WO2010148443A1

WO2010148443A1 - Vertical axis wind turbine

Info

Publication number: WO2010148443A1
Application number: PCT/AU2010/000786
Authority: WO
Inventors: Peter Jansson
Original assignee: Peter Jansson
Priority date: 2009-06-24
Filing date: 2010-06-24
Publication date: 2010-12-29

Abstract

A vertical axis wind turbine module (10) adapted to rotate about a vertical axis, the module including; a rotor (14) having a plurality of turbine vanes (16), the rotor being adapted to be rotated about the axis by a driving force exerted by incident air engaging the vanes; a pair of module transmission components being axially spaced from the rotor, one below and the other above the rotor (upper 22, lower not shown); at least one transmission means spaced radially from the axis (42,44), the at least one transmission means interconnecting the rotor and each transmission component such that rotation of the rotor about the axis causes rotation of the at least one transmission means and hence rotation of the module transmission components about the axis.

Description

Vertical Axis Wind Turbine

Field of the Invention

This invention relates to a vertical axis wind turbine a module for use in such a turbine.

Background to the Invention

The discussion of the prior art in this specification is not intended as, and should not be taken as, an admission that it was published, or part of the common general knowledge in Australia at the priority date of the present specification.

Wind turbines can be classified by a number of their characteristics. A typical distinction is made between horizontal axis wind turbines (hawt), wherein the incident wind is designed to be directed along the axis of rotation of the rotor, and vertical axis wind turbines (vawt), wherein the incident wind is designed to be directed perpendicularly to the axis of rotation of the rotor.

The present invention is in relation to the second category, being the vertical axis wind turbines.

According to one earlier design of vertical axis wind turbine, the vertical drive shaft of the turbine was mostly unsupported laterally, and required two or more bearings suitable for withstanding axial and lateral loads. This has resulted in such turbines being particularly limited in height and, for such turbines used for electricity generation, also limited in power output - for example, having typical running power outputs of 1 to 2 kW and maximum outputs of 5 to 10 kW.

Another known type of vertical axis wind turbine included a support framework which was adapted not only to support the shaft but also to house top and bottom bearings. Such turbines could be of far greater heights than earlier turbines. However, even in these cases, the drive shafts were in the form of relatively small-diameter central shafts which were subject to increasing torsional deformation as the height of the turbines increased. This resulted in a limited size and capacity for such types of turbine. A further known type of vertical axis wind turbine has vanes which define passageways to allow incident air to pass through the turbine which is beneficial for the operation of the turbine. However, this type of known turbine employs a central drive shaft which constitutes an obstacle to the passage of the incident air. This problem is exacerbated the higher the turbine is, as this requires a drive shaft of greater diameter, which therefore constitutes a greater obstacle to the passage of the air.

Another problem with certain known vertical axis wind turbines is that the rotors which include the turbine vanes are often of such large dimensions that road transport of the rotors is impractical.

It is an object of the present invention to overcome or ameliorate one or more of the disadvantages of the prior art, and/or to provide a useful alternative thereto.

Summary of the Invention

According to a first aspect of the invention there is provided a vertical axis wind turbine module adapted to rotate about a vertical axis, the module including: a rotor having a plurality of turbine vanes, the rotor being adapted to be rotated about the axis by a driving force exerted by incident air engaging the vanes; a pair of module transmission components being axially spaced from the rotor, one below the rotor and the other above the rotor; at least one transmission means spaced radially from the axis, the at least one transmission means interconnecting the rotor and each module transmission component such that rotation of the rotor about the axis causes rotation of the at least one transmission means and rotation of the module transmission components, about the axis.

In a preferred embodiment, the vanes are configured such that passageways are defined between adjacent vanes, to allow the passage of the incident air therethrough.

In a preferred embodiment, the section of the passageways towards the axis of rotation are minimally obstructed by the at least one transmission means. In a preferred embodiment, the vanes are configured for the incident air to exert said driving force at least partially by an aerofoil lift effect.

In a preferred embodiment the rotor includes separable sections, each section including one vane.

In a preferred embodiment, the at least one transmission means includes a plurality of transmission elements arranged about the axis. The transmission elements are preferably arranged in a circular formation with the axis extending through a centre of the circular formation.

In a preferred embodiment, the module transmission components include first engagement formations for engaging a plurality of the transmission elements, for fixing the module transmission components to the transmission elements in rotation about the axis.

In a preferred embodiment, the rotor includes second engagement formations for engaging with a plurality of the transmission elements, for fixing the rotor to the transmission elements in rotation about the axis.

