FI ELD OF THE I NVENTION

The present invention relates to a wind turbine, and to a generator, which is suitable for use in a wind turbine but may find other application.

BACKGROUND ART

It is well known to provide wind turbines to generate electricity. Most of these have a rotor blade which rotates about an axis, and the rotation of the rotor is linked to a generator usually through a gear mechanism. The rotor blade, generator and gear mechanism are three separate components connected together, and the resultant turbine is relatively complex and expensive to construct. Mechanical linkages within conventional turbine constructions reduce mechanical efficiency and the amount of energy that can be harvested.

A problem with known generators is that the electricity generation is created by the passing of magnets over coils with a ferrous core. Usually a circular array of magnets is rotated relative to a circular of coils with a ferrous core. The magnetic flux lines from the magnets are drawn to the ferrous cores, and this adds to the torque required to get the turbine blades to rotate which is especially noticeable when each magnet passes a coil (sometimes referred to as cogging). This prevents generation of electricity in low wind velocity conditions.

The invention seeks to provide a solution to this problem, and especially to create a generator which can be operated by a wind turbine in low wind conditions.

SUMMARY OF THE I NVENTI ON

I n its first aspect, the present invention therefore provides a wind turbine comprising a rotor rotatable around a horizontal axis and supported at either end by a housing, the rotor comprising a plurality of turbine blades adapted to cause rotation of the rotor when exposed to an airflow, and at least one disc arranged transverse to the axis and which carries a plurality of magnets spaced from the axis, the housing also supporting a plurality of coils in fixed positions on the housing, facing the plurality of magnets, the rotor comprising at least 4 magnets for every 3 coils supported by the housing.

We prefer that the magnets are spaced a uniform radius from the axis, to provide for a smoother and more efficient operation.

I n some embodiments, the turbine blades are elongate in the direction of the axis. This presents a substantial surface area to the wind and allows for a configuration that can be located at convenient positions on wind-directing structures such as a roof or a solar panel.

The housing can include a prismatic shield around the turbine, having at least two axially-extending apertures to provide a fluid flow inlet and outlet. The prismatic shield can have a polygonal cross-section, or a circular cross-section (i.e. a cylindrical shape).

The rotor can include a first annular element, with the magnets arranged on an annular face thereof with magnetic poles oriented in a radial direction relative to the axis. Likewise, a second annular element can form part of the housing, on which the coils are supported, and which is co-axial with the first annular member. The second annular member is ideally radially outside the first annular member.

The coils are preferably coreless, or have a non-ferrous core. We also prefer that at least the parts of the rotor and the housing supporting the magnets and the coils are made of non-electrical conductive material. To this end, the rotor can include a circular plate on which the magnets are spaced, ideally adjacent the periphery of the circular plate. Also, the housing can includes a circular or polygonal plate on which the coils are spaced, ideally adjacent the periphery of the circular or polygonal plate. These circular plates are preferably non-conductive or at least non-ferrous.

The coils are preferably wired to create two or more phases of electricity generation, ideally three.

The spacing of magnets with respect to the coils is ideally such that when one magnet is positioned over a coil, the adjacent magnet is positioned over a space between coils. This is assisted by the 4:3 ratio mentioned above. We also prefer that the coils are elongate, with two straight side edges joined by semi-circular ends. I n this case, the width of each magnet is preferably not greater than the width of the coils between the two straight edges. We also prefer that the spacing between adjacent magnets is such that in rotation when one magnet is positioned over one longitudinal side edge of a coil, the adjacent magnet is positioned over the space between coils, and the next adjacent magnet passes over the other longitudinal side edge of the adjacent coil.

The rotating member can have a pair of opposing circular plates with turbine blades between the circular plates, and the axis passing though the centre of the plates, at least one circular plate supporting magnets, and the casing for the turbine including a pair of spaced end plates opposing the rotating member circular plates, at least one plate supporting coils.

I n its second aspect., the present invention provides a generator comprising an outer annular member having a peripheral wall, an inner annular member having a peripheral wall, said inner member being adapted to rotate relative to the outer member with the outer member peripheral wall adjacent the inner member peripheral wall, said inner annular member being adapted to rotate when fluid passes through it, an array of magnets radially spaced in or adjacent the inner member peripheral wall, and an array of coils radially spaced in or adjacent the outer member peripheral wall, in use rotation of the inner annular member relative to the outer annular member causing the magnets to induce current in the coils.

The magnet orientation of polarity of each magnet is preferably normal to the axis of the rotation. The magnets are ideally supported in cavities formed in the inner member peripheral wall. Likewise, the coils are ideally supported in cavities formed in the outer member peripheral wall.

