JPH0979198A - Suction waterway of large drainage pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent air from being sucked in a drainage pump even if a water surface largely waves by flowing down water at high speed, and avoid vibration, a noise and occurrence of a pumping cutoff condition by making roughness of a ceiling part in a closed cross-sectional part of a suction waterway of a large drainage pump roughter than roughness of the other surface. SOLUTION: A suction waterway 2 of a large drainage pump P has a closed cross-sectional part 7 surrounded by both side surfaces and the ceiling 6, and roughness of a ceiling 6 part is formed rougher (a roughness factor is set not less than 0.02) than roghtness of a bottom surface 3 and both side surfaces. Therefore, interfacial resistance between the ceiling 6 and water becomes large, and an interface of water can be restrained from being pulled in the drainage pump P side. Therefore, even if a water surface in a water absorbing tank 1 and a suction waterway 2 largely waves by flowing down water at high speed, air can be prevented from being sucked in a drainage pump P, and therefore, inconvenience such as vibration and a noise are generated and a pumping cutoff condition is incurred can be avoided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a suction water channel for a large drainage pump.

[0002]

2. Description of the Related Art As shown in FIG. 3 and FIG.
To the drainage pump P from the bottom surface 3, both side surfaces 4,
In the suction water passage 2 of the large-sized drainage pump having the closed cross-section portion 7 surrounded by 5 and the ceiling 6, the bottom surface 3, the side surfaces 4, 5 and the ceiling 6 of the closed cross-section portion 7 are formed by a normal concrete surface. . By the way, since an ordinary concrete surface has a small roughness coefficient (about 0.015), the bottom surface 3, both side surfaces 4, 5 and the ceiling 6 of the closed cross section 7 and the closed cross section 7 are closed.
It is possible to suppress the interface resistance with the water flowing down to reduce the suction water channel resistance.

However, when the flow velocity of the water flowing down the suction water passage 2 becomes high due to a large amount of drainage operation by the large-scale drainage pump P, the water surface largely fluctuates up and down and becomes wavy.
Even if the water surface is largely wavy, it does not have an adverse effect when the water level in the water absorption tank 1 is relatively high as shown by the solid line in FIG. However, when a large waviness is generated on the water surface in a low water level state as indicated by the phantom line, the interface between the ceiling 6 and the water flowing down the closed cross-section portion 7 is small, so that the water interface is a dashed line. As shown in the drawing, there is a risk that the drain pump P will be drawn into and the air E will be sucked into the drain pump P, and the suction of the air E will cause harmful effects such as vibration and noise in the drain pump P. When the intake amount of the air E is large, there is a possibility that the idling state (pumping off state) may occur. Therefore, the minimum water level that can be pumped must be set to a relatively high level,
As a result, there is a drawback that the amount of residual water in the pump water absorption tank 1 increases.

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, if the flow velocity is increased, the above-mentioned waviness becomes large, which hinders downsizing of the water absorption tank 1.

[0005]

That is, in the suction water passage of the conventional large-sized drainage pump in which the bottom surface, both side surfaces and the ceiling of the closed cross-section portion of the suction water passage are formed by the normal concrete surface, the water flowing down the closed cross-section portion is While the interface resistance between the ceiling and the water can be reduced by suppressing the interface resistance of the water to a small value, the interface between the water and the ceiling is decreased, so that the water interface is drawn into the drain pump side. Therefore, run a large drainage pump with the water level in the pump water absorption tank low,
If the water surface undulates due to high-speed flow of water, there is a risk that air will be sucked into the drainage pump, which will cause vibrations and noise in the drainage pump, and eventually cut off the pumping water. There is a risk of becoming. 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, increasing the flow velocity increases the above-mentioned waviness, which hinders downsizing of the water absorption tank. Therefore, in the invention according to claim 1, the roughness of the ceiling portion of the closed cross-section portion in the suction water channel is made larger than the roughness of the other surface, thereby increasing the interface resistance between the ceiling and water to increase the water interface. The water is prevented from being drawn into the drainage pump side, and the water is allowed to flow down at a high speed to prevent air from being sucked into the drainage pump even if the water surface undulates significantly, thus preventing vibration, noise, and eventually pumping up. Avoiding the occurrence of conditions, lowering the lowest water level that can be pumped to a low level to reduce the amount of residual water in the pump water absorption tank, and increasing the flow velocity to reduce the size of the pump water absorption tank. It is intended to be provided. Further, in the invention according to claim 2, the roughness can be imparted to the ceiling portion enough to prevent the interface of water from being drawn into the drainage pump side.

