JP4422438B2 - 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. 11, 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 operating water level LWL of the suction water tank 1. There was a vertical pump 3 that allowed it to continue. In this pump 3, a through hole 5 is provided in the suction pipe 4 on the inlet side of the impeller 2, and an air pipe 6 opened to the outside air is attached to the through hole 5 so as to pass through at a level below the lowest operating water level LWL lower than the highest water level HWL. The amount of air flowing in through the holes 5 is changed according to the water level to gradually reduce the amount of drainage. The through hole 5 is h≈v from the water level LWL.²A position LLWL which is lower by 2 g is opened. v is the flow velocity of water in that portion, and g is the acceleration of gravity.
[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. 3-56895 (FIG. 1, FIG. 2, FIG. 3, FIG. 5)
[0005]
[Problems to be solved by the invention]
In the conventional pump as described above, there is no problem when the discharge flow rate of the pump is near the design point. However, on the small water volume side from the design point, there is a backflow from the discharge side to the suction side on the outer peripheral side of the impeller 2. Arise. Therefore, in addition to the axial flow, a swirling flow around the axis is generated in the suction pipe 4, and this swirling flow generates a positive pressure near the inner surface of the suction pipe 4. Even if this positive pressure cancels out the negative pressure due to the flow velocity v of the pumped water, and the water level in the tank drops from the high water level and falls below the minimum operating water level LWL, air flows through the through hole 5 as expected. There was a problem that the transition of operation could not be performed smoothly due to lack of air flow or too little air flowing in.
[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 preliminary standby operation, in which air surely flows into a suction pipe disposed on the upstream side of an impeller.
[0007]
[Means for Solving the Problems]
  In order to achieve the above object, the claims7As 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 and sucks water in the water tank 1; and on the upstream side of the impeller 20. A suction pipe 31 disposed and formed by a casing wall, the suction pipe 31 having an annular air chamber 50 surrounding the inner surface of the casing wall; one end connected to the air chamber 50 and the other end in the water tank 1 And an air pipe 60 that opens above the highest water level HWL; an air inlet 51a is formed on the inner surface of the casing wall, and the air chamber 50 communicates with the inside of the air inlet pipe 31 by the air inlet 51a. The water on the inner surface of the casing wall between the impeller 20 and the intake port 51a is prevented from rotating due to the rotation of the impeller 20;FlatAnti-rotation plate 70Toward the radial direction and the axial direction of the suction pipe 31Is formed.
[0008]
If comprised in this way, since the cyclic | annular air chamber 50 is provided, air can be uniformly distributed, and since a rotation prevention board is provided, a swirl flow can be prevented.
[0009]
  And claims7In the vertical shaft pump described in 1), the intake port is formed in a slit shape 51 a along the annular air chamber 50. The intake port is typically formed in a slit shape as described above, but may be a hole 51b (see, for example, FIG. 2), and more specifically, a plurality of holes opened along an annular air chamber. May be.
[0010]
MaFor example, as shown in FIG.7In the vertical shaft pump described above, a support column 52 that connects the inner surface of the casing wall between the upstream side and the downstream side of the intake port 52 across the intake port 52.c,52d is formedRu.
[0011]
  MaTheFor example, FIG.d) To (e),7In the vertical shaft pump described in FIG.c,52dLet the tip protrude into the air chamber 50An air guide plate that guides air flowing from the air chamber 50 into the suction pipe 31 is formed.The
[0012]
  With this configuration, since the struts are formed, in addition to reinforcing the casing wall, the strutsSince the tip is projected into the air chamber, it constitutes an air guide plate that guides the air flowing from the air chamber into the suction pipe.It is also possible to guide the air so that it is easily sucked into the water.
[0013]
  In order to achieve the object, the claims8For example, as shown in FIG. 4, the vertical shaft pump according to the invention is rotated by a rotary shaft 21 arranged in the vertical direction, and is arranged on the upstream side of the impeller 20; A suction pipe 31 formed by a casing wall, the suction pipe 31 having an annular air chamber 50 surrounding the inner surface of the casing wall; one end connected to the air chamber 50 and the other end in the water tank 1 An air pipe 60 that opens above the highest water level HWL; a slit-like air inlet 52 that communicates the annular air chamber 50 and the suction pipe 31 is formed on the inner surface of the casing wall; 52Let the tip protrude into the air chamber 50An air guide plate 52 that guides the air flowing from the air chamber 50 toward the suction pipe 31.c,52d is arranged. At this time, the turning prevention plate 70 may not be provided.
[0014]
If comprised in this way, since an annular air chamber and the air guide plate of a slit are provided, in addition to the air flow becoming uniform, there exists an effect of attracting air in water by the shape of a guide plate.
[0015]
MaFor example, as shown in FIGS.7 andClaim8In the vertical shaft pump described in 1), the air guide plates 52c and 52d are inclined in the rotational direction of the impeller 20 with respect to the radial direction around the rotational shaft 21.
