Variable-pitch blade propeller with easy-disassembly blade support

Abstract

The invention relates to a variable-pitch blade propeller comprising at least two blades and a rotor provided with a hub, the hub comprising a blade support for each blade of the propeller, each blade comprising a blade root designed so as to be able to co-operate with one of the blade supports in order to keep the blade in position in the rotor while allowing the pitch to be changed, wherein the propeller further comprises: a blade root comprising a composite core (11) having a generally cylindrical shape, having an axis of revolution (A), and being arranged in an outer sheath (13) of the blade support, wherein the sheath rests on the composite core via an elastomer pad (12), and a blade support (4) provided with an upper bearing (2) and a lower bearing (3) in contact with the outer sheath (13), wherein the blade support (4) further comprises at least two half-jaws (14) co-operating with the composite core (11) in order to prevent the movement of the blade root in a direction along the axis (A).

Description

[0001]DESCRIPTION TITLE: Variable-pitch bladed propeller with blade support featuring easy disassembly. Technical Field The invention relates to unfaired propellers, and more specifically to such variable-pitch bladed propellers. Prior Techniques 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, but can be extended to unfaired engines known as "open rotor" or "unducted fan" engines. The propeller comprises a rotor element fixed to the engine shaft and comprising several cylindrical housings distributed around its periphery, each equipped with a blade support. Each blade of the propeller comprises 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. 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. The supports and the internal portions 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 suitable means.in order to adjust the angular pitch of the blades. The mounting of a propeller blade according to the prior art is illustrated in Figure [Fig 1]. The rotor includes a hub with blade supports arranged in openings, and in each of these openings is a blade root. Figure [Fig 1] illustrates the mounting of the upper bearing of the blade root. Thus, the blade root 1 includes an upper bearing 2 comprising an inner ring 2a1, 2a2, rollers 2b1, 2b2, and an outer ring 2c. The inner ring 2a1, 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 2b1, 2b2 after they have been installed on the inner ring 2a. The rotor includes a hub provided with blade supports 4 arranged in openings 4a, and in each of which a blade foot 1 is inserted,as illustrated in Figures [Fig. 2] and [Fig. 3]. Note that the outer ring 3a of the lower bearing 3 is pre-positioned around 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. Figure [Fig. 4] illustrates the installation of the inner ring 3c1, 3c2 of the lower bearing 3 onto the base of the blade foot. As with the inner ring 2a1, 2a2, the inner ring 3c1, 3c2 is in two parts to allow its installation while the sleeve is supported below the lower bearing. Figure [Fig 5] illustrates the installation of the rollers 3b of the lower bearing 3 on the inner ring 3c1, 3c2 and the screwing of the outer ring 2c of the upper bearing 2 into an upper nut 3d of the blade foot. Figure [Fig 6] shows the upward movement of the blade foot in the blade support 4, causing the movement of the inner ring 3c1.3c2 until contact with the rollers 3b of the lower bearing 3. Figure [Fig 7] shows the installation of a crankshaft 5 on the blade base to control the angular positioning of the blade. The major drawback of the current solution lies in the long disassembly / reassembly time due to the number of parts involved, the sequence of steps to be followed, and the risks of damage related to handling numerous blade components, particularly during bearing removal. Another drawback is the need to remove the bearings to disassemble the blade. From the prior art, we also know of document EP0324617A2 describing a blade fixing system. Such a system also involves removing bearings to disassemble the blade. It therefore does not resolve the drawbacks identified above. The technical problem solved by the present invention is to remedy the drawbacks of the prior art,particularly the need to dismantle bearings to remove a blade. Description of the invention 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: - a blade root comprising a composite core having a generally cylindrical shape with an axis of revolution, the composite core being provided with a non-through axial cavity, disposed in an outer sleeve of the blade support, also cylindrical, and resting on it by means of an elastomeric pad, - a blade support equipped with an upper bearing and a lower bearing in contact with the outer sleeve,The blade support also includes at least two half-jaws cooperating with the composite core so as to prevent the blade root from moving radially relative to the axis of the blade support; the composite core, the axial cavity, and the outer sleeve share the same axis of revolution so as to be concentric. The composite core may be cylindrical, with or without radial