JP2899648B2 - Vertical pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical pump installed in a water absorption tank, and more particularly to a vertical pump installed in a water absorption tank to enable pumping operation even when the water level in the water absorption tank is low, for example, for draining out water during rainfall. The present invention relates to a pump which is suitable as a vertical pump for performing a preceding standby operation and can be used for a pump management operation in normal times.

[0002]

2. Description of the Related Art A conventional vertical shaft pump of this type is disclosed in
As described in -90697, an impeller is provided at a position slightly higher than a pump-specific pump specific portion corresponding to a minimum water level at which the water is sucked when the water level at the time of submersion of the pump is below this level. When the water level becomes lower than the water level corresponding to the minimum water level, there is a type in which a vacuum break is performed to make the wheel idle, and the water is dropped to prevent the drainage operation.

As another conventional vertical shaft pump, as described in Japanese Utility Model Application Laid-Open No. 63-150997, an impeller is located at a position lower than the water level of a water absorption tank, and an external pump is provided near an inlet of the impeller. It is known that a through hole is provided to communicate with a pipe, and the through hole is connected to a pipe, and the other end of the pipe is provided with an opening in a water absorption tank near a level where the impeller is submerged.

[0004]

Normally, in performing the preliminary standby operation based on rainfall information or the like, the drainage operation can be performed at the lowest possible water level because the storage effect of the water absorption tank and the sewer increases. It is desirable to set the flow rate to be appropriate and appropriate in accordance with the water level of the water absorption tank, which is effective for preventing vortices and reducing surges in the water absorption tank, and enables stable operation of the pump.

However, the former one of the above-mentioned prior arts does not take into consideration draining operation at a water level lower than the minimum water level, and for example, the diameter of the suction bell is 1.4 to 1.7 times the diameter of the suction bell. Drainage operation cannot be performed at a water level lower than the known minimum water level.

According to the latter of the above prior arts,
If the water level of the water absorption tank falls below the level of the opening, air is sucked in from the opening, and the pumping action of the pump gradually decreases with the drop of the water level. This characteristic is suitable for a pump that performs a so-called advance standby operation in which the pump idles and waits before an abrupt inflow into the water absorption tank occurs, for example. In this vertical shaft pump, the other end of the pipe communicating with the through hole is opened near the level at which the impeller in the water absorption tank is submerged, and air is sucked when the water level falls below this opening. There is a feature that the water level at which intake is started can be determined by the installation level of the opening.However, when the water level is higher than the set level of the opening, water is absorbed from the opening. In such a case, there is a concern that the foreign matter closes the opening with the elapse of the operation time and inhibits the intake operation. In particular, in the above-described drain pump that performs the preliminary standby operation, since rainwater that has fallen over a wide area of the city rapidly flows into the water absorption tank, various foreign substances may flow in.

Further, in the latter, the amount of intake air is increased and the amount of drainage is decreased in accordance with the water level in the water absorption tank, that is, as the water level becomes lower. Stable intake must be performed. However, this prior art does not take into consideration stable air intake.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vertical standby pump of a preceding standby operation type capable of preventing the influence of swirling flow and performing stable intake.

Another object of the present invention is to prevent a suction operation from being hindered by the adhesion of foreign matter in a water absorption tank, to obtain a safe and reliable suction operation, and to set a water level at which suction is started to a desired water level. To obtain a vertical pump.

It is still another object of the present invention to uniformly flow air from the suction hole into the pump casing, thereby minimizing vibration of the pump caused by suction.

[0011]

The present invention SUMMARY OF THE INVENTION To achieve the above object, the water level in the pump operation, lower level than the lowest water level that will crowded have intake air from the suction bell of the pump casing is less In the vertical pump that starts the preliminary standby operation from the beginning, an intake hole is provided in the pump casing below the impeller constituting the vertical shaft pump, one end is connected to the intake hole, and the other end is at a level higher than the highest water level of the pump water suction tank. Provide an open intake pipe, close to the intake hole
Thus, a rib protruding from the inner surface of the pump casing is provided to reduce the influence of the swirling flow near the intake hole.

