The invention relates to an electrical power coupler and its application in a wind turbine.

Background of the invention

US6582237 according to its abstract provides a "..full-rotational freedom conductor assembly for conducting electricity between a pair of coaxial electrically conductive members. The conductive members are provided with complementary, planar tracks and are relatively rotatable about a common axis thereof. The invention includes a pair or pairs of opposing coupler halves having a planetary axis, with track- adapted profiles. The pairs of coupler halves are rotatably confined between the tracks enabling electrical contact between the tracks of the conductive members. The invention further includes a force source located at least partially between the coupler halves. The force source applies force to each of the coupling halves in a direction substantially parallel to the second common axis.; The force is applied to the pairs of coupler halves in a manner that enables the coupler halves to be flexibly retained between the tracks.” The assembly relates to large currents. The pairs of coupler halves have a narrow circular gap in between, for instance 0.5 - 1 mm.

In many past applications, mercury was used in transmitting electrical signals from sensors on high speed rotating parts to stationary recording equipment. For instance, see US3317878. In this document, an improved slip ring for high speed operation with means to prevent overheating and contamination of the mercury employed as a conductor between rotating and stationary parts was provided.

US5866967 according to its abstract described: “Magnetic fluid is inserted between slip rings of a rotor and brushes of a stator. The magnetic fluid is held by magnetic force generated by permanent magnets and yokes mounted on the stator, so as to be sidable relative to the slip rings. In this state, in accordance with rotation of the rotor, the baishes and the slip rings are rotated without direct contact with each other via the magnetic fluid. Thus, the brushes and the slip rings are electrically connected to each other.” It uses a colloidal material in which iron powder is dispersed in perfurolocopolyether.

DE102009018655 according to its abstract described '‘The transmitter (2) has two contact rings (3, 5), where a gap (4) is formed between the contact rings and filled with liquid metal. An electric current transmission equalization unit is provided across circumference of the gap. Multiple electrical connections (8) are arranged at the rings over circumference of the rings. One of the rings consists of layers, where one of the layers is limited at the gap, and the other layer is limited at the former layer. The former layer has smaller electrical conductivity than the latter layer, and is made of molybdenum and chromium steel.” This is used for transmitting electrical signals. The “liquid metal” in that publication is defined as follows to be:“Galinstan® is an often silver, eutectic alloy of gallium, indium and tin. Galinstan® is thus an alloy that contains gallium, indium and tin and is suitable as a liquid metal because it is non toxic and remains liquid even at temperatures close to freezing. As the liquid metal, however, mercury or other liquid including, for example, gallium, indium and tin may be used, among other suitable metals.”

Summary of the invention

It is an aspect of the invention to provide an alternative power coupler. In particular, a power coupler which preferably further at least partly obviates one or more of above-described drawbacks.

There is provided an electrical power coupler for electrically coupling a first and second part having a different rotational speed with respect to one another about a power coupler rotational axis, comprising at least one first contact coupled to a first ring and a second contact coupled to a second ring, said first and second ring from an electrically conductive material and functionally concentric, said first and second ring having rotational symmetry axes that functionally coincide with said power coupler rotational axis and said first and second rings rotatable with respect to one another and having a gap between them and which in use is filled with a conductive material that in use allows said first and second ring to rotate with respect to one another and to conduct electrical power from said contact and said second contact.

It was found that the power coupler can be provided in a large current rotary transmitter (LCRT) can be used in large constructions that require large electrical power transmission, like for instance offshore oil & gas constructions in an explosion- prone operating environment. Such an LCRT is in particular used in wind turbines, for instance wind turbines that have an output of between 1 and 20 MW. The current proposal allows a power coupler for transmitting large currents up to for example l,000A per phase, and for voltage levels up to for instance l2kV. It could be deployed with the main rotational axis in either the vertical or horizontal plane, and all intermediate positions within a full 360-degree circle.

The conductive material that is used in the gap in particular comprises a powder, semi-liquid or fully fluid conductive material. In that sense, graphite is also considered a useful conductive fluid. An example is graphite powder sold by Griffon ^® .