[0016]
  In order to achieve the object, the claims1As shown in FIG. 5, for example, the vertical shaft pump according to the invention is rotated by a rotary shaft 21 arranged in the vertical direction and sucks water in the water tank 1; A suction pipe 31 formed by a casing wall; an intake port 51b is formed on the inner surface of the casing wall, one end is connected to the intake port 51b, and the other end is above the highest water level HWL in the water tank 1. The suction pipe 31 has an inner cylinder 81 that forms an annular inner cylinder space 81a between the inner surface of the casing wall and the impeller 20 and the intake port 51b. The upstream side of the inner cylinder 81 is connected to the inner surface of the casing wall in the vicinity of the intake port 51b, and the inner cylinder 81 forms a tapered nozzle whose flow area decreases along the flow of water. 81a is opposite to the impeller 20 on the downstream side. It was opened by a hole 82 for communicating the inner cylinder space 81a and the flow path 36 in the vicinity of the connection portion between the inner surface of the casing wall of the inner cylinder 81 is formed.
[0017]
With this configuration, the suction pipe has an inner cylinder that forms an annular inner cylinder space between the inner surface of the casing wall between the impeller and the intake port, and the upstream side of the inner cylinder is the intake side. Connected to the inner wall in the vicinity of the mouth, the inner cylinder forms a tapered nozzle whose flow path area decreases along the flow of water, and the inner cylinder space is opened facing the impeller downstream. Therefore, the backflow from the impeller flows into the inner cylinder space, and a hole that connects the inner cylinder space and the flow path is formed in the vicinity of the connection portion between the inner cylinder and the inner surface of the casing wall. The reverse flow flows out of the hole. In this way, the swirl flow due to the reverse flow is suppressed.
[0018]
  And claims2As claimed in1In addition, as shown in FIG. 6, for example, the suction pipe 31 includes an annular air chamber 50 that surrounds the inner surface of the casing wall and is connected to one end of the air pipe 60. You may form in slit shape along the air chamber 50 so that the air chamber 50 and the suction pipe 31 may be connected.
[0019]
  In order to achieve the object, the claims3The vertical shaft pump according to the invention according to the invention, for example, as shown in FIG. 7, is rotated by a rotary shaft 21 arranged in the vertical direction and sucks water in the water tank 1; A suction pipe 31 formed by a casing wall, the suction pipe 31 having an annular air chamber 50 surrounding the inner surface of the casing wall; one end connected to the air chamber 50 and the other end in the water tank 1 An air pipe 60 that opens above the highest water level HWL; and an inner surface of the casing wall is formed with a slit-like intake port 51a that communicates the annular air chamber 50 and the suction pipe 31; 31 has an inner cylinder 83 that forms an annular inner cylinder space 84 between the impeller 20 and the intake port 51a and the inner surface of the casing wall. Connected to the inner surface of the casing wall That the supporting plate 84a is arranged, the inner cylinder space 84 is open to the flow passage 36 at the inlet 51a near the upstream side, is open to face the impeller 20 on the downstream side.
[0020]
The support plate 84a may function as a water guide plate that supports the inner cylinder 83 and guides the flow of water.
[0021]
If comprised in this way, since it has an inner cylinder which forms a cyclic | annular inner cylinder space between the inner surfaces of a casing wall, the backflow from an impeller flows through an inner cylinder space. Moreover, since the support plate which connects an inner cylinder and the inner surface of the said casing wall is arrange | positioned in the inner cylinder space, an inner cylinder can be supported by a casing 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.
[0022]
  And claims4As shown in FIG. 7 (see FIG. 7 for example), the intake port 51a may be formed with a support column 52b that connects the inner surface of the casing wall between the upstream side and the downstream side across the intake port 51a.
[0023]
  In order to achieve the object, the claims9As shown in FIG. 8, for example, the vertical shaft pump according to the invention is rotated by a rotary shaft 21 arranged in the vertical direction, and is disposed on the upstream side of the impeller 20; A suction pipe 31 formed by a casing wall, the suction pipe 31 having an annular air chamber 50 surrounding the inner surface of the casing wall; one end connected to the air chamber 50 and the other end in the water tank 1 An air pipe 60 that opens above the highest water level HWL; and a slit-like air inlet 51 a that communicates the annular air chamber 50 and the suction pipe 31 on the inner surface of the casing wall over the entire circumference of the suction pipe 31. A casing treatment 85 is formed between the air inlet 51a and the impeller 20; the casing treatment 85 is formed of a casing wall of the suction pipe and a casing of the suction pipe. Is configured to include an outer casing 31e disposed outside the grayed wall, the space 31f between the casing wall and the outer casing 31e of the suction tube, one opens the inlet blade tip portion of the impeller 20MouthThe other opened near the inlet 51aIt is a return flow path, and the water flowing in from the opening at the inlet blade end is returned to the main flow at the center of the suction pipe 31 from the opening near the intake port 51a.A return channel having a length in the axial direction is formed.
[0024]
  And claims10Claims as described in9In the vertical shaft pump described in (5), for example (see FIG. 8B), the intake port 51a is formed with a support column 52b that connects the casing wall of the suction pipe between the upstream side and the downstream side across the intake port 51a. Also good.
