WO2011104506A2

WO2011104506A2 - Improved wind turbine with adaptable rotor

Info

Publication number: WO2011104506A2
Application number: PCT/GB2011/000252
Authority: WO
Inventors: Wolf Dietrich
Original assignee: The City University
Priority date: 2010-02-23
Filing date: 2011-02-23
Publication date: 2011-09-01
Also published as: WO2011104506A3; GB201003033D0

Abstract

The present invention relates to apparatus for mounting a wind turbine on a support mast, the apparatus comprising an inner sleeve member arranged to be disposed around the support mast; an outer sleeve member arranged to support the wind turbine, the outer sleeve member being concentrically mounted around the inner sleeve member; and wherein the outer sleeve member is arranged to be rotatable relative to the inner sleeve member.

Description

Improved Wind Turbine With Adaptable Rotor

Field of Invention

The invention methods and apparatus for improving wind turbines. In particular, the present invention relates to apparatus for mounting a wind turbine on a support mast.

Background of the invention

There is a growing demand for alternative, environmentally friendly renewable energy generation means. In part, this is as a result of increased awareness of the negative environmental impacts associated with traditional energy generation means. Equally, it is generally accepted that as the resources traditional energy generation means are reliant on (e.g. fossil fuels, nuclear fuels, etc.) become ever more limited, a migration to renewable energy sources is inevitable. In view of such considerations, many governments have already actively adopted and incorporated long term renewable energy migration plans into current energy policy, with the objective of gradually decreasing reliance on traditional non-renewable energy sources. Such policies advocate replacing traditional energy sources with renewable energy sources. However, to achieve the desired objective and to meet expected energy demands, improved and more efficient renewable energy generation means are required.

There are a plurality of renewable energy sources, which may be harnessed. Wind is one such example, which depending on geographic location may provide a tangible alternative to traditional non-renewable energy sources. Wind turbines exist in various sizes, from very large utility scale models for on-shore and off-shore installations with rotors measuring 60m and more in diameter, down to small turbines with rotor sizes of less than lm.

Typically, small wind turbines for domestic, industrial, agricultural and communal use, are designed for micro-generation of electricity at or near the point of use and are typically installed close to dwellings.

Such wind turbines provide higher energy efficiency if they are mounted on freestanding or guy- wired masts, which allow the rotor of the turbine to sit in an elevated position over surrounding obstacles to the wind, such as buildings and other man-made structures and natural obstacles such as trees or ground elevations. Therefore installation on a mast - as opposed to installation, for example, on a rooftop - is a preferred option.

The mast solutions currently offered by manufacturers of such wind turbines are either freestanding or guy-wired masts. A common feature to all of these solutions is that the wind turbine rotor and generator assembly is mounted on top of the mast, rotating on a shaft which is aligned with the mast centre.

Conventional small wind turbine designs - small referring to the aforementioned turbines for domestic, industrial, agricultural and communal use that are too small to support internal or external climbing ladders in or on their masts - require lowering to the ground of the complete mast-turbine rotor assembly, for maintenance and/ or repair. In the prior art, this is commonly achieved through the use of a hinge at or near the base of the mast. Additionally, lifting aids such as portable winches in combination with a rope and a gin pole or a hydraulic system are required to lower the mast. All known prior art solutions require lifting aids, trained and experienced operators, and a ground clearance equivalent to the height of the mast including the wind turbine-rotor and generator assembly installed on top of the mast. These requirements have a considerable impact on the required time and cost of accessing the wind turbine rotor and generator unit for maintenance and/or repair, in addition to limiting the locations where such wind turbines may be used. In particular, such wind turbine design solutions are not viable in densely populated urban areas, where there often is not the sufficient cleared area to enable lowering of the mast.

Furthermore, such known prior art solutions are not economically viable for lone users, where the maintenance costs are too high to be born by the lone user.

It is an objective of the present invention to provide an improved wind turbine rotor generator mast assembly, designed to address the shortcomings of the a bove discussed prior art solutions, and specifically to provide a design which facilitates maintenance.

Summary of Invention

The present invention relates to an improved wind turbine rotor-generator apparatus. In particular, a first aspect of the present invention relates to appa ratus for mounting a wind turbine on a support mast, the apparatus comprising: an inner sleeve member arranged to be disposed around the support mast; an outer sleeve member arranged to support the wind turbine, the outer sleeve member being concentrically mounted around the inner sleeve member. The outer sleeve member is arranged to be rotatable relative to the inner sleeve member.

Preferably, the inner sleeve member and the outer sleeve member define a longitudinal axis of rotation parallel to the length of the support mast, and the outer sleeve member is arranged to be rotatable about the longitudinal axis.

An advantage provided by the apparatus when mounted on a support mast of a wind turbine, is that it enables rotation about the longitudinal axis of the support mast, such that the turbine may be oriented in accordance with a predominant wind position.

The apparatus may further comprise a rotation means arranged to enable rotation of the outer sleeve member relative to the inner sleeve member.

The rotation means may comprise one or more wheels disposed between the inner sleeve member and the outer sleeve member, the wheels being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the longitudinal axis.

The rotation means may comprise one or more bearings disposed between the inner sleeve member and the outer sleeve member, the bearings being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the longitudinal axis.

The rotation means may comprise one or more sliders disposed between the inner sleeve member and the outer sleeve member, the one or more sliders being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the longitudinal axis. The apparatus may comprise an electronic control system operatively coupled to the rotation means, arranged to activate the rotation means for rotating the outer sleeve member relative to the inner sleeve member.

Preferably the apparatus comprises guide means arranged to constrain motion of the inner sleeve member in a longitudinal direction relative to the outer sleeve member. Advantageously, this enables the longitudinal height of the apparatus to be varied when mounted on a support mast of a wind turbine, thus facilitating servicing and maintenance.

The guide means may comprise one or more wheels fitted to the inner sleeve member between the sleeve member and the support mast, arranged to rotate in the longitudinal direction.

The guide means may comprise one or more sliders fitted to the inner sleeve member, arranged to enable movement in the longitudinal direction when coupled to one or more guide rails disposed on the support mast.

Preferably the outer sleeve member is freely rotatable relative to the inner sleeve member, thereby facilitating rotation of the outer sleeve member.

The apparatus may further comprise longitudinal position varying means coupled to the inner sleeve member, arranged to vary the longitudinal position of the inner sleeve member relative to the support mast.

The longitudinal position varying means may comprise a winch coupled to the inner sleeve member via a tether, the winch being arranged to vary the longitudinal position of the inner sleeve member relative to the support mast, by varying the tether length. The winch may be disposed within the support mast. Advantageously, the support mast provides the functionality of a protective housing, protecting the winch from any external sources which may compromise its functionality.

The winch may be electronically activated.