Again, we prefer that the coils are configured to supply multi-phase alternating current electricity such as two- or three-phase power.

I nter-connectivity between the coils and phases can be provided means of circumferentially configured channels within the periphery of the outer member. The inner rotating member can be connected to a co-axially aligned array of turbine blades, preferably elongate.

Usefully, these features can permit the rotational movement of the inner annular member by fluid flow to be substantially entirely within the surface area boundary formed by the circumference of the outer annular member.

The turbine blades are ideally supported inside the inner member peripheral wall, preferably at their circumferential extremities.

The outer annular member can conveniently be formed of two halves, which assemble together either side of the inner rotating member. Each half can of course be formed of sub-components.

The inner peripheral wall can be located at one end of a cylinder of blades.

I n use, a pair of such generators can be provided one at each end of a cylinder of blades, with the inner peripheral wall of each generator being connected to opposing ends of the cylinder of blades.

I n the above-defined generator, we prefer that there are four magnets for every three coils, as with the wind turbine. Ideally, there are 18 coils and 24 magnets.

It is also convenient for the magnets to be circular. Likewise, the coils can be circular in this aspect of the invention. The coils are ideally configured to deliver multi phase alternating current electricity. The diameter of each magnet is ideally approximately equal to the internal diameter of the coils, and the internal diameter of the coils is ideally substantially one-third of the outer diameter of the coils.

I nter-connectivity between coils can be provided by means of peripheral circumferentially configured wiring channels.

We prefer, again, that the spacing between adjacent magnets of the generator is such that in rotation when one magnet is positioned over the leading perimeter of a coil, the adjacent magnet is positioned over the space between coils, and the next adjacent magnet passes over the trailing perimeter of the adjacent coil. The inner annular member can rotate on an axis supported by the outer annular member. The axis is provided by a suitable shaft, which can be supported on arms extending inwardly from an outer annular peripheral wall.

Generally speaking, in both aspects, we prefer that the magnets and/or coils are supported or embedded on a non-electrically conductive structure. Also, the blades (at least) can be formed by 3D printing, injection moulding or extrusion moulding.

BRI EF DESCRI PTI ON OF THE DRAWI NGS

Embodiments of the present invention will now be described by way of example, with reference to the accompanying figures in which;

Hgure 1 shows an exploded view of a first embodiment of a turbine according to the present invention,

Hgure 2A shows a plan view of coils on end plates of fig 1 ,

Hgure 2B shows a plan view of magnets on a rotor of fig 1 ,

Hgure 2C shows a schematic cross section view of two adjacent coils and three magnets of fig 1 ,

Hgure 3 shows an assembled view of Hgure 1 ;

Hgure 4A shows an exploded perspective view of a second embodiment,

Hgure 4B shows an assembled view of the embodiment of Hgure 4A,

Hgure 5A shows an exploded perspective view of a third embodiment, and

Hgure 5B shows an assembled view of the embodiment of Hgure 5A.

DETAI LED DESCRI PTI ON OF THE EMBODI MENTS

Referring to the drawings there is shown a turbine 1 for generating electricity.

Turbine 1 has a rotating member 10 and a casing 20. Rotating member 10 has eight (or another number, such as six) turbine blades 1 1 radially spaced in a circular array which are supported for rotation about an axis X-X between a pair of circular plates 12,13. Rates 12, 13 have outer end faces 12A, 13A. Rate 12 forms part of the‘rotor’ of the invention. As shown in Figure 2B, plate end face 12A supports an array of forty eight magnets 14. Magnets 14 may be on the surface of end face 12A, or embedded in it. I n this example, magnets 14 are equally radially spaced about the axis X and lie adjacent the periphery of circular plate 12.

A casing 20 has a pair of spaced octagonal (or other sided polygon shape, or circular) end plates 21 , 22 with the axis X-X passing through their centre. End plate 21 opposes circular plate 12, with its inner face 21 A facing the end face 12A of circular plate 12. End plate 22 opposes circular plate 13, with its inner face 22A facing the end face 13A of circular plate 13. End plate 21 forms part of the‘housing’ of the invention.

As shown in Figures 1 and 2A, end plate face 21 A supports an array of thirty six coreless generative coils 24. Coils 24 may be on the surface of end plate face 21 A or embedded in it. The coils 24 are radially spaced equally about the axis X-X, in this example, and lie adjacent the periphery of hexagonal end plate 21.

End plates 21 , 22 of casing 20 are spaced apart by six elongate spacers 25 (one such spacer being shown in figure 1 ). Spacers 25 each have slots 25A to engage with projections 21 B and 22B on the octagonal edges of end plates 21 ,22, but they may engage in an alternative manner.

