1

A turbine

The present invention relates to a turbine for driving an electrical power generator by a flow of fluid, particularly, but not exclusively, wind or water flow.

Conventional wind turbines have efficiency deficiencies primarily because the drag on each generating blade always has a negative effect on the performance. The advantages of traditional wind farm propeller type systems are that they sit on one pole and can be steered into the wind flow. Traditional paddle wheel type designs usually rely on blades or paddles that are held on two chassis, one at each end and these chassis are the diameter of the rotating blades. This type of device whilst suitable for tidal or river flows where they can effectively be fixed and non directional are totally unsuitable for wind generation due to the large engineering mass and the impractical steering mechanism.

The present invention seeks to provide an improved turbine and, accordingly, provides a turbine including:

an electrical power generator; and

a turbine blade assembly including:

a main shaft having a main, longitudinal axis;

one or two hubs rotatably mounted on the main shaft so as to be rotatable about the main axis;

a plurality of elongate blades rotatably mounted on each hub and which extend outwardly from the same side of the respective hub at the same angle to the main shaft and which are disposed rotationally symmetrically on the hub; and a blade rotation gearing which couples each blade to the main shaft so that each blade rotates 1 80° relative to hub for each 360° rotation of the hub relative to the main shaft; and in which

each hub is coupled to the electrical power generator so that rotation of each hub on the main shaft causes the electrical power generator to generate electricity. For the purposes of the following description it will be assumed the support shaft is vertical and that the fluid flows horizontally past the turbine, and which is as illustrated in the accompanying drawings in which the same features are given the same reference numerals.

The direction of rotation of each elongate blade relative to the hub on which it is mounted is in the opposite rotational sense to the direction of rotation of that hub on the main shaft.

The rotation of the blades on the hub(s) provides that each blade presents a larger area to the fluid when moving generally with the fluid and a smaller area when moving generally against the fluid flow resulting in net torque acting on hub(s) to rotate the main shaft.

The present invention has the advantages of traditional wind turbine single pole fixtures with a steerable blade hub but, because the blades are angled out from a central hub, it additionally gains all of the advantages of a self-feathering paddle wheel design whose efficiency is far superior. This is due to the fact that the blade is geared such that when a blade is moving in the direction of the flow at the top of its rotation it is angled to produce maximum drag and when it is moving towards the flow they are angled to produce minimum drag. It is not essential that the maximum drag effect is at the top of the rotation cycle but this is the most likely scenario since the wind flow is normally greater at the higher point of a wind generator and this is where it is advantageous to obtain a greater turning torque from the drag on the blades.

This invention is different from other known paddle wheel designs by being able to use a small central hub which can be easily mounted on one single pole and where the hub assembly can be easily steered to orientate to the wind. Also because the central hub can be so much smaller than the two hubs of a traditional water wheel type design there is lot of power wasted through rotating the mass of the hub at such a relatively small radius. The other advantage of the present invention is that since the proportion of mass of the tip of the blades can be relatively low, the unit can react to gusting far better. Also, since 30% of the blades rotation is using the drag from the flow then in gusting conditions, this all adds to the power extracted as opposed to a conventional propeller type unit where efficiency is lost through the blades not being able to react to the gusting flow via their pitch angle. A turbine according to the present invention may have two hubs in which case the main shaft is rotatably mounted on the support shaft with the main axis at a right angle to the axis of the support shaft. Such a turbine operates with the main shaft at right angles to, and in the plane of, the fluid flow. This orientation may be achieved by the forces acting on the blades which are in stable equilibrium in relation to the fluid flow the alignment of the hubs rotating on the support shaft to maintain this orientation as the direction of the fluid flow changes. Conveniently, the turbine may further include a vane connected the hubs to assist in the orientation of the main shaft at a right angle to the fluid flow.

Alternatively, servo motor steering may be employed to align the hubs the wind direction.

Rotation of the blades relative to the hub(s) on which they is mounted may be effected by gearing the blades to a common drive gear wheel fixed to the main shaft or other suitable drive means.

