Wind turbine rotor control system

Claim 2

A constant speed wind turbine of the type comprising a tower-mounted free yawing carriage having vane means for aligning said carriage with the wind, a drive shaft defining a substantially horizontal rotor axis mounted for rotation in said carriage, and a wind-powered electrical generator operatively coupled to one end of said drive shaft having electrical terminals adapted to be connected to an electrical power grid, wherein the improvement comprises a rotor with variable pitch blades drivingly coupled coaxially to the other end of said drive shaft, and mechanical control means connected between said rotor and said carriage for establishing the pitch angle of said rotor blades collectively as a direct predetermined function of the blade pitch moment.

Claim 3

The wind turbine of claim 1, wherein said mechanical control means includes a rotating connecting element coaxially rotatably mounted on said drive shaft, drive link means for synchronously rotating said connecting element with respect to the rotation of said rotor about the rotor axis, pitch link means for establishing the pitch angle of said rotor blades collectively in accordance with the axial position of said connecting element along the rotor axis, and means for varying the axial location of said connecting element as a function of the rotor blade pitch forces transmitted thereto via said pitch link means.

Claim 4

The wind turbine of claim 2, wherein said location varying means includes a coaxial slider axially slidably mounted on said carriage, coaxial bearing means for rotatably mounting said connecting element to said slider at a predetermined fixed axial position with respect to said slider, and elastic linkage means connected between said slider and said carriage for applying a predetermined variable axial force to said slider in opposition to said blade pitch moment.

Claim 5

The wind turbine of claim 3, wherein said elastic linkage means includes a spring-loaded cam means for establishing a predetermined relationship between pitch angle and pitch moment from a minimum to a maximum pitch angle, inclusive.

Claim 6

The wind turbine of claim 3, wherein the improvement further comprises shutdown means for releasing the tension in said elastic linkage means to a minimum level for full feathering of said rotor blades.

Claim 7

The wind turbine of claim 5, further comprising manual means for operating said shutdown means.

Claim 8

The wind turbine of claim 5, further including vibration sensor means operatively connected to said carriage for producing an output signal in response to a predetermined large amplitude vibration threshold indicative of an unstable rotor condition, said shutdown means including means responsive to said vibration sensor means output signal for releasing the tension in said elastic linkage means.

Claim 9

The wind turbine of claim 3, wherein the improvement further comprises means for latching said elastic linkage means in a run condition and electronic means for releasing said latch means in response to a shutdown command, and vibration sensor means for producing a shutdown command in response to vibration above a predetermined amplitude.

Claim 10

The wind turbine of claim 8, wherein the improvement further comprises means operatively connected with said electrical generator for producing a shutdown command in response to disconnection from the electrical power grid.

Claim 11

The wind turbine of claim 1, wherein said rotor is a downwind rotor.

Claim 12

The wind turbine of claim 10, wherein said rotor includes a rotor teeter hub assembly with an inner teeter shaft member fixed to said drive shaft for rotation therewith having pair of aligned opposite radial arms defining a coaxial teeter axis, an outer teeter hub resiliently pivotally mounted on said radial arms for teetering on said teeter axis carrying a pair of spaced parallel blade mounting hinges extending in opposite directions in a plane substantially normal to said drive shaft and defining respective pitch axes transverse to teeter axis and displaced therefrom, and said rotor blades having inboard blade roots pivotally connected to said blade mounting members.

Claim 13

A downwind horizontal axis two bladed wind turbine of the type comprising a free yawing carriage having vane means for aligning said carriage with the wind, a drive shaft defining a substantially horizontal rotor axis mounted for rotation in said carriage and a wind-driven electrical generator operatively coupled to one end of said drive shaft, wherein the improvement comprises a downwind rotor assembly including a rotor teeter hub assembly with an inner teeter shaft member affixed to said drive shaft for rotation therewith and having a pair of aligned opposite radial arms defining a teeter axis, an outer teeter hub resiliently privotally mounted on said radial arms for limited teetering action on said teeter axis and carrying a pair of space parallel blade mounting hinges extending in opposite directions defining parallel pitch axes transverse to and displaced from said teeter axis in a plane nominally normal to drive shaft, a pair of rotor blades having inboard blade roots connected respectively to said blade mounting hinges, and elastic control means for establishing the pitch angle of said rotor blades as a function of the blade pitch moment.

Claim 14

A downwind horizontal axis two bladed wind turbine of the type comprising a free yawing carriage having vane means for aligning said carriage with the wind, a drive shaft defining a substantially horizontal rotor axis mounted for rotation in said carriage and a wind-driven electrical generator operatively coupled to one end of said drive shaft, wherein the improvement comprises a downwind rotor assembly including a rotor teeter hub assembly with an inner teeter shaft member affixed to said drive shaft for rotation therewith and having a pair of aligned opposite radial arms defining a teeter axis, an outer teeter hub resiliently privotally mounted on said radial arms for limited teetering action on said teeter axis and carrying a pair of space parallel blade mounting hinges extending in opposite directions defining parallel pitch axes transverse to and displaced from said teeter axis in a plane nominally normal to drive shaft, a pair of rotor blades having inboard blade roots connected respectively to said blade mounting hinges, and elastic control means for establishing the pitch angle of said rotor blades as a function of the blade pitch moment.

Claim 15

The wind turbine of claim 12, wherein said control means includes means connected between said rotor and said carriage for establishing the pitch angle of said rotor blades collectively as a direct predetermined function of the blade pitch moment.

Claim 16

The wind turbine of claim 13, wherein said control means includes a rotating connecting element coaxially rotatably mounted on said drive shaft, drive link means connected between said outer teeter hub and said connecting element for synchronously rotating said connecting element with respect to the rotation of said rotor assembly about the rotor axis, pitch link means connected between said connecting element and an identical point on each blade root displaced radially from the pitch axis for establishing the pitch angle of said rotor blades collectively in accordance with the axial position of said connecting element along the rotor axis, and means for varying the axial location of said connecting element as a function of the rotor blade pitch forces transmitted thereto via said pitch link means.

Claim 17

The wind turbine of claim 14, wherein said location varying means includes a coaxial slider axially slidably mounted on said carriage, coaxial bearing means for rotatably mounting said connecting element to said slider at a predetermined fixed axial position with respect to said slider, and elastic linkage means having run the shutdown positions connected between said slider and said carriage for applying predetermined variable force thereto in opposition to said blade pitch moment.

Claim 18

The wind turbine of claim 15, wherein the improvement further comprises said elastic linkage means being responsive to a shutdown command for selecting the shutdown condition in which tension on said slider is released to the minimum level, and electronic means responsive to an emergency condition for producing said shutdown command, whereupon said rotor blades are fully feathered for emergency protection.