JPH06323289A - Multistage pump - Google Patents

Abstract

PURPOSE:To provide a multistage pump capable of safely running continuously for a long time without degrading the pump performance even if a handled liquid containing foreign matters such as calcium carbonate or sand is pumped up. CONSTITUTION:In a multistage pump having impellers 13 and casings 16 receiving the impellers 13 disposed on multiple stages are provided in parallel swirl chambers 76a in casings 64 and open-shaped guide vanes 7 having the front surface opened to the downstream of the swirl chamber 76a. The impeller 13 is open-shaped to have the front surface opened and a main plate 74 of the impeller 13 constitutes a partition wall between the swirl chamber 76a and a return flow path 76b formed of the guide vane 77.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-stage pump, and more particularly to a multi-stage pump having an open guide vane and a spiral chamber in a casing.

[0002]

2. Description of the Related Art When performing a foundation work in civil engineering / construction work, there is a case of excavating deeper than the ground to construct a building. In order to lower the groundwater level below the underground excavation surface of the excavated part and maintain this level,
The deep well method (deep well method) is often used. In this method, a plurality of deep wells are dug in the construction area, and a submersible multistage pump is installed in the deep wells to discharge groundwater, thereby lowering and maintaining the groundwater level.

Further, in recent civil engineering / construction works, various water stopping methods are adopted to improve work efficiency and work environment such as shortening the work period.

However, the submerged pump used in the deep well method is adversely affected by the effects of the chemical solution injected into the soil by the water stopping method and the soil components such as the landfill near the coast edge. That is, depending on the environment in which the submersible multi-stage pump is installed, calcium carbonate or the like gradually adheres to the submersible pump during operation, and the impeller eventually locks.
There are many cases of driving failure.

FIG. 6 is an assembled sectional view showing an example of a conventional submersible multistage pump used in the deep well method. A submersible motor (not shown) for driving a submersible multi-stage pump is provided with a pump unit 1 on its upper portion, and a rotary shaft 2 coupled to the shaft of the submersible motor and protruding upward has a plurality of impellers 3. 3 ... are mounted in multiple stages. A guide vane 5 for guiding the pumped liquid discharged from the impeller 3 to the next stage is attached to the intermediate casing 4 that houses each impeller 3.

[0006]

However, in such a conventional submersible multistage pump, a liner ring 6 is provided between the suction side axial portion of each impeller 3 and the intermediate casing 4. The distance between the liner ring 6 and the impeller 3 is very small. Further, also on the back side of the impeller 3 (upper side in the figure), the interval between the vane wheel 3 and the guide vanes 5 forming the return passage is narrow.

Therefore, when the groundwater contains calcium carbonate or the like, these substances adhere to the portion of the pump portion 1 where the gap is formed while pumping the groundwater. In some cases, the performance is deteriorated, and in the early cases, the impeller 3 is locked and becomes inoperable within a few days after the installation operation. Since such troubles greatly hinder the progress of the entire construction, a solution for them was expected.

Further, when a large amount of sand or the like is mixed in the liquid handled by the pump, there is a problem in that early wear of the pump portion 1 is unavoidable and performance is deteriorated.

The present invention has been made in view of the above circumstances. Even when a handling liquid containing a foreign substance such as calcium carbonate or sand is pumped, the pump performance does not deteriorate and is stable for a long time. An object is to provide a multistage pump that can be operated.

[0010]

In order to achieve the above object, a multistage pump of the present invention is a multistage pump in which an impeller and a casing for accommodating the impeller are arranged in multiple stages.
Inside the casing, a swirl chamber and an open guide vane whose front surface is open on the downstream side of this swirl chamber are provided side by side.
The impeller has an open shape with an open front surface, and a main plate of the impeller constitutes a partition wall between the swirl chamber and a return passage formed by the guide vane.