In a preferred embodiment, the rotor includes an upper vane plate and a lower vane plate, the vane plates partially sandwiching the vanes between them.

In a preferred embodiment, the module includes a first rotor spacer for spacing one of the module transmission components from the rotor, and a second rotor spacer for spacing the other of the module transmission components from the rotor. Preferably, each rotor spacer includes third engagement formations for engaging with a plurality of the transmission elements, for fixing that rotor spacer to the rotor in rotation about the axis.

In a preferred embodiment, each transmission element is an elongate element, which is preferably a hollow tube. In this case, each engagement formation includes an aperture adapted to accommodate a said hollow tube therethrough. In a preferred embodiment, the module includes at least one module securement component for urging the module transmission components towards each other to compressive^ hold the rotor therebetween. Preferably, the at least one module securement component includes at least one elongate tensile securement element, preferably a rod or flexible cord, which is adapted to extend through at least one said hollow tube.

According to a second aspect of the invention there is provided a vertical axis wind turbine, the turbine including a plurality of turbine modules according to the first aspect of the invention, the modules being arranged axially with respect to one another.

According to another aspect of the invention, the rotor is provided with foils. According to a preferred embodiment, the foils operate in cooperation with the rotor vanes and may assist with the upwind characteristics of the vane.

According to a preferred embodiment, the foils are provided proximate the outer circumference of the rotor vanes.

In one embodiment, the foils extend axially substantially across the extent of a rotor.

In another embodiment, the foils extend axially substantially across the extent of a module.

In yet another embodiment, the foils extend axially substantially across the extent of the rotating portion of the operable vertical axis wind turbine.

According to one embodiment, the foils are fixed with respect to the corresponding vanes.

According to a preferred embodiment, the foils are adjustable with respect to the vanes.

According to a preferred embodiment, the foils are angularly adjustable with respect to the vanes. According to a preferred embodiment the foils thereby attached are assisted by a further aerodynamic surface that may not be directly connected to the rotor and which can direct the incident wind in primarily two directions one of which provides enhancement to the rotation of the rotor.

In this specification, references made to "vertical" are due to the conventional labelling of a vertical axis wind turbine and this invention is not limited to the exact vertical, but encompasses other angles to the vertical as would be understood by those skilled in the art. For example a "vertical" axis wind turbine may be mounted horizontally, such as from the side of a building or structure, but functions optimally when the incident wind is perpendicular to the axis of rotation.

Brief Description of the Drawings

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is an exploded schematic perspective view of part of a vertical axis wind turbine module according to an embodiment of the invention;

Figure 2 is a schematic plan view of a rotor of the module of Figure 1 ;

Figure 3 is a schematic side view of a vertical axis wind turbine having a plurality of modules as shown in Figure 1 ;

Figure 4 is a schematic perspective view of part of a vertical axis wind turbine module according to another embodiment of the invention; and

Figure 5 is a schematic perspective view of part of a vertical axis wind turbine module according to yet another embodiment of the invention,

Figure 6 is an exploded schematic perspective view of part of a vertical axis wind turbine module having a plurality of rotors according to another embodiment of the invention. Figure 7 is a schematic side view of a vertical axis wind turbine having a plurality of modules as shown in figure 6.

Figure 8 is a schematic side elevation of a vertical axis wind turbine having positions for two rotors.

Figure 9 is a schematic perspective view of part of a vertical axis wind turbine module according to yet another embodiment of the invention.

Figure 10 is a schematic perspective view of a rotor of the module according to yet another embodiment of the invention.

Detailed Description

Referring to Figure 1 , there is shown a vertical axis wind turbine module 10 which is adapted to rotate about a vertical axis 12. '

The module 10 includes a rotor 14 which has four turbine vanes 16, an upper vane plate 18, and a lower vane plate 20. The vanes 16 are partially sandwiched between the vane plates 18, 20.

The module 10 also includes a pair of module transmission components in the form of an upper transmission plate 22 and a lower transmission plate (not shown). The transmission plates 22 are axially spaced from the rotor 14 by an upper rotor spacer 26 and a lower rotor spacer 28, so that the upper transmission plate 22 is above the rotor and the lower transmission plate is below the rotor.

Extending from the upper transmission plate 22 is a short shaft 30, which is joined to a drive spline 32. The short shaft 30 extends though a bearing 34 which is contained in a bearing housing 36. Extending from the bearing housing 36 are mounting arms 38 for mounting the bearing housing, and hence the module 10, to a suitable support structure (not shown). Similar components are provided on the lower transmission plate that may be seen in the similar embodiment shown in Figure 8. ¹

Also mounted on the short shaft 30 is a disk brake unit 40 with a disk brake (not shown) configured to engage the short shaft.

