EP2037085B1 - Hebel für verstellbare Statorschaufel einer Turbomaschine - Google Patents

Description

The present invention relates to turbomachines, as used in the aeronautical field. It relates to turbomachine variable valve stator blades, including gas turbine engine compressor, and more particularly to the control levers rotating such blades around their pivot.

The gas turbine engines include an air compressor section supplying a combustion chamber that produces hot gases driving the turbine stages downstream. The engine compressor comprises a plurality of bladed movable wheels, separated by successive stages of stator bladed wheels forming gas flow rectifiers. The blades of the first stages of the stator are generally variable pitch, that is to say that the angular position of the blade around its radial axis, pivoting, is adjusted according to mission points to improve the compressor efficiency. The orientation of the variable-pitch vanes is effected by means of a mechanism designated variable-pitch mechanism or VSV for Variable Stator Vane. There are several configurations of these mechanisms, but overall they all include one or more jacks fixed on the motor housing, synchronization bars or a control shaft, rings surrounding the motor and arranged transversely to the axis of the latter and substantially axial levers, also referred to as connecting rods, connecting the rings to each of the variable-pitch vanes. The cylinders rotate the rings around the motor axis, which rotate synchronously all the levers around the blade pivots.

These mechanisms are subject to both aerodynamic loads applied to the blades, which are important, and to forces resulting from friction in the various links. In particular, the levers are subjected to static loadings in bending and torsion and to dynamic loads. All of these charges can reach levels that are likely to be harmful; their cumulation in particular can lead to the formation of cracks or other damage. Given the requirements of mechanical strength and service life assigned to them, the amplitudes of the vibrations induced by these charges that these parts undergo must remain low.

Parts are designed and dimensioned to avoid the presence of critical modes in their operating range. In practice, however, there are still some crossovers and experience engine tests carried out at the end of the design cycle of the parts, showed that, in some cases, this could lead to initiations of cracks in the levers. The sizing of the part must then be reviewed and modified which is particularly long and expensive. As a result, the vibration response levels must be predicted as early as possible in the sizing cycle so that corrective action can be taken as early as possible in the design process.

Prior art includes teaching of patents EP 110918 which describes a method for increasing the life of a drive ring of the variable pitch vanes of an engine by minimizing the relative movements resulting from the vibrations of the motor first detuning the control ring and then introducing vibration damping means between the different elements of the control mechanism of the variable geometry; EP1820941 which describes a vibration damping means in a variable geometry blade control device, consisting of springs arranged around the inner pivot opposite the drive mechanism; EP1111196 which describes a control device for variable pitch vanes in the turbine of a turbocharger driven by the exhaust gas of an internal combustion engine.

The present invention relates to a means providing structural damping in order to reduce the levels of deformation seen by these parts in operation and more particularly to reduce the dynamic responses of drive levers in rotating blade vane variable under synchronous or asynchronous solicitation, aerodynamic origin or not, by a contribution of dynamic damping.

The invention thus relates to a rotary drive lever around its pivot of a stator vane with a variable turbine engine timing comprising three zones: a first attachment zone to a lever driving member, a second zone attaches to said variable-pitch stator vane, and a third elongated zone between the first zone and the second zone. The lever according to the invention is characterized in that on at least one surface portion of at least one of said zones of the lever, a vibration damping laminate is applied, the laminate comprising at least one layer of viscoelastic material in contact with said surface portion and a backing layer of rigid material.

The drive member is generally a ring surrounding the housing of the turbomachine, itself rotated about the axis thereof by a jack. The lever is generally mounted at the end of the blade so as to drive it by its platform.

The laminate is either adhered to said surface portion or maintained applied mechanically.

To ensure the robustness of these parts vis-à-vis the vibration fatigue, the solution of the invention is therefore to add to the structure specific devices for dissipating vibration energy.

The originality of the present invention is based on the use of tile-shaped laminates composed of a viscoelastic sandwich with a layer of constraints bonded or fixed on the structure, whose function is to dissipate the vibratory energy of the room.

The dissipation of this energy fraction is obtained by shear deformation of the viscoelastic material, between the structure which deforms under dynamic stress and the inertia-driven stress layer. These tile-like laminates being fixed or glued on the faces of the lever directly dampen the modes of the structure, without disrupting the overall performance of the machine.

The solution of the invention has the advantage of allowing an increase in the structural damping of the metal part in question without having to resize, and thus reduce the costs and development time and development associated with the product.

It also allows the widening of conventional design areas bounded by the satisfaction of alternating load-bearing services and, indirectly, mass gains.

The invention is applicable regardless of the type of dynamic loading: crossing with motor harmonics or asynchronous excitation.