[0006]

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. In the suction water channel of the large-sized drainage pump, the roughness of the ceiling portion in the closed cross section of the suction water channel is made larger than the roughness of other surfaces. Claim 1
According to the invention described above, the roughness of the ceiling portion in the closed cross section is made larger than the roughness of the bottom surface and both side surfaces of the closed cross section, so that the interface resistance between the ceiling and water is increased and the water interface is It can be restrained from being drawn into the drain pump side.
As a result, it is possible to prevent air from being sucked into the drainage pump even if the water surface undulates by flowing water at a high speed. The invention according to claim 2 is characterized in that the roughness of the ceiling portion of the closed cross section of the suction water channel is set to a roughness coefficient of 0.02 or more. According to the second aspect of the invention, by setting the roughness of the ceiling portion to a roughness coefficient of 0.02 or more, it is possible to reliably prevent the water interface from being drawn into the drainage pump side.

[0007]

Embodiments 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 large-sized drainage pump to which the present invention is applied, and FIG. 2 is a sectional view taken along the line AA of FIG. It should be noted that the same or corresponding portions as the suction water passage of the conventional large-sized drainage pump described with reference to FIGS. 1 and 2, the suction water passage of the large-sized 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 bottom surface 3 and both side surfaces 4 and 5 of the closed cross-section portion 7 are formed by an ordinary concrete surface (coefficient of roughness = about 0.015), and the roughness of the ceiling 6 portion is the bottom surface 3 and both side surfaces 4. , 5 (roughness coefficient = 0.02 or more).

In this way, by making the roughness of the ceiling 6 portion in the closed cross section 7 larger than the roughness of the bottom surface 3 and both side surfaces 4 and 5, the interface resistance between the ceiling 6 and water is increased. It is possible to prevent the water interface from being drawn into the drainage pump P side. As a result, it is possible to prevent air from being sucked into the drainage pump even if the water surface undulates by flowing water at a high speed. Therefore, it is possible to suppress the phenomenon in which the interface of the water is drawn to the drainage pump P side (see the alternate long and short dash line in FIG. 3) even if a large undulation occurs on the water surface in the low water level state shown by the phantom line in FIG. In other words, even if the water surface undulates by flowing water at a high speed, the drainage pump P
To prevent air from being sucked into the pump, avoid vibration and noise, and eventually prevent pumping interruptions, lower the lowest pumpable water level to a low level, and reduce the amount of water remaining in the pump water absorption tank. Therefore, the pump water absorption tank 1 can be downsized.

Moreover, the roughness of the ceiling 6 portion is set to a roughness coefficient of 0.
Since it is set to 02 or more, the water interface is
It is possible to reliably suppress the pulling to the side.
That is, if the roughness of the ceiling 6 portion is less than 0.02, a large waviness occurs on the water surface in the low water level state shown by the phantom line in FIG. 1, and as shown by the alternate long and short dash line in FIG. If the interface of is drawn toward the drainage pump P and the roughness of the ceiling 7 portion is not less than 0.02, even if a large undulation occurs on the water surface in the low water level state shown by the phantom line in FIG. The result that the interface of No. is not drawn to the drainage pump P side is confirmed by the experiment.

[0010]

As described above, according to the first aspect of the present invention, the roughness of the ceiling portion in the closed cross section is made larger than the roughness of the bottom surface and both side surfaces of the closed cross section, so that the ceiling and the water can be removed. It is possible to increase the interface resistance with and to prevent the water interface from being drawn into the drain pump side. This prevents air from being sucked into the drainage pump even when the water surface undulates by allowing water to flow down at a high speed, resulting in vibration and noise, which in turn results in a pumping interruption condition. Can be avoided. As a result, the lowest water level that can be pumped can be lowered to a low level to reduce the amount of residual water in the pump water absorption tank, and the flow velocity can be increased to reduce the size of the pump water absorption tank.
According to a second aspect of the present invention, the roughness of the ceiling portion is set to a roughness coefficient of 0.
By setting it to 02 or more, it is possible to reliably prevent the interface of water from being drawn into the drain pump side.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of the present invention.

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

FIG. 3 is a vertical cross-sectional side view showing a conventional pump water absorption tank.

4 is a sectional view taken along line BB of FIG.

[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 P Pump

Claims (2)

[Claims] 1. In a suction water channel of a large-sized drainage pump having a closed cross section surrounded by a bottom surface, both side surfaces and a ceiling in a suction water channel from a water absorption tank to a drain pump, a ceiling portion at a closed cross section of the suction water channel is rough. Suction channel for large drainage pumps, characterized in that the degree of roughness is greater than the roughness of other surfaces. 2. The suction water channel for a large-sized drainage pump according to claim 1, wherein the roughness of the ceiling portion of the closed cross section of the suction water channel is set to a roughness coefficient of 0.02 or more.