[0012] Other features of the present invention, vertical-shaft pump water level in the pump operation, to start the preceding standby operation from a low level than the lowest water level that will crowded have intake air from the suction bell of the pump casing is less , A plurality of suction holes are provided in the circumferential direction of the pump casing below the impeller constituting the vertical shaft pump, one end of which is connected to the suction holes and the other end of which is opened to a level higher than the highest water level of the pump suction tank. the intake pipe is provided, the rib projecting into the pump casing inner surface between said plurality of intake holes formed in the circumferential direction is provided, said ribs thereon projecting height of the pump casing
Formed with a taper that increases in the direction
It has been.

Next, the operation of the present invention will be described. ◆ In the vicinity of the position of the intake hole provided near the pump impeller, since the sucked water is swirling and flowing, the centrifugal force of the water acts on the intake hole, and sufficient negative pressure occurs at the position of the intake hole. Pressure is not available,
Therefore, a sufficient intake amount cannot be obtained.

In the present invention, since the swirling flow near the intake hole can be prevented or reduced by providing the rib or the protruding portion in the vicinity of the intake hole, the influence of the swirling flow can be minimized and stable. Inspiration can be performed.

By providing a plurality of intake holes in the pump casing, the amount of intake air can be stabilized. In particular, if the number of intake holes is equal to or more than the number of blades of the impeller of the pump, or an integer multiple of the number of blades, and they are provided at equal intervals in the circumferential direction, the flow path between the pump blades The air from the intake hole can be made to flow uniformly, and a stable operation with less vibration can be performed.

Further, in the present invention, since the opening of the intake pipe to the atmosphere is provided at a position higher than the highest water level of the water absorption tank as described above, the air is floated in the water in the water absorption tank at the opening. It does not occur that foreign substances such as dust are adsorbed and the intake action at the time of lowering the water level is hindered.

Further, the intake hole provided in the pump casing at the impeller inlet is provided to be inclined with respect to a plane perpendicular to the pump axis, or to be provided at a position shifted downward from the minimum inner diameter portion. Alternatively, the pressure in the opening can be increased or decreased by using the flow in the pump casing by means such as providing a projection on the inner wall surface of the pump casing at the upper or lower part of the intake hole. On the other hand, at the water level of the water absorption tank where you want to start intake,
The pressure in the opening can be made equal to the atmospheric pressure, so that the air supply operation can be performed at the following water level.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the suction bell 3 of the pump casing is connected to the lower side of the casing liner 2 of the pump casing 4 in which the impeller 1 is housed, and the pumping pipe 5 which is a part of the pump casing 4 and the upper side. The discharge elbow 6 is connected to form a vertical pump. On the discharge side of the discharge elbow 6, a discharge pipe 7 and a discharge valve 8 are provided. In addition, an intake hole 9 is provided near the lower portion of the impeller 1, an intake pipe 10 is provided in connection with the intake hole 9, and an intake air amount adjusting valve 11 is provided in the intake pipe 10. The suction port 12 is the highest water level (HW
L) It is installed at a higher position. These constitute a flow control device. The intake hole 9 is provided at a position where the air is not sucked from the intake hole 9 at the conventional minimum water level, that is, at the minimum water level WL1 specific to the pump in which air is sucked from the lower end of the suction bell 3 below this water level. The static pressure P (m) at the intake hole 9 is represented by the following equation.

P = Po + l−h _s −k · υ ² / 2g where Po: air (10.33 m), l: (water level) (m), h _s : head loss of pump casing suction part ( m), υ: flow rate (m) of the liquid handled in the suction hole, k: constant.

