JPH11148498A - Suction channel for vertical shaft pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen loss in a suction port by avoiding rapid change in direction in water flow, lessen loss in a suction channel by avoiding collision between both flows different in direction, dissolve unbalance in suction, elimiate the formation of stagnation, restrain the occurrence of vortexes in water, and prevent the occurrence of abnormal noise and vibration. SOLUTION: An upstream end part of a vertical wall 5 at the side of a side wall 7A and a downstream end part of the side wall 7A, are swelled out in a circular arc shape to the side of a first center line C1, a tongue part 10 is formed, which sets its tip end 10A at a position where an angle of f θ=45 deg. is formed from the first center line C1 toward a second center line C2 in the upstream side beyond the second center line C2 of a suction hole 3. A bottom part 8 of a duct in a circular arc shape is inclined so as to be formed into a rising gradient from a boundary between the vertical wall 5 located over the second center line C2 and the other side wall 7B, over the tip end 10A of the tongue part 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a suction channel for a vertical shaft pump, and more particularly to a suction channel for a large vertical shaft pump for rainwater drainage and irrigation.

[0002]

2. Description of the Related Art FIGS. 4 to 6 show known suction channels for a vertical shaft pump of this kind. This suction channel is constructed by concrete, and the vertical pump 1
And an umbrella-shaped bulging portion 4 surrounding the suction hole 3 and bulging downward. The umbrella-shaped bulging portion 4 has a downstream half. A standing wall 5 continuing to the radially outward bulging start end, a ceiling 6 in the upstream half of the umbrella-shaped bulging portion 4 continuing to the radially outward bulging starting end, and both sides continuing to the upstream end of the vertical wall 5 and the ceiling 6 Walls 7A, 7B and both side walls 7
A space is provided which is surrounded by a bottom portion 8 which is continuous with A, 7B and a lower end of the standing wall 5. A truncated conical raised portion 9 is formed on a bottom portion 8 facing below the suction hole 3.

Therefore, when the vertical pump 1 is operated, a substantially horizontal flow of water is guided by the umbrella-shaped bulging portion 4 and suddenly changes its direction upward at a substantially right angle, passes through the suction hole 3 and passes through the suction port 2. Therefore, the flow in the suction hole 3 is disturbed and the loss increases. This loss is significantly increased by reducing the width of the suction channel and increasing the flow velocity, so that the reduction of the width of the channel is restricted, preventing the suction channel from being made more compact.

On the other hand, a pre-swirl type suction channel shown in FIG. 7 is known. The suction channel includes a suction port 2 and a suction hole 3.
Downstream of a second center line C2 that is orthogonal to the first center line C1 extending in the flow direction of the suction channel through the center P
Thus, the tongue 10 protruding toward the center P is formed on the standing wall 5.

[0005] According to such a pre-swirl type suction water channel, the flow of water rises while swirling while interfering with the tongue portion 10, passes through the suction hole 3, and is sucked into the vertical shaft pump 1 from the suction hole 3. Since the upward direction change is gentler than that of the suction channel described with reference to FIGS. 4 to 6, the turbulence of the flow in the suction hole 3 is reduced, and the loss is somewhat reduced. However, as shown by arrows X1 and X2, flows in opposite directions occur on the deeper side than the second center line C2, and they collide with each other.
A relatively large loss occurs before being sucked into the suction hole 3.

On the other hand, in this suction channel, a considerable amount (more than 1/2) of water is sucked in the hatched portion of the suction hole 3 on the upstream side of the second center line C2. The amount of water flowing around the center line C2 toward the back side is reduced. For this reason, the suction state of the suction hole 3 becomes uneven in the circumferential direction, and the suction performance of the vertical shaft pump 1 is reduced. In addition, a "stagnation portion" having an extremely slow flow is generated on the back side of the second center line C2, and an underwater vortex is easily generated here, and the generated underwater vortex is sucked into the suction hole 3 and the suction port 2. When the vertical pump 1 enters the vertical pump 1, abnormal vibration and noise are generated in the vertical pump 1.

