JP2764677B2 - Multi-stage pump - Google Patents

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

In recent civil engineering and construction works, various water stoppage methods have been adopted to improve construction efficiency and construction environment such as shortening the construction period.

[0004] However, the submersible pump used in the deep well method has an adverse effect due to the influence of the chemical solution injected into the soil by the above-mentioned water stopping method and soil components in a landfill near the shore. That is, depending on the environment in which the submersible multistage pump is installed, calcium carbonate or the like gradually adheres to the submerged pump during operation, and the impeller locks in time,
Many cases have led to inoperability.

FIG. 6 is an assembled sectional view showing an example of a conventional submersible multistage pump used in the deep well method. A pump unit 1 is provided above a submersible motor (not shown) for driving a submersible multi-stage pump, and a plurality of impellers 3, .. Are mounted in a multistage manner. A guide vane 5 for guiding the liquid discharged from the impeller 3 to the next stage is attached to the intermediate casing 4 that accommodates each impeller 3.

[0006]

However, in such a conventional submersible multistage pump, the 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. Also, on the rear side (upper side in the figure) of the impeller 3, the interval between the impeller 3 and the guide vane 5 forming the return flow path is configured to be narrow.

Therefore, if the groundwater contains calcium carbonate or the like, these substances adhere to the part of the pump unit 1 where the gap is formed during the pumping of the groundwater, and the submersible pump is turned on. In some cases, the impeller 3 is locked and becomes inoperable several days after the installation operation. Since such troubles greatly hinder the progress of the entire construction, a solution has been expected.

Further, when a large amount of sand or the like is mixed in the liquid handled by the pump, there is a problem that the pump portion 1 is inevitably worn out early, resulting in deterioration of performance.

The present invention has been made in view of the above circumstances, and even when pumping a handling liquid containing foreign substances such as calcium carbonate and sand, the pump performance is maintained for a long time without deterioration in pump performance. It is an object to provide a multi-stage pump that can be operated.

[0010]

In order to achieve the above-mentioned object, a multi-stage pump according to the present invention comprises a multi-stage pump in which an impeller and a casing for accommodating the impeller are arranged in multiple stages.
In the casing, a spiral chamber and a downstream side of the spiral chamber
An open-shaped guide vane with an open front surface on the main plate side of the impeller is also provided, and the impeller has an open shape with an open front surface, and the main plate of the impeller is formed by the spiral chamber and the guide vane. It is characterized by forming a partition wall with the flow path.

[0011]

According to the present invention, the impeller has an open shape in which the front face is open, and a sufficiently large space is secured between the front face of the impeller and the casing surface opposed thereto. Also, the distance between the back surface of the impeller and the casing surface opposed thereto is sufficiently large. An open guide vane and a swirl chamber are provided in the casing, and the impeller main plate also serves as a partition of a return flow path formed by the swirl chamber and the guide vane. Therefore, the entire flow path configuration including the return flow path is simple and a wide interval is ensured.

Therefore, even if a swirl is generated by the rotation of the impeller, and the handling liquid such as groundwater containing foreign substances such as calcium carbonate and sand is sucked into the inside of the pump from the suction port, the above-mentioned intervals are sufficiently set. Since it is large, rust, sand, scale, and the like do not adhere between the impeller and the casing surface during operation, and the handled liquid flows smoothly from the suction port to the discharge port according to the flow path in the pump.

[0013]

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

As a specific application of the multi-stage pump 10 according to the present invention, there is a case in which the multi-stage pump 10 is installed in a deep well to pump groundwater 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 substances such as sand and calcium carbonate.

Examples of cases where the multi-stage pump 10 is used for applications other than the deep well method include a general deep well in which a large amount of sand is contained in pumped water and a so-called well basin. This `` well erosion '' means that the well wall is not stable immediately after drilling the well and a large amount of sand is sucked up from the well casing. Stabilizing the inner wall of the well. The other pump used for this is referred to as a well sweeping pump, and the multi-stage pump 10 of the present invention is used for this pump.

As shown in FIG. 1, a multi-stage pump 10 for discharging a handled liquid such as groundwater is provided with a submersible motor 11 disposed below and serving as a driving source, and a pump unit mounted on the upper part of the submersible motor 11. 12 are provided. Further, a plurality of (three in this embodiment) impellers 13 of the pump section 12 are mounted on a rotating shaft 14 projecting upward from the submersible motor 11 to form a multi-stage and open front (lower in the figure). It is formed in a vortex structure in which the distance 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 provided upright above a motor shaft 31 which projects upward from the underwater motor 11 and is driven to rotate. The motor shaft 31 and the pump shaft 32 are connected and fixed by a cylindrical coupling 33 and rotate around a common rotation center axis B. Motor shaft 31 and pump shaft 32
Are fixed to the cylindrical coupling 33 by keys 34, 35 and setting screws 36, 37 screwed into the cylindrical coupling 33, respectively. The rotating shaft 14 is constituted by a motor shaft 31, a cylindrical coupling 33, and a pump shaft 32 that rotates integrally with the motor shaft 31 via the cylindrical coupling 33. Pump shaft 32 of the present embodiment
Are considerably long in the longitudinal direction, so that the lower bearing 38 and the upper bearing 3 provided at the lower and upper parts of the pump shaft 32, respectively.
9, the lower part and the upper part are rotatably supported so as not to cause lateral displacement.

A lower sleeve 38, which is supported in the radial direction by a lower bearing 38 and is disposed at a predetermined position in the axial direction, for positioning the impeller 13 at a position immediately above the cylindrical coupling 33, is provided. 32. On the upper part of the lower sleeve 40, a 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 and rotate integrally with the pump shaft 32.

