FR2568948A1 - Articulated bearing structure for horizontal-axis wind machines - Google Patents

Abstract

The invention relates to a device intended to support horizontal-axis wind machines and to improve on all the currently-existing solutions, especially by protecting the machines during sudden gusts of wind and by furthermore permitting easier handling of the machines to facilitate maintenance operations. In fact, the structure proposed by this invention is articulated in several segments which are integral with one another in such a way that the machine may occupy in space all of the positions delimited by the dimensions of the support. This bearing structure withstands the effect of excessive wind pressure like a shock absorber by virtue of the action of a spring, but once the spring is released, the structure can be lowered to the ground by a simple and completely safe manoeuvre.

Description

 The invention relates to improvements made to the load-bearing structures for wind machines, in particular with a horizontal axis, and more particularly relates to the architecture of the load-bearing structure of such machines.

 Before approaching the main provisions of the invention, it is worth recalling the difficulties encountered during the design and operation of the load-bearing structures of wind turbines.

 The term “wind turbine” means more specifically the energy-producing rotor here.

The observation of the behavior of many wind turbines in operation1 in particular under the effect of strong winds, reveals two essential remarks
- The first follows from the analysis of the numerous operating incidents observed8s, Indeed, most incidents, even accidents going as far as the destruction of the machines1 are due to the fact that none of the machines observed were provided with devices allowing them to cope with sudden accelerations of the wind. These accelerations cause real shocks on the machines, especially at the propeller blade attachments because the propeller pitch regulation systems cannot react quickly enough to avoid the impact effect on the propeller at the moment. overpressure due to sudden acceleration.

 - The second remark concerns the difficulty of access to the machines, almost all of the machines are located on fixed and rigid structures making maintenance and repair work excessively difficult and painful, and even sometimes acrobatic.

 Such an operation should last only a few minutes and should only be carried out by a single operator, while the known and listed means for visiting a machine and grounding it take more than one or two hours. and require multiple operators.

 It should also be remembered that such machines are put in place to be used for several years, even several tens of years.

 However, such machines have their load-bearing structure subjected to very significant mechanical fatigue due to sudden acceleration of the wind.

 It should be specified, in the phenomena undergone by the wind machines that "the wind", term which defines and materializes the displacement of the air, is a phenomenon which is, neither constant, nor regular, and is essentially variable.

This phenomenon is however measurable and even predictable by meteorological observations which can, within a few hours of intervals, define the approximate force according to graduations known under the name of "Beaufort scale". But, which do not specify these forecasts, it is that, as soon as the wind reaches a force higher than the force 7 and 8 (approximately 15 m / s) it can undergo sudden and very important variations going from 2 to 3 m / s until 20 m / s or more, in seconds. (i)
These accelerations, generally called "oversales" or "strong gusts", cause damage on roofs, chimneys, trees, plantations and, of course on wind turbines, especially at the level of the propeller blades
Indeed, the overpressures are so sudden that the regulation systems which act on the pitch of the propeller blades, do not react quickly enough to avoid these overabundant stresses, not only on the propeller but on the load-bearing structure of the the best known example being the destruction of the 100 KW machine on Ouessant Island in 1981.

 The overselling causes vibrations on the different parts of the structure (each with its own frequency), which when they enter into resonance, cause a phenomenon of amplification generally fatal to the weakest parts of the machine or structures. carriers.

 To remedy these phenomena, manufacturers are required to provide structures comprising very large safety coefficients which entail additional manufacturing costs without however.

increase the ease of visit.

(1) These phenomena can be verified on the graphic recordings of the anemometers of all the semaphores of the French Navy scattered on the French coast as well as in all the stations of the
National meteorology.

Attempts have been made to obviate these drawbacks by generally adopting tubular pylons in elements assembled by bolting onto the end flanges of the tubes. The verticality and rigidity of the pylon is ensured by several layers of guy wires made of steel cables which occupy a large space on the ground. The foot of the pylon can be mounted on a pivot hinge and the machine can be lowered to the level of the n ', , ground by slackening the shrouds opposite the screed and retaining the pylon mass using a winch or a jack This operation is always long and tedious and is not without danger.

finally the shrouds are a cause of vibrations at the top of the pylon, in strong wind.