If the static pressure P at the intake hole becomes larger than Po, no intake is performed. Therefore, if l> h _s + k · υ ² / 2g, no intake is performed. Therefore, the conventional minimum water level WL
_{1 L 1 = h s + k} · υ 2 / 2g simply by providing inlet openings 9 in a position lower than at the lower. Therefore, since the intake is not performed when the water level is in the range A of WL1 or more, the drainage operation can be performed with a predetermined pump capacity. In the range B where the water level is lower than WL1, 1 decreases in the equation, so that P becomes smaller than the atmospheric pressure and the air is taken. The intake air amount is controlled by the intake air amount adjusting valve 11.
Since an appropriate loss is given, an appropriate amount of intake is performed according to the water level to control the flow rate. In the range B, when the water level is WL2, P is slightly lower due to the atmospheric pressure, so the intake air amount is small, and the flow rate of the pump is also slightly reduced. In this case, since the submersion depth S1 of the pump is sufficient for the pump flow at this time, no vortex occurs. Water level is W
In the case of L3, P decreases almost in proportion to the decrease in the water level, so that it becomes smaller than the atmospheric pressure, the intake air amount increases, the flow rate of the pump decreases significantly, and no vortex occurs even at the submerged depth S2. It can be a flow rate. When the water level is WL4, the intake air amount becomes 1.5% to 20% of the pump flow rate, making it impossible to pump up water and entering an idling operation state. Submersion depth S at this time
3 designs the level of the suction bell inlet so that vortex does not occur at the flow rate immediately before pumping is impossible. Note that the opening of the intake air amount control valve 11 may be constant over the entire range in which the water level fluctuates, or the opening may be changed depending on the water level. Conventional minimum water level WL1
Even in the case below, no vortex is generated, and safe operation without abnormal vibration or noise can be performed. At a water level at which the impeller 1 that shifts from the idling operation to the pumping operation is slightly submerged and at a water level slightly higher than the water level WL4 that shifts from the drainage operation to the idling operation, the flow rate of the pump is controlled to about half of a predetermined flow rate by the suction. Therefore, there is little change in the flow rate at the start of drainage and at the time of drainage stop, the surge phenomenon can be reduced, and the pump can operate stably. Reference numeral 21 denotes a low wall of the suction water tank (water absorption tank) 20.

Now, the conventional minimum water level WL
1 and the level difference L1 between the intake holes 9 installation position, from the equation of the relationship, it is desirable that the _{L 1 = h s + k ·} υ 2 / 2g, L 1 is determined from the generation ease of vortex, generally It is a function of the diameter of the pump, and the right side of the above equation is a function of υ. Since υ varies depending on the pump discharge amount, the specified total head, the specific speed, etc., if k = 1 is fixed, the pump Therefore, the pressure at the point P cannot always be planned to be equal to the atmospheric pressure. That is, for a large diameter pump with a low head, L
₁ > h _s + k · υ ² / 2g. Conversely, a pump having a relatively small diameter and a high head has a small L ₁ and a large υ, so that L ₁ <
h _s + k · υ ² / 2g. Therefore, h _s + k · υ ²
It is desirable that k can take a value other than 1 in / 2g. A specific embodiment in which k can take a value other than 1 will be described with reference to FIGS.

FIG. 2 shows a first embodiment of the present invention.
FIG. 2 is a detailed view showing the vicinity of an intake hole 9 in FIG. 1. In the pump casing 2 near the impeller inlet, a plurality of intake holes 9 are provided at equal intervals in the circumferential direction of the pump casing 2. The intake hole 9 is provided to be inclined in the direction of flow in the pump casing with respect to a plane perpendicular to the pump axis. Therefore, the static pressure P (m) in the intake hole 9
Is represented by the above equation, the value of k is k> 1. On the other hand, in the second embodiment of the present invention shown in FIG. 3, since the intake hole 9 is provided to be inclined in the direction opposite to the flow in the pump casing, 0 <k <1. By providing the intake hole 9 at an angle to the plane perpendicular to the pump axis, the value of k in the equation can be increased or decreased from 1.

