JPH09209995A - Suction water passage of drainage pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the generation of a surface eddy near both side surfaces of a closed section part in a suction water passage and the generation of an air suction eddy, prevent the suck in of an air to a drainage pump, avoid the generation of vibration and noise, reduce the residual water amount of a pump suction water tank by lowering the lowest water level capable of pumping up to a low level and also miniaturize the pump suction water tank by increasing a flow speed. SOLUTION: The suction water passage 2 from a suction water tank to a drainage pump has a closed section part 7 surrounded by a bottom surface 3, both side surfaces 4, 5 and a ceiling 6. The ceiling 6B on the upperstream side of the closed section part 7 is formed in an uniform section shape provided with a straight line orthogonally crossing to a flow F and a slant surface 8 for restraining the generation of a surface eddy and an air suction eddy following to this by retreating from the upperstream side of the suction water passage 2 toward the downstream side in the width direction both sides of this straight line.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a suction water passage of a drainage pump.

[0002]

2. Description of the Related Art As shown in FIGS. 10 and 11, drainage having a closed cross section 7 surrounded by a bottom surface 3, both side surfaces 4, 5 and a ceiling 6 in a suction water passage 2 from a water absorption tank 1 to a drainage pump P. In the suction water passage of the pump, the ceiling 6 of the closed cross section 7 includes a lower ceiling 6A near the suction port of the drainage pump P and an upper ceiling 6 near the water absorption tank 1 connected to the ceiling 6A.
B, and the ceiling 6B on the upstream side has a vertical sectional shape inclined downward from the upstream side to the downstream side, and the sectional shape at the position P1 of the ceiling 6B is as shown in FIG.
As shown in FIG. 5, it is formed by a straight line orthogonal to the flow F.

By the way, the velocity distribution on the projection plane of the water flowing through the suction water passage 2 is generally high (fast) in the widthwise central portion of the suction water passage 2 as shown by the arrow group f, and both side surfaces of the suction water passage 2 are shown. The characteristic becomes lower (slower) as it approaches 4,5. If the cross-sectional shape of the ceiling 6B is formed by a straight line orthogonal to the flow F, even though water flows with a velocity distribution having such characteristics, the flow in the high-speed region at the center in the width direction and the flow in the vicinity thereof. Is P on the ceiling 6B in FIG.
By colliding with the 1st position, as shown by the arrow X in FIG. 12, it flows downward along the ceiling 6B and flows toward both side faces 4 and 5, and both side faces 4 and 4 at the P2 position in FIG.
In the vicinity of 5, the backflow occurs along both side surfaces 4 and 5 as indicated by the arrow X in FIG. 13, and the reverse flow portion and the forward flow on the surface in the low speed region on both sides in the width direction indicated by the arrow X1 and in the vicinity thereof. The parts interfere with each other, and a surface vortex indicated by x in FIGS. 13 and 14 is generated. The generation of such surface vortices x becomes more remarkable as the flow velocity of water flowing down the suction water passage 2 becomes higher, and finally x1 in FIG.
As shown by, there is a risk that it will develop into an air suction vortex that entrains air into the drainage pump P.

On the other hand, even if the surface vortex x is generated in the vicinity of both side surfaces 4 and 5 of the closed cross section 7, if the water level in the water absorption tank 1 is relatively high, the air suction vortex x1 does not develop and the drainage pump. It does not adversely affect P. However, when the surface vortex x is generated in the low water state, the position where the surface vortex x is generated is P in FIG.
2 will be moved to the vicinity of both side surfaces 4 and 5 on the downstream side of 2 and air will be sucked into the drainage pump P (air suction vortex x
There is a fear that the suction pumping of air causes vibration and noise in the drainage pump P. Therefore, the lowest level of water that can be pumped must be set to a relatively high level, and there is a drawback that the amount of residual water in the pump water absorption tank 1 increases accordingly.