There are provided a number of transmission elements in the form of twelve upper elongate, hollow, high tensile, thin-walled, hardened steel tubes 42, and twelve similar lower tubes 44. The upper tubes 42 extend through, and are therefore engaged with, engagement formations in the form of equally spaced apart apertures 46 in the upper rotor spacer 26, apertures 47 in the upper vane plate 18, and apertures 49 in the upper transmission plate 22. Similarly, the lower tubes 44 extend through equally spaced apart apertures 48 in the lower rotor spacer 28, apertures in the lower vane plate (not shown) and apertures in the lower transmission plate (not shown). Each upper tube 42 is aligned with a respective lower tube 44.

The tubes 42, 44 are arranged in circular formations with the axis 12 extending through the centres of the circular formations. The tubes 42, 44 interconnect the rotor 14 with each of the transmission plates 22 via the rotor spacers 26, 28, and thus fix the transmission plates and rotor spacers in rotation to the rotor.

The transmission plates 22, rotor spacers 26, 28 and rotor 14 are held together by securement components in the form of high tensile cables 50 (only a portion of one such cable being shown). Each cable 50 extends through a respective upper tube 42 and aligned lower tube 44, and is tightened in place by nuts 52 which are secured to threaded ends 54 of the cable and which engage cable spacers 56 on the cable. The cables 50, when secured in this manner, hold the transmission plates 22, rotor spacers 26, 28 and rotor 14 under compression.

Although only one rotor 14 is shown in Figure 1 , which is disposed between the upper and lower rotor spacers 26 and 28, one or more additional rotors may be provided, as shown in Figures 6, 7 and 8, each pair of adjacent rotors being spaced apart by a similar rotor spacer. In this case, the rotational position of the rotors may be rotationally staggered so that the vanes of each pair of adjacent rotors are not aligned with each other, as discussed further, below.

Referring to Figure 2, the vanes 16 of the rotor 14 are discussed in more detail. The rotor 14 is formed of four separable sections 14.1 , 14.2, 14.3 and 14.4, each including one of the vanes 16. The sections 14.1 , 14.2, 14.3, 14.4 are held together by the tubes 42, 44 which pass through the apertures 47 in the upper vane plate 18 and similar apertures in the lower vane plate 20 of the rotor. The rotor shown in Figure 2 has a rotor plate which is of a star-fish shape and not round as shown in Figure 1 , and it does not show the apertures for the steel .tubes.

The vanes 16 are configured such that passageways 58 are defined between adjacent vanes. This allows the flow of air due to wind that engages the rotor (incident air) to pass through the rotor 14.

The vanes 16 are configured as aerofoils. Thus, the incident air engaging the vanes 16, as represented by the arrows 60, can be deflected to follow the convex face 62 of a vane thereby effecting an aerofoil lift force on the vane, as described in more detail below.

In use, one or more modules 10 may be used to form a vertical axis wind turbine 64 as shown in Figure 3. Where there is more than one module 10, the modules are connected to one another, axially, by the adjacent drive splines 32 of the successive modules. The intermediate drive splines 32 of each pair of adjacent modules 10 can be engaged with each other by suitable spline connectors (not shown) which are adapted to transmit rotational force from one spline, and hence one module, to the next.

Those splines 32 that are not between adjacent modules 10 (i.e. the two splines of a particular module where only one module is used, or the two end splines of a combination of modules), can be connected to suitable power take offs (not shown) depending on the purpose for which the turbine 64 is used (e.g. electricity generation, pumping, etc).

The turbine 64 is positioned in the location where wind power is to be harnessed. Wind that engages a rotor 14 (incident air), as represented ^'by the arrows 60, is caused to deflect by the vane 16 that is positioned most upstream relative to the other vanes (upstream vane), so as to follow the convex face 62 of that vane, and is channelled through the passageways 58 as indicated by the arrows 66. The force of .the air moving over the convex face 62 exerts an aerofoil lift force on the upstream vane 16 thereby causing the rotor 14 to rotate in the direction indicated by the arrow 68 in Figure 2.

It will be appreciated that each vane 16 has an optimum angle relative to the direction of the incident air 60 at which the lift force of the air flow on the vane is at a maximum. As the rotor 14 rotates, the angle of the vane 16 relative to the incident air 60 changes and the lift force reduces. However, further rotation of the rotor 14 causes the next vane 16 to move into position to become the upstream vane, and so that the angle of that vane relative to the incident air 60 is the optimum angle, with a corresponding increase in the lift force. This repeatedly increasing and decreasing lift force causes a pulsing effect on the rotor 14.

