WO2009056702A2

WO2009056702A2 - Improvement to an oscillating propeller for a two-blade aerogenerator

Info

Publication number: WO2009056702A2
Application number: PCT/FR2008/001184
Authority: WO
Inventors: Marc Vergnet
Original assignee: Vergnet S.A.
Priority date: 2007-08-10
Filing date: 2008-08-08
Publication date: 2009-05-07
Also published as: FR2919902B1; FR2919902A1; WO2009056702A3

Abstract

The invention relates to an oscillating propeller (1) of a two-blade (10, 11) aerogenerator, said blades being symmetrically mounted in relation to the centre of a hub (12) of a rotor. The aerogenerator is fixed at the top of a supporting mast and the bottom of the mast is anchored to the ground. The hub (12) is mounted in such a way that it rotates with the driving axle (ω) of the aerogenerator and is fixed to the driving axle (ω) in an articulated manner by means of an articulation element (123) in order to drive an electric generator. The articulation element (123) of the articulation axle (Δ) perpendicular to the driving axle (ω) forms an angle (δ) with the normal (N) to the axis (γ) of the blades (10, 11). Intercalated elements are provided between the articulation element (123) and the hub (12) in circular openings (125) formed on the lateral surface of the hub (12) according to the articulation axle (Δ).

Description

Improvement of an oscillating propeller for a two-bladed aerator.

The present invention relates to the field of renewable energies, and proposes in particular an improvement of an oscillating propeller for a two-bladed aerator.

The problem causing the invention, but which should not limit the scope of the present application, relates to three-blade wind turbines consisting of a rotor rigidly mounted on a drive shaft which allows to drive an electric generator via a multiplier or not, the rotor for converting the kinetic energy of the wind into mechanical or electrical energy. In such wind turbines, the advantage is that the rotor is aerodynamically and mechanically balanced. But the fact that the rotor is mounted rigidly on the drive axis of the wind turbines causes strong stresses and increased fatigue since the dissymmetry of the aerodynamic forces acting on the disk swept by the three blades produces effects of torsions on the rotor, on the axis of drive of the wind turbines and on all the nacelle of these wind turbines tri blades.

In order to reduce the weight and costs of wind power plants, the three-bladed wind turbines are replaced by two-bladed winders. But when the rotor of two-bladed wind turbines is mounted rigidly on the drive axis of these two-bladed wind turbines, the aerodynamic stresses are even more accentuated.

The current solutions propose two-blade wind turbines with the advantage of reducing the weight and the costs of the wind turbine installations and which consist of a rotor mounted in an articulated way on the axis of drive of the wind turbines so as to drive the axis of drive by a hinge pin. This axis of articulation is perpendicular to the drive axis and perpendicular to the axis of the blades. This system is also called "oscillating hub" and reduces the aerodynamic stresses present on the two-blade wind turbines of the prior art about 30%. But the rotor joints made by bearings are sensitive to the stresses on the rotor and show signs of early wear. Moreover, the oscillation movements of the rotor hub lead to very strong stresses abutting the drive axis of the wind turbines.

JP 61 17 5277 proposes to prevent the contact wear between a hub and a fork caused by the oscillation of a rotor by providing a two-segment fork on the peripheral portion of a rotary shaft mounted on the top a guy and mount it to attach the rotor hub with shock-absorbing material.

WO 96, 20343 proposes an aerogenerator equipped with hydraulic cylinders which are controlled to allow the blades to move at desired angles of conicity.

And US 4,522,561 proposes a yaw damper to resist the rotation of the main assembly of an aeratorator about a vertical axis. But the damping is achieved by a shearing action imposed on the oil by the rotation of disks relative to a central disk.

But these damping devices are heavy and expensive and do not allow to achieve a high quality damping. Of course, to overcome such drawbacks, hydraulic stops have been imagined and the bearings have been gradually replaced by elastic joints made of laminated rubber / metal elements that allow to resume oscillating movements of the hub of the rotor. The object of the invention is therefore to improve the "oscillating hub" system of a two-bladed wind turbine so as to reduce the amplitude of oscillation of the propeller constituted by the rotor and the blades and the forces on the devices. return or braking of the oscillation of the propeller.

