JPH0128237B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a submersible pump, and in particular to an axial thrust reduction device suitable for a submersible pump having a structure in which it is difficult to attach an axial thrust reduction device to the main impeller. Regarding.

[Conventional technology]

In conventional submersible pumps, the entire hydraulic axial thrust load generated on the main impeller is supported by a thrust bearing installed in the motor chamber, or by an axial thrust bearing installed in the pump chamber near the main impeller. The remaining axial thrust load was reduced by a reduction device, and the remaining axial thrust load was supplementally supported by a thrust bearing installed in the motor chamber.

Incidentally, related pumps of this type include, for example, Japanese Patent Application Laid-open No. 144594/1983.

[Problem to be solved by the invention]

The former thrust bearing, which supports the entire hydraulic axial thrust load of the main impeller, is large and expensive, and has the disadvantage that it cannot be expected to have a long life because it is used under severe load conditions. Therefore,
In general submersible pumps, the latter method uses an axial thrust reduction device installed in the pump chamber near the main impeller, but due to the structure, the space for installing such an axial thrust reduction device is the main reason. For submersible pumps that are not located in the pump chamber near the impeller, the former method was unavoidably adopted. In addition, if the main impeller's fluid is not clean, the slits in the axial thrust reduction device installed inside the pump chamber will be severely worn, so the reduction device cannot be expected to operate normally, so the former method is unavoidably adopted. was.

An object of the present invention is to provide a device for reducing the axial thrust load transmitted to the thrust bearing in a submersible pump where an axial thrust reduction device cannot be installed in the pump chamber near the main impeller for structural or reliability reasons. It's about doing.

[Means to solve the problem]

The above purpose is to provide a submersible pump consisting of a submersible motor section and a main impeller section.
A thrust disk for a thrust bearing, which also serves as an auxiliary impeller for circulating motor cooling water, is mounted on the shaft in the motor chamber in which the submersible motor is installed so that the suction port of the auxiliary impeller faces the opposite side from the suction port of the main impeller. , by providing a slit to form an orifice in the surface near the outer periphery of the thrust disk or the opposite wall surface, which serves as a flow path when water discharged from the auxiliary impeller flows back to the suction side.
achieved.

[Effect]

By providing a slit that forms an orifice on the surface near the outer periphery of the thrust disk or on the wall facing it, the water flow that exits the discharge port of the auxiliary impeller and flows toward the submersible motor section through the slit. A pressure difference is created between the auxiliary impeller and the water flow flowing in the direction of the suction opening, which creates a downward thrust on the thrust disk, which thrust is in the opposite direction to the thrust produced by the main impeller. As a result, the thrust load applied to the shaft is reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The submersible pump according to the present invention includes a main impeller 1 and guide vanes 2 provided in a pump chamber A, and a motor stator 3, a motor rotor 4, shafts 7a and 7b, and a radial bearing 5 provided in a motor chamber B.
a, 5b, thrust bearings 6a, 6b, a thrust disk 8 which also serves as an auxiliary impeller for circulating motor cooling water, and an orifice 9a formed on the outer circumferential surface of the thrust disk, which serves as a flow path when water discharged from the auxiliary impeller flows back to the suction side. The part ring 9 is more familiar. As shown in FIG. 2, when the pump is rotating, most of the motor cooling water pumped up through the hole 8a formed in the thrust disk 8 flows through the radial groove provided in the upper thrust bearing 6a. It flows out to the outer periphery of the shaft 7b, flows further upward to cool the motor stator 3, flows inside the external heat exchanger 20, and returns to the lower part of the motor room. A part of the pumped water also flows through an orifice 9a formed by a ring 9, and further flows back through a radial groove provided in the lower thrust bearing 6b to the suction port of the auxiliary impeller, that is, the entrance of the hole 8a. do. The flow path resistance of the radial groove of the lower thrust bearing 6b is the orifice 9.
The pressure in the chamber 13 is only slightly higher than the pressure in the chamber 10, and the flow path resistance of the radial groove of the upper thrust bearing 6a is much smaller than the resistance of the upper thrust bearing 6a.
Since the resistance of the heat exchanger 20 etc. is set to be much smaller, the pressure in chamber 11 is only slightly higher than the pressure in chamber 12, and the pressure difference between them is
This is much smaller than the pressure difference between chamber 1 and chamber 13.
Therefore, a large pressure difference arises between chambers 11 and 13, which is approximately equal to the pressure generated by the auxiliary impeller, that is, the pressure difference between chambers 10 and 11. Therefore, a large downward hydraulic axial thrust is generated on the thrust disk 8. Since this direction is opposite to the direction of the thrust generated in the main impeller 1, the hydraulic axial thrust load of the main impeller 1 transmitted to the thrust bearing 6a can be reduced.

In this embodiment, an axial flow type orifice is shown as the orifice, but a radial flow type orifice as shown in FIG. 3 may be used without much difference in effectiveness. Of course, it is also possible to use an orifice that combines an axial flow type and a radial flow type.

〔Effect of the invention〕

As explained above, according to the present invention, by improving the thrust bearing structure of a conventional submersible pump, the load applied to the thrust bearing can be reduced and the life of the thrust bearing can be extended. Can be done.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a submersible pump according to the present invention, FIG. 2 is an enlarged vertical cross-sectional view of the X section in FIG.
FIG. 3 is a longitudinal sectional view showing another embodiment. 1... Main impeller, 6a... Upper thrust bearing,
6b...Lower thrust bearing, 8...Thrust disk that also serves as an auxiliary impeller, 9...Ring, A...
Pump room, B...Motor room, 10...Chamber 10, 1
1...Room 11, 12...Room 12, 13...Room 1
3.

Claims (1)

[Claims] 1. In a submersible pump consisting of a submersible motor part and a main impeller part, a thrust disk for a thrust bearing that also serves as an auxiliary impeller for circulating motor cooling water is installed in the motor chamber in which the submersible motor is installed, and the suction port of the auxiliary impeller is It is installed on the shaft so as to face the side opposite to the suction port of the main impeller, and a slit is formed near the outer periphery of the thrust disk or on the opposite wall surface, which serves as a flow path when water discharged from the auxiliary impeller flows back to the suction side. An axial thrust reduction device for a submersible pump, characterized in that an orifice is formed.