narrowing. The elastomer pad may be crown-shaped, the composite core then including a radial shoulder designed to bear against a surface of the elastomer pad, the outer sleeve including a flat to accommodate the elastomer pad. The elastomer pad may be conical, the outer sleeve including an axial shoulder designed to support a surface of the elastomer pad.The composite core has a conical surface facing the elastomer pad. The propeller may include a crankshaft integrated into the outer sleeve or a crankshaft integrated into a half-jaw. The half-jaws may have an angular sector shape so as to be in contact with the entire periphery of the blade root, the half-jaws being provided with radial shoulders at their ends, the shoulder of one half-jaw being secured to the shoulder of an adjacent half-jaw by means of reversible fastening means, such as screws and threaded holes. The propeller may include fastening means preventing the half-jaws from opening. The fastening means may be a nut and a corresponding thread provided on the outer surface of the half-jaws.The nut is screwed onto the threads of the jaw halves to prevent them from opening. The fastening means may consist of a plurality of screws or bolts and 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 to prevent the jaw halves from opening. A blade may comprise 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. 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: - Figures [Fig 1] to [Fig 7] illustrate the assembly steps of a blade of an "open fan" turboprop propeller according to the prior art.- Figure [Fig 8] illustrates the main elements of a blade foot according to the invention, - Figures [Fig 9] to [Fig 13] illustrate the main assembly steps of a blade foot according to the invention, - Figure [Fig 14] illustrates the main elements of a second embodiment of a blade foot according to the invention, - Figure [Fig 15] illustrates the main elements of a third embodiment of a blade foot according to the invention, - Figure [Fig 16] illustrates the main elements of a fourth embodiment of a blade foot according to the invention, - Figures [Fig 17] to [Fig 19] are different cross-sectional views of a fifth embodiment of a blade foot according to the invention, - Figure [Fig 20] illustrates the main elements of a sixth embodiment of a blade foot according to the invention, - Figures [Fig 21] to [Fig 24] are different cross-sectional views of a seventh embodiment of a blade foot according to the invention,Figures [Fig 25] and [Fig 26] are different cross-sectional views of an eighth embodiment of a blade foot according to the invention, and Figure [Fig 27] illustrates the main elements of a ninth embodiment of a blade foot according to the invention. Detailed Description: The inventors conceived the idea of ​​designing a new blade foot, as illustrated in Figure [Fig 8], which does not involve the disassembly of bearings when disassembling the blade. In Figure [Fig 8], the hub comprises an upper bearing 2 and a lower bearing 3, in particular roller bearings, associated with an outer metal sleeve 13. The blade foot 10 comprises a composite core 11, generally cylindrical in shape, with a non-through axial cavity at one end. According to the embodiments, the composite core 11 has a radial constriction. The composite core 11 rests on an elastomeric stop 12,The composite web 11 is itself positioned on a flat surface of the outer metal sleeve 13. In the cross-sectional view of Figure [Fig 8], the composite web 11 forms a fork, each leg of which is in contact with the outer metal sleeve 13. Two half-jaws 14 hold the composite web 11 in place within the outer metal sleeve 13. Each half-jaw 14 is a 180° sector. A different number of jaws can be used by modifying 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. Finally, a crankshaft 5 is fixed to the nut 15 to allow adjustment of the blade's position. The assembly steps for this new blade foot in a blade support 4 are illustrated in Figures [Fig 9] to [Fig 13]. 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. In a first step, illustrated by Figure [Fig 10], the elastomeric thrust bearing 12 is installed against the outer metal sleeve 13. In a second step, illustrated by Figure [Fig 11], the blade root is inserted into the outer metal sleeve 13. It should be noted that the blade root 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 has a radial shoulder with respect to the axis A of the blade root, intended to be in contact with the elastomeric thrust bearing 12 after assembly. An internal sleeve 16 is arranged inside the composite core to reinforce its mechanical strength. In a third step, illustrated by Figure [Fig 12],The half-jaws 14 are installed so that they bear on the composite web 11 and on the outer metal sleeve 13, and so that they prevent translation of the blade along its axis of revolution A or in a radial direction relative to the blade support. To achieve this, each half-jaw 14 has a generally prismatic cross-section so as to fit into a complementary shape of the composite web 11. More precisely, 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 web 11 has a complementary cross-section narrowing from a radially