder. Composed;
Vertical shaft pump. An impeller that rotates by a longitudinally arranged rotating shaft and sucks in water;
A suction pipe that is arranged upstream of the impeller and flows the water toward the impeller;
One end is connected to the suction pipe, the other end is lower than the highest water level of the sucked water, and below that even if the lower end of the suction pipe is lower than the water level of the sucked water An air pipe that opens at a position higher than the lowest water level that sucks air from the lower end of the suction pipe;
The opening direction of the air pipe is horizontal or downward from the horizontal ;
The suction pipe is configured to flow water along the inner wall toward the impeller;
An air inlet is formed in the inner wall, the air pipe communicates with the inside of the suction pipe through the air inlet, and air is introduced into the suction pipe through the air pipe and the air inlet in accordance with 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 with the inner wall between the impeller and the intake port, and an upstream side of the inner cylinder is in the vicinity of the intake port. The inner cylinder is connected to the inner wall, the inner cylinder forms a tapered nozzle whose flow path area decreases along the flow of water, the inner cylinder space is opened facing the impeller on the downstream side, In the vicinity of the connection portion of the inner cylinder with the inner wall, a hole is formed to communicate the inner cylinder space and the water flow path inside the inner cylinder;
Vertical shaft pump. An impeller that rotates by a longitudinally arranged rotating shaft and sucks in water;
A suction pipe that is arranged upstream of the impeller and flows the water toward the impeller;
One end is connected to the suction pipe, the other end is lower than the highest water level of the sucked water, and below that even if the lower end of the suction pipe is lower than the water level of the sucked water An air pipe that opens at a position higher than the lowest water level that sucks air from the lower end of the suction pipe;
The opening direction of the air pipe is horizontal or downward from the horizontal ;
The suction pipe is configured to flow water toward the impeller along an inner wall, and has an annular air chamber surrounding the inner wall;
One end of the air tube is connected to the air chamber;
A slit-like air inlet is formed in the inner wall, and the air chamber communicates with the inside of the suction pipe through the air inlet, and the inside of the suction pipe passes through the air pipe and the air inlet in response to a decrease in pressure in the suction pipe. Configured to inhale air;
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 space includes the inner cylinder and the inner wall. A support plate for connecting the inner cylinder space, the inner cylinder space is opened to the flow path in the vicinity of the intake port on the upstream side, and opened to face the impeller on the downstream side;
Vertical shaft pump. An impeller that rotates by a longitudinally arranged rotating shaft and sucks in water;
A suction pipe that is arranged upstream of the impeller and flows the water toward the impeller;
One end is connected to the suction pipe, the other end is lower than the highest water level of the sucked water, and below that even if the lower end of the suction pipe is lower than the water level of the sucked water An air pipe that opens at a position higher than the lowest water level that sucks air from the lower end of the suction pipe;
The opening direction of the air pipe is horizontal or downward from the horizontal ;
The suction pipe is configured to flow water toward the impeller along an inner wall, and has an annular air chamber surrounding the inner wall;
One end of the air tube is connected to the air chamber;
The inner wall is formed with a slit-like inlet that communicates the annular air chamber and the suction pipe over the entire circumference of the suction pipe, and the air pipe and the inlet according to a decrease in pressure in the suction pipe Configured to suck air into the suction pipe through;
A casing treatment is formed between the air inlet and the impeller;
The casing treatment includes an inner wall and an outer casing disposed outside the inner wall, and one of the spaces between the inner wall and the outer casing opens at an inlet blade end portion of the impeller. And the other constitutes a return channel having a length in the axial direction, opened in the vicinity of the inlet;
Vertical shaft pump. The vertical shaft pump according to any one of claims 1 to 5 , wherein the other end of the air pipe is formed in an inverted U shape and the opening direction is downward. An impeller that rotates by a longitudinally arranged rotating shaft and sucks in water;
A suction pipe that is arranged upstream of the impeller and flows the water toward the impeller;
One end is connected to the suction pipe, the other end is lower than the highest water level of the sucked water, and below that even if the lower end of the suction pipe is lower than the water level of the sucked water An air pipe that opens at a position higher than the lowest water level that sucks air from the lower end of the suction pipe;
E Bei a device to cut off the suspended matter to the other end of the air tube;
The suction pipe is configured to flow water along the inner wall toward the impeller;
The suction pipe has an inner cylinder that forms an annular inner cylinder space between the inner wall and the inner cylinder space, the downstream side of the inner cylinder space is opened to face the impeller, and the inner cylinder has an upstream side. Opening in the inner wall or at the lower end of the inner wall ;
An air inlet to the suction pipe by the air pipe opens into the inner cylinder, and air is sucked into the suction pipe through the air pipe and the air inlet in accordance with a decrease in pressure of the opening in the inner cylinder. Composed;
Vertical shaft pump. An impeller that rotates by a longitudinally arranged rotating shaft and sucks in water;
