Wind powered system for generating electricity
First Claim
1. A wind turbine system for generating electricity, comprising:
- a wind turbine rotor;
a rotor shaft connected to said hub for rotation with said wind turbine rotor;
a step-up transmission having a low speed input connected to said rotor shaft and a high speed output;
a rotary pole amplitude modulated induction machine having a rotor that is connected to the output of said transmission, said machine being operable as a generator at a plurality of discreet speeds of rotation;
wind speed responsive switch means for changing speed of operation of said induction machine; and
wherein said wind turbine rotor comprises an elongated central hub with no twist having rounded edges and a substantially constant thickness between the edges;
a pair of fixed pitch essentially straight blades, each blade extending radially outwardly from said hub in a direction diametrically opposite from the other blade;
each said blade having a mid-section of airfoil cross section positioned radially outwardly of said central hub portion, and a tip section of airfoil cross section positioned radially outwardly of the mid-section;
each said blade smoothly changing from the substantially constant thickness and rounded edge shape of the central hub portion into an airfoil cross section as it extends radially outwardly from the central hub portion;
each blade first changing to first a plus twist and then a zero twist and then a minus twist as it extends radially outwardly;
each said blade tapering in thickness and chord as it extends radially outwardly from a location in its mid-section through its tip section; and
wherein the tip section of each said blade includes a sculptured tip end portion which decreases in thickness as it extends radially outwardly , said tip portion having an aerodynamic cross-sectional shape which progressively decreases in size, and having a leading edge which progressively sweeps rearwardly.
1 Assignment
0 Petitions
Accused Products
Abstract
A fixed pitch wind turbine rotor (18) is teeter mounted (76, 78, 80) onto a low speed input shaft (44) which is connected to the input (58) of a step-up transmission (46). The output (48) of the transmission (46) is connected to a rotary pole amplitude modulated induction machine (42) which is operable as a generator at a plurality of discreet speeds of rotation and is also operable as a startup motor for the rotor. A switch (45) responsive to the rotational speed of the wind turbine rotor switches the generator from one speed of operation to the other. The rotor hub (72) and the inner body portions (71) of two blades (68, 70), which extend radially outwardly in opposite directions from the hub (72), are constructed from steel. The outer end portions (73) of the blade (68, 70) are constructed from a lighter material, such as wood, and are both thinner and narrower than the remainder of the rotor. The outer end section (73) of each blade (68, 70) includes a main body portion and a trailing edge portion (104) which is hinge-connected to the main body portion. Each blade (68, 70) includes a centrifugal force operated positioning means (98, 100) which normally holds the drag brake section (104) in a retracted position, but operates in response to a predetermined magnitude of centrifugal force to move the drag brake (104) section into its deployed position. Each blade has an airfoil cross section and each blade (68, 70) has a plus twist inner portion adjacent the hub (72) changing to first a zero twist and then a minus twist as it extends radially outwardly from the hub (72).