According to one embodiment of the invention, said zone of the lever on which the laminate is applied is the third zone. According to the technical considerations, said surface portion on which the vibration damping laminate is applied completely covers said third zone.

According to another embodiment, said lever zone comprises the second and third zones.

According to another embodiment, the lever comprising a radially upper face and a radially lower face, the laminate is applied to at least one surface portion of said radially lower or upper faces. For example, at least one of said radially lower or upper faces is flat.

According to another embodiment, the second zone of the lever comprising a face at a level radially different from a face of the third zone, the vibration damping laminate covers at least partially a surface portion of said face of the second zone and a surface portion of said face of the third zone. More particularly, the laminate comprises an intermediate portion between said second zone surface portion and said third zone surface portion. Optionally, said intermediate portion of the vibration damping laminate is perforated.

According to one embodiment, the vibration damping laminate is strip-shaped with a width smaller than the width of the third zone. Optionally, the lever comprises at least two strips of vibration damping laminate. More particularly, the lever comprises at least two vibration damping laminate strips arranged parallel to each other.

According to one embodiment, the laminate consists of a stack of viscoelastic layers and alternate rigid layers, and the characteristics of the viscoelastic material vary from one layer to another or the characteristics of the viscoelastic material are the same. one layer to another and the characteristics of the rigid material vary from one layer to another or the characteristics of the rigid material are the same from one rigid layer to another.

The invention also relates to a turbomachine comprising at least one such rotary drive lever around its pivot of a variable-pitch stator vane. More particularly it is a gas turbine engine compressor comprising at least one such rotary drive lever around its pivot of a variable-pitch rectifier blade.

• La figure 1 représente schématiquement un turboréacteur en coupe axiale susceptible d'incorporer un levier l'invention ;
• La figure 2 montre en perspective la partie du moteur de la figure 1 correspondant à un étage de redresseurs au niveau du compresseur et comprenant des aubes de stator à calage variable ;
• La figure 3 montre un levier d'entraînement des aubes de stator à calage variable de l'étage de redresseurs de la figure 2 ;
• La figure 4 montre en coupe le stratifié d'amortissement de vibrations appliqué conformément à l'invention sur un levier de la figure 3 ;
• Les figures 5 et 6 montrent, l'une en perspective l'autre en coupe le long de celui-ci, le levier de la figure 3 sur lequel est appliqué le stratifié d'amortissement de vibrations ;
• Les figures 7 et 8 montrent, l'une en perspective l'autre en coupe le long de celui-ci, un autre mode d'application du stratifié d'amortissement de vibrations sur le levier de la figure 3 ;
• Les figures 9 et 10 montrent, l'une en perspective l'autre en coupe le long de celui-ci, un autre mode d'application du stratifié d'amortissement de vibrations sur le levier de la figure 3 ;
• Les figures 11, 12 et 13 montrent le levier de la figure 3 avec application de stratifiés d'amortissement de vibrations sur les faces radialement inférieure et radialement supérieure de celui-ci ;
• Les figures 14 et 15 montrent un autre mode de réalisation de l'amortissement au moyen de stratifiés.

The invention will now be described in more detail with reference to the accompanying drawings in which:

• The figure 1 schematically represents a turbojet in axial section capable of incorporating a lever the invention;
• The figure 2 shows in perspective the motor part of the figure 1 corresponding to a rectifier stage at the compressor and including variable-pitch stator vanes;
• The figure 3 shows a variable-stator stator vane drive lever of the rectifier stage of the figure 2 ;
• The figure 4 shows in section the vibration damping laminate applied according to the invention on a lever of the figure 3 ;
• The Figures 5 and 6 show, one in perspective the other in section along it, the lever of the figure 3 on which the vibration damping laminate is applied;
• The Figures 7 and 8 show, one in perspective the other in section along it, another mode of application of the vibration damping laminate on the lever of the figure 3 ;
• The Figures 9 and 10 show, one in perspective the other in section along it, another mode of application of the vibration damping laminate on the lever of the figure 3 ;
• The Figures 11, 12 and 13 show the leverage of the figure 3 applying vibration damping laminates to the radially lower and radially upper faces thereof;
• The Figures 14 and 15 show another embodiment of damping by means of laminates.

On the figure 1 schematically, an example of a turbomachine in the form of a turbofan and double-body turbojet engine is shown schematically. A fan 2, at the front, supplies the engine with air. The compressed air by the fan is divided into two concentric flows. The secondary flow is evacuated directly into the atmosphere without further energy input and provides an essential part of the driving thrust. The primary flow is guided through several stages of compression to the combustion chamber 5 where it is mixed with the fuel and burned. The hot gases supply the different turbine stages 6 and 8 which drive the fan and the mobile wheels of the compressor. The gases are then vented to the atmosphere. Such an engine comprises several stator wheels: a wheel downstream of the fan to straighten the secondary flow before its ejection, stator blade wheels 3 'and 4' interposed between the mobile wheels 3 and 4 of the compressors and distributors 6 and 8 'between the turbine wheels both at high pressure and at low pressure.

