Variable pitch fan

Abstract

The invention relates to a device with fixed actuators for a system (2) for controlling the orientation of the fan blades of a turbomachine, comprising: at least one actuator body (22) housed inside a ring-shaped casing (20) forming a bearing support of the turbomachine, the ring-shaped casing (20) being centered on and inclined with respect to the longitudinal axis (X-X) of the turbomachine, the actuator body (22) having an internal volume in which a piston (30) is able to slide, separating the internal volume into two chambers (22a, 22b) isolated from each other, and a plurality of actuator rods (42) passing through the ring-shaped casing (20) forming the bearing support and each having one end fixed to the piston (30) and the other end for connecting to the inner ring (14) of a motion transmission bearing (10) to drive its translation, the internal volume of the actuator body (22) being closed downstream by a chamber bottom (32) forming a single piece with the ring-shaped casing (20) forming the bearing support.

Description

TECHNICAL FIELD

[0001] The present invention relates to the general field of turbomachines equipped with one or two ducted or non-ducted fans, and more particularly to an actuator cylinder chamber capable of controlled setting of the pitch of the fan blades of these turbomachines.

[0002] The present invention aims to provide a pitch control device with an attached actuator cylinder that optimizes the integration of the actuator cylinder chamber. BACKGROUND

[0003] Pitch control systems are known that make it possible to set the orientation of the blades forming a propeller of a turbojet engine in order to set, by means of an actuator cylinder device, the thrust provided according to the environment.

[0004] Patent application FR3046407 describes a ring actuator of a pitch control system, the body of which comprises a bearing support and on which a chamber bottom is attached. The seal should be ensured by several attachment parts (cover, claw clutch, etc.). If the bearing support deforms, for example when affected by strong unbalance of the fan, the piston can get stuck in the actuator cylinder body.

[0005] Patent US4718823 describes an actuator cylinder device with an actuator cylinder body with an attached chamber bottom, all attached on a bearing support, which adds to the installation operation. Furthermore, this document does not describe a supply system of the actuator cylinder chamber. SUMMARY

[0006] The present invention aims to overcome at least some of the aforementioned drawbacks and to provide an actuator cylinder device system with an attached actuator cylinder body that makes installation simple, that ensures that the actuator cylinder does not get stuck in its chamber, and that makes a good seal between the chamber and the piston.

[0007] In view of the foregoing, the object of the present invention is a device with fixed actuators for a system for controlling the orientation of the fan blades of a turbomachine, the device comprising: at least one actuator body housed inside a ring-shaped casing forming a bearing support of the turbomachine, said ring-shaped casing being centered on and inclined with respect to a longitudinal axis of the turbomachine, each actuator cylinder body comprising an internal volume in which a piston is able to slide, thus separating the internal volume into two chambers isolated from each other; and a plurality of actuator cylinder rods passing through the ring-shaped casing forming the bearing support and each having one end fastened to the piston and an opposite end for connection to the inner ring of a motion transmission bearing to drive its translation, said internal volume of the actuator cylinder body being closed downstream by a chamber bottom that is made in one piece with the ring-shaped casing forming the bearing support.

[0008] Preferably, the internal volume of the actuator cylinder is closed upstream by a wall provided with a plurality of holes through which the actuator cylinder rod passes.

[0009] For example, the actuator cylinder is fixed to the annular casing forming the bearing support by a circular flange surrounding the actuator cylinder.

[0010] Advantageously, this circular flange is screwed onto the annular casing.

[0011] Preferably, the device comprises grooves distributed on the internal profile of the bottom of the chamber.

[0012] Preferably, the device comprises an annular oil circuit centered on the longitudinal axis and surrounding said plurality of actuator cylinder rods, and comprising a through passage forming an oil inlet passing through the annular casing towards the actuator cylinder.

[0013] Advantageously, this annular oil circuit comprises a double oil circulation by two substantially concentric annular passages.

[0014] The device can comprise several actuator cylinders each containing a piston and said actuator cylinders being uniformly distributed around the longitudinal axis of the turbomachine, and each piston being connected to the synchronizing ring by one end of an actuator cylinder rod.

