EP3740658B1 - Turbomachine ring - Google Patents

Description

FIELD OF THE INVENTION

The present invention relates to a turbomachine ring as well as a turbomachine comprising such a ring and a method of repairing such a ring. It may in particular be a compressor or turbine ring of an aircraft engine, single or double flow.

STATE OF PRIOR ART

In many turbomachine compressors, but also in certain turbines, the fixed blades are mounted on sectors forming a crown materializing the air stream: these sectors are then mounted on the stator casing using hook parts 'engaging in notches of a stator support.

However, during operation of the turbomachine, due in particular to the vibrations suffered by the sectors of the ring, the hooks of the sectors rub and wear the notches of the support: we therefore sometimes see erosion on the internal faces of the notches. Naturally, such erosion modifies the chains of dimensions between the parts of the ring, in particular opening gaps and moving parts, which can lead to leaks and cause loss of performance.

Therefore, it is desired to be able to repair these notches without replacing the entire support.

A possible repair option would be to locally refill the notch material, either by thermal spraying, welding or brazing. However, such solutions are difficult to achieve due to the difficulty of accessing the area to be reworked and the geometry of the area to be reworked.

Another possible option would be to attach a hoop type element to each face of the notch to be repaired. However, it is difficult to resinate the complete vein in this way. Indeed, resining leads to excessively significant dimensional dispersions; moreover, the temperature resistance of the resins is not sufficient in the context of an application on a turbomachine. We also know the documents EP 2 613 021 And UK 2,477,825 which offer anti-wear shirts.

There is therefore a real need for a turbomachine ring, as well as a turbomachine comprising such a ring and a method of repairing such a ring, which are devoid, at least in part, of the disadvantages inherent in the aforementioned known methods.

PRESENTATION OF THE INVENTION

The present invention relates to a turbomachine ring according to claim 1. This ring comprises a support, essentially cylindrical, comprising a front surface in which a notch is made, one or more sectors forming a crown configured to materialize a section of air stream , each sector comprising a hook part projecting towards the support and engaging in the notch of the support, and an anti-wear device having a U-shaped part, provided in the notch of the support and pressed at least against the radially external surface of the notch, and a tongue part, continuously extending the U-shaped part, pressed and fixed against the front surface of the support.

Thanks to such an anti-wear device, it is possible to easily and effectively repair a worn support notch. It is also possible to install such an anti-wear device from the outset in order to facilitate maintenance of the turbomachine. Indeed, thanks to such an anti-wear device, in the event of friction or vibration between the sector and the support, the notch of the support is protected, only the anti-wear device wearing out if necessary. However, the anti-wear device can be easily replaced, which drastically reduces repair time and costs.

In addition, thanks to the tongue part plated and fixed against the front surface of the support, it is possible to effectively maintain the anti-wear device in the plated position within the notch while providing increased accessibility allowing fixing and easy removal of the anti-wear device.

Fixing the anti-wear device on the support also makes it possible to simplify the nomenclature of the parts of the turbomachine and the logistics associated with maintenance: in fact, this makes it possible to avoid assigning an individual reference to the anti-wear device .

In certain embodiments, the U-shaped part of the anti-wear device is under elastic stress. This ensures permanent plating of the U-shaped part against the radially external surface of the notch.

In certain embodiments, the radially internal wall of the U-shaped part of the anti-wear device forms, at rest, a first angle of between 5° and 20°, preferably between 10° and 15°, with the direction of the radially outer wall of the U-shaped part. In other words, such an angle appears when the anti-wear device is not inserted into the notch, for example before repairing the support or after its extraction. Such an angle is measured in an axial plane. It makes it possible to generate the elastic stress mentioned above when the anti-wear device is placed in the notch.

In some embodiments, the tongue portion of the anti-wear device is under elastic stress. This makes it possible to return the U-shaped part of the anti-wear device towards the bottom of the notch, thus stabilizing its position.

In certain embodiments, the tongue part of the anti-wear device forms, at rest, a second angle of between 5° and 20°, preferably between 10° and 15°, with the direction orthogonal to the radially outer wall of the U-shaped part. In other words, such an angle appears when the anti-wear device is not inserted into the notch, for example before repairing the support or after its extraction. Such an angle is measured in an axial plane. It makes it possible to generate the elastic stress mentioned above when the anti-wear device is placed in the notch.

In certain embodiments, the tongue part of the anti-wear device is, at rest, substantially orthogonal to the radially internal wall of the U-shaped part.

