FR3115342A1 - EXTENDABLE SEALING DEVICE, PARTICULARLY FOR A VARIABLE PITCH BLADE BLOWER - Google Patents

Abstract

The invention relates to an expandable sealing device (45) comprising: - a sealing cap (47) provided with a screw passage hole (53), - a compression screw (52) inserted at the inside the screw passage hole (53), - a deformable washer (58) having in the undeformed state a radial dimension (D1) less than or equal to a radial dimension (D2) of the sealing plug (47), - a mobile compression washer (59), and - a screwing nut (60) intended to cooperate with a threaded end of the compression screw (52), in such a way that a resultant tightening force (F3) of the compression screw (52) with the screwing nut (60) is able to cause a displacement of the mobile compression washer (59) causing a radial deformation of the deformable washer (58) having in the deformed state a radial dimension (D1) greater than the radial dimension (D2) of the sealing plug (47). Picture 9a

Description

EXTENDABLE SEALING DEVICE, PARTICULARLY FOR A VARIABLE PITCH BLADE BLOWER

The present invention relates to an extendable sealing device, in particular for a fan with variable pitch blades.

An aircraft turbomachine conventionally comprises from upstream to downstream, with reference to the flow of gases in the turbomachine, a fan, one or more compressors, an annular combustion chamber, one or more turbines and a combustion gas exhaust pipe.

FIGS. 1a and 1b show a fan 1 comprising a ring 2 having an axis X. Vanes 3 extend radially outwards from ring 2 along their axis Y. Vanes 3 are regularly distributed angularly along a circumference of the ring 2. The blades 3 are of the variable pitch type, that is to say they can be wedged in a predetermined position around their respective Y axis in order to adapt and optimize this position depending in particular on the speed of the turbomachine.

The document FR2992347 describes for example a ring fitted with variable-pitch vanes intended to be used in a turbomachine propelling an aircraft. The one-piece type ring incorporates a plurality of pivots allowing rotation of the blades. A vane is received in a groove formed in a corresponding pivot. A platform is inserted into the pivot from the outside with a bearing assembly.

In practice, the vanes 3 can be moved over more than 90° around their Y axis, from a "flag" position in which one vane is substantially aligned with the X axis as illustrated by FIG. 1a, and a "reverse" position in which a vane is capable of generating an airflow that is reversed with respect to the direction of flow of the airflow in the turbomachine, as illustrated by the Figure 1b.

In order to determine an optimal "inverter" position, it is known to use a system capable of locking different "inverter" positions during tests of the fan. This locking system is integrated into a turbomachine test bench comprising numerous measurement equipment in order to be able to identify the best position. This equipment is bulky and it can be problematic to mount it in a fan module comprising a system for angular setting of the fan blades. It is indeed important that the variable pitch system does not interfere with the measurements taken, in particular of the behavior of the fan blades, and that this system can withstand the thrust forces in "inverter" operation.

Devices have been proposed to solve this problem. Thus, the document filed under the number FR2005891 teaches a simplified method of fixing the blades. According to this architecture, a pivot is arranged between two annular elements fixed to each other. One of the annular elements has windows for access to fixing members ensuring the fixing of a retaining flange of a pivot on the opposite annular element.

However, the presence of access windows to the fixing devices creates a problem of internal tightness to the annular elements, insofar as air can enter the system via the functional clearances of the pivot and exit through the windows of access without being controlled.

A simple solution consists in sealing the openings of the access windows using a silicone-based hardening paste, for example an RTV type paste. However, the duration of implementation of such a solution is long due to the drying time of the paste. There is also a limit in the size of a plug that can be made from hardening paste. In addition, accessibility to the fixing member is made difficult following the positioning of the plug, which must be destroyed before being able to modify the angular position of a blade.

The invention aims to remedy the aforementioned drawbacks by proposing an extendable sealing device comprising:
- a sealing plug with a screw hole,
- a compression screw inserted inside the screw passage hole,
- a deformable washer having, in the undeformed state, a radial dimension less than or equal to a radial dimension of the sealing plug,
- a movable compression washer, and
- a screwing nut intended to cooperate with a threaded end of the compression screw,
in such a way that a force resulting from tightening the compression screw with the screwing nut is capable of causing a displacement of the mobile compression washer causing a radial deformation of the deformable washer having in the deformed state a radial dimension greater than the radial dimension of the sealing plug.