Alternatively, the winch may be manually activated.

The winch may be operatively coupled to a control system, and operation of the winch may be activated by the control system to vary the longitudinal position of the inner sleeve member relative to the support mast. The control system facilitates the varying of the longitudinal position.

The control system may be arranged to activate the winch to lower the inner sleeve member's longitudinal position relative to the support mast, when wind conditions exceed a predetermined threshold value. An advantage associated with this features is that the likelihood of any damage being caused to the apparatus due to extreme wind conditions may be minimised.

The apparatus may comprise locking means arranged to maintain the inner sleeve member in a fixed longitudinal position relative to the support mast.

Advantageously, the apparatus may comprise braking means operatively coupled to the tether, arranged to have a first position when the tether is in tension, and a second position when the tether is not in tension; and wherein the braking means is arranged to constrain the longitudinal motion of the inner sleeve member relative to the support mast, when in the second position, such that in the event of a rupture in the tether, movement of the apparatus in the longitudinal direction may be constrained to minimise the risk of damage to the apparatus. The apparatus may comprise a wind turbine fitted to the outer sleeve member. An advantage of fitting a wind turbine to the outer sleeve member is that the wind turbine may align itself with the prevailing wind direction.

The apparatus may comprise an electric generator fitted to the outer sleeve member.

A second aspect of the present invention relates to a wind turbine comprising a support mast; a turbine; and rotation means. The rotation means comprising an inner sleeve member disposed around the support mast; an outer sleeve member concentrically mounted around the inner sleeve member, the outer sleeve member being arranged to be rotatable relative to the inner sleeve member, and having a longitudinal axis of rotation; and wherein the turbine is disposed on the outer sleeve member.

The rotation means may comprise one or more wheels disposed between the inner sleeve member and the outer sleeve member, the wheels being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the axis of rotation.

The rotation means may comprise one or more bearings disposed between the inner sleeve member and the outer sleeve member, the bearings being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the axis of rotation.

The rotation means may comprise one or more sliders disposed between the inner sleeve member and the outer sleeve member, the one or more sliders being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the axis of rotation.

The wind turbine may comprise an electronic control system operatively coupled to the rotation means, arranged to activate the rotation means for rotating the outer sleeve member relative to the inner sleeve member. In this way the orientation of the wind turbine may be aligned with a predominant wind direction. The wind turbine may comprise guide means arranged to constrain motion of the inner sleeve member in a longitudinal direction relative to the outer sleeve member.

The guide means may comprise one or more wheels disposed between the inner sleeve member and the support mast, arranged to rotate in the longitudinal direction. Advantageously, this facilitates lowering and raising the rotor in the longitudinal direction, for example for servicing and/or maintenance.

The guide means may comprise one or more sliders fitted to the inner sleeve member; one or more guide rails disposed in a longitudinal orientation along the support mast; and wherein the one or more sliders are coupled to the one or more guide rails enabling longitudinal displacement of the inner sleeve member along the support mast. The guide rails and coupled sliders ensure that motion of the inner sleeve member is constrained in the longitudinal direction, thereby facilitating the lowering and raising of the turbine.

The wind turbine may comprise longitudinal position varying means coupled to the inner sleeve member, arranged to vary the longitudinal position of the inner sleeve member relative to the support mast. An advantage provided by this feature is that the longitudinal position of the turbine may be varied along the length of the support mast.

The longitudinal position varying means may comprise a winch coupled to the inner sleeve member via a tether, the winch being arranged to vary the longitudinal position of the inner sleeve member relative to the support mast, by varying the tether length.

The winch may be disposed within the support mast, the mast providing a protective casing for the winch. The winch may be electronically activated.

The winch may be manually activated.

The winch may be operatively coupled to a control system, and operation of the winch may be activated by the control system to vary the longitudinal position of the inner sleeve member relative to the support mast.

The control system may be arranged to activate the winch to lower the inner sleeve member's longitudinal position relative to the support mast, when wind conditions exceed a predetermined threshold value, thereby protecting the rotor and minimising the likelihood of the rotor rupturing due to high wind speeds.

Advantageously, the wind turbine may comprise locking means arranged to maintain the inner sleeve member in a fixed longitudinal position relative to the support mast.

The wind turbine may comprise braking means operatively coupled to the tether, arranged to have a first position when the tether is in tension, and a second position when the tether is not in tension; and wherein the braking means may be arranged to constrain the longitudinal motion of the inner sleeve member relative to the support mast, when in the second position, thus providing a safety mechanism to minimise the risk of damage to the rotor in the event of a ruptured tether.

The wind turbine may comprises one or more blades having a horizontal axis of rotation, and the turbine is rotatable about the longitudinal axis.

Advantageously, the wind turbine may be freely rotatable about the longitudinal axis, such that the turbine may align itself with a predominant wind direction without any external aids. The turbine may comprise one or more blades having a vertical axis of rotation parallel to the longitudinal axis of rotation. An advantage of such an orientation of rotor blades, is that the rotor is optimally placed for rotation irrespective of the predominant wind direction, and does not require re-alignment in the event of a change in wind direction.

The rotation of the turbine may rotate the outer sleeve member relative to the inner sleeve member, and the outer sleeve member and the inner sleeve member may respectively comprise rotor and stator components of an electric generator. This minimises the number of components required in the wind turbine, since the generator may effectively be comprised within the rotation means.

The wind turbine may comprise a rotatable support disposed on the mast, arranged to rotate with the outer sleeve member, and may also comprise electric power transmitting means operatively coupled to the turbine, and supported by the rotatable support. In this way as the turbine rotates about the longitudinal axis, the rotatable support supporting the power transmitting means rotates with the turbine, preventing twisting of the power transmitting means, and also ensures that a permanent power and signal transmission connection is maintained irrespective of the position of the turbine.

It will be appreciated that features of different aspects of the invention may be combined where context allows. Furthermore, features of the aspects of the invention may constitute further independent inventive aspects. Furthermore, methods of providing the functionality of any one or combination of the features of the different aspects of the invention may be provided.

Description of the Figures

Figure 1 is a cross-sectional view of a rotation unit disposed on the support mast of a wind turbine;

Figure 2 is a cross-sectional view of a horizontal axis wind turbine, comprising a rotation unit; Figure 3 is a plan view of the rotation unit disposed on the support mast of Figure 1, taken along the line AA;

Figure 4 is a cross-sectional view of a rotatable mast cover arranged to support a shielded cable;

Figure 4a is a three-dimensional perspective view of the mast cover illustrated in Figure 4;

Figure 4b is a plan view of a rotatable support structure enabling rotation of the mast cover of Figures 4 and 4a;

Figure 5 is a cross-sectional view of a rotation locking mechanism;

Figure 6 is a cross-sectional view of a vertical braking safety device disposed in the inner sleeve member;

Figure 6a is an enlarged view of the braking safety device of Figure 6;

Figure 7 is a cross-sectional view of a vertical axis wind turbine comprising a rotation unit, the inner and outer sleeve members of the rotation unit respectively comprising rotor and stator components of an electric generator-

Figure 8 is a schematic diagram of a control system used to control operation of the rotation unit of Figure 1 and the wind turbines of Figures 2 and/or 7. Description

Figures 1 illustrates the apparatus of the present invention used in conjunction with the support mast of a wind turbine. In particular, in Figure 1 a system 1 is provided comprising a rotation unit 2, which is mounted around a hollow support mast 3 as shown.

