Variable pitch bladed propeller with blade support featuring easy disassembly

Abstract

Variable pitch propeller, comprising at least two blades and a rotor with a hub, the hub comprising a blade support for each blade of the propeller, each blade comprising a blade foot designed to cooperate with one of said blade supports in order to maintain the blade in position in the rotor while allowing the pitch to be changed, comprising: - a blade foot comprising a composite core (11), disposed in an outer sleeve (13) of the blade support resting on it by means of an elastomer buffer (12), - a blade support (4) having an upper bearing (2) and a lower bearing (3) in contact with the outer sleeve (13), the blade support (4) also comprising at least two half-jaws (14) cooperating with the composite core (11) in order to prevent the blade foot from moving in a radial direction relative to the blade support (4). Figure for the abridged version: Fig 8

Description

Title of the invention: Variable pitch bladed propeller with blade support featuring easy disassembly technical field

[0001] The invention has as its technical field unfaired propellers and more specifically such variable pitch bladed propellers. Previous techniques

[0002] A variable-pitch bladed propeller comprises one or more blades, also called vanes, driven in rotation by an engine. This engine may be, in particular, a turbomachine or an electric motor. The common application is a turboprop engine, but can be extended to unducted engines, also known as "open rotor" or "unducted fan" engines.

[0003] The propeller comprises a rotor element fixed on the motor shaft and comprising several cylindrical housings distributed around its periphery, each equipped with a blade support.

[0004] Each propeller blade includes a foot, designed to be engaged in a support of the rotor element. Each foot is associated with a lower bearing and an upper bearing, in particular roller bearings, in which the rollers are each held in position by an inner ring and an outer ring.

[0005] Each blade foot also includes an annular portion radially internal to the foot axis, rotationally coupled to the support foot, and an annular portion radially external to the foot axis. The internal and external portions are capable of pivoting relative to each other, for example via the lower and upper bearings.

[0006] The supports and internal parts of the bearings can rotate in the housings of the rotor element and are driven in rotation around the axes of the blades or feet by appropriate means, so as to adjust the angular pitch of the blades.

[0007] The mounting of a propeller blade according to the prior art is illustrated by figure [Fig.1]. The rotor comprises a hub provided with blade supports arranged in openings and in each of which a blade foot is inserted.

[0008] Figure [Fig.1] illustrates the mounting of the upper bearing of the foot of the blade.

[0009] Thus, the blade foot 1 comprises an upper bearing 2 including an inner ring 2al, 2a2, rollers 2bl, 2b2, and an outer ring 2c. The inner ring 2al, 2a2 is in two parts to allow its installation while the sleeve is shouldered above the upper bearing. The outer ring 2c is moved into contact with the rollers 2bl, 2b2 after their installation on the inner ring 2a. The rotor includes A hub is provided with blade supports 4 arranged in openings 4a, and in each of these openings is inserted a blade foot 1, as illustrated in Figures [Fig. 2] and [Fig. 3]. It should be noted that the outer ring 3a of the lower bearing 3 is pre-positioned at the periphery of the opening 4a through which the blade foot 1 is inserted. In all figures [Fig. 1] to [Fig. 8], an upper blade foot nut, referenced 3d, is shown.

[0010] Figure [Fig. 4] illustrates the installation of the inner ring 3cl,3c2 of the lower bearing 3 onto the blade root. As with the inner ring 2al,2a2, the inner ring 3cl,3c2 is in two parts to allow its installation while the sleeve is shouldered below the lower bearing. Figure [Fig. 5] illustrates the installation of the rollers 3b of the lower bearing 3 onto the inner ring 3cl,3c2 and the tightening of the outer ring 2c of the upper bearing 2 into an upper nut 3d of the blade root.

[0011] Figure [Fig.6] illustrates the raising of the blade foot in the blade support 4 causing the movement of the inner ring 3c l,3c2 until it contacts the rollers 3b of the lower bearing 3.

[0012] Figure [Fig.7] illustrates the installation of a crankshaft 5 on the blade foot in order to control the angular timing of the blade.