The applicant of the present invention has already proposed in Japanese Patent Laid-Open Publication No. Hei 8-109893 a suction channel for a vertical shaft pump which has solved these disadvantages. As shown in FIGS. 8 and 9, the suction channel of this vertical pump has a closed cross-sectional structure including a ceiling 6, a bottom 8, and both side walls 7A and 7B, and extends in the water flow direction. A vertical suction hole 3 communicating with the suction port 2 of the vertical shaft pump 1 is formed.
A small-diameter frusto-conical raised portion 9 is erected at the bottom portion 8 so as to face the first central line C1 extending through the suction port 2, the suction hole 3 and the center P of the raised portion 9 in the water flow direction. Orthogonal second
Behind the center line C2, there is provided a standing wall 5 which is continuous with the ceiling 6, the bottom 8 and the side walls 7A, 7B on both sides, and the upstream end of the standing wall 5 in one region of the first center line C1 and one end thereof. A tongue 10 is formed in which the downstream end of the side wall 7A is bulged in an arc shape toward the first center line C1 and joined at the tip 10A,
The position of the tip 10A of the tongue 10 is set to a position immediately upstream of the suction hole 3 on the first center line C1, and the upstream end of the standing wall 5 in the other area of the first center line C1, ie, the second end
The radius of curvature of the inner surface of the standing wall 5 from the boundary between the standing wall 5 on the center line C2 and the other side wall 7B to the tip 10A of the tongue portion 10 is continuously and gradually reduced toward the boundary 10A, The cross-sectional area of the arc-shaped channel 11 formed between the frusto-conical raised portion 9 and the upright wall 5 at the back of the second center line C2 is reduced steplessly.

In the suction channel of the vertical shaft pump configured as described above, the water flows along the inner surface of the vertical wall 5 of the arc-shaped channel 11 and interferes with the tongue 10 in one direction (same as the rotation direction of the pump impeller). Direction), spirally rises along the frusto-conical ridge 9 while being swirled, and is sucked into the vertical shaft pump 1 from the suction port 2 through the suction hole 3, so that a sharp change in direction upward is avoided. The loss in the suction hole 3 can be reduced. In addition, since there is no flow in the reverse direction on the back side of the second center line C2, the loss before being sucked into the suction hole 3 is also reduced. Furthermore, since the cross-sectional area of the arc-shaped flow path 11 is reduced steplessly, the flow velocity here gradually increases, and it is possible to avoid an increase in flow clearance and loss caused by a sudden change in the flow velocity. In addition, since water can be almost uniformly sucked from the entire circumference of the suction port 2 and the suction hole 3, the imbalance of the suction is eliminated, and the generation of the "stagnation portion" is suppressed and the generation of the vortex in the water is suppressed. can do. Furthermore, since the flow velocity can be increased by reducing the width of the suction channel, the size of the suction channel can be reduced.

As a result of intensive studies based on the suction channel of the vertical shaft pump described in the above-mentioned Japanese Patent Application Laid-Open No. Hei 8-109893, the applicant of the present invention has found that
Is varied within a predetermined range and the bottom 8 of the arc-shaped channel 11 is devised to reduce the loss at the suction hole 3 and the loss before being sucked into the suction hole 3, respectively. The effect of eliminating the imbalance of suction by sucking water substantially uniformly from the entire circumference of the suction hole 3, the effect of suppressing the occurrence of underwater vortices by suppressing the generation of "stagnation portions", and the downsizing of the suction channel. We have developed a suction pump for a vertical shaft pump that can achieve the desired effects.

[0010]

