JPH03271599A - Vertical shaft pump - Google Patents

Abstract

PURPOSE:To obtain a vertical shaft pump for restricting the reverse to be generated in an inlet of an impeller and for obtaining the sufficient and stabilized suction air and for reducing the vibration in the case of the exhausting operation with the air suction by providing multiple turn-preventing plates on the internal surface of a pump casing between an impeller and suction holes. CONSTITUTION:A suction bell mouth 3 is connected to a lower end of a pump casing 2 which is equipped with an impeller 1 therein. In this case, in the pump casing 2 near an inlet of the impeller 1, multiple suction holes 9 opening on the internal surface of the casing 2 are provided, and multiple rectangular turn-preventing plates 13 arriving near the inlet of the impeller 1 are provided in the internal surface of the pump casing 2 over (just over, downstream side) the suction holes 9 along the pump axial direction. The turning flow is made to collide with the turn-preventing plates 13 to lose the energy thereof. Consequently, the reverse flow does not arrive the suction holes 9 to eliminate instability of the suction air to be caused by the reverse, and the vibration is restricted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vertical shaft pump installed in a water suction tank, and in particular, enables pumping operation even when the water level in the water suction tank is low, such as during rain. The present invention relates to a vertical shaft pump that is suitable for carrying out a preliminary standby operation for draining out water, and that allows for easy management operation of the pump during normal times.

[Prior Art] A conventional vertical shaft pump of this type is disclosed in Japanese Patent Application Laid-Open No. 63-90697.
As stated in the publication, an impeller is installed at a position slightly above a specific part of the pump that corresponds to the lowest water level below which air will be sucked in when the pump is submerged. When the water level is lower than the water level, there is one that breaks the vacuum and enters a idling state, causing the water to fall and disabling the drain operation.

In addition, as other conventional vertical shaft pumps,
As described in Publication No. 50097, an impeller is positioned below the water level of the water absorption tank, and a through hole leading to the outside is provided near the inlet of one impeller, and the through hole is connected to a pipe to connect the limb pipe. It is known that the other end is provided with an opening in the water absorption tank near the level where the impeller is submerged.

[Problems to be Solved by the Invention] Normally, in order to perform advance standby operation based on rainfall information, etc., it is necessary to perform drainage operation at the lowest possible water level because the storage effect of water absorption tanks and pipes increases. Setting a flow rate that is desirable and appropriate according to the water level of the water absorption tank is effective in preventing vortices and preventing surge phenomena in the water absorption tank, and enables stable operation of the pump.

Furthermore, it is required that vibration and noise do not increase even when the displacement of the pump is reduced and the pump is operated in a low flow range.

However, in any of the above conventional techniques, no consideration was given to the influence of backflow occurring at the impeller inlet when the pump is operated in a low flow rate region when draining is performed while taking in air.

In other words, in the flow rate range where backflow occurs, in the case of any of the conventional technologies, there is a possibility that the backflow will reach the intake hole installed below the impeller, and the backflow will make the intake condition unstable. is possible.

The present invention has been made in order to solve the problems of the prior art described above, and it suppresses the backflow occurring at the impeller inlet, thereby making it possible to obtain sufficient and stable intake air, and to prevent vibrations caused when draining operation is performed while drawing air. We aim to provide a vertical shaft pump that can reduce
That is the purpose.

[Means for Solving the Problems] In order to achieve the above object, the configuration of the first invention related to the vertical shaft pump of the present invention is such that when the water level during pump operation is lower than that, air is removed from the suction bell mouth of the pump casing. An impeller is arranged below the position corresponding to the lowest water level that sucks in water, and a plurality of intake holes are provided in the pump casing below the impeller that open to the inner wall surface of the pump casing. In a vertical shaft pump equipped with an intake pipe having one end connected to the pump and the other end opened to the atmosphere at a level higher than the highest water level of the pump water suction tank, on the inner wall surface of the pump casing between the impeller and the intake hole. In addition, a plurality of rotation prevention plates are provided.

In addition, in order to achieve the above object, the configuration of the second invention related to the vertical shaft pump of the present invention is such that the water level during pump operation is the lowest water level below which air is sucked from the suction bell mouth of the pump casing. An impeller is arranged below the position corresponding to the level, and a plurality of intake holes are provided in the pump casing below the impeller that open to the inner wall surface of the pump casing, and one end is connected to this intake hole and the other end is connected to the pump casing. In a vertical shaft pump equipped with an intake pipe whose end is opened to the atmosphere at a level higher than the highest water level of a pump water intake tank, a constriction part that narrows the inner diameter is formed on the inner wall of the pump casing between the impeller and the intake hole. .

The intake hole is located below the constriction part.

[Operation] The operation of the above technical means will be explained with reference to FIGS. 2 and 3.