[0013] The major drawback of the current solution lies in the long disassembly / reassembly time due to the number of parts involved, and due to the chain of steps to be respected as well as the risks of damage related to the handling of many elements of the blade, in particular during the disassembly of the bearings.

[0014] Another disadvantage lies in the need to remove the bearings to dismantle the blade.

[0015] From the prior art, we also know of document EP0324617A2 describing a blade mounting system. Such a system also involves removing bearings to disassemble the blade. It therefore does not resolve the drawbacks identified above.

[0016] The technical problem solved by the present invention is to remedy the drawbacks of the prior art, in particular the need to dismantle bearings in order to dismantle a blade. Description of the invention

[0017] The invention relates to a variable-pitch bladed propeller comprising at least two blades and a rotor equipped with a hub, the hub comprising a blade support for each blade of the propeller, each blade comprising a blade root designed to cooperate with one of said blade supports so as to maintain the blade in position in the rotor while allowing the pitch to be changed. The propeller comprises:

[0018] - a blade foot comprising a composite core having a generally cylindrical with an axis of revolution, the composite core being equipped with a non-opening axial cavity, arranged in an outer sleeve of the blade support, which is also cylindrical, and resting on it via an elastomer buffer,

[0019] - a blade support provided with an upper bearing and a lower bearing in contact with the outer sleeve, the blade support also comprising at least two half-jaws cooperating with the composite core so as to prevent the blade foot from moving in a radial direction relative to the axis of the blade support,

[0020] - the composite core, the axial cavity and the outer sheath sharing the same axis of revolution so as to be concentric.

[0021] The composite core may have a cylindrical shape, with or without radial narrowing.

[0022] The elastomer pad can be in the shape of a crown, the composite core then comprising a radial shoulder designed to bear against a surface of the elastomer pad, the outer sleeve comprising a flat to accommodate the elastomer pad.

[0023] The elastomer pad may be conical in shape, the outer sleeve comprising an axial shoulder designed to support a surface of the elastomer pad, the composite core comprising a conical surface opposite the elastomer pad.

[0024] The propeller may include a crankshaft integrated into the outer sleeve or a crankshaft integrated into a half-jaw.

[0025] The half-jaws may have an angular sector shape so as to be in contact with the entire periphery of the blade foot, the half-jaws being able to be provided with radial shoulders at their ends, the shoulder of a half-jaw being secured to the shoulder of an adjacent half-jaw by means of reversible securing means, such as screws and threaded holes.

[0026] The propeller may include fastening means preventing the opening of the jaw halves.

[0027] The means of securing may be a nut and a corresponding thread provided on the outer surface of the half-jaws, the nut being screwed onto the thread of the half-jaws in order to prevent them from opening.

[0028] The means of securing may be a plurality of screws or bolts as well as a plurality of corresponding threaded holes provided in the outer sleeve of the blade support, the plurality of screws or bolts being screwed into the plurality of threaded holes in order to prevent the opening of the half-jaws.

[0029] A blade can include an inner sleeve disposed in the axial cavity of the composite core and an axial reinforcement disposed in the inner sleeve. Brief description of the drawings

[0030] Other objects, features and advantages of the invention will become apparent from the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0031] - Figures [Fig. 1] to [Fig. 7] illustrate the assembly steps of a propeller blade of an "open fan" turboprop engine according to the state of the art,

[0032] - Figure [Fig.8] illustrates the main elements of a paddle foot according to the invention,

[0033] - Figures [Fig. 9] to [Fig. 13] illustrate the main assembly steps of a foot dawn according to the invention,

[0034] - Figure [Fig. 14] illustrates the main elements of a second mode of manufacturing a paddle wheel base according to the invention,

[0035] - Figure [Fig. 15] illustrates the main elements of a third embodiment of a paddle wheel according to the invention,

[0036] - Figure [Fig. 16] illustrates the main elements of a fourth mode of manufacturing a paddle wheel base according to the invention,

[0037] - Figures [Fig. 17] to [Fig. 19] are different cross-sectional views of a fifth mode of manufacturing a paddle wheel base according to the invention,

[0038] - Figure [Fig. 20] illustrates the main elements of a sixth embodiment of a paddle wheel according to the invention,

