JP2001003888A - Impeller of submersible motor pump for deep well - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out an operation with high efficiency, shorten a length of a pump, and reduce manufacturing costs and product weight by forming a device so as to satisfy a specified formula in relation to an outer diameter of a front shroud for composing an impeller of a centrifugal pump, a width of a blade, and an outer diameter of a rear shroud. SOLUTION: This impeller 1 of an impeller for submersible motor pump for deep well is constituted by annularly arranging many blades 1c between a front shroud 1a and a rear shroud 1b. In this case, each outer diameter r of the front shroud 1a and the blade 1c is formed in a same size, and an outer diameter r of the rear shroud 1b is formed nearly smaller than that of the front shroud 1a and the blade 1c. When a width of the blade 1c is set to S, a design is carried out so as to set a value in the relational expression of (R-r)/S to a range of 0.3 to 0.6. It is thus possible to increase a net pump head at a much water quantity side, and it is also possible to reduce desired power in a region of a nearly gamut where a pump is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an impeller of a submersible motor pump for deep wells.

[0002]

2. Description of the Related Art A submersible motor pump for a deep well has a well lid or a mounting band provided on a ground portion of the deep well whose inner wall is reinforced by using a steel pipe or the like. It is used suspended below the water level. Steel pipes used to reinforce the inner walls of wells are usually JI
The size specified in the S standard is used, and the inner diameter is 7
5mm (3 inches), 100mm (4 inches), 125
mm (5 inches), 200 mm (8 inches), 250 m
m (10 inches) and 300 mm (12 inches) are often used.

The submersible pumps for deep wells are designed according to the inner diameter size of each steel pipe so that they can exhibit a predetermined capability after installation and have good installation workability. Here, in order to achieve the specified performance and improve the installation workability, the distance between the inner wall of the well and the outer periphery of the pump should be ensured so that the resistance in the pump strainer does not increase and the pump performance is not impaired. In addition, when the pump is installed in the well, it is necessary to prevent the pump from being damaged by contact with the inner wall of the well. Then, it is necessary to design the maximum outer diameter of the deep well submersible pump as small as possible. Conventionally, in order to reduce the outer diameter of the pump, a diagonal flow pump is used which only requires the maximum outer diameter of the pump to be slightly larger than the outer diameter of the impeller.

[0004]

The mixed flow pump has the following problems. As the impeller and / or guide blades become longer in the axial direction,
The length of the casing that houses them is also increased, which leads to an increase in the axial length and weight of the product. As the impeller and / or guide blades become longer in the axial direction,
The main shaft of the pump becomes longer. Bearings that support the main shaft of the pump are usually provided at both ends of the main shaft. However, when the main shaft is longer, the interval between the bearings is longer, so that the bending of the main shaft increases.
Therefore, it is necessary to take measures to reduce the bending, for example, by providing an intermediate bearing, and there is a problem that the structure becomes complicated and the manufacturing cost increases. It is difficult to manufacture them from the shapes of the impeller and the guide blades except for the method of integral molding such as casting and injection molding. The minimum wall thickness that can be cast is generally thicker than a steel plate or the like, and there is necessarily a limit to the weight reduction.

In order to solve such a problem, there is a method of using a centrifugal impeller pump whose axial length is shorter than that of a mixed flow pump and which has a wide range of choices in the method of manufacturing the impeller. . However, centrifugal pumps that have a larger outer diameter than mixed-flow pumps of the same performance, as described above, have the impellers and guide blades in ideal shapes due to the limited outer dimensions of deep-well submersible motor pumps. It cannot be designed, resulting in reduced efficiency. An object of the present invention is to provide a deep well submersible motor pump capable of operating with high efficiency even when a centrifugal pump is employed, shortening the overall length of the pump, and reducing the production cost and product weight.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a relational expression wherein the outer diameter of the front shroud constituting the impeller of the centrifugal pump is R, the width of the blade is S, and the outer diameter of the rear shroud is r. The numerical value of R−r) / S is set in the range of 0.3 to 0.6.

[0007]

1 shows an impeller of a submersible motor pump for a deep well according to the present invention, wherein A is a perspective view, B is a front view, and FIG. 2 is a pump having the impeller mounted thereon. FIG. 2 is an explanatory sectional view of the device. 1 is an impeller according to the present invention, 1a is a front shroud of the impeller, 1b is a rear shroud, and 1c is a blade. As shown in the drawing, in the impeller 1 of the present invention, the outer diameter R of the front shroud 1a and the blade 1c is equal, but the outer diameter r of the rear shroud 1b is slightly smaller than the front shroud 1a and the blade 1c. The dimensions are as follows. And the blade 1c
When the width dimension of S is S, a numerical value based on the relational expression of (R−r) / S shall be obtained. Thus, the value of the above relational expression is designed to be in the range of 0.3 to 0.6.

