A turbine deflector shield.

Abstract

A shield 1 for deflecting airflow around a turbine 9 with turbine blades, the shield includes a deflector shield 7, and a wind vane 3. The wind vane is configured to rotate around the turbine under th

Description

The present invention is in the field of deflector shields for use alongside wind turbines, in particular vertical axis wind turbines. Background There has been a conscious change in recent years, particularly by homeowners, towards adopting more renewable energy sources in place of traditional fossil fuels based sources for generating electricity. This may be for environmental reasons with an aim to reduce one's carbon footprint or for financial reasons given the high price of oil, gas and electricity at present. One such renewable energy source that has seen a rise in its popularity, especially in residential settings, is a wind turbine. However, like many other wind energy sources, these turbines are prone to producing loud noise and can be less efficient than fossil fuel alternatives that have much more established infrastructures. There is yet to be disclosed a mechanical means of passively reducing the turbulence on said blades in a bid to reduce noise pollution, all whilst increasing the efficiency and the power produced by the turbine as a whole. Aspects of the present invention aim to address at least some of these issues. Statements of Invention Aspects of the invention are set out in the independent claims. Optional features are set out in the dependant claims. In accordance with a first aspect of the invention there is provided a shield for deflecting airflow around a turbine comprising turbine blades, wherein the shield comprises: a deflector shield; and a wind vane; wherein the wind vane is configured to rotate around the turbine under the resultant force of the airflow incident on the wind vane; wherein the wind vane is configured to rotate with the resultant force into a first position; wherein the deflector shield is configured to be driven by the rotation of the wind vane and rotate around the turbine. Advantageously, this arrangement utilises a low complexity, easy to assemble and economical and passive infrastructure that implements a deflector shield onto a turbine. The arrangement may be easily modified to fit turbines of varying sizes and types due to its simplistic, modular and adjustable nature. Optionally, wherein when the wind vane is in the first position, the deflector shield is configured to be positioned such that it screens at least a portion of the turbine blades that are rotating against the direction of the resultant force of the airflow. In such a configuration, the resistive force of the airflow on the turbine is often substantially reduced leading to an increase in the turbine efficiency. The physical barrier of a deflector shield present between the airflow and the turbine blades that rotate against may it also significantly reduce the presence of turbulent airflow over the blades leading to less noise. Optionally, wherein the rotational path of the turbine comprises a first portion and a second portion; wherein the turbine blades are configured to rotate against the direction of the resultant force of the airflow in the first portion; wherein the turbine blades are configured to rotate with the direction of the resultant force of the airflow in the second portion; wherein the deflector shield is configured to screen at least a section of the first portion when the wind vane is in the first position. Screening the turbine blades that are in the first portion may substantially reduce the resistive forces acting on the turbine from the airflow travelling against their direction of motion. This may lead to an increase in turbine efficiency and power output. Such screening may also reduce noise by reducing the turbulent airflow over the turbine blades in the first portion. Additionally, the airflow that drives the turbine blades in the second portion may be entirely unaffected. Therefore, there may be no reduction in turbine rotation speed with the implementation of the current arrangement. Optionally, wherein the deflector shield is configured to be positioned such that a section of the second portion is exposed to the airflow from the resultant force direction when the wind vane is in the first position. Exposing a portion of the second portion may ensure that a driving force onto the turbine blades from the resultant airflow direction is continuously provided. This may allow for continuous motion of the turbine blades leading to no loss in power output of the turbine. Optionally, wherein the first position is a position in which the plane of the wind vane is parallel with the direction of the resultant force of the airflow. Advantageously, the wind vane may continuously and immediately correct its orientation to align its plane with the resultant airflow direction. Such a parallel orientation is also passively achieved. Optionally, wherein the wind vane is configured to settle into the first position; wherein the first position is a position of stable equilibrium for the wind vane. Advantageously, by settling into a positon of stable equilibrium, there is often no requirement for a dampening means which may add additional complexity to the system. Optionally, wherein the deflector shield is configured to settle when the wind vane is settled; wherein the position settled into by the deflector shield is a position of stable equilibrium for the deflector shield. Advantageously, since the wind vane settles with a consistent parallel orientation with respect to the resultant airflow direction, constraining the rotation of the deflector shield with that of the wind vane prevents the need of introducing additional dampening and control means for the deflector shield, as it is naturally controlled with the wind vane. Optionally, wherein the shield comprises a rigid connection between the wind vane and the deflector shield; wherein the rigid connection is configured to constrain the angular distance between the deflector shield and the wind vane such that the angular distance is constant throughout the rotation of both the wind vane and deflector shield. Advantageously, this arrangement may be used to calibrate the distance of the deflector shield with that of the wind vane for a given turbine diameter such that, when the wind vane settles into its first position, the deflector shield also consistently settles into the desired positon with respect to the resultant airflow direction. The angular distance of the connection can be set / adjusted with ease prior to use such that it is sized for a specific turbine diameter. The rigid connection also ensures there is no loss of energy / movement between the wind vane and the deflector shield. Optionally, wherein the angular distance at which the deflector shield and wind vane are held at is such that in the first positon of the wind vane, the deflector shield screens a section of the first portion of the turbine. This arrangement negates the need of introducing controlling means as the deflector shields orientation is calibrated and sufficiently controlled by this simply rigid connection with the wind vane. Optionally, wherein the angular distance at which the deflector shield and the wind vane are held at is such that the axis of the plane of the wind vane and the axis of the centre of the deflector shield are angularly separated. Advantageously, this offset between the wind vane and the deflector shield may allow the deflector shield to screen predominantly, or only, the blades rotating towards the resultant wind direction in some embodiments. Such an arrangement may also suit embodiments where turbine blades have trailing edges that extend into a first portion of the turbines rotational path and where these trailing edges are to be left exposed to the resultant wind direction. Optionally, wherein the leading vertical edge of the deflector shield is configured to be positioned such that the plane of the wind vane intersects it or is ahead of it; wherein the leading edge is the edge of the deflector shield closest to or partially screening the second portion when viewed from the direction of the