JP3385511B2 - 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 shaft pump installed in a water absorption tank, and in particular, it is provided to enable a pumping operation even when the water level in the water absorption tank is lowered, for example, to drain water discharged during rainfall. The present invention relates to a vertical shaft pump that is suitable for performing the preceding standby operation described above and that can also be used for pump management operation in normal times.

[0002]

2. Description of the Related Art A conventional vertical shaft pump of this type is disclosed in Japanese Patent Laid-Open No.
As described in Japanese Patent Laid-Open No. 3-90697, the impeller is located slightly above the pump specific portion specific to the pump, which corresponds to the lowest water level when the pump is submerged below this level. There is a device which is provided so that when the water level becomes lower than the water level corresponding to the above-mentioned minimum water level level, it is made to idle by vacuum breaking so that the water is dropped to prevent drainage operation.

Further, as another conventional vertical shaft pump, as described in Japanese Utility Model Laid-Open No. 63-150097, an impeller is located at a position lower than the water level in the water absorption tank and externally provided near the inlet of the impeller. It is known that a through hole communicating with the through hole is provided, the through hole is connected to a pipe, and the other end of the pipe is opened near a level in the water absorption tank where the impeller is submerged in water.

[0004]

Generally, when performing a preliminary standby operation based on rainfall information or the like, it is desirable to perform a drainage operation at a water level as low as possible in view of an increase in storage effect of a water absorption tank or a pipe. In addition, it is effective to prevent the fullness and reduce the surge of the water absorption tank by setting the flow rate to an appropriate level according to the water level of the water absorption tank, which enables stable operation of the pump.

However, the former one of the above-mentioned prior arts does not consider drainage operation at a water level lower than the minimum water level, for example, from the suction port of the suction bell to a diameter of 1.4 to 1. Drainage operation is not possible at water levels lower than the seven times known minimum water level.

On the other hand, according to the latter of the above-mentioned conventional techniques, when the water level in the water absorption tank falls below the level of the opening, air is sucked in through the opening, so that the pumping action of the pump gradually increases as the water level decreases. Will be reduced to. Therefore, pumping operation is possible at low water level, and there is a characteristic that the transition to the idling state does not occur suddenly.For example, the pump idles and waits before a sudden inflow into the water absorption tank occurs. , Seems to be suitable for a pump that performs so-called standby operation. This vertical shaft pump
The other end of the pipe communicating with the through hole is opened near the level where the impeller in the water absorption tank is submerged, and air is sucked when the water level drops below this opening, so the pump starts the intake of water. Can be determined by the installation level of the opening.

However, when the water level is higher than the installation level of the opening, water is absorbed from the opening, so if foreign matter such as dust is contained in the pumped water, this foreign matter will close the opening with the lapse of operating time. However, there is concern that it may interfere with the inspiratory action. Especially in the drain pump that performs the preceding standby operation described above,
Since the rainwater that has fallen over a wide area of the city suddenly flows into the water absorption tank, various foreign substances may flow in.

Further, the latter is designed to increase the intake amount and decrease the drainage amount depending on the water level in the water absorption tank, that is, the lower the water level, but in order to perform the drainage operation while inhaling, Stable intake must be performed. However, no consideration is given to performing stable intake in this conventional technique.

SUMMARY OF THE INVENTION It is an object of the present invention to enable a stable drainage operation while sucking air in a vertical shaft pump that performs a preceding standby operation.

[0010]

The above problems can be solved by the following means.

First, in a vertical shaft pump which is installed in a water absorption tank and which starts the preparatory standby operation from a water level lower than the minimum water level level at which the water level during pump operation is lower than that which sucks air from the suction bell of the pump casing, An intake hole provided in a pump casing below an impeller forming a vertical shaft pump, and an intake pipe having one end connected to the intake hole, the intake pipe extending upward toward the other end side, It is characterized in that it is provided so as to extend downwardly so that its end portion is directed downward in the water absorption tank, and a rib is provided on the inner surface of the pump casing near the intake hole.

By thus providing the rib (or the protruding portion) near the intake hole (or the intake portion), the swirling flow near the intake hole can be prevented or reduced, so that the influence of the swirling flow is minimized. It is possible to do the limit and to perform stable intake.