We will find the same drawback for the replacement of the machine and the lifting of the pylon. It may be added that an administrative service which operates such machines can count on specialized personnel normally remunerated to carry out such maneuvers.
but one can imagine the situation of a particular owner of a wind machine for whom such operations then pose real problems and cause intervention costs for companies or specialized personnel which are quite regrettable and prejudicial to the public opinion on the merits of the exploitation of wind energy.

 For the machines of higher power (from 100KW to 1 or 2 MW) the manufacturers are brought to envisage in a form4 fixed at the top of the support in an irremovable way a specialized cabin, generally called "nacelle11", of sufficiently large size to allow not only the housing of active devices: supporting frame, main shaft of the electric generator rotor (which can weigh a ton or more), speed multiplier, and other accessories, but also the parking and the evolution of one or two maintenance agents and this several tens of meters above the ground.

 The difficulty of setting up such a nacelle and its cost are prohibitive because it must also be fitted with rotation devices, auxiliary motor for regulating the propeller blades, control board for relays and transfers, etc.

 In another form, the nacelle can be equipped with devices making it movable vertically along the pylon, using hydraulic or pneumatic cylinders with central oil or corresponding air, to allow the visit of the material to floor during major repairs. However, all rotating machines require such interventions, especially during the testing or development periods.

 The solutions exposed above are not exhaustive but they are the most used by the manufacturers, in a genep.ale way it can be affirmed that there is not currently on the wind market, of supporting structure full satisfaction for normal operation of the machine in all circumstances. This fact is one of the factors which slows down the use of this energy because potential buyers are aware of the operating difficulties.

There is therefore a strong need for an improved structure which:
- on the one hand, provides a technical solution to the problems of mechanical resistance due to the random wind regimes.

 - and on the other hand, provides a solution to the difficulties of operation and maintenance.

The invention meets this need. To this end, it relates to a support structure for wind machines with horizontal axis, characterized
in that it is made up:
- on the one hand, a vertical stationary support (1) whose height
is substantially equal to half the height of the level where the rotor (R) of the machine operates, this support preferably being self-supporting, immobilized on the ground.

- on the other hand, a self-orientable mobile assembly (2) disposed at the top of the stationary support (1) and capable of supporting the wind machine (R), said crew being kinematically integral with the stationary support so as to be able to evolve in two movements, one in a horizontal plane over 3600, the other in a vertical plane, so as to be able to occupy in particular two extreme positions in this vertical plane
one high, for dynamic operation of the machine, the other low, for maintenance operations.

Thanks to this constructive arrangement, it eliminates the subject of construction and occupation on the ground, it eliminates a large part of the stresses applied to the stationary support, it reduces the
effects induced on the rotor of the machine by reduction of turbulence finally, for the exceptional oversales and for the maintenance, one creates the possibility of bringing quickly to the ground the wind machine.

According to an embodiment:
- the moving part consists of a rotating chase (2) r-mounted on a slewing slewing ring (2.3), placed at the top of the
stationary support, and at least one lever arm formed by two
sections extending on either side of a horizontal axis (3.6) allowing movement in the vertical plane, this arm carrying at one of its ends the wind machine and at its other end a counterpods (3.7), said arm being associated with a return means such as a spring or shock absorber (6) intended to hold:
on the one hand, the support arm (3) in the high dynamic operating position of the machine,
- on the other hand authorize an angular movement in the direction of the ground either for maintenance operations, or to neutralize the operation of the machine in the event of exceptional overselling.

According to another embodiment:
The moving assembly is made up, in addition to the rotating casing, of two separate lever arms, respectively (5.4) in parallel arrangement and each carrying a pivot axis (3.6 - 4.1) integral with the rotating frame, these two lever arms being further connected by a connecting rod (5) forming with the pivot axes (306 - 4n1) a deformable quadrilateral.

Other advantages and characteristics will become apparent on reading the following detailed description of several embodiments given here by way of example and shown in the accompanying drawings, in which:
Figure 1 is a side elevation showing the kinematics of the machine structure.

 Figure 2 is a front elevation of the structure of Figure 1.

Figure 3 is a cross-sectional view along A-A1 of Figure 1
FIG. 4 is a side elevation view showing a variation of execution of FIG. 1.

 FIG. 5 is a sectional view showing the fixed shaft of the structure according to FIG. 4.

 FIG. 6 is a side elevation view showing another variant of FIG. 1.

 FIG. 7 is a partial cross-sectional view of FIG. 6.

 FIG. 8 is a sectional view along A, A 'of FIG. 7.