Figure 2 illustrates a wind turbine system 20. Specifically, Figure 2 illustrates how the embodiment illustrated in Figure 1, may be adapted to function as a wind turbine 20, by fitting a rotor-generator unit 16 to the rotation unit 2. All shared features common to both Figures 1 and 2 are labelled with the same reference numerals.

Turning to Figure 1, the rotation unit 2 comprises two annular sleeve members 4, 5 arranged concentrically. The freedom of motion of the inner sleeve member 4 is constrained such that it can move up and down the support mast 3, but cannot rotate about the mast 3. The inner surface 6 of the inner sleeve member 4 is designed to be of complementary shape to the support mast 3. The outer sleeve member 5 is arranged to be freely rotatable about the inner sleeve member 4.

Figure 2 illustrates a rotor-generator unit 16 attached to the rotation unit 2, wherein the rotation unit 2 is arranged such that wind pressure on the attached rotor-generator unit 16, or on the optional wind vane 17, may be capable of rotating the rotor-generator unit 16 into alignment with a prevailing wind direction B. In preferred embodiments, the rotor-generator unit 16 may be comprised of a wind turbine 18 connected to a generator unit 19, such that rotational motion of the turbine 18 causes an electric current to be generated in the generator unit 19. In such

embodiments, the skilled addressee will appreciate that whilst the wind vane 17 may be optional, its presence may facilitate the rotation of the rotor-generator unit 16 to align it with the prevailing wind direction B.

In certain embodiments, the wind vane 17 may be attached to the freely rotatable outer sleeve member 5, in a position substantially opposite to the position of the rotor-generator unit 16. Wind pressure on the wind vane 17 may cause a torque about the axis of rotation C of the rotation unit 2, which may cause the outer sleeve member 5, comprising the rotor-generator unit 16 attached to its surface, to rotate about the axis C until the wind vane 17 is in a substantially down-wind position (i.e. the wind vane 17 is downwind of the rotor-generator unit 16), aligning the horizontal axis of rotation D of the rotor-generator unit 16 with the dominant wind direction B. This ensures the optimal angle of incidence between the incident wind direction B and the rotor blades 18 may be achieved.

Returning to Figure 1. The rotation unit 2, comprising the two annular sleeve members 4, 5 may be manufactured from steel, aluminium, composite materials, or a combination of any of the aforementioned, as required. The outer sleeve member 5, to which the rotor-generator unit 16 (illustrated in Figure 2) may be attached, may be connected to the inner sleeve member 4 in a way that allows free rotation of the outer sleeve member 5 with minimal frictional effects. This may be achieved by using either ball bearings, tapered roller bearings, or rollers or gliders 7, placed between the inner and outer sleeve members 4, 5 to minimise frictional effects. The rotational motion of the inner sleeve member 4 about the support mast 3 is restricted, i.e. it is not free to rotate around the support mast 3. The inner sleeve member 4 is fitted around the support mast 3, resting on one or more small wheels 8, forming a clearance 9 between the inner surface 6 of the inner sleeve member 4, and the exterior surface of the support mast 3. The one or more small wheels 8 may be adjustable in pressure, for example with an adjustment screw mechanism (not shown), in order to adjust the concentric position of the inner sleeve member 4 such that its surface is equidistant to the surface of the support mast 3 around the full circumference, and to adjust the amount of friction created between the small wheels 8 and the surface of the support mast 3. The one or more wheels 8 are arranged to rotate in a direction parallel to the axis of rotation C, thereby enabling vertical lowering and lifting of the rotation unit 2, whilst the friction between the wheels 8 and the surface of the support mast 3 restricts the motion of the inner sleeve member 4, such that it is not free to rotate around the support mast 3.

Alternatively, the functionality provided by the one or more small wheels 8 may be supported by or replaced with one or more guide rails (not shown) running vertically along the length of the support mast 3. Furthermore, one or more sliders may be fitted to the inner sleeve member 4, the sliders being coupled with the one or more guide rails, thereby preventing the inner sleeve member 4 from rotating about the support mast 3. The one or more guide rails and coupled sliders, enable vertical lowering and lifting of the rotation unit 2, along the length of the support mast 3. Equally, and turning to Figure 2, the alignment of the horizontal axis of rotation D of the rotor- generator unit 16 with the dominant wind direction B, may be supported by an active yaw system. For example, such an active yaw system could be implemented by replacing one or more rollers or gliders 7, illustrated in Figures 1 and 2, with one or more small wheels, or similar components, that are driven by electrical motors - such as stepper motors - controlled by an electronic control system (not shown) of the wind turbine 20. In such embodiments, the materials of the one or more small wheels, or similar components are selected to provide a high frictional effect, such as could be provided by rubberised wheels. In contrast with previously described embodiments, alternatively, instead of allowing free rotation with minimal frictional effects, the one or more small wheels, or similar components effectively prevent the outer sleeve member 5 from rotating around the inner sleeve member 4, due to the high frictional effect between the one or more small wheels, or similar components and the sleeve members 4, 5. In other words, rotation of the outer sleeve member 5 about the rotation axis C is prevented by the frictional resistance of the one or more small wheels, or similar components, to relative motion between the sleeve members 4, 5. Accordingly, rotating the outer sleeve member 5 relative to the inner sleeve member 4 may only be possible by activating the electrical motors controlling the operation of the one or more small wheel, or similar components. For example, to align the horizontal axis of rotation of a rotor-generator unit 16 attached to the rotation unit 2, with the dominant wind direction, requires activating the electric motors via the electronic control system of the wind turbine system 20.

The system 1 of Figure 1, further comprises a winch-based lifting mechanism, arranged to lift and/or lower the rotation unit 2 along the length of the support mast 3. The winch-based lifting mechanism may comprise an electric winch 10 mounted within the hollow body of the support mast 3, and preferably at its base. The winch-based lifting mechanism further comprises tethering means, such as one or more wire ropes or belts 11, attached at one end to a base element 12. In turn the base element 12 is attached to the winch 10 via a winch cable 10a. Alternatively, the one or more ropes or belts 11 may be directly attached to the winch 10. Similarly, in certain embodiments the base element 12 may be a pulley.

