JPH0426717Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention is characterized in that the axial gap between the first impeller attached to the drive shaft and the casing wall in front of the impeller is sufficient for solid matter to pass through. This submersible pump has a large size and has a suction port located at the bottom.

[Prior Art] Submersible pumps, particularly non-obstructive submersible pumps, are suitable for handling sewage and the like containing solid matter and are widely used.

This type of pump is, for example,
The liquid passage between the impeller placed in the pump casing and the inner wall of the casing is kept relatively wide, and solids mixed in the liquid are discharged through this passage. It is configured so that it does not flow to the outlet and block the pump.

In a so-called vertical pump in which the suction port is located below, the impeller rotates on a substantially horizontal plane. In such a submersible pump, when the water level drops and the pump operates in air, when air is sucked in through the suction port, the air gathers in the center of the impeller because air is lighter than water. Once this condition occurs, even if the water level rises again, water will not be pumped up due to the presence of air pockets, resulting in a so-called airlock phenomenon.

In addition, this type of pump has a large gap between the suction port and the impeller that allows solids to pass through, so if the water level is only up to the suction port, water cannot be pumped even if the pump is started, and the water level It is only when the water reaches the impeller that water can be pumped. These disadvantages are all caused by air gathering around the impeller.

For example, Japanese Utility Model Publication No. 58-36872 discloses a technique in which a helical vane device is provided to push water up to the lowest impeller to disturb the equilibrium between water and air, thereby releasing the aerodynamics. However, such technology is not applicable to pumps where the axial gap between the front surface of the impeller and the casing wall is sufficiently large to allow solids to pass through, since the helical vane device obstructs the passage of solids. I can't. Moreover, this spiral wing device does not perform a self-sufficiency function of makeup water.

[Purpose of the invention] Therefore, the purpose of the invention is to make it possible to exhaust the air that collects near the center even if an aerodynamic phenomenon occurs.
To provide a submersible pump capable of performing drainage work even when the water level drops to near zero.

[Structure of the invention] In the invention, a second impeller with a small diameter is provided at the tip of the drive shaft on the suction port side of the first impeller, a pump stand is provided in front of the casing, and the casing and the pump stand are connected. It has a structure in which a passage is formed between the two.

[Operation and effect of the invention] Therefore, if the water level is now lowered to a position slightly higher than the passage between the casing and the pump stand, the water will be sucked in through the suction port and its passage, and the pump will work just like a conventional pump. Demonstrates excellent pump performance.

When the water level further decreases to below the passage, a portion of the water sucked in from the suction port flows out through the passage, but returns to the suction port from the bottom of the pump stand, making up for makeup water. can fulfill the role of That is, the passage serves as a passage for make-up water and is filled with make-up water, so that no air is sucked in from this passage, and the air inside the casing is discharged to the outside together with the make-up water.

Therefore, even when starting at a water level below the passage, the effect of the make-up water described above occurs, and as a result, the negative pressure inside the casing gradually increases, and the water from the suction port to the second
Since the water is sucked up by the impeller, drainage work can be carried out until the water level is essentially close to zero.

As described above, according to the present invention, the second impeller;
Due to the combination of the pump stand and the passage between the casing and the pump stand, even if there is air in the casing and an aerodynamic condition occurs, the air and water can be replaced, pumping activity can be continued, and the water level can be reduced. Pumping action can be performed until the value is close to zero. That is, the second impeller functions to return make-up water to the passage between the pump stand and the casing, and exhausts the air inside the casing to the outside through the passage, separating air and water, and removing the negative air inside the casing. It maintains pressure.

[Examples] Examples of the present invention will be described below with reference to the drawings.