The invention thus makes it possible to effectively seal a part such as an annular element of an annular fan ring. The invention is easily removable, which facilitates access to the system for adjusting the variable pitch of the fan blades.

According to one embodiment of the invention, the deformable washer and the movable compression washer are mounted on the compression screw between an end face of the sealing plug and the screwing nut.

According to one embodiment of the invention, the sealing plug comprises a radial shoulder located on the opposite side of the deformable washer.

According to one embodiment of the invention, the radial shoulder carries a seal.

According to one embodiment of the invention, the sealing plug is made of a rigid material.

According to one embodiment of the invention, the deformable washer is made of an elastic material, such as an elastomeric material.

According to one embodiment of the invention, the compression screw has a shouldered head.

According to one embodiment of the invention, the compression screw has a countersunk head.

According to one embodiment of the invention, the mobile compression washer has a balancing weight function.

The invention also relates to an assembly comprising:
- a part provided with a through opening opening on the one hand into a first end face of the part and on the other hand into a second end face of the part, and
- an expandable sealing device as previously defined arranged inside the through opening of the part.

According to one embodiment of the invention, the part is an annular element of a fan ring.

According to one embodiment of the invention, the through opening is a window formed in a wall of the annular element, said window allowing access to at least one fixing member ensuring the fixing of a pivot flange.

According to one embodiment of the invention, the compression screw is capable of ensuring the tightening of a pivot flange providing angular retention of a pivot secured to a blade.

The present invention will be better understood and other characteristics and advantages will become apparent on reading the following detailed description comprising embodiments given by way of illustration with reference to the appended figures, presented by way of non-limiting examples, which may be used to complete the understanding of the present invention and the presentation of its realization and, if necessary, contribute to its definition, on which:

[Fig. 1b] Figures 1a and 1b, already described, show a turbomachine fan fitted with variable-pitch vanes respectively in a "flag" position and an "inverter"position;

FIG. 2 is a perspective view of a fan according to the invention for an aircraft turbomachine test bed;

Figure 3 is a schematic sectional view illustrating the tightening of a blade pivot by means of a flange integrated in the fan according to the invention;

Figure 4 is a partial perspective view of a fan according to the invention provided with a pivot inserted inside a housing of an annular element and maintained in its angular position by means of a pivot flange ;

Figure 5 is a perspective view of a modular assembly comprising a pivot and platforms held around the pivot by means of an elastic ring;

Figure 6 is a partial perspective view of a fan according to the invention provided with an upstream annular element shown transparently and provided with access windows to the pivot flange fixing members;

[Fig. 7b] FIGS. 7a and 7b are respectively front and side views of an annular element of a turbomachine fan provided with windows for access to fastening members intended to be blocked by sealing devices that can be extended according to invention;

Figure 8 is a sectional view of an expandable sealing device according to the invention;

Figure 9a is a sectional view of an expandable sealing device according to the invention arranged inside a window formed in the annular element of Figures 7a and 7b with a deformable washer in the undeformed state ;

Figure 9b is a sectional view of an expandable sealing device according to the invention arranged inside a window formed in the annular element of Figures 7a and 7b with a deformable washer in the deformed state.

It should be noted that, in FIGS. 2 and following, the structural and/or functional elements common to the different embodiments may have the same references. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

FIG. 2 shows a fan 10 for an aircraft turbomachine test bed comprising a ring 11 having an axis X and a plurality of blades 12. The blades 12 extend radially outwards from the ring 11 along their axis Y. The vanes 12 are distributed angularly in a regular manner along a circumference of the ring 11.

A blade 12 is integral with a corresponding pivot 13 shown in FIG. 4. To this end, a blade 12 has a blade root 15 inserted in a groove 16 of complementary shape provided in a corresponding pivot 13. The complementary shapes of the blade root 15 and of the groove 16 may in particular be dovetail, hammer-type, or fir-tree shapes. Any other shape suitable for the application may be used.