To compensate for, and minimise, this pulsing effect, in a module 10 having more than one rotor 14, the positions of the rotors are rotationally staggered with respect to one another about the axis 12 so that their vanes 16 are not aligned. This staggering is enabled by the use of the tubes 42, 44 and equally spaced apertures. During assembly of the module 10, the rotational position of each rotor 14 relative to each other rotor, and relative to the rotor spacers 26, 28 and transmission plates 22, 24, can be determined. The rotors are only fixed in rotational position relative to these components when the tubes 42, 44 are inserted through the respective apertures.

As a result of the ability to stagger the rotors 14, where the position of one rotor is such that the lift force of the incident air 60 on the upstream vane 16 is at a minimum, the upstream vane of the next rotor may, for example, be positioned at its optimum angle so that the maximum lift force is exerted on that rotor. This illustrates how the above- mentioned pulsing effect may be at least partially neutralised.

Similar effects may be achieved by staggering the rotational position of successive modules 10 in turbines, such as the turbine 64, using a plurality of modules, The passageways 58 allow the incident air 60 effectively to flow freely through each rotor 14, to minimise any hampering effect that the air flow might otherwise have on the rotation of the rotor. Indeed, while the main rotational force exerted on the rotor 14 is due to the aerofoil lift effect on the convex face 62 of the upstream vane 16, the incident air 60 that passes through the passageways 58 can also exert a direct driving force on the concave face of the opposite vane 16, to further contribute to the rotational force on the rotor.

The preferred embodiment of the invention as described has four vanes 16 for each rotor 14. This is considered to be an advantageous number of vanes for minimising the pulsing effect, providing a relatively large throat area 70 for ingress of the incident air 60 into the passageways 58, and assisting to achieve a laminar flow of the air.

Reference is now made to the use of the tubes 42, 44 as transmission elements for transmitting rotational force from each rotor 14 to the transmission plates 22, and hence to the power take offs. It will be appreciated that the tubes 42, 44 are used as an alternative to a drive shaft. It will also be appreciated that, if a central drive shaft were used instead, it would not be feasible for such a shaft to have a radius as large as the radial spacing of the tubes 42, 44 from the axis 12. Indeed, the radial spacing is significantly greater than the maximum feasible radius for any such shaft. Such a relatively narrow drive shaft would suffer from a high degree of undesirable torsional distortion, particularly if the turbine were of a relatively great height.

However, the effect of the combination of tubes 42, 44 as force transmission elements is similar to that of a drive shaft having a radius equal to that radial spacing. Thus, the use of the tubes 42, 44 as force transmission elements provides an effective way to minimise the undesirable torsional distortion to which a narrow drive shaft would be subject, while avoiding the need for an impractically large-diameter shaft.

They also facilitate the provision of the passageways 58 as described above. If a relatively large central drive shaft were used instead, it would constitute an obstacle to the free passage of the incident air 60 through the passageways 58. The separable nature of the four sections 14.1 , 14.2, 14.3, 14.4 of each rotor 14 as described above allows the rotor to be disassembled for transport. Considering that each vane 16 can .be in the order of three metres in length, this can be a significant practical benefit.

The invention allows for a turbine 64 with a plurality of modules 10, each module having its own bearing 34, disk brake units 40 as well as housings 36 which are supported by means of the mounting arms 38 on the support structure (not shown). This has the further advantage of distributing the support load on the support frame across the bearing housings, and distributing the braking forces when braking occurs. This in turn assists in enabling a large number of modules 10 to be used in a particular turbine 64 so that the turbine can be of a height of 40 m to 60 m or higher. Thus, where the turbine 64 is used for generation of electricity, power outputs of up to 500 kW or greater may be achievable.

As an alternative to the cable 50 for securing the various components of a module 10 together as described above, other tensioning means may be used such as solid rods, rated cables, threaded rods, wire rope, synthetic fibre chords, or any other suitable means.

Also, as an alternative to having the components of each module 10 held together in the manner described above with reference to the cables 50, compression cages may be used. One such cage 72 is illustrated in Figure 4. This cage 72 includes long tubes 74 which extend through the upper and lower transmission plates 22 (as opposed to having upper and lower tubes 42, 44 as described with reference to Figure 1). The long tubes 74 are all interconnected by flexible high tensile chords 76 which urge the long tubes radially inwards towards the central axis 78.

There are two high tensile chords 76 extending through each long tube 74 so that the chords cross over each other between the long tubes.