[0025]
In order to achieve the object, the claims5For example, as shown in FIG. 9, the vertical shaft pump according to the invention is rotated by a rotary shaft 21 arranged in the vertical direction, and is arranged on the upstream side of the impeller 20; A suction pipe 31 formed by a casing wall; and the suction pipe 31 has an inner cylinder 91 that forms an annular inner cylinder space 92 between the inner surface of the casing wall.AndAn air pipe 60 that introduces air into the suction pipe 31 from one end, and the other end of the air pipe 60 opens above the highest water level HWL in the water tank 1.furtherProvided; the inner cylinder space 92 is opened downstream from the impeller 20; the air inlet to the suction pipe 31 by the air pipe 60 opens into the inner cylinder 91.Ru.
[0026]
Typically, a support member 92 a that connects the inner cylinder 91 and the inner surface of the casing wall is disposed in the inner cylinder space 92. The air pipe 60 may penetrate the inside of the support member 92a, or may penetrate the inner cylindrical space 92 separately from the support member 92a.
[0027]
  And claims6As described above, the suction pipe 31 is formed in a bell mouth shape, and the upstream side of the inner cylinder 93 may be extended along the bell mouth (see, for example, FIG. 9B).
[0028]
  Also,For example, as shown in FIG. 10, the vertical shaft is rotated by a rotary shaft arranged in the vertical direction, and is disposed on the upstream side of the impeller 20; A suction pipe 31 formed by a casing wall, the suction pipe 31 having an annular air chamber 50 surrounding the inner surface of the casing wall; one end connected to the air chamber 50 and the other end in the water tank An air pipe 60 that opens above the highest water level HWL; and an inner surface of the casing wall is formed with a slit-like air inlet 51a that connects the annular air chamber 50 and the suction pipe 31; An air guide plate 71 that guides air flowing from the air pipe 60 into the air chamber 50 is disposed in the chamber 50.May.
[0029]
If comprised in this way, since the air guide plate which guides the air which flows in into an air chamber from an air pipe is arrange | positioned in an air chamber, it has the effect of guiding the air in an air chamber to a suction pipe and attracting air to water. .
[0030]
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.
[0031]
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 shown in (a) is a pump for preceding standby operation.
[0032]
Pre-standby operation, especially full-speed pre-standby operation, starts the pump in advance before rainwater flows into the pump tank, starts draining as the water level (Level) L rises, and stops the pump even if the water level drops. Without driving at full speed. 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.
[0033]
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.
[0034]
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.
[0035]
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).
[0036]
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.
[0037]
An air chamber 50 that is an annular cavity that surrounds the casing around the axis of the rotating shaft 20 (or a coaxial extension) is formed outside the casing, which is located below the tip of the impeller 20. In the present embodiment, the air chamber 50 is formed in the upper portion of the suction pipe 31 and in the vertical cylindrical portion. It is located immediately below the casing liner 32 and immediately below the tip of the impeller 20. The air chamber 50 surrounds the inner surface of the casing wall that forms the suction pipe 31 and is formed outside the inner surface.
[0038]
The suction side portion of the casing (suction pipe 31 in the present embodiment), specifically, an air inlet that connects the air chamber 50 and the inside of the suction pipe 31 to the inner surface of the casing wall that forms the suction pipe 31 As a result, an intake slit 51a is formed. The position of the slit 51a is lower than the tip (suction end) of the impeller 20. Instead of the slits, a large number of suction holes 51b may be used as in the example of FIG. 2 described later (in this example, the air chamber 50 is unnecessary).
[0039]
The air chamber 50 is a space surrounded by an air chamber wall 50a. In the present embodiment, the air chamber wall 50 a has a casting structure integrated with the main body portion of the suction pipe 31. One end of an air pipe 60 is connected to the outside of the air chamber wall 50a. The number of the air pipes 60 may be one as illustrated, but may be plural, for example, four.
[0040]
Providing the air chamber 50 is convenient because the air sucked from the air pipe 60 is uniformly distributed over the entire circumference of the suction pipe 31. In particular, when the cross-sectional area of the air chamber 50 can be sufficiently large so that the flow resistance of air flowing in the circumferential direction of the annular air chamber 50 can be ignored, the number of the air pipes 60 may be one.
[0041]
On the other hand, when a plurality of air pipes 60 are provided, the cross-sectional area of the air chamber 50 can be made relatively small. For example, it may be four.
[0042]
The relationship between the air chamber 50, the slit 51a, and the connection portion of the air pipe 60 will be described with reference to an enlarged view of the same portion. The upper end portion of the slit 51a is formed at a position lower than the upper end of the air pipe connection portion. Therefore, as described later, the water level for sucking air is determined with reference to the upper end of the slit 51a.
[0043]
The other end (upper end) 61 of the air pipe 60 is opened above the highest water level HWL in the water tank 1. The highest water level HWL may be called the water level at which the water level can rise most in the water tank 1, that is, the allowable water level of the water tank 1. Therefore, the other end 61 of the air pipe 60 is not submerged in water.
[0044]
The impeller 20 is arrange | positioned below the below-mentioned minimum water level LWL. The entire main body portion 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.
[0045]
On the inner surface of the casing (here, the suction pipe 31) between the impeller 20 and the slit 51a, a flat anti-rotation plate 70 is formed in the radial direction and in the axial direction (vertical direction). The anti-rotation plate 70 is preferably an integral structure when the suction pipe 31 is made of a casting. A plurality of anti-rotation plates 70 are provided. For example, the number is four. The lower end of the rotation preventing plate 70 and the slit 51a are spaced apart from each other by a certain amount. However, they may be close.
