IE20090973U1

IE20090973U1 - A wind turbine blade assembly

Info

Publication number: IE20090973U1
Application number: IE2009/0973A
Authority: IE
Inventors: Francis Goodfellow Joseph
Original assignee: C & F Tooling Limited
Filing date: 2009-12-23
Publication date: 2011-11-09

Abstract

ABSTRACT The present invention relates to a pitch control arrangement for wind turbine blade assembly. A wind turbine blade assembly (2) including a hub (7), at least one blade (8) pivotally mounted on the hub (2) for swivelling about a longitudinal axis of the blade (8), a blade swivel mechanism (10) housed within the hub (7) and operably connected to each blade (8) for swivelling the blade on the hub (7), and actuating means/rod (12) for operation of the blade swivel mechanism (10). Actuating rod (12) is used to push or pull a swivel guide (24) as to swivel the blades ( 8) by pivoting the link arm (26) within the hub 7. An electronic control system is provided for control of the blade pitch mechanism. .

Description

Field of Invention This invention relates to a wind turbine. blade assembly and in particular, to a blade pitches control arrangement for the blade assembly.

Background of Invention Wind turbines are devices which conveit the kinetic energy in wind into useful energy such as electricity. In many constructions, two or more turbine blades are supported on a hub of the turbine housing. A wind turbine generally comprises of a rotor hub having plurality of airfoil shaped blades, an alternator, and a supporting structure. The rotor hub of wind turbine generally comprises of two or more blades. For a wind turbine to produce usable energy, the blades should have optimum rpm (rotation per minute). In the high wind , 15 speed region, the wind turbine needs to be controlled to maintain the aerodynamic power produced by blades. Pitch control (of the blades) is one of the ways/means of adjusting or controlling aerodynamic power of wind turbine blade.

Some of the problems of the current wind turbine blade assembly are lack of mechanism by which the angle of the blades can be changed.

It is the objective of this invention to achieve rotor blade pitch system to control the position of the blades in the events like high wind speed, power grid loss, and malfunctioning of the turbine electrical system.

Statement of Invention According to the invention, there is provided a wind turbine blade assembly including: a hub; at least one blade pivotally mounted on the hub for swiveling about a longitudinal axis of the blade; a blade swivel mechanism housed within the hub and operably connected to each blade for swivelling the blade on the hub; and an actuating means for operation of the blade swivel mechanism.

In one embodiment of the invention, the blade swivel mechanism comprises a swivel guide which is movable through the hub, said swivel guide being connected to each blade by a drive connector which is operable in response to movement of the swivel guide through the hub to swivel the blade on the hub.

In another embodiment, the drive connector comprises a link arm connected between the blade and swivel guide such that movement of the swivel guide within the hub causes the link arm to pivot within the hub.

In another embodiment, an outer end of the link arm is ﬁxed to the blade and an inner end of the link arm pivotally and slidably engages the swivel guide.

In a preferred embodiment, a pin at the inner end of the link arm slidably and pivotally engages a complementary guide slot in the swivel guide.

In another embodiment, the actuating means comprises an actuating rod connected to the swivel guide and drive means for driving the rod for movement of the swivel guide‘ through the hub.

In another embodiment, the actuating rod is axially movable through the hub.

In another embodiment the actuating rod is mounted - within a propeller shaft extending from ‘the hub, the rod being axially movable within a central bore of the propeller shaft.

IEa9aa73 In a further embodiment, each blade is mounted on the hub such that a swivel axis of the blade is offset from a central rotational axis of the hub. in another embodiment, the hub comprises a two—part metal casting of -clam shell — construction.

Brief description of the drawings The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings, in which: Fig. 1 is an elevational view of a wind turbine incorporating a blade assembly of the invention; Fig. 2 is sectional elevational view of the wind turbine; Fig. 3 is an enlarged detail sectional view showing a blade swivel mechanisrn of the blade assembly; Fig. 4 is a partially exploded detail perspective view showing a hub of the blade assembly; and Fig.’ 5 is an enlarged detail sectional elevational view showing portion of actuating means for the blade assembly.

Detailed Description of the Invention Refening to the drawings, there is shown a wind turbine according to the invention indicated generally by the reference numeral 1. The wind turbine 1 incorporates a blade assembly indicated generally by the reference numeral 2 in accordance with the present invention. The wind turbine 1 has a chassis 4 on which an alternator S is mounted. The blade assembly 2 is operable to drive a rotor of the alternator S.

The blade assembly 2 has a hub 7. A number of blades 8 extend outwardly from the hub 7. In some of the drawings, only an inner root portion of each blade 8 is shown. In this case, three blades 8 are provided. Each blade 8 has a pivot shaft 9 at its inner end which is pivotally mounted on the hub 7 for swivelling about a longitudinal axis of the blade 8. A ' blade swivel mechanism 10 housed within the hub 7 is operably connected to each blade _8 for swivelling the blade 8 in the hub 7. An actuating rod 12 for operation of the blade swivel mechanism 10 extends outwardly from the hub 7 through the chassis 4 and is connected by a pivoting link arm 14 with an electric screw mechanism 15 for moving the rod 12 axially back and forth.