FIG. 4 shows the embodiment of FIG. 2 in which, instead of inclining the intake hole, the end of the intake hole is formed by a curved pipe projecting into the pump casing. That is, the intake pipe 10 penetrates the pump casing, and the intake pipe 1
The intake hole 9 is formed by bending the front end of the opening 0 so as to open the opening in a direction inclined by α ° with respect to the flow direction in the pump casing. Depending on the angle α, the value of k in the equation changes as shown in FIG. Therefore, the value of k can be easily increased or decreased by appropriately selecting the angle α.

FIG. 6 shows a fourth embodiment of the present invention.
The intake hole 9 is provided below the position of the minimum inner diameter _Dmin of the suction bell 3 of the pump casing. The diameter of the air intake holes 9 mounting part static pressure is higher than D _min portion is greater than D _min, that is, k <1. The value of k is determined by setting the position of the intake hole closer to the D _min portion than the suction bell 3.
Can be easily changed by appropriately selecting a point close to the entrance (diameter D _B ).

FIG. 7 shows a fifth embodiment of the present invention, in which a protruding portion 2a is provided on the inner wall surface of the pump casing above (downstream) the intake hole 9. FIG. 8 shows a sixth embodiment in which a protruding portion 9a is provided at a lower portion (upstream side) of the intake hole. In FIG. 7, since the flow is dammed up by the protruding portion 2a, the static pressure of the intake hole provided immediately upstream thereof increases, and k <1. On the other hand, in FIG. 8, since the intake hole is provided immediately downstream of the protruding portion 9a, the static pressure of the intake hole is low, and k> 1. Thus, the value of k can be easily changed by appropriately selecting the position, size, shape, and the like of the protruding portion.

As described above, the value of k in the equation can be adjusted to be larger or smaller than 1.0 by the method shown in FIGS. 2 to 8, so that pumps of various sizes, specific speeds, and full heads can be used with the conventional minimum water level. At the level WL1, the static pressure P at the intake hole 9 is changed to the atmospheric pressure Po.
Can be made equal to

In FIGS. 2 to 8, the number of suction holes is set equal to or more than the number of blades of the impeller, or an integral multiple of the number of blades, and each of the suction holes is formed in a circumferential direction of the pump casing. It is good to provide at equal intervals in the direction. According to the experimental results of the inventors, when only one intake hole is provided, the air from the intake hole does not uniformly flow into each blade flow path of the impeller, so that the fluid unbalance force is applied to the impeller. Acted, and a phenomenon that the vibration of the pump increased was observed. On the other hand, by providing a plurality of intake holes, in particular, equal to or more than the number of blades of the impeller, or by providing an integral multiple of the number of blades, and providing them at equal intervals in the circumferential direction, the intake is stabilized. In this way, air flows evenly between the pump blades, and pump vibration can be reduced.

Next, still another embodiment of the present invention will be described with reference to FIGS.

FIGS. 9 and 10 show an impeller 1 of a vertical shaft pump.
The suction portion has a plurality of suction holes 9 protruding inward from the inner wall surface of the suction bell 3. The intake hole 9 is the intake pipe 1
0 is open to the atmosphere. In addition, the suction hole 9 forms an opening 3a connected to one end of the suction pipe 10 in the suction bell, and the inner wall surface of the suction bell 3 communicates with the opening 3a. A rib 25 having a ventilation hole 25a is provided, the communication hole 25a is provided, and the communication hole 25a is formed by opening the communication bell 25 inside the inner surface of the suction bell. The rib 25 is preferably manufactured by means such as casting so as to be integrated with the suction bell 3. Further, as shown in the figure, the rib 25 is provided in the axial direction of the pump, and functions to prevent or reduce a swirling flow near the intake hole. Furthermore, rib 2
5 extends downward from the vicinity of the communication hole 25a, the height of the upper end from the inner wall surface of the suction bell matches the position of the opening end of the suction hole 9, and the height of the lower end of the rib is the height of the upper end. It is configured to have a tapered shape lower than that.