On the other hand, the pump water absorption tank 1 of this type can be downsized by increasing the flow velocity of water, and the construction cost of the pump water absorption tank 1 can be reduced. However, when the flow velocity is increased, surface vortices x are generated, which easily develop into air suction vortices x1, which hinders downsizing of the water absorption tank 1.

[0006]

That is, in the suction water passage of the conventional drainage pump, in the closed cross-section portion having the ceiling inclined downward from the upstream side to the downstream side, the horizontal cross-sectional shape of the ceiling is water. Since it is formed by a straight line that is orthogonal to the flow of water, surface vortices are generated near both sides of the closed cross section, and when surface vortices are generated when the water level in the pump absorption tank is low, it becomes an air suction vortex and becomes a drainage pump. There is a risk that air will be sucked into the drain pump, and vibration and noise will occur in the drain pump. Therefore, the lowest water level that can be pumped must be set to a relatively high level, and the amount of residual water in the pump water absorption tank increases accordingly. Further, when the flow velocity is increased, surface vortices are generated, which easily develop into air suction vortices, which hinders downsizing of the water absorption tank. Therefore, the present invention suppresses the generation of surface vortices in the vicinity of both side surfaces of the closed cross section in the suction water passage, and suppresses the generation of air suction vortices,
Preventing air from being sucked into the drainage pump, avoiding vibration and noise, lowering the lowest pumpable water level to a low level, and reducing the amount of water remaining in the pump water absorption tank.
It is an object of the present invention to provide a suction water passage for a drainage pump, which can increase the flow velocity to reduce the size of the pump water absorption tank.

[0007]

In order to achieve the above object, the invention according to claim 1 has a closed cross section surrounded by a bottom surface, both side surfaces and a ceiling in a suction water passage from a water absorption tank to a drainage pump. However, in the suction water channel of the pump in which the ceiling of this closed cross section is inclined downward from the upstream side to the downstream side, the air retreats from the upstream side to the downstream side of the suction water channel on both sides in the width direction of the ceiling. It is characterized in that an inclined surface for suppressing the generation of suction vortices is formed. Further, the invention according to claim 2 has a closed cross section surrounded by a bottom surface, both side surfaces and a ceiling in the suction water passage from the water absorption tank to the drainage pump, and the ceiling of the closed cross section is arranged from the upstream side to the downstream side. In the suction water channel of the pump that is inclined downward, arc-shaped surfaces that retreat from the upstream side to the downstream side of the suction water channel to suppress the generation of air suction vortices are formed on both sides in the width direction of the ceiling. It is characterized by. Further, in the invention according to claim 3, the dimension in the width direction from the upstream side starting point of the suction water channel on the inclined surface and the arc surface to the both side surfaces is within a range of 1/2 to 1/15 of the entire width of the suction water channel. It is characterized by being set. According to the invention of claim 1, the flow in the surface in the high speed region in the widthwise center and in the vicinity thereof flows downward along the ceiling after colliding with the ceiling of the closed cross section, and toward the both side surfaces. In the vicinity of both side surfaces downstream of the flow and collision position, the current flows toward the downstream side along the inclined surface. In other words, the flow that interferes in the opposite direction to the forward flow on the surface in the low speed region on both sides in the width direction and in the vicinity thereof will not occur, so that the generation of surface vortices in the vicinity of both side surfaces will be suppressed and air suction vortices will be generated. Can be suppressed. According to the second aspect of the present invention, the flow of the surface in the high speed region in the widthwise central portion and the flow in the vicinity thereof collide with the ceiling of the closed cross section and then flow downward along the ceiling, and on both side surfaces. In the vicinity of both side surfaces downstream of the collision position, the current flows toward the downstream side along the arc surface. In other words, the flow that interferes in the opposite direction to the forward flow on the surface in the low speed region on both sides in the width direction and in the vicinity thereof will not occur, so that the generation of surface vortices in the vicinity of both side surfaces will be suppressed and air suction vortices will be generated. Can be suppressed. Further, according to the invention described in claim 3,
Effective generation of surface vortices by setting the dimension in the width direction from the upstream side starting point of the suction water channel on the inclined surface and the arc surface to the range of 1/2 to 1/15 of the total width of the suction water channel. It is possible to suppress the occurrence of air suction vortices and to avoid fluctuations in the velocity distribution in the width direction of the suction water channel, and to suck up water from the entire circumference of the suction port of the drainage pump in the circumferential direction. To

