BE1026816B1 - Variable timing system of blades of a stator stage of a compressor of an aircraft turbomachine - Google Patents

Abstract

The present invention relates to a system (1) for variable timing of blades (2) of a stator stage of a compressor (4) of an aircraft turbomachine. The system (1) comprises a ring (5) for synchronizing the variable timing of the vanes (2) to which lateral bearing supports (7) are fixed, each of these bearing supports (7) being set with a ball ( 8) arranged to rest and roll on a rolling wall (9) surmounting it and being configured to be mechanically coupled to a casing (41) of the compressor (4).

Description

Variable timing system of blades of a stator stage of a compressor of an aircraft turbomachine

Technical area

The present invention relates to a variable timing system of blades of a stator stage of a compressor of an aircraft turbomachine.

Prior art

An aircraft turbomachine generally comprises at least one compressor provided with a plurality of stages aligned along an engine axis, each stage consisting of a ring of blades which are movable in the case of a so-called stage "Rotor", or static and provided with a rectifier function in the case of a stage called "stator". The rotor and stator stages are often alternated. Technical parameters such as the dimensions of the blades are determined to adapt the operating conditions of each stage to those of the stages upstream and downstream. In particular, in order to optimize the flow of an air flow between the stages of the compressor, the blades of certain stator stages are “variable setting”, that is to say, steerable, and in particular, of a variable angle of attack relative to a circulation of this air flow in the compressor.

The timing of each of the blades of a stator stage is generally controlled by a displacement unit, for example one or more jacks, to move a ring mechanically coupled to the blades and adjusted circumferentially externally around a compressor casing. The ring is provided with skids allowing it to slide on the casing. Given the temperature differences that may occur between the crankcase and the ring when the compressor is in use, there is sufficient space under the pads to avoid tightening of the crankcase by the ring, which could cause the blocking of the setting the blades.

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- 2 These rings nevertheless have a defect. Indeed, under conditions of use, various forces are exerted on the ring. They are due, for example, to forces exerted by the mechanical couplings between the ring and the blades and / or by the displacement unit. These forces are likely to cause local detachment of the ring from the housing due to the existence of the space under the aforementioned pads. Under conditions of use, this detachment then generates a deformation of the ring and, consequently, a loss of operability of the latter. In particular, the variable setting of the blades can be made impossible.

Summary of the invention

An object of the invention is to provide a system of variable timing of blades of a stator stage of a compressor of an aircraft turbomachine which is more reliable than the ring described in the prior art, and which allows great operability of setting the blades.

To this end, the invention proposes a system for variable timing of blades of a stator stage of a compressor of an aircraft turbomachine comprising:

a variable blade timing synchronization ring configured to be circumferentially adjusted around a compressor housing, and to be mechanically coupled to the blades;

a displacement unit for displacing the ring at least partially circumferentially and / or parallel to a motor axis around which the casing extends;

characterized in that it further comprises:

a plurality of bearing supports fixed laterally to the ring, along the ring, each of the bearing supports comprising at least one hole in which is arranged a ball capable of undergoing a

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- 3 rotational movements on itself, an upper cap of the ball surmounting an opening in the hole;

a plurality of fixed bearing walls for cooperating with the balls of the bearing supports;

each of the rolling walls being configured to overcome externally and parallel at least one of the rolling supports, so as to allow support and / or rolling of the upper cap of the ball of at least one of the rolling supports on each of the rolling walls;

the system being configured to limit movement and / or deformation of the ring in an arbitrary radial direction perpendicular to the motor axis. Typically, the bearing supports are configured to overcome externally in parallel an annular portion of the housing extending circumferentially around the motor axis, and the bearing walls are configured to be mechanically coupled to the housing so as to externally overcome the annular portion of the casing, at a fixed distance from the latter.

The system according to the invention is safe and allows great operability of setting the blades. It takes into account both temperature differences with elements of the compressor, and the various forces exerted on the ring.