resultant force of the airflow. Advantageously, such an arrangement ensures that the position of the deflector shield is biased and calibrated to screen predominantly the turbine blades in a second portion when the wind vane is in a first position. This reduces the resistive forces acting on the turbine blades and increases efficiency. Optionally, wherein the angle between the plane of the wind vane and a line connecting the centre of the turbine to the leading edge is pi radians. This may allow for a substantial area of the first portion of the turbine path to be screened and may be particularly suited for turbine with equally wide first and second portions. Optionally, wherein the shield comprises a primary frame. Advantageously, a frame may support the above-mentioned infrastructure of the present invention without transmitting mass onto the turbine. The structure of the frame may provide a clear distinction from that of the turbine. This may prevent damage on the frame from being transferred to the turbine. Optionally, wherein the primary frame is stationary about the turbine, and the wind vane is configured to attach onto the primary frame and rotate around the primary frame. In such arrangement, the primary frame is a non-moving part. This may allow for a more stable attachment between it and the turbine, which may result in the increased longevity of the primary frame due to less wear and tear that may be associated with an otherwise rotational relationship. Additionally, since the primary frame is also a load-bearing part, a stationary relationship may lower the probability of failure as compared to if it was a moving part. In this arrangement, the wind vane may only need to produce sufficient force to move itself and the deflector shield and not the primary frame, which may allow for a more responsive / sensitive deflector shield rotation. Optionally, wherein the deflector shield is configured to attach onto the primary frame such that the deflector shield is rotatable around it. Optionally, wherein the primary frame is configured such that the primary frame is rotatable around the turbine; wherein the wind vane rigidly attaches onto the primary frame such that it is stationary with respect to the primary frame; and wherein the rotation of the wind vane drives the rotation of the primary frame about axis of the turbine. Advantageously, this arrangement may allow for a more constraint and damped rotation of the all components around the turbine, as the force produced by the wind vane drives both the deflector shield and the frame. This may reduce likelihood of failure especially under high wind speeds where overly sensitive rotating components may experience high levels of wearing. Optionally, wherein the deflector shield is rigidly attached onto the primary frame; wherein the primary frame is the rigid connection between the wind vane and the deflector shield. Optionally, wherein the primary frame attaches onto a secondary frame such that the primary frame is rotatable around the secondary frame and the turbine; and wherein the secondary frame is stationary about the turbine, preferably wherein the secondary frame is circular and surrounds the turbine, further preferably wherein the centre of the secondary frame is concentric with the centre of the turbine. This arrangement may generalise the rotational motion of the primary frame around the turbine such that the primary frame follows a defined path (e.g. circular) within the secondary frame rather than pivoting from a single point around the turbine. Therefore, this combination of two frames may avoid issues related to the excessive wearing of a single pivoting point. This arrangement may also reduce probability of failure since the rotation is not dependant on a single point which may become damaged in extreme weather conditions. Optionally, wherein the primary frame is a circular frame; wherein the centre of the circular frame is concentric with the centre of the turbine. Advantageously, this circular shape follows the shape of the turbine as seen from above and may ensure even screening of all the turbine blades irrespective of resultant airflow direction. A circular profile may also ensure there is no localised area with increased wear on the circular frame due to the rotation of the wind vane and deflector shield. A circular profile may be needed when used in combination with a secondary frame such that the path defined by the secondary frame may be followed without uneven clashing / uneven wear of the two frames. Optionally, wherein the primary frame is an axle aligned with the central axis of the turbine. This may material costs by avoiding a frame entirely yet achieving the required pivoting component. Optionally, wherein the attachment of the wind vane and deflector shield onto the primary frame is at a position vertically above or vertically below the turbine. This may ensure that there are no additional barriers (regarding the attachment infrastructure) other than the deflector shield that may be present between the turbine and the resultant airflow direction. Additional barriers may introduce or increase the turbulent air incident upon the turbine blades or may screen turbine blades in the second portion of the turbine rotation path. This may increase noise or reduce the efficiency of the turbine. Optionally, wherein the wind vane and deflector shield are configured to rotate together in either a clockwise or anticlockwise direction around the turbine. This may allow the wind vane and deflector shield to respond to a resultant airflow from any direction around the turbine (without the aid of additional mechanisms to orientate the wind vane such that a specific face of the wind vane has airflow incident upon it from the resultant direction). Optionally, wherein the wind vane and deflector shield are configured to rotate in opposite directions; wherein the rotation of the wind vane in a first direction drives the movement of the deflector shield in a second direction. Optionally, wherein the deflector shield is configured to divert airflow away from the path of the turbine blades rotating towards the resultant force of the airflow; and wherein the deflector shield is configured such that at least a portion of the diverted airflow is guided towards the path of the turbine blades rotating with the direction of the resultant force of the airflow; wherein the diverted airflow superimposes with the incident airflow from the resultant force direction onto the turbine blades rotating in this direction. This arrangement may not only increase efficiency by reducing the resistive forces acting on the turbine but may also increase the total power produced by the turbine (for a given wind speed). It may achieve this by increasing the airflow incident upon the turbine blades rotating in the second portion of the turbine rotational path, i.e. the turbine blades rotating with the direction of the resultant airflow direction. Optionally, wherein the deflector shield comprises: a proximal end; and a distal end; wherein the proximal end is configured to be located into the direction of the resultant force of the airflow; wherein the distal end is configured to be located towards the turbine blades and in the direction of their rotation. This may allow for a means effectively to guide and divert the airflow towards the second portion of the turbine rotational path in a low complex arrangement. Optionally, wherein the geometry between the proximal and distal ends is curved so as to maintain the attachment of the airflow along the length of the deflector shield. Advantageously, an attached airflow may allow for greater manipulation and control of a larger quantity of airflow so that it can be diverted towards the second portion of the turbine. Optionally, wherein the deflector shield comprises a tail portion; wherein the tail portion attaches onto the proximal end of the deflector shield; wherein the tail portion extends towards the turbine blades that are rotating towards the resultant airflow direction. This may ensure that a sufficient width of the first portion of the turbine rotation path is screened and may prevent airflow from traveling around the proximal end of