In some embodiments, the tongue portion of the anti-wear device continuously extends the U-shaped portion radially inward. Thus, the tab part is fixed on the radially inner region of the front surface of the support. This facilitates access to the anti-wear device from inside the ring, helps to press the U-shaped portion of the anti-wear device against the radially outer surface of the notch, and protects the front surface of the support from friction with ring sector.

In certain embodiments, a space is left between the U-shaped part of the anti-wear device and the bottom of the notch in the support. This space allows a tool to be slipped between the anti-wear device and the bottom of the notch in order to facilitate the extraction of the anti-wear device.

In certain embodiments, a space is left between the U-shaped part of the anti-wear device and at least a portion of the radially internal surface of the notch of the support. This reinforces the pressing of the U-shaped part of the anti-wear device against the radially external surface of the notch of the support.

In certain embodiments, these fixing points may in particular have a diameter less than 1 mm, or even 0.5 mm. This facilitates the attachment of the anti-wear device but also its removal, such attachment points being easy to break.

In certain embodiments, the fixing points are distributed regularly along the tongue portion of the anti-wear device, particularly in the circumferential direction.

In certain embodiments, at least an angular distance of 15°, preferably 20°, separates two attachment points. Moving the fixing points further apart makes it easier to break the fixing points and therefore remove the anti-wear device.

In some embodiments, the tab portion of the anti-wear device is attached to the front surface of the support by welding. These may in particular be welding points by capacitor discharge. The weld in fact resists the high operating temperatures of the turbomachine and only causes small dimensional dispersions.

In certain embodiments, the anti-wear device is separable from the support under the effect of a manual tearing force. This provides a light tearing force for an operator, which allows easy and rapid maintenance. In particular, it is possible to separate the anti-wear device by simple leverage by inserting a tool, such as a screwdriver tip for example, between the anti-wear device and the support.

In certain embodiments, the thickness of the anti-wear device is between 0.1 mm and 1 mm, preferably between 0.2 mm and 0.6 mm. This is compatible with the usual size of the notches of the turbomachine ring supports.

In certain embodiments, the thickness of the anti-wear device is scalable. Indeed, it is preferable to reserve a greater thickness in the areas of the notch against which the sector is likely to rub and a lower thickness in the other areas to reduce the probability of unexpected contact with the sector. Thus, in particular, the thickness of the radially internal wall of the U-shaped part of the anti-wear device may be less than the thickness of the radially external wall of the U-shaped part.

In certain embodiments, the anti-wear device has a hardness lower than that of the support. This allows preferential wear of the anti-wear device relative to the support, thus preserving the support.

In some embodiments, the anti-wear device has a lower hardness than the sector hook. This allows preferential wear of the anti-wear device relative to the support hook, thus preserving the support hook.

In certain embodiments, the anti-wear device is made of Inconel.

In certain embodiments, the anti-wear device comprises a base element taking the form of a profile, preferably of the foil type. This foil is preferably metallic. This basic element may have any number of characteristics from those mentioned above.

In certain embodiments, the anti-wear device further comprises an additional U-shaped element provided inside the U-shaped part of the base element. This additional element may have any number of characteristics among those mentioned above. It is thus possible to dissociate certain functions of the basic element and the additional element and/or offer differentiated behavior with respect to the support on the one hand and the sector hook on the other hand. In particular, the base element can provide the mechanical functions of positioning and fixing the anti-wear device while the additional element can ensure the preferential wear functions therefore protecting the sector hook and the notch of the support.

In certain embodiments, the additional element takes the form of a profile, preferably of the foil type, preferably metallic, distinct from the base element. The additional element can therefore be manufactured independently of the basic element and then assembled with the latter.

In certain embodiments, the additional element is under elastic stress. This makes it possible to press the additional element against the radially external surface of the U-shaped part of the base element.

In certain embodiments, the additional element takes the form of a coating deposited on the base element. The anti-wear device is thus in one piece.

In certain embodiments, the base element and the additional element form two layers of the same profile, preferably of the foil type. The anti-wear device is thus in one piece.

In certain embodiments, the thickness of the additional element is between 0.1 and 0.4 mm, preferably between 0.1 and 0.3 mm.

In certain embodiments, the additional element has a lower hardness than that of the base element. This allows preferential wear of the additional element relative to the support, the basic element retaining superior mechanical strength.

In certain embodiments, the additional element is made of an alloy based on nickel and/or cobalt. It can be provided with an anti-wear coating, for example a deposit based on nickel and/or chromium.