[0039] - Figures [Fig.21] to [Fig.24] are different cross-sectional views of a seventh mode for the construction of a blade base according to the invention,

[0040] - Figures [Fig.25] and [Fig.26] are different cross-sectional views of an eighth mode of manufacturing a blade foot according to the invention, and

[0041] - Figure [Fig. 27] illustrates the main elements of a ninth mode of construction of a paddle wheel base according to the invention Detailed description

[0042] The inventors had the idea of ​​designing a new blade foot as illustrated by figure [Fig.8] not involving the dismantling of bearings when dismantling the blade.

[0043] In the figure [Fig.8], the hub includes an upper bearing 2 and a lower bearing 3, in particular roller bearings, associated with an outer metallic sleeve 13 (“outer sleeve” in English).

[0044] The blade foot 10 comprises a composite core 11, generally cylindrical in shape, with a non-through axial cavity. Depending on the embodiment, the composite core 11 has a radial constriction. The composite core 11 rests on an elastomeric stop 12, itself disposed on a flat surface of the outer metal sleeve 13. In the cross-sectional view of Figure [Fig. 8], the composite core 11 forms a fork, each of whose legs is in contact with the outer metallic sheath 13.

[0045] Two half-jaws 14 hold the composite core 11 in place within the outer metal sleeve 13. Each half-jaw 14 is shaped like a 180° sector. A different number of jaws can be used by changing the angle of each jaw. For example, three jaws at 120° or four jaws at 90° can be used. A nut 15 is screwed onto a threaded hole on the outer part of the half-jaws 14 to prevent them from opening.

[0046] Finally, a crankshaft 5 is fixed on the nut 15 in order to be able to modify the timing of the blade.

[0047] The assembly steps of this new blade foot in a blade support 4 are illustrated by figures [Fig.9] to [Fig.13].

[0048] Figure [Fig.9] is a cross-sectional view of a blade support 4 in which the bearings 2,3 and the outer metal sleeve 13 are installed.

[0049] In a first step, illustrated by the figure [Fig. 10], the elastomeric stop 12 is installed in support on the outer metallic sleeve 13.

[0050] In a second step, illustrated by Figure [Fig. 11], the blade foot is inserted into the outer metal sleeve 13. It should be noted that the blade foot comprises a composite core 11 with an external diameter substantially equal to the internal diameter of the outer metal sleeve 13. The composite core 11 is provided with a radial shoulder with respect to the axis A of the blade foot, intended to be in contact with the elastomeric stop 12 after assembly.

[0051] An internal sleeve 16 is arranged inside the composite core to reinforce its mechanical resistance.

[0052] In a third step, illustrated by the figure [Fig. 12], the half-jaws 14 are installed so that they are supported on the composite core 11 and on the outer metal sleeve 13 and so that they prevent a translation of the blade along its axis of revolution A or along a radial direction relative to the blade support.

[0053] To achieve this, each half-jaw 14 has a generally prismatic cross-section so as to penetrate into a complementary shape of the composite core 11.

[0054] More specifically, each half-jaw 14 has a profile widening from a radially internal section 14a relative to the axis A of the blade support to a radially external section 14b. The composite core 11 has a complementary section narrowing from a radially internal section relative to the axis A of the blade support to an intermediate radial section, then widening until it corresponds to the internal diameter of the outer metal sleeve 13. It should be noted that the elastomeric stop is compressed (using external tooling for example) in order to introduce a preload into the composite part of the blade after assembly and in order to obtain the assembly clearances necessary for the installation of the half-jaws 14.

[0055] Once installed, the half-jaws 14 prevent the blade root from translating relative to the blade support 4. The compression applied to the elastomeric stop by the external tooling is then released to press the half-jaws 14 against the outer sleeve 13. The preload resulting from this installation locks the composite core 11 of the blade when the engine is stopped. This prevents the blade from moving within the outer sleeve 13 in the absence of centrifugal force resulting from rotation during operation. Conversely, this preload is compensated by the centrifugal force during blade rotation. This compensation allows the blade to rotate in order to fix its variable pitch.

