RU2444831C1 - Radial thrust plain bearing on idle shaft extension of vetockhin induction motor for oil-and-gas wells - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: downhole induction motor shaft idle extension supports radial thrust plain bearing to make rotor aligned with stator bore and keep working clearance between rotor and stator invariable. Proposed induction motor comprises housing 1, end shield 4, shaft 6 with idle extension provided with moving thrust sleeve 8 that has thrust sliding surface 9 radial sliding surface 10. Fixed bearing insert 11 made from high-density powder material and having similar sliding surfaces 9 and 10 is tightly fitted in cylindrical recess of said bearing shield. Sliding pairs are cooled down via free clearance 12 and bearing shield holes 13. Cooling water is fed outside via holes 14 and 15 in housing 1.

EFFECT: improved operating performances of downhole motor, higher reliability and efficiency.

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Description

The invention relates to the field of electrical engineering, in particular to submersible electric machines, which are used for drives of various underwater mechanisms of drilling and production facilities in the development and extraction of minerals and mineral resources of oil and gas on the seabed, as well as for drives of downhole pumps and drilling mechanisms in exploration and industrial development of the offshore continental shelf for oil and gas production.

Known open-circuit electric machine for working in sea water at any depth of immersion with cooling of the internal active parts of sea water outside (see "Electric machine Vetokhina EMV", patent No. 2072609, BI No. 3, 01/27/97), which contains a stator, a rotor with a shaft and bearings enclosed in an untight housing filled with a liquid cooler, and bearing shields with holes. Sea water was used as a cooler, and the holes in the bearing shields for cold water inlet and heated water outlet were located in two groups. As bearings in this machine, ball bearings of the type U1 and U15 are used from corrosion-resistant stainless steel. The disadvantages of these bearings are: low resource in sea water (500-700 hours), are not designed for vertical execution of the machine.

Of the known closest to the claimed, selected for the prototype, is an electric machine Vetokhin EMV (see. "Electric machine Vetokhin EMV", patent No. 1833703, USSR. 1989). This machine uses thrust plain bearings for electric machines of the EMV type, the liners of which are made of high-density antifriction powder material (cermets), and the movable bushings are made of high-strength, anticorrosive, heat-treated stainless steel of the DI48-VD grade installed on the free ends of the shaft. This machine provides reliable operation as the drive of any underwater mechanism located at an unlimited depth of immersion in sea water with any roll and trim. The disadvantage of this design of EMF for oil wells is the commensurability of the diameter and length of the large rotor in large large-capacity machines, as well as bearings with movable sleeves, structurally impossible to execute in submersible motors for pumps and mechanisms "Burov" for oil and gas wells with a small diameter housing. Submersible motors for oil and gas wells have a small diameter of up to 150 mm, and lengths for large engine capacities reach 8 m, with hydraulic protection up to 16 m, in which the stators, rotors and hydraulic protection are multi-stage. In addition, with a well depth of up to 3,000 m, the temperature of the acidic aggressive formation water reaches 150 ° C, and when drilling to this depth, the drilling axis deviates to 80 °, so plain bearings must be compact, highly loaded and resistant to aggressive formation water when these conditions and to work reliably for a long time with these slopes.

The objective of the invention is to increase the reliability, survivability, durability and energy characteristics of the developed asynchronous machine (AMV NGS) of vertical design with the shaft up for pumps, shaft down for the "Drilling" mechanism to an immersion depth of up to 3000 m and formation water temperature up to 150 ° C in case of deviation from the vertical axis of the machine to 80 ° due to the use of a highly loaded sliding bearing on the side of the non-drive end of the shaft with an insert of high-density antifriction powder material, which ensures alignment of the rotor with the stator bore.

This goal is achieved by the fact that in the well-known vertical asynchronous submersible electric machine with a drive shaft up or down, containing a multi-package stator and a rotor-groove rotor with a monolithic shaft, bearings, one-piece protection of the active parts in the form of rings and bushings of aluminum-magnesium-zinc alloy, enclosed in a housing with holes for the inlet and outlet of the surrounding formation water for cooling, on the non-drive end of the shaft, a thrust plain bearing is made, consisting of a bearing shield, in locked into the housing and secured symmetrically relative to each other with countersunk head screws on the outside of the housing, while a thrust bearing insert made of high-density antifriction powder material (cermet) is pressed into the cylindrical recess of the bearing shield, which is a fixed part of the bearing and having a stubborn and supporting sliding surfaces, and at the end of the shaft a thrust cup with a shoulder made of high-strength anti-corrosion ter treated stainless steel with abutting and supporting sliding surfaces, ground to a grade of 7–10 cleanliness of treatment, while cooling is performed double-sided with the intake of water from the external environment through symmetrical openings in the housing, and water flows directly to the sliding steam through concentric openings in the bearing shield and Clearances between the shaft and the bearing shield.

The invention is illustrated by drawings, in which:

- figure 1 - bearing assembly from the non-drive end of the shaft;

- figure 2. - liner thrust bearing on the side of the non-drive end of the shaft.