In this embodiment, the opening end position of the suction hole 9 is located inside the inner wall surface of the pump casing (suction bell 3), but the height of the suction hole 9 from the inner wall surface of the casing is h.
Is preferably set to satisfy h ≧ 0.2R ₂ ... When the radius of the inner wall surface of the casing at the position of the intake hole is satisfied. The reason for this is shown in FIG.
This will be described below. FIG. 11 shows the magnitude (horizontal axis) of the flow velocity in the circumferential direction of the flow near the inlet of the pump impeller, that is, in the vicinity of the intake hole, for each point from the inner wall surface of the pump casing toward the inside (toward the central axis of the pump casing). The line a is measured when the flow coefficient of the pump is 60% or more.
Curve b is also 50%, curve C is also 40%,
Curve d is also for 20%. From this figure, r /
At the point where R ₂ is about 0.8 or less, the circumferential flow velocity is much smaller than at the point where R ₂ is 0.8 or more. Therefore, if the height h of the intake hole 9 from the inner wall surface of the casing is determined so as to satisfy the above expression, the influence of the swirling flow rate can be reduced, and the centrifugal force due to the swirling is reduced, so that sufficient and stable intake can be obtained. , Vibration can be reduced.

In each of the above-described embodiments, a plurality of intake holes are provided. However, it will be described with reference to FIG. 12 that stable intake is performed by reducing the number of intake holes to two or more and pump vibration can be reduced. . FIG. 12 shows experimental data obtained by confirming the relationship between the number of suction holes and pump vibration. Curve a shows a change in vibration ratio when 1 to 20 suction holes are provided on the inner surface of the suction bell. f in the embodiment of FIG. 9, the intake hole of the height h from the suction bell inner wall surface of the intake hole to the casing inner wall surface radius R ₂ of the suction pores position, in that the position of the 0.2 R ₂ 3 shows the change in the vibration ratio when the number is 1 to 20. As shown in this figure,
By setting the number of intake holes to two or more, the number of intake holes becomes one.
, Pump vibration can be greatly reduced. In particular,
By setting the number of intake holes to 5 or more, pump vibration can be extremely reduced. This experimental data is for a case where the number of pump blades is five. By setting the number of intake holes equal to or more than the number of pump blades and providing them at equal intervals in the circumferential direction, air can be uniformly flowed between the blades. It can be seen that the pump vibration can be reduced. Also, as shown by the curve f, when the suction holes are provided inside the suction bell inner wall surface, it can be seen that even if the number of suction holes is two, the pump vibration can be significantly reduced.

FIG. 13 and FIG. 14 show still another embodiment of the present invention. In this embodiment, the pump casing 4
A tapered rib 26 is provided on the inner wall surface of the suction bell 3 and two intake holes 9 are provided adjacent to the rib 26 at opposing positions on the inner wall surface of the suction bell 3. The intake hole 9 is opened to the atmosphere by an intake pipe 10. In this embodiment, the same effects as those of the embodiment of FIG. 9 can be obtained. That is, even if a swirling flow occurs near the inlet of the pump impeller 1, the swirling flow can be suppressed by the rib 5, so that the pressure fluctuation is reduced at the position of the intake hole 9 and stable and sufficient intake can be performed.
The vibration of the pump can be reduced.

Next, the operation of the embodiment shown in FIGS. 9 and 13 will be described. In these embodiments, when the pump is operated at a low water level, the pressure in the intake port 9 becomes lower than the atmospheric pressure. At this time, since the intake hole 9 is located at a position near the inlet of the pump impeller where it is hard to be affected by the swirling flow, pressure fluctuation is small and stable intake can be performed. In addition, since the influence of the centrifugal force due to the swirling flow is small, a sufficient amount of intake air can be obtained. From the above, the vibration of the pump can be reduced, and
By providing the tapered rib 5 at the lower part of the rib, the intake hole can be reinforced, and there is an effect that foreign matter does not clog the rib 5 and the intake hole.