To achieve this purpose, a propeller of a two-blade type aerogenerator mounted symmetrically with respect to the center of a hub of a rotor, the two-bladed aerator being erected at the so-called upper end of a mast. support and the so-called bottom end of the support mast anchored to the ground characterized in that the hub is mounted integral in rotation with a drive shaft (ω) of the wind turbine and articulated via a hinge member to the drive axis (ω) of the wind turbine to drive an electrical generator implanted in a nacelle, the hinge axis articulation element (Δ) perpendicular to the drive axis (ω) of the aerogenerator forms an angle (δ) with the normal (N) to the axis (γ) of the blades to allow an oscillation movement of the helix along the axis of articulation (Δ), the intermediate elements are provided between the hinge member and the hub in circularly shaped orifices formed on the lateral surface of the hub along the axis of articulation (Δ) of the hinge member;

the hinge member being substantially cylindrical in shape or the hinge assembly constituting an assembly substantially forming a cylinder;

the intermediate elements being made of elastomer and reinforced by rigid lamellae of metal or textile or composite to allow the rotation of the articulation element in the hub of the rotor ensuring the oscillation of the helix, these intermediate elements deforming according to the oscillation movement of the propeller to reduce the mechanical stresses exerted on the structure of the wind turbine; and

the oscillating propeller comprising resilient devices provided to exert an elastic restoring force on all or part of the propeller oscillation movement.

According to another particular feature, the helix comprises elastic devices designed to exert an elastic restoring force on all the movement or a part of the oscillation movement of the helix, the elastic devices being springs or elastomer pads. According to another feature, the propeller comprises damping devices provided for braking all the movement or a part of the oscillating movement of the articulation element, the damping devices being of hydraulic or viscoelastic type. According to another feature, at least two hydraulic stops are fixedly mounted on the hub of the rotor and symmetrically with respect to the drive axis (ω) for braking the oscillation movement of the propeller.

According to another feature, the angle (δ) is substantially between 40 and 85 ° relative to the normal (N) to the axis (γ) of the blades and makes it possible to correct the angle of attack of the blades relative to in the wind.

Another object is achieved by proposing an operation of an oscillating propeller of an aerogenerator comprising a hinge element making it possible to transmit the driving torque of a hub of the propeller to a drive shaft (ω) of the aerogenerator for driving an electric generator implanted in a nacelle, characterized in that the propeller can oscillate along the axis of articulation (Δ) between so-called extreme angular positions, these extreme angular positions being determined as soon as a hydraulic stop fixedly mounted on the hub of the rotor is in contact with the drive shaft of the wind turbine and the propeller oscillation movement to reduce the aerodynamic stresses on the wind turbine is ensured by the rotation along the axis articulation (Δ) of the articulation element.

According to another feature, the propeller can oscillate "freely" on a part of its oscillation movement between the two extremal angular positions as long as the amplitude of oscillation is lower than this free oscillation movement.

According to another particularity, beyond the "free" oscillation movement, that is to say for an excessive oscillation movement of the propeller, a damping device of the hydraulic type is used in order to dampen this movement. excessive oscillation. The invention will be better understood and other objects, characteristics, details and advantages thereof will appear more clearly in the following explanatory description given with reference to the appended figures given as non-limiting examples in which: FIG. 1 represents a diagram of the oscillating helix according to the invention;

FIG. 2 illustrates the oscillation movement of the oscillating helix according to the invention: FIG. 2a shows the helix according to the invention in its original position, FIG. 2b represents the helix according to the invention in FIG. an oscillation position and FIG. 2c shows the helix in an abutment position;

FIG. 3 illustrates the angle of attack of the blades with respect to the wind: FIG. 3a represents the angle of attack of the blades with respect to the wind when the oscillating propeller is in its original position and FIG. representing the angle of attack of the blades with respect to the wind for the oscillating propeller in oscillation position, the comparison between Figures 3a and 3b illustrating the variation of the angle of attack of the blades with respect to the wind; and

- Figure 4 shows a front view of the hub of the rotor in the direction of the hinge axis of the hinge element. The present invention aims to improve an oscillating propeller (1) of a two-bladed aerator so as to reduce the dynamic and kinematic stresses on the two-bladed aerator. Referring to Figure 1, the invention relates to a propeller (1) oscillating a wind turbine type two blades (10, 11) mounted symmetrically with respect to the center of a hub (12) of a rotor. The hub (12) of the rotor is mounted to rotate with a drive shaft (ω) of the wind turbine and articulated to the drive shaft (ω) of the wind turbine via a hinge member (123). The articulation hinge element (123) perpendicular to the drive axis (ω) of the wind turbine forms an angle (δ) with the normal (N) to the axis ( γ) blades (10, 11). In this way, the hinge element, or the assembly of the joints constituting a set, (123) of form substantially cylindrical thus allows the transmission of the engine torque from the hub (12) of the propeller (1) to the drive shaft (ω) of the wind turbine so that the drive shaft (ω) drives an electric generator implanted in a nacelle via a multiplier (2) or not to convert this wind energy into electrical or mechanical energy. The nacelle is rotatably mounted at a so-called upper end of a guyed or unmounted support mast, so that the blades (10, 11) are positioned in front of the nacelle. The so-called lower end of the support mast is anchored to the ground and, in the case of a guyed support mast, the support mast is held vertically by the stays anchored to the ground at one end and connected to the support mast by a second end. It should be noted that the elevation of the aerogenerator on the support mast is effected by means of a known lifting system.

