Aircraft turbine engine including variable pitch propeller blades

Abstract

The invention relates to an assembly comprising a propeller blade (10) and a pitch adjustment system (34) for setting the pitch of the blade (10), wherein the root (14) of the blade (10) has a bulb (32) and the pitch adjustment system (34) for setting the pitch of the blade (10) comprises: - a cup (58) having an upper opening (58c); - a retaining ring (82) extending around the bulb (32), the retaining ring being at least limited in axial movement relative to the cup (58) towards the opening (58c) and having a bearing face (84) to hinder axial movement of the root (14) towards the opening (58c); the pitch adjustment system (34) being characterized in that it further comprises a lower seat (88) by which the root (14) is engaged with the cup (58), the seat (88) and / or the retaining ring (82) being mounted so as to be axially translatable relative to the cup (58) by at least one clamping mechanism (90).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aircraft turbine engines, in particular to the propulsive propellers of these turbine engines comprising variable-pitch blades. BACKGROUND

[0002] Aircraft turbine engine propellers can be ducted (for example in the case of fans) or unducted (for example in the case of open-rotor architectures).

[0003] The propeller comprises blades which can be variable-pitch. The turbine engine therefore comprises a mechanism enabling the pitch angle of the blades to be varied, so as to adapt the thrust produced by the propeller to different phases of flight.

[0004] The design of a propeller blade involves several disciplines which generally have conflicting objectives. The propeller blade must enable optimal aerodynamic performance (i.e. provide thrust while maximizing efficiency), guarantee the mechanical strength of the blade (i.e. withstand the mechanical constraints resulting from static and dynamic loads), while limiting the mass and acoustic signature. In particular, the improvement of the aerodynamic performance of the propeller tends to increase the By Pass Ratio (BPR), which translates into an increase in the outer diameter of the propeller, and thus in the span of the blades.

[0005] At the same time, in some turbine engine architectures, the engine is started with a very open pitch (known as feathering). Indeed, this start position enables the power to be consumed by the torque, which ensures the safety of the machine by guaranteeing low propeller speeds. More precisely, according to a simple consideration, the power is proportional to the product of the speed and the torque. However, the torque increases with the incidence, which can be increased by the pitch. Indeed, the skilled person in the field of aerodynamics understands that the force generated on a blade profile is approximately perpendicular to the chord in first approximation, and can be decomposed into two components: a thrust along the engine axis and a drag of the blade in the plane of the propeller. Thus, as the pitch of the blades increases, the force generated moves towards the plane of the propeller, increasing the drag of the aerodynamic profile and reducing the thrust.

[0006] Thus, with a propeller start in feather, the thrust generated by the propeller is zero, the torque is maximum and the speed is minimum. However, the incidence becomes so high that the blades are subjected to a turbulent, highly raised aerodynamic flow generating a strong vibratory excitation. This excitation is broadband due to the small eddies of the raised area, but it is also strong at certain specific frequencies due to strong Karman recirculations, which lead to significantly oscillating aerodynamic forces. In particular, on blades with a large chord and a large span, which generate a large drag, these forces are strong even if the speed is not high.

[0007] In the prior art, the usual practice is to attach the blade to the support of the blade with an attachment called brochée. The blade comprises a root having a generally dovetail shape and is intended to engage in a bag of the support in a form-fit manner, the bag being generally manufactured by broaching.

[0008] For blades with broached attachments, this aerodynamic force is so strong that it can cause a rigid solid motion of the blade root in its bag similar to a rotation. During the feather start, the reduced speed of the fan is not able to generate enough centrifugal force to prevent these movements caused by the aerodynamic force. Frictional damage of the blade and of the gaskets inserted between the root and the bottom of the bag results after only a few revolutions. Due to the fact that variable-pitch blades are usually equipped with feathering systems, this problem can also occur in the case of windmill training after an engine failure.

[0009] Moreover, due to the effect of the installation of the engine on the aircraft and the direction of the upstream non-limited flow, strong vibratory excitations can also occur on non-ducted architectures at much higher rotational speeds. Indeed, unducted engines are affected by the ground and the fuselage, which cause a distortion of the propeller movement and the flow rate depending on the engine azimuth angle. This leads to a vibratory response of the propeller blades on the first engine orders IN, 2N and 3N (possibly higher). On the other hand, in the absence of an air inlet sleeve, the direction of the air flowing through the blades is not parallel to the engine shaft. This slip angle generates forces called "IP" which lead to a vibratory response of the propeller blades on the engine order IN. Similarly, these forces IP can also be generated during the climb or approach phases of the aircraft when the air flows through the blades with an incidence angle. If the attachment of the blades is not suitable, these high rotational speed vibratory excitations can lead to the same frictional damage as described above.

[0010] For all these reasons, the broached attachment is currently not a viable solution for variable-pitch propeller blades with a large chord and a large span.

[0011] There is therefore a need for attachment technology of the variable-pitch propeller blade that makes it possible to limit the blade rotation during all the flight phases that can excite the vibration modes of the blade.

[0012] Furthermore, it is also known to enclose the root of the blade in a barrel, generally of metal, which matches the shape of the root. In particular, this barrel makes it possible to ensure the connection between the root of the blade and the inner ring of the guide bearing, so that the angular-pitch setting of the blade can be associated with the hub. This barrel is attached very carefully to the root of the blade so as to limit the rotation between the blade and the barrel as much as possible.

[0013] However, despite all the precautions, it is still often observed that the blade can oscillate due to some deflection in the barrel. There is therefore a need to ensure that the rotation of the blade is as much as possible limited with respect to the inner guide bearing ring. SUMMARY

[0014] The invention proposes an assembly for an aircraft turbomachine, comprising a propeller blade and a pitch-setting system for setting the pitch of the blade, the blade having a root extending from an upper end to a free lower end, the upper end being connected to the blade of the blade, the root having a convex development called "bulb", the pitch-setting system being intended to set the pitch of the blade about a pitch axis, the assembly comprising:

[0015] - a cup, the cup being radially delimited by an annular wall extending about the pitch axis, the cup comprising a lower bottom closed by a bottom wall and an upper opening, the bulb being intended to be axially inserted into the cup through the upper opening;

[0016] - an annular retaining ring extending about the bulb, the annular retaining ring being limited at least in axial displacement relative to the cup towards the upper opening, the annular retaining ring having an annular bearing surface which limits the passage cross section of the upper opening and which is intended to be in axial contact with the upper surface of the bulb so as to block the axial displacement of the root towards the upper opening.

