JP2889306B2 - Vertical pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vertical pump installed in a water absorption tank,
In particular, the pumping operation can be performed even when the water level in the water absorption tank is low, and it is suitable for, for example, performing a preliminary standby operation that is performed to drain water during rainfall. The present invention relates to a vertical shaft pump.

[Prior Art] A conventional vertical pump of this type, as described in JP-A-63-90697, has a water level when the pump is submerged below the water level corresponding to the minimum water level at which air is sucked. An impeller is provided at a position slightly above the pump specific portion specific to the pump, and when the water level becomes lower than the water level corresponding to the above minimum water level, the pump is idled by vacuum breakage, so that the water is dropped and the drainage operation cannot be performed. There is something.

Another conventional vertical shaft pump is disclosed in
As described in Japanese Patent Publication No. 0097, the impeller is located at a position lower than the water level of the water absorption tank, a through hole is provided near the inlet of the impeller, and the through hole is connected to a pipe. It is known that the other end is provided with an opening in a water absorption tank near a level where the impeller is submerged.

[Problems to be Solved by the Invention] 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. Desirably,
In addition, setting the flow rate to an appropriate value according to the level of the water in the water absorption tank is effective in preventing vortices and surge phenomenon in the water absorption tank, and enables stable operation of the pump.

It is also required that vibration and noise do not increase even when the pump is operated in a low flow rate region due to a decrease in the drainage amount of the pump.

However, in the above prior art, in each case,
When the drainage operation is being performed while suction is being performed, the influence of the backflow generated at the impeller inlet in the low flow rate operation of the pump has not been considered.

That is, in the flow rate region where the backflow occurs, in any of the conventional technologies, the backflow may reach the intake hole provided below the impeller, and the backflow may cause the intake state to be unstable. Can be

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the related art, and suppresses a backflow generated at an inlet of an impeller, thereby obtaining a sufficient and stable intake air. It is an object of the present invention to provide a vertical shaft pump capable of reducing the pressure.

Means for Solving the Problems In order to achieve the above object, the first invention according to the vertical pump according to the present invention has a structure in which the water level during the operation of the pump is below, and the water level is below the suction bell mouth of the pump casing. The impeller is disposed below a position corresponding to the lowest water level at which the air is sucked, and a plurality of intake holes that are opened on the inner wall surface of the pump casing are provided in a pump casing below the impeller. A vertical axis pump having an intake pipe whose one end is connected to the other end and whose other end is opened to the atmosphere at a level higher than the highest water level of the pump water absorption tank, on the inner wall surface of a pump casing between the impeller and the intake hole. To
A plurality of turning prevention plates are provided to prevent backflow from the impeller.

Further, in order to achieve the above object, the configuration of the second invention according to the vertical pump of the present invention, the water level during the operation of the pump,
Below that, air is sucked from the suction bell mouth of the pump casing, an impeller is disposed below the position corresponding to the lowest water level, and the pump casing below the impeller opens to the inner wall surface of the pump casing. A vertical pump having an intake pipe having a plurality of intake holes, one end of which is connected to the intake holes, and the other end of which is opened to the atmosphere at a level higher than the highest water level of the pump suction tank, wherein the impeller and the impeller A throttle portion for narrowing the inner diameter is formed on the inner wall of the pump casing between the suction hole and the suction hole, and the suction hole is located below the throttle portion.

[Operation] When the swirling flow reaches the anti-swirl plate by the above technical means, the flow collides with the anti-swirl plate, so that the energy of the swirling flow is lost. Because the backflow has stopped reaching or the energy of the backflow has decreased significantly even if it has reached,
The instability of intake air due to backflow is eliminated, and vibration is suppressed.

For reference, a specific example of the operation of the present invention will be described in detail below with reference to FIGS. 2 and 3.

In general, when a pump casing is provided with an intake hole and the drainage operation is performed while suction is being performed, the intake hole is provided near the pump impeller, so that the intake hole is affected by the swirling backflow from the impeller, It is known that since the pressure at the position of the intake hole becomes unstable, the amount of intake air becomes unstable and vibration occurs.