[0046]
Next, the relationship between the structure in the height direction of the pump 10 and the water level will be described. 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 if the air pipe 60 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 60 enables operation at a low water level. However, the water level LWL may be determined under conditions other than the spiral air suction.
[0047]
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 60 is closed and the water level is lowered with an actual machine, the operation is possible even if it is slightly below the design-designated minimum water level Ld.
[0048]
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.
[0049]
Below the suction start water level SLWL, there is an intake water level A1 corresponding to the height of the slit 51a. This corresponds to the upper end of the slit 51a. When the water level L decreases and reaches the water level LWL, the water level in the air pipe 60 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 60. .
[0050]
In the present embodiment, since the upper end of the slit 51a is formed lower than the height of the upper end of the connection portion of the air chamber wall 50a of the air pipe 60, the height of the upper end of the slit 51a is the intake port. The water level is A1. Conversely, when the upper end of the slit 51a is higher than the height of the upper end of the connection portion of the air chamber wall 50a of the air tube 60, the height of the upper end of the connection portion of the air chamber wall 50a of the air tube 60 is the intake air. It becomes the mouth water level A1.
Below the intake water level A1, there is a water level A2 at the tip of the suction pipe 31.
[0051]
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 there is rainfall information indicating that heavy rain has fallen upstream of the river, it is predicted that the water level 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 is lower than A2. This is the start of the preceding standby operation.
[0052]
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 exceeds the water level A1, water is not yet sucked up. The impeller 20 is idling.
[0053]
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 together with water into the suction pipe 31 through the air pipe 60 and through the air chamber 50 from the slit 51a, so the pump is not the operation of 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.
[0054]
Furthermore, the water level rises to a water level between the water level LWL 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 air starts to be sucked through the air pipe 60 at the water level LWL (because the water level in the air pipe 60 reaches the intake water level A1). 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 idling 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.
[0055]
The airlock water level is designed so as to coincide with or be close to the water level A1, which is normally the height of the intake port, but it does not necessarily coincide. When the water level further passes through A1 or reaches the lower end water level A2 of the suction bell, the water amount may become zero. 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.
[0056]
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.
[0057]
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.
[0058]
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.
[0059]
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.
[0060]
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 clarified with reference to a partial sectional view of FIG. In this figure, the case where an inlet port is not the slit 51a but the suction hole 51b is shown. The principle is the same whether it is the slit 51a or the suction hole 51b.
[0061]
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. That is, by design, a slit 51a and a suction hole 51b are provided at this position. 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.
[0062]
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.
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 part area of the 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. Hl is a flow loss from the lower end A2 of the suction pipe 31 to the intake port 51b. 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 51b 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 water level Ld is the water level calculated as described above. When the water level L is increasing, the air is not sucked from the suction holes 51b, and the pump is discharged in total. When the water level L is decreasing, Here, the water level is such that the discharge of the entire amount ends and the suction of air from the suction hole 51b starts.
[0065]
By design, the water level Ld provides a margin against the water level in which air is sucked in spirally 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]
The water level Lc is a check item in determining 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]
Furthermore, with reference to FIG. 2, the effect | action of the rotation prevention board 70 is demonstrated.
The water level Ld 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 suction hole 51a. 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. As will be described later, the swirl flow occurs when the pump discharge amount is smaller than the point flow rate.
[0069]
Considering the positive pressure hp, h is as follows.
h = hl + (v²/ 2g) -hp
[0070]
When the positive pressure hp is generated, air is not sucked from the air pipe 60 even if the water level L drops to the water level Ld. Therefore, the air-water mixing operation is not performed as expected, and if it is poor, air may be sucked in from the lower end of the suction pipe 31 to cause vibrations and the like.
[0071]
According to the present embodiment, the swirl prevention plate 70 prevents swirling flow in the suction pipe 31, so that air can be sucked in when the hp is substantially zero or sufficiently small and the water level L becomes Ld. It becomes. Alternatively, air can be sucked in where the water level L is not much lower than Ld.
[0072]
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 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.
[0073]
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.
[0074]
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. Although FIG. 1 shows a case where the height difference between A1 and HWL is not so large, in practice, 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.
[0075]
Point A in the figure indicates the operating point (essential point) when there is no air inflow in the planned actual head. At this time, the pumped water in the suction pipe 31 is directed uniformly toward the impeller 20 in the axial direction. It is flowing. 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 near the inner wall of the suction pipe 31 in the pumping water that is swung in the rotational direction of the impeller 20. .
[0076]
The anti-swivel plate 70 described above prevents such a swirling flow, and thus has an effect of reducing the positive pressure hp.
[0077]
Returning to FIG. 1, the structure and operation of the air chamber 50 will be described with reference to an enlarged view (b) of the air chamber 50.
In the enlarged view (b), the upper end of the slit 51a is formed lower by ha than the opening of the air pipe 60 to the air chamber wall 50a. Therefore, even if the water level L becomes close to the lowest water level Ld and the water level in the air pipe 60 is lowered to the opening of the air pipe 60 to the air chamber wall 50a, air is not yet sucked into the suction pipe 31. The water level L further decreases, the water level in the air pipe 60 further decreases by ha, and air suction starts when it reaches the upper end of the slit 51a.
