RU2337240C1 - Downhole electric generator - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: downhole electric generator contains fixing unit, rotor with hydraulic turbine impeller installed in the top part of electric generator, and permanent magnets installed in it, stator, in which excitation winding is installed. At that in bottom part of electric generator on rotor the second impeller of hydraulic turbine is installed. Nozzle block of hydraulic turbine is arranged inside fixing unit. Fixing unit is located in stator middle part.

EFFECT: increase of generator power with reduction of diametrical dimensions and weight of generator.

2 dwg

Description

The invention relates to electric machines. Specifically, the invention is intended for a power generator for supplying downhole equipment and a transmission device for a downhole telemetry system. An electric generator converts the energy of the flushing fluid into electrical energy, which is necessary for supplying 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 power the telemetry system, contains 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.Kh., “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.

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 device, a filling device at its front end, a cavity between the external rotor and the stator filled with a 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 the possibility of 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 №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 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 protrusion in the inner bore of which is mounted on 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 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 electric generator.

The solution of these problems was achieved in a borehole electric generator containing a mounting unit mounted on the upper and lower bearings, a rotor with a turbine impeller installed in the upper part of the electric generator, and permanent magnets mounted on it, and a stator on which the field winding is installed, characterized in that in the lower part of the generator on the rotor is installed a second impeller of the turbine, and the impeller of the turbine installed in the upper part of the generator has the installed flat blades installed at an angle of 20-45 °, and the blades of the second impeller of the hydraulic turbine installed in the lower part of the generator are made with the opposite angle of inclination, while the mount is made in the middle of the stator and the nozzle of the turbine is made inside it, and the lower bearing is made thrust and perceives axial load through the sleeve.

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 in the drawings, figures 1 and 2, where:

figure 1 shows the assembly drawing of a downhole generator,

figure 2 shows the location of the impellers of a hydraulic turbine.

The downhole electric generator (Fig. 1), designed to supply downhole equipment, is installed in the drill pipe string or in the casing and holds the fastener 1 on the stator 2. In the fastener 1 holes are made for the passage of the drilling fluid.

The downhole electric generator comprises a rotor 3 with an upper impeller of a hydraulic turbine 4 and a lower impeller of a hydraulic turbine 5, i.e. the turbine is made in two stages. The upper impeller of a hydraulic turbine 4 has obliquely mounted flat blades mounted at an angle of 20 ... 45 °, and the blades of the lower impeller of a hydraulic turbine 5 are made with the opposite angle of inclination in order to more efficiently operate the pressure drop across the impellers of the hydraulic turbine, because the execution of the two impellers of the hydraulic turbine with the same would not allow the differential pressure to operate on the second downstream lower wheel of the hydraulic turbine 5. To significantly increase the efficiency of the downhole electric generator inside the mount 1, a nozzle apparatus 6 was made.

An excitation winding 7 is installed on the stator 2 in the inner cavity of the borehole electric generator B. Permanent magnets 8 are installed on the rotor 3. The rotor 3 is mounted on bearings: upper 9 and lower 10, while the lower bearing 10 is made resistant and accepts axial load through the sleeve 11.

The internal cavity of the generator B is filled with a lubricating fluid. The lubricant of the cavity B is filled with oil through the channel B, closed during operation with the screw 12. The bearings 9 and 10 are protected by seals 13.

During operation of the downhole electric generator, the drilling fluid passes through hydraulic turbines 4 and 5, which begin to rotate with the rotor 3. Permanent magnets 7 create a rotating magnetic field, due to which an electric current arises in the field coil 9.

The implementation of the nozzle apparatus 6 inside the mount 1 will simplify the assembly of the generator. It also became possible to significantly reduce the diametrical dimensions of the generator or increase its power by 2 times with the same dimensions and weight. This will allow the design of downhole tools for small diameter drill and casing.

The application of the invention allowed:

1. Significantly reduce the diametrical dimensions and weight of the downhole electric generator through the use of a two-stage hydraulic turbine.

2. Increase the power and voltage at the electrical terminals of the generator through the use of a two-stage hydraulic turbine.

3. To reduce the imbalance of the rotor of the downhole electric generator by reducing their diameter by 1.5 ... 2.0 times.

4. To increase the reliability of the seal cavity of the downhole generator by reducing the diameter of its seals.

5. To simplify the design of the birobotative electric generator, through the use of only one nozzle apparatus of the turbine, its installation inside the mount, and the maximum simplification of the design of all nodes.

6. To simplify the maintainability of the downhole electric generator due to the extremely simple design, the minimum number of parts and the simple configuration of all parts.

Claims (1)

A downhole electric generator comprising a mounting unit, a rotor mounted on the upper and lower bearings with a hydraulic turbine impeller mounted on the upper part of the electric generator and permanent magnets mounted on it, and a stator on which the field winding is installed, characterized in that the lower part of the electric generator has the rotor has a second impeller of the turbine, and the impeller of the turbine installed in the upper part of the generator has obliquely mounted flat blades, set mounted at an angle of 20-45 °, and the blades of the second impeller of a hydraulic turbine installed in the lower part of the electric generator are made with the opposite angle of inclination, while the mounting unit is made in the middle of the stator and the nozzle apparatus of the hydraulic turbine is made inside it, and the lower bearing is made resistant and perceives axial load through the sleeve.

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