The ring 11 comprises two coaxial annular elements 18.1, 18.2 fixed to one another and defining between them housings 17 for mounting the pivots 13 visible in FIG. air generated by the fan in operation, an upstream annular element 18.1 and a downstream annular element 18.2. Thus, a portion of a housing 17 is delimited by the upstream annular element 18.1 and a complementary portion of the housing 17 is delimited by the downstream annular element 18.2.

In addition, as can be seen in particular in Figure 3, a flange 19, called "pivot flange", ensures a clamping of a pivot 13 between said flange 19 and the downstream annular element 18.2, so as to immobilize the blade 12 in a desired angular position for a test of the fan 10. For this purpose, the pivot flange 19 comprises a clamping portion 20 cooperating with an annular end section 25 of the pivot 13 and two fastening interfaces 21. A fixing interface 21 is arranged at one end of the flange 19. A fixing interface 21 comprises a hole for passage of a fixing member 23, such as a screw visible in FIG. 4, cooperating with a threaded hole 24 made in the downstream annular element 18.2. Alternatively, the hole 24 is a smooth hole and the screw 23 cooperates with a nut. The flange 19 thus forms a movable clamping jaw with respect to the downstream annular element 18.2 which is fixed.

Furthermore, a pivot 13 has a generally cylindrical shape. When the clamp 19 is loosened, a pivot 13 allows a blade 12 to rotate around its axis Y relative to the annular elements 18.1, 18.2 so as to be able to select the desired angular position of the blade 12 for a test of the fan 10. A pivot 13 thus allows the blade 12 to be able to rotate around its axis Y independently of the annular elements 18.1, 18.2. It is thus possible to position the blade 12 in all possible angular settings along 360 degrees. Once flange 19 is locked, pivot 13 is held in the desired angular position for testing fan 10.

As can be seen in Figure 4, a pivot 13 has a face 26 resting on a portion of the annular elements 18.1, 18.2 so as to ensure radial retention of the pivot 13. In this case, the face 26 of the pivot 13 bearing against a portion of the annular elements 18.1, 18.2 is constituted by an internal face of a groove 28 bearing against a face of an annular collar 29. The annular collar 29 comes from a face of a housing 17 of the annular elements 18.1, 18.2. The annular flange 29 penetrates inside the groove 28 formed in the pivot 13.

As can be seen in Figures 2 and 6, two platforms 31 are arranged on either side of a corresponding blade 12. The platforms 31 cover one end of the pivot 13. A platform 31 has an outer face 37 flush with an outer face of the annular elements 18.1, 18.2 in order to ensure the aerodynamics of the fan 10.

Seals 40 visible in particular in Figures 5 and 6, are each disposed between a face of a blade 12 and a corresponding platform 31. The air seals 40 are designed to be compressed in operation between the blade 12 and the corresponding platform 31. The seals 40 are also compressed by the ring 41. The seals 40 thus ensure the tightness of the assembly by pushing the platform 31 against the ring 11 via a support on the blade 12. A vein profile is thus obtained optimum due to the continuity of the surface between the annular elements 18.1, 18.2 and the blade 12 ensured by the platforms 31 and the seals 40 in contact with the adjacent parts.

Advantageously, as can be seen in Figures 5 and 6, the platforms 31 are held against a corresponding pivot 13 by means of an elastic ring 41, of the circlip type, so as to obtain a manipulable and transportable assembly. Such an assembly thus makes it possible to facilitate the assembly and disassembly of a pivot 13 and of the associated blade 12.

A pivot flange 19 is arranged axially between the upstream annular element 18.1 and the downstream annular element 18.2. The upstream annular element 18.1 has at least one window 43 for access to at least one fixing member 23 ensuring the fixing of the flange 19 on the downstream annular element 18.2, as shown in FIG. 6. A window 43 is constituted by a through opening formed in the upstream annular element 18.1. The through opening 43 allows the passage of a tool intended to cooperate with an imprint of the fasteners 23. A window 43 may be sized to allow access to two adjacent fasteners 23 used for fastening two flanges of pivot 19 adjacent.

As can be seen in Figures 7a and 7b, the through opening 43 opens axially on the one hand in a first end face 44.1 of the annular element 18.1 and on the other hand in a second end face 44.2 of the annular element 18.1.