[0056] In a fourth step, illustrated by Figure [Fig. 13], a nut 15 is screwed onto the half-jaws 14 to prevent them from opening. It will be understood that such a nut 15 can be generalized to any means of limiting the opening of the half-jaws, such as an annular plate or a ring secured to the half-jaws 14 by means of reversible fastening means, such as screws, bolts or threaded rod cooperating with internally threaded holes provided in the half-jaws 14 and said ring or ring.

[0057] Figure [Fig. 14] illustrates an alternative embodiment in which the crown-shaped elastomeric stop 12 shown in Figure [Fig.8] is replaced by a conical elastomeric stop 12a.

[0058] To accommodate such a change in shape, the composite core is modified so as to no longer have a radial shoulder. The composite core 11 also has a conical shape cooperating with the conical elastomeric stop 12a so as to maximize the contact between them.

[0059] Similarly, the upper part of the outer metal sleeve is modified so that the flat of the outer metal sleeve 13 receiving the elastomeric stop 12 in the first embodiment illustrated by the figure [Fig.8] is replaced by a conical shoulder of the outer metal sleeve 13a coaxial with the axis A of the blade foot.

[0060] This embodiment offers the advantage of easier and more compatible integration of a composite-core foot. This embodiment also supports Péchasse E during bending loads and limits the stiffness variation at the exit of the outer metal sleeve 13a. It should be noted that Péchasse E is located between the foot and the blade. More precisely, here, between the blade and the bearing area opposite the elastomer shim.

[0061] Figure [Fig. 15] illustrates another alternative embodiment in which the jaw halves 14 of the first embodiment illustrated in Figure [Fig. 8] are replaced by jaw halves 14a having a shoulder that increases the contact area with the outer metal sleeve 13. To increase the contact area, each jaw halves 14a have an external concave shape in contact with the outer sleeve 13 on two faces thereof. Each jaw halves 14a include an internal concave shape that increases the contact area with the composite core at the radial narrowing.

[0062] Figure [Fig. 16] illustrates an alternative embodiment of the composite core 11 of the first embodiment illustrated in Figure [Fig. 8]. In this alternative embodiment, the composite core 1a has a cylindrical shape both on its outer surface and on its inner surface at the axial recess of the fork. The inner sleeve 16a is modified accordingly to conform to the inner surface of the composite core 1a.

[0063] Figures [Fig. 17] to [Fig. 19] illustrate an alternative embodiment of a blade foot in which the crankshaft 5a is integrated into the outer sleeve and in which the composite web 11b has a two-lobed section, the outer sleeve 13c being adapted in a complementary way to the composite web 11b.

[0064] Integrating the referenced crankshaft into the outer sleeve offers the advantage of reducing the number of parts and interfaces. To accommodate the integration of the crankshaft 5a, the outer sleeve 13c is modified to locally increase the available material, at the expense of the material available for the composite core 1la, at the point of insertion of the crankshaft 5a.

[0065] Figure [Fig. 17] is a cross-sectional view of the composite web 11b and the sleeve 13c along a cutting plane normal to the axis A of revolution of the blade root. A first cutting plane BB of symmetry of the lobes of the composite web 11b and a second cutting plane CC normal to the first cutting plane BB and passing through the symmetry plane of the crankshaft 5a are defined.

[0066] Figure [Fig. 18] is a cross-sectional view of the blade foot and blade support 4 along section plane BB. The elements described in previous embodiments are also present here, in particular the composite core, the elastomeric stop 12, the outer sleeve, the half-jaws 14, the nut 15, and the inner sleeve. This embodiment includes a composite core 11b with the characteristics of the outer surface of the composite core illustrated in Figure [Fig. 16], and having an internal shape that flares out in its distal part relative to the axial opening at the end of the fork. The outer sleeve 13c has a shape complementary to that of the composite core 11b, while the inner sleeve 16a conforms to the inner surface of the composite core 11b.

[0067] This embodiment further includes half-jaws 14 and a nut 15 similar to those illustrated in the figure [Fig. 16].

[0068] Figure [Fig.19] is a cross-sectional view of the blade foot and blade support 4 along the section plane CC.