In the suction channel of the conventional vertical shaft pump shown in FIGS. 4 to 6, since the flow is rapidly changed in the upward direction, the flow in the suction hole is disturbed and the loss is large. Become. Further, the loss at the suction hole is significantly increased by reducing the width of the suction channel and increasing the flow velocity, so that the reduction of the width of the channel is limited. On the other hand, in the suction channel of the conventional vertical shaft pump shown in FIG. 7, since the degree of the direction change is gentle, the turbulence of the flow in the suction hole is reduced and the loss is reduced. However, reverse flows occur on the back side of the second center line, and they collide with each other, so that a relatively large loss occurs before being sucked into the suction hole 3. In addition, in both cases, the suction state of the suction holes is uneven in the circumferential direction, and the suction performance of the vertical shaft pump is reduced. Further, a "stagnation portion" having an extremely slow flow is generated deeper than the second center line, and the underwater vortex is easily generated here. The generated underwater vortex is sucked into the suction hole and the suction port, and the vertical shaft pump is formed. , Abnormal vibration and noise are generated in the vertical pump. Therefore, the present invention reduces the loss at the suction hole and the loss before being sucked into the suction hole, respectively,
By eliminating water imbalance by sucking water almost uniformly from the entire circumference of the suction hole, it is possible to suppress the occurrence of underwater vortices by suppressing the generation of "stagnation parts" and to make the suction channel compact. It is an object of the present invention to provide a suction pump for a vertical shaft pump.

[0011]

According to a first aspect of the present invention, there is provided a vertical pump having a closed water passage having a closed section having a ceiling, a bottom and both side walls. Extending in the flow direction, a vertical suction hole communicating with the suction port of the vertical shaft pump is formed in the ceiling portion, and a small-diameter frusto-conical raised portion is erected on the bottom portion facing the suction hole, A ceiling wall, a bottom wall, and an upright wall continuous to the side walls on both sides are provided deeper than a second center line orthogonal to a first center line extending through the center of the suction hole and the protruding portion and extending in the flow direction of water, A tongue is formed in which the upstream end of the standing wall and the downstream end of the one side wall in one region of the first center line bulge in an arc shape toward the first center line and join at the tip. And the tip of the tongue from the upstream end of the standing wall in the other area of the first center line. The radius of curvature of the inner surface of the upright wall is continuously reduced gradually from the upstream end to the front end, and is formed between the frusto-conical raised portion and the upright wall at a position deeper than the second center line. In a suction channel of a vertical shaft pump in which the cross-sectional area of the arc-shaped flow path is reduced steplessly, the tip of the tongue portion is located near the first center line on the upstream side of the second center line or more of the suction hole. It is characterized in that it is set at an arbitrary position within a range of about 90 ° up to the second center line. The suction channel of the vertical shaft pump according to the second aspect of the present invention may be configured such that the bottom of the arc-shaped channel is inclined with an upward gradient from the upstream end of the vertical wall in the other area to the tip of the tongue. It is characterized by. Furthermore, in the suction water channel of the vertical shaft pump according to the third aspect of the invention, the vertical cross-sectional shape of the lower end inlet of the vertical suction hole communicating with the suction port of the vertical shaft pump is formed in an arc shape, and the arc surface is The relationship between the radius of curvature R and the inner diameter D of the suction port is set to R ≧ D / 2.

According to the first aspect of the present invention, the tip of the tongue is set at about 90 ° from the vicinity of the first center line to the second center line on the upstream side of the second center line of the suction hole. By setting it at an arbitrary position within the range, the flow of water rises while pre-swinging in one direction while interfering with the tongue along the inner surface of the vertical wall, and is drawn into the vertical shaft pump from the suction port through the suction hole Therefore, a sharp change in direction upward can be avoided, and loss in the suction hole can be reduced. In addition, since water can be sucked evenly from substantially the entire circumference of the suction hole, imbalance in suction can be eliminated and stagnation can be suppressed. In particular, by setting the tip of the tongue at any position except on the first center line within 45 ° from the first center line to the second center line, the flow of water sharply moves upward. The effect of avoiding the conversion and reducing the loss in the suction hole is increased. On the other hand, by setting the tip of the tongue at any position within a range of 90 ° from the position exceeding 45 ° to the second centerline, any position except the first centerline within 45 ° is set. As compared with the case where the tip of the tongue is set at the position, the amount of suction from the upstream side of the second center line in the suction hole is increased, and the amount of water circulating deeper than the second center line is reduced. Less. For this reason, the suction state of the suction hole is slightly uneven in the circumferential direction, and the suction performance of the vertical shaft pump is degraded. However, there is a possibility that underwater vortices are easily generated here, but an effect that can be expected to be considerably improved is obtained as compared with the suction channel of the conventional vertical shaft pump shown in FIG. According to the second aspect of the present invention, the bottom of the arc-shaped flow path is inclined with an upward slope from the upstream end of the standing wall in the other area to the tip of the tongue, so that the flow of water rapidly rises upward. Direction change can be suppressed more effectively. According to the third aspect of the present invention, the flow of water that turns upward while pre-swirling can be smoothly introduced into the suction hole without colliding with the inlet at the lower end of the suction hole.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional plan view of a suction channel to which the present invention is applied, and FIG. 2 is a vertical sectional side view taken along line AA of FIG. The same or corresponding parts as those in the conventional example described with reference to FIGS. 4 to 7 are denoted by the same reference numerals, and detailed description is omitted. In FIG. 1 and FIG.
0A is the first on the upstream side of the second center line C2 of the suction hole 3 or more.
From the center line C1 to the second center line C2 of θ = 45
゜, and the bottom 8 of the arc-shaped channel 11 is the upstream end of the standing wall 5 in the other area of the first center line C1, that is, the standing wall 5 on the second center line C2 and the other end. Of the tongue 10 from the boundary a with the side wall 7B.