In order to seal the upstream annular element 18.1, an expandable sealing device 45 shown in Figures 8, 9a, and 9b is used.

This extensible sealing device 45 includes a sealing plug 47 intended to be placed inside the through opening 43 of the annular element 18.1. The sealing plug 47 has a shape complementary to the through opening 43, here of oblong shape. Thus, the sealing plug 47 has, except for fitting clearance, radial and axial dimensions which correspond to those of the through-opening 43. In the case where the through-opening 43 and the sealing plug 47 have a cylindrical shape, their radial dimension corresponds to a diameter.

The sealing plug 47 has a radial shoulder 48 intended to bear against the end face 44.1. The radial shoulder 48 may carry a seal 49 intended to be compressed between said radial shoulder 48 of the sealing plug 47 and the end face 44.1 of the annular element 18.1.

The sealing plug 47 is preferably made of a rigid material, such as a plastic or metallic material. Its dimensions therefore do not vary when using the sealing device 45.

A compression screw 52 is inserted inside a screw passage hole 53 formed in the sealing plug 47. The compression screw 52 is provided with a recess 54 intended to cooperate with a tool 56, such as than a screwdriver (see figure 9b). In this case, the screw head 55 is a shouldered head. Alternatively, the compression screw 52 has a countersunk head to improve the aerodynamics of the assembly. The head of the compression screw 52 can then cooperate with a housing made in the sealing plug 47 so that the external end face of the screw 52 is flush with the corresponding end face of the sealing plug 47. In addition, a countersunk screw improves the centering of a deformable washer 58 described in more detail below.

The compression screw 52 carries the deformable washer 58. The deformable washer 58 may have an annular shape or any other shape adapted to the shape of the through opening 43. The deformable washer 58 has an internal diameter substantially equal to the external diameter of the compression screw 52. The deformable washer 58 is made of an elastic material, such as an elastomeric material. As illustrated by FIG. 9a, in the undeformed state, the deformable washer 58 has a radial dimension D1, in particular an external diameter, equal to or less than a radial dimension D2 of the sealing plug 47, in particular an external diameter of the sealing plug 47. The radial dimension D1 of the deformable washer 58 is therefore also less than or equal to the diameter of the through opening 43 (which corresponds to that of the sealing plug 47).

Compression screw 52 also carries a mobile compression washer 59 resting against a screwing nut 60. Mobile compression washer 59 has an annular shape of radial orientation. The mobile compression washer 59 may have an internal diameter substantially equal to the external diameter of the compression screw 52. The washer 59 is mobile in translation along the compression screw 52 in order to be able to compress the deformable washer 58. The mobile washer of compression 59 is advantageously made of a rigid material, such as a metallic material.

The screw nut 60 cooperates with a threaded end of the compression screw 52.

The deformable washer 58 and the mobile compression washer 59 are arranged between an end face 62 of the sealing plug 47, in particular the face opposite the shoulder 48, and the screwing nut 60. As a variant, the assembly may be reversed, that is to say that the deformable washer 58 and the mobile compression washer 59 may be arranged between the end face 62 of the sealing plug 47 and the screw head 55, the nut of screwing 60 then being located on the shoulder 48 side.

As shown in Figure 9a, to mount the sealing device 45, the latter consisting of the assembly "sealing plug 47 - compression screw 52 - deformable washer 58 - movable compression washer 59 - nut 60" screw is inserted inside the through opening 43 according to the assembly arrow F1. This insertion is possible insofar as the sealing plug 47 has a shape complementary to the through opening 43 and where the deformable washer 58 in the undeformed state does not interfere with the internal diameter of the through opening 43 .

As illustrated by FIG. 9b, once the sealing device 45 has been placed inside the through opening 43, a human operator or a robot can screw the compression screw 52 using a tool 56 adapted by application of a tightening torque represented by the arrow F2. A resultant force of tightening the compression screw 52 with the screwing nut 60 (represented by the arrow F3) causes a displacement of the mobile compression washer 59 causing a radial deformation of the deformable washer 58 having in the deformed state a radial dimension D1 greater than that of the sealing plug 47 (and therefore than that of the through opening 43).