[0011]

In the present invention, the impeller has an open shape with its front face opened, and a sufficiently large distance is secured between the front face of this impeller and the casing surface facing it. In addition, a sufficiently large gap is secured between the back surface of the impeller and the casing surface facing the back surface of the impeller. An open guide vane and a swirl chamber are provided inside the casing, and the impeller main plate also serves as a partition wall of the return passage formed by the swirl chamber and the guide vane. Therefore, the entire flow path configuration including the return flow path is simple and wide intervals are secured.

Therefore, even if a swirl is generated due to the rotation of the impeller and the handling liquid such as ground water containing foreign substances such as calcium carbonate and sand is sucked into the inside of the pump portion through the suction port, the above-mentioned intervals will be sufficient. Since it is large, rust, sand, scale, etc. do not adhere between the impeller and the casing surface during operation, and the handled liquid smoothly flows from the suction port to the discharge port according to the flow path in the pump.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. Fig. 1 is a sectional view of the submersible multi-stage pump.
2 is a partially enlarged cross-sectional view of the submersible multistage pump shown in FIG. 1, FIG. 3 is a view of a flow path in a casing as seen from the suction side, FIG. 4 is a view showing a planar arrangement of an impeller main plate serving as a partition wall, and FIG. It is sectional drawing which shows the state which installed the submersible multistage pump shown in FIG. 1 in the deep well.

A specific application of the multi-stage pump 10 according to the present invention is to install groundwater in a deep well when foundation work is performed by the deep well method. Usually, deep wells are often small wells with a small inner diameter, and groundwater often contains a large amount of foreign matter such as sand and calcium carbonate.

As a case where the multistage pump 10 is used for purposes other than the deep well construction method, there are a general deep well in which a large amount of sand is contained in pumped water, and a so-called well well. This "well well" means that the well wall is not stable immediately after excavation of the well and a large amount of sand is taken up from the well casing, so before the installation of the main pump, another pump is temporarily used to pump water. It means to stabilize the inner wall of the well. The separate pump used for this is called a well scour pump, and the multistage pump 10 of the present invention is used for this pump.

As shown in FIG. 1, a multistage pump 10 for discharging a handling liquid such as groundwater is a submersible motor 11 arranged at a lower portion and serving as a drive source, and a pump portion mounted on an upper portion of the submersible motor 11. 12 and 12. Further, a plurality of impellers 13 of the pump unit 12 (three in this embodiment) are attached to the rotary shaft 14 protruding upward from the submersible motor 11 to form a multi-stage, and the front surface (downward in the drawing) is opened. It has a vortex structure in which the gap C _S between the open side front surface 15 of the impeller 13 and the casing surface 17 of the casing 64 facing the open side front surface 15 is sufficiently large.

A pump shaft 32 is erected above a motor shaft 31 which is projected from the submersible motor 11 and driven to rotate. The motor shaft 31 and the pump shaft 32 are connected and fixed by a tubular coupling 33 and rotate about a common rotation center axis B. Motor shaft 31 and pump shaft 32
Are fixed to the tubular coupling 33 by keys 34 and 35 and set screws 36 and 37 screwed into the tubular coupling 33, respectively. The rotary shaft 14 is configured by the motor shaft 31, the tubular coupling 33, and the pump shaft 32 that rotates integrally with the motor shaft 31 via the tubular coupling 33. Pump shaft 32 of the present embodiment
Is considerably long in the longitudinal direction, the lower bearing 38 and the upper bearing 3 provided on the lower and upper portions of the pump shaft 32, respectively.
9, a lower portion and an upper portion are rotatably supported so as not to cause lateral displacement.

A lower sleeve 40, which is supported in the radial direction by a lower bearing 38 and is used to position the impeller 13 at a predetermined axial position, is positioned immediately above the tubular coupling 33 and is located on the pump shaft. It is fitted in 32. At the upper part of the lower sleeve 40, the lower impeller 13A,
Distance piece 4 to secure the distance between the impellers
1, the intermediate impeller 13B, the distance piece 41, the upper impeller 13C, and the upper distance piece 42 are sequentially fitted to the pump shaft 32. The lower, middle, and upper impellers 13 are locked to the pump shaft 32 by a key 43 so as to rotate integrally with the pump shaft 32.