Referring in particular to Fig. 3 the hub 7 and blade swivel mechanism 10 is shown in more detail. The hub 7 essentially comprises a two—part metal casting of calm shell construction comprising an inner part 20 and an outer part 21. These two parts 20, 21 are bolted together. A generally cylindrical chamber 22 is provided within the hub 7. A swivel guide 24 is movable through the chamber 22. A link arm 26 has an outer end 27 ﬁxed to the shaft 9 of the blade 8. An inner end 28 of the link arm 26 has a pin 29 which slidably and pivotally engages a complimentary radial guide slot 30 -in the swivel guide 24. Each blade 8 is similarly connected to the swivel guide 24. Thus, it will be appreciated that movement of swivel guide 24 through the chamber 22 causes each of the levers 26 to rotate thus simultaneously swivelling the blades 8 to which they are attached on the hub 7.

Movement of the swivel guide’ 24 through the hub '7 is controlled by the actuating rod 12. An outer end 35 of the actuating rod 12 is attached to the swivel guide 24. The actuating rod 12 is mounted within a propeller shaft 37 which extends inwardly from the hub 7 and is connected via a coupling 38 with a drive shaft 39 of theealternator 5. This drive shaﬁ 39 ' .» carries the rotor of the alternator 5. Axial bores 40, 41 in the propeller shaft 37 and drive shaft 39 allow through-passage of the actuating rod 12. o9ss73 .a5_ Referring in particular to Figs. 2 and 5, the link arm 14 is pivotally connected by a pivot pin 44 on a mounting bracket 45 on the chassis 4. A lower end 46 of the link arm 14 pivotally and slidably engages an outer end 47 of the actuating rod 12. A pivot pin 49 pivotally connects an upper end 50 of t11e link arm 14 with the electric- screw 15 which is mounted on the chassis 4. The electric screw 15 is operable to pivot the link arm 14 to push and pull the actuating rod 12 for movement of the swivel guide 24 through the hub 7 in order to control the pitch of the blades 8.

It will be noted in particular from Fig. 4 that a swivel axis of each blade 8, that is a rotational axis of each shaft 9, is ,offset ﬁ‘om a central rotational axis of the hub 7.

An electronic control system is provided for control of the blade pitch mechanism.

The control system consists of a microprocessor with inputs and outputs. Various inputs such as turbine rpm, pitch position, slew position, vibration, temperature and wind direction may be provided. After analyzing the various inputs, the system determines the pitch and slew positions of the blades 8 to harvest the most wind without over-speeding. In the event of an error condition, the machine will come to a stop. A text display may be employed to indicate the various conditions of the turbine 1. The system is driven by 24 volt DC provided by an AC mains power supply. This is backed up by a battery to enable operation and safe shut—down in the event of a power supply failure.

The blade pitch is adjusted according to the rpm of the machine. In low wind conditions, the blades 8 are pitched back slightly to get a better rotation from the wind. Then once some speed has been attained, the blades 8 pitch fully forward to a predetermined position where they stay until rpm is approaching 220 rpm. At this point, the blades 8 begin to pitch back to show the rotation speed. If the speed is not reduced before 330 rpm an emergency shut down is actuated which engages a disc brake and pitches the blades 8 fully back.

In operation, the blades 8 are driven by wind to rotate the propeller shaft 37 and drive ' shaft 39 of the alternator 5 for generating power. The pitch of the blades 8 can be regulated as required by operation of the blade swivel mechanism l0.This causes the actuating rod 30 to push or pull the swivel guide 24 for movement of the swivel guide 24 through the hub 7 in order to swivel the blades 8 by pivoting the link arm 26 within the hub 7.

In the event of an electric failure a mechanically activated fail safe mechanism operates. This may for example comprise a gas spring which acts on the link arm 14 to return the blade pitch to a safe (feathered) position.

It will be appreciated that the blade swivel mechanism of the invention is relatively simple, which is advantageous from a reliability point of view and also from a manufacturing cost point of view. Also, all the moving parts are sealed and protected within the hub 7.

It will be appreciated that any suitable mechanism may be provided for moving the actuating rod 12.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail. V

Claims

1. A wind turbine blade assembly including: a hub; at least one blade pivotally mounted on the hub for swivelling about a longitudinal axis of the blade; a blade swivel mechanism housed within the hub and operably connected to each blade for swivelling the blade on the hub; and an actuating means for operation of the blade swivel mechanism.

2. A wind turbine blade assembly according to claim 1, wherein the blade swivel mechanism comprises a movable swivel guideconnected to each blade by a drive connector which is operable in response to movement of the swivel guide through the hub to swivel the blade on the hub.

3. A 3. A wind turbine blade assembly according to claim 2, wherein the drive connector comprises a link arm connected between the blade and swivel guide such that the movement of the swivel guide within the hub causes the link arm to pivot within the hub.

4. A wind turbine blade assembly according to claim 3, wherein the outer end of the link arm is ﬁxed to the blade and an inner end of the link arm pivotally and slidably engages theswivel guide.

5. A wind turbine blade assembly according to any preceding claim, wherein the actuating means comprises an actuating rod connected to the swivel guide and drive means for the rod for movement of the swivel guide through the hub._