Figure 1 shows the bearing assembly from the non-drive end of the shaft, which contains the housing 1, closed by a cover 2, mounted symmetrically located screws 3 with countersunk head on the outside of the housing. A bearing shield 4 is inserted into the housing 1 under locks, fixed on the outside by screws 5 with an M 6 thread and a flush head, symmetrically located relative to each other (6 ÷ 10). A thrust cup 7 made of heat-treated stainless steel 20X13 is pressed onto the end of the shaft 6, which has a shoulder 8 with a thrust sliding surface 9 and a supporting radial sliding surface 10. A thrust sleeve 11 of high-density antifriction powder material is pressed into the cylindrical recess, which is stationary the sliding part of the bearing, which also has a thrust (axial) 9 and a supporting (radial) 10 sliding surface. The sliding abutment surface 9 and the abutment surface 10 of the abutment cup 7 have a grinding accuracy class after heat treatment (7 ÷ 10), and the same sliding surfaces of the insert have a rough machining class and are not polished after machining on a lathe. The insert 11 (Fig. 1, Fig. 2) is made of a powder material with the chemical composition Br05N2S5Gr1DM1 and, after hot stamping and calibration, carries a specific load of up to 120 kgf / cm ² in the axial and radial directions at temperatures up to 300 °, so the working gap of the sliding pair with horizontal and vertical directions there should be a chassis of 60 ÷ 80 microns for a shaft diameter of up to 60 mm. To cool the sliding pairs, there is a free gap 12 between the bearing shield 4 and the thrust cup 7 and through the holes 13 in the bearing shield, through which produced water flows from the cavity of the machine. Formation water enters the cavity of the machine through concentrically located openings 14 in the housing, and through the openings 15, the heated water partially enters the environment, as well as presumably partially fresh cold water enters the environment. The holes 14 and 15 are evenly spaced around the circumference at an angle β relative to each other, the holes of one group 14 relative to the other 15 are offset by an angle β / 2 in order to improve water exchange and to preserve the mechanical strength of the housing. We select 6 holes in each group with a diameter of 5 mm each. To improve cooling of the sliding pair and to remove the formed particles, the liner has axial grooves 16 on the supporting surface and splines 17 on the abutting surface, as a continuation of the grooves, Fig.2. The geometric dimensions of the grooves are 5-6 mm in diameter, and the sectional configuration is semicircle.

To protect against the electrochemical contact corrosion of the bearing assembly and the shaft, a tread sleeve 18 made of ML4 magnesium alloy is pressed onto the shaft 6, having close electrical contact with the thrust cup 7 and the shaft 6, and to protect the housing inside it, a ring 19 is pressed into the end same alloy.

The work of the AMS NHS is as follows. When the engine operates as a pump drive with the shaft end up, the mechanical load from the mass of the rotor and pump and the pump stop will be partially perceived by the thrust sliding surface 9 of the liner 11 after the resource has been thrust by the thrust bearing of the drive end of the shaft. For any deviations of the rotor shaft from the vertical, the bearing surface 10 of the liner 11 will absorb the mechanical load. Since the liner of powder materials has a high specific mechanical load (see above), any deviation of the rotor from the vertical will not affect the alignment of the machine and there will be no increase in working the gap between the stator and the rotor, as a result, the energy characteristics and motor efficiency will remain unchanged. When the engine operates as a “Borax” drive with the shaft downward, the thrust load is absorbed by the thrust bearing of the drive end of the shaft, this bearing does not perceive this load. When the rotor shaft deviates from the vertical, the process of maintaining the coaxiality of the rotor and the stator and maintaining the entire engine structure during operation in the initial state is ensured in both versions by the supporting sliding surface 10.

The claimed technical solution will allow highly reliable operation of the AMV NGS electric motor as a pump drive and a drilling mechanism in oil and gas wells for any deviations of the rotor shaft from the vertical axis. The supporting sliding surface of the liner will ensure that the rotor is aligned with the stator bore and that the working gap between the stator and rotor is constant, as a result, the energy characteristics and motor efficiency are constant, reliability and service life are improved.

Claims (1)

An asynchronous AMV NGS machine of vertical design with a drive end of the shaft up or down, containing a multi-package stator and a rotor-groove rotor with a monolithic shaft, bearings, tread protection of the active parts in the form of bushings and rings of aluminum-magnesium-zinc alloy enclosed in a housing with holes for entry and output of the surrounding formation water for cooling, characterized in that on the non-drive end of the shaft, a thrust plain bearing is made, consisting of a bearing shield inserted under locks in the housing and insulated with symmetrical screws with a countersunk head on the outside of the housing, while a thrust bearing insert made of high-density antifriction powder material (cermet) is pressed into the cylindrical recess of the bearing shield, which is a fixed part of the bearing and having supporting and persistent sliding surfaces, and the end of the shaft is pressed over in a hot seat a thrust cup with a shoulder made of high-strength anti-corrosion heat-treated stainless steel with porous and persistent sliding surfaces polished up to grade 7–10 of the treatment cleanliness, while cooling is performed two-way with water intake from the environment through symmetrical holes in the housing, and water flows directly to the sliding pair through concentric holes in the bearing shield and free gaps between the shaft and bearing shield.

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