 Figure 9 is a side elevational view of an embodiment of the structure preferably applied to high power machines.

 FIG. 10 is a top view of the structure of FIG. 9.

 Figure al is a side elevational view showing an alternative embodiment for high power machines.

 DESCRIPTION OF THE EMBODIMENT OF THE INVENTION.

 The sketch illustrating the present invention in diagrams 1-2-3 shows the various technical parts which are to provide the improvements described above, according to various types of support and according to several solutions for fixing the wind machine to the mobile support.

 In Figure 1 is exposed the case of a support, among the simplest, for low power machines (2 to 6oo m in diameter for example).

 This support consists of 5 essential parts numbered from 1 to 5, the accessories of each part mentioned in the text being numbered in decimal mode (1,2 - 1,3 etc ...).

 Exhibit 1 represents the base pylon which is fixed to the ground by means of a foot plate (1,2), supported by stiffening gussets (t, 3) welded to the central tube (1,1) , this plate making it possible to ensure a better seat of the pylon on the solid foundation, the fixing on the solid being ensured by bolting on the anchoring irons.

 The pylon will in principle consist of a metal tube calculated so that it is self-supporting and that it is able to resist the overturning moments applied to the top.

 It will advantageously be constructed of sheet steel because this solution allows the smallest section compared to the constraints required.

 It can nevertheless be constructed of other materials, including in particular. in reinforced concrete1 or in prefabricated elements fitted one above the other and reinforced by a set of steels stretched by bolting between the base of the base and the top plate. This solution leads to the construction of a foundation assembly with anchoring irons for tensioning steels, but it can be economical compared to the steel pylon.

 It should be noted at this point in the description that the solution described is the simplest, but the invention is adaptable to all types of existing fixed supports such as masonry towers or old windmills, provided that their dimensions are compatible with the interest of the project.

 (1) or welded or bolted lattice pylons.

 Part no. 02 is the support part which serves as the basis for the moving equipment. This part can be designed in several ways: the drawing presented in Figure 1 offers one of the simplest solutions. This part comprises: a base plate (2,1) whose shape will advantageously be circular, in particular for small machines, on which two plates (2,2) will be fixed perpendicularly for use in fixing the axes of rotation to the movable arms in the vertical plane (parts 3 and 4). This plate (2,1) is fixed by bolting to the orienting ball crown (2,3) which is itself integral with the plate at the top of the base pylon, part n01. This ball crown allows rotation over 3600 in the horizontal plane of the entire moving assembly.

 The part en03 is a beam with two arms forming a fork or compass, connected at their top, therefore integral with each other, being connected by several spacers (3,3), (3,4), (3,5 ). This two-arm beam has two lever arms, on either side of the axis of rotation (3,6). The downstream arm, relative to the wind bed, is intended to carry the wind machine itself at the top, using an intermediate piece (5) which, as will be shown below9 is not not indispensable.

The upstream arm, relative to the wind bed, is intended to carry a counterweight (3,7) whose role is to compensate for the weight of
a machine at / level, however lower by a few daN (1)
It should be specified, at this point in the description, that the legs of the fork will be thin beams which will have every advantage in being aerodynamically shaped following a symmetrical section type NACA 0012 or thicker. This construction detail has the advantage of do not create turbulence on the area swept by the propeller of the machine itself, very important advantage compared to all existing pylons. (Fig. 3)
The part no. 4 is a second beam which may have one or two arms, in the form of a fork, which can pivot around the axis of rotation (4,1). This second beam is intended to constitute with the beam n031 a quadrilateral which may be of the parallelogram type deforming so as to allow the wind machine to move always parallel to the plane of rotation of its propeller.

(This part is not essentially essential).

 The part 5 is a terminal part which supports the machine itself, it is mounted on the beams 3 and 4 by means of two axes of rotation (5.1) and (5.2).

(1) Only the spring (6) has the role of bringing it back to its most level
Student.

 The set of mechanical parts 2, 3, 4, 5, 5 forms a homogeneous but deforming articulated mechanical unit, the arms constituting it being two by two parallel.

 This assembly must allow the wind machine to occupy in space all the positions delimited by the circular deflection of the beams 3 and 4, but keeping its axis of rotation always parallel to itself.