[0017] The assembly according to the invention is characterized in that it comprises a lower seat carried by a different part than the annular retaining ring, the root being axially supported in the cup in the direction of the lower bottom by the lower seat, the lower seat and / or the annular retaining ring being mounted axially translationally mobile relative to the cup by at least one clamping mechanism so as to make it possible to axially clamp the bulb between the lower seat and the annular bearing surface of the annular retaining ring.

[0018] This ensures that the root is attached to the cup without play, thus preventing the rotation of the blade in the cup. This is in particular different from the embodiments of the prior art in which the root is enclosed in a barrel that is assembled.

[0019] According to another feature of the assembly manufactured according to the teachings of the application, the annular bearing surface of the annular retaining ring is in direct contact with the ball portion, and the lower seat portion is in direct contact with the root portion.

[0020] This ensures that the root portion cannot move with respect to the annular bearing surface and the lower seat portion, due to the absence of elements fitted to the root portion, in particular due to the absence of a cylindrical portion enclosing the root portion.

[0021] According to another feature of the assembly manufactured according to the teachings of the application, the annular bearing surface of the annular retaining ring has a shape complementary to the shape of the upper surface of the ball portion.

[0022] This ensures that the force is better distributed over a greater surface of the ball portion.

[0023] According to another feature of the assembly manufactured according to the teachings of the application, the upper surface of the ball portion has a substantially truncated cone shape.

[0024] This makes it possible to ensure that the ball portion is held axially and radially in the cup portion.

[0025] According to another feature of the assembly manufactured according to the teachings of the application, the annular retaining ring is made up of a plurality of parts.

[0026] According to another feature of the assembly manufactured according to the teachings of the application, the annular retaining ring is made up of at least three parts.

[0027] The fact that the annular retaining ring is made up of a plurality of parts makes it possible to simplify the installation of the root portion in the cup portion.

[0028] According to another feature of the assembly manufactured according to the teachings of the application, the bottom wall is configured to cooperate in a form-fitting manner with the free lower end of the root portion, so that the cup portion is rotationally fixed with the root portion about the pitch axis.

[0029] According to another feature of the assembly manufactured according to the teachings of the application, the pitch setting system further comprises:

[0030] - a lower rolling guide bearing, the lower rolling guide bearing extending about the pitch axis and being mounted about a lower portion of the annular wall,

[0031] - an upper rolling guide bearing, the upper rolling guide bearing extending about the pitch axis and being mounted about an upper portion of the annular wall.

[0032] According to another feature of the assembly manufactured according to the teachings of the application, at least one of the guide bearings has an inner ring of the guide bearing that is integrated into the cup portion.

[0033] According to another feature of the assembly made according to the teachings of the present application, the lower seat is axially translationally movably mounted in the cup by at least one clamping mechanism.

[0034] According to another feature of the assembly made according to the teachings of the present application, each clamping mechanism is formed by an axial screw received in a threaded portion complementary to the lower seat, the lower end of the screw axially bearing against a face of the cup turned toward the upper opening.

[0035] According to another feature of the assembly made according to the teachings of the present application, the clamping mechanism is formed by an annular clamping ring surrounding the lower seat and axially bearing against an annular face of the cup turned toward the upper opening, the annular clamping ring comprising an internal threaded portion cooperating with an annular external threaded portion axially fixed to the lower seat, one of the external threaded portion or the annular clamping ring being blocked against rotation relative to the cup.

[0036] According to another feature of the assembly made according to the teachings of the present application, the external threaded portion is integrally made with a seat ring carrying the lower seat.

[0037] According to another feature of the assembly made according to the teachings of the present application, the annular retaining ring is axially translationally movably mounted in the cup by at least one clamping mechanism.

[0038] According to another feature of the assembly made according to the teachings of the present application, the clamping mechanism comprises wedges distributed around the annular retaining ring and inserted between a frustoconical face of the annular wall of the cup turned toward the lower bottom and an outer peripheral stop face of the annular retaining ring.

[0039] According to another feature of the assembly made according to the teachings of the present application, the clamping mechanism comprises a clamping ring screwed into the cup and having a frustoconical annular face biasing the wedges to axially clamp the annular retaining ring against the bulb against the lower bottom of the cup.

[0040] According to another feature of the assembly made according to the teachings of the present application, the annular retaining ring is equipped, on its outer periphery, with external dog teeth cooperating with complementary internal dog teeth of the annular wall of the cup to block axial displacement of the annular retaining ring toward the upper opening.

[0041] According to another feature of the assembly made according to the teachings of the present application, the annular retaining ring is integrally made with the cup.

[0042] According to another feature of the assembly made according to the teachings of the present application, the lower seat is axially translationally movably mounted in the cup by at least one clamping mechanism.

[0043] According to another feature of the component manufactured in accordance with the teachings of the present invention, a gasket is provided to be axially inserted between the cup portion and the lower seat portion.

[0044] According to another feature of the component manufactured in accordance with the teachings of the present invention, the lower seat and the cup are integrally formed. Attached Figure Description

[0045] Other features and advantages of the invention will become apparent from the following detailed description, and with reference to the accompanying drawings, in order to understand it:

[0046] Figure 1 This is a schematic perspective view of a propeller blade for an aircraft turbine engine, and illustrates the present invention.

[0047] Figure 2 yes Figure 1 A magnified view of a portion, showing the root of the blade.

[0048] Figure 3 It is based on Figure 4 A cross-sectional view of the cross-sectional plane Pb, showing the shape and position of the free lower end of the root relative to the pitch axis.

[0049] Figure 4 It shows Figure 1 An axial cross-sectional view of the root of the blade, wherein the root of the blade is attached to the cup portion of the pitch setting system manufactured according to a first embodiment of the present invention.

[0050] Figure 5 It shows Figure 4 A perspective view of the cup section.

[0051] Figure 6 This illustrates a second embodiment of the invention, and... Figure 4 Similar views,

[0052] Figure 7 This illustrates the third embodiment of the present invention, and... Figure 4 Similar views,

[0053] Figure 8 This illustrates the fourth embodiment of the present invention, and... Figure 4 A similar view.

[0054] Figure 9 This is a perspective view showing the root of the blade, which is configured to insert into... Figure 8 The cup portion of the embodiment shown in the figure.

[0055] Figure 10 It is along Figure 8A cross-sectional view of plane 10-10, which shows the position of the blade root when inserted into the cup.