Further, since the rib has a taper portion on the upstream side of the position of the intake hole, foreign matter can be prevented from being caught on the rib. Further, it is preferable to provide a plurality of ribs on the inner surface of the pump casing below the impeller at substantially equal intervals in the circumferential direction. Here, the rib or the protruding portion may be provided upstream or downstream of the intake hole position. When it is provided on the upstream side of the intake hole, the static pressure of the intake hole or the intake portion can be easily lowered, and the intake action can be reliably performed.

Further, the intake hole or the intake portion may be formed so as to project into the pump casing. In addition, the intake part,
It may be provided so as to be inclined with respect to the flow direction in the pump casing.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on embodiments. 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 accommodating the impeller 1, and the pumping pipe 5 and the discharge pipe 5 which are a part of the pump casing 4 are provided on the upper side. The elbow 6 is connected to form a vertical shaft pump. A discharge pipe 7 and a discharge valve 8 are provided on the discharge side of the discharge elbow 6. An intake hole 9 is provided near the lower part of the impeller 1, and an intake pipe 10 is provided in connection with the intake hole 9.
Further, the intake pipe 10 is provided with an intake amount control valve 11 so that the intake port 12 of the intake pipe 10 has a maximum water level (HW) in the water absorption tank 20.
L) is installed at a higher position. The flow rate control device is configured by these. The intake hole 9 is provided at a position where the intake hole 9 is not inhaled at the conventional lowest water level level, that is, at the lowest water level WL1 peculiar to the pump that sucks air from the lower end of the suction bell 3 at or below this water level. The static pressure P (m) at the intake hole 9 is expressed by the following equation.

P = Po + L−hs−k · v ² / (2g) (1) where Po: atmosphere (10.33 m), L: (water level) (m), hs: pump casing suction part loss Head (m), v: Flow velocity (m) of the liquid handled in the intake hole, k: Constant If the static pressure P in the intake hole is greater than Po, no air intake, so L> hs + k · v ² / (2g) By doing so, it does not inhale. Therefore, the intake hole 9 is provided at a position lower than the conventional lowest water level WL1 by L ₁ = hs + k · v ² / (2g). As a result, the water level L is WL
Since intake is not performed in the range A of 1 or more, drainage operation can be performed with a predetermined pump capacity. In the range B where the water level is lower than WL1, L decreases in the equation (1), so P
Becomes smaller than atmospheric pressure and inhales. Since an appropriate amount of intake air is given by the intake air amount control valve 11, an appropriate amount of air intake is performed according to the water level to control the flow rate. Range B
In the case where the water level is WL2, P is slightly low due to the atmospheric pressure, so the intake amount is small and the flow rate of the pump also slightly decreases. In this case, since the submersion depth S1 of the pump is sufficient for the pump flow rate at this time, no vortex occurs. When the water level is WL3, P decreases almost in proportion to the decrease of the water level, so P becomes smaller than atmospheric pressure, the intake amount increases, the flow rate of the pump also decreases significantly, and vortices are generated even at the submersion depth S2. A flow rate that does not occur can be used. When the water level is WL4, the intake amount is 15% to 20% of the pump flow rate.
It becomes impossible to pump water and becomes idling. The submersion depth S3 at this time is designed such that the suction bell inlet level is such that a vortex does not occur at the flow rate immediately before the pumping is disabled. In addition, the opening and closing of the intake air amount control valve 11 may be constant in the entire range where the water level changes, or the opening degree may be changed depending on the water level. Vortices do not occur even at the conventional minimum water level WL1 or less, and safe operation without abnormal vibration or noise becomes possible. At a water level at which the impeller 1 is slightly submerged from idle operation to drain operation, and at a water level slightly higher than the water level WL4 at which drain operation is changed to idle operation, the flow rate of the pump is controlled to about half of the predetermined flow rate by intake air. Since there is little change in the flow rate when drainage starts and when drainage stops, the surge phenomenon is mitigated and stable pump operation is possible. Reference numeral 21 is a low wall of the suction water tank (water absorption tank) 20.

Here, it is desirable that the level difference L ₁ between the conventional minimum water level WL ₁ and the installation position of the intake hole 9 is L ₁ = hs + k · v ² / (2g) from the relationship of the equation (1). . However, L ₁ is determined by the easiness of eddy generation, and is generally a function of the pump diameter. The right side of the above equation is a function of v, but v is different depending on the discharge amount of the pump, the total head of the specification, the specific speed, etc. . Therefore, if k = 1 is fixed, the pump cannot always plan the pressure at the point P equal to the atmospheric pressure. That is, a low pump having pump head is a large _{diameter, L 1> hs + k ·} v 2 / (2g) , and the high pump of pump head is a relatively small diameter in the opposite small _{L 1,} v since becomes large, _{L 1} > Hs + k · v ² / (2
g). Therefore, it is desirable that k can take a value other than 1 in hs + k · v ² / (2g). A specific embodiment in which k can take a value other than 1 will be described with reference to FIGS.