We see on the figure 2 a statically variable vane wheel with its drive mechanism, as provided in the first stages of the compressor 4.

This wheel 10 comprises blades 11 arranged radially relative to the axis of the engine 1, and pivotally mounted about radial axes inside a housing sector 12. Each is integral, in rotation about its radial axis , a lever 20 disposed externally to the housing sector. The levers are rotatable about these radial axes so synchronous being driven by an assembly comprising a drive ring 30 surrounding the motor housing and which each of the levers and fixed by its end opposite that of the radial axis on which it is mounted. An appropriate fixing means is for example a pin 21 traversing radially both the ring 30 and the end of the lever. One or more cylinders not shown control the rotational movement of the ring about the axis of the motor. This movement is transmitted to the levers that pivot simultaneously around the radial axes and rotate the stator vanes around these same axes.

The figure 3 shows a lever 20. It is of generally elongate shape with two faces: a radially lower face 20i and a radially upper face 20e. The lower and upper terms describe the position of these faces relative to each other from the axis of the engine when the lever is in place on the engine. There are three areas. The first zone 20A is pierced with a hole in which is slid here the pin 21. The second zone 20B is pierced with a radial orifice through which the lever is mounted on the variable-pitch blade and ensures its rotational drive. It comprises a radially lower face 20Bi and a radially upper face 20Be. The third zone 20C, between the first two, is of elongated shape, thinner than the zone 20B, with a radially lower face 20Ci and a radially upper face 20Ce. The shape of the lever of the figure is only one example. The invention applies to any equivalent form.

The figure 4 is a sectional view of a vibration damping laminate 40. The laminate is in the form of a tile composed of a plurality of layers stacked one on top of the other. According to one embodiment, the laminate comprises at least one layer 42 of a viscoelastic material and at least one layer 44 of a rigid material. The laminate is applied by the viscoelastic layer to the surface 41 of a structure to be damped.

Viscoelasticity is a property of a solid or liquid which, when deformed, exhibits both viscous and elastic behavior by simultaneous dissipation and storage of mechanical energy.

The isotropic or anisotropic elasticity characteristics of the rigid material of the backing layer 44 are greater than those, isotropic or anisotropic, of the viscoelastic material in the desired thermal and frequency operating range. By way of non-limiting example, the material of the layer 44 may be of metallic or composite type, and the material of the layer 42 of rubber, silicone, polymer, glass or epoxy resin type. The material must be efficient in terms of energy dissipation in the expected configuration corresponding to specific temperature and frequency ranges. It is chosen from its characteristic shear modules, expressed in deformation and speed.

According to other embodiments, the laminate comprises several layers 42 of viscoelastic material and several counter layers of rigid material 44, which are arranged alternately. The example of the figure shows, without limitation, a vibration damping laminate having three layers 42 of viscoelastic material and three against layers 44 of rigid material. Depending on the application, the viscoelastic material layers 42 and the rigid material layers 44 may be of equal size or size. When the laminate comprises several layers 42, they may have all the same mechanical characteristics or have different mechanical characteristics from one layer to another. When the laminate comprises several against layers 44, they may have all the same mechanical characteristics or have different mechanical characteristics from one layer to another. The layers 42 and the layers 44 are attached to each other preferably by adhesion by means of an adhesive film or by polymerization.

On the Figures 5 and 6 a first embodiment of the invention is shown. A laminate 40 is applied to the upper face of the zone 20C of the lever 20. The laminate 40 comprises at least one layer 42 of viscoelastic material and at least one counter-layer 44 of rigid material. The laminate is adhered by the layer of viscoelastic material to the lever 20.

According to another embodiment not shown, it can be held in abutment against the surface of the lever by mechanical means: for example, by a clamping device on either side of the part C, by a mechanical connection ( screw / nut, rivet, crimping, or other) passing through the zone 20C of the lever and the laminate, by a pre-stressing effect obtained during assembly by deformation of the geometry at rest: fixation of the zone 55 on the part 20B by the linkage of the lever and prestressed support of the zone 54 on the portion 20 C of the lever.

The laminate extends over the entire surface of the third zone 20C of the lever. Its trapezoidal shape corresponds to the shape itself trapezoidal of the third zone 20C of the lever between the first zone 20A and the second zone 20B. In this example, the surface portion on which the laminate is applied occupies the entire third zone. However, depending on the vibration damping requirements, the extent of the surface portion may be smaller than that of the third zone. Moreover, the thicknesses and the nature of the materials constituting the layers 42 and 44 are determined as a function of the desired damping.