In particular, a copper paste can be used. An example is the Marston-Domsel copper paste, which is specified as having the following main characteristics:‘High application temperature range from -30°C to +l300°C, optimum dismantling prerequisites even after long periods of time, high pressure resistance, good electrical conductivity, excellent lubricating and separating effect, prevents cauterisation and seizing up of steel components, excellent heat dissipation, sulphur, lead and nickel- free, very low friction coefficient, extremely adhesive, water and corrosion-resistant, excellent separation and lubrication effect, sealing effect against corrosive gases and liquids.’ A further suitable copper paste is for instance described in US4789411, which is incorporated by reference as if fully set forth. In an embodiment, it can be describes as a high- viscosity grease comprising a high amount of electrically conductive particles, for instance copper or silver. In particular, the amount is at least 80% by volume, more in particular at least 90% by volume. The conductive particles are shaped, in an embodiment irregularly shaped, in order to improve overall electrical conductivity. The particles have an average size smaller than 0.1 mm. In particular, the size is smaller than 0.02 mm. In an embodiment, the particles are also not too small, otherwise it was found that they were surrounded by too much of the grease matrix. In particular, the particles are between 0.01 and 0.1 mm.

Alternative conductive materials could for instance be lithium-based paste, ercury, silver-based, gold-based, aluminum-based (see table)

Table of Resistivity and Conductivity at 20°C

Such an LCRT is well suitable for multiple wind industry and other applications, like in a common high-speed geared wind turbine architecture with Doubly Fed Induction Generator (DFIG), where it could replace the slip ring - brush arrangement. In the above layout, the generator is commonly mounted at a separate generator frame in a semi-horizontal inclined position of say 6-degree backward tilth. The LCRT would be attached to the DFIG shaft at the rear, where‘normally’ the slip ring unit is mounted.

In particular, such an LCRT is further suitable for a counter-rotating generator applied in the applicants drivetrain which comprises two generator rotors instead of one generator-rotor and one stator with conventional generator topologies. This is describes in patent applications NL 2019335, NL 2019518, EP18160789.6.

The electric power or current generated such a counter-rotating generator must therefore be transmitted from a rotating body to a stationary body. The generator part with coils in the current generator layout forms the inner rotor, while the outer rotor contains electro magnets. This generator outer rotor in another arrangement could contain permanent magnets, while in again another alternative arrangement de electrically excited or permanent magnets could be incorporated in the inner rotor and the outer rotor equipped with the coils. Thus, in such a specific counter-rotating generator, there will be a rotating part that needs to be electrically coupled with a stationary part.

In a particular arrangement, the inner part of the power coupler rotatingly coupled to the rotating generator part with the inner part rotating and the outer part stationary. In an alternative arrangement the outer part is rotating and the inner part is stationary.

In an embodiment, the two concentric rings are at substantially the same axial position. In particular, the at least one first ring is functionally coaxially with respect to the at least one second ring.

In an embodiment, the first ring is centred within said second ring.

In an embodiment, the power coupler comprises a series of first contacts and a series of second contacts, each first contact coupled to one first ring and each second contact coupled to one second ring, wherein each time a first and second ring for a pair having said gap, and said pairs are electrically insulated from one another.

In an embodiment, the power coupler further comprising a core having a substantially circle cylindrical shape having a rotation symmetry axis that is functionally coinciding with said power coupler rotational axis, and a circle cylindrical jacket concentrically about said core.

In an embodiment, the core holds said first ring. In an embodiment, the jacket holds said second ring.

In an embodiment, the core comprised at least two core discs. In particular, the at least two core disks are of an insulating material. In a more particular embodiment, the at least two core disks are of an electronically insulating ceramic, an electronically insulating polymer or other insulating material, wherein two subsequent core discs hold a said ring between then.

In an embodiment, the jacket comprises at least two jacket rings, in particular insulating jacket rings, having a second ring between them.

In an embodiment, the jacket rings comprise at least one electrically insulating sealing ring sealing against an outer surface of said core part.

In an embodiment, the core part comprised at least one sealing ring at opposite axial position with respect to each ring, said sealing rings sealing against said inner surface of said jacket, in particular for defining ring-shaped chambers in fluid communication with said gap.

In an embodiment, the first and second ring provide facing ring surfaces having a surface area of one ring of facing rings is at least 10 cm ² In particular, the facing ring surface of one ring is at least 300 cm ² . In an embodiment, the surface area is less than 1 m ² .