the deflector shield towards the turbine blades in this portion. Optionally, wherein the tail portion comprises a lip at its tip so as to divert airflow away from the turbine. Advantageously, this may also prevent airflow from travelling around the proximal end of the deflector shield. Optionally, wherein the wind vane comprises a greater surface area that projects perpendicularly to the turbine's rotational path than the deflector shield so as to produce a greater rotational force from the resultant force of the airflow than the deflector turbine. This may ensure that even with a deflector shield that projects into the direction of the resultant force it is the wind vane that will drive the deflector shield- and not the other way around. This would allow for the implementation of the benefits associated with the shaped and curved deflector shield without interference to the overall mechanism of the present invention. In accordance with a second aspect of invention there is disclosed a turbine for use atop a building, wherein the turbine comprises; a first turbine blade; a second turbine blade; and the shield of the first aspect; wherein both the first and second turbine blades rotate around the centre axis of the turbine in either a clockwise or anticlockwise direction. Wind turbines perform best with a strong and uninterrupted airflow. Such an airflow may be found at altitudes a few metres above ground level. Usually wind turbines are situated atop tall shaft structures to achieve this required height, however, utilising a roof of a building to do so may prevent the need to build such infrastructure. A roof is also easily accessible and the components listed above are easily implementable for settings atop buildings. Optionally, wherein the turbine blade comprises a proximal end adjacent the centre of the turbine; wherein the turbine blade extends radially outwards from the proximal end in a first direction; wherein the turbine blade is shaped such that it curves in a second direction. Advantageously, such curved blades may increase the efficiency of the turbines. Optionally, wherein the turbine blades are configured such that they curve along the length of the turbine blade as it extends from the proximal end to the distal end. Optionally, wherein the turbine blades are configured such that they curve from a single location on their length. Both the above two optional features may increase the efficiency of the turbine blades and do utilise manufacturing techniques commonly used in their industry. Optionally, wherein the turbine comprises three or more turbine blades rotating around its centre axis. This additional blade (s) may increase the efficiency and / or the power output of a turbine. Optionally, wherein a first turbine blade is configured to be positioned and rotate in a separate vertical plane to a second turbine blade. This may allow for many blades to be stacked vertically, such that more airflow may be incident upon the turbine blades at a given time, leading to an increased power output of the turbine. In accordance with a third aspect of invention there is disclosed a chimney for a building, wherein the chimney comprises; a chimney; the turbine of the second aspect; the shield of the first aspect; wherein the turbine and shield are configured to be accommodated at least partially within the chimney body. Advantageously, the chimney provides a desirable height that may be clear of / above turbulent airflow, therefore, utilising the chimney's existing infrastructure may prevent the need to build additional height gaining means. It may be a benefit in itself that the components of the shield described in the first aspect and the turbine of the second aspect are compatible with a chimney. Additionally this may provide a benefit by providing a less visual impact to the user as the chimney may appear the same or similar to similar structures employed for other means. In accordance with a fourth aspect of invention there is provided a method of use of a shield for deflecting airflow around a turbine, the method comprising the steps of: rotating a wind vane around a turbine under the resultant force of the airflow incident on it into a position around the turbine such that the wind vane is in equilibrium with the airflow forces incident on it; rotating a deflector shield into a position on the turbine such that it screens the turbine blades rotating against the direction of the resultant force of the airflow. Advantageously, the rotation of the wind vane and the deflector shield is a passive movement and therefore requires no additional energy input into the system that may detract from its efficiency. Additionally, the wind vane is configured to naturally orientate itself into a consistent orientation with respect to a resultant force direction (i.e. parallel with it) and therefore provides a convenient reference position to angularly size a deflector shield such that it screens the turbine blades rotating towards the resultant airflow direction. Optionally, wherein the method further comprises the weather vane and deflector shield rotating around a stationary frame. Advantageously, a frame may provide a favourable structural distinction between the turbine and the shield components such that that turbine is not loaded with their weight. A stationary frame may also allow for a more stable attachment between the frame and the turbine, which may result in the increased longevity of the primary frame due to less wear and tear that may be associated with an otherwise rotational relationship. Additionally, since the primary frame is also a load-bearing part, a stationary relationship may lower the probability of failure as compared to if it was a moving part. In this arrangement, the wind vane may only need to produce sufficient force to move itself and the deflector shield and not the primary frame, which may allow for a more responsive / sensitive deflector shield rotation. Optionally, wherein the method comprises the wind vane and deflector shield rotating around a turbine by virtue of a rotating frame; wherein the wind vane and the deflector shield are stationary with respect to the frame, optionally wherein the rotating frame rotates around a stationary frame. Advantageously, this arrangement may allow for a more constraint and damped rotation of the all components around the turbine as the force produced by the wind vane drives both the frame and deflector shield. This may reduce likelihood of failure especially under high wind speeds where overly sensitive rotating components may experience high levels of wearing. A combination of two frame may help to divert wearing of all rotating components such that there are no localised stress locations which may result in a weak spot. Optionally, wherein the method comprises; diverting airflow via the deflector shield towards and onto the turbine blades rotating with the direction of the resultant force. Advantageously, this may increase the power output of the turbine. In accordance with a fifth aspect of invention there is provided a method of manufacturing the shield of claims of the first aspect, comprising the steps of: cutting or forming a first sheet of material to form a weather vane; cutting or forming a second sheet of material to form a deflector shield. Advantageously, this may create the wind vane and deflector shield as set out above with the associated advantages, and the method may be simple and cost effective. Optionally, wherein the method further comprises attaching the first and second sheets to a circular frame. Brief Description of Figures Figure 1 is a first viewpoint of a first embodiment of a shield assembly atop a rooftop where the first viewpoint is from the resultant airflow direction. Figure 2 is a second viewpoint of the shield assembly of Figure 1 where the second viewpoint is side on to a resultant airflow direction. Figure 3 is a top view of the shield assembly of Figures 1 and 2 seen in isolation from the rooftop of Figures 1 and 2. Figure 4 is a top view of a second embodiment of a shield assembly seen in isolation from the rooftop of Figures 1 and 2. Figure 5 is a flowchart outlining the method of use of the shield of Figures 1 to 