FIG. 2 shows the first embodiment of the intake hole of the present invention, and is a detailed view showing the vicinity of the intake hole 9 in FIG. In the pump casing 2 near the inlet of the impeller, 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 so as to be inclined with respect to a plane perpendicular to the pump axis in the direction of flow in the pump casing. Therefore, the static pressure P (m) in the intake hole 9 has a value of k> 1 when expressed by the above-mentioned equation (1). On the other hand, as in the second embodiment of the present invention shown in FIG. 3, if the intake hole 9 is provided so as to be inclined in the direction opposite to the flow in the pump casing, then 0 <k <1. In this way, the intake hole 9 is provided so as to be inclined with respect to the plane perpendicular to the pump axis, whereby the value of k in the equation (1) can be increased or decreased from 1.

In FIG. 4, instead of inclining the intake hole in the embodiment of FIG. 2, the intake hole end portion is formed by a curved pipe protruding into the pump casing. That is, the intake pipe 10 is penetrated through the pump casing, the tip of the intake pipe 10 is bent, and the opening is peeled in a direction inclined at an angle of α ° with respect to the flow direction in the pump casing to form the intake hole 9. It was done. By this angle α,
The value of k in equation (1) 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 intake hole of the present invention, in which the intake hole 9 is provided below the position of the minimum inner diameter Dmin of the suction bell 3 of the pump casing. Since the diameter of the attachment portion of the intake hole 9 is larger than Dmin, the static pressure is higher than that of the Dmin portion, so that k <1. The value of k can be easily changed by appropriately selecting the position of the intake hole from a position near the Dmin portion to a position near the inlet (diameter D _B ) of the suction bell 3.

FIG. 7 shows a fifth embodiment of the intake hole according to the present invention, in which a projecting portion 2a is provided on the inner wall surface of the pump casing above the intake hole 9 (downstream side). FIG. 8 shows a sixth embodiment, in which the protruding portion 9a is provided at the lower portion (upstream side) of the intake hole.
I have In FIG. 7, since the flow is blocked by the protrusion 2a, the static pressure of the intake hole provided immediately upstream thereof becomes high, and k <1. On the other hand, in FIG.
Since the intake hole is provided immediately downstream of a, 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, etc. of the protrusion.

Thus, by the method shown in FIGS.
Since the value of k in equation (1) can be adjusted up or down below 1.0,
For pumps of various sizes, specific speeds and full heads, the static pressure P at the intake hole 9 can be made equal to the atmospheric pressure Po at the conventional lowest water level WL1.

2 to 8, the number of intake holes is equal to or greater than the number of impeller blades, or is an integral multiple of the number of impellers, and each intake hole is in the circumferential direction of the pump casing. It is better to provide them at equal intervals. According to the results of experiments by the inventors, when only one intake hole is provided, the air from the intake hole does not uniformly flow into each blade passage of the impeller, so that the impeller has a fluid unbalanced force. Was observed, and the phenomenon that the vibration of the pump increased was observed. On the other hand, by providing a plurality of intake holes, particularly equal to or more than the number of impeller blades, or by providing an integral multiple of the number of impellers, and providing them at equal intervals in the circumferential direction, The operation is stable, and the air flows evenly between the pump blades, and the pump vibration can be reduced.

Next, still another embodiment of the present invention will be described with reference to FIG.
~ It demonstrates by FIG.

9 and 10 show an impeller 1 of a vertical shaft pump.
A plurality of intake holes 9 are provided so as to protrude inward from the inner wall surface of the suction bell 3 of the suction part. The intake hole 9 is
The intake pipe 10 opens to the atmosphere. Further, the intake hole 9 is an opening 3 connected to the suction bell at one end of the intake pipe 10.
The inner wall surface of the suction bell 3 is provided with a rib 25 having a ventilation hole 25a communicating with the opening 3a, and a communication hole 25a is provided in the rib 25, so that the communication hole 25a is located more than the inner surface of the suction bell. It is formed by opening the inside. The rib 25 is preferably manufactured by means such as casting so as to be integrated with the suction bell 3. Further, the rib 25 is provided in the axial direction of the pump as shown in the figure, and acts to prevent or reduce the swirling flow near the intake hole. Furthermore, rib 2
5 extends downward from the vicinity of the communication hole 25a, and the height of the upper end of the rib from the inner wall surface of the suction bell coincides with the position of the opening end of the intake hole 9, and the height of the lower end of the rib is the height of the upper end. It has a taper shape that is lower than that.

