RU2321741C1 - Autonomous electric generator - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: autonomous electric generator comprises protecting housing, at least one fastening member, outer rotor provided with the hydraulic turbine and permanent magnets, stator provided with exciting winding and electrical plug, and shaft provided with driving magnets of the magnetic clutch and exciting magnets. The shaft is mounted concentrically to the rotor in three bearings mounted inside it. The driving magnets of magnetic clutch are mounted opposite to the driven magnets inside the rotor.

EFFECT: enhanced power.

5 cl, 3 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 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 ЕВВ 47/022, 47/00, priority from 21.02 .92 g). The lubrication system is a cavity between the rotor and the stator, filled with lubricating fluid.

A self-contained turbine unit (electric generator), also designed to supply electric energy to the telemetry system, containing a hydraulic turbine driven by a wash 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”, M., 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 ° С, 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.

The electric generator according to the patent of the Russian Federation No. 2173925 is also known, 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 by ed. St. RF №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 by ed. 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.

A 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 mounted 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 on the other Torons axis fixed against rotation and having an annular groove for winding and a cylindrical projection which is mounted in the internal bore of the 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.

The tasks of its creation are 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 containing a protective housing and at least one attachment point, an external rotor with a hydraulic turbine and permanent magnets, a stator on which the field winding is installed with an electrical connector, while concentric with the rotor, on three bearings made inside it, a shaft is installed with driven magnets of the magnetic coupling and field magnets, and the driving magnets of the magnetic coupling are mounted against the driven inside the rotor. Hydroturbines are installed side by side in front of the generator. The wires from the winding to the electrical connector pass through the holes made in the stator. The inner cavity of the magnetic coupling is filled with a lubricating fluid, and the inner cavity of the field coil and field magnets is filled with a compensating fluid. The lubricant filling hole is made at the top, and the electrical connector is at the bottom. The electrical connector is coaxial.

The proposed technical solution has novelty, inventive step and industrial applicability, i.e. all the criteria of the invention. The novelty is confirmed by patent research, the inventive step - a new layout of the generator. For the manufacture of all nodes of the electric generator, scarce materials and newly developed technologies are not required, which guarantees industrial applicability.

The invention is illustrated by drawings, where:

figure 1 shows the assembly drawing of an electric generator,

figure 2 shows the design of the shaft,

figure 3 shows the layout of hydraulic turbines.

A stand-alone power generator for supplying downhole equipment is installed in the drill string or in the casing and contains at least one device for attaching the generator 1 to the stator 2. In the device for attaching the generator 1, holes “B” are made for drilling fluid passage.

A stand-alone electric generator contains a rotor 3 with hydraulic turbines 4 and 5. The hydraulic turbine 4 has obliquely mounted flat blades mounted at an angle of 20 ... 45 °, and the blades of the hydraulic turbine 5 are made profiled in order to more effectively operate the pressure drop across the hydraulic turbines, because the execution of both turbines the same would not allow to work on the differential on the second flow turbine 5.

The stator 2 has an electrical connector 6 at the bottom, and an excitation winding 7 is installed inside.

Concentric to the rotor 3 inside it, in front of the autonomous generator, a magnetic coupling 8 is made with a non-magnetic partition 9, on both sides of which are driven magnets 10 and driving magnets 11. A shaft 15 is mounted on three bearings 12, 13 and 14.

Hydroturbines 4 and 5 are installed side by side, at a distance of 2 ... 5 mm from each other in the front of the generator, for a more complete removal of the differential pressure due to the profiling of the turbine blades 5 and 6 with different angles of installation of the blades. Hydroturbine 4 is simultaneously a nozzle apparatus for hydroturbine 5 (figure 3). This allows you to abandon the use of nozzle devices, which will simplify the assembly of the generator and reduce its diametrical dimensions and weight of the generator. Excitation magnets 16 are mounted on the shaft 15 in its lower part. The rotor is sealed relative to the stator 2 by three seals 17, and the relative slip rate along the middle seal is practically zero, which ensures its reliability

The internal cavity of the autonomous electric generator "B" is filled with lubricating fluid. The hole "G" for filling the inner cavity of the generator "G" with lubricating fluid is made in the upper part of the rotor 3 and is closed by a screw 18.