In Figure 1, the wire ropes or belts 11 run within the inside of the hollow support mast 3, from the base element 12, to which the winch 10 is attached by the winch cable 10a, to the top of the support mast 3. The wire ropes or belts 11 are directed to the exterior of the support mast 3, via one or more pulley wheels 13 mounted at the top edge of the support mast 3. One end of the wire ropes or belts 11 may be connected to the inner sleeve member 4, whilst the other end may be attached to the base element 12. In certain embodiments, the connection means for connecting the wire ropes or belts 11 with the base element 12, may comprise an optional adjustment mechanism to facilitate length and tension adjustments of the one or more ropes or belts 11. The skilled addressee will appreciate that in those embodiments where the base element 12 is a pulley, only one rope and/or belt 11 may be required. In such an embodiment it is envisaged that the rope and/or belt 11 is passed through the pulley base element 12, and each end of the rope and/or belt 11 is attached to the inner sleeve member 4. The described winch-based lifting mechanism enables the rotation unit 2 to be lowered and raised vertically along the length of the support mast 3. A mast cover 14 sits on top of the support mast 3 to protect the interior of the support mast 3. The shape of the mast cover 14 is immaterial to the present invention however, in preferred embodiments the shape may be conical, dome or cone shaped.

It will be clear to the skilled addressee that whilst the above described winch-based lifting mechanism comprises a wire rope and/or belt 3, alternative materials may be used to provide the same functionality as provided for by the wire ropes and/or belts 3, and such alternative embodiments fall within the scope of the present invention. For example, guide rails or electric rotor motors may be used in place of the wire ropes and/or belts 3. Further details regarding such alternatives, are provided in the ensuing description.

Figure 3 is a cross-sectional view from above of the system 1, taken along the line AA of Figure 1, which illustrates the rotation unit 2 of Figures 1 and 2, fitted to the exterior surface of the support mast 3. Figure 3 illustrates the concentric arrangement of inner and outer sleeve member 4, 5 of the rotation unit 2; the clearance 9, formed between the inner surface 6 of the inner sleeve member 4 and the exterior surface of the support mast 3; one or more small wheels 8; and the pulley wheels 13 arranged to direct the one or more wire ropes and/or belts 11 (illustrated in Figures 1 and 2) to the exterior of the support mast 3.

Figure 4 illustrates an arrangement of a shielded cable 21, arranged to respectively transmit power and signal transmissions from and to a generator 19 (shown in Figure 2) mounted on the rotation unit 2, and specifically to the outer sleeve member 5, in accordance with an embodiment of the present invention. The shielded cable 21 is arranged to rotate freely with the outer sleeve member 5. The shielded cable 21 is guided through the mast cover 14, which may be installed on top of the support mast 3 using a rotatable support structure 22 so that it can follow the rotation of the shielded cable 21. Figure 4a illustrates a 3-dimensional representation of the mast cover 14 illustrated in Figure 3, attached to the support mast 3. For clarity, and specifically to illustrate how the mast cover 14 may be rotatably fixed to the top of the support mast 3, the shielded cable 21 has been omitted from Figure 4a. Figure 4b is a top view of the rotatable support structure 22 fixed to the top of the support mast 3, and illustrates how the mast cover tube segment 14a may be fitted to the rotatable support structure 22.

The support structure 22 may be affixed to the top edge of the support mast 3 by two or more struts 22a . Preferably, the support structure 22, may be a ball bearing structure, wherein the outer race is connected and held in place by the two or more struts 22a, whilst the inner race is fixed to the mast cover tube segment 14a, thereby enabling rotation of the tube segment 14a relative to the outer race of the rotatable support structure 22. Alternatively, one or more ball bearings may be fitted between the walls of the mast cover tube segment 14a and the support structure 22, to enable rotation of the mast cover tube segment 14a relative to the support structure 22. It is to be appreciated that the mast cover tube segment 14a and the rotation unit 2 share the same rotation axis C.

The struts 22a are arranged in a position where they do not interfere with the pulley wheels 13, or the wire ropes and/or belts 11. The mast cover 14 may be attached to the upper end of the tube segment 14a, and the shielded cable 21 may be arranged to run through the tube segment 14a, and exiting through a side opening 14b in the tube segment 14a positioned above the support structure 22. It is to be appreciated that whilst a hollow tube segment 14a is illustrated in Figures 4 and 4a, mechanically differently shaped elements may be used in alternative embodiments of the invention, and such alternatives fall within the scope of the present invention. The shielded cable 21 runs through the internal length of the support mast 3 and may be connected to the rotating part of a slip ring assembly 23, which is mounted on the base element 12. The skilled addressee will appreciate that a slip ring is effectively a rotary coupling used to transfer electric power from a stationary unit to a rotating unit. Many different designs of slip ring are known which may be used in the present embodiment. Since such designs are common knowledge to the skilled addressee, no further discussion of the topology of the slip ring 23 ensues. For further information regarding slip rings, the interested reader is referred to any university level textbook regarding electrical devices.

The base element 12 is attached to the winch cable 10a, which itself is then attached to the electrical winch 10 illustrated in Figures 1 and 2. The wire ropes or belts 11 are connected at one end to the inner sleeve member 4 of the rotation unit 2, and at the other end to the base element 12, which is itself attached to the winch (not shown) via the winch cable 10a. An output cable 24 is attached to the stationary, non-rotating member of the slip ring assembly 23, such that electrical power input into the slip ring assembly 23 from the shielded cable 21, may be extracted and fed into an electrical power grid (not shown), or any other energy demanding means, via the output cable 24. Preferably, the output cable 24 is sufficiently long to extend by an amount, at least equal to the distance that the base element 12 travels upwards along the interior of the support mast 3, when the rotation unit 2 is lowered by spooling the winch cable 10a. The shielded cable 21 may be of fixed length, and travels in parallel with the wire ropes or belts 11.

An advantage of this embodiment is that when the rotor-generator unit 16 (illustrated in its entirety in Figure 2; Figure 4 illustrating only the generator 19) attached to the rotation unit 2 is in the operational position, and the outer sleeve member 5 rotates, due for example to a change in wind direction, the shielded cable 21 is able to rotate freely inside the support mast 3. The rotation of the shielded cable 21 follows the rotation of the outer sleeve member 5, about axis C, whilst maintaining a secure electrical connection for power and signal transmission with the slip ring assembly 23. Furthermore, in accordance with this embodiment, power and signal transmission is also available when for example the rotation unit 2, with the rotor-generator unit 16 (note that only the generator 19 is illustrated in Figure 4) attached to the outer sleeve member 5, is lowered to the ground. This may be important to control safety features such as an electronic braking system (discussed below), and to allow inspections and functional tests, which may comprise testing power and signal transmission functionality.