In an embodiment, the gap having a distance between said facing ring surfaces of less than 2 mm, in particular said gap provides a spacing of 0.05-1 mm. between nearest surfaces of said first and second ring, in particular 0.3 - 1 mm.

In an embodiment, the surfaces of the facing rings are smooth. In an embodiment, the surfaces have been grinded, having a surface smoothness of between 0.1-1.6 micron. It can have an average of 0.4 micron. In a particular embodiment, the surface smoothness results from polishing. In particular, such a surface smoothness is between 0.1 and 0.4 micron. The average is in such a case about 0.2 micron.

A smooth surface in combination with a viscous and adhesive grease between smooth surfaces results in internally building a hydrodynamic pressure on the conductive material when the surfaces move with respect to one another.

In an embodiment, the conductive material is selected from cupper paste, lithium past, silver past, aluminium past, gold paste, and a combination thereof.

In an embodiment, in use said at least one first ring rotates and said at least one second ring is stationary. In an embodiment, in use said at least one second ring rotates and said at least one first ring is stationary.

In a specific arrangement, only one of the parts, either with shared horizontal, vertical or shared intermediate rotational axis, is rotatingly driven and the second stationary part with a narrow gap (for example 0.05 - 0.3mm) in between. This gap is filled with copper paste or another highly conductive metal particles filled paste characterized by extreme stickiness creating a strong adhesive force to the rings (example description Domsel-Marston). This conductive paste consists of metal or other highly conductive particles incorporated in a (compressible) matrix of bonding grease material. During rotation of the inner or outer ring part relative to each other, the available space for the conductive paste in between the rings is in the radial plane confined by the ring spacing gap. At the concentric inner and outer surfaces the paste sticks to the rings by strong adhesive force. The radial confinement and strong adhesive forces combined builds up strong hydrodynamic pressure along the full rings circumference and this induces a strong conductivity between the two parts rotating relative to each other. The physics‘mechanism’ is that the metal or other highly conductive particles in the paste are temporarily pushed out of the grease matrix and against each other. The physical operating principle as a phenomenon could be described as‘Adhesion-enhanced hydrodynamic circumferential pressure building in between two or more rotatingly coupled narrow-gap concentric rings.’

The phenomenon bears some physical resemblance with the hydrodynamic pressure build-up in journal bearings, but in journal bearings oil is used instead of ‘sticky grease’ containing metal or other electrically conductive particles, and the adhesion-enhanced hydrodynamic pressure building component is absent.

In another specific arrangement, again only one of the parts, either with shared horizontal, vertical or shared intermediate rotational axis, is rotatingly driven. But there is now an extra‘free-floating’ ring placed in between the first rotatingly driven and the second stationary part, and there are therefore two narrow gaps (for example 0.05 - 0.3mm) in between. The ‘free-floating’ ring will rotate at intermediate equilibrium speeds in between‘0’ (stationary part) and continuously varying generator speeds for example 0 - 2000 RPM). These‘free-floating’ ring speeds are a function of the continuous changing relative speeds between the stationary part and the part running at generator speed and continuously adjust themselves to a new equilibrium. The two converging gaps are again filled with copper paste or another highly conductive metal particles filled paste characterized by extreme stickiness creating a strong adhesive force to the rings (example description Domsel-Marston). This conductive paste consists of metal or other highly conductive particles incorporated in a (compressible) matrix of bonding grease material. During rotation of the ring pairs relative to each other, the available space for the conductive paste in between the rings is in the radial plane confined by the ring spacing gap. At the concentric inner and outer surfaces the paste sticks to the polished or otherwise very smooth ring surfaces by strong adhesive force. The radial confinement and strong adhesive forces combined builds up strong hydrodynamic pressure along the full rings circumference and induces a strong conductivity between the two parts rotating relative to each other. The physics ‘mechanism’ is that the metal or other highly conductive particles in the paste with specific irregular or regular shapes, are temporarily pushed out partly of completely of the grease matrix and against each other. The physical operating principle as a phenomenon could be described as‘Adhesion-enhanced hydrodynamic circumferential pressure building in between two or more rotatingly coupled narrow-gap concentric rings.’

The phenomenon bears some physical resemblance with the hydrodynamic pressure build-up in journal bearings. The above arrangement with an extra‘free- floating ring as main benefits offer a much larger contact area for the conductive paste for given system dimensions, the system likely runs cooler, and lifetime of the conductive paste is expected much enhanced.