Indeed, the system according to the invention provides a ring and a displacement unit comparable to what is known from the prior art. However, the ring according to the invention does not necessarily include skids. This aspect will be discussed later. The ring includes the aforementioned bearing supports crimped with balls. These balls are configured to cooperate with the rolling walls by leaning and rolling over them. The rolling walls constitute rolling tracks for the balls. Their arrangement is such that each

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- 4 bearing support faces a bearing wall, trapping the ball in a radial direction perpendicular to the motor axis in conditions of use. As the bearing supports are fixed laterally to the ring, the latter is able to move at least partially circumferentially and / or parallel to the motor axis under the impulse of the displacement unit, by resting and by rolling on the bearing walls by means of the bearing supports. This support is exerted radially, that is to say, perpendicular to the motor axis, thus limiting any radial movement of the ring. In particular, even if a predetermined space exists between the casing and the ring, the latter will not be able to undergo local detachment relative to the casing or deformation, under the condition of use of the compressor. The balls also make it possible not to constrain a movement of the ring circumferentially and / or parallel to the motor axis, because they allow the ring to slide higher on the rolling walls, and therefore to follow this movement . Consequently, the system according to the invention takes account of the various forces exerted on the ring and makes it possible to prevent its radial deformation under conditions of use. In addition, the system according to the invention makes it possible to leave a space between the ring (which may or may not include pads) and the casing to take account of temperature differences with elements of the compressor, thus avoiding tightening of the casing by the ring.

Advantageously, the system according to the invention also makes it possible to limit the dispersion of a setting of the blades on the stator stage, and therefore to further protect the compressor from air pumping by improving its efficiency, since the setting vanes occurs in a controlled and appropriate manner.

The bearing supports and walls advantageously and preferably constitute a bearing between the casing and the ring which is particularly simple to design and very resistant to wear. If a

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- 5 support and / or a bearing wall is worn or damaged for various reasons, a replacement of this support and / or this bearing wall can be undertaken without difficulty and without requiring complex work on the compressor. Indeed, the supports and the rolling walls are attached to the ring and the housing respectively. It is therefore easy to disassemble and / or replace them.

In addition, the supports and the rolling walls are of low mass. They therefore advantageously do not contribute to a significant increase in the overall mass of a compressor which would include the system according to the invention. In particular, the invention is particularly well suited for other aeronautical applications. It can be installed on any stage of a compressor or a land, maritime or aeronautical gas turbine capable of being equipped with a variable blade timing system.

Preferably, the term "externally" used in the context of this document refers to the exterior of the housing. Indeed, the casing forms a semi-closed envelope of which Γ "interior" is distinguished from Γ "exterior" in that it comprises the stages of the compressor and in that its finished volume. In the context of the present document, it is said that an element external to the casing "externally overcomes" the casing, and that an element external to the casing "externally surmounts" another element external to the casing if there is a directed radial vector perpendicular to the motor axis, from the inside to the outside of the housing, such that this vector intersects both the element and the other element, and that the element is located downstream of the other element the along this vector. In particular, in this case, the element is further from the motor axis than the other element. In other words, it is said that the element is above the other element, itself being above the casing.

Preferably, the supports and / or rolling walls are of a very stiff structure to further limit a radial displacement

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- 6 of the ring. In particular, the supports and the rolling walls preferably face each other in an essentially parallel manner and encloses the balls at least radially.

Preferably, in the context of this document, reference is made to several directions and / or trajectories of movement: "axial" preferably consisting of a direction and / or trajectory of movement being parallel to the motor axis around which the compressor, "circumferential" preferably consisting of a direction and / or trajectory of elliptical movement, more preferentially circular, along a circumference of the compressor, around the motor axis, and "radial" preferentially consisting of a direction and / or movement trajectory perpendicular to the motor axis and to a tangent of a direction and / or circumferential movement trajectory. The terms "radial" and "circumferential" preferably refer to a system of polar coordinates known to a person skilled in the art in each plane perpendicular to the motor axis.

Preferably, the displacement unit is configured to move the ring helically on the compressor housing, around the motor axis. The displacement is therefore both axial and circumferential, and carried out over a small distance measured along a portion of helicoid since the objective of this displacement is to cause a certain change of orientation of the blades of the stator stage by mechanical coupling of the ring with the blades, the latter being preferably produced by means of rods and / or levers.

In the context of this document, the annular portion of the housing preferably does not constitute a physical element, but a zone of superposition of the housing above which the rolling walls externally surmount the rolling supports. This zone circumferentially surrounds the casing and forms an annular portion preferably adjoining the timing synchronization ring.

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- 7 variable blades and being overcome externally by the supports and rolling walls. Preferably, a length of this annular portion corresponds to a length of a circumference of the casing, and a width of this portion measured essentially along the motor axis is less than 10 cm, more preferably, less than 5 cm.