The electric winch 10 illustrated in Figures 1, 2 and 4 may be controlled electronically via a control system (not shown). The control system may be operatively linked to, or integrated into the electronic control system (not shown) of the rotor-generator unit 16. Such an arrangement provides for activation of the winch 10 for lowering or raising the rotation unit 2, including the attached rotor- generator unit 16, either manually or automatically. The electronic control system (not shown) may ensure that the rotor 18 (illustrated in Figure 2) is stopped and brakes are activated before the winch 10 lowers the rotation unit 2 from its operational position at the top of the support mast 3. The electronic control system may also comprise means for measuring the operational status of the rotor 18 and generator 19. On the basis of the determined operational status, the electronic control system may be configured to automatically halt the rotation of the rotor 18 and lower the rotational unit 2, when the operational status is determined to be potentially hazardous - i.e. for example in case of extreme wind speeds, where continued operation of the rotor may lead to damage.

The system may further comprise a rotor-braking mechanism (not shown) operatively coupled to the rotor-generator unit 16. The rotor-braking mechanism (not shown) may be used to stop the rotor 18 in a position that is best suited for lowering it. For example, the rotor-braking mechanism (not shown) may ensure that the rotor 18 is lowered in a position where none of the rotor blades points directly downward. The rotor-braking mechanism may be coupled with the electronic control system (not shown), and configured such that when the electronic control system is activated to lower the rotation unit 2, comprising the rotor-generator unit 16, the rotor-braking mechanism (not shown) is automatically activated to rotate the rotor 18 into a position where non of the rotor blades points downward. For example, in such an embodiment, a three-bladed rotor 18 with a 6 meter diameter may be lowered to a height of approximately 1.5 meters, or a five-bladed rotor 18 with a 2.5 meter diameter may be lowered to approximately 1 meter height, before the tips of the rotor blades come into contact with the ground. Additionally, the electronic control system, which may be operatively coupled to the rotor-braking mechanism (not shown), may be configured to allow rotation of both the rotation unit 2 about the support mast 3, and rotation of the rotor 18, only when the rotor-generator unit 16 is in an operational position. In such embodiments, the rotor- generator unit 16 may comprise a rotational position sensor (not shown) operatively connected to the electronic control system (not shown). The rotational position sensor provides a signal to the electronic control system confirming the exact rotational orientation of the rotor 18. This signal may then be used by the electronic control system to determine the orientation of the blades of the rotor 18, and to halt the rotor 18 in a position that is ideal for lowering the rotor-generator unit 16 and rotation unit 2 to the ground. It is to be appreciated that the electronic control system may not only determine the rotational orientation of the rotor 18, but may also determine the exact position of the rotor-generator unit 16 about the support mast 3. In this way, if necessary, both the rotational orientation of the rotor 18 about its axis of rotation D, and the rotational orientation of the rotor- generator unit 16 about the support mast 3, may be selectively varied to preferred positions for lowering to the ground. For example, the preferred positions may relate to predetermined positions configured in the electronic control system. Alternatively, the preferred positions may be selected by the user on an ad-hoc basis prior to lowering the rotor-generator unit 16 and the rotation unit 2.

Wind monitoring instrumentation (not shown), such as an anemometer, may be affixed to the top of the support mast 3, and preferably to the mast cover 14. The wind speed monitoring

instrumentation may measure both wind speed and direction, and may be operatively coupled to the electronic control system (not shown). When extreme wind speeds exceeding a predetermined upper threshold value are measured, the electronic control system may automatically engage the rotor-braking mechanism to halt rotation of the wind turbine 18. Furthermore, the electronic control system may also lower the rotation unit 2 to protect the rotor-generator unit 16 from being damaged. Similarly, once satisfactory wind conditions are measured (i.e. wind conditions below an upper threshold value), operation of the rotor-generator unit 16 may be initiated automatically by raising the rotation unit 2 to operational height and disengaging the rotor-braking mechanism.

Preferred embodiments of the present invention may comprise a braking system. Preferably, the braking system may comprise at least two different components - namely, a first component such as the above described rotor-braking mechanism (not shown), capable of preventing rotation of the rotor 18; and a second component, which may effectively be a rotation unit sleeve member braking mechanism (not shown) arranged to prevent rotation of the outer sleeve member 5 around the inner sleeve member 4 of the rotation unit 2. The rotation unit braking mechanism may be configured to rotate the outer sleeve member 5, such that the horizontal axis of rotation D of the rotor generator unit 16 is aligned with the dominant wind direction. As with previously described embodiments, the rotation unit braking mechanism may be operatively coupled to the electronic control system, such that its operation is controlled by the electronic control system. Furthermore, it is envisaged that the electronic control system may activate the rotation unit braking mechanism on the basis of received wind condition data measured by the wind monitoring instrumentation, if present. Equally, the electronic control system may be configured to disengage the braking system and allow operation of the rotor 18, only when the position of the rotor-generator unit 16 attached to the rotation unit 2 is above a minimum threshold height. This minimum threshold height acts as a safety measure, below which the rotor-generator unit 16 will not function.

In addition to the aforementioned braking mechanism, the present invention may also comprise a rotation unit locking mechanism. One example of such a rotation locking mechanism is illustrated in Figure 5. The locking mechanism may comprise one or more mechanical locking elements 25 arranged to secure the rotation unit 2, and specifically the inner sleeve member 4, when the rotor- generator unit 16 is in the operating position. The locking elements 25 are preferably built into the support mast 3, typically near to the top of the support mast 3. The objective of the rotation unit locking mechanism is to release the weight of the rotation unit 2 (illustrated in Figures 1 and 2) and attached rotor-generator unit 16 from the wire ropes or belts 11 supporting the weight of the rotation unit 2 and attached rotor-generator unit 16, when in an operational position. The rotation unit locking mechanism may be engaged once the rotation unit 2 and attached rotor-generator 16 is in operational position, at or near the top of the support mast 3. Figure 5 illustrates a preferred implementation of the rotation unit locking mechanism. A mechanical locking element 25, shown in the form of a triangular wedge, is held in place by a mechanical spring 26, in a position preventing the one or more wheels 8, from moving the rotation unit 2 downwards. For clarity, Figure 5 only illustrates the inner sleeve member 4 of the rotation unit 2. A wire rope or similar 27 is connected at one end to the locking element 25, and at the other end to an actuator device 28, which may be installed at the bottom of the interior of the hollow support mast 3. The actuator device 28 could, for example, be an electro-magnetic actuator, or alternatively a geared motor or a small winch. The actuator device 28 may be controlled by the aforementioned electronic control system. When activated via the electronic control system, the actuator device 28 may haul in the wire rope 27, which in turn pulls the locking element 25 into a disengaged position, wherein the one or more wheels 8 are free to move vertically along the length of the support mast 3. In the disengaged position, the rotation unit, and specifically the inner sleeve member 4 may be lowered.