The shaft 15 is made stepwise with a shoulder 19, while the diameter of the steps of the shaft from above to the shoulder 19 increases stepwise, and decreases below the shoulder 19. This is done not only from the conditions of assembly, but also in order to install in the stator the thrust bearing 14 on the step "K" much larger than the radial bearings 12 and 13, which are unloaded from axial loads and are installed on the steps "G" and " And "respectively (figure 2). At the end of the shoulder 19 from the bottom abuts the sleeve 20 (figure 1), which transfers the axial force from the rotor 3 to the thrust bearing 14. The thrust bearing 14 is made closed, filled with grease. The cavity "E" in which the excitation winding 7 and the exciting magnets 16 are located is filled with a compensating liquid. The compensating liquid has a specific volume expansion coefficient equal to the specific volume expansion coefficient of the metal of which the stator is made, while the compensating liquid does not have to have lubricating properties.

The wires 21 from the field winding 7 to the electrical connector 6 pass through the holes "D" made in the stator 2. The electrical connector 6 is made on the lower end of the stator 2 from the bottom and sealed with an elastic compound 22. A filling hole for the compensating liquid is made on the stator 2 in the lower part closed by screw 23.

When the generator is operating, the drilling fluid passes through the hydraulic turbines 4 and 5, which begin to rotate with the rotor 3 and the driving magnets 10.

The magnetic fields generated by the driving magnets 10 pass through a non-magnetic partition 9, drive the driven magnets 11, which rotate with angular velocities corresponding to the rotational speed of the rotor 3.

In this case, the first flow turbine 4 will act as a nozzle apparatus for the second flow turbine 5. This will simplify the assembly of the generator, abandon the use of guide vanes and increase the efficiency and power of the turbine. It also became 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 the design of downhole tools for small diameter drill and casing. The use of wires for the transmission of electrical energy, placed in the holes "E" of the stator 2, will allow you to bring significant power without the use of sliding contacts. The generator with the downhole tool of the 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 not critical, unlike the diameter limit. The diameter of the layout: generator - downhole tool is strictly limited by the diameter of the string. Electricity is transmitted through wires 21 from the field winding 10 to the electrical connector 11. It is preferable to make the electrical connector 6 coaxial, this will make it possible to abandon the angular orientation of the electric generator inside the drill string or casing when it is docked with the downhole tool (Figs. 1 ... 3 downhole tool not shown).

The application of the invention allowed:

1. Significantly reduce the diametrical dimensions and weight of an autonomous electric generator by increasing its length by the length of the magnetic coupling.

2. Increase the power and voltage at the electrical terminals of the generator.

3. Significantly increase the service life of the supports due to the use of three-support schemes, reducing the diameter of all three seals to the minimum possible, ie up to the shaft diameter and minimizing the sliding speed of the middle seal on the shaft relative to the shaft to almost zero.

4. To reduce the imbalance of the rotor of an autonomous generator by reducing their diameter by 1.5 ... 2.0 times.

5. To increase the reliability of sealing the cavity of the generator by separating the oil cavity "B" from the cavity with compensating liquid "E" with a volume coefficient of thermal expansion equal to the volume coefficient of thermal expansion of the metal from which the stator is made, and the failure of the expansion valve, without which Downhole electric generators are usually not used.

6. Simplify the design of the generator by eliminating the use of guide vanes of the turbine and the maximum simplification of the design of the seal.

7. To simplify the assembly and disassembly of the electric generator due to the ego of modular construction and the use of a coaxial electrical connector.

8. Simplify and facilitate electrical wiring, as wires connect the non-rotating field windings to the electrical connector on the stator and pass inside the stator, which eliminates their damage during operation.

9. It will solve the problem of unloading considerable axial force by placing a sealed thrust bearing larger than radial bearings in the stator at the bottom of the autonomous generator, its complete isolation from the housing due to the use of a sealed bearing with grease.

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 (6)

1. An autonomous generator comprising a protective housing and at least one attachment point, an external rotor with a hydraulic turbine and permanent magnets, a stator on which the field winding is mounted, and an electrical connector, concentric with the rotor, on three bearings made inside it, a shaft with driven magnets of the magnetic clutch and field magnets is mounted, and the driving magnets of the magnetic clutch are mounted against the driven ones inside the rotor. 2. The generator according to claim 1, characterized in that the turbines are installed side by side in front of the generator. 3. The generator according to claim 1 or 2, characterized in that the wires from the winding to the electrical connector pass through holes made in the stator. 4. The generator according to claim 1 or 2, characterized in that the inner cavity of the magnetic coupling is filled with a lubricating fluid, and the inner cavity of the field coil and field magnets is filled with a compensating liquid. 5. The generator according to claim 1 or 2, characterized in that the hole for filling the lubricating fluid is made from above, and the electrical connector from below. 6. The generator according to claim 5, characterized in that the electrical connector is made coaxial.

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