4. Figure 6 is a flowchart outlining a method of manufacture of the shield of Figures 1 to 4. Detailed Description Figure 1 shows a shield for deflecting airflow around a turbine comprising turbine blades, wherein the shield comprises: a deflector shield; and a wind vane; wherein the wind vane is configured to rotate around the turbine under the resultant force of the airflow incident on the wind vane; wherein the wind vane is configured to rotate with the resultant force into a first position; wherein the deflector shield is configured to be driven by the rotation of the wind vane and rotate around the turbine. Figure 1 is a view of the shield assembly 1 from the direction of the resultant airflow incident onto the shield. In Figure 1, the plane of the wind vane 3 is parallel with the resultant airflow direction and hence the area of its pane is hidden by the axle 5 to which the wind vane attaches onto. This position, whereby the plane of the wind vane is aligned with the resultant airflow direction is a position of stable equilibria for the wind vane as both the faces of its pane experience an equal and restoring force back to this airflow aligned position. The wind vane passively settles into this position for any resultant airflow direction with just the force of the airflow incident upon it driving it and does not require any external artificial forces being applied onto the wind vane. This orientation of the wind vane with respect to the resultant airflow direction will be referred to as the first position throughout this specification. Also seen in Figure 1 is that the deflector shield 7 is in a position such that it screens a portion of the turbine's width that is seen from the direction of the resultant airflow. A rotating turbine 9 has a rotational path whereby each blade travels both with the direction of the resultant airflow and against it for one complete rotation around the turbine. Therefore, the rotational path of the turbine can be differentiated, or portioned, based on these two conditions; a first portion where the blades travel against the resultant airflow and a second portion where the blades travel with the airflow direction. These two portions of the turbine rotational path are referenced throughout the specification. The deflector shield in Figure 1 is configured such that the portion of the width of the turbine that is screened from the resultant airflow direction is the first portion of the rotational path of the turbine i.e. the portion that comprises the turbine blades rotating against the resultant airflow direction. In Figure 1, this first portion is the right half of the turbine. In Figure 1, the portion of the turbine's width that is screened by the deflector shield 7 is approximately half that of the total turbine width that is seen from the resultant airflow direction. Other embodiments may screen a different portion of this width. The unscreened portion and the portion that is left exposed to the resultant airflow direction is the second portion of the rotational path of the turbine i.e. the portion that comprises the turbine blades rotating with the direction of the resultant airflow direction. Hence, via such arrangement, the turbine is still driven by the airflow that would otherwise drive it without the implementation of the shield 1 of the present invention. It is merely the resistive airflow, i.e. the airflow that is incident upon the turbine against its rotational direction, that the turbine is screened from. Advantageously, such an arrangement substantially reduces the drag on the turbine and in turn increases its efficiency and power output without interfering detrimentally with the airflow that drives the turbine which may cause a loss in power. It is important to note that the deflector shield 7 settles into the screening position seen in Figure 1 when the wind vane 3 settles into its first position. Although a schematic of the motion of the deflector shield 7 and the wind vane 3 around the turbine is not shown in Figure 1, it is understood that the rotation of the wind vane 3 drives the rotation of the deflector shield 7. In the current embodiment, there is no lost motion between the motion of the wind vane 3 and the deflector shield 7 as the two are rigidly connected via the rotating frame 11 (both attach onto the rotating frame 11)- this may not be the case in alternative embodiments. The rotating frame 11, or other forms of a rigid connection, ensures that the wind vane 3 and the deflector shield 7 are constrained at a constant angle throughout their rotation around the turbine. The angle at which they are constrained is naturally the angle required to achieve the desired abovementioned arrangement where the deflector shield 7 screens a first portion of the turbine's rotational path when the wind vane 3 is in a first position. The angular separation between the wind vane 3 and the deflector shield 7 is dependant on the turbine blade length (or the radius of the turbine's rotational path) and may require sizing accordingly prior to assembly. It is understood that the abovementioned first position of the wind vane 3 and the corresponding first portion screening position of the deflector shield 7 are terms defined with respect to the resultant airflow direction. Both the wind vane and the deflector shield 7 respond by virtue of rotating around the turbine to changes in the resultant airflow direction. As the direction of a resultant airflow onto a turbine changes, the spatial location of a wind vane 3 around the turbine also changes until the first position is achieved (the position where the plane of the wind vane 3 is parallel with the resultant airflow direction). Since the wind vane 3 drives the deflector shield 7, and since the first portion of the turbine is now different due to a change in the resultant airflow direction, the position of the deflector shield 7 also changes. It is this calibration with the resultant airflow direction that allows the shield 1 of the present invention to screen the desired portions of a turbine's rotational path irrespective of the direction of the resultant airflow direction incident upon it. The embodiment seen in Figure 1 is of a shield assembly with two frames, a rotating frame 11 and a fixed support frame (not seen in this view). The fixed support frame accommodates the turbine architecture, by virtue of providing structural and weight bearing support, and forms the structure around which the rotating frame 11 rotates. A bearing (not shown) may be used between the fixed support frame and the turbine axel as well as the fixed and rotating frames. The fixed support frame is stationary with respect to the turbine to aid in its function of structurally supporting it. The fixed support frame may comprise a flat bottom to provide a uniform and level platform upon which the turbine rotates. This may be particularly useful when atop sloping rooftops. The rotating frame 11 is the element both the wind vane 3 and the deflector shield 7 are attached onto in this embodiment. Other embodiments may comprise a mechanical linkage between the wind vane 3 and the deflector shield 7 that is not the rotating frame 11. This rotating frame 11 is configured to attach onto and rotate around fixed support frame. Both the fixed and rotating frames of the current embodiment are circular and have their centres concentric with one another and the axel of the turbine. This is better seen in Figures 3 and 4. The wind vane 3 and the deflector shield 7 are stationary with respect to the rotating frame 11 when the frame rotates around the turbine. Such an arrangement with the implementation of two frames may ensure a more controlled rotation around the turbine of the rotating frame 11 as the path of the rotating frame 11 may be defined, guided and supported by the shape and structure of the fixed frame. Since the deflector shield 7 may be subject to adverse weather conditions with high wind speeds, the combinations of the two frames may be more structurally robust as compared to a wind vane rotating around either a fixed frame or a single rotating frame rotating upon a single pivot. It is acknowledged that the frame architecture of the present invention may take