JPH03217694A - Casing with airlock phenomenon preventive device of volute pump - Google Patents

Abstract

PURPOSE:To eliminate an airlock phenomenon in a volute chamber and to maintain the pumping-up and pumping-out capacity by providing a discharge port at the central upper side of the casing of a pump, and an air vent hole at the foot of the starting position of the volute winding. CONSTITUTION:A discharge port 7 is provided at the central upper side of the casing 1 of a volute pump. At the foot of the starting position 9 of the volute winding, an air vent hole 12 from a volute chamber 8 to the discharge port 7 is provided. The air sucked together with dirty muddy water from a suction port is discharged from the discharge port 7 at the center of the casing 1 without accumulating at the upper part of the volute chamber 8. Bubbles mixed in viscous muddy water are also removed securely and perfectly from the air vent hole 12. In such a way, no airlock phenomenon is generated in the volute chamber, and an idle running and a stopping of the lift capacity of the pumping-up and pumping-out can be prevented.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an improvement in the casing of a spiral bomb. [Prior Art] Horizontal shaft type submersible pumps, which are generally used for pumping and draining work at construction sites, are operated by putting the pump itself into the water.
We handle water mixed with sludge, sand, and gravel.

This type of pump uses a volute submersible pump, and as shown in FIG. The discharge ports 25 of 23 are provided upward in the tangential direction of the rotation outer circumferential circle of the impeller 21, and the uppermost part of the volute chamber 23 of the casing 22 is horizontally formed so as to be located at a higher position than the position of the volute winding start 24. ing. [Problems to be Solved by the Invention] For this reason, the conventional centrifugal pump described above is capable of removing air that is sucked in together with sludge water from the suction port on the front side of the pump casing during work at the site, that is, water bubbles mixed into the viscous sludge water. The air tends to collect and accumulate in the upper part of the volute chamber located higher than the volute winding start 24, and an air pocket 26 shown by diagonal lines occurs, causing an airlock phenomenon, which has a significant impact on pumping and drainage capacity and workability. ．． It is easy to remove the air from such air pockets on land, but it is extremely difficult to remove the air from the air pockets that form in the upper part of the vortex chamber of such pumps used underwater or in sludge water. could not be prevented.

The present invention aims to solve these problems. [Means for Solving the Problems] In order to achieve the above object, the casing 1 of the centrifugal pump of the present invention has a suction port 6 at the center of the front surface of the casing 1. Discharge port 7
will be established.

A volute winding start 9 is integrally formed from the casing 1 toward the throat 10 so as not to cross the vertical center line of the casing 1, and the inside of the volute chamber 8 and the discharge port 7 are connected at the winding start 9 near the gating body. An air vent hole 12 is provided.

The protrusion 11 forming the winding start 9 of the volute chamber 8 of the casing 1 in the casing 1 in the casing 1 has an upper surface formed into a concave arc surface 13 extending from the discharge port 7 provided at the center of the upper part of the casing 1 toward the throat 10, and a lower surface formed into a concave arc surface 13. Arc wall 14 separated from the volute chamber 8
The protrusion is formed into a triangular cross-sectional shape with a thick base and a thin tip, and an air vent hole 12 is provided in the protrusion obliquely in the tangential direction from the outer circumferential circle of the swirl chamber 8 toward the discharge port 7. It is what it is.

[Function] The above-mentioned centrifugal pump is used for pumping and drainage work at construction sites.
The bomb itself is operated while being immersed in water, and is used for pumping up and discharging water mixed with sludge, sand, and gravel.The air sucked in from the suction port 6 along with the sludge water is discharged into the upper center of the casing 1. An outlet 7 is provided, and since the top of the volute chamber 8 and the volute winding start 9 are located at almost the same height, there is no sealing pressure, and most of the fluid is discharged from the outlet 7 provided at the upper center of the casing. Therefore, air pockets inside the casing do not occur compared to conventional casings. In addition, water bubbles mixed in the viscous sludge water tend to accumulate in the upper part of the swirl chamber 8 at the beginning of winding 9 of the volute, but the air generated in part A of the swirl chamber 8 passes through the air vent l2 and is completely removed. The pump pressure does not drop and the pumping power is not affected.

Furthermore, the air sucked in during drought is discharged along the outer wall of the gating by the rotational force of the impeller.The discharge port 7 is provided in the center of the upper part, so that no water bubbles remain in the center of the upper part of the swirl chamber 8. , no airlock phenomenon occurs.