Alternatively, the one or more locking elements 25, could comprise bolts, or could comprise alternatively shaped locking elements held in the engaged position by appropriately shaped mechanical springs. For the purposes of the present invention, the exact shape of the locking elements is irrelevant provided that it is able to provide an engaged position and a disengaged position as described. Furthermore, the exact means by which the required functionality is achieved is also irrelevant for present purposes, and alternative locking elements are envisaged and fall within the scope of the present invention.

Similarly, the present invention may comprise one or more vertical braking safety devices 41. One such example is illustrated in Figure 6. In the illustrated example, each vertical braking safety device 41 may comprise one or more bolts or sliding rails 29 that may be integrated into the inner sleeve member 4. The one or more bolts or sliding rails 29 may be attached at one end to one or more brake pads 33. Figure 6a illustrates an enlarged view of one vertical braking safety device 41. The upper bolt or sliding rail 29a may comprise a recess 36. Both sliding rails or bolts 29 may comprise a flange 34. One or more compression springs 30 may be arranged between the flange 34 and the interior wall 35 of the inner sleeve member 4. In the illustrated example of Figures 6 and 6a, the compression springs 30 are arranged around the circumference of the bolts or sliding rails 29, and are held in place by flanges 34 and the interior wall 35. One or more locking pins 31 maintain the vertical braking safety devices 41 in a disengaged position. In the disengaged position, one end of the locking pins 31 rests in the recess 36. When the one or more locking pins 31 are removed from the recess 36, the compression springs 30 extend, thereby exerting a force on the flange, pushing the bolts or sliding rails 29 and the one or more brake pads 33 against the outer surface of the support mast 3. The brake pads 33 are preferably comprised of a high friction material, causing a high frictional effect when pressed against the surface of the support mast 3, capable of preventing the rotation unit 2 and specifically the inner sleeve member 4 from sliding down the support mast 3, or - depending on the strength of the springs 30 - may slow down the downward movement of the rotation unit 2 to a safe velocity. Each locking pin 31 may be connected at its upper end to one of the wire ropes 11, that support the weight of the rotational unit 2 when adjusting its height position.

Each upper bolt or sliding rail 29a may be configured with a hollow cavity 42 running through it, arranged such that the wire rope 11 may be attached to the locking pins 31. Each locking pin 31 is also attached at its lower end to a tension spring 32, which is dimensioned to have a pulling force that is lower than the proportion of the rotational unit's weight supported by each wire rope 11 and locking pin 31. In this way, when the weight of the rotational unit 2 is being supported by the wire rope 11, for example when the positional height of the rotation unit 2 is being varied, the one or more locking pins 31 are pulled into the recess 36, and the one or more tension springs 32 are stretched. The vertical braking safety devices 41 may be activated in the event of a rupture of any one of the wire ropes 11 during operation. The absence of a pulling force on the one or more pins 31 resulting from the one or more wire ropes 11, causes the one or more tension springs 32 to contract, pulling the one or more locking pins 31 out of the recesses 36, which in turn releases the one or more compression springs 30, such that a force is applied to the corresponding bolts or sliding rails 29, and in the process causes the one or more brake pads 33 to be pressed against the support mast surface 3.

Figure 7 illustrates how the apparatus of the present invention may be used with a vertical axis wind turbine 37. A vertical axis wind turbine 37 is characterised by the vertical axis of rotation C of the rotor 38. The afore-described rotation unit 2 may equally be used in vertical axis type wind turbines. The skilled addressee will appreciate that in such embodiments, the rotor 38 and the rotation unit 2 share the same axis of rotation C. Accordingly, in such embodiments, the inner sleeve 4 member and outer sleeve member 5 of the rotation unit 2 may be arranged to provide the functionality of the rotor and stator component of an electric generator. For example, this might comprise including permanent magnets (not shown) on the outer sleeve member 5, which acts as an electric generator rotor, and providing one or more coils (not shown) on the inner sleeve member 4, such that relative movement between the sleeve members induces a voltage across the one or more windings in the stator (i.e. in the inner sleeve member 4). Equally, the permanent magnets may be fitted to the inner sleeve member 4, and the outer sleeve member 5 may be fitted with the one or more windings.

The rotor blades 39 of the rotor 38 are arranged concentrically around the rotation unit 2, and are connected to the outer sleeve member 5 via spokes 40. The rotor blades 39 rotate around the support mast 3, and drive the outer sleeve member 5. In such vertical wind turbine 37

embodiments, a wind vane or alternative active yaw system is not required to align the rotor- generator with a predominant wind direction.

Figure 8 is a functional diagram of an electronic control system 50 which may be used in accordance with the above described embodiments. Figure 8 illustrates the flow of control signals in the electronic control system 50. The electronic control system 50 is operatively coupled to any one of the above described wind turbines, and is arranged to control the operation of the wind turbine. The electronic control system 50 may comprise an electronic control unit 51, a sensing unit 52, a safety and maintenance unit 54, a power unit 56, a control and communication unit 58, and a rotation unit motion control unit 59. The rotor generator unit 16 may be operatively coupled to the electronic control unit 51 via a shielded cable 21, such as illustrated in Figure 4. Electrical power generated by operation of the rotor-generator unit 16 may be transmitted to the power unit 56. The power unit 56 may comprise any one or more of: a battery charger 60, arranged to store generated electrical power; a grid tie inverter 62, arranged to convert input direct current (DC) into alternating current (AC), which may be input into a power grid; one or more dump load/regulation resistors 64, arranged to maintain a substantially constant output power signal.

The sensing unit 52 may comprise a longitudinal position sensor 66 mounted on the rotor-generator unit 16, or the rotation unit 2, arranged to measure the longitudinal position of respectively the rotor-generator unit 16 and the rotation unit 2, relative to the support mast 3. The sensing unit 52 may also comprise a turbine rotational speed/position sensor 68, arranged to measure the speed of rotation of the turbine, in addition to providing positional information regarding the turbine blades. For example, the turbine blades' positional information may be used to ensure that the turbine blades are not damaged when lowering the rotor-generator unit 2, as mentioned previously - i.e. by ensuring that the turbine blades are not pointing directly downwards during lowering. A wind speed sensor 70 may also be comprised within the sensing unit 52, arranged to measure wind speed, and direction. On the basis of the sensor 66, 68, 70 readings, the motion of the rotation unit 2 may be controlled using the rotation unit motion control unit 59.

