JPH04298699A - Bearing structure for multistage type submerged pump - Google Patents

Abstract

PURPOSE:To extremely reduce contact condition with a shaft and lengthen the life of bearings by arranging combination of static pressure bearings and dynamic pressure bearings on a bearing part of a multistage type submerged pump, setting the clearance between the dynamic pressure bearing and a rotating shaft less than the clearance between the static pressure bearing and the rotating shaft, and constituting so as to hold the shaft with the dynamic pressure bearing at starting and with the static pressure bearing at operation. CONSTITUTION:As for bearings supporting a pump rotating shaft 16, static pressure bearings 28 and dynamic pressure bearings 30 are appropriately combined and arranged, pressure oil is introduced from the high pressure part of the pump to the pocket 32 of the static pressure bearing 28 to hold the shaft 16 during rotation in non-contact condition, and the shaft at starting is held by the dynamic pressure bearing 30 of which clearance against the shaft 16 is set less than that of the static pressure bearing 28.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to a bearing structure for a multi-stage submerged pump, and in particular, the bearing of a multi-stage submerged pump is provided with a combination of a static pressure bearing and a hydrodynamic bearing, and the pump rotation shaft and The gap with the hydrostatic bearing is set slightly larger than that of the hydrodynamic bearing, and the load on the rotating shaft is supported by the hydrodynamic bearing when the pump is started. The present invention relates to a bearing structure for a multi-stage submerged pump configured to support the pump.

0002

2. Description of the Related Art In general, liquid bearings can be broadly classified into dynamic pressure types, static pressure types, and squeeze film types, depending on the principle of pressure generation. Dynamic pressure bearings are a method that works when two surfaces move relative to each other and the gap has a shape called a wedge-shaped gap that gradually narrows in the direction of movement. The relative movement of the surfaces causes the liquid to be dragged by its viscosity and forced into the wedge-shaped gap, creating pressure. Further, in a hydrostatic bearing, a liquid pressurized from the outside is introduced into a gap through a throttle and floated by the static pressure. In this case, the throttle adjusts the pressure within the gap when the gap changes, thereby providing rigidity to the bearing.

More specifically, in a hydrodynamic bearing, if we assume that the rotating shaft is rotating at a predetermined angular velocity and supporting a predetermined load, the axis of the rotating shaft when a load is applied is the same as that of the bearing. It is in an eccentric state where it has moved from the axis in the direction in which the load is applied, and at the same time, this direction of movement is in a state in which it has advanced in the rotational direction by a small angle with respect to the direction in which the load is applied. As a result, the bearing gap gradually narrows in the direction in which the load is applied, forming a wedge-shaped gap. The rotation of the shaft forces liquid into this wedge-shaped gap, creating pressure there that supports the load.

On the other hand, hydrostatic bearings are used when the relative speed between two surfaces is not sufficient or when high load capacity or rigidity is required. After passing through this orifice throttle and flowing into a pocket inside the bearing, it is discharged to the outside through a gap in the bearing. Therefore, the pressure of the liquid in the pocket is determined by the fluid resistance of the restriction and the fluid resistance of the gap.

Now, when a rotating shaft receives a load, the axis of the rotating shaft slightly moves by an amount of eccentricity from the center of the bearing in the direction in which the load is applied. In the static pressure type, unlike the above-mentioned dynamic pressure type, the direction of shaft movement coincides with the direction in which the load is applied. However, this is the case when the relative speed is low, and when the relative speed becomes high, an eccentric angle occurs as in the dynamic pressure type.

That is, in a hydrostatic bearing in which four pockets are equally spaced on the bearing surface, the bearing clearance on the side where the rotating shaft has moved decreases, and the fluid resistance in the clearance increases. On the other hand, since the fluid resistance of the throttle remains unchanged, the pressure in the pocket on the side where the axis has moved increases. Conversely, on the side where the shaft is farther away, the bearing clearance increases and the pocket pressure becomes lower. the result,
The load on the shaft is supported by the differential pressure distribution that occurs in each part where the pockets are arranged.