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Citations
18 Claims
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1. A wind turbine system for generating electricity, comprising:
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a wind turbine rotor; a rotor shaft connected to said hub for rotation with said wind turbine rotor; a step-up transmission having a low speed input connected to said rotor shaft and a high speed output; a rotary pole amplitude modulated induction machine having a rotor that is connected to the output of said transmission, said machine being operable as a generator at a plurality of discreet speeds of rotation; wind speed responsive switch means for changing speed of operation of said induction machine; and wherein said wind turbine rotor comprises an elongated central hub with no twist having rounded edges and a substantially constant thickness between the edges; a pair of fixed pitch essentially straight blades, each blade extending radially outwardly from said hub in a direction diametrically opposite from the other blade; each said blade having a mid-section of airfoil cross section positioned radially outwardly of said central hub portion, and a tip section of airfoil cross section positioned radially outwardly of the mid-section; each said blade smoothly changing from the substantially constant thickness and rounded edge shape of the central hub portion into an airfoil cross section as it extends radially outwardly from the central hub portion; each blade first changing to first a plus twist and then a zero twist and then a minus twist as it extends radially outwardly; each said blade tapering in thickness and chord as it extends radially outwardly from a location in its mid-section through its tip section; and wherein the tip section of each said blade includes a sculptured tip end portion which decreases in thickness as it extends radially outwardly , said tip portion having an aerodynamic cross-sectional shape which progressively decreases in size, and having a leading edge which progressively sweeps rearwardly. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A wind powered system for generating electricity, comprising:
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a support tower; a nacelle on top of the support tower; a step-up transmission within said nacelle having a low speed end and a high speed end; a rotary electric generator within said nacelle having a rotor with an input end which is connected to the high speed end of the transmission, said generator including means enabling it to operate as a generator at a plurality of discreet speeds of rotation; an input shaft having an inboard end connected with the low speed end of the transmission, and an outboard end; a wind turbine rotor comprising a hub and fixed pitch blades extending radially outwardly from said hub, said hub including means connecting it to the outboard end of said input shaft; each said blade having a fixed pitch mid-section of airfoil cross section and a fixed pitch outer end section of airfoil cross section; at least one outer end section including a main portion including a leading edge for said section, and a drag brake forming, trailing edge portion which is hinge-connected to said main portion, for movement between a retracted position in which it forms a streamline trailing edge for said outer end section and a deployed position in which it extends generally across the chord of the outer end section and functions as an aerodynamic drag brake; a centrifugal force triggered positioning means normally holding the drag brake in its retracted position, but operating in response to the development of a centrifugal force of than a predetermined magnitude to move said drag brake into its deployed position; and a releasable lock member having a lock position in which it locks the weight means in its inner position, and a centrifugal force operated trigger means for moving said lock member into an unlocked position in response to a centrifugal force of a predetermined magnitude, with said weight means being free to move radially outwardly from its inner position to its outer position, in response to centrifugal force, when the lock member is in its unlocked position. - View Dependent Claims (12, 13, 14)
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15. A wind powered system for generating electricity, comprising:
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a support tower; a nacelle on top of the support tower; a step-up transmission within said nacelle having a low speed end and a high speed end; a rotary electric generator within said nacelle having a rotor with an input end which is connected to the high speed end of the transmission, said generator including means enabling it to operate as a generator at a plurality of discreet speeds of rotation; an input shaft having an inboard end connected with the low speed end of the transmission, and an outboard end; a wind turbine rotor comprising a hub and fixed pitch blades extending radially outwardly from said hub, said hub including means connecting it to the outboard end of said input shaft; each said blade having a fixed pitch mid-section of airfoil cross section and a fixed pitch outer end section of airfoil cross section; at least one outer end section including a main portion including a leading edge for said section, and a drag brake forming, trailing edge portion which is hinge-connected to said main portion, for movement between a retracted position in which it forms a streamline trailing edge for said outer end section and a deployed position in which it extends generally across the chord of the outer end section and functions as an aerodynamic drag brake; a centrifugal force triggered positioning means normally holding the drag brake in its retracted position, but operating in response to the development of a centrifugal force of than a predetermined magnitude to move said drag brake into its deployed position; said positioning means for the drag brake comprising weight means mounted in the wind turbine rotor for radial translation between an inner position and an outer position, and linkage means interconnected between the weight means and the drag brake, said linkage means holding the drag brake in its retracted position when the weight means is in its inner position, and said linkage means holding the drag brake in its deployed position when the weight means is in its outward position; spring means for normally biasing the weight means radially inwardly, said spring means functioning to move the weight means from its outer position into its inner position when centrifugal force acting on said weight means drops below said predetermined magnitude; and a lock member for holding the weight means in its outer position, in opposition to the force of the spring means, and means for unlocking said lock member when the centrifugal force on the trigger mechanism drops below a predetermined magnitude, to free the weight means for inward movement. - View Dependent Claims (16, 17, 18)
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Specification