GB2504552A

GB2504552A - Wind turbine with folding blades

Info

Publication number: GB2504552A
Application number: GB1213911.9A
Authority: GB
Inventors: Richard Alan Sturt
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-08-03
Filing date: 2012-08-03
Publication date: 2014-02-05
Also published as: GB201213911D0

Abstract

A horizontal wind turbine with a tower supporting at least one blade, which is arranged to rotate about an axis, where one or more blades is moveable from a first position 1a adapted for low wind speed to a second position 2a in which the wind force exerted on the blades is reduced, allowing the turbine to operate at higher wind speeds. Preferably one or more blades is pivotable from a standard operating position perpendicular to the wind direction to a position parallel to the wind direction, allowing the turbine to continue to operate with a higher wind speed with the remaining blades. The blades may be mounted on supporting bearings with some blades being mounted in front of the bearings and some behind. A method of operating a wind turbine is also claimed.

Description

Title: Wind Turbine for use in a wide range of wind speeds

Description

This invention is designed to allow horizontal wind turbines to operate through a larger wind speed range than conventional horizontal wind turbines where the blades are fixed approximately perpendicular to the direction of the wind. It is difficult to make conventional horizontal wind turbines operate effectively through a very wide range of wind speeds. Although the pitch of the blades can be altered to reduce the force exerted on the blades as the wind speed increases, this may not be sufficient to allow the wind turbine to operate at very high wind speeds.

This invention provides means for accommodating a bigger range of operating wind speeds in a horizontal wind turbine by varying the effective number of blades that are used at different wind speeds. For example the wind turbine may have two or more blades in its low wind configuration, while in the high wind configuration one or more of the blades may be folded away approximately parallel to the axis of the rotation of the turbine, As an example a horizontal wind turbine could have six blades in a low wind speed configuration which could reduce to three blades in a high wind configuration. In the high wind speed configuration three blades are folded away approximately parallel to the main axis of rotation of the turbine. The folded blades would present minimum frontal area to the wind and allow the turbine to continue to operate with the three remaining blades at a higher wind speed. It is not essential for the folded blades to pivot about theft connection with the rotational axis. As an alternative the blades may be folded about a pivot point between the root of the blade and its tip.

Figure 1 shows the side view of a six bladed turbine in the low wind speed configuration with all six blades in the normal positions approximately perpendicular to the direction of the wind.

Figure 2 shows rear the view of a six bladed turbine in the low wind speed configuration with all six blades in the normal positions approximately perpendicular to the direction of the wind.

Figures 3 shows the side view of a six bladed turbine in the high wind speed configuration with three of the blades in the normal position approximately perpendicular to the wind la and three blades folded away approximately parallel to the axis of rotation of the tirbine 2a.

Figures 4 shows the rear view of a six bladed turbine in the high wind speed configuration with three of the blades in the normal position approximately perpendicular to the wind Ia and three blades folded away approximately parallel to the axis of rotation of the turbine 2a, To give further flexibility the fixed blades and folding blades could be designed with different specification, for example different lengths and/or capable of withstanding different wind speeds. This would allow large lighter construction blades to be used as folding blades and smaller blades capable of withstanding a higher wind speed to be used as non-folding blades.

Figure 5 shows a turbine with three shorter blades for high wind speeds lb and three longer blades 2b for use in low wind speeds The blades of the wind turbine can be placed in front of or behind the supporting structure. The turbine blades may not be equally spaced when viewed along the axis of rotation of the turbine in order to maxinise the efficiency of the combination of blades in front of and behind the supporting structure.

Figure 6 shows a configuration with three non folding blades Ic in front of the supporting tower and three longer folding blades 2c behind the supporting tower.

Figure 7 shows a turbine with three shorter blades for high wind speeds ld and three longer blades 2d for use in low wind speeds with un-equal spacing around the axis of rotation on the turbine A method of moving the blades between the low wind speed and high wind speed positions either manually or preferably automatically is provided.

Figure 8 shows one possible method of moving the blades. Each blade is pivoted on a hinge 3 and connected to a worm gear arrangement 4 to provide the necessary turning torque. The worm gear is driven by an electro mechanical actuator 5. This mechanism is used to move the blade from the low wind open position 9a to the high wind closed position 9b. An electrical connection to transmit the power to the actuator is made using slip rings 8 connecting the rotating shaft and blade mounting 6 to the nacelle 7.

For clarity only one blade is shown in figure 8.

Claims

Claims 1. A horizontal wind turbine having a tower supporting one or more blades arranged to rotate about an axis in response to wind impinging on said blades, at least one of said blades being movable from a first position adapted for low wind speed operation to a second position in which the wind force exerted on the blades is reduced, thus permitting the turbine to operate at higher wind speeds.
2. A turbine according to claim 1 wherein the movable blade is pivotable between a first position in which it is oriented approximately perpendicularly to the wind direction and a second position wherein it is generally aligned with the axis of rotation whereby the wind force exerted on the movable blade is reduced.
3. A turbine as claimed in claim 2 wherein part only of the movable blade is pivotable from said first position to said second position.
4. A wind turbine where one or more blades fold away from the normal operating position to a position approximately parallel to the axis of rotation substantially reducing the force on the folded blade, thereby allowing the turbine to continue to operate with a higher wind speed with the remaining blade or blades.
5. A turbine according to any one of the preceding claims, which has two or more different blade designs which are optimised to be used at different wind speeds.
6. A turbine according to any one of the preceding claims wherein the blades are mounted on supporting bearings, some blades being mounted in front of the supporting bearings and some behind in order to simplify the mechanism to allow some of the blades to fold.
7. A turbine according to any one of the preceding claims, wherein the blades are not equally spaced when viewed along the axis of rotation of the turbine in order to optimise the aerodynamic efficiency of the configuration.
8. A method of operating a wind turbine over a wide range of wind speeds which comprises moving one or more blades from a first position in which they are subject to maximum force from the wind to a second position in which part or all of the movable blades ar subject to a reduced wind force whereby the energy transmitted to the turbine is less.