Further, the pump shaft 32 is rotatably slidably in contact with a sand collar 44 located above the upper distance piece 42 and an upper bearing 39, and at the same time, the pump shaft 32.
A sleeve 45 that integrally rotates with a nut 47 and a nut 47 that is screwed and fixed to a bolt 46 formed on the upper end of the pump shaft 32 are sequentially attached. The above-mentioned members such as the impeller, the distance piece, and the sleeve, which are attached to the pump shaft 32, are tightly fixed to each other by tightening the nut 47 so that there is no play. The bolt 46 and the nut 47 are attached to the cap 46 that is detachably attached.
It is covered by a.

The body portion of the pump portion 12 has a suction casing 63 having a flange 62 fixed to the submersible motor 11 by a bolt 61, and a plurality of stacks (three in this embodiment) stacked on top of the suction casing 63. Individual) intermediate casings 64 and a discharge casing 65 attached to the uppermost intermediate casing 64. The lower part 68 of the tightening band 67 is locked to the tightening band seat 66 formed in the suction casing 63, and the nut 70 is fastened to the bolt 69 fixed to the upper end part of the tightening band 67 to discharge the upper end part. By fixing to the casing 65, the entire casings 63 to 65 are fixed by tightening. Therefore, each casing can be disassembled by removing the nut 70 screwed to the bolt 69.

As shown in FIG. 3, the impeller 13 in the vortex structure has a boss 73 fixed to the rotary shaft 14 by a key 43 and is a disk-shaped integrally formed radially outward from the boss 73. The main plate 74 is provided with a plurality of arcuate blades 75 fixed to the front surface (downward in FIGS. 1 to 3) of the main plate 74 so as to be forward. A swirl chamber 76a and a return flow path 76b are formed in the intermediate casing 64 that constitutes the casing. The return flow path 76b is formed by an open-shaped guide vane 77 integrally formed with the intermediate casing 64, and the main plate 74 of the impeller 13 is provided.
Also serves as a partition wall between the swirl chamber 76a and the return flow path 76b.

FIG. 3 shows details of the planar arrangement of the flow passages in the casing. In the drawing, the return flow passage 76b is shown by solid line hatching, and the spiral chamber 76a is shown by broken line hatching.
The one-dot chain line indicates the outer diameter D of the impeller. As shown in FIG. 3, the swirl chamber 76a has a volute shape from the start portion S to the portion A, and at the same time, from the portion A to the main plate 7 of the impeller 13.
The flow moves to the return flow path 76b through the outer periphery of 4, and the return flow path 76b is connected to the inlet of the next intermediate casing 64 along the shape of the guide vane 77 on the back side of the main plate 74 of the impeller 13.

FIG. 4 shows a plane arrangement of the main plate 74 of the impeller 13 which serves as a partition wall. In the figure, the impeller 13 is indicated by a two-dot chain line hatching.

In order to prevent foreign matter from being caught between the impeller 13 and the guide vanes 77, the above-mentioned interval C _{S is set} to a sufficiently large size as shown in FIG.
The back surface 79 of the impeller 13 and the guide vanes 7 facing the back surface 79.
It is the interval C _R, and a sufficiently large dimension each interval C _D also between the outer peripheral edge 80 and guide vanes 77 opposed thereto of the impeller 13 between the 7.

Further, it is preferable that the guide vanes 77 have an inclination angle α of α <90 ° within a range in which the surface dimension W of the intermediate casing 64 is economical. In this manner, the impeller 13 has a front surface that is widely opened to form the swirl chamber 76a that generates a swirl of water, and a sufficiently large distance C between the impeller 13 and the casing 64.
_s , C _{R, and} C _D are secured.