internal section relative to the axis A of the blade support to a radially intermediate section.then widening until it matches the internal diameter of the outer metal sleeve 13. It should be noted that the elastomeric stop is compressed (using an external tool, 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. Once installed, the half-jaws 14 prevent the translation of the blade root relative to the blade support 4. The compression applied to the elastomeric stop by the external tooling is then released in order to press the half-jaws 14 against the outer sleeve 13. The preload resulting from such an installation makes it possible to lock 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 the rotation of the blade. This compensation allows the blade to rotate in order to fix its variable pitch. In a fourth step, illustrated in Figure [Fig 13], a nut 15 is screwed onto the jaw halves 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 jaw halves, such as an annular plate or a ring secured to the jaw halves 14 by means of reversible fastening means, such as screws, bolts, or threaded rods cooperating with internally threaded holes provided in the jaw halves 14 and said ring or ring. 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. 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 thrust bearing 12a in order to maximize the contact between them. Similarly, the upper part of the outer metal sleeve is modified so that the flat of the outer metal sleeve 13 receiving the elastomeric thrust bearing 12 in the first embodiment illustrated in Figure [Fig 8] is replaced by a conical shoulder of the outer metal sleeve 13a coaxial with the axis A of the blade root. This embodiment has the advantage of easier and more compatible integration of a root with a composite core. This embodiment also has the effect of supporting the strut E during bending loads and limiting the variation in stiffness at the exit of the outer metal sleeve 13a. It should be noted that the strut E is located between the root and the blade. More precisely here,between the blade and the bearing area opposite the elastomer wedge. Figure [Fig 15] illustrates another alternative embodiment in which the half-jaws 14 of the first embodiment illustrated by Figure [Fig 8] are replaced by half-jaws 14a having a shoulder increasing the contact area with the outer metal sleeve 13. In order to increase the contact area, each half-jaw 14a has an external concave shape in contact with the outer sleeve 13 on two faces thereof. Each half-jaw 14a includes an internal concave shape allowing the contact area with the composite core at the radial narrowing to be increased. Figure [Fig 16] illustrates an alternative embodiment of the composite core 11 of the first embodiment illustrated by Figure [Fig 8]. In this alternative embodiment,The composite web 11a has a cylindrical shape both on the outer surface of the composite web 11a and on the inner surface at the axial recess of the fork. The inner sleeve 16a is modified accordingly to fit the inner surface of the composite web 11a. Figures [Fig 17] to [Fig 19] illustrate an alternative embodiment of a blade base in which the crankshaft 5a is integrated into the outer sleeve and in which the composite web 11b has a two-lobed cross-section, the outer sleeve 13c being adapted in a complementary manner to the composite web 11b. Integrating the crankshaft into the outer sleeve has the advantage of reducing the number of parts and interfaces. In order 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 11a,at the crankshaft insertion point 5a. Figure [Fig 17] is a cross-sectional view of the composite web 11bet of 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. Figure [Fig 18] is a cross-sectional view of the blade root and the blade support 4 along the cutting plane BB. The elements described in the previous embodiments are also present here, in particular the composite web, the elastomeric thrust bearing 12, the outer sleeve, the half-jaws 14, the nut 15, and the inner sleeve. This embodiment includes a composite core 11b reproducing the characteristics of the external surface of the composite core shown 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 the shape of the composite core 11b, while the inner sleeve 16a conforms to the internal surface of the composite core 11b. This embodiment also includes half-jaws 14 and a nut 15 similar to those illustrated in the figure, [Fig 16].Figure [Fig 19] is a cross-sectional view of the blade root and blade support 4 along the cutting plane CC. As noted in the description of Figure [Fig 18], this embodiment replicates the form 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 part 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. Figure [Fig 20] illustrates an alternative embodiment of the cross-sectional view of the blade root and blade support 4 along the cutting plane CC as 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 half-jaws 14b in the outer sleeve 13c. It is noted that the local increase in available material in the outer sleeve 13c for the integration of the crankshaft 5a also provides the material necessary for attaching the reversible fastening means 