WIND TURBINE

Abstract: A wind-powered turbine has vanes (2-5; 36-39) that are pivoted (13; 44) to radial arms (6; 41) of its rotor (1; 30, 31) and are turned by rods (14; 45) linking the vanes (2-5; 36-39) individually to a common pivot (16; 47) which is offset from the rotor-axis (8; 42) on a crank-arm (17; 48). The rods (14; 45) constrain their pivots (15; 46) with the vanes (2-5; 36-39), to follow a circular path (B) centred on their common pivot (16; 47) on the crank-arm (17; 48) so that vane-pitch varies cyclically with rotor-rotation. Angular adjustment of the crank-arm (17; 48) about the rotor-axis (8; 42) varies the angular phasing of the pitch cycle within each revolution such that for constant wind speed and direction (W), rotor-speed changes. Where the rotor-axis (8) is vertical, maximum output torque is maintained by turning the crank-arm (17) in response to change of wind-direction sensed by a sensor-vane (21), and the rods (14) include hydraulic rams (23) for varying rod-lengths in feathering the vanes (2-5) into edge-on alignment withe wind when an anemometer (26) senses high-wind conditions. Where the rotor-axis (42) is horizontal, two rotors (30, 31) are mounted at opposite ends of a boom (32) that is turned across the wind according to wind-direction sensed by a vane (62), and in high-wind conditions sensed by an anemometer (63) is turned into alignment with the wind.

Description: WIND TURBINE This invention relates to turbines. The invention is particularly concerned with turbines of the kind having a rotor with vanes that are individually pivoted to the rotor and are each turned to vary its pitch as the rotor rotates. Turbines of this kind are known for use in harnessing wind power and in this context are commonly referred to as x indmills', but are applicable also for harnessing flow in water or other fluids. According to the present invention there is provided a turbine having a rotor with vanes that are individually pivoted to the rotor, wherein means for turning each vane on its pivotal axis to vary the pitch of the vane cyclically with rotation of the rotor, is coupled to a coupling point on the vane spaced from that axis and is operative during rotation of the rotor to constrain the coupling point to follow a circular path having its centre offset from the rotational axis of the rotor. The vanes may be pivotally mounted on respective radial arms of the rotor, and said means may comprise a plurality of links which respectively intercouple the coupling points of the vanes with a common point that is offset from the rotational axis of the rotor and relative to which the rotor rotates. The links may comprise individual rods, and the said common point may be a point on a member that is angularly displaceable about the rotational axis of the rotor for varying the angular phasing about that axis of the cyclic pitch variation of each vane. The rotor may be carried by a rotatably- mounted shaft and said member may then be carried by a shaft that is coaxial with the rotor shaft. The rotational axis of the rotor may be substantially vertical or substantially horizontal, and there may be a plurality of said rotors mounted for rotation in substantially parallel planes. Two forms of windmill in accordance with the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an illustrative side elevation of the first windmill according to the invention; Figure 2 is a schematic representation in plan to reduced scale, of a rotor of the windmill of Figure 1; Figure 3 is an enlarged schematic plan view of a central portion of the rotor of the windmill of Figure 1, showing hydraulic rams and a control system for them which are omitted for clarity from Figure 2 ; Figure 4 is a schematic plan view of the rotor of the windmill of Figure 1 with its vanes fully feathered for withstanding dangerous high-wind conditions; Figure 5 is an illustrative side elevation of the second windmill according to the invention; Figure 6 is a schematic representation to reduced scale, of one of two rotors of the second windmill, as viewed on the line VI-VI of Figure 5; and Figure 7 is illustrative to enlarged scale, of detail of the second windmill viewed in the direction of the arrow VII of Figure 5. Referring to Figures 1 and 2 , the rotor 1 of the windmill comprises four vanes 2 to 5 that are carried respectively by four mutually-orthogonal arms 6 of equal length that extend horizontally from a vertical, hollow shaft 7. The shaft 7 is mounted for rotation about its longitudinal axis 8 within a tower 9 of a cabin 10, and is coupled within the cabin 10 to the rotor of an electrical generator 11. Electrical power output of the generator 11 is accordingly dependent on rotation of the rotor 1 about the axis 8 under wind pressure on the vanes 2 to 5. Each of the vanes 2 to 5 has a mounting-bracket 12 by which it is attached to its respective arm 6 through a pivot 13. The pivot 13 allows the angle of pitch of the individual vane 2 to 5 relative to its arm 6 to be varied during the course of rotation of the rotor 1. More particularly, the vanes 2 to 5 are regulated in pitch by control rods 14 that in each case are coupled at one end to the bracket 12 of the respective vane 2 to 5 by a pivot 15 spaced from the vane-pivot 13. The other ends of the