In addition to the transmission of the engine torque from the hub (12) to the drive shaft (ω), the hinge element (123) allows the propeller (1) to oscillate or pivot according to the hinge pin (Δ) of the hinge member (123). Indeed, the rotation of the hinge element (123) along the axis of articulation (Δ) causes an oscillation or pivoting movement for the helix (1) along the axis of articulation (Δ). . This oscillation or pivoting movement of the propeller (1) allows it to adapt to the heterogeneity of the wind and to reduce the bending generated by the propeller (1) on the drive shaft (ω) of the wind turbine.

With reference to FIG. 4a, intermediate elements (124) are provided between the articulation element (123) and the hub (12) in orifices (125) of circular shape and of diameter greater than the diameter of the element. hinge. These orifices (125) are formed on the lateral surface of the hub (12) along the axis of articulation (Δ) of the articulation element (123). These intermediate elements (124) inserted into the orifices (125) are made of elastomer and are reinforced by rigid lamellae of metal or textile or composite, thus offering a high compressive strength and flexibility in shear sufficient to allow the rotation of the element articulation (123) in the hub (12) of the rotor ensuring the pivoting or oscillation of the helix (1) along the axis of articulation (Δ). During this oscillation or pivoting movement of the propeller (1), these intermediate elements (124) can deform, as shown in Figure 4b, so as to reduce the mechanical stresses exerted on the wind turbine. In addition, these intermediate elements (124) have the advantage of a long service life and exemption from any maintenance.

The oscillating propeller (1) comprises elastic devices such as springs or elastomeric pads so as to exert a resilient restoring force on all or part of the oscillation movement of the propeller (1) and damping devices of the hydraulic or viscoelastic type, such as in the example shown in FIG. 1b, hydraulic stops (121, 122), so as to slow down all the movement or part of the oscillation movement of the propeller (1 ). The oscillating movement of the propeller (1) is braked by the two hydraulic stops (121, 122) fixedly mounted on the hub (12) of the rotor and symmetrically with respect to the drive shaft (ω), as illustrated in Figure 2a. Thus the helix (1) can oscillate, as illustrated in FIG. 2b, between so-called extreme angular positions (A), these extreme angular positions (A) being determined as soon as the stops (121, 122) come into contact with each other. the drive shaft (ω) of the wind turbine, as shown in Figure 2c.

The angle (δ) that the hinge axis (Δ) of the hinge element (123) with the normal (N) to the axis (γ) of the blades (10, 11) is substantially understood between 40 and 85 ° relative to the normal (N) to the axis (γ) of the blades (10, 11). One of the advantages of this angle (δ), as illustrated in FIG. 3, is that it allows the blades (10, 11) to correct automatically and in a favorable direction their angle of attack (oc) by relative to the wind, the angle (α ¹⁾ corresponding to the corrected angle of attack with respect to the angle (α) when the impeller (1) is in its original position, so as to reduce the amplitude of the oscillation movement of the helix (1) and in particular the movements or oscillation movements occurring at the end of the blades (10, 11). Indeed, as illustrated in Figure 3b, this angle (δ) allows a coupling between the oscillation angle of the propeller (1) and the angle of incidence of the blades (10, 11). This coupling is such as to stabilize the aerodynamic propeller (1) with a reduced oscillation amplitude of a ratio 2 to 5 compared to that of the propellers of the prior art. This reduction in the oscillation amplitude of the blades (10, 11) makes it possible to position the oscillating helix (1) closer to the support mast. In addition, this angle (δ) makes it possible to reduce the forces on the elastic devices and damping devices of the oscillating propeller (1). Finally, this angle (δ) considerably reduces the dimensioning of the hydraulic stops (121, 122) for braking the oscillation movement of the propeller (1).

Hereinafter will be described the operation of the oscillating propeller (1) according to the invention which has just been described.

With reference to FIG. 2b, the helix (1) can thus oscillate or pivot via the rotation of the articulation element (123) between its extreme angular positions (A) limited by the two hydraulic stops (121, 122). while having the usual rotational movement due to the wind energy so as to convert the wind energy into electric or mechanical energy, this rotational movement of the propeller (1) driving an electric generator through a drive axis (Δ).