[0069] As noted in the description of Figure [Fig. 18], this embodiment replicates the shape characteristics of the outer surface of the composite web illustrated in Figure [Fig. 16]. It should be noted that the outer surface of the composite web 11b is radially thinned in its lower portion opposite the lower bearing 3. This thinning corresponds to a widening of the outer sleeve 13c, facilitating, in particular, the integration of the crankshaft. This thinning also contributes to the torque transfer between the sleeve and the composite blade.

[0070] Figure [Fig. 20] illustrates an alternative embodiment of the cross-sectional view of the blade foot and blade support 4 along the section plane CC shown in Figure [Fig. 19]. In this alternative embodiment, the nut 15 is replaced by reversible fastening means 15a, such as screws or bolts of the jaw halves 14b in the outer sleeve 13c. It should be noted that the local increase in available material of the outer sleeve 13c for the integration of the crankshaft 5a also provides the material necessary for attaching the reversible fastening means 15a.

[0071] Figures [Fig.21] to [Fig.24] illustrate an alternative embodiment of a blade foot with integrated crankshaft 5a in which the composite web 11 forms four lobes instead of two lobes in the embodiment illustrated by figures [Fig. 18] to [Fig.20],

[0072] Figure [Fig.21] is a cross-sectional view of the composite core 1 and the sleeve 13d along a cutting plane normal to the axis A of the blade root. A first cutting plane BB, a second cutting plane CC and a third cutting plane DD are shown.

[0073] The first cutting plane BB is a plane of symmetry of two pairs of lobes of the composite web 1 le and a plane of symmetry of the crankshaft 5a. The second cutting plane CC is a plane of symmetry of two pairs of lobes of the composite web 1 le normal to the first cutting plane BB. The third cutting plane DD is a plane of symmetry of two opposite lobes of the composite web 1 le, forming a 45° angle with each of the planes BB and CC.

[0074] Figure [Fig. 22] is a cross-sectional view of the blade foot and blade support 4 along section plane BB. Figure [Fig. 22] includes the same elements as Figure [Fig. 17].

[0075] The cross-section of the blade foot and blade support 4 in this embodiment essentially comprises the same elements as the cross-section of the blade foot and blade support 4 illustrated in Figure [Fig. 20]. They differ from them by the replacement of nut 15 by reversible fastening means, such as screws or bolts referenced 15a.

[0076] Figure [Fig.23] is a cross-sectional view of the blade foot and blade support 4 along the section plane CC.

[0077] The cross-section of the blade foot and blade support 4 in this embodiment comprises essentially the same elements as the cross-section of the blade foot and blade support 4 illustrated in Figure [Fig. 22]. They differ from it by the absence of the crankshaft 5a.

[0078] Figure [Fig.24] is a cross-sectional view of the blade foot and blade support 4 along the cutting plane DD.

[0079] The blade foot and blade support 4 cross-section in this embodiment essentially comprises the same elements as the blade foot and blade support 4 cross-section illustrated in Figure [Fig. 19]. They differ from it by the absence of the nut 15 due to the use of reversible fastening means, such as screws or bolts referenced 15a illustrated in Figures [Fig. 22] and [Fig. 23].

[0080] Figures [Fig.25] and [Fig.26] illustrate another alternative embodiment, based on the embodiment illustrated by figures [Fig.8] to [Fig.15].

[0081] Figure [Fig. 25] is a cross-sectional view of the blade foot and blade support 4, in which they are distinguished from the blade foot and blade support 4 illustrated in Figures [Fig. 8] to [Fig. 15] by means of half-jaws 14c, 14d comprising an indentation intended to cooperate with a corresponding form provided in the outer sleeve 13e. This indentation makes it possible to limit the axial displacement of the blade in conjunction with the half-jaws 14c.

[0082] The blade foot and blade support 4 are distinguished from other embodiments by the integration of the crankshaft 5b into one of the half-jaws, referenced 14d.

[0083] Figure [Fig.26] is viewed in the axial direction of the half-jaws 14c, 14d, the half-jaw 14d comprising the crankshaft 5b.

