FR3142781A1 - FAN BLADE Clamping SYSTEM PROVIDED WITH A RETENTION WEDGE - Google Patents

Abstract

The invention relates to a fan for an aircraft turbomachine test bench comprising: - an annular hub (11) comprising at least one blade root housing (13), - at least one blade (12) provided a blade root (18), - a clamping system (21) in the position of the blade (12) comprising: - a clamp (22) mounted in the blade root housing (13), and - a retention wedge (30) arranged inside a groove (19) made in the blade root (18), said retention wedge (30) being intended to come to bear against the clamp (22) . Figure 5

Description

FAN BLADE Clamping SYSTEM PROVIDED WITH A RETENTION WEDGE

The present invention relates to a fan blade clamping system provided with a retention wedge.

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 nozzle.

Figures 1a and 1b show a fan 1 comprising a hub 2 having an axis hub 2. The blades 3 are of the variable pitch type, that is to say they can be set in a predetermined angular position around their respective Y axis in order to adapt and optimize this position depending in particular of the turbomachine speed.

In practice, the blades 3 can be moved over more than 90° around their axis Y, from a "flag" position in which one blade is substantially aligned with the axis , and an "inverter" position (from the English "reverse") in which a blade is capable of generating an air flow reversed relative to the direction of flow of the air flow in the turbomachine, as is illustrated by the .

It is known to use a system capable of locking different angular positions of the blades during fan tests. This clamping system is integrated into a turbomachine test bench including numerous measurement equipment making it possible to identify the optimal angular positions of the blades.

In order to integrate a variable timing system into a one-piece hub, it is necessary to mount the blade in a radial direction relative to the hub axis. This type of blade mounting requires ensuring radial retention of the blade subject to significant centrifugal forces during its rotation. No existing device makes it possible to achieve satisfactory blocking of the blade in the radial direction in a one-piece configuration of the hub.

The invention aims to effectively remedy the aforementioned drawbacks by proposing a fan for an aircraft turbomachine test bench comprising:
- an annular hub comprising at least one blade root housing,
- at least one blade equipped with a blade root,
- a clamping system in the position of the blade comprising:
- a clamp mounted in the blade root housing, and
- a retention wedge disposed inside a groove made in the blade root, said retention wedge being intended to come to bear against the clamp.

The invention thus makes it possible to ensure radial retention of the fan blade mounted in a clamping system integrated into a one-piece fan hub. The invention also facilitates the assembly and disassembly of the blade in a radial direction inside the blade root housing.

According to one embodiment of the invention, the retention wedge comprises two branches connected together by a connecting portion so as to have a U shape.

According to one embodiment of the invention, the branches of the retention wedge are each inserted inside a through opening made in the clamp.

According to one embodiment of the invention, each branch of the retention wedge comprises a hook intended to be inserted into the through opening of the clamp to ensure retention of the retention wedge and to prevent extraction of the retention wedge when the retention wedge abuts with one face of the clamp having the through opening.

According to one embodiment of the invention, the clamp comprises a deformable portion delimiting a passage opening of the blade root, so that the deformable portion extends around a circumference of said blade root, a clamping member ensuring tightening the deformable portion around the blade root so as to immobilize the blade in a desired angular position of the blade.

According to one embodiment of the invention, the deformable portion of tubular shape comprises a plurality of radial slots.

According to one embodiment of the invention, the clamping member is a clamp located around the deformable portion.

According to one embodiment of the invention, an elastic pin ensures rotational locking of the clamp relative to the clamp.

According to one embodiment of the invention, the deformable portion comprises a split ring.

According to one embodiment of the invention, the clamping member is a screw-nut assembly cooperating with protruding ears with holes each coming from one end of the split ring.

The present invention will be better understood and other characteristics and advantages will appear further on reading the detailed description which follows including embodiments given for illustrative purposes 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, where appropriate, contribute to its definition, on which:

Figures 1a and 1b, already described, show a turbomachine fan provided with variable-pitch blades respectively in a "flag" position and an "inverter"position;

There is a perspective view of a fan for an aircraft turbomachine test bench provided with a blade clamping system according to the invention;

There is an exploded perspective view of a blade root, a retaining wedge and a clamp of a blade clamping system according to a first embodiment of the invention;

There is a perspective view of a clamp of a blade clamping system according to the first embodiment of the invention and of a retention wedge arranged around a blade root;

There is a longitudinal sectional view of a clamp of a blade clamping system according to the first embodiment of the invention and of a retaining wedge arranged around a blade root;

There is a perspective view of a clamp of a blade clamping system according to the first embodiment of the invention;

There is an exploded perspective view of a blade root, a retaining wedge and a clamp of a blade clamping system according to a second embodiment of the invention;

There is a perspective view of a clamp of a blade clamping system according to the second embodiment of the invention and of a retention wedge arranged around a blade root;

There is a longitudinal sectional view of a clamp of a blade clamping system according to the second embodiment of the invention and of a retention wedge arranged around a blade root;

There is a perspective view of a clamp of a blade clamping system according to the second embodiment of the invention;

There is a perspective view of a retaining wedge according to the present invention;

Figures 12a, 12b, 12c, and 12d illustrate the different stages of mounting the retention wedge according to the present invention making it possible to ensure radial retention of the blade root.

It should be noted that, in Figures 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.

There shows a fan 10 for an aircraft turbomachine test bench comprising an annular hub 11 having an axis X and a plurality of blades 12.

The annular hub 11 comprises a plurality of blade root receiving housings 13. Advantageously, the annular hub 11 is a one-piece hub, that is to say it is made in a single part.

As can be seen on the , each blade root housing 13 comprises a retaining wall 15. The retaining wall 15 comes from an internal face of the housing 13 and extends radially, relative to the axis Y, from the internal face of the housing 13 towards the center of housing 13. The retaining wall 15 has a passage opening 16 for a blade root 18.

The blades 12 extend radially towards the outside of the hub 11 along their Y axis. The blades 12 are distributed angularly in a regular manner along a circumference of the hub 11. Each blade 12 is provided with a blade root 18 of the shape generally cylindrical. Each blade root 18 has a circumferential groove 19.

A clamping system 21 in the position of the blade 12 makes it possible, in an unlocked state, to authorize rotation of the blade root 18 inside a corresponding housing 13 around the Y axis so as to select a desired angular position of the blade 12 for a test and in a locked state to immobilize the blade 12 inside the housing 13 in the desired angular position.

The clamping system 21 comprises a clamp 22 with axis Y' visible in Figures 6 and 10 intended to be mounted in a corresponding blade root housing 13.

The clamp 22 comprises a mounting portion 23 of cylindrical shape provided with a passage opening 24 of the blade root 18.

The clamp 22 further comprises a deformable portion 25 delimiting a passage opening 26 of the blade root 18, so that the deformable portion 25 extends around a circumference of said blade root 18. The mounting portion 23 and the deformable portion 25 are interconnected by a connecting wall 29. The passage openings 24, 26 of the mounting portion 23 and the deformable portion 25 are coaxial with each other. The mounting portion 23 and the deformable portion 25 are spaced apart from each other to allow the installation of a retention wedge 30 intended to be placed inside the groove 19 of the blade root 18, as shown on Figures 5 and 9. The ends of the retention wedge 30 are inserted inside through openings 31 made in the connecting wall 29 (cf. ). The retention wedge 30, the operation of which is described in more detail below, makes it possible to ensure radial retention of the blade 12 relative to the axis X. The retention wedge 30 also makes it possible to ensure aerodynamic continuity of the primary vein of the turbomachine by the alignment of the radially external face of the pivot 12 and the external face of the hub 11.

A tightening member 34 ensures tightening of the deformable portion 25 around the blade root 18 so as to immobilize the blade 12 in a desired angular position. The contact between the deformable portion 25 and the blade root 18 is a cylindrical contact.

In the embodiment of Figures 3, 4, 5, and 6, the mounting portion 23 is provided with flats 36 at its external periphery intended to cooperate with complementary shapes made in the hub 11 to keep the clamp 22 locked in rotation relative to the hub 11 along the axis Y. The mounting portion 23 is intended to come to bear against the retaining wall 15 of a blade root housing 13, as shown on the . In this case, an axial end face of the mounting portion 23 with respect to the axis Y' comes to rest against the retaining wall 15.

As can be seen on the , the deformable portion 25 of tubular shape comprises a plurality of radial slots 37. The radial slots 37 are slots passing through the thickness of a wall 38 of the deformable portion 25. The slots 37 are made in the wall 38 having a thickness weaker than a wall of the mounting portion 23. The slots 37 are preferably angularly spaced regularly along a circumference of the deformable portion 25. Regular spacing of the slots 37 is however not essential for implementation of the invention.

An anti-rotation axis 40 visible on the cooperates on the one hand with the clamp 22 and on the other hand with the hub 11 to block the rotation of the clamp 22 inside the blade root housing 13. The axis 40 makes it possible to prevent rotation of the clamp 22 along the Y axis of the blade 12 during the period of rotation of the fan 10.

The clamping member 34 is a clamping collar 41 located around the deformable portion 25. In this case, the clamping collar 41 is arranged in a groove 42 delimited by two flanges 43 arranged axially on either side of the deformable portion 25 . The clamp 41 is tightened by a screw 45-nut 46 assembly mounted in two projecting ears 47 of the clamp 41 (cf. ). The projecting ears 47 have holes to receive the screw 45. The tightening action of the collar 41 causes the tightening of the blade 12 by a cylindrical support of the deformable portion 25 of the clamp 22 around the blade root 18. L The blade 12 is thus kept locked in rotation around its axis Y.

A spring pin 50 shown on the ensures that the clamp 41 is blocked in rotation relative to the clamp 22. The elastic pin 50 makes it possible to eliminate the rotation of the clamp 41 around the clamp 22 which can modify the balancing of the fan 10 between each setting. For this purpose, the elastic pin 50 is inserted inside a through opening made in the clamp 41 and cooperates with a blind opening made in the deformable portion 25.

In the embodiment of Figures 7, 8, 9, and 10, the mounting portion 23 is provided with a shoulder 51 intended to come to bear against the retaining wall 15 of a corresponding blade root housing 13 (cf. ). The shoulder 51 thus ensures radial retention of the clamp 22. As can be seen in the , the mounting portion 23 is provided with flats 36 at its external periphery intended to cooperate with complementary shapes made in the hub 11 to keep the clamp 22 locked in rotation relative to the hub 11 along the Y axis.

The deformable portion 25 comprises a split ring 53. The split ring 53 has an annular shape of axial orientation relative to the axis Y' of the clamp 22. The ends of the ring 53 separated by a slot 54 are extended by two protruding ears with holes 57. The projecting ears with holes 57 extend radially projecting relative to the axis Y' of the clamp 22.

As illustrated in Figures 8 and 9, the clamping member 34 is a screw 58-nut 59 assembly cooperating with the protruding ears with holes 57 coming from the ends of the split ring 53. The screw 58 is inserted at the inside the holes of the protruding ears 57 and the nut 59 is screwed onto the screw 58. When the blade 12 has the desired angular position, it is sufficient to clamp it by the tightening action of the screw 58 and the nut 59. This action has the effect of deforming the split ring 53 of the clamp 22, the slot 54 of which has the clearance necessary for its deformation. The deformation of the clamp 22 has the effect of tightening the blade root 18 of the blade 12 on the contact zone with the split ring 53 and thus blocking the blade 12 in rotation relative to the hub 11.

As can be seen in Figures 3, 5, 7, and 9, the retention wedge 30 is arranged inside the groove 19 made in the blade root 18. The retention wedge 30 is intended to come resting against the clamp 22. In this case, the retention wedge comes to rest against a support face 61 of the clamp 22. The support face 61 of the clamp 22 extends in a radial plane relative to to the axis Y' of the clamp 22. Once the assembly is tightened, the retention wedge 30 makes it possible to block the blade 12 radially when it is subjected to a centrifugal force.

More precisely, as illustrated in the , the retention wedge 30 has two branches 30.1, 30.2 connected together by a connecting portion 30.3 so as to have a U shape.

The branches 30.1, 30.2 of the U are each inserted inside an opening 31 made in the clamp 22. Each branch 30.1, 30.2 comprises a hook 64 intended to be inserted into the opening 31 of the clamp 22 to ensure a retention of the retention wedge 30 and to prevent extraction of the retention wedge 30 when the retention wedge 30 abuts with one face of the clamp 22 comprising the through opening 31. The retention of the retention wedge 30 is carried out in an ortho-radial direction with respect to the axis

We describe below, with reference to Figures 12a to 12d, the assembly of the retention wedge 30 of the clamping system 21 of the blade 12 according to the invention.

As illustrated in the , before installing the retention wedge 30, it is necessary to pre-position the blade 12 set back radially relative to the external face of the hub 11.

As illustrated in the , once the blade 12 is recessed, the groove 19 of the blade root 18 and the openings 31 of the clamping system 21 are aligned to allow the installation of retention wedge 30. The retention wedge 30 is inserted into the groove 19 of the blade root 18 and the hook-shaped ends 64 of the branches 30.1, 30.2 pass inside the openings 31 of the clamping system 21.

As illustrated in the , the blade 12 is then raised relative to the clamp 22 in a radial direction D1 with respect to the axis in contact with a lower face of the retention wedge 30 (here radially internal) and that the upper face of the retention wedge 30 (here radially external) is in contact with the support face 61 of the clamp 22 provided in the mounting portion 23. A radially external face of the blade pivot 12 is then located in the extension of the external face of the hub 11 to ensure aerodynamic continuity of the primary flow of the turbomachine.

The hooks 64 then ensure blocking of the retention wedge 30, to the extent that it is no longer possible for the retention wedge 30 to pass through the openings 31 of the clamp 22 through which the branches 30.1, 30.2 have been introduced .

It is possible to carry out possible measurement readings in order to take, if necessary, the thickness of the retention wedge 30 in order to precisely position the blade 12 in its environment in a radial direction.

As is illustrated by the , tightening the screw 58-nut 59 assembly ensures tightening of the clamp 22 around the blade root 18 so as to immobilize the blade 12 in a desired angular position.

Once the clamping system 21 is locked, the blade 12 is precisely positioned radially and the force generated by the centrifugal force is partly taken up by the retention wedge 30.

In order to modify the angular position of a blade 12, the clamp 22 is slightly loosened in order to be able to modify the orientation of the blades 12 according to the desired angle.

The operations of manipulating the blade 12 and tightening or loosening the clamp 22 can be carried out by a human operator or a robot.

The invention thus makes it possible to carry out a rapid modification of the setting of the blades 12 between two tests. In addition, in the event of breakage of a blade 12, dismantling can be carried out in situ, which represents a significant saving of time.

Of course, the different features, variants and/or embodiments of the present invention can be associated with each other in various combinations as long 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 those skilled in the art may consider in the context of the present invention and in particular all combinations of the different modes of operation described above, which can be taken separately or in combination.

Claims (10)

Blower (10) for an aircraft turbomachine test bench comprising:
- an annular hub (11) comprising at least one blade root housing (13),
- at least one blade (12) provided with a blade root (18),
characterized in that said fan (10) further comprises a clamping system (21) in the position of the blade (12) comprising:
- a clamp (22) mounted in the blade root housing (13), and
- a retention wedge (30) arranged inside a groove (19) made in the blade root (18), said retention wedge (30) being intended to come to bear against the clamp (22) . Blower according to claim 1, characterized in that the retention wedge (30) comprises two branches (30.1, 30.2) interconnected by a connecting portion (30.3) so as to have a U shape. Blower according to claim 2, characterized in that the branches (30.1, 30.2) of the retention wedge (30) are each inserted inside a through opening (31) made in the clamp (22). Blower according to claim 2 or 3, characterized in that each branch (30.1, 30.2) of the retention wedge (30) comprises a hook (64) intended to be inserted into the through opening (31) of the clamp (22 ) to ensure retention of the retention wedge (30) and to prevent extraction of the retention wedge (30) when the retention wedge (30) abuts with one face of the clamp (22) having the opening through (31). Blower according to any one of claims 1 to 4, characterized in that the clamp (22) comprises a deformable portion (25) delimiting a passage opening (26) of the blade root (18), so that the portion deformable portion (25) extends around a circumference of said blade root (18), a clamping member (34) ensuring tightening of the deformable portion (25) around the blade root (18) so as to immobilize the blade (12) in a desired angular position of the blade (12). Blower according to claim 5, characterized in that the deformable portion (25) of tubular shape comprises a plurality of radial slots (37). Blower according to claim 6, characterized in that the clamping member (34) is a clamp (41) located around the deformable portion (25). Blower according to claim 7, characterized in that an elastic pin (50) ensures rotational locking of the clamp (41) relative to the clamp (22). Blower according to claim 5, characterized in that the deformable portion (25) comprises a split ring (53). Blower according to claim 9, characterized in that the clamping member (34) is a screw (58)-nut (59) assembly cooperating with perforated projecting ears (57) each coming from one end of the split ring (53).