21st! 1 and FIG. 3 are 9. 1. It is an explanatory view of the operation of the second invention.

Generally, when an intake hole is provided in the pump casing and drainage operation is performed while taking in air, the intake hole is located close to the pump impeller, so it is affected by the swirling backflow from one impeller. It is known that because the pressure at the intake hole position becomes unstable, the amount of intake air is unstable and vibrations occur.

Therefore, it is necessary to stabilize the intake air by preventing the backflow from reaching the position of the intake hole.

In the first invention, as shown in FIG. 2, a rotation prevention plate 13 is provided on the inner wall surface of the pump casing 2 between the impeller 1 and the intake hole 9 that opens on the inner wall surface of the pump casing. In the flow area.

This design suppresses the swirling component of the backflow that occurs on the inner wall of the pump casing, forming a circulation as shown by the arrow from the impeller inlet upstream and back to the impeller. Stability is prevented, the intake air amount is stabilized, impeller load fluctuations are suppressed, and stable operation with less vibration can be performed.

Further, in the second invention, as shown in FIG.
By forming a constriction part 14 whose inner diameter is narrower than the inner diameter of the pump casing between the intake hole 9 that opens on the inner wall surface of the pump casing, the range where the backflow reaches the upstream side of the impeller inlet at low flow rates is limited. By providing the intake hole below this point, the influence of backflow can be prevented from reaching the intake hole.
For the same reason as with the rotation prevention plate of the first invention, stable operation with less vibration can be performed.

[Embodiments] Hereinafter, each embodiment of the present invention will be described with reference to FIGS. 1, 4 to 7.

FIG. 1 is a schematic configuration diagram of a vertical shaft pump to which the present invention is applied, and FIG. 4 is a longitudinal sectional view of essential parts on the impeller inlet side according to an embodiment of the present invention (first invention). 5(a) is a view taken along the line 2-2 in FIG. 4, and FIG. 5(b) is a view taken along the X-ray arrow in FIG.

First, in FIG. 1, a suction bell mouth 3 constituting a part of the pump casing is connected to the lower side of a pump casing 2 equipped with an impeller 1 inside, and a part of the pump casing is connected to the upper side. Lifting pipes 5. A discharge elbow 6 is connected to constitute a vertical shaft pump.

A discharge pipe 7 and a discharge valve 8 are arranged on the discharge side of the discharge elbow 6. Further, a plurality of (four in the figure) air intake holes 9 are formed slightly below the impeller 1 on the inner wall surface of the pump casing 2, and an air intake pipe 10 is connected to the air intake holes 9. Further, an intake air amount adjusting valve 1 is provided in the intake pipe 10.
1 is provided, and the suction port 12 of the intake pipe 10 is installed in the water suction tank 20 at a position higher than the highest water level (HWL), and these constitute a flow rate control device.

The intake hole 9 is provided at a position where air is not drawn from the intake hole 9 at the conventional lowest water level, i.e., at the lowest water level WLI specific to the pump, air is sucked in from the lower end of the suction bell mouth 3 below this water level. There is. In FIG. 1, it is placed at a distance a from the top of the impeller 1.

4 and 5 show one embodiment of the first invention, and are detailed views showing the vicinity of the intake hole 9 in FIG. 1.

The pump casing 2 near the inlet of the impeller 1 has a plurality of intake holes 9 opening on the inner wall surface of the casing, and the inner wall surface of the pump casing above the intake holes 9 (directly above, on the downstream side), A plurality of substantially rectangular anti-swivel cutouts 3 reaching near the inlet of the impeller 1 are provided in the pump axial direction. In Figure 5.

As an example, a case is shown in which there are four turning prevention punches 3.

When a vertical shaft pump is operated in a low flow rate region, a backflow is generated from the impeller 1 toward the inlet side, but it is known that this backflow is a strong swirling flow directed in the rotation direction of the impeller 1.

When this swirling flow reaches the swirl prevention plate 13.

When the flow collides with the rotation prevention plate 13, the energy of the swirling flow is lost. Therefore, the backflow does not reach the intake hole 9 provided below the rotation prevention plate 13,
Or even if it reaches the point, the energy of the backflow is significantly reduced, so the instability of intake air due to backflow is eliminated, and vibrations are suppressed.

Next, FIG. 6 is a sectional view of the main part showing the positional relationship between the anti-swivel plate and the intake hole according to the first embodiment of the present invention. Z-Z line arrow view in Fig. 4,
This corresponds to another example of the X-ray arrow view.

In the embodiment shown in FIG. 6, the anti-swivel plate 13 is not located above (directly above) the intake holes 9, but is placed in the middle of the pitches of the four intake holes 9.

Even in this case, effects similar to those of the embodiment shown in FIGS. 4 and 5 can be obtained.