[0056] Figure 11 It shows the root of the annular retaining ring attached to the cup portion via a dog-tooth clutch, and... Figure 10 A similar view.

[0057] Figure 12 This illustrates the fifth embodiment of the present invention, and... Figure 4 A similar view.

[0058] Figure 13 This illustrates the sixth embodiment of the present invention, and... Figure 4 A similar view. Detailed Implementation

[0059] In the following description, elements with the same structure or similar function will be represented by the same reference numerals.

[0060] In the remainder of the specification, an axial direction along the pitch axis "A" of the blade is used, extending upwards from the bottom (near the root of the blade) towards the free lower end of the blade. A radial direction is also used, extending outwards from the inside near the pitch axis and orthogonally to the pitch axis.

[0061] Figure 1 The blade 10 of a propeller for an aircraft turbine engine is shown; the propeller may be ducted or unducted.

[0062] The whorl 10 includes blades 12 connected to the root 14.

[0063] The blade 12 has an aerodynamic profile and includes a ventral arch 12a and a stern arch 12b, which are connected by an upstream leading edge 12c and a downstream trailing edge 12d, the terms upstream and downstream referring to the flow of gas around the blade 12 during operation.

[0064] The blade 12 has a free upper end, referred to as the top, and a lower end connected to the root 14.

[0065] In the example shown, the blade 10 is made of composite material by an injection molding method known as Resin Transfer Molding (RTM). This method involves preparing a fiber preform 18 by three-dimensional weaving, then arranging the preform in a mold and injecting a polymerizable resin, such as epoxy, to impregnate the preform. After the blade 12 has cured and hardened, the upstream leading edge 12c of the blade is typically reinforced by a metal sheath 20, which is assembled and attached, for example, by gluing.

[0066] The blade 10 comprises a spar 22. The spar 22 comprises a portion which forms the core of the blade 12. The portion of the spar 22 which forms the core of the blade 12 is intended to be inserted into the preform 18 prior to resin injection. The spar 22 also comprises a portion which extends on opposite sides of the top of the blade 12 to form the root 14.

[0067] Preferably, the spar 22 is made of composite material. For example, the spar is a 3D woven carbon fiber reinforced epoxy organic matrix composite in which, at the height of the aerodynamic channel, the warp direction is mainly radial and the weft is mainly oriented according to the chord of the blade 12.

[0068] Alternatively, the spar can also be formed by a mechanically more advantageous assembly consisting of different organic matrix composites (thermoset, thermoplastic or elastomer) reinforced with long fibers (carbon, glass, aramid, polypropylene) arranged in various fabrics (woven, braided, knitted, unidirectional).

[0069] Although not shown, the blade 12 can be hollow or solid and comprise an internal cavity filled with a foam or honeycomb type filler. This filler is mounted around the spar 22 and is covered with a skin consisting of an organic matrix composite to increase the impact resistance of the blade 12.

[0070] The metal sheath 20 can be titanium or a titanium alloy, stainless steel, steel, aluminum, nickel, etc. The concave face 12a or even the convex face 12b of the blade 12 can be covered with a polyurethane film to prevent erosion.

[0071] The root 14 does not here enclose a metal annular cylinder which encloses the root.

[0072] The axis "A" is the elongation axis of the blade 10 and of the blade 12, in particular the pitch axis "A" of the blade 10, i.e. the axis around which the angular position of the blade 10 is adjusted. This axis is also generally the radial axis, so that it extends along a radius with respect to the rotation axis of the propeller equipped with this blade 10.

[0073] The root 14 has a particular shape which is best visible in Figure 2 The root 14 generally comprises three portions:

[0074] - a free lower end 28, the free lower end being positioned opposite the blade 12,

[0075] - an upper column 30, the upper column being located on one side of the blade 12, and

[0076] - a convex development called "bulb" 32, the convex development being located between the free lower end 28 and the upper column 30.

[0077] In the example shown, the free lower end 28 has a substantially parallelepiped shape. As can be seen in Figure 3 the free lower end 28 is offset from the pitch axis “A” to achieve a correct detrompage or indexation, as will be explained in more detail below.

[0078] With reference to Figure 4 , Pb is defined as a transverse plane, i.e. a plane perpendicular to the pitch axis “A”, which substantially passes through a middle of the free lower end 28 measured along the pitch axis “A”. This plane Pb is referred to as a bottom plane or lower plane. Figure 3 The cross-sectional shape of the free lower end 28 in this plane Pb is shown. This cross-section, referred to as a lower cross-section, has a value or surface area, e.g. a maximum value or surface area, denoted Sb and is generally rectangular in shape in the example shown.

[0079] As will be described below, the free lower end 28 is configured to cooperate with a pitch setting system 34 of the blade 10.

[0080] With reference again to Figure 2 , the upper column 30 has a relatively complex shape which enables to provide a transition between the root 14 and the spar portion 22, the spar portion forming a core of the blade 12. The upper column 30 schematically comprises:

[0081] - two flanks 30a, 30b, respectively on one side of the concave 12a and on one side of the convex 12b of the blade 12, which converge towards each other along the pitch axis “A” and towards the top of the blade 12, and

[0082] - two edges, respectively an upstream edge 30c and a downstream edge 30d, which, inversely, diverge from each other along the pitch axis “A” and towards the top of the blade 12.

[0083] With reference to Figure 4 , Ph is defined as a transverse plane passing through the upper column 30, in particular through a lower end of the upper column 30. This plane Ph is referred to as a high plane or upper plane. In this plane, the upper column 30 can have a non-circular cross-sectional shape, e.g. an elliptical, oblong, square or rectangular shape. This cross-section, referred to as a high cross-section, has a value or surface area, e.g. a maximum value or surface area, denoted Sh.

[0084] The bulb 32 has a substantially convex shape or dome shape, the convexity or dome extending around the pitch axis “A”.

[0085] Pm is defined as a median plane passing through the bulb 32, in particular at the portion of the bulb having the largest cross section (hereinafter referred to as median cross section, denoted Sm). This plane Pm is referred to as median plane. In this plane, although not limitative, the bulb 32 can have a circular shaped cross section.

[0086] It is understood that the plane Pm is located between the plane Pb and the plane Ph. The largest cross section dimension of the bulb 32 decreases from the plane Pm (Sm) to the plane Ph, and decreases from the plane Pm towards the plane Pb. It is thus understood that Sm is greater than Sb and Sh. Moreover, in the example described, Sh is greater than Sb.