[0078]
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 60, 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 60 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.
[0079]
As shown in FIG. 1 (c), if the upper end of the slit 51a is not a straight line when viewed from the front, but a wave shape, or a shape having a periodic vertical change, such as providing a periodic cutout, Since air flows uniformly from the high part into the suction pipe 31 over the entire circumference in the form of small bubbles, air suction into the impeller 20 can be made uniform.
[0080]
A second embodiment of the present invention will be described with reference to FIG. (A) is a fragmentary sectional view which extracts and shows only the air chamber 50 periphery. (B), (c), (d), and (e) are views taken along the line XX when the suction pipe is viewed at a position of the slit 52.
[0081]
In the present embodiment, a slit 52 as an air inlet, which is similar to the slit 51a of the first 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.
[0082]
The slit 52 is formed with struts 52 a that straddle the slit 52 and connect the inner wall of the suction pipe 31, that is, the inner surface of the casing wall, on the upstream side and the downstream side.
[0083]
As shown in (b), 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.
[0084]
Moreover, as shown in (c), the support column may constitute an air guide plate 52 b that guides 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.
[0085]
Further, as shown in (d), the air guide plate 52c may be inclined in the direction of swirling of water with respect to the radial direction. If comprised in this way, there exists an effect which attracts the inhaled air to rotation of water, and it makes it easy to inhale air although there exists a swirling flow.
[0086]
Further, as shown in (e), the air guide plate 52d is inclined in the direction of swirling of the water with respect to the radial direction, and the tip of the air guide plate 52d is placed on the inner surface of the casing (the suction pipe 31 in the present embodiment). You may make it protrude rather. 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.
[0087]
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.
[0088]
In FIG. 4, the second embodiment has been described as including the anti-rotation plate 70 in addition to the slit with the support column. However, the anti-rotation plate 70 may be omitted in view of the air attraction effect of the slit with the support column. Good. In particular, in the case of the modification described in (d) and (e), the rotation preventing plate 70 can be omitted.
[0089]
In the second 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.
[0090]
In the first and second embodiments, the backflow prevention plate 70 has a linear shape in the axial direction, but its radial height is 0.1 of the inner diameter of the suction pipe 31 at the mounting position of the backflow prevention plate 70. It is preferable to make it not more than twice. 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.
[0091]
The third embodiment will be described with reference to FIG. In the present embodiment, the suction pipe 31 has an inner cylinder 81 that forms an annular inner cylinder space 81a between the inner surface of the casing wall between the impeller 20 and the air hole 51b as an intake port. is doing. The inner cylinder 81 is connected to the inner surface of the casing wall in the vicinity of the air hole 51b on the upstream side, that is, in the vertical direction, and the inner cylinder 81 forms a tapered nozzle whose flow area decreases along the flow of water. ing. 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 surface of the casing wall of the suction pipe 31, a hole 82 that connects the inner cylinder space 81 a and the flow path 36 is formed.
[0092]
With this configuration, the flow that flows backward on the outer peripheral side of the impeller 20 in a 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 82 to draw the suction pipe 31. The swirl flow disappears or weakens before it flows into Therefore, the positive pressure hp does not occur in the air hole 51b portion, or even if it occurs, it becomes a small value.
[0093]
A modification of the third embodiment will be described with reference to FIG. A slit 51a is formed instead of the air hole 51b in the case of FIG. That is, the suction pipe 31 has an annular (annular in this embodiment) air chamber 50 that surrounds the inner surface of the casing wall and is connected to one end of the air pipe 60, and communicates the air chamber 50 with the suction pipe 31. Along the air chamber 50, the air inlet is formed in a slit shape. The width of the slit 51a is preferably 0.005 to 0.05 Da.
[0094]
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 82 of the inner cylinder 81.
[0095]
In the third embodiment, a plate-like stay (not shown) may be provided between the inner cylinder 81 forming the nozzle and the inner surface of the casing 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 may have a thickness of 0.01 to 0.1 Da.
[0096]
In the third embodiment, the diameter of the narrowest portion of the tapered nozzle is preferably 0.7 to 0.9 Da. The axial length from the lower end of the slit 51a or the hole 82 to the narrowest part of the tapered nozzle is preferably 0.1 to 0.3 Da.
[0097]
The fourth embodiment will be described with reference to FIG. In this figure, the suction pipe 31 and the air pipe 60 are extracted and shown.
[0098]
As shown to (a), the slit 51a as an inlet which connects the annular air chamber 50 and the suction pipe 31 is formed in the inner surface of the casing wall of the suction pipe 31, and the pressure in the suction pipe 31 is reduced. In response to the decrease, air is sucked into the suction pipe 31 through the air pipe 60 and the slit 51a.
[0099]
The suction pipe 31 has an inner cylinder 83 between the impeller 20 and the slit 51a. The inner cylinder 83 forms an annular inner cylinder space 84 between the inner surface of the casing wall of the suction pipe 31. A support plate 84 a that connects the inner cylinder 83 and the inner surface of the suction pipe 31 is disposed in the inner cylinder space 84. The inner cylindrical space 84 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 cylindrical space 84 may flow backward, strictly speaking, the relationship between the upstream and the downstream is reversed at that time, but it is defined in the case of the main flow for convenience.