Preferably, the adjustment of the ring on the compressor casing as described above cannot in any case exclude that a positioning and / or a displacement of the ring under the impulse of the displacement unit, takes place either on the crankcase itself, or on a shell external to the compressor coupled to the crankcase.

Preferably, within the framework of this document, the use of the verb "to understand" of its variants, as well as its conjugations, cannot in any way exclude the presence of elements other than those mentioned. Preferably, within the framework of this document, the use of the indefinite article "a", "an", or of the definite article "le", "la" or "I '", to introduce an element n' does not exclude the presence of a plurality of these elements.

Preferably, in the context of this document, the terms "rotor stage" and "variable setting" are used in the sense defined in the prior art. Preferably, the variable pitch timing synchronization ring is a ring called "VSV ring". Preferably, the radial deformation of the ring that the system according to the invention makes it possible to prevent is an "ovalization" of the ring.

Preferably, the compressor is a low pressure compressor. Preferably, the stator stage is one of the first and the third stator stage of the compressor, all of the stages being ordered according to an air flow circulating in the compressor.

According to a preferred embodiment of the invention, the bearing supports are successively and symmetrically fixed on a lateral side of the ring, each of the bearing supports being equidistant from

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- 8 two other bearing supports which are adjacent to each of the bearing supports.

Each plane tangent to this lateral side is preferably essentially orthogonal to the motor axis. A lateral side of the ring is distinguished from the lower and upper sides of the ring which are themselves locally parallel to a surface close to the casing and to which each tangent plane is essentially parallel to the motor axis.

Preferably, the numbers of supports and rolling walls are equal and greater than three, more preferably greater than ten. Optionally, it can be equal to the number of vanes.

Preferably, each of the rolling walls is configured to overcome one and only one of the rolling supports externally and in parallel. The system then comprises a succession of pairs each consisting of a bearing support and a bearing wall arranged circumferentially around the motor axis, and surmounting the housing portion.

The system according to this preferred embodiment allows a good distribution of the radial and circumferential forces on the ring. Each pair contributes to a local prevention of radial detachment of the ring, and these pairs being distributed in a balanced manner and preferably equidistant successively two by two, the ring is radially stable over its entire length.

According to a preferred embodiment of the invention, the system further comprises a plurality of parts, each of the parts being mechanically fixed to one of the rolling walls and comprising a lateral portion extending essentially along a plane intersecting one of the bearing walls, each of the parts being configured to be mechanically fixed to the casing so as to enclose, essentially parallel to the motor axis, a ball of one of the bearing supports

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- 9 between the lateral portion and a lateral side of the ring to which the bearing supports are mechanically fixed.

The system is then configured so that a distance between the ball and the lateral portion is strictly positive and variable when the displacement unit is in action. In particular, the parts are capable of containing the axial displacements of the ring and of the bearing supports which are controlled by the displacement unit.

Advantageously, the parts can be fixed mechanically to the casing, either directly or via a ferrule external to the compressor. Neither the housing and / or the ferrule must be machined to fix the bearing walls to the compressor, which saves time and money. Advantageously, a replacement of a rolling wall in the event of breakage or wear is very easy and requires only a detachment of the part to which the rolling wall is fixed, and a replacement of the entire part and of the rolling wall.

Preferably, each of the parts includes an extension configured to be fixed to a shroud of the compressor. In particular, this extension may coincide with an extension of a metal cap of the compressor.

According to a preferred embodiment of the invention, the rolling walls consist of sectors of a rolling track of an annular shape being configured to completely surround and externally circumferentially overcome the casing. Preferably, the track consists of a tinsel.

Advantageously, a design of a single raceway comprising all the raceways is easier, less costly, and makes it possible to obtain stiffer raceways.

According to a preferred embodiment of the invention, the each of the rolling walls comprises a lower face portion being

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- 10 covered with an anti-wear coating, and configured to accommodate a support and / or a bearing of the upper cap. The lower face is essentially parallel and surmounted by an upper face of each of the rolling walls. The underside is configured to directly face the housing and / or a bearing support.

Advantageously, the anti-wear coating makes it possible to ensure better resistance and a longer duration of use of the system according to the invention. The rolling of the bearing support balls on the bearing walls when the compressor is in use is liable to flake off the latter and reduce their stiffness. The anti-wear coating prevents a phenomenon.

According to an also preferred embodiment of the invention, each of the bearing supports comprises an adjustment screw for modifying a position of each of the bearing supports relative to the ring, along a radial direction perpendicular to the motor axis.