[0007] This type of bearing has conventionally been used in submerged pumps, and the thickness of the liquid film formed on the dynamic pressure bearing cannot be expected to be particularly thick, especially when the handling liquid is low viscosity like LNG. The load capacity of hydrostatic bearings decreases, and the load capacity of hydrostatic bearings increases when the supply pressure is high.
When the supply pressure is set to the pump discharge pressure, the load capacity at the time of pump startup is lost. Therefore, static pressure or dynamic pressure bearings are used either exclusively or in combination depending on the purpose of use.

[0008]

In particular, when both bearings are used in combination in a submerged type multistage pump, the following problems arise. That is, when the pump is started, the hydrostatic bearing has no force, so it comes into contact with the rotating shaft, increasing the amount of wear. In addition, during operation, hydrostatic bearings have a large load capacity, but hydrodynamic bearings have the disadvantage that the shaft is held near the center of the bearing, making it almost impossible to obtain the wedge effect of hydrodynamic bearings. was.

Therefore, an object of the present invention is to arrange a combination of a static pressure bearing and a hydrodynamic bearing in the bearing of a multi-stage submerged pump, and to make the gap between the pump rotating shaft and the hydrostatic bearing smaller than that of the hydrodynamic bearing. The load on the rotating shaft is supported by a hydrodynamic bearing when the pump is started, and is supported by a hydrostatic bearing or this bearing and a hydrodynamic bearing during pump operation. An object of the present invention is to provide a bearing structure for a multi-stage submerged pump that can significantly extend the life span of a conventional combination bearing.

0010

[Means for Solving the Problems] In order to achieve the above object, a multi-stage submerged pump is provided in which a hydrostatic bearing and a hydrodynamic bearing are combined and arranged in a bearing part that supports a pump rotating shaft to which a plurality of impellers are fixed. In the bearing structure of the pump, the hydrostatic bearing is configured to introduce handled liquid pressurized by the pump into a pocket formed on the bearing surface that supports the pump rotation shaft through a throttle, and The gap to the shaft is set slightly larger than the gap between the hydrodynamic bearings, and the load on the rotating shaft when the pump is started is supported by the hydrodynamic bearings, and the load during pump operation is supported by the hydrostatic bearings or between this bearing and the hydrodynamic bearings. It is characterized by being configured to support.

[0011]

[Operation] According to the bearing structure of the multi-stage submerged pump according to the present invention, the bearing of the multi-stage submerged pump is provided with a combination of a static pressure bearing and a hydrodynamic bearing, and the pump rotating shaft and the hydrostatic bearing are arranged in combination. The gap is set slightly larger than that of the hydrodynamic bearing, and the load on the pump rotating shaft is supported by the hydrodynamic bearing when the pump is started, and supported by the hydrostatic bearing or this bearing and the hydrodynamic bearing during pump operation. As a result, hydrostatic bearings have a large clearance to the rotating shaft and do not come in contact with the rotating shaft, so they do not need to be replaced at all, and hydrodynamic bearings also come into contact with the shaft only when the pump is started, which reduces the lifespan of the bearing. can be extended significantly.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of a bearing structure for a multi-stage submerged pump according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an overall sectional view of a multi-stage submerged pump showing an embodiment of the present invention, FIG. 2 shows a sectional view of a main part of a hydrostatic bearing, and FIG. 3 shows a partial sectional view of FIG. 2. In FIG. 1, reference numeral 10 indicates a multi-stage submerged pump, and this submerged pump 10 has a pump section 12.
This pump section 12 has a diffuser housing 18 partitioned by a partition wall 20 to define a plurality of pump chambers 22, and these pump chambers 22 are integrally configured with a rotational drive shaft 26 of the motor. The impellers 24 fixed to the pump rotating shafts 16 are rotatably housed and held, and the liquid sucked in from the impeller suction port at the uppermost stage of the pump is gradually pressurized and sent to each stage by a plurality of impellers. It is configured like this.

[0013] In this case, the pump rotating shaft 16 that applies rotational force to these impellers 24 is rotatably supported by a plurality of hydraulic bearings fixed to each partition wall 20, and these bearings absorb static pressure as described below. A suitable combination of bearings and hydrodynamic bearings is provided. That is, in this embodiment, a static pressure bearing 28 is arranged near the impeller of each of the first, third, and fourth pump chambers 22 at the lowest stage, and dynamic pressure bearings 30 are arranged near the impeller of the other pump chambers. Arrange as appropriate.