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, the rotation preventing plate 13 is provided on the inner wall surface of the pump casing 2 between the impeller 1 and the intake hole 9 opened on the inner wall surface of the pump casing, thereby reducing the rotation. In the flow rate region, the swirl component generated by the backflow, which is generated on the inner wall side of the pump casing from the impeller inlet toward the upstream and forms a circulation as shown by an arrow returning to the impeller, is suppressed, so that the position of the intake hole due to the backflow Is stabilized, the intake air amount is stabilized, the load fluctuation of the impeller is suppressed, and stable operation with less vibration can be performed.

In the second aspect of the present invention, as shown in FIG. 3, a throttle portion 14 having a smaller inner diameter than the inner wall of the pump casing is formed between the impeller 1 and the intake hole 9 opened on the inner wall surface of the pump casing. By limiting the range in which the backflow at a low flow rate reaches the upstream side of the impeller inlet, and by providing an intake hole below it, it is possible to prevent the influence of the backflow from affecting the intake hole,
A stable operation with less vibration can be performed for the same reason as in the turning prevention plate of the first invention.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 4 to 7.
This will be described with reference to the drawings.

FIG. 1 is a schematic structural view of a vertical pump to which the present invention is applied. FIG. 4 is a longitudinal sectional view of a main part of an impeller inlet side according to an embodiment of the present invention (first invention). FIG. 5 (a) is a view taken along the line ZZ in FIG. 4, and FIG. 5 (b) is a view taken along the line X in FIG.

First, in FIG. 1, a suction bell mouth 3 constituting a part of a pump casing is connected to a lower part of a pump casing 2 provided with an impeller 1 therein, and a part of the pump casing is provided on an upper side. Are connected to the pumping pipe 5 and the discharge elbow 6 which constitute a vertical shaft pump.

A discharge pipe 7 and a discharge valve 8 are provided on the discharge side of the discharge elbow 6. In addition, slightly below the impeller 1, a plurality of openings (4 in FIG.
), An intake pipe 10 is provided in connection with the intake hole 9, an intake amount adjusting valve 11 is provided in the intake pipe 10, and a suction port 12 of the intake pipe 10 is connected to a water absorption tank. Among them, they are installed at a position higher than the highest water level (HWL), and these constitute a flow control device.

The intake hole 9 is provided at a position which is not sucked from the intake hole 9 at the conventional minimum water level, that is, at a pump-specific minimum water level WL1 at which the air is sucked from the lower end of the suction bell mouth 3 below this water level. I have. In FIG. 1, it is provided at a distance l from the upper part of the impeller 1.

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

The pump casing 2 near the inlet of the impeller 1 has a plurality of intake holes 9 opened on the inner wall surface of the casing, and the pump casing inner wall surface above (substantially right above and downstream of) the intake holes 9. A plurality of substantially rectangular turning prevention plates 13 reaching near the entrance of the vehicle 1 are provided in the pump axial direction. FIG. 5 shows a case where the number of the turning prevention plates 13 is four as an example.

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

When the swirling flow reaches the anti-swirl plate 13, the flow collides with the anti-swirl plate 13 and energy of the swirling flow is lost. Therefore, the backflow does not reach the intake hole 9 provided below the turning prevention plate 13, or even if it does, the energy of the backflow is significantly reduced.
Instability of intake air due to backflow is eliminated, and vibration is suppressed.

Next, FIGS. 6A and 6B are main-part sectional views showing a positional relationship between a turning prevention plate and an intake hole according to another embodiment of the present invention (the first invention). 4 corresponds to another example of the view taken along the line ZZ and the view taken along the arrow X in FIG.

In the embodiment shown in FIG. 6, the turning prevention plate 13 is provided not at the upper part (almost right above) of the intake holes 9 but at the center of the pitch of the four intake holes 9.

Even in this case, the same effect as the embodiment shown in FIGS. 4 and 5 can be obtained.

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

In the embodiment shown in FIG. 7, the turning prevention plate 13A is provided in the middle of the pitch of the intake holes 9, and the lower end of the turning prevention plate 13A is provided to extend downward (upstream side) from the intake holes 9. It is a thing.