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. 1 is a vertical sectional side view of a suction water passage of a drainage pump to which the invention according to claim 1 is applied, and FIG.
FIG. 4 is a sectional view taken along line AA of FIG. In addition, FIG.
The same or corresponding parts as those of the conventional example described in 5 will be described with the same reference numerals. 1 and 2, the suction water passage of the drainage pump has a closed cross-section portion 7 surrounded by a bottom surface 3, both side surfaces 4, 5 and a ceiling 6 in a suction water passage 2 from the water absorption tank 1 to the drainage pump P. The ceiling 6 of the closed section 7
Comprises a low ceiling 6A extending substantially horizontally on the downstream side near the suction port of the drainage pump P, and an upstream ceiling 6B near the water absorption tank 1 connected to this ceiling 6A. The upstream ceiling 6B
Has a vertical cross-sectional shape inclined downward from the upstream side to the downstream side. The inclination angle θ1 of the ceiling 6B is
It is set in the range of 45 ° or more and less than 90 °.

The ceiling 6B on the upstream side, as shown in FIG.
A straight line orthogonal to the flow F and inclined surfaces 8 formed on both sides in the width direction of this straight line, that is, an inclined surface 8 that retreats from the upstream side to the downstream side of the suction water passage 2 to suppress the generation of air suction vortices. With a uniform cross-sectional shape. The intersection angle θ2 between the inclined surface 8 and the side surfaces 4 and 5 of the suction water passage 2 is 15
It is set in the range of 60 to 60 degrees, and in the illustrated example, it is set to 45 degrees. In addition, the dimension w in the width direction from the upstream side start point p1 of the suction water channel 2 on the inclined surface 8 to both side surfaces 4 and 5 is set to 1/10 of the total width W of the suction water channel 2.

With such a structure, the flow in the high speed region at the center in the width direction of the suction water passage 2 and the flow in the vicinity thereof collide with the position P1 of the ceiling 6B of the closed cross section 7 in FIG.
As shown by the arrow X in FIG. 3, it flows downward along the ceiling 6B and toward both side surfaces 4 and 5, and in the vicinity of the side surfaces 4 and 5 at the position P2 in FIG. As shown by, the current flows toward the downstream side along the inclined surface 8.
In other words, a flow that interferes in the opposite direction with the forward flow X1 on the surface in the low speed region on both sides in the width direction and in the vicinity thereof does not occur. It is possible to suppress the generation of suction vortices. As a result, it is possible to prevent air from being sucked into the drainage pump P, avoid generation of vibrations and noise, reduce the lowest water level that can be pumped to a low level, and reduce the amount of water remaining in the pump water absorption tank 1, and the flow velocity. Therefore, the pump water absorption tank 1 can be downsized.

The dimension w in the width direction from the upstream side start point p1 of the suction water passage 2 on the inclined surface 8 to both side surfaces 4 and 5 is not set to only 1/10 of the total width W of the suction water passage 2 described above. Not from 1/2 (see FIG. 5) to 1/15 of full width W
It is sufficient if it is within the range. That is, the dimension w in the width direction is 1 /
If it is less than 15, the effect of suppressing the generation of surface vortices and the accompanying air suction vortices is small.
Is asymmetric in the width direction of the suction water passage 2, the velocity distribution in the width direction fluctuates, and the function of sucking water evenly from the entire circumference in the circumferential direction of the suction port in the drainage pump P is reduced. It will reduce efficiency. Further, the intersection angle θ2 between the inclined surface 8 and both side surfaces 4 and 5 of the suction water passage 2 is 1
It has been confirmed by experiments that when the angle is smaller than 5 ° or exceeds 60 °, the effect of suppressing the generation of surface vortices and the accompanying air suction vortices decreases.