The adjustment screw is preferably a height adjustment screw for the bearing supports. Its arrangement is made possible by the fact that the bearing supports are attached to the ring. Advantageously, the adjusting screw makes it possible to constrain contact between the upper caps of the balls and the rolling walls, during assembly of the system on a compressor. Better centering of the ring relative to the rolling walls is then possible. Another advantage of this adjusting screw is that it is possible to adapt the positions of the bearing supports after using the system so as to compensate for deformation or wear of the ring. Thus, the risks of loss of contact between the balls and the bearing walls are reduced.

According to a particular embodiment of the invention, the ring comprises a system of pads configured to face the housing and / or slide thereon when the displacement unit is in action. However, a ring without skates would not depart from the framework of

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- 11 the invention. In particular, and according to another particular embodiment of the invention, the hole and the ring externally surmount a lower cap of the ball configured to face the casing and / or roll thereon when the displacement unit is in action. Advantageously, the bearing of the lower caps of the balls facing the casing is stronger and more resistant under conditions of use than the aforementioned pad system. Consequently, this particular embodiment allows better control of a space between a lower base of the ring and of the casing, an adaptation of this space being of primary importance to avoid ovalization of the ring. Finally, optionally and for more reliability, the aforementioned skate system can be combined with this other particular embodiment.

According to a preferred embodiment of the invention, the displacement unit comprises at least one jack which is mechanically coupled to the ring.

Such a jack acts as an actuator for moving the ring along an arc, partially axially and circumferentially. The cylinder is preferably a pneumatic cylinder or a hydraulic cylinder or an electric cylinder. It is preferably directly connected to a control unit of the turbomachine.

Preferably, the displacement unit comprises only one such cylinder. Advantageously, the system according to the invention allows the use of a single jack to prevent ovalization of the ring. In particular, the system according to the invention makes it possible to use a displacement unit of a small mass, thus advantageously reducing the mass, the bulk, and the complexity of the compressor.

A displacement unit comprising two jacks coupled at diametrically opposite points of the ring would not, however, depart from the scope of the invention and would allow greater reliability of the compressor, and great stability of the ring on the casing.

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The present invention also provides a compressor for an aircraft turbomachine comprising a system according to the invention. The present invention also provides an aircraft turbomachine comprising such a compressor according to the invention.

All of the preferred embodiments as well as all of the advantages of the system according to the invention transpose mutatis mutandis to the present compressor and to the present aircraft turbomachine. In particular, and preferably, the compressor according to the invention is such that:

the system is a system of variable timing of blades of a stator stage of the compressor;

the ring is fitted circumferentially around a compressor casing, and is mechanically coupled to the blades;

the bearing supports are fixed laterally to the ring, along the ring, and externally surmount in parallel an annular portion of the casing extending circumferentially around the motor axis around which the casing extends;

the rolling walls are mechanically coupled to the casing and externally surmount in parallel the annular portion of the casing, at a fixed distance from the latter.

The compressor according to the invention is preferably a low pressure compressor. A high pressure compressor fitted with the system according to the invention would not, however, depart from the scope of the invention.

Brief description of the figures

Other characteristics and advantages of the present invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended figures among which:

FIG. 1 illustrates a partial three-dimensional schematic view of a compressor of an aircraft turbomachine comprising a

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- 13 variable blade timing system according to one embodiment of the invention;

FIG. 2 illustrates a partial three-dimensional schematic view of a variable blade timing system according to an embodiment of the invention;

FIG. 3 illustrates a two-dimensional section through a casing of a compressor of an aircraft turbomachine to which a variable blade timing system is mechanically coupled according to an embodiment of the invention.

The drawings of the figures are not to scale. Generally, similar elements are denoted by similar references in the figures. In the context of this document, identical or analogous elements may have the same references. In addition, the presence of reference numbers or letters in the drawings cannot be considered as limiting, including when these numbers or letters are indicated in the claims.

Detailed description of particular embodiments of the invention

The present invention is described with particular embodiments and references to figures, but the invention is not limited by these. The drawings or figures described are only schematic and are not limiting.

The elements designated by the references Y, Z, P, E, I and I 'are shown in certain figures by way of illustration in order to quantify and / or visualize properties of embodiments of the invention. In particular, these elements are abstract benchmarks and do not necessarily correspond to concrete material objects. More specifically, the Z axis represents a motor axis along which the stages of a compressor 4 are stacked, and around which extends a casing 41 of the compressor 4. The Y axis designates an arbitrary vector directed radially in the defined direction

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- 14 in the summary of the invention. It is directed perpendicular to the motor axis Z, from the inside to the outside of the housing 41.