rods 14 are brought together for individual pivotal attachment within a common pivot 16 on the outer end of a crank-arm 17 of a vertical shaft 18. The shaft 18 extends coaxially within the hollow shaft 7 from a gearbox 19 that is driven by a stepping-motor or servo unit 20 within the cabin 10. The unit 20 sets the angular orientation of the crank-arm 17 in azimuth about the axis 8 in dependence upon the direction of the wind as sensed from the orientation of a wind-deflected vane 21 by a unit 22 external to the cabin 10. The orientation of the crank-arm 17 relative to the wind direction determines the speed with which the rotor 1 is turned by the wind, and accordingly the efficiency with which wind power is converted by the windmill to electrical power output from the generator 11. In the latter regard, the coupling of the control rods 14 to the pivot 16 offset from the rotor-axis 8, is effective to cause the pitch of each vane 2 to 5 to vary cyclically throughout each revolution of the rotor 1, as the pivots 13 and 15 follow overlapping circular paths A and B centred on the axis 8 and the pivot 16 respectively (Figure 2) . More particularly, the pitch of each vane 2 to 5 relative to its arm 6 varies progressively, but not at a uniform rate, throughout one complete turn, for each revolution of the rotor 1. During each revolution of the rotor 1, each vane 2 to 5 follows a cyclic pattern of progressively-changing pitch which, if considered as starting from the condition (represented in Figure 2 by the vane 2) in which it faces at right angles to its arm 6, it turns 135 degrees relative to its arm 6 in each of the first and second quadrants, and 45 degrees in each of the third and fourth quadrants; the vane accordingly takes up the orientations corresponding to those of the vanes 3, 4, 5 and 2 in Figure 2 at the ends of the first, second, third and fourth quadrants respectively. This cyclic pattern of progressively-changing pitch is followed throughout each revolution of the rotor 1, by each vane 2 to 5, with the nominal start of the pattern (vane facing at right angles to its arm 6) located with an orientation, or angular phasing, in azimuth dependent on the angular setting of the crank-arm 17 about the axis 8. With the angular setting of the crank-arm 17 relative to the direction of the wind W shown in Figure 2, the nominal start of the pattern of progressively-changing pitch for each vane 2 to 5 is with the vane facing full square into the wind W. In the instant of time represented in Figure 2 , the vane 2 is at the nominal start of the pattern and exerts maximum torque to turn the rotor 1 in the direction of the arrow R, and the vane 4 is edge-on to the wind W so exerts substantially no counteracting torque on the rotor 1. The vanes 3 and 5, furthermore, are correspondingly angled at 45 degrees to the wind W so that the substantially equal-torques of opposite sense they exert on the rotor 1 effectively cancel one another out. The result, therefore, is that the full effect of the wind pressure on the vane 2 is utilised to turn the rotor 1 in the direction R under maximum torque. As the rotor 1 turns, the angle of incidence of the wind W on each vane 2 to 5 changes, but, by virtue of the action of the rods 14 , so does the pitch of each vane 2 to 5 in a manner to maintain the same maximum magnitude and sense of torque on the rotor 1. In this regard, the contribution of torque from the vane 2 decreases progressively through the first 90 degrees of rotor- rotation from the position shown in Figure 2, and the vane 4 exerts an increasing counter-torque, but the torque exerted by the vane 5 in the direction R increases and the counteracting torque exerted by the vane 3 decreases. By the end of this quadrant of rotor- rotation, the vanes 2, 3, 4 and 5 occupy the positions, and have the pitch attitudes, of the vanes 3, 4, 5 and 2 respectively, of Figure 2. A corresponding sequence of progressively-changing positions and pitch of the vanes 2 to 5 with attendant increase and decrease of torque components, follows during the next three quadrants of rotor-rotation. The effect is to maintain the torque exerted on the rotor 1 by the wind W at the maximum. Change of direction of the wind W is detected by the unit 22 through the response of the vane 21, and causes the unit 20 to adjust the angle of the shaft 18, and therefore of the crank-arm 17 in azimuth, to maintain maximum torque. The adjustment of the angle of the crank-arm 17 has the effect of tilting the vanes 2 to 5 in pitch consistent with the change this adjustment makes in the angular phasing about the axis 8 at which they will each in turn again face full-square into the wind. If adjustment of the setting of the crank-arm 17 were not made when wind-direction changes, the torque exerted on the rotor 1 would be reduced from the maximum and the windmill would accordingly run at a slower speed. Clearly, if irrespective of change of wind direction, a change of running speed is desired, this can be readily achieved by adjusting the angular setting of the crank- arm 17. The adjustment can be made by means of manual or automatic control of the unit 20, and where automatic control is involved, this may be readily arranged to hold the speed, or the output of the generator 11, at a