The turbine may include an output shaft for connection to an electrical power generator and which is rotated by the rotation of the hub(s) relative to the main shaft but any suitable means for driving an electrical power generator by the rotational movement of a hub relative to the main shaft may be employed.

Each hub may include a ring gear fixed to an overarching blade support member in which the blades are rotatably mounted, the ring gear being geared to the output shaft whereby the output shaft is rotated as the hub rotates relative to the main shaft.

In a further embodiment of the turbine according to the present invention, there is a single hub and the main shaft is rotatably mounted on the support shaft with the main axis parallel to the axis of the support shaft. In this embodiment the main shaft is always vertical and so always at a right angle to a horizontal fluid flow. The correct angular position of the main shaft on the support shaft as the flow direction of the fluid changes can be achieved through the use of servo motor connected to the main shaft. Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings of which:

Figure 1 is an isometric schematic view of an exemplary first embodiment of the present invention;

Figure 2 is an isometric schematic view of the embodiment of Figure 1 with protective cowlings removed;

Figure 3 is a isometric schematic view of part of the gear mechanism of the embodiment of Figure 1 ;

Figure 4 is a isometric schematic view of part of the gear mechanism of the embodiment of Figure 1 ;

Figure 5 is a cross-sectional part schematic view of part of the gear mechanism of the embodiment of Figure 1 ; and

Figure 6 is a side schematic view of an exemplary second embodiment of the present invention.

Referring to Figure 1 , a first exemplary embodiment of the invention is a wind turbine 2 which includes a turbine blade assembly 4 rotatably mounted to the top end of a vertical pole 6, and whose bottom end is fixed in the ground (not shown) , by means of a support shaft 8. The assembly 4 includes a pair of hubs 10 each mounted on a common main shaft 1 2 (see Figures 2 to 5) which is welded to the top of the support shaft 8. Each of the hubs 10 has rotatably mounted on it three elongate blades 1 4 which extend outwardly from the hub 1 0 on which is mounted at the same angle to the axis (A) of the main shaft 1 2.

The blades 14 on a given hub 1 0 are arranged with their respective axes rotationally symmetrically positioned. In the illustrated embodiment there are three blades on each hub but two or more than three blades may be used.

In use, wind blowing across the turbine causes both hubs 1 0 to rotate by virtue of the net torque applied to the blades 1 4. Blade rotation gearing (see particularly Figure 4) couples each blade 1 4 of a hub 1 0 to the main shaft 1 2 so that each blade 14 rotates 1 80° relative to the respective hub 10 as the hub 10 rotates 360° around the main shaft, 1 2, and in the opposite rotational sense (rotational directions D and R in Figure 1 ) and as will be described in detail below.

The turbine blade assembly 1 0 includes covers 1 6 to protect the internal parts of the turbine assembly as shown in Figure 1 . Figure 2 is a view of the turbine assembly 4 of Figure 1 with the covers 1 6 removed.

The turbine blade assembly 4 also includes a wind vane 1 8 mounted at the outer end of a shaft 20 and whose inner end is welded to the support shaft 8. As shown in Figure 1 , the wind vane 1 8 orientates the turbine blade assembly 4 so that the rotational axis of the hubs 10, which is coincident with the axis A of the main shaft 1 2, is maintained at right angles to the wind direction W.

An electrical power generator 22 is also mounted on the shaft 20 as shown in Figure 3 and Figure 5 with a protective cover 24 (not shown in Figure 2 for reasons of clarity) .

Referring to Figures 2 to 5, particularly, each hub 1 0 includes a main support ring 30 on one side of which is bolted a ring gear 32 and on the other side of which is bolted a three armed, generally convex, support 34 which overarches the support ring 30. The support ring 30 is fixed to a spoked frame 36 with a central annular ring 38 which is bolted to a bearing 40 with ball race 42 rotatably mounted on the main shaft 1 2 (see Figure 5) . Also referring to Figure 5, the support 34 includes, at its apex, a bearing 44 also rotatably mounted on the main shaft 1 2. The complete assembly of support ring 30, ring gear 32 and support 34 is rotatable as a unit on the main shaft 1 2 and retained on it by a threaded fastener 46.