A sectional shape of an inlet at a lower end of the suction hole 3;
That is, the cross-sectional shape of the ceiling 6 and the corner 3A of the suction hole 3 is formed in an arc shape, and the relationship between the radius of curvature R and the inside diameter D of the suction hole 3 is set to R ≧ D / 2.

With such a configuration, the flow of water interferes with the tongue portion 10 along the inner surface of the upright wall 5 and pre-turns in one direction (the same direction as the rotation direction of the pump impeller) to form a truncated cone. Since it rises spirally along the ridge 9 and passes through the suction hole 3 and is sucked into the vertical shaft pump 1 from the suction port 2, it is possible to avoid an abrupt upward direction change and reduce the loss in the suction hole 3. Therefore, it is possible to increase the flow velocity by reducing the width of the suction channel, thereby making the suction channel compact and reducing its construction cost. Also, the second center line C
Since there is no flow in the reverse direction on the back side from 2, the loss before being sucked into the suction hole 3 is also reduced. Further, since the bottom 8 of the arc-shaped flow path 11 is inclined upward from the boundary between the standing wall 5 on the second center line C2 and the other side wall 7B to the tip 10A of the tongue 10, the water is Abrupt upward turning of the flow can be avoided more effectively, which can contribute to reducing the loss in the suction hole 3.

Moreover, the cross-sectional shape of the ceiling 6 and the corner 3A of the suction hole 3 is formed in an arc shape, and the curvature radius R and the suction hole 3 are determined.
Is set to R ≧ D / 2, the flow of water that turns upward while pre-swirling in one direction does not collide with the corner 3A and smoothly flows into the suction hole 3. be introduced. That is, in the corner 3A where the relationship between the curvature radius R and the inner diameter D of the suction hole 3 is set to R <D / 2, the flow of water that turns upward while pre-turning in one direction is the corner 3A. It has been confirmed by an experiment that, although the collision occurs, reflection and turbulence of the flow occur, but by setting the relationship of R ≧ D / 2, the gas is smoothly introduced into the suction hole 3 without collision. In this way, the suction holes 3
, The loss in the suction hole 3 can be further reduced. Furthermore, the suction hole 3
The water can be sucked evenly from almost the entire circumference, eliminating the imbalance of suction and the stagnation section
Can be suppressed.

By setting the tip 10A of the tongue 10 at an arbitrary position from the first center line C1 to the second center line C2 except on the first center line C1 within θ = 45 °. ,
(A configuration in which the tip 10A of the tongue 10 is set on the first center line C1 is shown in FIG. 8). The effect of reducing the loss increases.

On the other hand, an arbitrary position within a range of 90 ° from a position exceeding θ = 45 ° to a position on the second center line C2, for example, as shown in FIG. Part 1
By setting the tip 10A of the tongue 10 at an arbitrary position except on the first center line C1 within 45 °,
0A, the second in the suction hole 3
, The amount of suction from the region on the upstream side of the center line increases, and the amount of water flowing to the back side from the second center line C2 decreases. For this reason, the suction state of the suction hole 3 is slightly uneven in the circumferential direction, and the suction performance of the vertical shaft pump 1 is reduced, and the flow is slower in the depth direction than the second center line C2. Although the “stagnation portion” is likely to be generated and there is a possibility that the underwater vortex is easily generated here, FIG.
As compared with the conventional suction pump of the vertical pump shown in FIG.