selected value. Provision is made for protecting the windmill against damage in gales and other dangerous high-wind conditions. In this respect, as illustrated in Figures 1 and 3 (but, for clarity, not in Figure 2) , hydraulic rams 23 are incorporated into the control rods 14. Each ram 23 is coupled into its rod 14 at the pivot 16 with its cylinder 24 attached to the crank-arm 17 through the pivot 16, and its piston 25 connected to the pivot 15. In normal circumstances, the piston 25 is locked within the cylinder 24 so that the overall length of the rod 14 remains fixed and equal to that of each other rod 14. However, when high-wind conditions are indicated, more particularly by the wind-speed sensed by an anemometer 26, the unit 22 responds to this to activate an hydraulic-control unit 27. The unit 27 is connected by pairs of hydraulic lines 28 and 29 (only one pair shown in full) to opposite ends of the cylinders 24, and when activated unlocks the pistons 25 and operates the rams 23 to adjust the lengths of the rods 14. The lengths of the rods 14 are adjusted, as illustrated in Figure 4, in accordance with the wind-direction as sensed by the vane 21, to tilt all the vanes 2 to 5 edge-on to the wind W, fully feathered. Once the danger has passed, the fall in sensed wind-speed causes the hydraulic unit 27 to return the pistons 25 to their normal positions within the cylinders 24 and lock them there. The principles of the vertical-axis windmill described above are applicable to the provision of a horizontal- axis version as illustrated in Figures 5 and 6 and will now be described. Referring to Figures 5 and 6, two rotors 30 and 31 are in this case located at opposite ends of a horizontal boom 32 that is rotatable on a bearing 33 at the top of a tower 34 of a cabin 35. Each rotor 30 and 31 comprises four vanes 36 to 39 that are carried on a hollow shaft 40 by respective mutually-orthogonal arms 41 of equal length, for rotation in a vertical plane about the horizontal axis 42 of the shaft 40. The vanes 36 to 39 of each rotor 30 and 31 have mounting- brackets 43 that are attached to the rotor-arms 41 by pivots 44. Regulation of the pitch of each vane 36 to 39 about its pivot 44 is effected in each case by an individual control rod 45 that at its outer end is attached to the bracket 43 of that respective vane through a pivot 46. The inner ends of the control rods 45 are attached individually through a common pivot 47 to the outer end of a crank-arm 48 of a shaft 49 which extends coaxially within the shaft 40. The co-linear shafts 40 of the rotors 30 and 31 are coupled via respective bevel gears 50 to a bevel gear 51 of a vertical hollow shaft 52 within the tower 34, whereas (as illustrated more clearly in Figure 7) the shafts 49 are coupled via respective bevel gears 53 to a bevel gear 54 of a shaft 55. The shaft 52 is coupled at its lower end within the cabin 35 to the rotor of an electrical generator 56, and the shaft 55 extends through this from a gearbox 57 that is driven by a stepping-motor or servo unit 58. Manual or automatic control of the unit 58 is effective to vary via the gearbox 57 and the shaft 55, and thence via the shafts 49, the corresponding angular settings of the crank-arms 48 of the rotors 30 and 31, and accordingly the angular phasing within each revolution of the rotors 30 and 31 at which the vanes 36 to 39 face horizontally in turn. The optimum phasing (for maximum torque) is that in which the vanes 36 to 39 of the rotor face horizontally either at the bottom or the top of the revolution; the rotors 30 and 31 are illustrated with this phasing in Figures 5 and 6, the horizontally-facing vane condition being at the bottom for the rotor 30 and at the top for the rotor 31 to afford balance. If with this setting of the crank-arms 48, the boom 32 is turned across the wind (the condition illustrated in Figure 6) , maximum torque will be exerted by both rotors 30 and 31 to obtain maximum speed of rotation of the shaft 52 and output from the generator 56. The speed can be reduced, simply by adjusting the angular settings of the crank- arms 48 through the unit 58. The boom 32 is maintained turned across the wind by means of an electric motor 59 that drives it in azimuth on the bearing 33, via gearing 60. The motor 59 is in this respect controlled from a unit 61 that responds to the orientation of a wind-deflected vane 62 mounted externally of the cabin 35. The unit 61 is also responsive to dangerous high-wind conditions indicated by an anemometer 63, to activate the motor 59 to turn the boom 32 into alignment with the wind so that the vanes 36 to 39 are then all edge-on to the wind direction for safety. Although in both examples described above the rotors each have four vanes, they may have fewer or more. Furthermore, solar panels (such as indicated in chain- dotted outline SP on the panels 36 in Figure 5) may be attached to the vanes so that electrical power is available irrespective of whether the wind is blowing. The principle of the pitch-angle adjusting mechanism used in the windmills described above may be applied to the comparable adjustment of vanes of a water-current driven turbine. More especially, the rotors of the windmills described above may be utilised underwater to derive power from water current.