In the present embodiment, the opening end position of the intake hole 9 is located inside the inner wall surface of the pump casing (suction bell 3), but the height h of the intake hole 9 from the inner wall surface of the casing is h.
Is preferably set to satisfy the following expression (2), where R ₁ is the radius of the casing inner wall surface at the intake hole position.

H ≧ 0.2R ₁ (2) The reason for this will be described with reference to FIG. FIG. 11 shows the magnitude of the flow velocity in the circumferential direction (horizontal axis) at the inlet of the pump impeller, that is, in the vicinity of the intake hole, for each point facing inward (in the pump casing central axis direction) from the inner wall surface of the pump casing. The straight line a has a flow coefficient of 6
When it is 0% or more, the curve b is the same, and when it is 50%, the curve c is the same.
Is also 40% and curve d is also 20%,
From this figure, at the point where r / R ₁ is about 0.8 or less,
The flow velocity in the circumferential direction is significantly smaller than that at the point above 0.8. 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 (2), the influence of the swirling flow velocity can be reduced and the centrifugal force due to the swirling can be reduced, so that a sufficient and stable intake air can be obtained. Therefore, the vibration can be reduced.

In each of the above-described embodiments, a plurality of intake holes are provided, but by using two or more intake holes, stable intake is performed and pump vibration can be reduced with reference to FIG. . FIG. 12 is experimental data for confirming the relationship between the number of intake holes and pump vibration. Curve e shows a change in the vibration ratio when 1 to 20 intake holes are provided on the inner wall of the suction bell. f is the embodiment of FIG. 9, in which the height h of the intake hole from the inner wall surface of the suction bell is 0.2R ₁ with respect to the radius R _{1 of the} inner wall surface of the casing at the intake hole position, It shows the change in the vibration ratio when the number of is 1 to 20. As shown in this figure, by setting the number of the intake holes to 2 or more, the pump vibration can be significantly reduced as compared with the case where the number of the intake holes is 1. In particular, the pump vibration can be made extremely small by setting the number of intake holes to 5 or more. This experimental data is for the case where the number of pump blades is 5, and the number of intake holes is equal to or more than the number of pump blades, and by providing them at equal intervals in the circumferential direction, air can be evenly flowed between the blades. It can be seen that the pump vibration can be reduced. Further, as shown by the curve f, it can be seen that when the intake holes are provided inside the suction bell inner wall surface, the pump vibration can be significantly reduced even if the number of the intake holes is two.

13 and 14 show another embodiment of the present invention. In this embodiment, a tapered rib 26 is provided on the inner wall surface of the suction bell 3 of the pump casing 4, two intake holes 9 are provided adjacent to the rib 26, and they are located on the inner wall surface of the suction bell 3 at opposing positions. It is provided. The intake hole 9 is opened to the atmosphere by an intake pipe 10. Also in this embodiment, the same effect as that 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 ribs 5, so that the pressure fluctuation at the position of the intake hole 9 is small, 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 hole 9 becomes lower than the atmospheric pressure, so that the intake pipe 10 takes in air. At this time, the intake hole 9 is located near the inlet of the pump impeller and is not easily affected by the swirling flow, so that there is little fluctuation in pressure and stable intake is possible. Further, since the influence of the centrifugal force due to the swirling flow is small, a sufficient intake amount can be obtained. From the above, it is possible to reduce the vibration of the pump, and by providing the tapered rib 5 in the lower portion of the intake hole 4, the intake hole portion can be reinforced and foreign matter is not blocked in the rib 5 or the intake hole portion. effective.

As described above, according to each embodiment of the present invention, the following effects are obtained. First, if the pump casing is provided with a plurality of intake holes, it is possible to stabilize the amount of intake air and reduce vibration when performing drainage operation while performing intake air.

Further, according to the one in which the opening end position of the intake hole in the pump casing is inside the inner wall surface of the pump casing, or the rib for preventing the swirling flow is provided close to the intake hole. Since the effect of the swirling flow near the inlet of the pump impeller can be reduced and the centrifugal force of the fluid is also reduced, sufficient and stable intake air can be obtained, and pump vibration can be reduced.