Next, the operation of the submersible multistage pump configured as described above will be described. When the submersible motor 11 is driven to rotate the impeller 13 together with the rotating shaft 14 in the spiral chamber 81, ground water and the like are sucked from the suction strainer 82 of the suction casing 63 and then guided into the pump. The water subjected to the centrifugal action of the impeller 13 is suitably pressure-recovered through the spiral chamber 76a and the return flow path 76b, is guided to the impeller 13 of the next stage, and this is repeated.
5 is discharged through the discharge port 65a to the outside.

In this case, even if the water contains a foreign substance such as calcium carbonate or sand, the pump portion 12 has a vortex structure, and the gap between the open side front surface 15 of the impeller 13 and the casing surface 17 is increased. interval C _S of has become a large size enough, further distance C _R of the other part, C
_{Since D} also has a sufficiently large size, foreign matter such as rust, sand and scale is not caught between the impeller 13 and the casing 64. In addition, the entire flow passage including the return flow passage 76b in the casing has a simple structure without a stagnation portion (stitch portion). As a result, troubles such as calcium carbonate sticking to the inside of the pump can be significantly reduced, and the pump 10 can be stably operated for a long time, thereby significantly improving the efficiency of the entire construction. You can

Further, since the structure of the pump portion 12 is a vortex structure, even if sand or mud having abradability is contained in the liquid to be handled, the inside of the pump is less likely to be worn and the pump performance is deteriorated. Therefore, the pump can be continuously operated for a long time and stably.

Further, since the submersible motor 11 is arranged in the lower portion and the pump portion 12 is arranged in the upper portion, the outer diameter of the submersible multistage pump 10 can be reduced. Therefore, as shown in FIG. 5, it becomes possible to install and operate the pump 10 inside the excavation well 90 having a small inner diameter that is excavated deeper than the ground GL, thereby improving the efficiency of excavation work and reducing the cost of construction. Can be realized.

[0030]

As described above, according to the present invention, the effects listed below are exhibited. (1) Since the flow path configuration is simple and a wide gap is secured, long-term operation can be continued even in the operation in which the pumping liquid contains a large amount of adhered components such as calcium carbonate. (2) Since the guide vanes have an open shape and the other flow passages have a structure with good visibility, maintenance such as cleaning inside the casing is good. (3) The swirl chamber and the return passage are integrally formed as a smooth passage in the casing, so that the pump performance is good. (4) Since the impeller part has a vortex structure, it is less affected by abrasion due to sand, etc., and is less likely to deteriorate in performance.

[Brief description of drawings]

1 to 5 are views showing an embodiment of the present invention,
FIG. 1 is an assembled sectional view of a submersible multistage pump.

FIG. 2 is a partially enlarged sectional view of the submersible multistage pump shown in FIG.

FIG. 3 is an explanatory view of a flow path in a casing as viewed from a suction side.

FIG. 4 is an explanatory diagram showing a planar arrangement of an impeller main plate that serves as a partition wall.

5 is a cross-sectional view showing a state in which the submersible multistage pump shown in FIG. 1 is installed in a deep well.

FIG. 6 is an assembled sectional view showing the entire structure of a conventional submersible pump.

[Explanation of symbols]

10 water multistage pump 11 submersible motor 12 pump 13 impeller 14,14a rotary shaft 15 open side front 17 casing surface C _S spacing 64 intermediate casing 74 impeller main plate 76a volute 76b return channel 77 guide vanes

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area F04D 29/70 G

Claims (1)

[Claims] 1. A multi-stage pump in which an impeller and a casing for accommodating the impeller are arranged in multiple stages, and a swirl chamber inside the casing, and an open guide vane having a front surface open to the downstream side of the swirl chamber. And an impeller having an open shape with an open front surface, and a main plate of the impeller constitutes a partition wall between the swirl chamber and the return flow passage formed by the guide vane. Multi-stage pump.