FIG. 6 is a vertical sectional side view of a suction water passage of a drainage pump to which the invention according to claim 2 is applied, and FIG. 7 is a sectional view taken along line D-D of FIG. The same or corresponding parts as those of the invention according to claim 1 are designated by the same reference numerals, and detailed description thereof will be omitted. 6 and 7, the ceiling 6B on the upstream side
Is a straight line orthogonal to the flow F and arcuate surfaces 9 formed on both sides of this straight line in the width direction, that is, an arc that retreats from the upstream side to the downstream side of the suction water passage 2 to suppress the generation of air suction vortices. It has a uniform cross-sectional shape with a surface 9. The starting point p1 on the upstream side of the circular arc surface 9 and both side surfaces 4, 5 of the suction water passage 2
The intersection angle θ2 between the straight line 10 connecting the intersection point p2 with and the side surfaces 4 and 5 is set in the range of 15 ° to 60 °, and is set to 45 ° in the illustrated example. In addition, the dimension w in the width direction from the upstream side start point p1 of the suction water passage 2 on the arc surface 8 to both side surfaces 4 and 5 is set to 1/10 of the total width W of the suction water passage 2.

With such a structure, the flow in the surface of the high speed region in the central portion in the width direction of the suction water passage 2 and the flow in the vicinity thereof collide with the position P1 of the ceiling 6B of the closed cross section 7 in FIG.
As shown by the arrow X in FIG. 7, it flows downward along the ceiling 6B and toward both side surfaces 4 and 5, and in the vicinity of the side surfaces 4 and 5 at the position P2 in FIG. As shown by, the current flows toward the downstream side along the arc slope 9. In other words, a flow that interferes in the opposite direction with the forward flow X1 on the surface in the low speed region on both sides in the width direction and in the vicinity thereof does not occur. It is possible to suppress the generation of suction vortices. As a result, it is possible to prevent air from being sucked into the drainage pump P, avoid generation of vibrations and noise, reduce the lowest water level that can be pumped to a low level, and reduce the amount of water remaining in the pump water absorption tank 1, and the flow velocity. Pump water tank 1
It is possible to reduce the size.

The dimension w in the width direction from the upstream side start point p1 of the suction water passage 2 on the arc surface 9 to both side surfaces 4 and 5 is set only to 1/10 of the total width W of the suction water passage 2 described above. Not from 1/2 (see FIG. 9) to 1/15 of full width W
It is sufficient if it is within the range. That is, the dimension w in the width direction is 1 /
If it is less than 15, the effect of suppressing the generation of surface vortices and the resulting air suction vortices is small.
Is asymmetric in the width direction of the suction water passage 2, the velocity distribution in the width direction fluctuates, and the function of sucking water evenly from the entire circumference in the circumferential direction of the suction port in the drainage pump P is reduced. It will reduce efficiency. In addition, the starting point p1 on the upstream side of the arc surface 9 and both side surfaces 4, 5 of the suction water passage 2
If the angle of intersection θ2 between the straight line 10 connecting the intersection point p2 with and the side surfaces 4 and 5 is smaller than 15 ° or exceeds 60 °, the effect of suppressing the generation of surface vortices and the accompanying air suction vortex is reduced. It has been confirmed by experiments that this is done.