FIG. 1 illustrates a compressor 4 of an aircraft turbomachine comprising a system 1 of variable timing of blades 2 of a stator stage of the compressor 4 according to a particular embodiment of the invention. The system includes:

a ring 5 for synchronizing the variable timing of the vanes 2 which is locally helically movable via a displacement unit (not shown) and adjusted around a casing 41, along a circumference of the compressor 4;

a mechanical coupling system 10 of the vanes 2 to the ring 5 comprising a plurality of levers 11, each of the levers 11 being articulated on the one hand with the ring 5, and on the other hand with an end rod 21 of a vanes 2;

a plurality of bearing supports 7 fixed laterally, at regular intervals, on the ring 5, and externally surmounting an annular portion P of the casing 41, this extending circumferentially around the motor axis Z, each bearing supports 7 being set with a ball 8 capable of undergoing a rotational movement on itself during a movement of the ring 5;

a plurality of rolling walls 9 mechanically fixed to the casing 41 by means of sections 6 profiled sectionally in the form of an "L", so that each of the rolling walls 9 externally overcomes both the portion P of the casing 41 and one of the rolling supports 7, the ball 8 of which rests on the rolling wall 9.

The system 1 thus limits any movement and / or deformation of the ring 5 in an arbitrary radial direction Y perpendicular to the motor axis Z, and consequently prevents possible ovalization of the ring 5, while allowing it to follow freely helical displacements

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- 15 controlled by the displacement unit, these being guided and supported by a ball bearing between the bearing supports 7 and the bearing walls 9.

As illustrated in FIG. 2, each ball 8 is arranged in a hole 71 of one of the bearing supports 7. An upper cap 81 of the ball 8 is brought into contact with a portion of lower face 91 of the bearing wall 9, when the latter externally surmounts the bearing support 7 following an assembly E carried out during assembly of the system 1 on the casing 41. The lower face portion 91 is covered with an anti-wear coating to guarantee more high resistance and / or longevity to ball bearings. The bearing support 7 illustrated comprises an adjustment screw 72 to modify its position in height, along the Y axis, relative to the ring 5. Thus, the upper cap 81 of the ball 8 can be more easily constrained at the level of the lower face portion 91 via an adjustment of the adjusting screw, even after using the system 1. The rolling wall 9 is particularly stiff and approximately flat, with a length I of at least 60 mm measured circumferentially. The part 6 is attached circumferentially to the rolling wall 9 and comprises two approximately flat portions 61 and 62. The lateral portion 61 extends essentially along a plane orthogonal to the rolling wall 9, and makes it possible to enclose the rolling support 7 and the ball 8 parallel to the motor axis Z, while allowing to axially contain a displacement of the ring 5 controlled by the displacement unit. The portion 62 is essentially parallel to the rolling wall 9. It is fixed, for example by means of screws, to the housing 41. Furthermore, the ring 5 comprises a system of pads 51 configured to face the housing 41 and / or slide on it when the displacement unit is in action. Such a pad system 51 is nonetheless optional for the system 1 according to the invention as explained in the summary of the invention.

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- 16 Figure 3 illustrates a sectional view of the housing 41 to which the system 1 is mechanically coupled. The section illustrates the elements shown in Figure 2 after performing assembly E and mounting on the housing 41. The length Γ between a center of the ball 8 and one end of the rolling wall 9 is at least 10 mm. A lower cap 82 of the ball 8 faces the casing 41 and is capable of constituting a ball bearing to replace the system of pads 51.

In summary, the present invention relates to a system 1 for variable timing of blades 2 of a stator stage of a compressor 4 of an aircraft turbomachine. The system 1 comprises, in particular, a ring 5 for synchronizing the variable timing of the vanes 2 to which lateral bearing supports 7 are fixed laterally, each of these bearing supports 7 being set with a ball 8 arranged to rest and roll on a rolling wall 9 surmounting it and being configured to be mechanically coupled to a casing 41 of the compressor 4.

The present invention has been described in relation to specific embodiments, which have a purely illustrative value and should not be considered as limiting. In general, it will be obvious to a person skilled in the art that the present invention is not limited to the examples illustrated and / or described above. The invention includes each of the new features and all of their combinations.