The end plates may be octagonal with elongate spacers between hexagonal end plates edges. FVeferably six spacers are provided to create an octagonal elongate casing with an air inlet and an air outlet in gaps between the six spacers. I n such an arrangement, the casing will have two missing spacers, to create a wind flow "I N" gap A and a wind flow "OUT" gap B, whereby the turbine blades can be rotated by the wind. I n use rotation of the rotating member induces current in the coils.

Because the coils are coreless, there is no ferrous core for the magnetic flux lines to be drawn to. This has the effect of eliminating the‘cogging’ effect mentioned above, so that the turbine will be able to operate at low wind speeds.

Ideally the rotating member and casing are both made of non-electrically conductive (and especially non-ferrous) material which results in zero field flux draw towards the coils. It is envisaged that the blades could be made of plastic (e.g. by a 3D printing process, injection or extrusion moulding) and the remaining parts formed from sheet material such as plywood or plastics sheet material. This makes the turbine very economical to produce. Alternatively the entire rotating member (apart from the magnets) could be made from 3D printing, or injection moulding.

Although 48 magnets are shown with 36 coils, the number of coils and magnets could be different. It has been found beneficial however for there to be four magnets for every three coils. The coils are preferably elongate, with two straight side edges joined by semi-circular ends. The width of each magnet is preferably not greater than the width of the coils between the two straight edges.

Figure 2C shows a schematic cross section view of two adjacent coils 24 each with first and second straight side edges 24A, 24B, and three magnets 14A, 14B, 14C passing over the coils. It will be seen as a result of the 4:3 ratio of magnets to coils, that the circumferential spacing of magnets 14 with respect to the coils 24 is such that when one magnet is positioned over a coil, the adjacent magnet is positioned over a space between coils. Also the circumferential spacing between adjacent magnets is such that in rotation when one magnet 14C is positioned over the second longitudinal side edge 24B of a coil, the adjacent magnet 14B is positioned over the space between coils, and the next adjacent magnet 14A is just passing over the first longitudinal side edge 24A of the adjacent coil.

Preferably the coils are wired to create two or more phases of electricity generation, more preferably three phases.

Although the housing in the drawing is shown as polygonal, the housing could be circular, with an air entry and exit defined as a portion of the circumference. The notion behind this is that if the interior surface has a circumference, internal drag caused by eddying of the wind within the interior of the turbine housing will be minimized, thereby increasing turbine efficiency. Snce the components may be constructed from plastic, a circular design can easily be achieved cheaply using this manufacturing process.

The turbine of the invention has numerous other benefits as follows: i) there are no gears between a rotor and a generator to create losses ii) the magnets and coils on their respective plates result in a very thin generator, whereby when the turbine is installed a greater percentage of the available harvesting area is dedicated to collection of the wind energy iii) the magnet configuration is on a plate and runs perpendicular to the axis of rotation iv) because the coils and magnets are adjacent the periphery of their respective plates, this results in higher rotational speeds and proportional increase in torque resulting in increased velocity and more stable generative capacity v) the turbine start up torque is defined by the bearing friction only, rather than the need to overcome cogging forces vi) the turbine is very simple to construct, and can be transported as a "flat pack" to be assembled at a destination vii) the generator shares common parts with the rotating blades viii) as there is no cogging, there is less vibration making the device suitable for use in proximity to habitation.

It is envisaged that the turbine described incorporating the generator of the invention may conveniently be positioned along the top edge of a solar photovoltaic panel (e.g. in a solar farm) with the turbine benefitting from wind which is accelerated over the top of the solar panel. Alternatively the turbine may be placed along the ridge of buildings, or at the vertices of walls.

Figures 4A and 4B show a second embodiment. Generator 101 has an outer annular member 1 10 having a peripheral wall 1 1 1.

Annular member 1 10 is formed from two mirror image ring components 1 10A, 1 1 OB. Components 1 10A, 1 1 OB are joined together using austenitic bolts 1 12. Each component 1 10A, 1 1 OB has three inwardly-extending arms 1 13A, 1 13B, 1 13C and 1 14A, 1 14B, 1 14C respectively, which support the opposing ends of a shaft 1 15 which acts as a rotational axis. Each component 1 10A, 1 1 OB may be formed of sub-components joined together for ease and economies of manufacture. Member 1 10 is made of non-electrically conductive material such as plastics.