[Example] To explain based on an example with reference to the drawings, in FIGS. 1 and 2, 1 is a casing of a centrifugal pump, and 2 is a rotating shaft driven by a motor installed in a bomb body 3. , 4 is an impeller attached to the rotating shaft 2 with an impeller nut 17, 5 is a suction cover attached to the front surface of the casing, and 6 is a suction port formed in the center of the front surface of the casing 1. 7 is the discharge port of the casing 1 of the centrifugal pump, which is provided at the upper center of the casing 1 passing through its vertical center. In FIG. 1, the impeller 4 has blades 15 formed in an inverted V-shaped spiral shape continuous from the front part to the rear part in the rotation direction, and a shielding plate 16 on the front face facing the suction port 6, V-shaped with an open outer edge on the back. An impeller having a recess 17 is used to facilitate water pumping due to negative pressure on the back surface of the blade.

8 is the volute chamber of the volute pump, and the beginning of winding 9 of the vortex chamber 8
is formed by a protrusion 11 having a triangular cross-section and protruding from the casing 1 toward the throat 10 near the discharge side.

An air vent hole 12 is provided at the root of the protrusion 11 on the side of the casing body, which extends obliquely in a tangential manner from the outer circumferential circle of the swirl chamber 8 toward the upper center of the discharge port 7 .

The protrusion l1 forming the volute winding start 9 of the gating of the centrifugal pump has a thick base toward the throat 10 from the casing body 1 so as not to exceed the vertical center line of the casing, and an upper surface facing the discharge port. Expanding arc surface 13
The lower surface has a triangular cross-sectional shape with a pointed end forming an upwardly arcuate shape 14 along the spiral chamber 8.

Since the top of the swirl chamber 8 and the winding start 9 of the volute are approximately at the same height, not only no air pocket is formed, but also an air vent hole 12 is formed through which the inside of the swirl chamber 8 and the discharge port 7 pass.
Since the air is in communication with the pump, the air sucked in together with the sludge water, sand, and gravel water that is compressed and pumped and discharged by the rotation of the bomb can be discharged to the discharge port 7 through the air vent hole l2. There is no air trapped inside.

Furthermore, when installing the air vent hole 12 in the upper part of the swirl chamber 8, there is almost no reduction in the pumping and drainage capacity by considering the diameter and direction of the air vent hole. 3 and 4 show other embodiments of an impeller used in a centrifugal pump using the airlock prevention casing of the present invention.
It is also possible to use a blade 15a in the shape of the impeller 4 shown in the figure without the shielding plate on the front surface facing the suction port 6. [Effects of the Invention] Since the present invention has the above configuration, the air sucked in from the suction port together with the sludge water is discharged from the discharge port in the center of the casing without accumulating in the upper part of the swirl chamber in the gaging. In addition, water bubbles mixed into the viscous sludge water can be easily and completely removed from the air vent hole provided at the root of the casing at the beginning of winding in the vortex chamber, so air lock phenomenon inside the vortex chamber is prevented during operation. It is ideal as a sand pump for use while immersed in water, as it can operate smoothly without idling or stopping the pumping capacity or affecting workability.

[Brief explanation of drawings]

Figure 1 is a partially cutaway front view of the gating of the centrifugal pump of the present invention, Fig. 2 is a vertical sectional view of the centrifugal pump using the same gauging, and Fig. 3 is the same as Fig. 1 and Fig. 2. FIG. 4 is a front view showing another example of the impeller used, FIG. 4 is a partially cutaway plan view of the same, and FIG. 5 is a cross-sectional explanatory view of the casing of a conventional spiral bomb. 1...Casing 7...Discharge port 8...Vortex chamber 1 1 1 9...Start of winding 0...-Throat 1...Protrusion 2...Air vent hole

Claims (2)

[Claims] (1) In a horizontal shaft type centrifugal pump with a suction port at the center of the front, a discharge port is provided above the center of the pump casing, and an air bleed hole is provided at the root of the volute winding start of the casing, leading from the swirl chamber to the discharge port. A casing with airlock prevention for a centrifugal pump. (2) The volute winding start part of the volute pump casing is
It is formed by a protruding part with a triangular cross-section whose upper surface has a concave arc surface from the discharge port to the throat and is separated from the swirl chamber, and an air vent hole is provided in the protrusion in the tangential direction from the outer periphery of the swirl chamber toward the discharge port. A casing for preventing an airlock phenomenon of a centrifugal pump according to claim 1.