Further, according to the shape in which the suppression pressure of the intake hole can be increased or decreased, the water level at which intake is started can be set to a desired water level.

If the number of intake holes is equal to or greater than the number of blades of the impeller, the intake air can be evenly distributed to the inter-blade passages of the impeller, so that increase in pump vibration during intake can be prevented. effective.

Further, an impeller is provided below the lowest water level, an intake hole is provided in the pump casing below the impeller, an intake pipe is connected to the intake hole, and an intake port of the intake pipe is sucked. According to the one opened to the atmosphere at a position higher than the maximum water level in the water tank, it is possible to prevent foreign matter from adhering to the suction port of the intake pipe and impeding the intake action.

[0036]

As described above, according to the present invention,
In the vertical shaft pump that performs the preceding standby operation, it is possible to perform stable drainage operation while taking in air.

[Brief description of drawings]

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

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

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

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

5 is a diagram showing the relationship between the direction (angle α °) of the intake holes in FIG. 4 and a constant k in equation (1).

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

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

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

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

10 is a view taken along line XX in FIG.

FIG. 11 is a diagram showing the flow velocity in the circumferential direction 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 cross-sectional view showing the main parts of the eighth embodiment of the present invention.

FIG. 14 is a view taken along the line YY of FIG.

[Explanation of symbols]

1 impeller 2 casing liner 3 suction bell 4 pump casing 5 Pumping pipe 6 Discharge elbow 7 Discharge pipe 8 discharge valve 9 Intake hole 10 Intake pipe 11 Intake volume adjustment valve 12 Suction port 20 water absorption tank 25 ribs 26 ribs

Front page continuation (56) References: 1-76588 (JP, U): 1-176790 (JP, U): 63-140199 (JP, U): 63-121793 (JP) , U) Actual development Sho 55-161085 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F04D 13/00

Claims (8)

(57) [Claims] 1. A vertical pump that is installed in a water absorption tank and starts the preparatory standby operation from a water level lower than the minimum water level level at which the water level during pump operation is lower than that of the suction bell of the pump casing, An intake hole provided in a pump casing below an impeller forming a vertical shaft pump, and an intake pipe having one end connected to the intake hole, the intake pipe extending upward toward the other end side,
Then, the vertical shaft pump is provided so as to extend downward and its end portion is directed downward in the water absorption tank, and a rib is provided on an inner surface of the pump casing near the intake hole. 2. The vertical shaft pump according to claim 1, wherein the rib has a tapered portion upstream of the position of the intake hole. 3. The vertical shaft pump according to claim 1, wherein the ribs are provided on the inner surface of the pump casing below the impeller at substantially equal intervals in the circumferential direction. 4. A vertical axis pump which is installed in a water absorption tank and which starts the preceding standby operation from a water level lower than the minimum water level level at which the water level during pump operation is below that which sucks air from the suction bell of the pump casing, An intake hole provided in a pump casing below an impeller forming a vertical pump and an intake pipe having one end connected to the intake hole, the intake pipe extending upward toward the other end side,
Then, the vertical shaft pump is provided so as to extend downward and its end portion is directed downward in the water absorption tank, and a protrusion is provided on an inner surface of the pump casing near the intake hole. 5. The vertical pump according to claim 4, wherein the protruding portion is provided on the upstream side of the intake hole position. 6. The vertical shaft pump according to claim 4, wherein the protruding portion is provided on the downstream side of the intake hole position. 7. A vertical pump that is installed in a water absorption tank and that starts the preparatory standby operation from a water level lower than the minimum water level level below which the air is sucked from the suction bell of the pump casing when the water level during pump operation is lower than that, An intake portion provided in a pump casing below an impeller forming a vertical pump and an intake pipe having one end connected to the intake portion are provided. One end side of the intake pipe is projected into the pump casing and The suction pipe is formed, and the suction pipe is configured to extend upward toward the other end side and then downward so that the end portion faces downward into the water absorption tank. Vertical pump to do. 8. A vertical axis pump that is installed in a water absorption tank and starts the preparatory standby operation from a water level lower than a minimum water level level at which the water level during pump operation is lower than that which sucks air from the suction bell of the pump casing, An intake part provided in a pump casing below an impeller forming a vertical pump and an intake pipe having one end connected to the intake part, the intake pipe extending upward toward the other end side,
Then, the vertical shaft pump extends downward and its end is provided downward in the water absorption tank, and the intake is inclined with respect to the flow direction in the pump casing. .