That is, the front end 10A of the tongue 10 is located on the upstream side of the second center line C2 of the suction hole 3 above the first center line C2.
It can be said that it is desirable to set 0 ≦ θ ≦ 45 ° within a range of about 90 ° from around 1 to on the second center line C2.

[0020]

As described above, according to the present invention, the loss at the suction hole and the loss before suction into the suction hole can be reduced. This makes it possible to reduce the size of the suction channel and reduce construction costs. In addition, by sucking water substantially uniformly from the entire circumference of the suction hole, imbalance of suction can be eliminated, and adverse effects on the vertical shaft pump can be avoided. Furthermore, since the generation of the "stagnation portion" can be suppressed and the generation of the underwater vortex can be suppressed, the occurrence of the inconvenience of the underwater vortex being sucked into the vertical pump can be avoided, and the occurrence of abnormal vibration and noise can also be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional plan view of a suction channel to which an embodiment of the present invention is applied.

FIG. 2 is a vertical sectional side view taken along line AA of FIG. 1;

FIG. 3 is a cross-sectional plan view of a suction channel to which another embodiment of the present invention is applied.

FIG. 4 is a cross-sectional plan view of the first conventional example.

FIG. 5 is a vertical sectional side view taken along line BB of FIG. 4;

FIG. 6 is a vertical sectional front view taken along line CC of FIG. 4;

FIG. 7 is a cross-sectional plan view showing a second conventional example.

FIG. 8 is a cross-sectional plan view of a comparative example.

FIG. 9 is a vertical sectional side view taken along line DD of FIG. 8;

[Explanation of symbols]

 Reference Signs List 1 vertical shaft pump 2 vertical shaft pump suction port 3 suction hole 5 vertical wall 6 ceiling 7A one side wall 7B other side wall 8 bottom 9 truncated conical ridge 10 tongue 10A tip of tongue C1 first center line C2 Second centerline P Suction port and center of suction hole

Claims (3)

[Claims] 1. A closed cross-sectional structure having a ceiling, a bottom, and both side walls, extends in the water flow direction, and a vertical suction hole communicating with a suction port of a vertical pump is formed in the ceiling. A small-diameter frusto-conical ridge is erected at the bottom opposite the suction hole and extends through the center of the suction hole and the ridge to a second center orthogonal to a first center line extending in the flow direction of water. A standing wall continuous with the ceiling, the bottom, and both side walls is provided at a position deeper than a line, and the upstream end of the standing wall and the downstream end of the one side wall of the first center line in one region are set to the first position.
A tongue bulging in an arc and merging at the tip is formed on the center line side of the tongue, and the upright wall of the upright wall extending from the upstream end of the upright wall in the other region of the first center line to the tip of the tongue portion is formed. The radius of curvature of the inner surface is set continuously and gradually smaller from the upstream end to the front end, and the arc-shaped flow path formed between the frusto-conical ridge and the standing wall deeper than the second center line. In a suction channel of a vertical shaft pump whose cross-sectional area is reduced steplessly, the tip of the tongue is located on the second center line from near the first center line on the upstream side of the second center line of the suction hole or more. Characterized by being set at an arbitrary position within a range of about 90 ° to the vertical pump. 2. The vertical shaft pump according to claim 1, wherein the bottom of the arc-shaped flow path is inclined upward from the upstream end of the standing wall in the other area to the tip of the tongue. Suction channel. 3. A vertical cross-sectional shape of an inlet at a lower end portion of a vertical suction hole communicating with a suction port of the vertical shaft pump is formed in an arc surface, and a relationship between a radius of curvature R of the arc surface and an inner diameter D of the suction port. Is set to R ≧ D / 2, the suction channel of the vertical pump according to claim 1, wherein