[0100]
The support plate 84a functions as a water guide plate that supports the inner cylinder 83 and guides the flow of water.
[0101]
With this configuration, the backflow from the outer peripheral side of the impeller 20 flows into the inner cylinder space 84, and the main flow and the backflow flowing through the center side of the flow path 36 are separated by the inner cylinder 83. Therefore, the swirling flow in the suction pipe 31 is prevented. It is also possible to suppress the swirling flow by guiding the support plate 84a.
[0102]
A modification of the fourth embodiment will be described with reference to (b). 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 83a is formed so as to cover the slit 51a. That is, in the case of (a), the inner cylinder and the support plate are extended vertically downward and straddle the slit 51a.
[0103]
If comprised in this way, since the inner cylinder 83a 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.
[0104]
In this example, the inner cylinder 83a may be further extended to the upstream side (downward in the vertical direction), expanded in a bell mouth shape, and connected to the inner surface of the suction pipe 31. At this time, a hole is made in the vicinity of the connection portion to the inner surface of the suction pipe 31 of the inner cylinder 83a. By comprising in this way, a swirl flow can be prevented more effectively.
[0105]
A vertical shaft pump according to a fourth embodiment will be described with reference to a partial cross-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.
[0106]
In the fifth embodiment shown in the partial sectional view of (a), a treatment is formed by enlarging the outer peripheral portion of the suction pipe 31 immediately before the entrance of the impeller 20 toward the outside. A portion of the suction pipe 31 immediately before the entrance of the impeller 20 has a casing wall parallel to the axial direction. At the same diameter position as the casing wall of the suction pipe, the suction pipe casing wall 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 first embodiment. The space 31f and the air chamber 50 are separated by an air chamber upper wall 50b.
[0107]
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 casing 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 opened and are equally arranged in the circumferential direction.
[0108]
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.
[0109]
A modification of the fifth embodiment will be described with reference to a partial sectional view of (b). In this example, the plurality of holes 31b in the case of (a) 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.
[0110]
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 decreases while the backflow flows in the space 31f as in the example of (a). .
[0111]
A strut 52b that connects the inner cylinder 31c and the casing wall of the suction pipe 31 may be formed across the slit 51a. That is, you may provide the support | pillar (a radial direction support | pillar, an inclination support | pillar, the support | pillar which protruded inside) as demonstrated in FIG.
[0112]
The sixth embodiment will be described with reference to the partial cross-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 60 that introduces air into the suction pipe 31 from one end is provided in the suction pipe 31 that constitutes the flow path 36 that flows water toward the impeller 20. Similar to the other embodiments, the other end of the air pipe 60 is opened above the highest water level HWL of the water tank 1.
[0113]
The suction pipe 31 has an inner cylinder 91 that forms an annular inner cylinder space 92 between the inner surface of the casing wall, and the inner cylinder space 92 faces the impeller 20 on the downstream side (vertically upward). It is open. An air inlet 62 to the suction pipe 31 by the air pipe 60 opens into the inner cylinder 91, and enters the suction pipe 31 through the air pipe 60 and the air inlet 62 in accordance with a decrease in pressure at the opening in the inner cylinder 91. It is configured to inhale air.
[0114]
Here, a stay 92 a as a support member that connects the inner cylinder 91 and the inner surface of the casing wall of the suction pipe 31 is disposed in the inner cylinder space 92. The air pipe 60 may penetrate the inside of the stay 92a, or may penetrate the inner cylindrical space 92 separately from the stay 92a.
[0115]
Further, as shown in (b), the suction pipe 31 may be 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. Good. In the figure, the extension is denoted by reference numeral 93. 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.
[0116]
Thus, since the backflow from the impeller 20 flows through the inner cylindrical space 92, no positive pressure is generated in the vicinity of the air inlet 62 or it can be suppressed to a small positive pressure.
[0117]
The sixth embodiment will be described with reference to the partial cross-sectional view of FIG. (A) is a partial side sectional view showing only the periphery of the air chamber 50. FIG. (B) is X1-X1 arrow view (partial plane sectional view) which looked at the suction pipe in cross section at the position of the slit 51a. Similarly, referring to the partial side sectional views (c), (e), (g) and the corresponding partial planar sectional views (d), (f), (h), the sixth embodiment will be described. A modification will be described.
[0118]
In the present embodiment, a slit 51 a as an air inlet, which is similar to the slit of the first embodiment, is formed in the suction pipe 31 in an annular shape. The slit 51 a is formed in a slit shape that is a narrow gap along the air chamber 50, and communicates the air chamber 50 with the inside of the suction pipe 31. And it is comprised so that air may be sucked in in the suction pipe 31 through the air pipe 60 and the inlet 51a according to the fall of the pressure in the suction pipe 31.
[0119]
As shown in FIG. 5A, an air guide plate 71 that guides air flowing into the air chamber 50 from the air pipe 60 is disposed inside the outer wall of the annular air chamber 50 in the air chamber 50. As shown in (b), a plurality of air guide plates 71 are provided. In the present embodiment, eight are equally arranged in the circumferential direction of the annular air chamber. A plurality of air pipes 60, four in the present embodiment, are arranged equally in the middle of the air guide plate 71.