[0034]

According to the present invention, since the rib for preventing the swirling flow is provided near the intake hole, the influence of the swirling flow near the inlet of the pump impeller can be reduced, and the centrifugal force of the liquid can be reduced. Therefore, there is an effect that sufficient and stable intake air can be obtained and pump vibration can be reduced.

Further, by providing a plurality of air intake holes in the pump casing, the air can be stably and uniformly sucked into the pump casing.

Still further, according to the present invention, an impeller is provided below the lowest water level, an intake port is provided in a pump casing below the impeller, and an intake pipe is connected to the intake port. Is opened to the atmosphere at a position higher than the highest water level of the water absorption tank, so that there is an effect of preventing foreign substances from adhering to the suction port of the intake pipe and obstructing the suction operation.

[Brief description of the drawings]

FIG. 1 is an overall side view of a vertical shaft pump to which the present invention is applied.

FIG. 2 is a detailed vertical sectional view of a main part showing the first embodiment of the present invention.

FIG. 3 is a detailed vertical sectional view of a main part showing a second embodiment of the present invention.

FIG. 4 is a detailed vertical sectional view of a main part showing a third embodiment of the present invention.

5 is a diagram showing the relationship between the direction (angle α °) of an intake hole in FIG. 4 and a constant k in the above equation.

FIG. 6 is a detailed vertical sectional view of a main part showing a fourth embodiment of the present invention.

FIG. 7 is a detailed vertical sectional view of a main part showing a fifth embodiment of the present invention.

FIG. 8 is a detailed vertical sectional view of a main part showing a sixth embodiment of the present invention.

FIG. 9 is a detailed vertical sectional view of a main part showing a seventh embodiment of the present invention.

FIG. 10 is a view taken along line XX of FIG. 9;

FIG. 11 is a diagram showing the circumferential flow velocity of the flow near the inlet of the pump impeller measured at each point in the radial direction.

FIG. 12 is a diagram showing a relationship between the number of intake holes and pump vibration.

FIG. 13 is a detailed vertical sectional view of a main part showing an eighth embodiment of the present invention.

FIG. 14 is a view taken along the line YY in FIG. 13;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Impeller, 2 ... Casing liner, 3 ... Suction bell, 4
... pump casing, 5 ... water pipe, 6 ... discharge elbow, 7
... discharge pipe, 8 ... discharge valve, 9 ... intake hole, 10 ... intake pipe, 1
DESCRIPTION OF SYMBOLS 1 ... Intake amount adjustment valve, 12 ... Suction port, 20 ... Water absorption tank, 2
5, 26 ... rib.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F04D 13/00 F04D 29/54

Claims (2)

(57) [Claims] Level according to claim 1 During pump operation, the vertical shaft pump to begin prior standby operation from below at a lower level than the lowest water level that will crowded have intake air from the suction bell of the pump casing, constituting a vertical spindle pump An intake hole is provided in the pump casing below the impeller to be connected, one end is connected to the intake hole, and the other end is provided with an intake pipe opened to a level higher than the highest water level of the pump water absorption tank, and the intake pipe is provided close to the intake hole. Pump casing
A vertical shaft pump having a rib protruding from the inner surface to reduce the influence of swirling flow near the intake hole. Water level wherein the pump operation, the vertical shaft pump to begin prior standby operation from below at a lower level than the lowest water level that will crowded have intake air from the suction bell of the pump casing, constituting a vertical spindle pump A plurality of intake holes are provided in the circumferential direction of the pump casing below the impeller, and a plurality of intake pipes having one end connected to the intake hole and the other end opened to a level higher than the highest water level of the pump water absorption tank, Projecting into the inner surface of the pump casing between the plurality of intake holes provided in the circumferential direction ;
A rib provided that, the rib has its protrusion height Ponpukeshi
Has a taper that increases as it goes upward
A vertical shaft pump characterized by being formed .