In certain embodiments, the anti-wear device is sectorized. Each sector can in particular extend over an angular sector of between 30 and 60°.

In certain embodiments, the sector hook is pressed against the radially external surface of the anti-wear device. It is understood that this is achieved at least in operation.

In some embodiments, the ring is part of a compressor, preferably a high pressure compressor. It could also be a turbine ring. It can just as easily be integrated into a single or double flow turbomachine.

The present presentation also relates to a turbomachine, comprising a turbomachine ring according to any one of the preceding embodiments.

The present invention also relates to a method of repairing a turbomachine ring according to claim 10, the turbomachine ring comprising a support, essentially cylindrical, comprising a front surface in which a notch is made, said notch having been at least partially eroded, and one or more sectors forming a crown configured to materialize a section of air vein, each sector comprising a hook part projecting towards the support and engaging in the notch of the support, the repair method comprising the following steps: machining the internal walls of the notch; installation of an anti-wear device, having a U-shaped part and a tongue part, in the notch thus machined; fixing the tongue part of the anti-wear device to the front surface of the support, the tongue part being fixed to the front surface of the support by fixing points.

In certain embodiments, the anti-wear device conforms to any of the embodiments presented above.

In this presentation, the terms “axial”, “radial”, “tangential”, “proximal”, “distal” and their derivatives are defined in relation to the main axis of the turbomachine; “axial plane” means a plane passing through the main axis of the turbomachine and “radial plane” means a plane perpendicular to this main axis; a “frontal” surface is part of a radial plane; finally, the terms “upstream” and “downstream” are defined in relation to the circulation of air in the turbomachine.

The aforementioned characteristics and advantages, as well as others, will appear on reading the detailed description which follows, of examples of embodiment of the turbomachine ring and the method proposed. This detailed description refers to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are schematic and aim above all to illustrate the principles of the invention.

• La FIG 1 est un plan en coupe d'une turbomachine selon l'exposé.
• La FIG 2 est une vue en coupe d'un premier exemple d'anneau de turbomachine.
• La FIG 3 est un agrandissement de la zone III de la FIG 2.
• La FIG 4 est une vue en coupe du dispositif anti-usure du premier exemple.
• La FIG 5 illustre un deuxième exemple de dispositif anti-usure.

In these drawings, from one figure (FIG) to another, identical elements (or parts of elements) are identified by the same reference signs. In addition, elements (or parts of elements) belonging to different embodiments but having a similar function are identified in the figures by numerical references incremented by 100, 200, etc.

• There FIG 1 is a sectional plan of a turbomachine according to the presentation.
• There FIG 2 is a sectional view of a first example of a turbomachine ring.
• There FIG 3 is an expansion of zone III of the FIG 2 .
• There FIG 4 is a sectional view of the anti-wear device of the first example.
• There FIG 5 illustrates a second example of an anti-wear device.

DETAILED DESCRIPTION OF EXAMPLE(S) OF PRODUCTION

In order to make the presentation more concrete, examples of turbomachine rings are described in detail below, with reference to the appended drawings. It is recalled that the invention is not limited to these examples.

There FIG 1 represents, in section along a vertical plane passing through its main axis A, a single flow turbojet 1 according to the presentation. It comprises, from upstream to downstream according to the circulation of the air flow, a low pressure compressor 3, a high pressure compressor 4, a combustion chamber 5, a high pressure turbine 6, and a low pressure turbine 7.

There FIG 2 illustrates a portion of the stator of the high pressure compressor 4. In this figure, two compressor rings 30 according to a first embodiment are visible. Each compressor ring 30 comprises an upstream ring support 31m and a downstream ring support 31v, generally cylindrical and forming an integral part of the compressor casing 4: they each form a vein wall facing a bladed wheel. Each compressor ring 30 further comprises a crown of ring sectors 32 fixed on the ring supports 31m, 31v: they complete the air stream wall of compressor 4 and carry fixed vanes 32a.

Each ring sector 32 is fixed on the ring supports 31m, 31v using hooking devices 33m and 33v provided at each axial end of the ring sector 32.

More precisely, each ring sector 32 comprises at each of its axial ends a hook 34 extending towards the adjacent support 31m, 31v and penetrating a notch 35 of the support 31m, 31v.

As is best visible on the FIG 3 , the notch 35 is made in the front surface 36 of each support 31m, 31v: it extends continuously in the circumferential direction; its radially outer 35s and radially inner 35p walls are parallel.