Claims (14)

Claims 1. System (1) for variable timing of blades (2) of a stator stage of a compressor (4) of an aircraft turbomachine comprising: a ring (5) for variable timing synchronization of said blades (2) configured to be circumferentially adjusted around a casing (41) of said compressor (4), and to be mechanically coupled to said blades (2); a displacement unit for displacing said ring (5) at least partially circumferentially and / or parallel to a motor axis (Z) around which extends said casing (41); characterized in that it further comprises: a plurality of bearing supports (7) fixed laterally to said ring (5), along said ring (5), each of said bearing supports (7) comprising at least one hole (71) in which a ball (8) is arranged able to undergo a rotational movement on itself relative to said hole (71), an upper cap (81) of said ball (8) surmounting an opening of said hole (71); a plurality of fixed bearing walls (9) for cooperating with the balls (8) of said bearing supports (7); each of said rolling walls (9) being configured to overcome externally and in parallel at least one of said rolling supports (7), so as to allow support and / or rolling of the upper cap (81) of the ball (8) said at least one of said bearing supports (7) on said each of said bearing walls (9); the system (1) being configured to limit movement and / or deformation of said ring (5) in an arbitrary radial direction (Y) perpendicular to said motor axis (Z). BE2018 / 5843 2. System (1) according to the preceding claim, characterized in that said bearing supports (7) are successively fixed symmetrically on a lateral side of said ring (5), each of said bearing supports (7) being equidistant from two others of said bearing supports (7) which are adjacent to each of said bearing supports (7). 3. System (1) according to the preceding claim, characterized in that each of said rolling walls (9) is configured to overcome externally and in parallel one and only one of said rolling supports (7). 4. System (1) according to any one of the preceding claims, characterized in that it further comprises a plurality of parts (6), each of the parts being mechanically fixed to one of said rolling walls (9) and comprising a lateral portion (61) extending essentially along a plane intersecting said one of said rolling walls (9), said each of said parts (6) being configured to be mechanically fixed to said casing (41) so as to be enclosed essentially parallel to said axis motor (Z), a ball (8) of one of said bearing supports (7) between said lateral portion (61) and a lateral side of said ring (5) to which said bearing supports (7) are mechanically fixed. 5. System (1) according to the preceding claim, characterized in that said each of said parts (6) comprises an extension configured to be fixed to a ferrule of said compressor (4). 6. System (1) according to any one of the preceding claims, characterized in that said rolling walls (9) consist of BE2018 / 5843 - 19 of the sectors of a rolling track of an annular shape being configured to completely surround and externally circumferentially overcome said casing (41). 7. System (1) according to any one of the preceding claims, characterized in that said each of said rolling walls (9) comprises a lower face portion (91) being covered with an anti-wear coating and configured to accommodate support and / or rolling of said upper cap (81). 8. System (1) according to any one of the preceding claims, characterized in that said each of said bearing supports (7) comprises an adjustment screw (72) for modifying a position of said each of said bearing supports (7) by relationship to said ring (5) along a radial direction perpendicular to said motor axis (Z). 9. System (1) according to any one of the preceding claims, characterized in that the said ring (5) comprises a system of pads (51) configured to face the said casing (41) and / or slide thereon when the displacement unit is in action. 10. System (1) according to any one of the preceding claims, characterized in that said hole (71) and said ring (5) externally surmount a lower cap (82) of said ball (8) configured to face said casing (41) and / or drive thereon when the displacement unit is in action. 11. System (1) according to any one of the preceding claims, characterized in that said displacement unit comprises at least one jack which is mechanically coupled to said ring (5). BE2018 / 5843 12. Compressor (4) of an aircraft turbomachine comprising a system (1) according to any one of the preceding claims, characterized in that: said system (1) is a variable timing system of vanes (2) of a stator stage of said compressor (4); said ring (5) is adjusted circumferentially around a casing (41) of said compressor (4), and is mechanically coupled to said blades (2); said bearing supports (7) are fixed laterally to said ring (5), along said ring (5), and externally surmount in parallel an annular portion (P) of said casing (41) extending circumferentially around said motor axis ( Z) around which extends said housing (41); said rolling walls (9) are mechanically coupled to said housing (41) and externally surmount said annular portion (P) of said housing (41), at a fixed distance from the latter. 13. Compressor (4) according to the preceding claim characterized in that said compressor (4) is a low pressure compressor. 14. Aircraft turbomachine comprising a compressor (4) according to any one of the two preceding claims.