[0084] Furthermore, each half-jaw 14c, 14d comprises an external shoulder 16 extending radially at each of its ends. The shoulder 16 of one half-jaw is designed to correspond with a shoulder 16 of the other half-jaw. Each radial shoulder 16 is further provided with a bore in a direction normal to the axis A of revolution of the blade foot, so that two adjacent shoulders 16 can be joined by reversible fastening means 16a.

[0085] Figure [Fig. 27] is a cross-sectional view of the blade foot and blade support 4, corresponding to the cross-sectional view of Figure [Fig. 17] or [Fig. 22]. A means of securing the blade 18 in case of rupture of the outer sleeve 13.

[0086] The different embodiments described above are not mutually exclusive and can be combined with each other insofar as their technical characteristics are not incompatible.

[0087] The turbocharger described above, comprising blade supports and blade feet as described above, allows for faster blade assembly and disassembly than in the prior art due to the absence of the need to disassemble the upper and lower bearings.

Claims

Demands

1. Variable pitch bladed propeller, comprising at least two blades and a rotor equipped with a hub, the hub comprising a blade support for each blade of the propeller, each blade comprising a blade foot designed to cooperate with one of said blade supports so as to maintain the blade in position in the rotor while allowing the pitch to be changed, characterized in that it comprises: a. - a blade foot comprising a composite core (11) having a generally cylindrical shape having an axis of revolution (A), the composite core (11) being provided with a non-through axial cavity, disposed in an outer sleeve (13) of the blade support also cylindrical and resting on it by means of an elastomeric pad (12), b.- a blade support (4) provided with an upper bearing (2) and a lower bearing (3) in contact with the outer sleeve (13), the blade support (4) also comprising at least two half-jaws (14) cooperating with the composite core (11) so as to prevent the blade foot from moving in a radial direction (R) relative to the axis (A) of the blade support (4), c. The composite core (11), the axial cavity and the outer sleeve (13) sharing the same axis of revolution (A) so as to be concentric.

2. Propeller according to claim 1, wherein the composite core (11) has a cylindrical shape, with or without radial narrowing.

3. Propeller according to claim 1 or 2, wherein the elastomer pad (12) is crown-shaped, the composite core (11) then comprising a radial shoulder designed to bear against a surface of the elastomer pad (12), the outer sleeve (13) comprising a flat to accommodate the elastomer pad (12).

4. Propeller according to claim 1 or 2, wherein the elastomeric buffer (12) is conical in shape, the outer sleeve (13) comprising an axial shoulder designed to support a surface of the elastomer pad (12), the composite core (11) having a conical surface opposite the elastomer pad (12).

5. Propeller according to any one of claims 1 to 4, comprising a crankshaft (5a) integrated into the outer sleeve (13) or a crankshaft (5b) integrated into a half-jaw (14d).

6. Propeller according to any one of claims 1 to 5, wherein the half-jaws (14,14b,14c,14d) have an angular sector shape so as to be in contact with the entire periphery of the blade foot, the half-jaws (14d) being provided with radial shoulders (17) at their ends, the shoulder of one half-jaw being secured to the shoulder of an adjacent half-jaw by means of reversible securing means (17a), such as screws and threaded holes.

7. Propeller according to any one of claims 1 to 6, including means of securing (15,15a) preventing the opening of the half-jaws (14).

8. Propeller according to claim 7, wherein the fastening means (15) are a nut and a corresponding thread provided on the outer surface of the half-jaws (14), the nut being screwed onto the thread of the half-jaws (14) in order to prevent them from opening.

9. Propeller according to claim 8, wherein the fastening means (15a) are a plurality of screws or bolts and a plurality of corresponding threaded holes provided in the outer sleeve (13) of the blade support (4), the plurality of screws or bolts being screwed into the plurality of threaded holes in order to prevent the opening of the jaw halves (13).

10. Propeller according to any one of claims 1 to 9, wherein a blade comprises an inner sleeve (16,16a) disposed in the axial cavity of the composite core (11,11a, 11b, 11e) and an axial reinforcement (18) disposed in the inner sleeve (16,16a).

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