Windmill
First Claim
1. A variable pitch turbine blade system, comprising:
- a blade, including a radially inner fixed end and a radially outer free end, said blade being continuously torsionally flexible between said free end and a radially inner point on said blade, said radially inner point being intermediate of said fixed end and said free end; and
an out-of-plane weight means, attached to said blade, for continuously varying a pitch of said blade in response to a variation in rotational speed of said turbine blade system, said pitch being continuously varied between a maximum variation adjacent said weight means and a smaller variation at said radially inner point for a given variation of said rotational speed of said turbine blade system;
wherein said weight means includes a mass with a center of mass thereof leading an elastic axis of said blade so that said turbine blade system operates free from flutter, and with said center of mass located out of a plane of rotation of said elastic axis of said blade so that a component of a centrifugal force acting on said mass acts to twist said blade about said elastic axis to vary the pitch of said blade.
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Accused Products
Abstract
This invention relates generally to an improved windmill design that combines the blade and rotor support system with the electrical generating system in such a way as to simplify the windmill construction. Specifically, it eliminates the need for shafts, gears, and other coupling devices between the turbine blade system and the electrical generating system. In addition, the windmill design also includes a means for varying the pitch of the turbine blades automatically so as to provide near-optimum blade angles under varying wind conditions, and a tendency toward self-governing at high wind speeds. Furthermore, the blades are attached rigidly to the hub without the need for bearings or other mechanical couplings. Blade pitch changes are produced by twisting the blades elastically by forces produced by fixed weights. The effect of these features individually and in combination is to reduce the complexity of the wind turbine, the generating system, and their associated parts.
154 Citations
31 Claims
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1. A variable pitch turbine blade system, comprising:
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a blade, including a radially inner fixed end and a radially outer free end, said blade being continuously torsionally flexible between said free end and a radially inner point on said blade, said radially inner point being intermediate of said fixed end and said free end; and an out-of-plane weight means, attached to said blade, for continuously varying a pitch of said blade in response to a variation in rotational speed of said turbine blade system, said pitch being continuously varied between a maximum variation adjacent said weight means and a smaller variation at said radially inner point for a given variation of said rotational speed of said turbine blade system; wherein said weight means includes a mass with a center of mass thereof leading an elastic axis of said blade so that said turbine blade system operates free from flutter, and with said center of mass located out of a plane of rotation of said elastic axis of said blade so that a component of a centrifugal force acting on said mass acts to twist said blade about said elastic axis to vary the pitch of said blade. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A variable pitch turbine blade system, comprising:
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a blade, including a radially inner fixed end and a radially outer free end, said blade being continuously torsionally flexible between said fixed end and said free end; and an out-of-plane weight means, attached to said blade, for continuously varying a pitch of said blade in response to a variation in rotational speed of said turbine blade system, said pitch being continuously varied between a zero pitch variation at said fixed end and a maximum pitch variation adjacent said weight means for a given variation of said rotational speed of said turbine blade system; wherein said weight means includes a mass with center of mass thereof leading an elastic axis of said blade so that said turbine blade system operates free from flutter, and with said center of mass located out of a plane of rotation of said elastic axis of said blade so that a component of a centrifugal force acting on said mass acts to twist said blade about said elastic axis to vary the pitch of said blade. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A windmill, comprising:
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a shaft; a turbine blade system; first and second permanent magnet alternators, each of said alternators including a multiple pole stator fixedly mounted on said shaft and a multiple magnet permanent magnet structure rotatably mounted coaxial with said stator, said turbine blade system being connected to said magnet structures to rotate therewith, the poles of said stator of said second alternator being angularly offset from the poles of said first alternator and wherein the magnets of said magnet structures of said first and second alternators are aligned in axial rows so that only one of said first and second alternators can have the poles of its stator radially aligned with the magnets of its magnet structure at any given time. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A windwill, comprising:
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a turbine blade system; first and second electrical generating means, each of said generating means including a fixedly mounted multiple pole stator and including a multiple pole rotor rotatably mounted coaxial with said stator, said turbine blade system being connected to said rotors to rotate therewith, said first and second electrical generating means being arranged so that at any given time only one of said first and second electrical generating means can have its stator poles and its rotor poles so relatively positioned as to present a maximum cogging force for said one generating means, so that at any given time a total cogging force presented by said first and second electrical generating means is less than a total of a maximum cogging force of said first generating means plus a maximum cogging force of said second generating means. - View Dependent Claims (25, 26, 27, 28)
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29. A windmill, comprising:
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a shaft; a turbine blade system; first and second permanent magnet alternators, each of said alternators including a multiple pole stator fixedly mounted on said shaft and a multiple magnet permanent magnet structure rotatably mounted coaxial with said stator, said turbine blade system being connected to said magnet structures to rotate therewith, the poles of said stator of said second alternator being angularly offset from the poles of said first alternator; wherein said turbine blade system includes; a central hub, attached to said magnet structures; a torsionally flexible blade having a radially inner end, fixedly attached to said hub, and a radially outer free end; and an out-of-plane weight attached to a radially outer location on said blade, so that the pitch of said blade is continuously decreased, with increasing rotational velocity of said turbine blade system, until a portion of said blade is stalled causing the turbine blade system to be self-governing at approximately the rotational velocity at which said stall occurs. - View Dependent Claims (30, 31)
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Specification