[0015]

As described above, according to the invention of claim 1, in the vicinity of both side surfaces of the closed cross section of the suction water passage,
The flow in the high-speed region in the widthwise center and in the vicinity thereof flows toward the downstream side along the inclined surface, and interferes in the opposite direction with the forward flow in the low-speed region on both sides in the widthwise direction and in the vicinity. Since it does not occur, it is possible to suppress the generation of surface vortices in the vicinity of both sides and suppress the generation of air suction vortices, prevent the suction of air into the drain pump, and prevent the generation of vibration and noise. Avoiding this, it is possible to reduce the minimum pumpable water level to a low level to reduce the amount of residual water in the pump water absorption tank, and to increase the flow velocity to reduce the size of the pump water absorption tank. Further, in the invention according to claim 2, in the vicinity of both side surfaces of the closed cross-section portion in the suction water passage, the flow in the surface of the high speed region in the widthwise central portion and in the vicinity thereof flows toward the downstream side along the arc surface, Since it does not interfere in the opposite direction with the forward flow on the surface in the low speed region on both sides in the width direction and in the vicinity thereof, it suppresses the generation of surface vortices near both sides and suppresses the generation of air suction vortices. It prevents the intake of air into the drainage pump, avoids vibration and noise, lowers the lowest water level that can be pumped to a low level, reduces the amount of water remaining in the pump water absorption tank, and increases the flow velocity. It is possible to reduce the size of the pump water absorption tank. Furthermore, the invention according to claim 3 enhances the effect of suppressing the generation of surface vortices and air suction vortices, and avoids fluctuations in the velocity distribution in the width direction, so that the suction ports of the drainage pump are evenly distributed from the entire circumference in the circumferential direction. The function of sucking up water can be maintained, and the reduction in pump efficiency can be avoided.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing an embodiment of the invention according to claim 1.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a sectional view taken along line CC of FIG. 1;

FIG. 5 is a view corresponding to FIG. 4 showing another embodiment of the inclined surface.

FIG. 6 is a vertical sectional side view showing an embodiment of the invention according to claim 2;

FIG. 7 is a sectional view taken along line DD of FIG. 6;

FIG. 8 is a sectional view taken along line EE of FIG. 6;

9 is a view corresponding to FIG. 6 showing another embodiment of the arc surface.

FIG. 10 is a vertical sectional side view showing a conventional pump water absorption tank.

FIG. 11 is a sectional view taken along line GG of FIG. 10;

12 is a sectional view taken along line HH of FIG.

13 is a cross-sectional view taken along the line I-I of FIG.

FIG. 14 is a vertical cross-sectional side view showing a generation state of surface vortices.

FIG. 15 is a vertical cross-sectional side view showing how air suction vortices are generated.

[Explanation of symbols]

 1 Water absorption tank 2 Suction water channel 3 Bottom of closed cross section 4 One side of closed cross section 5 Other side of closed cross section 6 Ceiling of closed cross section 7 Closed cross section 8 Inclined surface 9 Arc surface P Drain pump x Surface vortex x1 Air Suction vortex

Claims (3)

[Claims] 1. A suction water passage from a water absorption tank to a drainage pump has a closed cross section surrounded by a bottom surface, both side surfaces and a ceiling, and the ceiling of the closed cross section is inclined downward from upstream to downstream. In the suction water passage of the pump, the drainage is characterized in that inclined surfaces are formed on both sides of the ceiling in the width direction to retreat from the upstream side to the downstream side of the suction water passage to suppress the generation of air suction vortices. Pump suction channel. 2. The suction water passage from the water absorption tank to the drainage pump has a closed cross section surrounded by a bottom surface, both side surfaces and a ceiling, and the ceiling of the closed cross section is inclined downward from the upstream side to the downstream side. In the suction water passage of the pump, the drainage characterized in that arc-shaped surfaces are formed on both sides of the ceiling in the width direction to retreat from the upstream side to the downstream side of the suction water passage to suppress the generation of air suction vortices. Pump suction channel. 3. The dimension in the width direction from the upstream side start point of the suction water channel on the inclined surface and the arc surface to the both side surfaces is set within a range of 1/2 to 1/15 of the total width of the suction water channel. The suction water channel of the drainage pump according to claim 1 or 2.