[0120]
The air guide plate 71 has a substantially rectangular shape as shown in (a), and is formed from below to above with the attachment position of the air pipe 60 to the air chamber 50 interposed therebetween. As shown in (b), the air guide plate 71 is formed radially in the air chamber 50. Further, as shown in (a) and (b), the horizontal tip of the air guide plate 71 is somewhat to the inner wall of the air chamber 50 (the casing wall of the suction pipe 31, in other words, the outer wall of the suction pipe 31). It arrange | positions with the gap | interval of.
[0121]
A modification of the sixth embodiment will be described with reference to (c) and (d). The air guide plate 71 is formed in the upper part of the annular air chamber 50 as shown in FIG. In this embodiment, it is formed radially (see (b)) so as to block the upper half of the air chamber (see (a)). Further, the air pipe 60 is formed from the center to the upper position of the attachment position of the air pipe 60 to the air chamber 50.
[0122]
(E) With reference to (f), another modification of the sixth embodiment will be described. The air guide plate 71 is arranged inside the outer wall of the annular air chamber 50 as shown in FIG. Further, as shown in the figure, the air chamber is formed from the lower wall to the upper wall from the lower side to the upper side. (E) As shown in (f), the tip of the air guide plate 71 is arranged with a certain amount of gap from the inner wall of the air chamber 50 (the outer wall of the suction pipe 31).
[0123]
(G) With reference to (h), another modification of the sixth embodiment will be described. This example is different from the cases (e) and (f) in that the tip of the air guide plate 71 is in contact with the inner wall of the air chamber 50. Therefore, the outer wall and the inner wall of the air chamber 50 are connected by the air guide plate 71. Therefore, the air chamber 50 is divided into a plurality of segments (small rooms) by the plurality of air guide plates 71. At this time, the air pipe 60 is preferably provided for each segment.
[0124]
According to the present embodiment, since the air guide plate 71 guides the air in the air chamber 50 to the suction pipe 31, it is easy to attract the air into the water.
[0125]
In the air / water mixing operation of the preceding standby operation pump, the pump operation point approaches the small water amount side on the QH curve. In the case of an axial flow or mixed flow pump, if the operating point is closer to the small amount of water, the total head and shaft power tend to increase. In particular, if an air lock rib is attached to the inner surface of the suction pipe (suction bell), the shaft power tends to be higher. This requires a prime mover with a large output, which is disadvantageous from the viewpoint of energy saving and cost reduction.
[0126]
According to this embodiment, since it is not necessary to provide the anti-swivel plate on the inner surface of the casing wall of the suction pipe, it is possible to suppress the pump shaft power increase during the air-water mixing operation and to operate with less energy. . However, it goes without saying that an air guide plate may be provided together with the turning prevention plate when the demand for turning prevention is great.
[0127]
【The invention's effect】
As described above, according to the present invention, since the annular air chamber is provided, air can be uniformly distributed, and since the anti-rotation plate is provided, it is possible to provide a vertical shaft pump that can prevent the swirling flow. It becomes possible.
[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 QH curve (performance curve) for explaining the characteristics of a vertical shaft pump.
FIG. 4 is a partial front sectional view for explaining a second embodiment of the present invention.
FIG. 5 is a front sectional view of a vertical shaft pump according to a third embodiment of the present invention.
FIG. 6 is a partial cross-sectional view illustrating a modification of the third embodiment of the present invention.
FIG. 7 is a partial cross-sectional view illustrating a fourth embodiment of the present invention.
FIG. 8 is a partial cross-sectional view illustrating a fifth embodiment of the present invention.
FIG. 9 is a partial cross-sectional view illustrating a sixth embodiment of the present invention.
FIG. 10 is a partial cross-sectional view illustrating a sixth embodiment of the present invention.
FIG. 11 is a front sectional view of a conventional vertical shaft pump.