Even in this case, the same effect as the embodiment shown in FIGS. 4 and 5 can be obtained.

According to each embodiment of the first invention, a plurality (for example, four) of anti-rotation plates 13 (13A) are provided between the intake hole opened in the inner wall surface of the pump casing 2 and the inlet of the impeller 1. Therefore, the backflow generated at the entrance of the impeller 1 can be suppressed, sufficient and stable intake can be obtained, and the vibration in the case of performing the drainage operation while performing the intake can be reduced.

Next, FIG. 8 is a longitudinal sectional view of a main part on the impeller entrance side according to one embodiment of the present invention (second invention), and FIG. 9 is a view taken along line YY of FIG. is there. In the figure, components having the same reference numerals as those in FIG. 4 are the same as those in the embodiment of the first invention, and therefore the description thereof is 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 throttle portion for reducing the inner diameter of the inner wall is provided.
14 is formed between the inlet of the impeller 1 and the intake holes 9, and a plurality (for example, four) of the intake holes 9 are located below the throttle unit 14.

With this configuration, the backflow is blocked by the throttle unit 14 and the backflow is prevented from reaching the upstream side of the throttle unit 14. That is, the reverse flow from the impeller 1 toward the inlet side is a flow toward the center of the casing by the throttle portion 14. For this reason, the region where strong backflow occurs is caused by the impeller 1 and the throttle portion 14.
And the backflow is significantly reduced in the intake hole 9 located below the throttle portion. Therefore, the intake air is stabilized, and the vibration is suppressed.

According to the embodiment of the second invention, the same effect as each embodiment of the first invention is expected.

[Effects of the Invention] As described above in detail, according to the present invention, the backflow generated at the impeller inlet is suppressed, sufficient and stable intake air is obtained, and the vibration during drainage operation while sucking air is also reduced. A vertical shaft pump that can be reduced can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of a vertical shaft pump to which the present invention is applied. FIGS. 2 and 3 are operation explanatory diagrams of the first and second aspects of the vertical shaft pump of the present invention. The present invention (first
FIG. 5 (a) is a sectional view taken along the line ZZ in FIG. 4, and FIG. 5 (b) is a sectional view of a fourth embodiment of the present invention. FIG. 6 is a cross-sectional view of a main part showing a positional relationship between a turning prevention plate and an intake hole according to another embodiment of the present invention (the first invention), and FIG. FIG. 8 is a sectional view of a main part showing a positional relationship between a rotation preventing plate and an intake hole according to still another embodiment of the present invention (first invention), and FIG.
FIG. 9 is a vertical sectional view taken along the line YY of FIG. 8 according to an embodiment of the present invention). DESCRIPTION OF SYMBOLS 1 ... Impeller, 1 ... Pump casing, 3 ... Suction bell mouth, 9 ... Intake hole, 10 ... Intake pipe, 13, 13A ... Rotation prevention plate, 14 ... Restrictor.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F04D 13/00 F04D 29/66 F04D 29/44

Claims (2)

(57) [Claims] An impeller is disposed below a position corresponding to a minimum water level at which a water level during operation of a pump is lower than a level at which air is sucked from a suction bell mouth of a pump casing. A plurality of intake holes that are opened on the inner wall surface of the pump casing, and one end is connected to the intake hole and the other end is opened to the atmosphere at a level higher than the highest water level of the pump water absorption tank. A vertical shaft pump comprising: a plurality of rotation preventing plates provided on an inner wall surface of a pump casing between the impeller and the intake hole to prevent backflow from the impeller. pump. 2. An impeller is disposed below a position corresponding to a minimum water level at which a water level during operation of the pump is below which air is sucked from a suction bell mouth of the pump casing. A plurality of intake holes that are opened on the inner wall surface of the pump casing, and one end is connected to the intake hole and the other end is opened to the atmosphere at a level higher than the highest water level of the pump water absorption tank. A vertical shaft pump comprising: a throttle portion for reducing the inner diameter of an inner wall of a pump casing between the impeller and the suction hole; wherein the suction hole is located below the throttle portion. Vertical shaft pump.