According to another embodiment not shown, the laminate 40 is applied not on the upper face of the zone 20C of the lever but on the lower face 20Ci of the zone 20C of the lever 20. According to another embodiment shown in FIG. figure 11 a vibration damping laminate, 40 and 40 ', was disposed on both sides of the third zone of the lever symmetrically.

According to the embodiment of Figures 7 and 8 the vibration damping laminate 50 comprises a first portion 54 extending over at least a surface portion of the upper face of the third zone C of the lever and a second portion 55 extending over at least a portion of surface of the upper face 20Be of the second zone 20B. In this example, the first portion 54 extends over most of the third zone 20C. Insofar as the upper surface of the second zone is at a level radially higher than the level of the radially upper surface 20Be of the third zone C, the laminate 50 has an intermediate portion 56 connecting the first portion 54 to the second Part 55. This intermediate portion 56 improves the effectiveness of the device by using the shear forces of the viscoelastic layer. The laminate is held against the surface of the lever by gluing for example at least one of the portions 54 and 55. Here again the laminate can be applied to the underside of the lever. According to another embodiment shown on the figure 12 a vibration damping laminate 50 and 50 'were disposed on both sides of the second and third zones of the lever symmetrically.

According to the embodiment of Figures 9 and 10 , the vibration damping laminate 60 comprises a first portion 64 extending over a surface portion of the upper face of the third zone 20C, a second portion 65 extending over a surface portion of the upper face of the second zone 20B. The laminate has an intermediate portion 66 connecting the first portion 64 to the second portion 65. According to this example, the intermediate portion is perforated. The laminate is held against the surface of the lever by bonding for example at least one of the portions 64 and 65. Here again the laminate can be applied to the underside of the lever. According to another embodiment shown on the figure 13 a vibration damping laminate 60 and 60 'were disposed on surface portions of the two faces of the second and third regions of the lever symmetrically.

According to the embodiment of Figures 14 and 15 the laminate is in the form of strips arranged along the lever. The strips comprise a first portion 74 applied on the third zone 20C, a second portion 75 on the second zone 20B and an intermediate portion 76 connecting the two portions 74 and 75.

Claims (13)

1. A lever (20) for rotating about its pivot a turbomachine variable-pitch stator vane comprising three zones: a first zone (20A) for attachment to a lever drive member, a second zone (20B) for attachment to said variable-pitch stator vane, and a third zone (20C) of elongate shape between the first zone and the second zone, wherein a vibration-damping laminate (40, 50, 60, 70) is applied to at least one surface portion of at least one of said zones (20A, 20B, 20C) of the lever, the laminate comprising at least one layer of viscoelastic material in contact with said surface portion and a backing layer of rigid material.
2. The lever as claimed in the preceding claim, in which the vibration-damping laminate (40, 50, 60, 70) is glued to said surface portion.
3. The lever as claimed in claim 1 in which the vibration-damping laminate (40, 50, 60, 70) is kept pressed against said surface portion by a mechanical means.
4. The lever as claimed in one of the preceding claims in which said zone of the lever is the third zone (20C) or alternatively is the second and third zones.
5. The lever as claimed in claim 4 in which said surface portion to which the vibration-damping laminate is applied entirely covers said third zone (20C).
6. The lever as claimed in one of the preceding claims, comprising a radially upper face and a radially lower face, in which the laminate is applied to at least one surface portion, particularly a flat surface portion, of said radially lower or upper faces.
7. The lever as claimed in one of the preceding claims, in which the second zone comprises a face at a level radially different than a face of the third zone, the vibration-damping laminate (50, 60, 70) at least partially covering a surface portion of said face of the second zone (20B) and a surface portion of said face of the third zone (20C).
8. The lever as claimed in the preceding claim, in which the laminate comprises an intermediate part (56, 66, 76), for example holed, between said second zone surface portion and said third zone surface portion.
9. The lever as claimed in one of the preceding claims, comprising at least one vibration-damping laminate (70) in the form of strips, at least two of these, of a width narrower than the width of the third zone, said two strips preferably being positioned parallel to one another.
10. The lever as claimed in one of the preceding claims, in which the laminate is made up of a stack of viscoelastic layers and of rigid layers in alternation, the characteristics of the viscoelastic material varying or being the same from one layer to another.
11. The lever as claimed in claim 10, in which the characteristics of the rigid material vary from one layer to another or are the same from one layer to another or are the same from one layer to another.
12. A turbomachine comprising at least one lever as claimed in one of the preceding claims for rotating a variable-pitch stator vane about its pivot.
13. A gas turbine engine compressor comprising at least one lever as claimed in one of claims 1 to 11 for rotating a variable-pitch flow straightener vane about its pivot.

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