In an embodiment, the power coupler further comprising a cooling mantle provided around the outer part and/or also inside the power coupler, in particular comprising a closed cooling air circuit, an air-air or air-liquid heat exchanger, and more in particular a temperature control strategy based upon regulating air volume and air velocity through said power coupler.

In an embodiment, the power coupler further comprising an insulating disk between each pair of a said first ring and a said second ring for providing an additional electrical barrier, in particular against high-voltage‘phase bridging’.

In an embodiment, the conductive material for in use filling said gap is selected from a low-friction powder-type conductive material, a semi-liquid conductive material, a liquid conductive material, a conductive paste, and a combination thereof. In an embodiment, the power coupler is provided for coupling an at least two phase electrical power, wherein each phase is coupled to a separate first ring. In an embodiment, the power coupled comprises three first rings and three corresponding rings for coupling a three-phase current.

The invention further pertains to an electrical power coupler for electrically coupling a first and second part having a different rotational speed with respect to one another about a rotational axis, said electrical power coupler comprising at least one first contact electrically coupled to a first ring and a second contact electrically coupled to a second ring, said first ring and said second ring concentric with respect to said rotational axis, said first and second ring having a mutual spacing, said first ring held in a substantially circle cylindrical core of an electrically insulating material which is coaxially with respect to said rotational axis, said second ring held in a substantially circle cylindrical jacket and which is coaxially with respect to said rotational axis, said circle cylindrical core and said circle cylindrical jacket rotatable with respect to one another with respect to said rotational axis, at least one of said circle cylindrical core and said circle cylindrical jacket holding a first and second sealing at an axial distance from one another and at axially opposite distance from said first and second ring, said mutual spacing and an axial spacing between said first and second sealing and a spacing between said circle cylindrical core and said circle cylindrical jacket defining a circular chamber for in use holding an electrically conductive fluid for electrically coupling said first and second ring.

There is further provided an electrical power coupler for electrically coupling a first and second part having a different rotational speed with respect to one another about a power coupler rotational axis, comprising at least one first contact coupled to a first ring and a second contact coupled to a second ring, said first and second ring from an electrically conductive material and functionally concentric, said first and second ring having rotational symmetry axes that functionally coincide with said power coupler rotational axis and said first and second rings rotatable with respect to one another and having a gap between them and which in use is filled with a conductive material that in use allows said first and second ring to rotate with respect to one another and to conduct electrical power from said contact and said second contact. The invention further pertains to an onshore wind turbine architecture comprising said electrical power coupler.

The invention further pertains to an offshore installation comprising said electrical power coupler.

The term“substantially” herein, such as in“substantially all emission” or in “substantially consists”, will be understood by the person skilled in the art. The term “substantially” may also include embodiments with“entirely”,“completely”,“all”, etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term“substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term“comprise” includes also embodiments wherein the term“comprises” means“consists of’.

The term "functionally" will be understood by, and be clear to, a person skilled in the art. The term “substantially” as well as “functionally” may also include embodiments with“entirely”,“completely”,“all”, etc. Hence, in embodiments the adjective functionally may also be removed. When used, for instance in“functionally parallel”, a skilled person will understand that the adjective“functionally” includes the term substantially as explained above. Functionally in particular is to be understood to include a configuration of features that allows these features to function as if the adjective“functionally” was not present. The term“functionally” is intended to cover variations in the feature to which it refers, and which variations are such that in the functional use of the feature, possibly in combination with other features it relates to in the invention, that combination of features is able to operate or function. For instance, if an antenna is functionally coupled or functionally connected to a communication device, received electromagnetic signals that are receives by the antenna can be used by the communication device. The word “functionally” as for instance used in “functionally parallel” is used to cover exactly parallel, but also the embodiments that are covered by the word“substantially” explained above. For instance,“functionally parallel” relates to embodiments that in operation function as if the parts are for instance parallel. This covers embodiments for which it is clear to a skilled person that it operates within its intended field of use as if it were parallel.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The devices or apparatus herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation. This includes for instance an alternative arrangement for conventional generators in wind turbines like a replacement of the traditional slip ring-brush unit mounted at the generator shaft rear.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The invention further applies to an apparatus or device comprising one or more of the characterising features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterising features described in the description and/or shown in the attached drawings.