Generator 101 has an inner annular member 120 having a peripheral wall 121 and sandwiched between the ring components 1 10A, 1 1 OB. I nner member 120 has an inwardly directed array of turbine blades 122 and is supported to rotate on shaft 1 15 relative to the outer member 1 10, with the outer member peripheral wall adjacent the inner member peripheral wall. The inner annular member 120 rotates when fluid (gas or liquid) passes through blades 122. The inner rotating member is co-axially aligned with the array of turbine blades. The outer annular member two halves 1 10A, 1 10B assemble together either side of the inner rotating member to encase the inner rotating member 120. Member 120 is made of non-electrically conductive material such as plastics. Bearing support surfaces may be added in order to reduce rotational friction between inner and outer annular members.

An array of radially spaced cavities 123 are formed in the inner member peripheral wall 121 , and support an array of 24 magnets 124 radially spaced in the inner member peripheral wall. Magnets 124 are preferably rare earth magnets, and are preferably circular.

An array of radially spaced cavities 1 16 are formed in the outer member peripheral wall 1 1 1 which support an array of 18 coils 1 17 radially spaced in the inner member peripheral wall. Coils 1 17 are coreless, so that no magnetism is induced into a core which might cause cogging. Coils are configured to deliver multi-phase alternating current electricity. I nter-connectivity between coils is by means of peripheral circumferentially configured wiring channels.

Preferably the coils are circular. Preferably the diameter of each magnet is approximately equal to the internal diameter of the coils. Preferably the internal diameter of the coils is substantially one-third of the outer diameter of the coils. I n a preferred configuration, the spacing between adjacent magnets is such that in rotation when one magnet is positioned over the leading perimeter of a coil, the adjacent magnet is positioned over the space between coils, and the next adjacent magnet passes over the trailing perimeter of the adjacent coil.

The magnet orientation of polarity of each magnet is preferably normal to the axis of the rotation. It will be apparent that there are four magnets for every three coils; in this embodiment there are 18 coils and 24 magnets. I n use, rotation of the inner annular member relative to the outer annular member causing the magnets to induce current in the coils, whereby to generate electricity.

Referring now to Figures 5A and 5B, there is shown a generator 130 according to a third embodiment of the invention. Generator 130 has a cylinder of turbine blades 131 adapted to rotate on an axis X-X. Blades 131 are supported at either end by a pair of inner annular members 140A, 140B with peripheral walls 141 A, 141 B supporting circular end plates 142A, 142B. An array of radially spaced cavities 143 are formed in the inner member peripheral walls 141 A, 141 B which support an array of magnets 144 radially spaced in the inner member peripheral wall. Magnets 144 are preferably rare earth magnets and are preferably circular. Members 140A, 140B are made of non-electrically conductive material such as plastics.

A pair of outer annular member 1 10A, 1 1 OB (identical to that shown in Figure 4A) surround the inner annular members 140A, 140B, each annular member 1 10A, 1 1 OB supporting coils 1 17 in cavities 1 16. Coils 1 17 are coreless, so that no magnetism is induced into a core which might cause cogging. Members 1 10A, 1 1 OB are made of non-electrically conductive material such as plastics.

A shaft 150 passes through the arms 1 13A, 1 13B, 1 13C and 1 14A, 1 14B, 1 14C of each annular member, through the centre of end plates 142A, 142B, and through the cylinder of turbine blades 131 , whereby the blades 131 and inner annular members can rotate relative to outer annular members 1 10A, 1 10B.

Again, there are four magnets for every three coils. I n this embodiment there are 18 coils and 24 magnets. FVeferably the magnets are circular. FVeferably the coils are circular. FVeferably the diameter of each magnet is approximately equal to the internal diameter of the coils. FVeferably the internal diameter of the coils is substantially one-third of the outer diameter of the coils. I n a preferred configuration, the spacing between adjacent magnets is such that in rotation when one magnet is positioned over the leading perimeter of a coil, the adjacent magnet is positioned over the space between coils, and the next adjacent magnet passes over the trailing perimeter of the adjacent coil. With the construction of the generator of Figures 5A, 5B the turbine blades 131 can be of any desired length. It is envisaged that a plurality of such generators could be positioned in side by side relationship horizontally along a roof ridge or vertically down a wall.

The same components 1 10A, 11 OB can be used for both versions of generator described in Figures 4A, 4B and 5A, 5B leading to manufacturing economies.

An advantage of the invention is that as fluid flow which rotates the inner annular member is entirely within the area which is defined by the outer circumference of the outer annular member, there are no protruding rotating blades which can cause harm or injury. The generator of the invention is safe and compact.

The invention may take a form different to that specifically described above. For example the generator need not be part of a turbine such as described above and shown in the drawings.

Further modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

It will of course be understood that many variations may be made to the above- described embodiment without departing from the scope of the present invention.