The rotation unit motion control unit 59 may comprise an outer sleeve rotation motor 72, arranged to electronically control rotation of the outer sleeve member 5 relative to the inner sleeve member 4. For example, the one or more wheels 7 may be electronically activated via the outer sleeve rotation motor 72. The longitudinal position of the rotation unit 2 may be controlled by the longitudinal motor 74, arranged to electronically activate the guide means used to selectively vary the longitudinal position of the rotation unit 2 relative to the support mast 3. The longitudinal motor 74 is optional, and in embodiments where the longitudinal position of the rotation unit 2 is selectively varied using the winch 10, may be dispensed with. The rotation unit motion control unit 59 may be used to selectively vary the position of the rotor-generator unit 2, on the basis of positional readings generated by the sensing unit 52. The safety and maintenance unit 54 may comprise a mechanical brake actuator 76 operatively coupled to the previously described rotor-braking mechanism (not shown) operatively coupled to the rotor-generator unit 16. The safety and maintenance unit 54 may also comprise a winch control unit 78 arranged to electronically control the activation of the winch 10. For example, to

electronically control the lifting and lowering of the rotor-generator unit 2. Similarly, the safety and maintenance unit 54 may also comprise the locking mechanism actuator 28, arranged to activate the one or more locking elements 25, illustrated in Figure 5. For example, the actuator 28 may be configured to engage the one or more locking mechanisms 25 when the longitudinal position of the rotor-generator unit 2, as determined from positional data received from the longitudinal position sensor 66, is at a predetermined height.

The electronic control unit 51 may be arranged to receive and process all the data received from the different units (and sensors), and is operatively coupled to the control and communication unit 58. The control and communication unit 58 may comprise a control interface 82, arranged to receive data inputs from the electronic control unit, the input data relating to any data generated by any one of the units 52, 54, or 59. The control interface 80 may be operatively coupled to a user terminal 84 via a network interface 82. The user terminal 84 provides a means for enabling a user (not shown) to manually control the operation of the wind turbine, in addition to displaying the state of the wind turbine on the basis of received data. The user terminal may be located local to the electronic control system 50, or alternatively, it may be located remotely. For example, the user terminal may be operatively coupled to the control and communication unit via a shared communication network (not shown) such as the internet. Similarly, the network interface 82 may be arranged to enable communication with a mobile telephone (not shown). In this way a user may manually control the operation of the wind turbine remotely using a mobile telephone. This feature may be particularly advantageous in domestic applications. For example, it is envisaged that a user may be able to control operation of the wind turbine using any networked processing means such as a personal computer, personal digital assistant (PDA), or mobile telephone via a local access network (LAN).

The electronic control unit, or the control and communication unit 58 may be configured with a control software program pre-programmed to execute a variety of functions, such as stopping and lowering or raising and starting the rotor-generator unit 16, according to a number of

predetermined inputs. Such inputs can include, but are not limited to, user control inputs via the user control interface 80, environmental condition signals - such as wind speed - and operational status feedback generated from any one of the sensing units 66, 68, 70, control inputs provided via the network interface 82, or a combination thereof. The software program may be configured to ensure safe operation of the rotor-generator unit 2, by analysing the generated signals. For example, the control software program may be configured to ensure safe operation of the rotor-generator unit 16 depending on the environmental conditions (i.e. wind speed, and direction) and the operational status of the rotor-generator unit 16, or of the rotation unit 2.

As a safety feature, the electronic control unit 51 may be arranged to override any user input control signals, such as for example in the event of high wind speeds, to prevent the rotor-generator unit 16 and the rotation unit 2 from being damaged. The electronic control unit 51 may be arranged to automatically lower the rotation unit 2 and attached rotor-generator unit 16 when very high winds are measured which might damage the rotor 18. Similarly, the rotation unit 2 and attached rotor- generator unit 16 may be automatically raised to operational height, when the wind conditions are determined as being safe for operation of the rotor 18.

The network interface 82 may be operatively connected to a server or multiple servers, running a control system software program configured to monitor any number of the above described wind turbines.

Wind turbines comprising the present invention benefit from several different advantages, amongst which:

For the purposes of installation, various parts of the wind turbine, in particular the rotor- generator unit and the optional wind vane, can be mounted by an installer from a ground level position after the mast has been erected to the upright position.

For the purposes of maintenance, the wind turbine rotor and generator assembly can easily be lowered close to ground level, without the need to lower the mast. This allows for maintenance, inspection, repair or cleaning activities to be carried out by a single operator in a shortened period of time. It also eliminates the need for having a cleared ground area onto which the mast and wind turbine assembly would have to be lowered. The automatic lowering of the rotational unit acts as an additional safety feature in the rare occasion of extreme and potentially catastrophic wind speeds. When a wind speed exceeding the rated maximum upper threshold wind speed and hence potentially damaging the structure is either detected or forecast, the rotor-generator unit can be stopped and lowered into a safe ground position, thus reducing the load on the structure. This feature also provides potential material and cost savings in the construction of the wind turbine rotor and mast, as the wind turbine may not need to be overbuilt to withstand excessively high loads resulting from extreme wind conditions, which rarely occur. For example, common small wind turbines are built to survive winds speed of >140mph. This greatly increases manufacturing costs and complexity, despite such wind speeds occurring very occasionally.

In contrast to the prior art wind turbines, a wind turbine construction having vertically movable rotor-generator unit, which may be lowered to the ground without requiring the support mast to be lowered, as described herein, reduces the stress on foundations and masts. The prior art wind turbines comprise hinged masts, and when lowered for maintenance, the hinged masts experience significant stresses due to the position of the heavy rotor-generator unit being positioned at the top of the mast.

The skilled addressee will appreciate that any size of turbine may be used with the present invention, and such embodiments fall within the scope of the present invention. Furthermore, it is to be appreciated that the herein described embodiments are for illustrative purposes only, and are not limiting to the present invention.

Claims

1. An apparatus for mounting a wind turbine on a support mast, the apparatus comprising: an inner sleeve member arranged to be disposed around the support mast;

an outer sleeve member arranged to support the wind turbine, the outer sleeve member being concentrically mounted around the inner sleeve member; and wherein

the outer sleeve member is arranged to be rotatable relative to the inner sleeve member.

2. The apparatus of claim 1, wherein the inner sleeve member and the outer sleeve member define a longitudinal axis of rotation parallel to the length of the support mast, and the outer sleeve member is arranged to be rotatable about the longitudinal axis.

3. The apparatus of any previous claim, further comprising:

a rotation means arranged to enable rotation of the outer sleeve member relative to the inner sleeve member.

4. The apparatus of claim 3, wherein the rotation means comprises one or more wheels disposed between the inner sleeve member and the outer sleeve member, the wheels being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the longitudinal axis.

5. The apparatus of claim 3, wherein the rotation means comprises one or more bearings disposed between the inner sleeve member and the outer sleeve member, the bearings being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the longitudinal axis.