[0087] The blade 10 is intended to be mounted in a pitch setting system 34 enabling the angular position of the blade to be varied relative to the hub 36 of the propeller about a pitch axis "A".

[0088] To this end, the pitch setting system 34 comprises bearings 54, 56. Here, the number of bearings 54, 56 is two, respectively a lower bearing 54 and an upper bearing 56.

[0089] The bearings 54, 56 are of the ball rolling type. In the example shown, the bearings have different diameters, and the balls of the bearings also have different diameters.

[0090] The lower bearing 54 extends substantially between the plane Pm and the plane Pb, and thus around a lower portion of the bulb 32. The diameter of this lower bearing 54 is smaller than the diameter of the upper bearing 56, and the diameter of the balls of the lower bearing is greater than the diameter of the balls of the upper bearing 56.

[0091] The lower bearing 54 is also of the angular contact type. In the example shown, the bearing points or bearing surfaces of the balls on the raceways of the rings 54a, 54b of the balls are located on a frustoconical surface S1 extending along the pitch axis "A", and the largest diameter of which is located on the side of the tip of the blade 10.

[0092] The upper bearing 56 extends substantially between the plane Pm and the plane Ph, and thus around an upper portion of the bulb 32. The upper bearing 56 is also of the angular contact type. In the example shown, the bearing points or bearing surfaces of the balls on the raceways of the rings 56a, 56b of the balls are located on a frustoconical surface S2 extending along the pitch axis "A", and the largest diameter of which is located on the side of the free lower end 28 of the root 14 of the blade 10.

[0093] Figure 4 and Figure 5 An example embodiment of the pitch setting system 34 is shown.

[0094] The pitch setting system 34 comprises a cup 58. The cup 58 comprises an annular wall 58a extending around the pitch axis "A". The annular wall 58a radially delimits an inner volume of the cup 58. The inner volume of the cup 58 is closed downwardly by a bottom wall 58b extending opposite the free lower end 28 of the root 14. The cup 58 has an upper opening 58c at an upper axial end of the cup, the upper opening being radially delimited by an upper end edge of the annular wall 58a. The free lower end 28 of the root 14 and the bulb 32 are intended to be axially inserted inside the cup 58 through the upper opening 58c.

[0095] The annular wall 58a and the bottom wall 58b are integrally manufactured.

[0096] The bottom wall 58b is configured to cooperate in a form-fit manner with the free lower end 28 of the root 14, so that the cup 58 is rotationally fixed to the root 14 around the pitch axis "A" and thus constitutes a pivot for the associated blade 10.

[0097] In this case, it will be understood that the bottom wall 58b comprises a recess 60 having a non-circular, in particular rectangular, cross-section and configured to receive the free lower end 28, as illustrated in Figure 3 and Figure 4 . As can be seen in Figure 2 , this recess 60 is eccentric with respect to the pitch axis "A" in a similar manner to the free lower end 28. This eccentricity makes it possible to carry out indexing and correct fixing when inserting and mounting the root 14 in the cup 58 and to have only one engagement position for the free lower end 28 in the recess 60.

[0098] The recess 60 is located on an upper or inner surface of the bottom wall 58b of the cup 58, thus inside the cup 58 and oriented on the side of the root 14.

[0099] The pitch setting system 34 generates a torque at the root 14 of the blade 10 which counteracts the torsional moment generated by the aerodynamic forces and the centrifugal forces. Advantageously, the free lower end 28 is directly inserted into the recess 60 without the need to insert fitting elements to directly force the root 14 to rotate. This provides a more direct force path, with the torsional moment being directly applied to the root 14. The size of the lower cross-section is strictly less than the maximum size of the intermediate cross-section, to limit the total circumferential size to this height.

[0100] Since the portion of the bearing surface that is located in height between the median section and the high section is located inside the cup 58, contrary to the prior art with a drilled attachment in the pivot, the position of the median stretch between the two bearings 54, 56, which is the section of the ball 32 where the radial volume is the largest, is very advantageous in terms of radial overall size. This contributes to reducing the radial overall size of the pitch setting system 34.

[0101] This makes it possible to reduce the diameter of the lower bearing 54 located below the median section. Thus, the root 14 of the blade 10 can be integrated lower along the pitch axis "A", which greatly reduces the theoretical hub ratio associated with the integration of the root 14. It is known to the person skilled in the art that a low hub ratio improves the performance of the engine, in particular since an engine with a low hub ratio is more compact and thus lighter. This last point is a very important advantage of the technical solution compared to the competition, where the competition generally has a barrel with a cylindrical external shape.

[0102] The bottom wall 58b comprises a lower or external surface located on the opposite side of the root 14 and comprises a cylindrical extension 62 extending along the pitch axis "A" and comprising an external threaded part or an external straight spline 64 for the rotational coupling of the pitch setting system 34 with a pitch change mechanism not shown, which is common to the different pitch setting systems 34 and blades 10 of the propeller.

[0103] It can be seen in Figure 4 that the cup 58 is designed to support the bearings 54, 56 which ensure the centring and guiding of the cup 58 around the pitch axis "A" with respect to the hub 36 of the turbine engine.

[0104] The bearings 54, 56 can form part of the pitch setting system 34. In particular, at least one of the guide bearings can have an inner ring of the guide bearing which is integrated into the cup 58.

[0105] This is the case for the lower bearing 54, the inner ring 54a of which is integrated into the cup 58. In practice, this means that the cup 58 comprises a raceway 54aa on the outer periphery of the cup on which the balls of the lower bearing 54 roll directly. This raceway comprises an annular surface with a concave curved section. This raceway is located at the annular wall 58a and at the lower end of the cup 58. The outer ring 54b of the lower bearing 54 is attached to the hub 36, for example by shrink fitting. Furthermore, advantageously, the cup 58 is designed to exert a pre-load on the lower bearing 54.

[0106] The outer ring 56b of the upper bearing 56 is attached to the hub 36, for example by shrink fitting. The inner ring 56a of the upper bearing engages on and around the free upper end of the cup 58 and the annular wall 58a. This end of the annular wall 58a comprises an outer cylindrical surface 76 for mounting the inner ring 56a and an outer threaded portion for screwing on a nut 78 intended to be axially supported on the inner ring 56a to keep the inner ring axially clamped against an outer cylindrical shoulder 80 of the cup 58.

[0107] According to the teachings of the present application, in order to axially retain the root 14 within the cup 58, in particular against centrifugal forces, an annular retaining ring 82 is provided which extends around the bulb 32 within the cup 58. The annular retaining ring 82 is connected to the cup 58 to be limited at least in axial displacement relative to the cup 58 towards the upper opening 58c.

[0108] The annular retaining ring 82 has an annular bearing surface 84 which is oriented towards the lower bottom of the cup 58. The annular bearing surface 84 is intended to limit the passage cross section of the upper opening 58c of the cup 58 to prevent the root 14 from being removed through the upper opening 58c by blocking of the bulb 32. More particularly, the annular bearing surface 84 is intended to be in axial contact with an upper surface 86 of the bulb 32 to block axial displacement of the bulb 32 towards the upper opening 58c.

[0109] It is also important to firmly attach the root 14 in the cup 58 to prevent any rotation of the blade 10 relative to the cup 58 during use of the blade. To this end, the pitch setting system 34 comprises a lower seat 88 formed by a face turned towards the upper opening 58c of the cup 58 through which the root 14 is axially supported in the cup 58 in the direction of the lower bottom.

[0110] The lower seat 88 is a separate part from the annular retaining ring 82. At least one of the lower seat 88 and / or the annular retaining ring 82 is axially translationally movably mounted relative to the cup 58 by at least one clamping mechanism 90 to enable the bulb 32, which is made of composite material here, to be axially clamped between the lower seat 88 and the annular bearing surface 84 of the annular retaining ring 82. This makes it possible to prevent an axial gap between the annular bearing surface 84 and the blade 10.

[0111] In order for such an axial gap not to occur, the bulb 32 is clamped between the lower seat 88 and the annular bearing surface 84 of the annular retaining ring 82 with a sufficiently high prestress which exceeds the maximum axial force that can be exerted on the blade 10 during operation of the propeller, for example of the order of tens of thousands of Newton.

[0112] The annular retaining ring 82 is made of a metallic material such as steel, titanium or a titanium alloy (e.g. TA6V).

[0113] The lower seat 88 is made of a metallic material such as steel, titanium or a titanium alloy (e.g. TA6V).

[0114] To ensure that the blade 10 is axially retained in the cup 58 without play, the annular bearing surface 84 of the annular retaining ring 82 is in direct contact with the ball 32 without the need for an interposed insert. In particular, the annular bearing surface 84 of the annular retaining ring 82 has a shape complementary to the upper surface 86 of the ball 32 to distribute the forces over a large area of the ball 32.

[0115] To simultaneously enable the root 14 to be radially retained in the cup 58, the upper surface 86 of the ball 32 has a substantially frustoconical shape and the annular bearing surface 84 has a complementary shape. The annular bearing surface 84 extends substantially from the median plane to the upper opening 58c of the cup 58, for example. Thus, under the effect of centrifugal force, the root 14 is centred radially in the annular bearing surface 84. This shape thus enables a stable position of the blade 10 relative to the pitch axis "A" to be provided during rotation of the propeller.

[0116] The surface area of the annular bearing surface 84 is maximised by utilising the entire circumference of the bottom of the blade 10 compared with a drilled attachment. In a drilled attachment, only two different surfaces of the root 14 of the blade 10, respectively on the intrados and the extrados, are supported on the bearing surface, whereas the surfaces of the root 14 of the blade 10 on the leading edge and the trailing edge are free. Furthermore, the height of the bearing surface in the direction of the pitch axis "A" is much greater compared with a drilled attachment, which also contributes to significantly increasing the surface area of the bearing surface. This large support surface enables the contact pressure to be reduced under all operating conditions.

[0117] The inner diameter of the annular retaining ring 82, measured at the upper end of the annular bearing surface 84, is substantially less than the diameter of the median section of the ball 32. To enable the annular retaining ring to be arranged around the ball 32 in a simple manner, the annular retaining ring 82 is made of several parts in this case, two of the parts 82a, 82b being shown in Figure 4 These parts 82a, 82b are distributed uniformly around the pitch axis "A".

[0118] These parts 82a, 82b can be in contact with each other circumferentially, so that the annular bearing surface 84 has a continuous annular shape.

[0119] In a variant which will be detailed hereinafter, the parts 82a, 82b are spaced apart from each other circumferentially, so that the annular bearing surface 84 has an annular shape which is discontinuous between the two parts 82a, 82b.

[0120] The root 14 is supported on the lower seat 88 by the lower face 92 of the bulb 32. The lower seat 88 thus takes the form of an annular support surface extending around the pitch axis "A". In particular, the lower seat 88 coincides with the opposite lower face 92 of the bulb 32 so as to in particular enable the contact pressure between the lower seat 88 and the bulb 32 to be reduced. The lower seat 88 is in direct contact with the root 14, which is made here of composite material.

[0121] In order to enable the bottom of the root 14 to be centred in the cup 58, the lower face 92 of the bulb 32, which is in contact with the lower seat 88, has here a substantially frustoconical shape which is convex, and the lower seat 88 has a complementary shape. The root 14 is thus not only axially supported towards the lower bottom of the cup 58, but is also held in place radially in the cup 58.

[0122] In a variant of the application not shown, the lower seat is supported against the lower face of the free lower end of the root.

[0123] According to a first embodiment of the application shown in Figure 4 The lower seat 88 is carried in the cup 58 by at least one insert. The lower seat 88 is thus interposed between the root 14 and the cup 58. The lower seat 88 is mounted in translational movement by at least one clamping mechanism 90.

[0124] The lower seat 88 is here formed by the upper face of a seat ring 94 which is manufactured in one piece. The lower seat 88 is intended to be supported against the lower annular face of the bulb 32. In this respect, the lower seat 88 has a continuous annular shape centred on the pitch axis "A".

[0125] The seat ring 94 carrying the lower seat 88 is mounted axially supported towards the lower bottom of the cup 58 by an annular clamping ring 96 belonging to the clamping mechanism 90. The annular clamping ring 96 surrounds the lower seat 88.

[0126] The annular clamping ring 96 has an outer peripheral rim 98 which is supported against an annular shoulder face 100 of the cup 58. The shoulder face 100 extends radially inwards from the annular wall 58a and turns towards the upper opening 58c. This shoulder face is located slightly above the median plane Pm.

[0127] The annular clamping ring 96 is intended to cooperate with the seat ring 94 to axially clamp the lower seat 88 upwards against the bulb 32 by being supported on the shoulder face 100. To this end, the annular clamping ring 96 is fixed axially without displacement to an internal thread which is screwed onto a complementary external thread produced on the outer face of the seat ring 94.

[0128] To enable clamping of the lower seat 88 against the ball portion 32 by turning the annular clamping ring 96, one of the external thread portions or the external thread portions is blocked to prevent rotation of the external thread portion relative to the cup portion 58.

[0129] This relates to the internal thread portion as a non-limiting example. In this regard, the annular clamping ring 96 is particularly fixed against rotation relative to the cup portion 58 by a complementary shape (e.g. by a plate or pin) interposed between the annular clamping ring 96 and the cup portion 58.

[0130] In the example shown in Figure 4 , the external thread portion is manufactured integrally with the lower seat 88.

[0131] In a variant not shown, the external thread portion is formed by a ring fitted to the seat ring and axially fixed to the lower seat. Said ring is for example rotatably mounted around the seat ring.

[0132] Furthermore, the annular retaining ring 82 is fitted to the cup portion 58. The annular retaining ring is made of a plurality of distinct portions 82a, 82b intended to be axially connected to the cup portion 58 by a dog clutch device. To facilitate the insertion of the portions 82a, 82b, the annular retaining ring 82 is made of at least three portions, in Figure 4 only two of the three portions are shown in

[0133] Thus, each portion 82a, 82b comprises at least one external dog portion 102 configured to cooperate with a complementary internal dog portion 104 of the annular wall 58a of the cup portion 58. For example, the external dog portions 102 each have an angular extension around the pitch axis "A" of between about 20° and 30°.

[0134] The internal dog portions 104 of the cup portion 58 are best observed in Figure 5 . These internal dog portions 104 are uniformly spaced around the pitch axis "A". There are six internal dog portions in the non-limiting example shown. For example, the internal dog portions each have an angular extension around the pitch axis "A" of between about 20° and 30°.

[0135] The external dog portions 102 are complementary to the internal dog portions 104 and are configured to cooperate with these internal dog portions 104 by a dog clutch. The dog clutch is a mounting method well known in the aeronautical field, which will be described in more detail later.

[0136] When installing the assembly formed by the vane 10 and the pitch setting system 34, the seat ring 94 carrying the lower seat 88 is first inserted into the cup 58 through the upper opening 58c of the cup. The seat ring 94 is pre- threaded with the annular clamping ring 96 of the seat ring such that, when the annular clamping ring 96 is pressed against the shoulder face 100, the lower seat 88 occupies its lowest position in the cup 58. The seat ring 94 and the annular clamping ring 96 of the seat ring are positioned such that the outer periphery 98 of the annular clamping ring 96 is supported on the shoulder face 100 of the cup 58.

[0137] Then, the root 14 is inserted with its free lower end 28 through the upper opening 58c of the cup 58. The root 14 is positioned such that the bulb 32 is received against the lower seat 88.

[0138] Then, the portions 82a, 82b of the annular retaining ring 82 are inserted into the cup 58 through the upper opening 58c of the cup. This insertion is facilitated since the lower seat 88 is in its lowest position. This provides sufficient space to insert the outer canine 102 between the inner canines 104 without being obstructed by the bulb 32.

[0139] The outer canines 102 of the portions 82a, 82b are arranged in axial coincidence with the angular spaces between the inner canines 104. Then, the outer canines 102 of each portion 82a, 82b are inserted axially downwards into these spaces to be located below the inner canines 104. Finally, the portions 82a, 82b are rotated around the pitch axis "A" until the outer canines 102 are axially aligned with the inner canines 104. Thus, the portions 82a, 82b of the annular retaining ring 82 are limited in axial displacement towards the upper opening 58c by the portions' outer canines 102 contacting the inner canines 104 of the cup 58.

[0140] Subsequently, the clamping mechanism 90 is operated to enable the lower seat 88 to clamp axially against the bulb 32. This has the effect of raising the root 14 relative to the cup 58 towards the upper opening 58c of the cup until the bulb 32 is axially supported against the annular bearing surface 84 of the annular retaining ring 82. Thus, the clamping force is transmitted from the lower seat 88 to the bulb 32, then from the bulb 32 to the annular retaining ring 82, and from the annular retaining ring 82 to the cup 58 via the canines 102, 104. A counter force is formed between the annular clamping ring 96 and the cup 58 via the shoulder face 100. Thus, the root 14 is in direct contact only with the annular bearing surface 84 of the annular retaining ring 82 and with the lower seat 88 of the seat ring 94.

[0141] To actuate the clamping mechanism 90, a spacing is angularly retained between at least two portions 82a, 82b of the annular retaining ring 82, so as to enable a clamping tool (not shown) to be inserted through the upper opening 58c. Here, the clamping is performed by a tool comprising at least one sprocket, which is inserted into the cup 58. The sprocket is intended to mesh with an external toothing 106 carried by the outer periphery of the lower seat 88. The external toothing 106 is here arranged directly above an annular clamping ring 96.

[0142] A second embodiment of the application is shown in Figure 6 . This second embodiment comprises many similarities with the first embodiment. Compared to the first embodiment, only the clamping mechanism 90 for clamping the lower seat 88 is changed. In the following, only the elements different from the embodiment shown in Figure 4 will be described.

[0143] In this variant embodiment, the lower seat 88 is also carried by a seat ring 94. However, the seat ring 94 is here mounted on the cup 58 by a plurality of clamping mechanisms 90, which are evenly distributed around the pitch axis "A".

[0144] Here, each clamping mechanism 90 comprises a screw 108, which is rotatably mounted in a support 110, which is supported downwards in the cup 58. The support is thus intended to be in close contact with the cup 58. The screw 108 is axially fixedly mounted in the support. The axial shank of the screw 108 is screwed into a complementary threaded portion 113 of the lower seat 88, which opens axially downwards. The lower end of the screw 108 is axially supported by the support 110 against a face of the cup 58, which turns towards the upper opening 58c, in this case the bottom wall 58b.

[0145] In particular, the screw 108 is mounted in axial alignment with the ball 32. In order to enable the screw 108 to turn in either direction, the upper end of the screw 108 is provided with a notch 112, which can cooperate with a screwdriver having a complementary notch. In order to enable the screwdriver to be inserted, the ball 32 is provided with an axial aperture 114, which is arranged in register with the threaded portion 113 of the lower seat 88, which opens axially upwards into the lower seat 88. Furthermore, the clamping mechanism 90 is arranged angularly between the two portions 82a, 82b of the annular retaining ring 82, so as to enable the screwdriver to easily access the axial aperture 114.

[0146] The rotation of the screw 108 thus enables the lower seat 88, and thus the ball 32, to be lifted from the cup 58 and clamped against the annular bearing surface 84 of the annular retaining ring 82.

[0147] A third embodiment of the application is shown in Figure 7The third embodiment comprises many similarities with the second embodiment. Compared to the second embodiment, only the position of the clamping mechanism 90 of the lower seat 88 has been changed. In the following, only the elements that differ from the embodiment shown in Figure 6

[0148] In this embodiment, the screw 108 of the clamping mechanism 90 is arranged to cooperate with a threaded portion 113 formed in the outer peripheral edge 116 of the lower seat 88. The screw 108 is thus supported on the shoulder face 100 of the cup 58. The shoulder face 110 is here located slightly above the median plane Pm. The screw 108 is thus not arranged in axial alignment with the ball 32. This arrangement makes it possible to avoid the need to manufacture an aperture in the ball 32 to pass a tool through. To enable a screwdriver to pass through, the screw 108 is advantageously arranged in alignment with the angular spacing that is preserved between the two portions 82a, 82b of the annular retaining ring 82.

[0149] A fourth embodiment of the application is shown in Figures 8 to 11 This embodiment is similar to the third embodiment in that the lower seat 88 and the clamping mechanism 90 of the lower seat are implemented and arranged similarly. In the following, only the differences between this fourth embodiment and the third embodiment will be described.

[0150] As shown in Figure 8 In this fourth embodiment, the annular retaining ring 82 is made in one piece with the cup 58, as shown in

[0151] To enable the root 14 to be inserted into the cup 58 and positioned relative to the annular retaining ring 82, it is desirable for the annular retaining ring 82 and the root 14 to be shaped so that the annular retaining ring and the root can cooperate in the manner of a dog clutch.

[0152] The ball 32 thus has a cross profile in cross section that is cruciform rather than convex as in the other embodiments, as shown in Figures 9 to 11 Figure 10 The annular retaining ring 82 is divided into four portions 82a, 82b, 82c, 82d that are angularly separated by spacing portions, as shown in

[0153] ​​After insertion of the root 14 between the portions 82a, 82b, 82c, 82d of the annular retaining ring 82, the root 14 is angularly rotated relative to the cup 58 about the pitch axis "A", in this case in the counterclockwise direction, to enable the branches 32a, 32b, 32c, 32d to be displaced into axial alignment with the portions 82a, 82b, 82c, 82d. The ball 32 is thus brought into contact with the annular bearing surface 84, preventing axial removal of the ball.

[0154] In this embodiment, the root 14 has no free lower end to enable the root to pivot relative to the cup 58. The lower seat 88 ensures a rotational connection between the cup 58 and the root 14. After clamping, the root 14 is in fact rotationally coupled to the lower seat 88 by friction. Furthermore, the seat ring 94 is equipped with a central protrusion 118 which is embedded in the recess 60 of the lower bottom of the cup 58 to ensure a rotational connection between the lower seat 88 and the cup 58.

[0155] Advantageously, as illustrated in Figure 11 , the screw 108 of the clamping mechanism 90 for clamping the lower seat 88 is angularly arranged between two branches of the ball 32 and thus between two portions 82a, 82b, 82c, 82d of the annular retaining ring 82, to enable a screwdriver to be inserted which will enable the lower seat 88 to be clamped against the ball 32.

[0156] A fifth embodiment of the invention is illustrated in Figure 12 . Contrary to the first four embodiments, here the annular retaining ring 82 is mounted to be axially translationally movable relative to the cup 58 by the clamping mechanism 90, while the lower seat 88 is here stationary relative to the cup 58.

[0157] As in the first embodiment, the annular retaining ring 82 is made of a plurality of distinct portions of the cup 58, here two portions 82a, 82b are illustrated. However, the portions 82a, 82b are not mounted into the cup 58 by dog clutch. To this end, the cup 58 comprises an inner shoulder 104' which extends continuously around the cup 58, and each portion 82a, 82b of the annular retaining ring 82 comprises a continuous outer rim 102' which is intended to be received under said inner shoulder 104'.

[0158] Contrary to the first embodiment, the lower seat 88 is here carried by a seat ring 94 which is axially fixedly mounted in the cup 58. More particularly, the seat ring 94 is received and axially supported on an annular shoulder face 100 of the ring wall 58a which turns towards the upper opening 58c. To enable the height of the lower seat 88 to be adjusted, shims 120 can be arranged between the shoulder face 100 and the seat ring 94.

[0159] When the root 14 is received and supported on the lower seat 88 of the root, the outer rim 102' of each portion 82a, 82b of the annular retaining ring 82 is received under the lower inner shoulder 104' of the cup 58, wherein each portion of the annular retaining ring is vertically movable between a lower position in which the annular support surface 84 is supported on the bulb 32 and an upper position in which the outer rim 102' is supported against the inner shoulder 104' of the cup 58.

[0160] In order to enable the portions 82a, 82b of the annular retaining ring 82 to be clamped at their lower position, the clamping mechanism 90 comprises a frustoconical support face 122 connected to the cup 58, which is here arranged under the inner shoulder 104' of the cup 58. The frustoconical support face 122 is turned towards the bottom wall 58b and towards the inside. It converges in the direction of the upper opening 58c of the cup 58. For example, it is formed by the lower surface of a ring attached under the inner shoulder 104'.

[0161] Optionally, not shown, the frustoconical support face 122 is formed directly by the lower surface of the inner shoulder 104'.

[0162] The clamping mechanism 90 also comprises wedges 124 distributed around the annular retaining ring 82. Each wedge 124 is inserted between the frustoconical support face 122 and the radially outer peripheral stop face 126 of the annular retaining ring 82, which is here formed by the upper surface of the outer rim 102'. Each wedge 124 can be formed by a seat ring section having a prismatic section, a sphere or any other component enabling the wedge to be supported in sliding manner both on the frustoconical support face and on the peripheral abutment face of the annular retaining ring 82 section.

[0163] The clamping mechanism 90 also comprises a clamping ring 128 screwed into the cup 58. The clamping ring 128 surrounds the bulb 32. It has an outer threaded portion cooperating by screwing with a complementary inner threaded portion carried here by the inner end face of the inner shoulder 104'. The clamping ring 128 has a biased frustoconical annular face 130 turned outwards and downwards. The biased frustoconical annular face 130 of the clamping ring 128 is arranged radially opposite the frustoconical support face 122 of the cup 58. When the clamping ring 128 is screwed into the cup 58, its biased face biases each wedge 124 radially outwards towards the frustoconical support face 122. In turn, the wedges 124 are axially pushed towards the lower bottom of the cup 58 to axially clamp the annular retaining ring 82 against the bulb 32. The bulb 32 is thus clamped against the lower seat 88 itself.

[0164] In this embodiment, since the clamping ring is arranged in the immediate vicinity of the upper opening 58c of the cup 58, and no component is present that could reduce the accessibility of the clamping ring, it is advantageously very easy to access the clamping ring 128.

[0165] According to an alternative embodiment of this fifth embodiment shown in Figure 13 the lower seat 88 is not carried by the insert, but is made integrally with the cup 58 (here the annular wall 58a).

[0166] Of course, these different embodiments can be combined, for example to obtain a pitch setting system 34 comprising a lower seat 88 and an annular retaining ring 82, both of which are axially translatable by means of the associated clamping mechanism.

Claims

1. An assembly for a turbine engine of an aircraft, the assembly comprising a propeller blade (10) and a pitch setting system (34) for setting the pitch of the propeller blade (10), the propeller blade (10) having a root (14) extending from an upper end connected to a blade (12) of the propeller blade (10) to a free lower end (28), the root (14) having a convex extension called "bulb (32)", the pitch setting system (34) being for setting the pitch of the propeller blade (10) about a pitch axis (A), characterized in that, The assembly comprises: - a cup (58) radially delimited by an annular wall (58a) extending around the pitch axis (A), the cup (58) comprising a lower bottom closed by a bottom wall (58b) and an upper opening (58c), the bulb (32) being intended to be axially inserted into the cup (58) through the upper opening, - an annular retaining ring (82) extending around the bulb (32), the annular retaining ring (82) being at least limited in axial displacement relative to the cup (58) towards the upper opening (58c), the annular retaining ring (82) having an annular bearing surface (84) which limits the passage cross section of the upper opening (58c) and which is intended to be in axial contact with an upper surface (86) of the bulb (32) to block the axial displacement of the root (14) towards the upper opening (58c), - a lower seat (88) carried by a separate part from the annular retaining ring (82), the root (14) being axially supported in the cup (58) in the direction of the lower bottom by the lower seat, the lower seat (88) and / or the annular retaining ring (82) being mounted axially translationally mobile relative to the cup (58) by at least one clamping mechanism (90) to enable the bulb (32) to be axially clamped between the lower seat (88) and the annular bearing surface (84) of the annular retaining ring (82).

2. The assembly of claim 1, wherein, The annular bearing surface (84) of the annular retaining ring (82) is in direct contact with the bulb (32) and the lower seat (88) is in direct contact with the root (14).

3. The assembly of claim 1 or 2, wherein, The annular bearing surface (84) of the annular retaining ring (82) has a shape complementary to that of the upper surface (86) of the bulb (32) and / or the upper surface (86) of the bulb has a substantially frustoconical shape.

4. The assembly of claim 3, wherein, The annular retaining ring (82) is made of a plurality of portions (82a, 82b, 82c, 82d).

5. The assembly of claim 1 or 2, wherein, The bottom wall (58b) is configured to cooperate in a form-fitting manner with the free lower end (28) of the root so that the cup (58) can be rotationally fixed with the root (14) around the pitch axis (A).

6. The assembly of claim 1 or 2, wherein, The pitch setting system also comprises: - a lower rolling guide bearing (54) extending around the pitch axis (A) and mounted around a lower portion of the annular wall (58a), - an upper rolling guide bearing (56) extending around the pitch axis (A) and mounted around an upper portion of the annular wall (58a).

7. The assembly of claim 1 or 2, wherein, The lower seat (88) is axially translationally mobile mounted in the cup (58) by at least one clamping mechanism (90).

8. The assembly of claim 7, wherein, Each clamping mechanism (90) is formed by an axial screw (108) received in a threaded portion (113) complementary to the lower seat (88), the lower end of the axial screw (108) being axially supported against a face of the cup (58) turned towards the upper opening (58c).

9. The assembly of claim 7, wherein, The clamping mechanism (90) is formed by an annular clamping ring (96) surrounding the lower seat (88) and axially supported against an annular face (100) of the cup (58) turned towards the upper opening (58c), the annular clamping ring (96) comprising an internal threaded portion cooperating with an annular external threaded portion axially fixed to the lower seat (88), one of the annular external threaded portion or the annular clamping ring (96) being blocked against rotation relative to the cup (58).

10. The assembly of claim 9, wherein, The annular external threaded portion is made integrally with a seat ring (94) carrying the lower seat (88).

11. The assembly of claim 1 or 2, wherein, The annular retaining ring (82) is axially translationally mounted in the cup (58) by at least one clamping mechanism (90).

12. The assembly of claim 11, wherein, The clamping mechanism (90) comprises wedges (124) distributed around the annular retaining ring (82) and inserted between a frustoconical face (122) of an annular wall (58a) of the cup (58) turned towards the lower bottom and an outer peripheral stop face (126) of the annular retaining ring (82).

13. The assembly of claim 12, wherein, The clamping mechanism (90) comprises a clamping ring (128) screwed into the cup (58) and having a frustoconical annular face (130) biasing the wedges (124) to axially clamp the annular retaining ring (82) against the ball (32) towards the lower bottom of the cup (58).

14. The assembly of any one of claims 8-10, wherein, The annular retaining ring (82) is equipped on its outer periphery with an outer dog tooth portion (102) complementary and cooperating with an inner dog tooth portion (104) of an annular wall (58a) of the cup (58) to block axial displacement of the annular retaining ring (82) towards the upper opening (58c).

15. The assembly of any one of claims 8-10, wherein, The annular retaining ring (82) is made integrally with the cup (58).

16. The assembly of claim 12 or 13, wherein, The lower seat (88) is axially fixedly mounted relative to the cup (58).

17. The assembly of claim 16, wherein, A gasket (120) is axially interposed between the cup (58) and the lower seat (88).

18. The assembly of claim 16, wherein, The lower seat (88) is made integrally with the cup (58). The lower seat (88) is made integrally with the cup (58).

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