An anti-wear device 40 is placed in this notch 35. The anti-wear device 40, visible on the FIG 4 in its initial state at rest, comprises a U-shaped part 41 and a tongue part 42. The anti-wear device 40 is an arcuate profile extending continuously and invariantly in the circumferential direction: on the FIG 4 , it is shown in section along a transverse plane, that is to say an axial plane in the frame of reference of the turbomachine 1. In the present example, the anti-wear device 40 is sectorized, each sector extending over a arc of the same length; however, in other examples it could be completely annular, split or not. In the present example, the anti-wear device 40 is made of an alloy based on nickel and/or cobalt provided with an anti-wear coating: it has a lower hardness both than the support 31m, 31v and the hook 34 of sector 32.

The U-shaped part 41 comprises a radially outer wall 41d, a bottom wall 41f and a radially inner wall 41p arranged substantially in a U shape relative to each other. More precisely, the bottom wall 41f extends the radially outer wall 41d orthogonally. On the other hand, the radially internal wall, extending the bottom wall 41f, forms a non-zero angle A with respect to the direction of the radially external wall 41d, that is to say the axial direction. In the present example, this angle A is approximately 12°.

The tongue part 42 comprises for its part a single wall extending the radially internal wall 41p of the U-shaped part 41: it forms an angle µ with respect to the direction normal to the radially external wall 41d, that is to say relative to the radial direction. In this example, this angle µ is approximately 12°.

The U-shaped part 41 is engaged in the notch 35 while the tongue part 42 is pressed and fixed against the radially internal zone 36a of the front surface 36 using welding points 37 produced by capacitor discharge. As the distance between the ends of the radially outer 41d and radially inner 41p walls of the U-shaped part 41 of the anti-wear device 40 is greater than the width of the notch 35, the U-shaped part 41 is held under elastic stress within of the notch 35 and its radially outer wall 41d is elastically pressed against the radially outer surface 35d of the notch 35. In addition, the lengths of the radially outer 41d and radially inner 41p walls of the U-shaped part 41 of the anti- wear 40 are less than the depth of the notch 35 so that a space 38 remains between the bottom wall 41f of the U-shaped part 41 and the bottom 35f of the notch 35.

We then note that the hook 34 of the sector 32 enters the notch 35 protected by the anti-wear device 40 and finds itself in a position pressed against the radially external wall 41d of the U-shaped part 41 of the anti-wear device 40 during the operation of the turbomachine 1, a space being left between the hook 34 and the bottom walls 41f and radially inner walls 41p of the U-shaped part 41 of the anti-wear device 40.

An example of a turbomachine repair method according to the presentation will now be described. Its purpose is to repair a turbomachine 1 in which the notch 35 of one or more supports 31m, 31v of the high pressure compressor 4 has been worn and damaged following the friction of the hook 34 of a sector 32 in the latter. Concretely, in such a worn notch, the dimensions of the notch as well as the surface condition of its internal walls are degraded.

The repair process then includes a step of machining the internal walls of the worn notch to a sufficient depth to eliminate the defects and smooth the internal walls so as to obtain the original dimensions to a specific setback, for example 0.2 mm or 0.4 mm.

An anti-wear device 40 as described above, and whose thickness of the walls of the U-shaped part corresponds to the depth of this determined recess, is then inserted into the notch 35 thus machined in order to restore its initial dimensions .

The tongue part 42 of the anti-wear device 40 is then fixed on the radially internal zone 36a of the front surface 36 by welding points 37 produced by capacitor discharge.

The compressor ring 30 is thus repaired.

Once the anti-wear device 40 is thus installed, the hook 34 of the sector 32 wears the anti-wear device 40 but no longer damages the notch 35 of the support 31m, 31v.

Therefore, if the anti-wear device 40 reaches an excessively high level of wear, it is sufficient to remove it and replace it with a new anti-wear device 40 to repair the compressor ring 30. This can be done very easily by inserting a tool into the space 38 located between the anti-wear device 40 and the bottom 35f of the notch 35 and by levering to break the welding points 37 step by step. The new anti-wear device 40 can then be placed in the notch 35 and fixed on the front surface 36 in place of the worn anti-wear device 40.

There FIG 5 illustrates a second example of a turbomachine ring 130. This second example is entirely similar to the first example except that the anti-wear device 140 is different.

In this second example, the anti-wear device 140 comprises a base element 149 and an additional element 159. The base element 149 is shaped in a manner entirely similar to the anti-wear device 40 of the first example except is that its thickness is lower.