More specifically, as shown in the upper part of FIG. 2 and in FIG.
Four equally spaced pockets 32 are formed on the bearing surface that supports the
4 are formed in the radial direction. An annular groove 36 is formed in the outer partition wall of the bearing 28 so as to communicate with the orifice 34 , and an introduction pipe 40 is connected to the annular groove 36 so as to communicate with a flow passage 38 formed on the outer side of the diffuser housing 18 . has been done.

With this configuration, the high-pressure handling liquid discharged from the pump chamber 22 at the last stage is transferred to the pocket 32 of each hydrostatic bearing 28 through a flow path formed vertically outside the diffuser housing 18. 34 through an introduction pipe 36. In this case, in this embodiment, the hydrostatic bearing 2
The diameter gap No. 8 is set to 0.28 mm with respect to the shaft diameter of the pump rotating shaft 16 of 41 mm. Also, the lower part of Figure 2 and Figure 3
The dynamic pressure bearing 30 shown in (b) of FIG.
Three grooves 4 passing in the axial direction are equally spaced on the bearing surface that supports the
2 is formed, and the diameter gap of the dynamic pressure bearing 30 is set to 0.21 mm with respect to the shaft diameter of the pump rotation shaft 16 of 41 mm. In this way, the gap between the hydrostatic bearings is set to be slightly larger than the gap between the hydrodynamic bearings, and these bearings are appropriately combined and attached to the partition wall 20, respectively.

With the above-mentioned structure, the bearing of the multi-stage submerged pump has a slightly larger diameter gap when the pump is started, and the hydrostatic bearing 28 does not increase the pressure inside the pump, and the pressure oil remains in the pocket. However, the load at startup can be taken care of by the dynamic pressure bearing 30 with a small diameter gap. Also, during operation, high pressure oil raised by the pump is applied to the hydrostatic bearing 28.
The main load can be supported by this hydrostatic bearing. In this case, the hydrodynamic bearing 3
If the gap of 0 is appropriately set, a wedge effect can be obtained in the hydrodynamic bearing 30, and by using it in combination with a hydrostatic bearing, the load capacity of the entire bearing can be improved.

[0017]

As is clear from the embodiments described above, according to the present invention, a combination of a static pressure bearing and a dynamic pressure bearing is arranged in the bearing of a multi-stage submerged pump, and the pump rotating shaft and the static pressure The clearance with the bearing is set slightly larger than that of the hydrodynamic bearing, and the load on the rotating shaft when the pump is started is supported by the hydrodynamic bearing.
By configuring the pump to be supported by a hydrostatic bearing or this bearing and a hydrodynamic bearing during pump operation, the hydrodynamic bearing only makes contact with the rotating shaft when the pump is started, and the hydrostatic bearing does not rotate. Since it is possible to maintain a non-contact state inside the bearing, it is possible to significantly extend the life of the bearing, and in particular, it has excellent effects such as easy maintenance of the bearing because there is no need to replace the hydrostatic bearing, which has a complex structure. . Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is an overall sectional view of a multi-stage submerged pump showing an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a hydraulic bearing in which a static pressure bearing and a dynamic pressure bearing are arranged in combination.

FIG. 3 is a sectional view taken along line AA and line BB in FIG. 2;

[Explanation of symbols]

10 Multi-stage submerged pump 12 Pump section 14 Motor section
16 Pump rotation shaft

Claims (1)

[Claims] Claims: 1. A bearing structure for a multi-stage submerged pump, in which a hydrostatic bearing and a hydrodynamic bearing are arranged in combination in a bearing part that supports a pump rotating shaft to which a plurality of impellers are fixed, wherein the hydrostatic bearing is The pump is configured so that the pump-pressurized handling liquid is introduced into a pocket formed on the bearing surface that supports the pump rotation shaft through a throttle, and the gap between the pump rotation shaft and the pump rotation shaft is slightly larger than the gap between the hydrodynamic bearings. The multi-stage pump is configured such that the load on the rotating shaft is supported by a hydrodynamic bearing when the pump is started, and the load during pump operation is supported by a static pressure bearing or this bearing and a hydrodynamic bearing. Type submerged pump bearing structure.