15a. Figures [Fig 21] to [Fig 24] illustrate an alternative embodiment of a blade root with an 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]. Figure [Fig 21] is a cross-sectional view of the composite web 11c 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 C-C, and a third cutting plane DD are shown.The first section plane BB is a plane of symmetry of two pairs of lobes of the composite core 11c and a plane of symmetry of the crankshaft 5a. The second section plane CC is a plane of symmetry of two pairs of lobes of the composite core 11c normal to the first section plane BB. The third section plane DD is a plane of symmetry of two opposite lobes of the composite core 11c, forming a 45° angle with each of the BB and CC planes. Figure [Fig 22] is a cross-sectional view of the blade root and blade support 4 along section plane BB. Figure [Fig 22] includes the same elements as Figure [Fig 17]. The section of the blade root and blade support 4 in this embodiment essentially includes the same elements as the section of the blade root and blade support 4 illustrated in Figure [Fig 20]. They differ from them by the replacement of nut 15 with reversible fastening means, such as screws or bolts referenced 15a.Figure [Fig 23] is a cross-sectional view of the blade foot and blade support 4 along section plane CC. The section of the blade foot and blade support 4 in this embodiment essentially comprises the same elements as the section of the blade foot and blade support 4 illustrated in Figure [Fig 22]. They differ in that they are distinguished by the absence of the crankshaft 5a. Figure [Fig 24] is a cross-sectional view of the blade foot and blade support 4 along section plane DD. The section of the blade foot and blade support 4 in this embodiment essentially comprises the same elements as the section of the blade foot and blade support 4 illustrated in Figure [Fig 19]. They are distinguished by the absence of the nut 15 due to the use of reversible fastening means, such as screws or bolts referenced 15a il illustrated in figures [Fig 22] and [Fig 23].Figures [Fig 25] and [Fig 26] illustrate another alternative embodiment, based on embodiment 11 illustrated by figures [Fig 8] to [Fig 15]. Figure [Fig 25] is a cross-sectional view of the blade foot and blade support 4, in which they differ 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 formed in the external sleeve 13e. This indentation allows the axial displacement of the blade to be limited in conjunction with the half-jaws 14c. 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. Figure [Fig 26] is seen in the axial direction of the half-jaws 14c,14d, the half-jaw 14d comprising the crankshaft 5b.Furthermore, each half-jaw 14c, 14d includes an external shoulder 16 extending radially from 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 also 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. Figure [Fig 27] is a cross-sectional view of the blade foot and the blade support 4, corresponding to the cross-sectional view in Figure [Fig 17] or [Fig 22]. A means of securing the blade 18 in case of rupture of the outer sleeve 13. The different embodiments described above are not mutually exclusive and can be combined with each other insofar as their technical characteristics are not incompatible.The turbocharger described above, including 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

CLAIMS 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 so as to be able 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 an axial cavity, disposed in an outer sleeve (13) of the blade support also cylindrical and resting on it by means of an elastomeric buffer (12), b.- a blade support (4) having a shape of revolution about the axis (A) and 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 root from moving in a direction along the axis (A). 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 in the shape of a crown, 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 receive the elastomer pad (12).4.Propeller according to claim 1 or 2, wherein the elastomer pad (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) comprising 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 jaw halves (14, 14b, 14c, 14d) have an angular sector shape so as to be in contact with the entire periphery of the blade root, the jaw halves (14d) being provided with radial shoulders (17) at their ends, the shoulder of one jaw halves being secured to the shoulder of an adjacent jaw halves by means of reversible fastening means (17a), such as screws and threaded holes. 7.A propeller according to any one of claims 1 to 6, comprising fastening means (15, 15a) preventing the opening of the jaw halves (14).

8. A propeller according to claim 7, wherein the fastening means (15) are a nut and a corresponding thread provided on the outer surface of the jaw halves (14), the nut being screwed onto the thread of the jaw halves (14) to prevent their opening.

9. A 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 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,11c) and an axial reinforcement (18) disposed in the inner sleeve (16,16a).

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