FIG. 2 is a cross-sectional view of a pump device to which the impeller 1 having the above-mentioned structure is attached, wherein 2 is a motor, 3 is a pump shaft,
Reference numerals a and 4b denote bearing casings provided with bearings for supporting the motor shaft between the lower strainer casing 5 and the upper discharge casing 6;
It is a some intermediate casing interposed between a and 4b.

The impeller 1 and the guide vanes 8 are attached to each of the plurality of intermediate casings 7 in a paired manner. It is a spacer for fixing at the interval position. The guide vanes 8 are mounted in a sandwiched state between the adjacent intermediate casings 7. 10 is a liner ring.

As is apparent from the above drawings, each impeller 1,
Are mounted so that the front shroud 1a faces the lower strainer casing 5 where the motor 2 is located, and the rear shroud 1b faces the discharge casing 6.

FIG. 3 is an explanatory view of a use state of the deep well pump device. Reference numeral 11 denotes an underground pipe, reference numeral 12 denotes a pumping pipe which is vertically suspended from the ground, and a discharge casing 6 of the pump device is provided at the end thereof. It is linked. Reference numeral 13 denotes a power cable.

When the motor 2 is driven via the power cord 13 from the ground in the above-described mounting configuration and arrangement, each impeller 1 on the shaft is rotated, and the water 14 below the ground is moved to the lower strainer. The water flows from the through holes formed in the peripheral surface of the casing 5 and is pumped from the pumping pipe 12 to the ground via the guide impellers 8 and the discharge casing 6.

The inventor of the present invention performed a comparative operation between the conventional configuration of the impeller and the configuration of the present invention by using the above-mentioned apparatus in operation, and obtained performance graphs as shown in Tables 1, 2 and 3. Was.
In each of the tables, the impeller A is a conventional product, whereas the impeller B is obtained by setting the value of the above relational expression to 0.4, and the impeller C
Shows a discharge amount-one shaft power ratio curve (Table 1), a discharge amount-efficiency curve (Table 2), and a discharge amount-total head ratio curve (Table 3) of 0.47.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

In the discharge amount-one-axis power ratio curve shown in Table 1, the discharge amount is 0.
B and C from impeller A up to 50 l / min
Has a high shaft power, but thereafter decreases in the order of the impellers A, B, and C.

From the discharge amount-one-axis power curve in Table 2 and the discharge amount-total head ratio curve in Table 3, it can be clearly understood that the efficiency of the impeller C is the best, and the efficiency of the impeller is next to B and A.

In the discharge amount-total head ratio curve of Table 3, the discharge amount is 0.
To 50 liter / min, there is almost no difference in the total lift of each impeller. However, at around 170 liter / min, impellers B and C are slightly higher, and at 250 liter / min, impellers A and B are almost equal. However, the impeller C exhibits a high ability.

In addition, from a number of experimental examples of the present inventor, when the value of the relational expression (R-r) / S is 0.3 or less, there is not much difference from the conventional product in terms of the above-mentioned effects. On the other hand, if the ratio is 0.6 or more, the centrifugal action of the impeller is impaired, and the efficiency of the impeller decreases, so this is limited.

[0021]

According to the present invention, the outer diameter of the rear shroud r is made smaller than the outer diameter R of the front shroud and the blade, so that the total head is increased particularly on the large water flow side. In addition, the required power can be reduced in almost all areas where the pump is used, and the operation can be performed with high efficiency. Therefore, even when a centrifugal impeller is used, it is possible to obtain a predetermined capacity, and to supply a submersible motor pump for a deep well with a reduced overall length of the pump, reduced manufacturing cost and reduced product weight.

[Brief description of the drawings]

FIG. 1 shows an impeller of a motor pump for deep wells according to the present invention, wherein A is a perspective view and B is a plan view.

FIG. 2 is an explanatory sectional view of a pump device to which the impeller is mounted.

FIG. 3 is a diagram showing a use state of the device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Impeller 1a Front shroud 1b Rear shroud 2 Motor 3 Pump shaft 4a, 4b Bearing casing 5 Lower strainer casing 6 Upper discharge casing 7 Intermediate casing 8 Guide vane 12 Pumping pipe

Claims (1)

[Claims] 1. The numerical value of the relational expression (R-r) / S, where R is the outer diameter of the front shroud, S is the width of the blade, and r is the outer diameter of the rear shroud, is 0.3 to 0.1. 6. An impeller for a submersible motor pump for deep wells, wherein