Claims: Claims : 1. A turbine having a rotor with vanes that are individually pivoted to the rotor, wherein means for turning each vane on its pivotal axis to vary the pitch of the vane cyclically with rotation of the rotor, is coupled to a coupling point on the vane spaced from that axis and is operative during rotation of the rotor to constrain the coupling point to follow a circular path having its centre offset from the rotational axis of the rotor. 2. A turbine according to Claim 1 wherein the vanes are pivotally mounted on respective radial arms of the rotor. 3. A turbine according to Claim 1 or Claim 2 wherein said means comprises a plurality of links which respectively intercouple the coupling points of the vanes with a common point that is offset from the rotational axis of the rotor and relative to which the rotor rotates . 4. A turbine according to Claim 3 wherein the links comprise individual rods. 5. A turbine according to Claim 3 or Claim 4 wherein said common point is a point on a member that is angularly displaceable about the rotational axis of the rotor for varying the angular phasing about that axis of the cyclic pitch variation of each vane. 6. A turbine according to Claim 5 wherein the rotor is carried by a rotatably-mounted shaft and said member is carried by a shaft that is coaxial with the rotor shaft. 7. A turbine according to Claim 5 or Claim 6 including means for sensing the flow-direction relative to the rotational axis of the rotor of driving fluid incident on the vanes, and means for adjusting the angular displacement of said member about the rotational axis of the rotor in dependence upon the sensed flow-direction. 8. A turbine according to any one of Claims 3 to 7 wherein the links include means for selectively varying their relative lengths from the condition in which they are all of substantially the same length as one another, for feathering the vanes. 9. A turbine according to Claim 8 including means for sensing the flow-rate of driving fluid incident on the vanes, and means for varying the relative lengths of the links as aforesaid in dependence upon the sensed flow- rate. 10. A turbine according to any one Claims 1 to 9 wherein the rotational axis of the rotor is substantially vertical. 11. A turbine according to any one Claims 1 to 6 wherein the rotational axis of the rotor is substantially horizontal. 12. A turbine according to any one of Claims 1 to 6 comprising a plurality of said rotors mounted for rotation in substantially parallel planes. 13. A turbine according to Claim 12 wherein the planes of rotation of the rotors are substantially vertical. 14. A turbine according to Claim 13 comprising two said rotors mounted at opposite ends of a boom with their axes of rotor-rotation co-linear. 15. A turbine according to Claim 14 wherein the boom is mounted for angular displacement about a substantially vertical axis for varying the orientation of the rotors in azimuth. 16. A turbine according to Claim 15 including means for sensing the flow-direction in azimuth of driving fluid incident on the vanes, and means for adjusting the angular displacement of the boom about the substantially vertical axis in dependence upon the sensed flow- direction. 17. A turbine according to Claim 16 including means for sensing the flow-rate of the driving fluid incident on the vanes, and wherein said means for adjusting the angular displacement of the boom is operative to turn the rotational axes of the rotors into substantial alignment with the sensed flow-direction in dependence upon the sensed flow-rate. 18. A turbine according to any one of Claims 1 to 17 operable as a windmill.

Inventors: ROGAN ALAN JOHN, ROGAN, ALAN, JOHN
Applicants: ROGAN ALAN JOHN, ROGAN, ALAN, JOHN
Application year: 2001
Main classification: F03D3
IPC codes: F03D3