RU2419719C1 - Birotary electric generator for power supply to downhole instrument - Google Patents

Abstract

FIELD: electricity. ^ SUBSTANCE: birotary electric generator includes birotary hydraulic turbine having two stages, housing containing the base with attachment assembly. On rear edge of the base there is electric connector, and wires from winding to electric connector pass through the holes made in the base. Sleeve inside which inner rotor with constant magnets is installed on bearings is rigidly fixed on the edge of the base. The first stage of hydraulic turbine if fixed on inner rotor. Outer rotor is installed on bearings on the sleeve; the second stage of hydraulic turbine is fixed on its cylindrical surface, and excitation windings are arranged inside it. Sleeve includes section between constant magnets and excitation windings made of alternating elements made from magnetic permeable and magnetic non-permeable material, and section inside device of noncontact energy transfer from diamagnetic material. At that, between the base and constant magnets there is arranged noncontact energy transfer device containing transmitting and receiving windings arranged on both sides of section of sleeve, which is made from diamagnetic material. Both stages of hydraulic turbine are installed near in front part of turbine. Inner cavity of electric generator is filled with lubricating fluid. On inner rotor from above there is filling opening of lubricating fluid. Electric connector is coaxial. Inside the base there is at least one installed compensator of pressure and thermal expansion. ^ EFFECT: increasing generator power at decreasing diametrical dimensions and weight of generator. ^ 7 cl, 1 dwg

Description

The invention relates to electric machines. Specifically, the invention is intended for a downhole power generator and a downhole telemetry system transmitter. The generator converts the energy of the flushing fluid into electrical energy, which is necessary to power the downhole navigation and geophysical instruments during drilling and the transmitter of the electromagnetic communication channel. For the telemetry system to work at great depths, an increase in the power of the transmitting device to 1 kW or more is required. To get more power with the small dimensions of the generator is very problematic.

A known alternator for powering the telemetric system in the process of drilling small diameter wells, including a fixed internal stator with a collector and an external rotor mounted on the drive shaft, equipped with electromagnets (RF patent No. 2060383, MKP E21B 47/022, 47/00, priority from 21.02 .92). The lubrication system is a cavity between the rotor and the stator, filled with lubricating fluid.

A self-contained turbine unit (electric generator) is also intended for supplying electric energy to the telemetry system, containing a hydroturbine driven by a washing fluid stream, an oil-filled stator filled with an epoxy compound, and a rotor of an alternating current generator with permanent magnets located on the same shaft with a hydraulic turbine ( Molchanov A.A., Siraev A.X. Borehole autonomous systems with magnetic recording (Moscow: Nedra, 1979, pp. 102-103).

This generator consists of a stator located inside the unit and a six-pole annular magnetic rotor made from the outside. The rotor is also a casing for the working blades of a three-stage hydraulic turbine. In front of each stage of the working blades of the hydraulic turbine, in turn, there are three stages of guide vanes assembled on the outer casing, which increases the diameter of the device. To prevent the flushing fluid from entering the generator and the bearing units, sealing devices are installed, the internal cavity of the generator is filled with transformer oil.

Due to the fact that the generator operates in the temperature range from -40 to + 130 ° C, at drilling depths up to 3500 m and more, and the oil volume changes with temperature, a compensator for pressure and thermal expansion of the lubricating fluid (oil) is introduced. The compensator for pressure and thermal expansion of the lubricating fluid is made inside the inlet fairing of the generator. It consists of two thin profile plates, one of which is convex and the other is concave. The compensator for pressure and thermal expansion of the lubricating fluid is designed to compensate for changes in the volume of oil in the oil-filled cavity of the generator under operating conditions with increasing temperature, as well as equalizing the pressure inside and outside the generator.

The disadvantages of this generator are:

- low reliability

- small resource

- large dimensions and mass of the device,

- the complexity of the design.

These shortcomings are caused, first of all, by the fact that a multistage turbine with guide vanes is used as a drive. The use of a hydraulic turbine with guide vanes as a drive places high demands on the quality of cleaning the washing liquid from fractions of drill cuttings and foreign objects, the ingress of which into the gap between the working and guide vanes of the hydraulic turbine can cause it to stop (jamming). The presence of guiding devices of a hydraulic turbine increases the diametrical dimension of the electric generator, which is undesirable when drilling wells of relatively small diameter.

The second design flaw is the complexity and unreliability of the pressure compensator and thermal expansion of the lubricating fluid. Due to the elasticity of the walls of the compensator, the pressure of the lubricating fluid is always less than the pressure of the environment. This can result in flushing fluid entering the generator’s lubrication system and in the wear of bearings, seals and other parts.

Also known generator according to US Pat. RF № 2173925, the main feature of which can be considered a lubrication system. The lubrication system of this generator contains a filling device at its front end, a cavity between the external rotor and the stator, filled with lubricating fluid, and a pressure compensator and thermal expansion of the lubricating fluid located on the side of the generator mounting device, made in the form of a piston mounted with axial movement and seals mounted inside the piston with the possibility of axial movement with it. The disadvantage of this device is the difficulty of filling the system with lubricating fluid and a low seal life.