Due to this resultant clamping force, the deformable washer 58 is compressed between the end face 62 of the sealing plug 47 and the mobile compression washer 59. The deformable washer 58 then presses against the end face 44.2 of the annular element 18.1 so as to ensure its tightness.

When it is necessary to modify an angular orientation of the blades 12 during a test, the dismantling of the sealing plug 47 can be carried out easily by unscrewing the compression screw 52 so as to eliminate the resulting tightening force. The deformable washer 58 which is no longer subjected to a compressive force then returns to the undeformed state. Its diameter D1 then becoming less than or equal to that of the through-opening 43, it is possible to remove the sealing device 45 with respect to the through-opening 43 without difficulty.

The operator or the robot will then have access to the fasteners 23 to be able to loosen the pivot flange 19. The operator or the robot can then modify the angular orientation of the blade 12 before tightening the pivot flange 19 in order to to immobilize the blade 12 in the desired angular position. The sealing device 45 can then be put back in place as explained above.

It could be envisaged that the sealing device 45 is coupled to the system for tightening the variable pitch of the blade 12. In this case, the compression screw 52 can ensure the tightening of a pivot flange 19.

The mobile compression washer 59 may also have a balancing weight function for the annular element 18.1. To this end, it is possible to vary its dimensions, in particular its thickness, or to vary its weight by local shrinkage or local addition of material so as to ensure rotational balancing of the annular element 18.1.

Of course, the different features, variants and/or embodiments of the present invention can be associated with each other in various combinations insofar as they are not incompatible or exclusive of each other.

Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms and other variants that a person skilled in the art may consider in the context of the present invention and in particular all combinations of the various modes of operation described previously, which may be taken separately or in combination.

Claims (13)

Extensible sealing device (45) characterized in that it comprises:
- a sealing plug (47) provided with a screw passage hole (53),
- a compression screw (52) inserted inside the screw passage hole (53),
- a deformable washer (58) having in the undeformed state a radial dimension (D1) less than or equal to a radial dimension (D2) of the sealing plug (47),
- a movable compression washer (59), and
- a screwing nut (60) intended to cooperate with a threaded end of the compression screw (52),
in such a way that a resultant tightening force (F3) of the compression screw (52) with the screwing nut (60) is capable of causing a displacement of the mobile compression washer (59) causing a radial deformation of the deformable washer (58) having in the deformed state a radial dimension (D1) greater than the radial dimension (D2) of the sealing plug (47). Extensible sealing device according to Claim 1, characterized in that the deformable washer (58) and the movable compression washer (59) are mounted on the compression screw (52) between an end face of the sealing plug (47) and the screwing nut (60), Extensible sealing device according to Claim 1 or 2, characterized in that the sealing plug (47) has a radial shoulder (48) located on the opposite side of the deformable washer (58). Extensible sealing device according to claim 3, characterized in that the radial shoulder (48) carries a seal (49). Extensible sealing device according to any one of Claims 1 to 4, characterized in that the sealing cap (47) is made of a rigid material. Extensible sealing device according to any one of Claims 1 to 5, characterized in that the deformable washer (58) is made of an elastic material, such as an elastomeric material. Extensible sealing device according to any one of Claims 1 to 6, characterized in that the compression screw (52) has a shouldered head (55). Extensible sealing device according to any one of Claims 1 to 6, characterized in that the compression screw (52) has a countersunk head. Extensible sealing device according to any one of Claims 1 to 8, characterized in that the movable compression washer (59) has the function of a balancing weight. Set comprising:
- a part (18.1) provided with a through opening (43) opening on the one hand into a first end face (44.1) of the part (18.1) and on the other hand into a second end face (44.2 ) of part (18.1), and
- an expandable sealing device (45) as defined in any one of the preceding claims disposed within the through opening of the part. Assembly according to Claim 10, characterized in that the part (18.1) is an annular element (18.1) of a fan ring (11). Assembly according to Claim 11, characterized in that the through-opening (43) is a window formed in a wall of the annular element (18.1), the said window (43) allowing access to at least one fixing member ( 23) securing a pivot flange (19). Assembly according to Claim 11 or 12, characterized in that the compression screw (52) is capable of ensuring the tightening of a pivot flange (19) providing angular retention of a pivot (13) secured to a blade.