It should be specified at this point in the description that the deforming parallelogram consisting of the connecting rods 3 and 4 can be reduced to the single connecting rod 3 as shown in FIG. 41, the condition necessary to allow this assembly being that the wind machine is suspended at the end of the connecting rod 3, at its center of gravity. In fact, if the machine is mounted on a horizontal axis of rotation passing through its center of gravity, it will remain in a position of equilibrium depending on the position of the carrying arm, thanks to the gyroscopic inertial force due to the rotation of the machine propeller. This solution requires the suspension of the machine with balancing counterweight relative to the support axis. It may represent a saving character compared to
prece en e the parallelogram solutio ge with two connecting rods being only an accessory to the very idea of the invention which is to suspend the wind machine from a mobile arm in two planes: horizontal, with rotation on 36001 and vertical with rotation out of approximately 1600 - so as to benefit from the improvements referred to at the beginning of the presentation.

 The part n06 is a spring with high elongation, shown in dashed lines in FIGS. 2 and 5, the action of which is combined with that of the counterweight. This spring 6 will advantageously be fixed in the axis of the fixed pylon. The upper end of the spring is connected to a spacer (3.3) (for example) of the connecting rod 3 via a connecting cable (6.3) and return pulleys (6, i) and (6.2).

The lower end of the spring being integral with a winch piece n07 - rotating, fixed inside or outside the pylon via a connection cable <C.4)
The action of this spring is to compensate for and dampen the excess wind pressures on the propeller, mentioned in the first part of the presentation, and to bring the machine back to its highest position.

If it were found that the extension of the spring allowed the machine to move too quickly, under the action of gusts, pneumatic (or friction) shock absorbers could be added, so as to slow down the movement of the support arm
Finally the winch n07 has a double role: first of all, allows
circular
be to adjust the tension of the (or springs) using a rack
with ratchets, and then after releasing the spring tension,
lower the carrying arm (or arms) of the machine to
desired level near the ground. This winch can be installed indoors
laugh of the fixed pylon, with an external steering wheel9 or the winch assembly
steering wheel entirely outside.For very powerful machines
this, therefore of high weight, the winch can be driven by a
large-scale auxiliary motor placed inside the
pylon.

So this is the simplest presentation of the defor
mant illustrating the present invention.

This presentation can obviously be adapted to the circumstances.
these premises according to the type of wind machine used and according to
basic support.

Another presentation is illustrated in FIG. 9 in the case
where the basic support is an old windmill to which the owner
etaire would like to adapt a modern wind machine in front of him
provide the necessary energy, either for heating9 or for lighting
building age. This is the typical case of using an existing pylon,
where the movable arms are articulated in several segments.

In this form of the invention shown schematically in Figures 9 and 10
the support arm of the wind turbine machine (3) and the support arm of the
counterweights (4) have been separated so as not to have to
works with long beams. Both arms are provided
parallels: 3.1
-the machine carrying arm can pivot around a transverse axis (1)
secured to the chassis rotating on the horizontal ball crown.

- likewise) the counterweight carrying arm can pivot around it
transersal axis (4,1) integral with the rotating chassis this axis forming
axis of symmetry, so as to obtain two equal lever arms
and sprawls from the swivel area. This arm is made integral with the machine carrying arm by means of two connecting rods) fixed to
the end of the upper lever arm of part 4. (cf. note Y page 10
The whole re-reads well the deforming simplicity described in the pages
previous; only the weight of the counterweight fixed to the lower end of the arm (4) is to be determined according to the following criteria:
of the arm
the weight of the machine and the ratio of the lever arms / carrier of the
wind turbine machine, on either side of the cross-link (5).

cf: note y
(1) in the horizontal plane.

Another form of the invention can be presented by using modern materials such as pneumatic cylinders to replace the spring 6 and the winch 7.

Indeed the simplicity of the figure (11) illustrates well this other form of the invention: the fixed base pylon, is in 1, the mobile equipment is in 2, comprising the rotating chassis (2.1.

and the two perpendicular flanges (2,2) carrying the pivot axes (3,1) and (4,1) of the connecting rods 3 and 4. These two connecting rods are parallel, the - upper base of the parallelogram being integral with the wind machine herself.

The main support arm is connected to the flanges (2,2) by the intermediary of one or two pneumatic cylinders (8) themselves secured to the flanges by the intermediary of the pivot axis (8, i) and secured to the support arm through the pivot axis (8,2).