Known power generator telemetry systems according to St. RF number 34638.

This electric generator contains a filling device in its front part, a cavity between the external rotor and the stator filled with a lubricating fluid, and a compensator for pressure and thermal expansion of the lubricating fluid located on the side of the generator mounting device, made in the form of a piston mounted inside the rotor with axial movement , and the seal, installed, in turn, inside the piston with the possibility of axial movement with it, the piston is made with the possibility of drainage lubricating the fluid in the fully tucked position to the gap between the rotor and the alternator mounting assembly.

The disadvantage of this lubrication system is that due to the combination of the functions of the compensator and the seal, their life is reduced.

Known generator for St. RF № 13123, which contains a rotor with a turbine, a stator, a mounting unit and a reservoir for the reserve supply of lubricating fluid, made in the form of a cup made in the front of the generator with a spring-loaded piston installed inside and a refueling device. The generator and turbine are significantly distant from each other in the axial direction and are separated by a magnetic coupling, which increases the dimensions of the generator and reduces the reliability of the lubricant.

The known generator according to the patent of the Russian Federation for invention No. 2264537, a prototype comprising a housing with field windings, a mount, a rotor with a shaft, magnets and a turbine installed through bearings in the housing, and a reservoir for a reserve supply of lubricating fluid in the form of a cup made in front generator with a spring-loaded piston installed inside and a refueling device, characterized in that at least one front bearing is mounted in a sleeve that is centered in the protruding part of the housing, closed with the other Oron fixed axis of rotation and having an annular groove for winding and a cylindrical boss in the inner bore of which is mounted at least one rear bearing and the inside shaft provided with a through axial aperture. An adjustment washer is installed between the front bearing and the rotor. Field windings are installed in the housing and are fixed with pins against bias. The spring is partially placed inside the piston. The filling device is made in the form of a valve installed in the stem channel, closed by a plug. The filling device is made in the form of a valve installed in the stem channel, closed by a plug.

The disadvantage is the insufficient power of the generator with limited diametrical dimensions due to the low rotor speed.

The task of its creation is to increase power while reducing the diametrical dimensions and weight of the generator.

The solution to this problem was achieved due to the fact that the generator is birotative, containing a biotic turbine, having two stages, a housing containing a base with a mounting unit, an electrical connector is made at the rear end of the base, and wires from the winding to the electrical connector pass through the holes made in the base , a sleeve is rigidly attached to the end face of the base, inside of which an internal rotor with permanent magnets is mounted on the bearings, the first stage of the hydraulic turbine is mounted on the internal rotor, outside the rotor is mounted on bearings on the sleeve, the second stage of the turbine is mounted on its cylindrical surface, the field windings are placed inside, according to the invention, a contactless energy transfer device is placed between the base and the permanent magnets, and the sleeve contains a section between the permanent magnets and the field windings made of alternating elements made of magnetically permeable and magnetically impermeable material and a section inside the contactless energy transfer device from diamagnetic material. Both stages of the turbine are mounted side by side in front of the generator. The non-contact energy transfer device comprises transmitting and receiving windings located on both sides of a portion of a sleeve made of diamagnetic material. The internal cavity of the generator is filled with a lubricating fluid. On the inner rotor, an opening for filling the lubricating fluid is made from above. The electrical connector is coaxial. At least one compensator for pressure and thermal expansion is made inside the base.

The invention is illustrated in the drawings of figures 1 ... 3, where:

figure 1 shows an assembly drawing of a birotative generator,

figure 2 shows a section aa,

figure 3 shows a section bB.

The birotative generator for powering the downhole tool contains a birotative hydraulic turbine 1, having two stages, the first 2 and the second 3, the housing 4, containing the base 5 with the attachment unit 6, an electrical connector 8 is made at the rear end 7 of the base 5, and the wires 9 to the electrical connector 8 through holes 10 made in the base 5 and filled with a compound, a sleeve is rigidly attached to the rear end 7 of the base 5, 11 inside of which an internal rotor 14 with permanent magnets 15 is mounted on bearings 12 and 13. The first stage of hydrotours 2 are mounted on the inner rotor 14. The outer rotor 16 is mounted on bearings 17 and 18 on the sleeve 11. The second stage of the hydraulic turbine 3 is mounted on its cylindrical surface 19, the field windings 20 are located inside the housing 4. Moreover, between the base 5 and the permanent magnets 15 is placed a contactless energy transfer device 21, and the sleeve 11 contains a section 22 between the permanent magnets 15 and the field windings 20, made of alternating elements made of magnetically permeable and magnetically impermeable material, respectively 23 and 24 and a portion 25 inside the device of non-contact transfer of energy from diamagnetic material. Both stages of the turbine 2 and 3 are installed side by side in front of the generator. The contactless energy transfer device 21 comprises transmitting 26 and receiving 27 windings located in a sealed cavity 28 on both sides of a portion of the sleeve 23 made of diamagnetic material. The internal cavity 29 of the generator is filled with a lubricating fluid. On the inner rotor 14, an opening 30 for filling the lubricating fluid closed by a screw 31 is made from above. The electrical connector 8 is made coaxial. At least one pressure and thermal expansion compensator 32 is made inside the base 5, which comprises a piston 33 and an opening 37 communicating the cavity 35 under the piston 33 with the environment. The piston 33 is spring-loaded with a spring 36. The compensator (compensators) 32 is designed to compensate for the temperature expansion of the lubricating fluid, variable ambient pressure and flow rate of the lubricating fluid.