A suction pipe that is arranged upstream of the impeller and flows the water toward the impeller;
One end is connected to the suction pipe, the other end is lower than the highest water level of the sucked water, and below that even if the lower end of the suction pipe is lower than the water level of the sucked water An air pipe that opens at a position higher than the lowest water level that sucks air from the lower end of the suction pipe;
E Bei a device to cut off the suspended matter to the other end of the air tube;
The suction pipe is configured to flow water along the inner wall toward the impeller;
The suction pipe has an inner cylinder that forms an annular inner cylinder space between the inner wall and the inner cylinder space. The inner cylinder space is opened downstream from the impeller so that the amount of water on the downstream side of the impeller Is configured to flow a reverse flow from the impeller when is less than the design point water volume ;
An air inlet to the suction pipe by the air pipe opens into the inner cylinder, and air is sucked into the suction pipe through the air pipe and the air inlet in accordance with a decrease in pressure of the opening in the inner cylinder. Composed;
Vertical shaft pump. An impeller that rotates by a longitudinally arranged rotating shaft and sucks in water;
A suction pipe that is arranged upstream of the impeller and flows the water toward the impeller;
One end is connected to the suction pipe, the other end is lower than the highest water level of the sucked water, and below that even if the lower end of the suction pipe is lower than the water level of the sucked water An air pipe that opens at a position higher than the lowest water level that sucks air from the lower end of the suction pipe;
E Bei a device to cut off the suspended matter to the other end of the air tube;
The suction pipe is configured to flow water along the inner wall toward the impeller;
An air inlet is formed in the inner wall, the air pipe communicates with the inside of the suction pipe through the air inlet, and air is introduced into the suction pipe through the air pipe and the air inlet in accordance with 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 with the inner wall between the impeller and the intake port, and an upstream side of the inner cylinder is in the vicinity of the intake port. The inner cylinder is connected to the inner wall, the inner cylinder forms a tapered nozzle whose flow path area decreases along the flow of water, the inner cylinder space is opened facing the impeller on the downstream side, In the vicinity of the connection portion of the inner cylinder with the inner wall, a hole is formed to communicate the inner cylinder space and the water flow path inside the inner cylinder;
Vertical shaft pump. An impeller that rotates by a longitudinally arranged rotating shaft and sucks in water;
A suction pipe that is arranged upstream of the impeller and flows the water toward the impeller;
One end is connected to the suction pipe, the other end is lower than the highest water level of the sucked water, and below that even if the lower end of the suction pipe is lower than the water level of the sucked water An air pipe that opens at a position higher than the lowest water level that sucks air from the lower end of the suction pipe;
E Bei a device to cut off the suspended matter to the other end of the air tube;
The suction pipe is configured to flow water toward the impeller along an inner wall, and has an annular air chamber surrounding the inner wall;
One end of the air tube is connected to the air chamber;
A slit-like air inlet is formed in the inner wall, and the air chamber communicates with the inside of the suction pipe through the air inlet, and the inside of the suction pipe passes through the air pipe and the air inlet in response to a decrease in pressure in the suction pipe. Configured to inhale air;
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 space includes the inner cylinder and the inner wall. A support plate for connecting the inner cylinder space, the inner cylinder space is opened to the flow path in the vicinity of the intake port on the upstream side, and opened to face the impeller on the downstream side;
Vertical shaft pump. An impeller that rotates by a longitudinally arranged rotating shaft and sucks in water;
A suction pipe that is arranged upstream of the impeller and flows the water toward the impeller;
One end is connected to the suction pipe, the other end is lower than the highest water level of the sucked water, and below that even if the lower end of the suction pipe is lower than the water level of the sucked water An air pipe that opens at a position higher than the lowest water level that sucks air from the lower end of the suction pipe;
E Bei a device to cut off the suspended matter to the other end of the air tube;
The suction pipe is configured to flow water toward the impeller along an inner wall, and has an annular air chamber surrounding the inner wall;
One end of the air tube is connected to the air chamber;
The inner wall is formed with a slit-like inlet that communicates the annular air chamber and the suction pipe over the entire circumference of the suction pipe, and the air pipe and the inlet according to a decrease in pressure in the suction pipe Configured to suck air into the suction pipe through;
A casing treatment is formed between the air inlet and the impeller;
The casing treatment includes an inner wall and an outer casing disposed outside the inner wall, and one of the spaces between the inner wall and the outer casing opens at an inlet blade end portion of the impeller. And the other constitutes a return channel having a length in the axial direction, opened in the vicinity of the inlet;
Vertical shaft pump. The device for blocking the suspended matter is a strainer;
The vertical shaft pump according to any one of claims 7 to 11 . A device for blocking the suspended matter is a breather;
The vertical shaft pump according to any one of claims 7 to 11 .

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