various alternate forms to that described above. It may be that alternative embodiments may only utilise one frame, either a fixed frame upon which the wind vane 3 and the deflector shield 7 attach onto and rotate around the turbine themselves; or a rotating frame 11 alone that is not supported by a fixed frame. In the case of the single fixed frame, the rigid connection between the deflector shield 7 and wind vane 3 may have to be a separate feature to the body of the frame itself to allow the rotation around the turbine. In such embodiments, it may be that the deflector shield 7 only attaches onto the wind vane 3. Such a connection may provide greater convenience when assembling the shield. In the case of a single rotating frame, the architecture may resemble the architecture disclosed in Figures 1 to 4 and described above with the exception of the fixed support frame. For all the arrangements, it may be that the deflector shield 7 may attach onto the wind vane 3 directly, or via an additional element. It may also be that the wind vane 3 and deflector shield 7 may attach onto the frame and the frame may be the rigid connection between the deflector shield and the wind vane 3 for embodiments involving rotating frames. The alternative frame embodiments described above may be of non-circular structure and may instead be axles aligned with the central axis of the turbine. It may also be advantageous for aerodynamic purposes to have the bodies of the frames above, below or within the turbine so as to not introduce turbulent air into the path of the rotating blades of the turbine. Said turbulent air may introduce noise and lead to a loss in efficiency. Figure 1 shows the turbine 9 used in conjunction with the shield 1 as a vertical axis turbine positioned atop a rooftop 13. The turbine is also seen to be fixed atop the roof via fixing points / poles 15. Other embodiments may accommodate the turbine 9 and the shield assembly 1 within other existing roof architectures such as chimneys (not shown). More about the turbine 9 will be explored in the description of Figure 3. Also shown in Figure 1 is the fixing table 17, a permanent magnet generator 19 and support rods 21 for the turbine 9. Figure 2 shows the arrangement of a first embodiment of the shield 1 of Figure 1 from a second view and isolated from the roof architecture. This second view is perpendicular to the view of Figure 1 and shows the shield assembly 1 from side-on to a resultant airflow direction, whereby the airflow is incident upon the turbine from the right. The view of the turbine 9 seen in Figure 2 is almost entirely of the second portion of the rotational path where the turbine blades 9 are rotating with the direction of the resultant airflow. Figure 2 shows much of that described in Figure 1 and more clearly showcases the area of the second portion of the rotational path of the turbine 9 that is unscreened by the deflector shield 7. Also seen in Figure 2 is the deflector shield 7 being positioned some distance from the turbine blades 9 so as to avoid clashing with the rotating blades. Figure 2 also outlines the symmetry within the architecture of the shield assembly 1 when viewed from different angles from around the turbine 9. This symmetry ensures the turbine 9 is well prepared from resultant airflows from every direction as there is no physical barrier that may prevent airflow from any direction from being stopped from reaching the turbine blades of a second portion of the rotational path and the only barrier that may screen the turbine blades is the carefully positioned deflector shield 7. Figure 2 outlines a triangular shape of the wind vane 3 in this first embodiment, however, any other shape may be implemented. There may be an advantage in implementing wind vanes 3 of a larger surface area so as to more effectively capture the force from the resultant airflow direction. The size of the wind vane 3 may need to be sized with respect to the weight of the components that need to be rotated by the force produced by the wind vane 3. For example, in a rotating frame arrangement 11, the force produced by the wind vane would need to drive both the rotating frame 11 and the deflector shield 7, whereas in a fixed frame arrangement with only the wind vane 3 and deflector shield 7 being configured to rotate around the frame, the force may only need to drive the deflector shield 7. The wind vane 3 and deflector shield 7 of Figures 1 and 2 are configured to rotate around the turbine 9 in both a clockwise and anticlockwise direction dependant on the direction of the resultant airflow onto the wind vane 3. The wind vane 3 is configured such that it achieves the first position with respect to the resultant airflow direction via the simplest route around the turbine 9, this may be the clockwise or anticlockwise direction. Since the deflector shield is driven by the rotation of the wind vane 3, and there is no lost motion with the wind vane, it travels in the same direction as the wind vane. However, since Figures 1 and 2 are two-dimensional, it may appear from these viewpoints that a leftwards movement of the wind vane 3 results in a rightwards movement of the deflector shield 7. Other embodiments of the deflector shield shown in Figures 1 and 2 may utilise an arrangement where the deflector shield 7 and the wind vane 3 move in opposite directions to one another, i.e. a clockwise rotation of the wind vane 3 resulting in an anticlockwise rotation of the deflector shield 7. This may involve an alternative link to a rigid connection between the two components. This may also involve the implementation of gears or other means to achieve this relative motion. Figure 3 shows a top view of the shield assembly 1. It can be assumed that for the deflector shield 7 to be positioned as it is in Figure 3 that the resultant airflow direction is from the bottom of the Figure. In the embodiment shown in Figure 3, the angular distance at which the deflector shield 7 and the wind vane 3 are held at is such that the axis of the plane of the wind vane 3 (not shown in Figure 3 but would be aligned vertically with the resultant airflow direction as discussed above) and the axis of the centre of the deflector shield 7 are angularly separated. This angular relationship between the deflector shield 7 and the wind vane 3 achieves the offset required in the placement of the deflector shield 7 such that the deflector shield 7 is biased to one side of the turbine 9 and therefore predominantly screens only the first portion of the turbine's rotational path when the wind vane is in a first position. In the current embodiment, the leading edge of the deflector shield 7 is positioned in line with the axis of the wind vane (not shown) such that the angle between the plane of the wind vane 3 and a line connecting the leading edge of the deflector shield 7 with the centre of the turbine 9 is pi radians. In other embodiments, this angle may be changed and the leading edge of the deflector shield 7 may be positioned more towards the first portion of the turbine rotational path (to the right of Figure 3) with the plane of the wind vane ahead of it. Here, the leading edge of the deflector shield 7 is the edge of the deflector shield 7 adjacent the second portion of the turbine rotational path or the vertical edge facing the resultant airflow direction. In other embodiments, this angle may be changed such that the deflector shield 7 screens more of a second portion of the turbine's rotational path or less of this first portion. The amount of the turbine width screened by the deflector shield 7 when viewed from the resultant airflow direction may be dependent on the shape of the turbine blades 9, in particular their curved profiles. For turbine blades 9 with long curved tails extending rightwards from the centre line of the width, the deflector shield 7 may be sized a screen a small portion of the turbine width 9. In the current embodiment, the entire first portion is screened with the leading vertical edge of the deflector shield 7 located at the centre line of the turbine's width. The leading edge of the deflector shield 7 is the vertical edge adjacent the second portion of the rotational path of the