6. The apparatus of claim 3, wherein the rotation means comprises one or more sliders disposed between the inner sleeve member and the outer sleeve member, the one or more sliders being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the longitudinal axis.

7. The apparatus of any one of claims 3 to 6, further comprising: an electronic control system operatively coupled to the rotation means, arranged to activate the rotation means for rotating the outer sleeve member relative to the inner sleeve member.

8. The apparatus of claim 2, or claim 3 as dependent on claim 2, and any one of claims 4 to 7, further comprising:

guide means arranged to constrain motion of the inner sleeve member in a longitudinal direction relative to the outer sleeve member.

9. The apparatus of claim 8, wherein the guide means comprises:

one or more wheels fitted to the inner sleeve member between the sleeve member and the support mast, arranged to rotate in the longitudinal direction.

10. The apparatus of claim 8, wherein the guide means comprises:

one or more sliders fitted to the inner sleeve member, arranged to enable movement in the longitudinal direction when coupled to one or more guide rails disposed on the support mast.

11. The apparatus of any previous claim, wherein the outer sleeve member is freely rotatable relative to the inner sleeve member.

12. The apparatus of any previous claim, further comprising:

longitudinal position varying means coupled to the inner sleeve member, arranged to vary the longitudinal position of the inner sleeve member relative to the support mast.

13. The apparatus of claim 12, wherein the longitudinal position varying means comprises: a winch coupled to the inner sleeve member via a tether, the winch being arranged to vary the longitudinal position of the inner sleeve member relative to the support mast, by varying the tether length.

14. The apparatus of claim 13, wherein the winch is disposed within the support mast.

15. The apparatus of any one of claims 13 to 14, wherein the winch is electronically activated.

16. The apparatus of any one of claims 13 to 14, wherein the winch is manually activated.

17. The apparatus of any one of claims 13 to 15, wherein the winch is operatively coupled to a control system, and operation of the winch is activated by the control system to vary the longitudinal position of the inner sleeve member relative to the support mast.

18. The apparatus of claim 17, wherein the control system is arranged to activate the winch to lower the inner sleeve member's longitudinal position relative to the support mast, when wind conditions exceed a predetermined threshold value.

19. The apparatus of claim 8, or of any one of claims 9 to 18 when dependent on claim 8, further comprising:

locking means arranged to maintain the inner sleeve member in a fixed longitudinal position relative to the support mast.

20. The apparatus of claim 13, or any one of claims 14 to 19 when dependent on claim 13, further comprising:

braking means operatively coupled to the tether, arranged to have a first position when the tether is in tension, and a second position when the tether is not in tension; and wherein the braking means is arranged to constrain the longitudinal motion of the inner sleeve member relative to the support mast, when in the second position.

21. The apparatus of any previous claim, further comprising:

a wind turbine fitted to the outer sleeve member.

22. The apparatus of any previous claim, further comprising:

an electric generator fitted to the outer sleeve member.

23. A wind turbine comprising:

a support mast;

a turbine;

rotation means comprising:

an inner sleeve member disposed around the support mast; an outer sleeve member concentrically mounted around the inner sleeve member, the outer sleeve member being arranged to be rotatable relative to the inner sleeve member, and having a longitudinal axis of rotation; and wherein

the turbine is disposed on the outer sleeve member.

24. The wind turbine of claim 23, wherein the rotation means further comprises:

one or more wheels disposed between the inner sleeve member and the outer sleeve member, the wheels being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the axis of rotation.

25. The wind turbine of claim 23, wherein the rotation means further comprises:

one or more bearings disposed between the inner sleeve member and the outer sleeve member, the bearings being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the axis of rotation.

26. The wind turbine of claim 23, wherein the rotation means comprises one or more sliders disposed between the inner sleeve member and the outer sleeve member, the one or more sliders being arranged to enable rotation of the outer sleeve member relative to the inner sleeve member about the axis of rotation.

27. The wind turbine of any one of claims 23 to 26, further comprising an electronic control system operatively coupled to the rotation means, arranged to activate the rotation means for rotating the outer sleeve member relative to the inner sleeve member.

28. The wind turbine of any one of claims 23 to 27, further comprising:

29. The wind turbine of claim 23, wherein the guide means comprises:

one or more wheels disposed between the inner sleeve member and the support mast, arranged to rotate in the longitudinal direction.

30. The wind turbine of claim 23, wherein the guide means comprises:

one or more sliders fitted to the inner sleeve member; one or more guide rails disposed in a longitudinal orientation along the support mast; and wherein

the one or more sliders are coupled to the one or more guide rails enabling longitudinal displacement of the inner sleeve member along the support mast.

31. The wind turbine of any previous claim, further comprising:

32. The wind turbine of claim 31, the longitudinal position varying means comprises:

a winch coupled to the inner sleeve member via a tether, the winch being arranged to vary the longitudinal position of the inner sleeve member relative to the support mast, by varying the tether length.

33. The wind turbine of claim 32, wherein the winch is disposed within the support mast.

34. The wind turbine of any one of claims 32 to 33, wherein the winch is electronically activated.

35. The wind turbine of any one of claims 32 to 33, wherein the winch is manually activated.

36. The wind turbine of any one of claims 31 to 35, wherein the winch is operatively coupled to a control system, and operation of the winch is activated by the control system to vary the longitudinal position of the inner sleeve member relative to the support mast.

37. The wind turbine of claim 36, wherein the control system is arranged to activate the winch to lower the inner sleeve member's longitudinal position relative to the support mast, when wind conditions exceed a predetermined threshold value.

38. The wind turbine of any one of claims 23 to 37, further comprising:

39. The wind turbine of claim 32, or any one of claims 33 to 38 when dependent on claim 32, further comprising:

40. The wind turbine of any one of claims 23 to 39, wherein the turbine comprises one or more blades having a horizontal axis of rotation, and the turbine is rotatable about the longitudinal axis.

41. The wind turbine of any one of claims 23 to 40, wherein the turbine is freely rotatable about the longitudinal axis.

42. The wind turbine of any one of claims 23 to 39, wherein the turbine comprises one or more blades having a vertical axis of rotation parallel to the longitudinal axis of rotation.

43. The wind turbine of claim 42, wherein rotation of the turbine rotates the outer sleeve member relative to the inner sleeve member.

44. The wind turbine of any one of claims 42 or 43, wherein the outer sleeve member and the inner sleeve member respectively comprise rotor and stator components of an electric generator.

45. The wind turbine of any one of claims 23 to 41, further comprising a rotatable support disposed on the mast, arranged to rotate with the outer sleeve member.

46. The wind turbine of claim 45, further comprising:

electric power transmitting means operatively coupled to the turbine, and supported by the rotatable support.