[Explanation of symbols]
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
36 channels
50 Air chamber
50a Air chamber wall
51a slit
51b Air intake hole
52 slit
52a prop
60 air pipe
61 Open end
62 Air introduction hole
70 Anti-rotation plate
71 Air guide plate
81 nozzles
82 Nozzle hole
83 inner cylinder
84 Inner cylinder space
84a, 84b Inner cylinder stay
85 treatments
85a Treatment casing
85b Treatment stay
91, 93 inner cylinder
91a Inner cylinder stay
92 Inner cylinder space
h Negative pressure head
HWL high water level
Ld Design water level
LWL minimum water level
Lc Water level that draws air in a vortex
SWL Impeller starting water level
A1 Inlet water level
A2 Lower level of suction pipe

Claims (10)

An impeller that is rotated by a rotating shaft arranged in the vertical direction and sucks water in the water tank;
A suction pipe disposed upstream of the impeller and formed by a casing wall;
An air inlet is formed in the inner surface of the casing wall, and one end of the air inlet communicates with the air inlet, and the other end includes an air pipe that opens above the highest water level in the water tank;
The suction pipe has an inner cylinder that forms an annular inner cylinder space between the inner surface of the casing wall and the impeller and the intake port. An upstream side of the inner cylinder is the intake port Is connected to the inner surface of the casing wall, and the inner cylinder forms a tapered nozzle whose flow area decreases along the flow of water, and the inner cylinder space faces the impeller downstream. A hole is formed in the vicinity of the connection portion between the inner cylinder and the inner surface of the casing wall of the inner cylinder;
Vertical shaft pump. The suction pipe has an annular air chamber that surrounds the inner surface of the casing wall and is connected to one end of the air pipe, and the intake port extends along the air chamber so as to communicate the air chamber and the suction pipe. The vertical shaft pump according to claim 1 , which is formed in a slit shape. An impeller that is rotated by a rotating shaft arranged in the vertical direction and sucks water in the water tank;
A suction pipe disposed upstream of the impeller and formed by a casing wall, the suction pipe having an annular air chamber surrounding an inner surface of the casing wall;
An air pipe having one end connected to the air chamber and the other end opening above the highest water level in the water tank;
A slit-like air inlet that communicates the annular air chamber and the suction pipe is formed on the inner surface of the casing wall;
The suction pipe has an inner cylinder that forms an annular inner cylinder space between the impeller and the intake port and an inner surface of the casing wall, and the inner cylinder space includes the inner cylinder and the inner cylinder. A support plate for connecting the inner surface of the casing wall is disposed, the inner cylinder space is opened in the suction pipe in the vicinity of the intake port on the upstream side, and is opened facing the impeller on the downstream side;
Vertical shaft pump. The vertical shaft pump according to claim 2 or 3 , wherein a column that connects the inner surface of the casing wall between the upstream side and the downstream side is formed at the intake port across the intake port. An impeller that is rotated by a rotating shaft arranged in the vertical direction and sucks water in the water tank;
A suction pipe disposed upstream of the impeller and formed by a casing wall;
The suction tube have a cylindrical inner forming the inner tube an annular space between the inner surface of the casing wall;
An air pipe for introducing air into the suction pipe from one end, the air pipe further opening at the other end above the highest water level in the water tank;
The inner cylinder space is open downstream from the impeller;
An air inlet to the suction pipe by the air pipe opens into the inner cylinder;
Vertical shaft pump. The vertical shaft pump according to claim 5 , wherein the suction pipe is formed in a bell mouth shape, and an upstream side of the inner cylinder is extended along the bell mouth. An impeller that is rotated by a rotating shaft arranged in the vertical direction and sucks water in the water tank;
A suction pipe disposed upstream of the impeller and formed by a casing wall, the suction pipe having an annular air chamber surrounding an inner surface of the casing wall;
An air pipe having one end connected to the air chamber and the other end opening above the highest water level in the water tank;
An air inlet is formed on the inner surface of the casing wall, and the air chamber communicates with the inside of the suction pipe through the air inlet;
On the inner surface of the casing wall between the impeller and the intake port, a flat anti-rotation plate that prevents water from rotating due to the rotation of the impeller is directed in the radial direction and the axial direction of the suction pipe. It is formed;
The air inlet is formed in a slit shape along the annular air chamber ;
A column that connects the inner surface of the casing wall between the upstream side and the downstream side is formed at the intake port across the intake port ;
The support column constitutes an air guide plate having a tip projecting into the air chamber and guiding air flowing from the air chamber into the suction pipe ;
The air guide plate is inclined in the rotational direction of the impeller with respect to a radial direction centered on the rotational axis ;
Vertical shaft pump. An impeller that is rotated by a rotating shaft arranged in the vertical direction and sucks water in the water tank;
A suction pipe disposed upstream of the impeller and formed by a casing wall, the suction pipe having an annular air chamber surrounding an inner surface of the casing wall;
An air pipe having one end connected to the air chamber and the other end opening above the highest water level in the water tank;
A slit-like air inlet that communicates the annular air chamber and the suction pipe is formed on the inner surface of the casing wall;
The said air inlet is arranged an air guide plate for guiding the air flowing toward the suction pipe from the air chamber to protrude the tip to the air chamber;
The air guide plate is inclined in the rotational direction of the impeller with respect to a radial direction centered on the rotational axis ;
Vertical shaft pump. An impeller that is rotated by a rotating shaft arranged in the vertical direction and sucks water in the water tank;
A suction pipe disposed upstream of the impeller and formed by a casing wall, the suction pipe having an annular air chamber surrounding an inner surface of the casing wall;
An air pipe having one end connected to the air chamber and the other end opening above the highest water level in the water tank;
A slit-like air inlet that communicates the annular air chamber and the suction pipe is formed on the inner surface of the casing wall over the entire circumference of the suction pipe;
A casing treatment is formed between the air inlet and the impeller;
The casing treatment includes a casing wall of the suction pipe and an outer casing disposed outside the casing wall of the suction pipe, and a space between the casing wall of the suction pipe and the outer casing is one side. Is a return flow path that opens to the inlet blade end portion of the impeller and the other opens to the vicinity of the intake port, and water that flows in from the opening of the inlet blade end portion passes through the opening near the intake port. A return flow path having a length in the axial direction, which returns to the main flow at the center of the suction pipe ;
Vertical shaft pump. The vertical shaft pump according to claim 9 , wherein a pillar that connects the casing wall of the suction pipe between the upstream side and the downstream side is formed at the intake port across the intake port.

Images