turbine. Should the deflector shield 7 only screen the portion of the turbine width that is seen from the resultant direction and no more, a large portion of the turbine 9 may be left exposed to resistive forces. Therefore, also seen in Figure 3, is a tail portion (entirely optional) that may extend from the protruding portion of the deflector shield to screen more completely the first portion of the turbine rotational path as the airflow incident upon the turbine may arrive from a plurality of directions. The turbine 9 seen in Figure 3 comprises eight blades rotating around the centre axis of the turbine. Each blade of the turbine in this embodiment attaches onto an axle at the centre of the turbine and extends radially outwards. Each blade is also curved along its length. Other embodiments may have different numbers of blades of different shapes. For example, a blade with two straight portions at an angle to one another, whereby the blades curve from a single location. Alternatively, a blade may also comprise of a plurality of straight sections at angles to one another rather than a gradual curve. The blades in this embodiment rotate in a clockwise direction, as indicated by the curve in the anti-clockwise direction from the centre of the blade outwards. Other embodiments may rotate in an anti-clockwise direction with blades curving in the clockwise direction. The turbine blades 9 in the embodiments shown in Figures 1 to 3 are two sets of turbine blades that are offset from one another, other embodiments may be arranged such that each turbine blade is in a vertical plane of its own or have all the blades in one plane. Figure 4 shows a same view of the shield assembly 1 as seen in Figure 3 but with a second embodiment of a deflector shield 7a. The deflector shield 7a seen in Figure 4 is equipped with geometry that not only diverts airflow away from the turbine blades 9 rotating towards the resultant airflow direction but guides this diverted airflow towards the blades rotating with the direction of the resultant airflow. Through such a deflector shield 7a shape, not only are the resistive forces upon a turbine 9 negated (with the removable of the resistive airflow), but the diversion of said airflow onto the turbine blades 9 rotating with the resultant direction actively increases the driving airflow incident upon the turbine per unit of time. This super positioning of the forces from the diverted airflow and the airflow directly incident upon it may increase the power output of the turbine by virtue of increasing the airflow onto the turbine blades 9 rotating with the resultant direction. The shape of the deflector shield 7a seen in Figure 4 comprises a portion that extends towards and into the direction of the resultant airflow direction and an end portion that lies adjacent the turbine blades 9 of a second portion of the turbine rotational path. Between these two portions the geometry is curved, firstly to capture a sufficient volume of air that is to be diverted and secondly to maintain the attachment of the airflow along the length of the deflector shield 7a- much like an aerofoil would be curved. The shape of the deflector shield 7a may differ from that described thus far in other embodiments yet achieve the same function. The tail portion shown in Figure 4 comprises a lip 25 at its end (entirely optional) that is used to divert a portion of the airflow away from the turbine entirely. Although not shown, a wind vane 3 when used in conjunction with the deflector shield 7a of Figure 4 may need to be sized to a greater surface area to compensate for the additional air resistance that may be experienced by the deflector shield 7a due to its protruding shape. The rotation around the turbine of both components is dependent upon the surface area that projects perpendicularly to the turbine rotational path as it is this projecting surface area that experiences the air resistance that drives their rotation. It is favourable for the present invention to function as intended if the wind van 3 drives the rotation of the deflector shield 7a, therefore, it must produce a greater rotational force than the deflector shield 7a. Figure 5 shows a method 50 of use of a shield for deflecting airflow around a turbine, the method comprising the steps of: rotating a wind vane around a turbine under the resultant force of the airflow incident on it into a position around the turbine such that the wind vane is in equilibrium with the airflow forces incident on it 51; rotating a deflector shield into a position on the turbine such that it screens the turbine blades rotating against the direction of the resultant force of the airflow 52. In addition, for the embodiments shown in Figures 1 to 4, the method comprises the weather vane and deflector shield rotating around a turbine by virtue of a rotating frame to which they are attached rotating around a stationary frame. The wind vane and deflector shield in said arrangement being stationary with respect to the rotating frame. In other embodiments as mentioned above with only a single frame arrangement, that being a fixed, or stationary, frame, the method may alternatively comprise rotation of only the wind vane and deflector shield around said stationary frame. For embodiments with deflector shields resembling that of Figure 4, a further step may also include diverting airflow via the deflector shield towards and onto the turbine blades rotating with the direction of the resultant force. This will increase the airflow available to drive the turbine blades and may increase power output of the turbine. Figure 6 shows a method 60 of manufacturing the shield assembly discussed above. The first step of the method comprises cutting or forming a first sheet of material to form a weather vane 61. At its simplest form, a weather vane is a planar shape with a large surface area. Manufacturing such an instrument can easily be done from cutting the desired shaped from a larger sheet, preferably a metal sheet. A second step in the manufacturing method involves cutting or forming a second sheet of material to form a deflector shield 62. Likewise with the weather vane, a deflector shield is a largely planar instrument that can be manufactured from cutting a desired shape from a larger material. To better fit a turbine's circular rotational path, a deflector shield may be curved with the same curvature depending on the turbine blade length. For embodiments seen in Figures 1 to 4, the manufacturing method may optionally involve manufacturing a circular frame. This may be via extruding metal or cutting metal. Alternatively, similar manufacturing methods may apply to a frames that merely constitute an axel. Attaching the wind vane and the deflector shield to a circular, or other shape of frame, may comprise the final assembly step of the shield assembly 63. The above embodiments are to be understood as illustrative examples. Further embodiments are also envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims. In some examples, one or more memory elements can store data and / or program instructions used to implement the methods described herein. Embodiments of the disclosure provide tangible, non-transitory storage media comprising program instructions operable to program a processor to said method and / or claimed herein. 5 The processor / controller of such apparatus (and any of the methods, activities or instructions outlined herein) may be implemented with fixed logic such as assemblies of logic gates or programmable logic such as software and / or computer program instructions executed by a processor. Other kinds of programmable logic include programmable processors, programmable digital logic (e.g. a field programmable gate 10 array (FPGA), an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM), an application specific integrated circuit (ASIC) or any other kind of digital logic, software, code, electronic instructions, flash memory, optical disks, CD-ROMs, DVD ROMs, magnetic or optical cards, other types of machine-readable mediums suitable for storing electronic 15 instructions, or any suitable combination thereof. Such data storage media may also provide the data storage of the manufacturing device.