Another such cage 80 is illustrated in Figure 5. In this cage 80, there are only four long tubes 82 similar to those 74 of Figure 4, with the remainder of the tubes being as in the embodiment of Figure 1. In addition, there are transmission plates 84 with skirts 86 to facilitate containment of the other components of the module between the transmission plates.

The embodiment shown in Figure 6 is similar to that of Figure 1 such that similar numbers are used for similar components. However in this embodiment the module 10 includes two rotors 14 and 14b each of which has four turbine vanes 16 and 16b, respectively. The upper transmission plate 22 is axially spaced from the rotor 14 by an upper rotor spacer 26 and a lower rotor spacer 28 (in respect of the upper rotor 14) forms the upper rotor spacer of the second rotor 14b. This results in the upper transmission plate 22 being above both of the rotors 14 and 14b, and, the lower- transmission plate (not shown) being below both of the rotors 14 and 14b. While the embodiment shown has the vanes 16b of the second rotor 14b angularly aligned with the vanes 16 of the first rotor 14, it is preferred if each rotor is out of angular alignment with its neighbouring rotors.

It should be appreciated by one skilled in the art that further rotors may be added to the module in a similar fashion and Figure 7 shows a module having 4 rotors.

Referring now to Figure 8 there is shown an arrangement similar to that of Figure 6 wherein the vertical axis wind turbine is provided with two rotors, though only the topmost rotor 14 is shown in this illustration. The vanes of the rotor 16 may be retained by compressive forces introduced by the compression cage 72 arrangement similar to that of Figure 4 acting on the upper vane plate 18 and the lower vane plate 20 sandwiching the vanes 16 therebetween.

Provided at the upper end of the apparatus is mounted on the short shaft 30 a disk brake 40 with a disk brake calliper 41 configured to mount to the mounting arms 38 and to engage the disk brake 40 and provide selectable retardation of the rotating apparatus. A similar arrangement is provided at the lower end of the apparatus. Figure 9 shows an alternative compression cage arrangement 90 compared to cages 72 and 80 previously described. In this embodiment the compression cage 90 is provided with elongate members 92 that are configured to guide a tension element 96 within their extent. The elongate members 92 are optionally provided with a separable junction 94 that would facilitate easier manufacture and transportation of the compression cage 90 components. In this way the compression cage 90 halves are held together by the compressive forces of the elongate members 96. Further elongate members 98 that may be used for engaging other rotors (not shown) are terminated at 100 without extending through the compression cage 90.

in a further embodiment of the compression cage (not shown) the elongate members _, may be separable from the end portions of the cage, such that the compression cage may be further collapsed during transportation.

A further embodiment of a rotor of the present invention is shown in Figure 10. In this embodiment the rotor is similar to the rotor shown in Figure 2. The rotor of Figure 10 is provided with elongate foils 17 at the outer circumference of the rotor plates 18 and 20. The foils 17 are connected at their longitudinal extremities to the rotor plates. Preferably the connection means provides for the adjustment of the foils 17 with respect to the vanes 16. In a preferred embodiment the foils 17 may be dynamically adjusted while the turbine is operated to optimise the performance of the turbine. Said adjustment may include any combination of adjustment along the leading edge of the main vane, angular adjustment of the foil (angle of attack), and/or adjustment of the radius of rotation of the foil about the axis of rotation. In operation the foils 17 enhance the windward rotation of the turbine and thereby reduce the counter-rotation effects of the prevailing wind on the reverse side of the turbine vane 16.

It would be appreciated by one skilled in the art that the present invention is capable of being implemented in conjunction with other means for improving the performance of a vertical axis wind turbine. One such means (not shown in the drawings) is provided by a further aerodynamic surface that may not be directly connected to the rotor and which can direct the incident wind in primarily two directions one direction of which provides enhancement to the rotation of the rotor including increased incident wind velocity and reduced resistance to upwind vanes through a venturi effect.

Although the invention has been described with reference to particular embodiments above, it will be appreciated by those skilled in the art that the invention is not limited to those embodiments, but may be embodied in other forms as well.

Claims

1. A vertical axis wind turbine module adapted to rotate about a vertical axis, the module including: a rotor having a plurality of turbine vanes, the rotor being adapted to be rotated about the axis by a driving force exerted by incident air engaging the vanes; a pair of module transmission components being axially spaced from the rotor, one below the rotor and the other above the rotor; at least one transmission means spaced radially from the axis, the at least one transmission means interconnecting the rotor and each module transmission component such that rotation of the rotor about the axis causes rotation of the at least one transmission means and hence rotation of the module transmission components, about the axis.