Between its extreme angular positions (A) and a part of the oscillation movement of the propeller (1), the propeller (1) can oscillate "freely" in a so-called "free" oscillation zone, which allows canceling the bending phenomenon on the driving axis (ω) as long as the amplitude of the oscillation movement is less than this free oscillation movement. It should be noted that the so-called "free" oscillation zone of the helix (1) is large enough for the amplitude of the oscillation movement to be recorded in this so-called "free" oscillation zone of the propeller. (1) as long as the wind turbine is operating normally. Beyond this "free" oscillation zone, ie for an excessive oscillation movement of the propeller (1), a damping device dampens this excessive oscillation movement which can be generated for example by a sudden change in wind direction. The damping device of the hydraulic type is equipped with a device called "force limiter" which makes it possible to maintain the braking force of the oscillating movement of the propeller (1) in intensities that are bearable by the structure of the wind turbine. In addition, this hydraulic damping device is designed in such a way that its effect increases when the oscillation movement increases, which makes it possible to maintain the braking efficiency throughout the damping of the excessive oscillation movement of the helix (1).

One of the advantages of the invention is that the oscillating propeller (1) of the two-bladed aerator makes it possible to considerably reduce the aerodynamic stresses exerted on the aerogenerator enabling a significant gain in weight and cost. It should be obvious to those skilled in the art that the present invention allows embodiments in many other specific forms without departing from the scope of the invention as claimed. Therefore, the present embodiments should be considered by way of illustration, but may be modified within the scope defined by the scope of the appended claims, and the invention should not be limited to the details given above.

Claims

1. Propeller (1) oscillating a wind turbine of the type with two blades (10, 11) mounted symmetrically with respect to the center of a hub (12) of a rotor, the two-bladed aerator being erected at the so-called end high of a support mast and the said lower end of the support mast anchored to the ground characterized in that the hub (12) is mounted to rotate with a drive shaft (ω) of the wind turbine and articulated manner via a hinge member (123) to the drive shaft (ω) of the wind generator so as to drive an electric generator implanted in a nacelle, the hinge pin member (123) (Δ) perpendicular to the drive axis (ω) of the aerogenerator forms an angle (δ) with the normal (N) to the axis (γ) of the blades (10, 11) to allow a movement of oscillation of the helix (1) along the axis of articulation (Δ), intermediate elements (124) are provided between the hinge element (12) 3) and the hub (12) in circularly shaped orifices (125) formed on the lateral surface of the hub (12) along the hinge axis (Δ) of the hinge element (123);

the hinge member (123) being of substantially cylindrical shape or the hinge assembly constituting an assembly substantially forming a cylinder;

the intermediate elements (124) being of elastomer and reinforced by rigid lamellae of metal or textile or composite to allow the rotation of the hinge element (123) in the hub (12) of the rotor ensuring the oscillation of the propeller (1), these spacer elements (124) deforming as a function of the oscillation movement of the propeller (1) to reduce the mechanical stresses exerted on the structure of the wind turbine; and

the oscillating propeller comprising resilient devices provided to exert an elastic restoring force on all or part of the oscillation movement of the propeller (1).

2. propeller (1) oscillating an aerator according to claim 1, characterized in that the elastic devices are springs or pads elastomer.

3. Propeller (1) oscillating an aerogenerator according to claim 1 or 2, characterized in that it comprises damping devices provided for braking all the movement or part of the oscillation movement of the propeller (1), the damping devices being of hydraulic or viscoelastic type.

4. propeller (1) oscillating a wind turbine according to one of claims 1 to 3, characterized in that at least two hydraulic stops (121, 122) are fixedly mounted on the hub (12) of the rotor and symmetrically with respect to the drive shaft (ω) for braking the oscillation movement of the propeller (1) -

5. propeller (1) oscillating a wind turbine according to one of claims 1 to 4, characterized in that the angle (δ) is substantially between 40 and 85 ° relative to the normal (N) to the axis ( γ) of the blades (10, 11) and makes it possible to correct the angle of attack (α) of the blades (10, 11) with respect to the wind.

6. Operation of a propeller (1) oscillating a wind turbine according to one of claims 1 to 5 comprising a hinge element (123) for transmitting the engine torque of a hub (12) of the propeller (1 ) to a drive shaft (ω) of the wind turbine to drive an electric generator implanted in a nacelle characterized in that the propeller (1) can oscillate along the axis of articulation (Δ) between said angular positions extremes (A) being determined as soon as a hydraulic stop (121, 122) fixedly mounted on the hub (12) of the rotor is in contact with the drive shaft (ω) of the aerogenerator and the oscillating movement of the propeller (1) making it possible to reduce the aerodynamic stresses on the aerogenerator is ensured by the rotation along the axis of articulation (Δ) of the articulation element (123) ).

7. Operation of a propeller (1) oscillating according to claim 6, characterized in that the propeller (1) can oscillate "freely" on a part of its oscillation movement between the two extreme angular positions (A) both that the amplitude of the oscillation movement is less than this free oscillation movement.

8. Operation of a propeller (1) oscillating according to claim 6 or 7, characterized in that beyond the oscillation movement "free" that is to say for an excessive oscillation movement of the propeller (1), a damping device of hydraulic type is used to dampen this excessive oscillation movement.