The various aspects discussed in this patent can be combined in order to provide additional advantages. Furthermore, some of the features can form the basis for one or more divisional applications.

Brief description of the drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: Figure 1 schematically depicts an perspective view, having a pie part cut away, of an embodiment of the power coupler, and

Figure 2 a cross section of the power coupler of figure 1.

The drawings are not necessarily on scale

Description of preferred embodiments

Figure 1 schematically depicts an perspective view, having a pie part cut away, of an embodiment of the power coupler 1, and figure 2 a cross section of the power coupler 1 similar to figure 1.

The power coupler 1 comprises a series of first contacts 2, 2’, 2”, and a series of second contacts 4, 4’, 4”. The power coupler electrically couples these respective contacts for providing an electrical connection between contact 2 and 4, 2’ and 4’, and 2” and 4”. The first contacts 2, 2’, 2” are coupled to a first part of for instance a wind turbine, and the second contacts 4, 4’, 4” are coupled to a second part of this wind turbine. The first and second part can rotate with respect to one another around a rotational axis R. Usually, large electrical currents can be transmitted, for instance up to 500 - 1500A per contact and 750V - !3.8kV generator voltage level.

The power coupler 1 comprises a series of first rings 3, 3’ and 3”. Each of these first rings 3, 3’, 3”, is coupled to a respective first contact 2 2’, 2”. The power coupler further comprises a series of second rings 5, 5’, 5”. Each of these second rings 5, 5’, 5” is coupled to a respective second contact 4, 4’, 4”. Each of the first rings 3, 3’, 3”, is concentrically with respect to a respective second ring 5, 5’, 5”. Each first ring 3, 3’, 3” and second ring 5, 5’, 5” comprises a gap G between them. In operation, this gap G is substantially filled with a conductive material that allows the rings to rotate with respect to one another around their rotational axes which coincides with power coupler rotational axis R.

In the current embodiment, each first rings 3, 3’, 3” are centered within respective second rings 5, 5’, 5”.

In figures 1 and 2, the power coupler 1 comprises a core 6 and a jacket 7. The core and jacket are rotatable with respect to one another around the power coupler rotational axis R. In the current embodiment, the first rings 3, 3’, 3” are held in the core 6, and the second rings 5, 5’, 5” are held in the jacket 7. For a simple and efficient construction, the core 6 comprises a series of core cylinders 8-8’”. In an embodiment, two core cylinders 8-8”’ hold a first ring 3, 3’, 3” between then. The core cylinders can be made from an insulating material. For instance, a high-performance insulating ceramic or polymer material can be used. In the embodiment of figure 1, the core cylinders 8-8’” are held together using a series of core mounting bars 19. In the embodiments of figure 1 and 2, the first contacts 2, 2’, 2” each comprises an axial lead that connects to one of the respective first rings 3, 3’, 3”. The axial leads run though the core 6. The axial leads can comprise lead ends incorporated in core cylinders 8-8”’.

For easy construction, the jacket 7 comprises a series of jacket rings 9. These jacket rings 9 are stacked and hold second rings 5, 5’, 5”. In the illustrated embodiment, the jacket rings 9 are identical. The jacket rings 9 are in an embodiment substantially made from an electrically insulating material.

Each set of one of the first rings 3, 3’, 3” and one of the corresponding second rings 5, 5’, 5” is electrically separated from one another through sealing rings 10, 11 between the core 6 and jacket 7.

Insulating disks are provided between each set of a first and second ring, The insulating disks 15 are made of a high-performance electrically insulating material and their main function is creating an electrical barrier against high-voltage leaks between the individual sets of rings. Each set of rings can for instance be coupled to a different electrical phase.

The jacket 7 comprises an upper disk 12 which in the current embodiment rests on the core 6 via a bearing 18. This construction simplified the construction.

In the embodiment of figures 1 and 2, the upper disk 12 radially extends from the jacket 7, and the jacket 7 further comprises a lower disk 13 which also radially extends from the jacket 7. The upper and lower disks 12, 13 are connected via a cooling jacket 14, to provide a cylindrical cooling space between the jacket 7 and cooling jacket 14. The cooling jacket 44 comprises a cooling fluid inlet 16 and a cooling fluid outlet 17. In this embodiment, the cooling fluid is air.