Next, FIG. 7 is a main part sectional view showing the positional relationship between the rotation prevention plate and the intake hole according to still another embodiment of the present invention (first invention), and (a) and (b) thereof. The figures are Fig. 6(a), (
It is a figure corresponding to b).

In the embodiment shown in FIG. 7, the anti-swivel plate 13A is located in the middle of the pitch of the intake holes 9, and the lower end of the anti-swivel plate 13A extends below (upstream) from the intake hole 9. It is something that

Even in this case, effects similar to those of the embodiment shown in FIGS. 4 and 5 can be obtained.

According to each embodiment of the first invention, a plurality of rotation prevention plates 13 (13A) are provided between the intake hole opened on the inner wall surface of the pump casing 2 and the impeller 1. 1
It is possible to suppress the backflow that occurs in one impeller, to obtain sufficient and stable intake air, and to reduce vibrations when draining operation is performed while drawing air. , Next, FIG. 8 is a vertical sectional view of a main part on the impeller inlet side according to an embodiment of the present invention (second invention), and FIG.
- It is a Y line arrow view. In the figure, the same reference numerals as those in FIG. 4 are the same parts as in the embodiment of the first invention, so the explanation thereof will be omitted.

As shown in FIGS. 8 and 9, on the inner wall of the pump casing 2 near the inlet of the impeller 1, a constriction part 14 that narrows the inner diameter of the inner wall is formed between the inlet of the impeller 1 and the intake hole 9. A plurality of (for example, four) intake holes 9 are arranged in the constriction part 1.
It is located below 4.

With this configuration, the backflow is blocked by the throttle part 14, and the backflow is prevented from reaching the upstream side of the throttle part 14. That is, the reverse flow from the impeller 1 toward the inlet side becomes a flow toward the center of the casing due to the throttle portion 14.

Therefore, the area where strong backflow occurs is limited to between the impeller 1 and the throttle section 14, and the backflow is significantly reduced in the intake hole 9 located below the throttle section. Therefore, intake air is stabilized and vibrations are suppressed.

According to the embodiments of the second invention, the same effects as those of the embodiments of the first invention are expected.

[Effects of the Invention] As described in detail above, according to the present invention, backflow occurring at the impeller inlet is suppressed, sufficient and stable intake air is obtained, and vibrations that occur when draining operation is performed while drawing air are also suppressed. It is possible to provide a vertical shaft pump that can reduce the amount of water used.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a vertical shaft pump to which the present invention is applied, and FIGS. The action explanatory diagram of the second invention, FIG.
FIG. 5(a), a longitudinal cross-sectional view of the main part of the impeller inlet side according to an embodiment of the invention), is a view taken along the line 2-2 in FIG. 4, and FIG.
b) is an X-ray arrow view of FIG. 4, and FIG. 6 is a view of the present invention (first
FIG. 7 is a cross-sectional view of a main part showing the positional relationship between the rotation prevention plate and the intake hole according to another embodiment of the present invention (first invention). FIG. 8 is a cross-sectional view of the main part showing the positional relationship between the plate and the intake hole; FIG. 8 is a longitudinal cross-sectional view of the main part on the impeller inlet side according to an embodiment of the present invention (second invention);
FIG. 9 is a view taken along the Y--Y line in FIG. 8. 1... Impeller, 2... Pump casing, 3...
Suction bell mouth, 9... Intake hole, 10... Intake pipe,
13゜13A... Rotation prevention plate, 14... Throttle part.

Claims (1)

[Claims] 1. If the water level during pump operation is lower than that, air will be sucked in from the suction bell mouth of the pump casing.
The pump casing below this impeller is provided with a plurality of intake holes that open on the inner wall surface of the pump casing, one end of which is connected to the intake holes, and the other end is exposed to the atmosphere at a level higher than the highest water level of the pump water intake tank. A vertical shaft pump having an open intake pipe, characterized in that a plurality of anti-swivel plates are provided on an inner wall surface of a pump casing between the impeller and the intake hole. 2. The vertical shaft pump according to claim 1, wherein the plurality of intake holes are located below the plurality of rotation prevention plates. 3. The vertical shaft pump according to claim 1, wherein the plurality of rotation prevention plates are located between the plurality of intake holes. 4. If the water level during pump operation is lower than that, air will be sucked in from the suction bell mouth of the pump casing.The impeller is placed below the position corresponding to the lowest water level,
The pump casing below this impeller is provided with a plurality of intake holes that open on the inner wall surface of the pump casing, one end of which is connected to the intake holes, and the other end is exposed to the atmosphere at a level higher than the highest water level of the pump water intake tank. In a vertical shaft pump having an open intake pipe, a constriction portion narrowing the inner diameter is formed on an inner wall of the pump casing between the impeller and the intake hole, and the intake hole is located below the constriction portion. This vertical shaft pump is characterized by: