FR3050718A1 - AIRCRAFT TURBOMACHINE PROPELLER COMPRISING SIMPLIFY RADIATION RETENTION MEANS FOR PROPELLER BLADE - Google Patents

Abstract

In order to simplify the design of an aircraft turbomachine propeller, while reinforcing its safety function with respect to the retention of its blade feet (54), the invention provides a propeller which, in its configuration assembly, has a hub (40) with a housing cavity (80) equipped with a shaft (90) for retention of a blade (50), this axis passing through a housing hole (92) in the blade root ( 54), and being arranged at a distance from a radial abutment element (76) forming a removable bottom of a hollow member (46) delimiting the cavity (80).

Description

AIRCRAFT PROPELLER PROPELLER COMPRISING SIMPLIFY MEANS FOR RADIAL RETENTION OF PROPELLER BLADE

DESCRIPTION

TECHNICAL AREA

The present invention relates to a propeller for aircraft turbomachine. It more specifically concerns the management of the radial retention of the propeller blades, in particular the management of the safety function in the event of a failure, also known as the "Fail Safe" function. The invention is preferably applicable to turbomachines comprising a pair of non-careened contrarotating propellers, these turbomachines being also called "Open Rotor", or "CROR" (English "Contra Rotative Open Rotor"). Nevertheless, the application of the invention can be extended to any other turbomachine comprising one or more propellers, such as turboprops.

STATE OF THE PRIOR ART

Aircraft turbomachine propellers have already been the subject of numerous developments, particularly as regards the management of the safety function in the event of a blade failure. This function known as "Fail Safe" makes it possible to ensure that, following a failure of the main retention device of the blade, it can always be retained radially relative to the hub of the propeller. Designs making it possible to provide such a function are for example disclosed in the documents FR 2 943 984 and FR 2 943 985. Nevertheless, there is a need to optimize the existing solutions to meet the ever higher requirements in terms of Fail function. Safe, while simplifying design to reduce costs.

STATEMENT OF THE INVENTION

To at least partially meet this need, the invention relates to a propeller for aircraft turbomachine comprising: a hub centered on an axis of rotation of the propeller; a plurality of propeller blades intended to be piloted in incidence and each having a blade root, and, associated with at least one of said blades: a main device for retaining the blade in a radial direction thereof; a hollow member integral with the hub and defining a housing cavity traversed by the blade root, the hollow member having a side wall.

According to the invention, in an assembled configuration of the helix, said housing cavity is equipped with a secondary retention element of the blade in the radial direction thereof, said secondary retention element passing through a housing orifice in the blade root, and being arranged, in the radial direction, away from a radial abutment member forming a bottom of the hollow member, the radial abutment member being traversed by the blade root and removably mounted on the side wall of the hollow organ. The invention thus has a clever design which makes it possible to obtain a high performance Fail Safe function with respect to the risk of blade foot loss, while being based on a simple design, comprising a limited number of elements. It therefore offers a very satisfactory solution in terms of safety and costs. The invention preferably has at least one of the following optional features, taken singly or in combination. The secondary retention element is an axis housed in the housing cavity and projecting from the blade root, the axis preferably being of circular section. The secondary retention element is held in said housing hole by means of locking means in translation, preferably with the aid of one or more circlips and / or one or more pins. The propeller comprises a blade-angle setting device adapted to vary at least one of the blades in incidence by rotating it along a radial axis of said blade, and said main retention device couples the blade root to the device. stalling in incidence.

The device for guiding the rotation of the blade root is screwed into the housing cavity. Other types of assembly can nevertheless be envisaged, without departing from the scope of the invention. It may for example be the use of separate screwed elements, ensuring the attachment of the device in the housing cavity. The radial abutment member is mounted with screws on the side wall of the hollow member. Alternatively, the radial abutment element could be mounted screwed directly to this side wall, in the manner of a nut.

Said housing cavity defined by the hollow member has a cylindrical shape of circular section.

The blade root protrudes beyond the radial abutment member, outside the hollow member.

Said hub comprises a main ring, pierced with at least one opening from which the hollow member extends radially, preferably outwardly.

The main retention device of the blade ensures a coupling between the wedging device in incidence and an inner radial end of the blade root, said inner radial end being preferably arranged radially inward relative to the hub.

The main device for retaining the blade is an axis, preferably of circular section.

The device for guiding the rotation of the blade root is a rolling bearing. The secondary retention element is cylindrical and / or parallel to the radial abutment element. The propeller comprises a drive shaft in rotation centered on the axis of rotation, and around which is arranged the wedging device in incidence of the blade. The invention also relates to an aircraft turbomachine comprising a helix as described above, said turbomachine preferably comprising a doublet receiver non-keeled contra rotating propellers. The invention finally relates to an aircraft comprising at least one such turbomachine, the latter preferably being attached to the rear part of the fuselage. Alternatively, it can be reported on a wing of the aircraft or on a more advanced portion of its fuselage, without departing from the scope of the invention.

Finally, the subject of the invention is a method of assembling such a helix, comprising the following successive steps: introduction of the blade root through the radial abutment element detached from the hollow member; - Mounting the secondary retention element in the housing hole, maintaining the radial abutment member radially outwardly relative to the secondary retention element; introduction into the cavity of housing, in the radial direction inwards, of the blade root equipped with the second retention element; and - mechanical coupling between the blade root and the main device for retaining the blade in the radial direction, and mounting the radial abutment element on the side wall of the hollow member, so as to bring the propeller into its assembled configuration. Other advantages and features of the invention will become apparent in the detailed non-limiting description below.

BRIEF DESCRIPTION OF THE DRAWINGS

This description will be made with reference to the appended drawings among which; - Figure 1 shows a schematic perspective view of an aircraft comprising turbomachines according to the invention; FIG. 2 represents a simplified perspective view of a turbomachine according to a preferred embodiment of the invention; - Figure 3 shows a perspective view of a portion of a propeller equipping the turbomachine shown in the previous figure; FIG. 4 represents a more detailed enlarged view of a portion of the helix shown in the previous figure; FIG. 5 represents an exploded view of the portion of the helix shown in the preceding figure; FIG. 6 is a cross-sectional view of the helix shown in the preceding figures; and - Figures 7a to 7d illustrate the steps of a method of assembling the helix, according to a preferred embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring firstly to Figure 1, there is shown an aircraft 100 comprising one or more engine sets 1. More specifically, the aircraft comprises two sets 1 each reported in the rear portion of a fuselage 102 of the aircraft. The fixing of each engine assembly 1 on the fuselage 102 is carried out in a conventional manner, using a mounting pylon 104 or EMS (Engine Mounting Structure).

Each engine assembly 1 comprises a turbomachine 10 according to the invention, surrounded by a nacelle 11.

As can be seen in FIGS. 1 and 2, the turbine engine 10 is of the Open Rotor type in Pusher mode, that is to say that it comprises a gas generator as well as a receiver with a pair of counter-rotating propellers. -carenes, this receiver being arranged back with respect to the gas generator.

Throughout the following description, by convention, the direction X corresponds to the longitudinal direction of the motor assembly 1, which is also comparable to the longitudinal direction of the turbomachine 10 and this set 1. This direction X is parallel to a longitudinal axis 5 of the turbomachine 10. On the other hand, the direction Y corresponds to the direction transversely oriented relative to the engine assembly 1 and also comparable to the transverse direction of the turbomachine 10, while the Z direction corresponds to vertical direction or height. These three directions X, Y and Z are orthogonal to each other and form a direct trihedron. On the other hand, the terms "upstream" and "downstream" are to be considered with respect to a main direction of flow of the gases through the turbomachines 10, this direction being shown schematically by the arrow 19.

Overall, each turbomachine 10 comprises from upstream to downstream a low pressure compressor, a high pressure compressor, a combustion chamber, a high pressure turbine and a low pressure turbine. The low pressure compressor and the low pressure turbine are connected by a low pressure shaft (not shown), while the high pressure compressor and the high pressure turbine are connected by a high pressure shaft (not shown) to form together a gas generator. . All these elements are surrounded by a motor housing 26 centered on the axis 5.

Downstream of the low-pressure turbine, there is provided a counter-rotating type pair of receivers, namely an upstream propeller 32 and a downstream propeller 34. Although this has not been shown, the propellers are driven via a free power turbine or an epicyclic gearbox. At the front of the receiver 30, the turbine engine 10 is surrounded by the nacelle 11 which comprises an air inlet 36, extended towards the rear by movable covers 38 giving access to the equipment of the turbomachine, for maintenance operations. One of the peculiarities of the invention lies in the design of the propellers 32, 34. Their design being identical or similar, only that of the upstream propeller 32 will now be detailed below, with reference to FIGS. .

First of all with reference to FIG. 3, the propeller 32 comprises a hub 40 centered on the axis of rotation of the helix, corresponding to the axis 5. This hub 40 comprises a main ring 42 centered on the 5, pierced with several openings 44 spaced circumferentially from each other, and oriented radially relative to this axis 5. The hub 40 also comprises hollow members 46 associated with the openings 44 and extending radially outwardly from the main ring 42. Each hollow member 46 is intended for receiving a blade 50 of the propeller, as will be explained in detail below. In addition, the helix comprises an outer cowling 52 shown only schematically in FIG. 3, this cowling 52 being centered on the axis 5 and arranged around the hollow members 46. In a conventional manner, the outer surface of this cowling 52 is intended to to be married by the air circulating around the turbomachine, before reaching the blades of the propellers. The propeller 32 thus comprises a plurality of blades 50, provided in a number for example between eight and twelve. Each blade 50 is preferably arranged in an identical or similar manner within the helix. Therefore, only the arrangement of a blade 50 will now be described with reference to FIGS. 4 to 6.

The blade 50 conventionally comprises a foot 54 carrying a blade 56. These two elements 54, 56 follow one another in the radial direction of the blade, identified by reference 60 in the figures. It is noted that conventionally, the radial direction 60 of the blade corresponds to the direction of its length, from its foot to its head. This radial direction 60 also corresponds to that of the axis about which the blade is intended to be driven in incidence, as will be explained below.

The blade 50 may be made conventionally, for example by being entirely made of composite material.

The blade root 54 has a cylindrical shape of circular section, with an axis 62 parallel to the radial direction. One of its ends is connected to the blade 56, while the other end, namely its inner radial end 64, is arranged radially inwardly relative to the main ring 42 of the hub 40. This end 64 is mechanically coupled to a device 66 for wedging in incidence of the blade, of conventional design and known to those skilled in the art. In this respect, it is indicated that the propeller 32 comprises a rotary drive shaft 68 centered on the axis 5, and around which the bearing wedging device 66 is arranged. In a known manner, the displacement in rotation of the device 66 relative to the drive shaft 68, along the axis 5, makes it possible to cause an axial relative displacement between these two elements 66, 68, which then causes pivoting of the blade root 54 along its axis 62. The mechanical coupling between the end 64 of the foot 54 and the device 66 for wedging in incidence is achieved by an axis 70, forming a main device 70 for radial retention of the blade 50. This axis 70 passes through the end of blade 64 and a yoke 72 located at the end of the device 66 wedging incidence. It thus makes it possible to retain the blade 50 in the radial direction 60, preventing it from moving radially outwards relative to the hub 40, under the effect of the centrifugal force observed during operation. The hollow member 46 extends along the axis 62, on which it is centered. It remains open at its axial end located at the opening 44 in the main ring 42, while it is closed at its opposite end. This is formed by a radial abutment element 76, also called the closure wall, which takes the form of a plate constituting the bottom of the hollow member 46. The radial abutment element 76, which will subsequently be called closure wall 76, is traversed by the blade root 54 and arranged orthogonally to the same foot. The hollow member 46 also has a side wall 78 centered on the axis 62, and delimiting with the closure wall 76 a housing cavity 80 opening on the opening 44. The side wall 78 is cylindrical, preferably of cross section. ring shape centered on the axis 62. The cavity 80 and has a cylindrical shape of circular section, of diameter Dl. The hollow member 46 is made by means of different elements that are attached to one another, in particular with the closure wall 76 removably mounted on the outer radial end of the side wall 78. preferably by means of radially oriented screws 94 passing through fixing orifices located at the periphery of the closure wall 76, and screwed into corresponding threaded orifices 95 of the side wall 78.

The housing cavity 80 is traversed by the blade root 54, which extends beyond the opening 44 in the radially inward direction. The propeller 32 also comprises a device 82 for guiding the blade root 54 in rotation, this device preferably taking the form of a rolling bearing.

This guide device 82 is housed in the housing cavity 80, also being centered on the axis 62, and arranged between a side wall 78 and the blade root 54. Its outer diameter is substantially identical to that of the diameter DI of the housing cavity 80. Furthermore, the outer surface of the guiding device 82 has an external thread 84 for assembling this device 82 by screwing on a corresponding thread 86 made inside the cavity 80, on the inner surface of the side wall 78.

In the assembled configuration of the helix 32 as shown in FIGS. 4 and 6, the housing cavity 80 is equipped with another axis 90 forming a radial retention secondary element of the blade 50. This axis 90, or axis retention, allows to perform a safety function called Fail Safe vis-à-vis the risk of loss of the blade foot.

More specifically, the axis 90 is cylindrical with a circular cross-section, and passes through a correspondingly shaped housing orifice 92 formed in the blade root 54. A tight fit can be provided so that the axis 90 can be retained by friction through the orifice 92. Nevertheless, this tight fit is not necessary, since in operation, the axis 90 is in any case intended to be retained inside the hollow member 46. way, it is preferentially provided one or more circlips cooperating with the axis 90 on either side of the blade root 54, so as to maintain this axis 90 in its associated orifice 92. Alternatively, these circlips can be replaced by pins 90 through the secondary retention axis 90. The axis 90 preferably projects from either side of the housing orifice 92, and therefore has a length greater than the outside diameter of the blade root. Its length L1 is slightly smaller than the diameter DI of the cavity 80, so that this axis 90 is devoid of contact with the inner surface of the side wall 78 of the hollow member 46.

The parts of the axis 90 projecting from the blade root are arranged at a distance from the closure wall 76 in the radial direction 60, so as to avoid contact. The axis 90 is preferably parallel to the closure wall 76. Likewise, the axis 90 is situated at a radial distance from the guide device 82, which does not prevent or inhibit the rotation of the blade root 54.

In this way, the axis 90 is waiting, namely that it is only intended to come into contact with the closure wall 76 in the event of failure of the main axis 70, for example in case of rupture of the latter . In such a case, the main axis 70 is effectively no longer able to retain radially blade root 54, which implies that the radial clearance between the closure wall 76 and the axis 90 is quickly consumed under the effect of the centrifugal force applying to the blade 50 of the rotating propeller. Once the game is fully consumed, the contact between these elements 76, 90 satisfactorily fulfills the function of radial retention of the blade root 54. For this reason, the axis 90 is considered to fulfill the function Fail Safe vis-à-vis a failure occurring on the blade root 54.

Referring now to FIGS. 7a to 7d, the steps of a method of assembling the helix according to a preferred embodiment of the invention will be described.

First, the blade root 54 is introduced through the closure wall 76, which at this stage is not mounted on the hollow member. This step is shown in Figure 7a. It is followed by a step of mounting the axis 90 in the housing hole 92 of the blade root 54. This assembly is performed by maintaining the closure wall 76 radially outwardly relative to the axis 90 To complete this assembly, the circlips 96 are positioned around the axis 90, as shown in Figure 7b.

Then, it is proceeded to the introduction of the blade root 54 equipped with the axis 90, within the housing cavity 80 defined by the hollow member 46. This introduction shown schematically in Figures 7c and 7d is achieved by moving the blade in the radial inward direction, relative to the hollow member 46. Once completed, this introduction step is followed on the one hand by the mechanical coupling of the blade root 54 to the axis 70 and to the device 66 for wedging the blade in incidence, and secondly for mounting the closure wall 76 on the side wall 78 of the hollow member, so as to bring the helix into its assembled configuration shown in particular on Figures 4 and 6.

Of course, various modifications may be made by those skilled in the art to the invention which has just been described, solely by way of non-limiting examples.

Claims (15)

A propeller (32, 34) for an aircraft turbomachine (10) comprising: a hub (40) centered on an axis of rotation (5) of the propeller; a plurality of propeller blades (50) to be driven in incidence and each having a blade root (54), and associated with at least one of said blades: a main blade retention device (70) (50) in a radial direction (60) thereof; a hollow member (46) integral with the hub (40) and defining a housing cavity (80) traversed by the blade root (54), the hollow member (46) having a side wall (78); characterized in that in an assembled configuration of the helix, said housing cavity (80) is provided with a secondary retention element (90) of the blade in the radial direction thereof, said secondary retention element passing through a housing hole (92) in the blade root (54), and being arranged, in the radial direction (60), away from a radial abutment member (76) forming a bottom of the hollow member (46); ), the radial abutment member (76) being traversed by the blade root (54) and removably mounted on the side wall (78) of the hollow member (46). 2. Propeller according to claim 1, characterized in that the secondary retention element is an axis (90) housed in the housing cavity (80) and projecting from the blade root (54), the axis (90). preferably being of circular section. 3. Propeller according to claim 1 or claim 2, characterized in that the secondary retention element (90) is held in said housing opening (92) by means of translation locking means, preferably at least one using one or more circlips and / or one or more pins. 4. Propeller according to any one of the preceding claims, characterized in that it comprises a device (66) for wedging blade incidence designed to vary at least one of the blades (50) in incidence by rotating it in a manner radial axis (62) of said blade, and in that said main retention device (70) couples the blade root (54) to the incidence wedging device (66). 5. Propeller according to any one of the preceding claims, characterized in that the radial stop element (76) is mounted by means of screws (94) on the side wall (78) of the hollow member (46). ). 6. Propeller according to any one of the preceding claims, characterized in that said housing cavity (80) defined by the hollow member (46) has a cylindrical shape of circular section. 7. Propeller according to the preceding claim, characterized in that the blade root (54) protrudes beyond the radial abutment element (76), outside the hollow member (46). 8. Propeller according to any one of the preceding claims, characterized in that said hub (40) comprises a main ring (42), pierced with at least one opening (44) from which the hollow member (46) extends radially, preferably outwards. 9. Propeller according to any one of the preceding claims combined with claim 4, characterized in that the main device (70) retaining the blade provides a coupling between the device (66) wedging incidence and an inner radial end (64) of the blade root (54), said inner radial end (64) being preferably arranged radially inward relative to the hub (40). 10. Propeller according to any one of the preceding claims, characterized in that the main device for retaining the blade is an axis (70), preferably of circular section. 11. Propeller according to any one of the preceding claims, characterized in that the secondary retention element (90) is cylindrical and / or parallel to the radial abutment element (76). 12. Propeller according to any one of the preceding claims combined with claim 4, characterized in that it comprises a shaft (68) for driving in rotation centered on the axis of rotation (5), and around which is arranged the device (66) for wedging in incidence of the blade. 13. An aircraft turbomachine (10) comprising a propeller (32, 34) according to any one of the preceding claims, said turbomachine preferably comprising a doublet receiver of non-careened contra-rotating propellers (32, 34). 14. Aircraft (100) comprising at least one turbomachine (10) according to the preceding claim. 15. A method of assembling a propeller (32, 34) according to any one of claims 1 to 12, characterized in that it comprises the following successive steps: - introduction of the blade root (54) through the radial abutment member (76) detached from the hollow member (46); - mounting the secondary retention element (90) in the housing opening (92), keeping the radial abutment element (76) radially outwardly relative to the secondary retention element (90) ; - introducing within the housing cavity (80), in the radially inward direction, the blade root (54) equipped with the secondary retention element (90); and - mechanical coupling between the blade root (54) and the main device (70) for retaining the blade in the radial direction (60), and mounting the radial abutment element (76) on the lateral wall (78). ) of the hollow member (46) so as to bring the helix into its assembled configuration.