The figure is a cross-sectional side view of a submersible pump embodying the present invention, in which a pump casing 1 is arranged with the suction port 2 facing downward, and a first impeller 3 is inside the casing 1 and is rotated by a motor (not shown). Drive shaft 4
installed on. A first passage 5 is formed between the inner wall surface of the casing 1 and the front surface of the first impeller 3, and water flowing in from the suction port 2 is pressurized by the first impeller 3 and discharged. It is adapted to be pushed out to the outlet 6. On the bottom surface of pump casing 1,
A pump stand 9 is attached via a spacer 7. Due to the presence of this spacer 7, the casing 1
A second passage 8 having a diameter of, for example, about 5 mm is formed between the lower surface of the pump and the pump stand 9.

Furthermore, a second impeller 1 is installed at the tip of the drive shaft 4.
0 is attached, and this second impeller 10 is provided with axial flow or diagonal flow blades. This second impeller 10 is provided so as to be located within the suction port 2. Therefore, the second impeller 10
A gap 11 is also formed between the outer periphery of the suction port 2 and the suction port 2 . Further below the pump stand 9 is a rectifying plate 12.
is provided to prevent foreign matter from being sucked into the suction port 2. During normal operation, water passes through the gap between the baffle plate 12 and the pump stand 9 and the passage 8 between the pump stand 9 and the casing 1 due to the rotation of the first and second impellers. The liquid is sucked into the casing 1 through the suction port 2, and then discharged from the discharge port 6. However, if the water level is now slightly lower than the first impeller 3, the first impeller 3
Air gathers in the center of the impeller 3, causing an air lock phenomenon.

At this time, the water level has reached suction port 2, so
Pumping work is continued by the second impeller 10,
Most of the flow is directed towards the first impeller 3, and some of the flow flows out from the passage 8. The water heading towards the first impeller 3 flows into an air pocket (negative pressure section) formed at the center of the first impeller 3, and part of the air flows into the center of the second impeller 10. is pushed to the negative pressure section of the Further, a part of the air is discharged from the discharge port 6 together with water. The air is returned to the central negative pressure section of the second impeller 10 and discharged through the air passage 8. As a result, the first impeller 3 is filled with water and the air lock is eliminated.

Next, when the water level decreases and the passage 5 becomes exposed, the negative pressure generated by the first impeller 3 becomes stronger. Therefore, the passage 8 of the second impeller 10
The amount of water discharged into the passageway decreases, water accumulates in the passage, and no air is sucked in or water is discharged from there. Therefore, since a balanced state is achieved, water is sucked from the gap at the bottom, making it possible to lower the water level to the lowest water level.

As a result, if the water level is such that the second impeller 10 is submerged, the water level can be reliably drained to near zero without replenishing (priming) water into the casing 1. In addition, even if water accumulates in a part of the piping or the sunny hose breaks, resulting in a fully closed condition, the pressure can be immediately restored, making it possible to pump water.

[Summary] As described above, the present invention provides a submersible pump in which a small-diameter second impeller is provided at the tip of the drive shaft of the pump impeller, and this second impeller is connected to the suction port that opens on the lower surface of the pump casing 1. At the same time, a passage was formed using the casing and the pump stand in the radial direction of the second impeller, so even if the water level drops slightly from the position of the first impeller, This makes it possible to prevent air locks from occurring, and also allows air to be exhausted from the passage between the casing and the pump stand when the water level drops. Furthermore, the second impeller allows suction work to be performed even at a lower water level than before.

[Brief explanation of the drawing]

The drawing is a sectional side view showing an embodiment of the present invention. 1...Casing, 2...Suction port, 3...First
4... Drive shaft, 5... Passage, 6... Discharge port, 8... Passage, 9... Pump stand, 10... Second impeller.

Claims (1)

[Scope of utility model registration request] A submersible pump in which the axial gap between the first impeller attached to the drive shaft and the casing wall in front of the impeller is large enough for solid matter to pass through, and the suction port is located below. A second impeller with a small diameter is provided at the tip of the drive shaft on the suction port side of the first impeller, and a pump stand is provided in front of the casing, and a passage is formed between the casing and the pump stand. A submersible pump characterized by: