Aircraft turbomachine propeller cone and its method of use

Abstract

A cone (1) for an aircraft turbomachine propeller (15) (20) extending along a longitudinal axis (X) oriented from upstream to downstream, the cone (1) comprising a conical wall (2) made of a rigid material suitable for absorbing the energy of a low impact without plastic deformation and suitable for breaking under a high impact, the cone (2) comprising a protective partition (3) extending transversely with respect to the longitudinal axis (X) and delimiting, with the conical wall (2), a cone volume, the protective partition (3) comprising a peripheral edge fixed to the conical wall (2) at an impact-protected area adjacent to the downstream end of the conical wall (2), the protective partition (3) being made of an elastic material suitable for absorbing the energy of the high impact by elastic deformation. Abstract figure: Figure 1

Description

Title of the invention: Aircraft turbomachine propeller cone and its method of use technical field

[0001] The present invention relates to the field of aircraft turbomachine propeller cones.

[0002] In a known manner, an aircraft turbomachine conventionally comprises, from upstream to downstream along the direction of airflow, one or more compressors, a combustion chamber, and one or more turbines. A propeller, known as a fan, is conventionally mounted upstream of the aircraft turbomachine and guides and accelerates the airflow within the aircraft turbomachine.

[0003] In a known manner, the propeller comprises a spinner and blades mounted on a hub that rotates about a longitudinal axis. The hub is driven in rotation by the turbine, typically via a speed reducer. The blades project outward about a radial axis and are typically mounted to rotate about the radial axis to change their pitch angle. The spinner comprises a conical wall that protects the rotating hub and the blade pitch system, and has an upstream leading edge that enhances aerodynamics.

[0004] As is known, impacts are likely to occur on the cone wall, some minor due to the impact of small birds or hail, for example, and others more significant due to large birds. It is imperative to prevent these impacts from damaging internal equipment such as the rotating hub and the blade pitching system, the replacement of which is costly and would require prolonged grounding. For this reason, the cone wall is traditionally made of a metallic material, such as stainless steel or aluminum, with high ductility to absorb the impact energy without breaking.

[0005] In practice, however, even minor impacts cause plastic deformation of the metal wall, disrupting aerodynamics and necessitating the replacement of the cone and grounding the aircraft. One solution would be to use a more rigid material for the cone wall to make it less prone to deformation in the event of minor impacts. However, this would have the undesirable consequence, in the event of a major impact, of increasing the risk of cone wall failure.

[0006] The invention thus relates to an aircraft turbomachine propeller cone capable of resisting, on the one hand, plastic deformation in the event of a low impact, and on the other hand, rupture in the event of a high impact. PRESENTATION OF THE INVENTION

[0007] The invention relates to a cone for an aircraft turbomachine propeller extending along a longitudinal axis oriented from upstream to downstream, the cone comprising: • A conical wall comprising a downstream end configured to be fixed onto a propeller blade retaining ring, the conical wall being made of a rigid material suitable for absorbing the energy of a low impact without plastic deformation and suitable for breaking under the effect of a high impact, • A protective partition extending transversely with respect to the longitudinal axis and delimiting with the conical wall a cone volume, the protective partition comprising a peripheral edge fixed to the conical wall at the level of an impact-protected area adjacent to the downstream end, the protective partition being made of an elastic material suitable to absorb the energy of the strong impact by elastic deformation.

[0008] In the event of an impact, the helix cone according to the invention advantageously comprises two protective barriers of different compositions and complementary functions: a conical wall forming an external barrier of overall protection in the event of a low impact, and a protective partition forming an internal barrier of targeted protection of internal equipment in the event of a high impact.

[0009] The invention advantageously proposes using a high-rigidity material for the conical wall, namely one with greater rigidity than materials used in the prior art, such as aluminum and stainless steel. The less ductile conical wall thus maintains an aerodynamic profile in the event of a minor impact and avoids replacement costs.

[0010] The elastic material of the protective bulkhead absorbs the energy of the strong impact through elastic deformation. This protects the expensive internal equipment, particularly the rotating hub and the blade pitching system, and reduces replacement costs.

[0011] According to a preferred aspect, the cone is configured to be driven in rotation about the longitudinal axis, which allows the protective partition to be tensioned by centrifugal effect.

[0012] According to one aspect of the invention, the rigid material of the conical wall is an organic matrix composite material, preferably comprising glass or carbon fibers. Such a material is both rigid and lightweight.

[0013] According to one aspect of the invention, the protective partition is in the form of a fabric made of aramid fibers, preferably Kevlar®. Such a material has very high tensile strength.

[0014] According to one aspect of the invention, the protective partition comprises a central portion extending upstream of the peripheral edge. This reduces the stresses exerted on the peripheral edge fixings during an impact.

[0015] According to one aspect of the invention, the cone comprises a reinforcement device fixed to the conical wall at the impact-protected area, the reinforcement device comprising at least one tab extending downstream of the protective partition, the tab being configured to bend plastically downstream upon a strong impact on the protective partition. The reinforcement device absorbs a portion of the impact energy, in synergy with the protective partition, for optimal protection.

[0016] Preferably, in a nominal state, the tab extends into contact with the protective partition. This increases the break resistance of the protective partition.

[0017] According to one aspect of the invention, in a nominal state, the tab extends upstream and is configured to partially press the protective partition against the conical wall. Preferably, the tab extends up from the point of attachment of the reinforcement device to the conical wall. This reduces the stresses exerted on the peripheral edge fasteners during an impact.

[0018] According to one aspect of the invention, in a nominal state, the tab comprises an end curved towards the longitudinal axis to facilitate the tab's folding during a strong impact. The deformation is advantageously pre-formed and allows the elastic deformation of the protective partition to be guided.

[0019] According to a preferred aspect, the reinforcement device is annular along the longitudinal axis to reinforce the protective partition over its entire circumference.

[0020] According to a preferred aspect, the reinforcement device comprises a metallic material, preferably aluminum, having ductility allowing it to be bent on itself without breaking.

[0021] According to one aspect of the invention, the cone comprises a winding drum around which the peripheral edge is folded in at least one forward and at least one reverse direction, the winding drum being fixed to the conical wall with the forward and reverse directions of the peripheral edge. This increases the number of attachment points and reduces the stresses exerted on each point during an impact.

[0022] According to one aspect of the invention, the winding drum, the forward and reverse paths of the peripheral edge are sandwiched between the reinforcement device and the conical wall. The protective partition, the reinforcement device, and the winding drum are advantageously fixed together in a compact and practical manner. The reinforcement device helps to secure the protective partition.

[0023] The invention also relates to a propeller for an aircraft turbomachine comprising a cone as described above, a plurality of blades and a hub rotating about the longitudinal axis configured to drive the cone and the blades in rotation.

[0024] According to one aspect, the propeller includes a blade retaining ring fixed to the downstream end of the cone.

[0025] According to one aspect, the propeller includes a system for setting the angle of the blades along a radial axis of rotation relative to the longitudinal axis.

[0026] The invention also relates to the assembly of an aircraft propeller and turbomachine.

[0027] The invention also relates to a method of using the aircraft turbomachine propeller cone as described above, in which: • Upon a minor impact on the conical wall, the conical wall absorbs the energy without plastic deformation, and • During a strong impact on the conical wall, the conical wall breaks and the protective partition deforms elastically to absorb the energy of the strong impact. PRESENTATION OF THE FIGURES

[0028] The invention will be better understood upon reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0029] Fig. 1 is a schematic representation in longitudinal half-section of an aircraft turbomachine equipped with a propeller according to one embodiment of the invention.

[0030] The [Fig.2] is a schematic longitudinal sectional representation of a helix cone in a nominal state according to one embodiment of the invention.

[0031] The [Fig.3] is a schematic longitudinal sectional representation of the peripheral edge of the protective partition and the cone reinforcement device of the [Fig.2] in the nominal state.

[0032] Fig. 4 is a schematic longitudinal section representation of the helix cone of Fig. 2 during a low impact.

[0033] Fig. 5 is a schematic longitudinal section representation of the helix cone of Fig. 2 during a strong impact.

[0034] Fig. 6 is a schematic longitudinal cross-sectional representation of the peripheral edge of the protective partition and the reinforcement device of Fig. 3 during a strong impact.

[0035] It should be noted that the figures set out the invention in detail to implement the invention, said figures being of course able to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0036] With reference to [Fig. 1], the invention relates to a propeller cone 15 for an aircraft turbomachine 30. The aircraft turbomachine 30 conventionally comprises, from upstream to downstream according to the direction of airflow during a thrust phase, one or more compressors 23, 24, a combustion chamber 25 and one or more turbines 26, 27. The propeller 15, also known as the fan, is conventionally mounted upstream of the aircraft turbomachine 30 and guides and accelerates the airflow in the aircraft turbomachine 30.

[0037] With reference to [Fig. 1], the propeller 15 conventionally comprises a cone 1, known as the "spinner," and blades 21 which are driven in rotation about the longitudinal axis X by a rotating hub 19. The rotating hub 19 is typically driven in rotation by a shaft 22 connected to the turbine 27, preferably via a speed reducer (not shown). The cone 1 is alternatively mounted in a fixed position.

[0038] With further reference to [Fig. 1], the cone 1 comprises a conical wall 2 having a leading edge pointing upstream and a downstream end 6 fixed to a retaining ring 18 for the blades 21 (see [Fig. 2]). The blades 21 project from the retaining ring 18 along a radial axis Y with respect to the longitudinal axis X. The blades 21 are typically mounted to rotate about the radial axis Y to change their pitch angle.

[0039] According to the invention, with reference to figures 1 and 2, the conical wall 2 of the cone 1 is made of a rigid material adapted, on the one hand, to absorb the energy of a weak impact A (see [Fig.4]) without plastic deformation, and on the other hand, to break under the effect of a strong impact B (see figures 5 and 6).

[0040] According to the invention and with reference to Figures 1 and 2, the cone 1 also includes a protective partition 3 extending transversely with respect to the longitudinal axis X and delimiting, together with the conical wall 2, a cone volume V. The protective partition 3 includes a peripheral edge 11 fixed to the conical wall 2 at the level of an impact-protected zone 7 adjacent to the downstream end 6. The impact-protected zone 7 extends tangentially with respect to the generatrix of the cone 1. The protective partition 3 is made of an elastic material suitable for absorbing the energy of the strong impact B by elastic deformation (see Figures 5 and 6).

[0041] According to a preferred aspect of the invention also illustrated in Figures 1 and 2, the cone 1 also includes a reinforcement device 4 fixed to the conical wall 2 at the level of the impact-protected area 7. The reinforcement device 4 comprises one or more tabs 15 extend downstream of the protective partition 3, from the point of attachment of the reinforcement device to the conical wall. The tab 15 of the reinforcement device 4 is configured to bend plastically downstream during the strong impact B on the protective partition 3 (see [Fig. 6]).

[0042] In the event of an impact, the helix cone 1 according to the invention advantageously comprises two protective barriers of different compositions and complementary functions: a conical wall 2 forming an external barrier of overall protection in the event of a low impact A (see [Fig.4]), and a protective partition 3 forming an internal barrier of targeted protection of internal equipment in the event of a high impact B (see figures 5 and 6).

[0043] A weak impact A is characterized by a low-intensity shock on the conical wall 2, the impact energy preferably being less than 13 kJ. A weak impact A is typically caused by hail or the impact of a bird of low mass, namely less than 2.5 kg. A strong impact B, on the other hand, corresponds to a high-intensity shock on the conical wall 2, the impact energy preferably being greater than 13 kJ. A strong impact B is typically caused by the impact of a bird of high mass, namely greater than 2.5 kg.

[0044] With reference to Figures 1 and 2, the conical wall 2 forms the shell of the cone 1 and has an aerodynamic profile with an upstream leading edge that promotes airflow. The conical wall 2 is preferably a single piece.

[0045] The invention advantageously proposes using a high-stiffness material for the conical wall 2, namely, one with a stiffness greater than that of materials used in the prior art, such as aluminum and stainless steel. This makes the conical wall 2 less ductile and therefore less prone to deformation. The conical wall 2 thus maintains an aerodynamic profile in the event of a low impact A and avoids replacement costs. On the other hand, the high stiffness of the conical wall 2 tends to promote its failure in the event of a high impact B.

[0046] Preferably, the conical wall 2 is made of an organic matrix composite material, preferably comprising glass or carbon fibers. The composite material preferably comprises a thermosetting matrix. The conical wall 2 thus has high mechanical strength and low mass.

[0047] With reference to Figures 1 and 2, the protective partition 3 extends transversely internally within the cone 1, downstream of the leading edge of the conical wall 2. The protective partition 3 extends over the entire cross-section of the conical wall 2 with respect to the longitudinal axis X. The protective partition 3 is fixed to the conical wall 2 near the downstream end 6, at a so-called impact-protected zone 7, in that it cannot constitute a point of impact due to its position set back from the leading edge. The protective partition 3 is thus effective regardless of the location of the impact, especially if the point of impact is located outside the leading edge.

[0048] The protective partition 3 advantageously incorporates a suitable elastic material that, when a strong impact B penetrates the conical wall 2, absorbs the energy of the strong impact B through elastic deformation. This protects costly internal equipment, such as the rotating hub 19 and the blade pitch control system 20. The protective partition 3 thus limits damage from a strong impact B and reduces replacement costs. Preferably, the protective partition 3 is made of aramid fiber fabric, typically Kevlar®, which has very high tensile strength due to its elasticity. The protective partition 3 may be coated and / or have folds and / or seams for reinforcement. However, the protective partition 3 does not contribute to the aerodynamic profile of the cone 1.

[0049] With reference to [Fig. 3], the peripheral edge 11 of the protective partition 3 is fixed against the inner face of the conical wall 2 by means of one or more fastening devices 5, typically in the form of screw-nut assemblies or rivets. The fastening devices 5 are preferably distributed around the circumference of the conical wall 2 at the level of the impact-protected area 7. The fastening devices 5 keep the protective partition 3 taut. The rotation of the propeller 15 also contributes to tensioning the protective partition 3 by centrifugal force.

[0050] Preferably and as illustrated in [Fig.3], the central portion 14 of the protective partition 3 extends upstream of the peripheral edge 11. This limits the stresses exerted at the fixing of the peripheral edge 11 and increases the breaking strength of the protective partition 3.

[0051] According to a preferred aspect illustrated in [Fig. 3], the peripheral edge 11 is folded around a winding drum 8 in at least one forward fold 12 and at least one return fold 13. The winding drum 8 is fixed through the forward fold 12 and the return fold 13 to the conical wall 2 by means of the fastening device 5. The forward fold 12 is typically sandwiched between an external face 9 of the winding drum 8 and the internal face of the conical wall 2. The return fold 13 is sandwiched between an internal face 10 of the winding drum 8 and the fastening device 5. This helps to secure the protective partition 3 and increases the number of fastening points, thereby reducing the stresses exerted on each one.

[0052] Preferably, the winding drum 8 is in the form of a ring with longitudinal axis X holding the protective partition 3 around its entire circumference. Preferably, the winding drum 8 has an oblong cross-section to facilitate both winding and attachment to the conical wall 2.

[0053] According to a preferred aspect illustrated in figures 2 to 6 and as described previously, a reinforcement device 4 is fixed to the conical wall 2 at the level of the impact-protected area 7. The peripheral edge 11 of the protective partition 3, namely in this example the forward 12 and the return 13 around the winding drum 8, is sandwiched between the reinforcement device 4 and the conical wall 2.

[0054] As illustrated in [Fig. 3], the reinforcement device 4 comprises one or more tabs 15 extending downstream of the protective partition 3. In a nominal state N, namely in the absence of an impact A, B, the tab 15 typically extends into contact with the protective partition 3. Preferably, in the nominal state N, the tab 15 extends upstream and is configured to partially press the protective partition 3 against the conical wall 2. The reinforcement device 4 thus improves the retention of the protective partition 3.

[0055] As illustrated in Figures 5 and 6, during a strong impact B which has passed through the conical wall 2 at the level of a pierced area Q, the tab 15 of the reinforcement device 4 is configured to bend plastically downstream under the effect of the elastic deformation of the protective partition 3. The tab 15 advantageously allows to absorb part of the energy of the strong impact B, in a complementary manner to the protective partition 3.

[0056] According to a preferred aspect illustrated in [Fig.3], in the nominal state N, the leg 15 includes a curved end 16 towards the longitudinal axis X to pre-form the bending of the leg 15 during the strong impact B.

[0057] Preferably, the reinforcement device comprises a ductile metallic material, such as aluminum, allowing the tabs 15 to bend. Preferably, the reinforcement device 4 is a single piece. Preferably, the tab 15 projects over a length less than 10% of the diameter of the conical wall 2 at the downstream end 6. Such a reinforcement device 4 advantageously has a small size and mass.

[0058] Preferably, the reinforcement device 4 is annular with longitudinal axis X to reinforce the protective partition 3 around its entire circumference. Also preferably, the reinforcement device 4 comprises several tabs 15 distributed around its circumference. The tabs 15 can thus bend differently from one another depending on the location of the strong impact B.

[0059] The method of using the cone 1 of helix 15 is described below with reference to figures 2 to 6.

[0060] With reference to Figures 2 and 3, in a nominal state N, namely in the absence of impact A, B, the conical wall 2 has an aerodynamic profile that promotes the flow of air from upstream to downstream during a thrust phase. In the nominal state N, the protective partition 3 is kept taut by the fastening device. 5, by the winding drum 8 and by the centrifugal effect of the rotation of the propeller 15. Still in the nominal state N, the reinforcement device 4 extends in projection upstream.

[0061] With reference to [Fig. 4], during a minor impact A at a point P on the conical wall 2, the conical wall 2 absorbs the impact energy without deformation due to its high rigidity. The protective partition 3 and the reinforcing device 4 are not exposed to the minor impact A. Advantageously, a minor impact A does not require any replacement and does not degrade the aerodynamic profile of the conical wall 2.

[0062] With reference to Figures 5 and 6, during a strong impact B, the strong impact B ruptures the conical wall 2, forming a breached area Q, and then comes into contact with the protective partition 3. The protective partition 3 and the reinforcing device 4, under the effect of the strong impact B, absorb the received energy, respectively by stretching downstream and bending downstream. This advantageously protects the internal equipment of the cone 1 and limits damage and repair costs.

Claims

Demands

1. Cone (1) for an aircraft turbomachine propeller (15) (20) extending along a longitudinal axis (X) oriented upstream to downstream, the cone (1) comprising: • A conical wall (2) including a downstream end (6) configured to be fixed to a retaining ring (18) for the propeller blades (21) (15), the conical wall (2) being made of a rigid material suitable for absorbing the energy of a low impact (A) without plastic deformation and suitable for breaking under the effect of a high impact (B), • A protective partition (3) extending transversely with respect to the longitudinal axis (X) and delimiting with the conical wall (2) a cone volume (V), the protective partition (3) including a peripheral edge (11) fixed to the conical wall (2) at an impact-protected area (7) adjacent to the downstream end (6), the protective partition (3) being in an elastic material adapted to absorb the energy of the strong impact (B) by elastic deformation.

2. Cone (1) according to claim 1, wherein the rigid material of the conical wall (2) is an organic matrix composite material, preferably comprising glass or carbon fibers.

3. Cone (1) according to any one of claims 1 and 2, wherein the protective partition (3) is in the form of a fabric made of aramid fibers.

4. Cone (1) according to any one of claims 1 to 3, wherein the protective partition (3) comprises a central portion (14) extending upstream of the peripheral edge (11).

5. Cone (1) according to any one of claims 1 to 4, comprising a reinforcement device (4) fixed to the conical wall (2) at the level of the impact-protected area (7), the reinforcement device (4) comprising at least one tab (15) extending downstream of the protective partition (3), the tab (15) being configured to bend plastically downstream during the strong impact (B) on the protective partition (3).

6. Cone (1) according to claim 5, wherein, in a nominal state (N), the lug (15) extends upstream and is configured to partially attach the protective partition (3) against the conical wall (2).

7. Cone (1) according to any one of claims 5 and 6, wherein, in a nominal state (N), the leg (15) comprises a curved end (16) towards the longitudinal axis (X) to promote the bending of the leg (15) during the strong impact (B).

8. Cone (1) according to any one of claims 1 to 7, comprising a winding drum (8) around which the peripheral edge (11) is folded in at least one forward (12) and at least one return (13), the winding drum (8) being fixed with the forward (12) and the return (13) of the peripheral edge (11) to the conical wall (2).

9. Cone (1) according to claim 8 taken in combination with claim 5, wherein the winding drum (8), the forward (12) and the return (13) of the peripheral edge (11) are sandwiched between the reinforcement device (4) and the conical wall (2).

10. A method of using the cone (1) according to any one of claims 1 to 9, wherein: • During a weak impact (A) on the conical wall (2), the conical wall (2) absorbs the energy without plastic deformation, and • During a strong impact (B) on the conical wall (2), the conical wall (2) breaks and the protective partition (3) deforms elastically to absorb the energy of the strong impact (B).

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