Extendable wind turbine blade

Patent metadata

Field	Value
Publication number	US-11885293-B2
Application number	US-202217717676-A
Country	US
Kind code	B2
Filing date	Apr 11, 2022
Priority date	Apr 12, 2021
Publication date	Jan 30, 2024
Grant date	Jan 30, 2024

Abstract

An extendable wind turbine blade for being extended in length during operation thereof, the wind turbine blade having an exterior surface with a root region and an airfoil region and comprising a first blade segment including a first portion of the exterior surface, a second blade segment including a second portion of the exterior surface, and a connection mechanism connecting the blade segments, and being configured to bring the wind turbine blade to a retracted state, in which the portions of the exterior surface are flush and adjoining, when the wind turbine blade operates above a threshold rotational speed and to bring the wind turbine blade to an extended state, in which the portions of the exterior surface are disconnected and the blade length is at least 101% of the blade length in the retracted state, when the wind turbine blade operates below the threshold rotational speed.

First claim

The invention claimed is:

1. An extendable wind turbine blade, comprising:
a root end and a tip end, the wind turbine blade extendable along a longitudinal axis running between the root end and the tip end;
an exterior surface with a root region and an airfoil region;
a leading edge and a trailing edge, and a chord line extending between the leading edge and trailing edge;
a first blade segment including a first portion of the exterior surface and a first end;
a second blade segment including a second portion of the exterior surface and a second end, the second blade segment being separate from the first blade segment, the first end and the second end being opposite and facing each other;
a connection device engaged between the first blade segment and the second blade segment, the connection device having a first length when the second blade segment is in a retracted state when the wind turbine blade operates above a threshold;
the connection device having a second length when the second blade segment is in an extended state when the wind turbine blade operates below the threshold;
wherein, in the retracted state, the wind turbine blade has a first length from the root end to tip end and the first portion of the exterior surface is arranged flush with and adjoining the second portion of the exterior surface;
wherein, in the extended state, the wind turbine blade has a second length from the root end to tip end and the second blade segment is arranged with a gap to the first blade segment so that the first portion of the exterior surface and the second portion of the exterior surface are disconnected;
wherein the second length is greater than the first length; and
the connection device configured to allow a centrifugal force generated at a cut-in speed of the wind turbine blade to move the second blade segment away from the first blade segment thereby bringing the wind turbine blade to the extended state.

2. The wind turbine blade according to claim 1 , wherein the connection device is configured to rotate the second blade segment relative to the first blade segment when bringing the wind turbine blade between the retracted and extended states so that, in the retracted state, the second blade segment is oriented at a first pitch angle and, in the extended state, the second blade segment is oriented at a second pitch angle, wherein a difference between the first and second pitch angles is in the range of 1° to 45°.

3. The wind turbine blade according to claim 2 , wherein the connection device comprises:
a female section;
a male section slidably received by the female section, wherein the female section is attached to either the first or second blade segment and the male section is attached to the other one of the first or second blade segment; and
the male section slidably engaging the female section via a threading with a pitch configured to orient the second blade segment at the first pitch angle in the retracted state and to orient the second blade segment at the second pitch angle in the extended state.

4. An extendable wind turbine blade, comprising:
a root end and a tip end, the wind turbine blade extendable along a longitudinal axis running between the root end and the tip end;
an exterior surface with a root region and an airfoil region;
a leading edge and a trailing edge, and a chord line extending between the leading edge and trailing edge;
a first blade segment including a first portion of the exterior surface and a first end;
a second blade segment including a second portion of the exterior surface and a second end, the second blade segment being separate from the first blade segment, the first end and the second end being opposite and facing each other;
a connection device engaged between the first blade segment and the second blade segment, the connection device having a first length when the second blade segment is in a retracted state when the wind turbine blade operates above a threshold;
the connection device having a second length when the second blade segment is in an extended state when the wind turbine blade operates below the threshold;
wherein, in the retracted state, the wind turbine blade has a first length from the root end to tip end and the first portion of the exterior surface is arranged flush with and adjoining the second portion of the exterior surface;
wherein, in the extended state, the wind turbine blade has a second length from the root end to tip end and the second blade segment is arranged with a gap to the first blade segment so that the first portion of the exterior surface and the second portion of the exterior surface are disconnected;
wherein the second length is greater than the first length; and
wherein the connection device comprise a biasing element configured to apply a biasing force that urges the second blade segment away from the first blade segment so that the wind turbine blade is biased towards the extended state.

5. The wind turbine blade according to claim 4 , wherein the threshold is based on one or more of: a rotational speed threshold, a power threshold, a wind speed threshold, a load threshold, a noise threshold, and a force or acceleration threshold.

6. A wind turbine blade according to claim 4 , wherein the biasing element is configured so that the biasing force of the biasing element overcomes a retracting gravitational force urging the second blade segment towards the first section during a top part of a revolution of the wind turbine blade during operation.

7. The wind turbine blade according to claim 4 , wherein the connection device comprises an actuator configured to apply an actuation force in a default state and a release state, wherein in the default state the actuator applies an actuation force that urges the second blade segment towards the first blade segment to bring the wind turbine blade to the retracted state.

8. The wind turbine blade according to claim 7 , wherein in the release state, the actuator is configured to reduce the actuation force so that the biasing force from the biasing element overcomes the actuation force to bring the wind turbine blade to the extended state.

9. The wind turbine blade according to claim 4 , wherein the connection device is configured to rotate the second blade segment relative to the first blade segment when bringing the wind turbine blade between the retracted and extended states so that, in the retracted state, the second blade segment is oriented at a first pitch angle and, in the extended state, the second blade segment is oriented at a second pitch angle, wherein a difference between the first and second pitch angles is in the range of 1° to 45°.

10. The wind turbine blade according to claim 9 , wherein the connection device comprises:
a female section;
a male section slidably received by the female section, wherein the female section is attached to either the first or second blade segment and the male section is attached to the other one of the first or second blade segment; and
the male section slidably engaging the female section via a threading with a pitch configured to orient the second blade segment at the first pitch angle in the retracted state and to orient the second blade segment at the second pitch angle in the extended state.

11. An extendable wind turbine blade, comprising:
a root end and a tip end, the wind turbine blade extendable along a longitudinal axis running between the root end and the tip end;
an exterior surface with a root region and an airfoil region;
a leading edge and a trailing edge, and a chord line extending between the leading edge and trailing edge;
a first blade segment including a first portion of the exterior sur

Assignees

• Lm Wind Power As

Inventors

• Korsgaard John
• Cnossen Jelmer

Classifications

• F03D1/0633 Primary

  of the blades · CPC title

• F03D1/0675 Primary

  of the blades · CPC title

• F05B2240/302

  Segmented or sectional blades · CPC title

• F03D7/0236 Primary

  by changing the active surface of the wind engaging parts, e.g. reefing or furling · CPC title

• F03D7/0256

  Stall control (adjusting the blades in stall position F03D7/0224) · CPC title