The additional element 159 is an arcuate profile extending continuously and invariantly in the circumferential direction: on the FIG 5 , it is represented in section along a transverse plane, that is to say an axial plane in the reference frame of the turbomachine. It takes a U shape complementary to the U-shaped part 141 of the base element 149. Thus, at rest, the radially internal wall 151p of the additional element 159 also forms an angle λ with the direction of its radially external wall 151d, that is to say with the axial direction, such that the additional element is maintained in elastic compression within the base element 149 when the latter is engaged in the notch 135 of the support 131v.

In the present example, the base element 149 of the anti-wear device 140 is made of an alloy based on nickel and/or cobalt while the additional element 159 is made of an alloy based on nickel and/or cobalt. cobalt: the additional element 159 has a lower hardness than both the basic element 159 and the hook 134 of sector 132.

Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the different illustrated/mentioned embodiments can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

It is also obvious that all the characteristics described with reference to a process can be transposed, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device can be transposed, alone or in combination, to a process.

Claims (10)

1. A turbomachine ring, comprising

   an essentially cylindrical support (31v), provided to extend around an axial direction (A) of the turbomachine, the support (31v) including a frontal surface (36) wherein a notch (35) is formed, the notch (35) comprising a radially internal surface (35i), a bottom (35f) and a radially external surface (35d),

   one or more sectors (32) forming an annulus configured to embody a segment of air stream, each sector (32) comprising a hook portion (34) protruding in the direction of the support (31v) and engaging in the notch (35) of the support (31v), and

   an anti-wear device (40) having a U shaped portion (41), provided in the notch (35) of the support (31v) and pressed at least against the radially external surface (35d) of the notch (35), and a tab portion (42), continuously extending the U shaped portion (41), pressed and fastened against the frontal surface (36) of the support (31v),

   characterized in that the tab portion (42) of the anti-wear device is fastened to the frontal surface (36) of the support (31v) by fastening points (37),

   a space (38) is left between the U shaped portion (41) of the anti-wear device (40) and the bottom (35f) of the notch (35) of the support (31v), and

   the U shaped portion (41) of the anti-wear device (40) is under elastic constraint.
2. The ring according to claim 1 or 2, wherein the tab portion (42) of the anti-wear device (40) is under elastic constraint.
3. The ring according to claim 1 or 2, wherein the tab portion (42) of the anti-wear device (40) is fastened to the frontal surface (36) of the support (31v) by welding points (37).
4. The ring according to claim 3, wherein the welding points (37) are of the type obtained by capacitor discharge.
5. The ring according to any one of claims 1 to 4, wherein the thickness of the anti-wear device (40) is comprised between 0.1 mm and 1 mm, preferably between 0.2 mm and 0.6 mm.
6. The ring according to any one of claims 1 to 5, wherein the anti-wear device (40) has a hardness less than that of the support (31v) and less than that of the hook (34) of the sector (32).
7. The ring according to any one of claims 1 to 6, wherein the anti-wear device (140) comprises a base element (149) taking the form of a section having a U shaped portion (141) and a tab portion (142), and an additional element (159), in the shape of a U, provided in the interior of the U shaped portion (141) of the base element (149),
   wherein the additional element (159) has a hardness less than that of the base element (149).
8. The ring according to claim 7, wherein the additional element (159) takes the form of a section distinct from the base element (149), or of a layer deposited on the base element (149), or even of a layer forming the same section with the base element (149).
9. A turbomachine, comprising a turbomachine ring (30) according to any one of the preceding claims.
10. A method for repairing a turbomachine ring, the turbomachine ring (30) comprising

    an essentially cylindrical support (31v), including a frontal surface (36) wherein a notch (35) is formed, said notch (35) having been at least partially eroded, and

    one or more sectors (32) forming an annulus configured to embody a segment of air stream, each sector (32) comprising a hook portion (34) protruding in the direction of the support (31v) and engaging in the notch (35) of the support (31v),

    the repair method comprising the following steps:

    machining the internal walls of the notch (35);

    placing an anti-wear device (40) having a U shaped portion (41) and a tab portion (42), into the notch (35) thus machined, a space (38) being left between the U shaped portion (41) of the anti-wear device (40) and the bottom (35f) of the notch (35) of the support (31v), and the U shaped portion (41) of the anti-wear device (40) being under elastic constraint;

    fastening of the tab portion (42) of the anti-wear device (40) to the frontal surface (36) of the support (35).

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