Referring particularly to Figures 4 and 5, each blade 1 4 has a stub shaft 48 which is rotatably mounted on the support 34 by means of bearings 50 and retained in place by a threaded fastener 52 which also retains in place a gear wheel 54 which is keyed to the stub shaft 48 so as to be rotatable with the stub shaft 48 and so, also, the blade 14. Mounted on the main shaft 1 2 is a bevel gear 56 keyed to the main shaft 1 2 so as to be fixed relative to it. Also rotatably mounted to the support 34 are three pairs of stacked, coaxial, gear wheels 60, 62. The gear wheel 60 nearer the support 34 of each pair is engaged with a respective gear wheel 54 fixed to a blade 14, the gear wheel 62 of each pair further away from the support 34 is engaged with the bevel gear 56 fixed to the main shaft 1 2. The gear wheels are sized such that as support 34 of a hub 10 rotates 360° relative to the support 34 and hub 1 0.

Referring now to Figures 3 and 4, the generator 22 is mounted on a support beam 62 fixed to the side of shaft 20. A driven shaft 60 is supported by a bearing 64 attached to the support beam 62 and whose end is rotatably mounted to a bearing 68 which is supported by a rod 70 fixed to shaft 8. A bevel gear 72 is keyed to the end of a driven shaft 60.

The bearing 68 rotatably supports a through shaft 74 on which are fixed a pair of gear wheels 76 and a single bevel gear 78 which is engaged with bevel gear 72. The gear wheels 76 are engaged with respective ones of ring gears 32.

Referring now to Figure 6, there is shown a second embodiment of the present invention in which a single turbine blade assembly 80 is rotatably mounted on a support 82. The hub 84 is as a hub 1 0 of the first illustrated embodiment except the main shaft 1 2 is vertically aligned and is used to rotatably mount the hub 84 on the support rather than the shaft 8 of the first embodiment. The ring gear 32 of this embodiment is directly geared to the driven shaft via gear wheel 90 fixed to the driven shaft 20 of the electrical power generator 22 located at the top of support 82. The hub 84 is supported at the top of the shaft 82 on a thrust bearing 1 00 and coupled to a vertically extending shaft 1 02 within the shaft 82 by which the rotational position of the hub 84 can be controlled. A servo mechanism 92 rotates the main shaft 1 2 via gear wheels 94 and 96 the latter being connected to the shaft 1 02 via a slot 98 in the support 92 so that the blades are aligned relative to the wind direction as described with reference to the first embodiment.

The embodiments of the present invention shown in Figures 1 to 5 operate as follows.

Referring to Figures 1 to 5, when the wind blows in direction W of sufficient strength, the vane 1 8 assists in rotating the turbines blade assembly 4 so it is orientated with the main shaft 1 2 at right angles to the direction W. The blades are arranged so that when each blade is at the top of its rotational cycle it presents its broadest section to the wind, as shown in Figure 1 will present its edge to the wind when at the bottom of the rotational cycle by virtue of the above-described gear chain between each blade 1 and the main shaft 1 2. This results in the hubs 1 0 rotating in the direction D and the blades 1 4 rotating in direction R, as shown in Figure 1 . As the hubs 10 rotate the ring gears 32 drive the driven shaft 60 of the electrical power generator 22 via the chain of gears 68, 78 and 72.

The embodiment of Figure 6 operates in a similar fashion except that the main shaft's orientation relative to the wind direction is controlled by means of the servo motor 92 which is controlled by a controller (not shown) in response to changes in the wind direction. The servo motor 92 operates to maintain the rotational position of the main shaft 1 2 relative to the wind direction.

Particular advantages of the embodiment of Figure 6 are that there is no need to rotate a large assembly to change the orientation of the turbine blade assembly to match a changed wind direction change. Because the servo 92 and power generator 22 can be fixed to the main support pole 82 the electrical wiring (not shown) is also fixed and doesn't need to move with the hub1 0 or main shaft 1 2. This means that the hub 1 0 can rotate multiple 360 degrees in the same rotational sense without the need for electrical connections to run on contacts. Also, with this vertical design the tips of the blades will be in the fastest air flow which is generall at the highest point above the ground for a wind turbine..