Further, the pump shaft 32 is rotatably slidably contacted with a sand collar 44 located above the upper distance piece 42 and the upper bearing 39.
And a nut 47 which is screwed into and fixed to a bolt 46 formed at the upper end of the pump shaft 32. The members such as the impeller, the distance piece, and the sleeve attached to the pump shaft 32 are tightly fixed to each other by tightening a nut 47 so as to prevent play. The bolt 46 and the nut 47 are attached to a cap 46 which is detachably attached.
a.

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

As shown in FIG. 2 , the impeller 13 in the vortex structure has a boss 73 fixed to the rotating shaft 14 by a key 43 and is formed in a disk shape integrally formed radially outward from the boss 73. A main plate 74 and a plurality of arc-shaped blades 75 fixed forward and on the front surface of the main plate 74 (below FIGS. 1 to 3) are provided. A swirling chamber 76a and a return flow path 76b are formed in the intermediate casing 64 constituting the casing. The return passage 76b is formed by an open guide vane 77 formed integrally with the intermediate casing 64, and the main plate 74 of the impeller 13 is formed.
Serves also as a partition wall between the spiral chamber 76a and the return channel 76b.

FIG. 3 shows the details of the planar arrangement of the flow paths in the casing. In the figure, the return flow path 76b is indicated by solid-line hatching, and the spiral chamber 76a is indicated by broken-line hatching.
The dashed line indicates the outer diameter D of the impeller. As shown in FIG. 3, a volute shape is formed from the start portion S to the portion A of the spiral chamber 76a, and at the same time, the main plate 7 of the impeller 13 is formed from the portion A.
The flow is transferred to the return flow path 76 b through the outer periphery of the impeller 4, and the return flow path 76 b is connected to the next inlet of the 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 plan view of the main plate 74 of the impeller 13 serving as a partition wall. In the figure, the impeller 13 is indicated by two-dot chain lines.

In order to prevent foreign matter from being caught between the impeller 13 and the guide vane 77, the distance C _S described above is made sufficiently large as shown in FIG.
The back 79 of the impeller 13 and the guide vanes 7 facing the back 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 inclination angle α of the guide vane 77 be α <90 ° within a range in which the dimension W between the surfaces of the intermediate casing 64 is economical. As described above, the impeller 13 has a swirl chamber 76a whose front surface is widely opened to generate a vortex of water, and a sufficiently large interval C between the impeller 13 and the casing 64.
_s , C _{R and} C _D are secured.

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

In this case, even if foreign matter such as calcium carbonate or sand is contained in the water, 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 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 dimension, no foreign matter such as rust, sand, scale, etc. is caught between the impeller 13 and the casing 64. Further, the entire flow path including the return flow path 76b in the casing has a simple configuration without a stagnation portion (binding portion). As a result, the problem that calcium carbonate or the like sticks to the inside of the pump can be greatly reduced, and the pump 10 can be operated stably for a long time, greatly improving the efficiency of the entire construction. Can be.

Further, since the structure of the pump section 12 is a vortex structure, even if sand or mud having abrasion properties is contained in the handling liquid, the inside of the pump is less worn and the pump performance is reduced. The pump can be operated stably for a long time.

Further, since the submersible motor 11 is arranged at the lower part and the pump part 12 is arranged at the upper part, 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 small-diameter well 90 excavated deeper than the ground GL, thereby increasing the efficiency of the excavation work and reducing the cost of the work. Can be realized.

[0030]

As described above, according to the present invention, the following effects can be obtained. (1) Since the flow path configuration is simple and a wide gap is secured, a long-term operation can be continued even in an operation in which a large amount of a fixed component such as calcium carbonate is contained in the pumped liquid. (2) Since the guide vane has an open shape and the other flow passages are formed in a casing having a good visibility, maintenance properties such as cleaning of the inside of the casing are excellent. (3) Since the spiral chamber and the return flow path are integrally formed as a smooth flow path in the casing, the pump performance is good. (4) Since the impeller has a vortex structure, the effect of abrasion due to sand and the like is small, and the performance is not easily deteriorated.

[Brief description of the drawings]

FIGS. 1 to 5 show one embodiment of the present invention.
FIG. 1 is an assembled sectional view of the submersible multi-stage pump.

FIG. 2 is a partially enlarged cross-sectional view of the submersible multi-stage pump shown in FIG.

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

FIG. 4 is an explanatory view showing a planar arrangement of an impeller main plate serving as a partition.

FIG. 5 is a sectional view showing a state where 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]

DESCRIPTION OF SYMBOLS 10 Submersible multistage pump 11 Submersible motor 12 Pump part 13 Impeller 14, 14a Rotating shaft 15 Open side front surface 17 Casing surface C _S spacing 64 Intermediate casing 74 Impeller main plate 76a Swirling chamber 76b Return flow path 77 Guide vane

Continuation of the front page (51) Int.Cl. ⁶ identification code FI F04D 29/44 F04D 29/44 E 29/70 29/70 G (58) Investigated field (Int.Cl. ⁶ , DB name) F04D 13 / 00 F04D 1/08 F04D 7/04 F04D 13/08 F04D 29/42 F04D 29/44 F04D 29/70

Claims (1)

(57) [Claims] 1. A multi-stage pump in which an impeller and a casing accommodating the impeller are arranged in multiple stages, wherein a spiral chamber is provided in the casing, and a main plate of the impeller is provided downstream of the spiral chamber.
An open shape guide vane with an open front side is also provided, and the impeller has an open shape with an open front,
A multi-stage pump, wherein a main plate of the impeller constitutes a partition between the spiral chamber and a return flow path formed by the guide vane.