Claims

1. A shield for deflecting airflow around a turbine comprising turbine blades, wherein the shield comprises:a deflector shield; anda wind vane;wherein the wind vane is configured to rotate around the turbine under the resultant force of the airflow incident on the wind vane;wherein the wind vane is configured to rotate with the resultant force into a first position;wherein the deflector shield is configured to be driven by the rotation of the wind vane and rotate around the turbine;wherein the shield comprises a primary frame;wherein the primary frame is a circular frame;wherein the primary frame is configured such that the primary frame is rotatable around the turbine;wherein the wind vane rigidly attaches onto the primary frame such that it is stationary with respect to the primary frame;wherein the rotation of the wind vane drives the rotation of the primary frame about the axis of the turbine;wherein the primary frame attaches onto a secondary frame such that the primary frame is rotatable around the secondary frame and the turbine;wherein the secondary frame is stationary about the turbine, wherein the secondary frame is circular and surrounds the turbine.

2. The shield of any preceding claim, wherein when the wind vane is in the first position, the deflector shield is configured to be positioned such that it screens at least a portion of the turbine blades that are rotating against the direction of the resultant force of the airflow.

3. The shield of any preceding claim, wherein the rotational path of the turbine comprises a first portion and a second portion;wherein the turbine blades are configured to rotate against the direction of the resultant force of the airflow in the first portion;wherein the turbine blades are configured to rotate with the direction of the resultant force of the airflow in the second portion;wherein the deflector shield is configured to screen at least a section of thefirst portion when the wind vane is in the first position; and / or wherein the deflector shield is configured to be positionedsuch that a section of the second portion is exposed to the airflow from the resultant force direction when the wind vane is in the first position.

4. The shield of any preceding claim, wherein the first position is a position in which the plane of the wind vane is parallel with the direction of the resultant force of the airflow;wherein the wind vane is configured to settle into the first position;wherein the first position is a position of stable equilibrium for the wind vane.wherein the deflector shield is configured to settle when the wind vane is settled;wherein the position settled into by the deflector shield is a position of stable equilibrium for the deflector shield.