When the generator is working, the drilling fluid passes through the stages of the turbine 2 and 3, which begin to rotate with the rotors 14 and 16 (Fig. 3) in different directions. Permanent magnets 15 rotate and create magnetic fields that pass through alternating elements made of magnetically permeable and magnetically impermeable material, respectively 23 and 24, which do not rotate and intersect the field windings 20, which rotate at angular speeds corresponding to the rotational speed of the outer rotor 16.

In this case, the first downstream stage of the turbine 2 will act as a nozzle apparatus for the second downstream stage of the turbine 3. This will simplify the assembly of the generator, abandon the use of guide vanes and increase the efficiency and power of the turbine. It was also possible to significantly reduce the diametrical dimensions of the generator or increase its power by about 2 times, with the same dimensions and weight. This will allow you to design downhole tools (figure 1 ... 3 is not shown) for drill and casing strings of small diameter. The use of a non-contact energy transfer device, the receiving windings of which are fixed and installed in a sealed cavity, will allow you to output significant power without the use of sliding current collectors. An electric generator with a downhole tool of a downhole telemetry system can be installed in a drill or casing assembled from pipes up to 10 ... 12 m long, i.e. the length limit is uncritical, in contrast to the diameter limit. Layout diameter: generator - downhole tool is strictly limited by the inner diameter of the pipe string.

The application of the invention allowed:

1. Significantly reduce the diametrical dimensions and weight of the electric generator through the use of a biotic turbine and increase its length by the length of the device for contactless energy transfer.

2. To increase the power and voltage at the electrical terminals of the birotative generator through the use of the birotative turbine and the birotative circuit of the generator itself.

3. Significantly increase the service life of bearings through the use of two-bearing circuits for both rotors, reducing the diameter of most seals to the minimum possible, ie up to shaft diameter.

4. To reduce the imbalance of the rotors of the birotational electric generator by reducing the absolute speed by 1.5 ... 2.0 times and reducing the axial dimensions of the rotors.

5. Improve the reliability of the generator by placing the receiving windings of the contactless energy transfer device in a sealed cavity inside the fixed (non-rotating) parts.

6. Simplify the design of the generator by eliminating the use of nozzle devices of the turbine and the maximum simplification of the design of the seal.

7. To simplify the assembly and disassembly of the generator due to its modular design, the rejection of nozzle devices and the use of a coaxial electrical connector.

8. Simplify and facilitate electrical wiring, as wires connect the non-rotating receiving windings of the contactless energy transfer device to the electrical connector made on the rear (lower) end of the base of the case and pass through compound-sealed holes inside the non-rotating parts, which eliminates their damage during operation.

9. Solve the problem of unloading axial force by placing a thrust bearing in a cavity filled with lubricating fluid.

10. Improve the maintainability of an autonomous electric generator due to an extremely simple design, a minimum number of parts and a simple configuration of all parts.

Claims (7)

1. Biotative power generator for powering a downhole tool, comprising a two-stage birotational turbine, a housing containing a base with a mount, an electrical connector is made at the rear end of the base, and wires from the winding to the electrical connector pass through holes made in the base to the end the base is rigidly attached to the sleeve, inside of which the internal rotor with permanent magnets is mounted on the bearings, the first stage of the hydraulic turbine is mounted on the internal rotor, the external rotor is mounted n on bearings on the sleeve, the second stage of the turbine is mounted on its cylindrical surface, the field windings are located inside, characterized in that a contactless energy transfer device is placed between the base and the permanent magnets, and the sleeve contains a section between the permanent magnets and the field windings made of alternating elements, made of magnetically permeable and magnetically impermeable material, and a portion inside the device of non-contact transfer of energy from diamagnetic material. 2. The generator according to claim 1, characterized in that both stages of the turbine are mounted side by side in front of the generator. 3. The generator according to claim 1 or 2, characterized in that the contactless energy transfer device comprises transmitting and receiving windings located on both sides of a portion of the sleeve made of diamagnetic material. 4. The generator according to claim 1 or 2, characterized in that the internal cavity of the generator is filled with a lubricating fluid. 5. The generator according to claim 1 or 2, characterized in that an opening for filling a lubricating fluid is made on top of the inner rotor. 6. The generator according to claim 1 or 2, characterized in that the electrical connector is made coaxial. 7. The generator according to claim 1 or 2, characterized in that at least one pressure compensator and thermal expansion are made inside the base.

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