This solution obviously implies that the cylinders are constantly supplied by an air reservoir which is itself maintained
(10) in pressure by a compressor located inside the pylon.

It can then be assumed that the machine produces the electrical energy necessary for the operation of the compressor from an energy reserve such as a storage battery maintained at constant charge.

This solution also involves the use of a rotating joint tolerating the nominal pressure of the compressed air at the junction of the fixed supply lines for the pneumatic cylinders inside the pylon (1) and the lines turning with the crew. mobile-.

 Note Y: this note relates to the connecting rod 9 on diagrams 9 and lo. This connecting rod (9.1 and 9.2 in diagram 10) is integral with both the connecting rod 5 and the wind machine by means of axes 9.3 and 9.4.

 Its purpose is, in the case of large machines, to cause the progressive tilting of the machine during the lowering operation towards the ground, so that the plane of the propeller is parallel to the plane of the ground in the position the lowest.

Note Z: The load-bearing beam of the counterweight in its most vertical position can be supported on the fixed support by the intermediary of one or more pneumatic tires (3 * 9 --Fig.4) or (4.3 Fig.9 ) so as to facilitate the rotation of the moving assembly during variations in the wind direction. The rollers can be replaced by a sliding strip made of synthetic material (3.9 - Fig. 1).

Claims (7)

10) Supporting structure for wind machines with horizontal axis characterized in that it consists of a part,  a vertical stationary support (1) whose height is substantially equal to half the height of the level at which the rotor (R) of the machine operates, this support preferably being self-supporting, and immobilized on the ground,  on the other hand, a self-orientable mobile assembly (2) disposed at the top of the stationary support (1) and capable of supporting the wind machine (R), said crew being kinematically integral with the stationary support so as to be able to evolve in two movements one year horizontal plane on 3600, another in vertical plane so as to be able to occupy in particular two extreme positions in this vertical plane, one high for the dynamic exploitation of the machine, the other low for the operations of maintenance.  o) Supporting structure according to claim 1 characterized in that the movable assembly consists of a rotating chassis (2) on an orientation ring (2,3), without auger, available at the top of the stationary support and at least one lever arm formed by two sections extending on either side of a horizontal axis (3.6) allowing movement in the vertical plane, the arm carrying at one of its ends-the wind machine and at its other end a counterweight (3.7), the said arm being associated with a return means such as a spring or shock absorber (6) intended to maintain on the one hand the carrying arm (3) in its high position for dynamic exploitation of the machine, on the other hand authorize an angular movement in the direction of the ground either for maintenance operations or to neutralize the operation of the machine in the event of exceptional overselling.  3o) supporting structure according to claim 1 characterized in that the movable assembly consists, in addition to the rotating frame, of two separate lever arms respectively (3 - 4) in parallel arrangement and each carrying a pivot axis (3.6 - 4.1) integral with the rotating chassis (2), these two lever arms being further connected by a connecting rod (5) forming with the pivot axes (3.6 -'4.1) a deformable quadrilateral. 40) Supporting structure according to claims t and 3, characterized in that the beam 4 of mobile equipment carries at its base a counterweight (3.8) while the beam t3) carries at its free end the wind machine.  5) Supporting structure according to any one of claims 7 to 4 characterized in that the levers of the movable assembly are each time constituted by two symmetrical parallel arms braced to form each time a rigid beam. 60) carrying structure according to any one of claims i- a 5 characterized in that qur, the beam of the movable equipment which carries the counterweight is equipped, near its free end with a stop (3.9) preferably rolling bearing on the body of the stationary support. 7) Carrying structure according to revendicatwon 1, characterized in that the wind machine of the moving assembly, comprises in its center of gravity a pivot (802) allowing, by means of a set of fixed pulleys (8.1 - 8.3 ) in rotation and an endless link target (8.4) maintaining the wind machine on a horizontal axis whatever the angular position on the arm of the carrying lever. 80) carrying structure according to claims 1 and 3 characterized in that the wind machine is freely fixed at the end to the carrying lever arm (5) by means of a horizontal axis with free pivoting coinciding with the center of gravity of the machine. 90) Support structure according to any one of claims 1 to 8 characterized in that it comprises a control means acting on the angular displacements of the support beam in the vertical plane. 100) Supporting structure according to any one of claims 2, 3,4,5, characterized in that the beams 3-4 and connecting rods 5 and 9 are profiled according to an aerodynamic profile of symmetrical preference.