5. The shield of any preceding claim, when dependant on claim 3, wherein the shield comprises a rigid connection between the wind vane and the deflector shield;wherein the rigid connection is configured to constrain the angular distance between the deflector shield and the wind vane such that the angular distance is constant throughout the rotation of both the wind vane and deflector shield; and / orwherein the angular distance at which the deflector shield and wind vane are held at is such that in the first position of the wind vane, the deflector shield screens a section of the first portion of the turbine; and / orwherein the angular distance at which the deflector shield and the wind vane are held at is such that the axis of the plane of the wind vane and the axis of the centre of the deflector shield are angularly separated; and / orwherein the leading vertical edge of the deflector shield is configured to be positioned such that the plane of the wind vane intersects it or is ahead of it;wherein the leading edge is the edge of the deflector shield closest to or partially screening the second portion when viewed from the direction of the resultant force of the airflow; optionallywherein the angle between the plane of the wind vaneand a line connecting the centre of the turbine to the leading edge is pi radians.

6. The shield of any preceding claim, wherein the primary frame is stationary about the turbine, and the wind vane is configured to attach onto the primary frame and rotate around the primary frame; and / orwherein the deflector shield is configured to attach onto the primary frame such that the deflector shield is rotatable around it.

7. The shield of any preceding claim, wherein the deflector shield is rigidly attached onto the primary frame;wherein the primary frame is the rigid connection between the wind vane and the deflector shield.

8. The shield of any preceding claim, wherein the centre of the secondary frame is concentric with the centre of the turbine.

9. The shield of any preceding claim, wherein the centre of the circular frame is concentric with the centre of the turbine; orwherein the primary frame is an axle aligned with the central axis of the turbine.

10. The shield of any preceding claim, wherein the attachment of the wind vane and deflector shield onto the primary frame is at a position vertically above or vertically below the turbine.

11. The shield of any preceding claims, wherein the wind vane and deflector shield are configured to rotate together in either a clockwise or anticlockwise direction around the turbine.

12. The shield of claim 11, wherein the wind vane and deflector shield are configured to rotate in opposite directions;wherein the rotation of the wind vane ina first direction drives the movement of the deflector shield in a second direction.

13. The shield of any preceding claim, wherein the deflector shield is configured to divert airflow away from the path of the turbine blades rotating towards the resultant force of the airflow; andwherein the deflector shield is configured such that at least a portion of the diverted airflow is guided towards the path of the turbine blades rotating with the direction of the resultant force of the airflow;wherein the diverted airflow superimposes with the incident airflow from the resultant force direction onto the turbine blades rotating in this direction.

14. The shield of claim 13, wherein the deflector shield comprises:a proximal end; anda distal end;wherein the proximal end is configured to be located into the direction of the resultant force of the airflow;wherein the distal end is configured to be located towards the turbine blades and in the direction of their rotation; and / orwherein the geometry between the proximal and distal ends is curved so as to maintain the attachment of the airflow along the length of the deflector shield; and / orwherein the deflector shield comprises a tail portion;wherein the tail portion attaches onto the proximal end of the deflector shield;wherein the tail portion extends towards the turbine blades that are rotating towards the resultant airflow direction; and / orwherein the tail portion comprises a lip at its tip so as to divert airflow away from the turbine; and / orwherein the wind vane comprises a greatersurface area that projects perpendicularly to the turbine's rotational path than the deflector shield so as to produce a greater rotational force from the resultant force of the airflow than the deflector shield.

15. A turbine for use atop a building, wherein the turbine comprises;a first turbine blade;a second turbine blade; andthe shield of claims 1-14;wherein both the first and second turbine blades rotate around the centre axis of the turbine in either a clockwise or anticlockwise direction.

16. The turbine of claim 15, wherein the turbine blade comprises a proximal end adjacent the centre of the turbine;wherein the turbine blade extends radially outwards from the proximal end in a first direction;wherein the turbine blade is shaped such that it curves in a second direction.

17. The turbine of claim 16, wherein the turbine blades are configured such that they either:curve along the length of the turbine blade as it extends from the proximal end to the distal end; orcurve from a single location on their length.

18. The turbine of any claims 15 to 17, wherein the turbine comprises three or more turbine blades rotating around its centre axis; and / orwherein a first turbine blade is configured to be positioned and rotate in a separate vertical plane to a second turbine blade.

19. A chimney for a building, wherein the chimney comprises;a chimney;the turbine of claims 15 to 18;the shield of claims 1-14;wherein the turbine and shield are configured to be accommodated at least partially within the chimney body.

20. A method of use of a shield for deflecting airflow around a turbine, wherein the shield is the shield of claims 1-14, the method comprising the steps of:rotating a wind vane around a turbine under the resultant force of the airflow incident on it into a position around the turbine such that the wind vane is in equilibrium with the airflow forces incident on it;rotating a deflector shield into a position on the turbine such that it screens the turbine blades rotating against the direction of the resultant force of the airflow.

21. The method of claim 20, wherein the method either comprises:the weather vane and deflector shield rotating around a stationary frame; orthe wind vane and deflector shield rotating around a turbine by virtue of a rotating frame;wherein the wind vane and the deflector shield are stationary with respect to the rotating frame, optionallywherein the rotating frame rotates around a stationary frame.

22. The method of any claims 20 or 21, wherein the method comprises;diverting airflow via the deflector shield towards and onto the turbine blades rotating with the direction of the resultant force.

23. A method of manufacturing the shield of claims 1-14, comprising the steps of: cutting or forming a first sheet of material to form a weather vane;cutting or forming a second sheet of material to form a deflector shield.

24. The method of manufacturing of claim 23, wherein the method further comprises attaching the first and second sheets to a circular frame.

Images