The cooling air circulates in a closed circuit (not impacted by the harsh marine environment). The air flow passes through an air/air or air- water heat exchanger with an air flow controlled or alternative control strategy for precise internal LCRT temperature management during all operating conditions including full load. This can be in individual cooling arrangement, or be integrated with the turbine cooling system. In the current embodiment, each second ring 5, 5’, 5” comprises a channel 20 which couples the radial outer surface and the radial inner surface and is coupled to a source of conductive material. The channel is in communication with the gap G and allows (keeping) the gap G and in the current embodiment conductive fluid chamber to be fluidly coupled to the source of conductive fluid.

Each first ring 3, 3’, 3” and second ring 5, 5’, 5” provide facing surfaces that partly bound the gap G. These facing surfaces have an area which are here defined by D x 2 x Rr x p, with D the (axial) thickness of the first and second rings (which here almost correspond) and Rr the outer radius or the first rings which almost corresponds to the inner radius of the second rings. The relative large surface area reduces the current and heat built-up per amount of area. The first and second rings are usually from a conductive material, for instance copper.

Currently, there are five specific embodiments that may be considered for electrically coupling said first and second ring or firs and second rings in ring pairs.

Below, several embodiments for electrically coupling the first ring and second ring are discussed. These embodiments may be combined.

Option 1 - Conventional slip ring and brushes.

Electrical power is coupled to one or more first rings via one or more brushes. In case of electrical power in several phases, each electric phase (for instance three in total) is coupled to one first ring and is coupled via at least one brush unit per first ring.

Option 2 - Concentric rings with minimal vertical air gap.

Electric generator current (for instance three phases) is transmitted from individual inner first rings to a matching second rings via a minimal air gap and with the aid of an electrical conductive powder (graphite), semi-liquid (copper paste) or liquid that (completely) fills the gap.

Option 3 - Concentric rings with minimal air gap in inclined position (relative to a horizontal plane, or a plane that is normal to the rotational axis of the power coupler)

Electric generator current (e.g., three phases) is transmitted from individual inner rotating inclined first rings to a matching stationary opposed second ring s via a minimal air gap and with the aid of an electrical conductive powder (graphite), semi liquid (copper paste) or liquid that (completely) fills the gap.

Option 4 - Concentric rings with multiple V-shaped rollers. Electric generator current (e.g., three phases) is transmitted from individual inner rotating inclined first rings to a matching opposed second rings with the aid of V- shaped rollers equally interspaced and incorporated in a roller cage. In an embodiment, a spiral spring incorporated in the stationary outer housing provides adequate pressure to the rollers for ensuring efficient current transmission. In a further embodiment, an electrically conductive powder (e.g., graphite), an electrically conductive semi-liquid (e.g., copper paste) or electrically conductive liquid with additional excellent lubrication characteristics enhances electric power transmission and ensures adequate lubrication and long service life of all moving components and surfaces.

Option 5 - Silver-fibre brushes and silver-lined copper ring

Generator power induced is coupled to one or more first rings and silver-fibre baishes. Each electric phase (three in total) contains one first ring and at least one brush unit per first ring. The individual metal fibres are very thin and could be described as a‘wire brush’ containing wires of a specific metal alloy with silver coating. The copper first rings are also silver coated, and due to the relative movement of the brushes at the silver-lined first ring, the latter surface becomes patinated and shiny. Once this stage is reached, further wear stops and optimal silver-silver contact between brushes and first ring is ensured.

It will also be clear that the above description and drawings are included to illustrate some embodiments of the invention, and not to limit the scope of protection. Starting from this disclosure, many more embodiments will be evident to a skilled person. These embodiments are within the scope of protection and the essence of this invention and are obvious combinations of prior art techniques and the disclosure of this patent.

Reference Numbers

1. Power coupler

2. First contact

3. First ring

4. Second contact

5. Second ring

6. Core

7. Jacket

8. Core cylinder

9. Jacket ring

10. Sealing ring

11. Further sealing ring

12. Upper disc

13. Lower disc

14. Cooling jacket

15. Insulating disk

16. Cooling inlet

17. Cooling outlet

18. Bearing

19. Core mounting bar

20. Conductive material inlet

R power coupler rotational axis G gap between first and second ring