[0015] According to one embodiment, the invention relates to a system for controlling the orientation of the fan blades of a turbomachine, comprising at least one set of fan blades with adjustable orientation, said set being fixed to rotate with a rotating ring, the fan blades being coupled to a motion transmission bearing for pivoting the pivoting axis of the fan blades around their radial axis in order to adjust the orientation of the fan blades, said motion transmission bearing comprising an inner ring connected to a device as previously described.

[0016] The invention also relates to a method for installing this device, comprising: starting from the propeller shaft previously mounted on the main casing of the turbomachine by means of a rolling bearing, assembling each actuator cylinder formed by an actuator cylinder rod and a piston mounted on an actuator cylinder, said assembly being performed by housing each actuator cylinder one after the other inside the casing forming the bearing support and assembling this assembly on the main casing of the turbomachine and the propeller shaft. BRIEF DESCRIPTION OF DRAWINGS

[0017] The invention will be better understood by a detailed study of some embodiments considered as non-limiting examples and illustrated by the attached drawings in which:

[0018] Figure 1 is a sectional view of a fixed actuator cylinder device according to the invention in its environment.

[0019] Figure 2 is Figure 1 a partial perspective view of the device in

[0020] Figure 3 is a sectional view of the actuator cylinder chamber formed in the housing.

[0021] Figure 4 is a first sectional view of the actuator cylinder chamber, in which the actuator cylinder body receiving the actuator cylinder is housed.

[0022] Figure 5 is a second sectional view of the actuator cylinder chamber, in which the actuator cylinder body receiving the actuator cylinder is housed. DETAILED DESCRIPTION

[0023] The present application is applicable to any turbomachine equipped with at least one ducted or unducted fan, and whose propeller blades (in the case of unducted fans) or fan blades (in the case of ducted fans) are equipped with a variable-pitch system. In particular, the present application is applicable to turboprop engines having one or more propelling propellers, and to turbojet engines having propellers (known as "open-rotor") or two counter-rotating propellers placed upstream ("tractor" version) or downstream ("pusher" version) of the gas generator.

[0024] The present application is also applicable to turbomachines having ducted fans.

[0025] The structure of these types of turbomachines is known to the person skilled in the art, and therefore will not be described in detail here. In summary, these turbomachines comprise one or more propellers (in the case of turbomachines having unducted fans) or fans (in the case of turbomachines having ducted fans), each comprising a set of fan blades (or blades) having a variable pitch angle, i.e. whose orientation can be changed by the system for controlling the orientation of the blades described below.

[0026] Figure 1 Partially shown is a device 1 according to the present application, comprising an example of a system 2 for controlling the orientation of the propeller blades of a turbomachine having unducted fans.

[0027] Of course, in the case of turbomachines having ducted fans, the principles of the present application described below apply in the same way to the fan blades.

[0028] The control system 2 comprises a rotating ring 4 (or hub) which is centred on the longitudinal axis X-X of the turbomachine, and which is provided with an aperture 6 through which the pivoting shaft 8 of the fan blades is mounted (not shown in the figures).

[0029] Each pivot shaft 8 is coupled to a motion transmission bearing 10, also called LTB for "Load Transfer Bearing", so as to set the orientation of the corresponding blade, the motion transmission bearing serving to pivot said pivot shaft about its radial axis Z-Z.

[0030] To this end, the motion transmission bearing 10 comprises an outer ring 12 and an inner ring 14, centered on the longitudinal axis X-X of the turbomachine, translatable along this axis X-X, and defining raceways for the bearing, here two rows of angular contact balls 16, to transmit axial forces in both directions.

[0031] The outer ring 12 of the motion transmission bearing is coupled, directly or indirectly, to the radially inner end of the pivot shaft, for example by means of a lever arm 18.

[0032] When the inner ring of the motion transmission bearing is axially moved under actuation of the actuator cylinder device, it causes the lever arm and, by virtue thereof, the pivot shaft 8 to pivot in the aperture 6 of the rotating ring about their radial axis Z-Z, thereby causing the pivoting of the fan blades.

[0033] Downstream of the actuator cylinder device, the turbomachine also comprises a main casing 19 carrying a ball bearing 21 for supporting in rotation a propeller shaft 23 supporting the rotating ring 4.

[0034] Preferably, this propeller shaft 23 is driven by the turbomachine and a reduction gear (not shown in the figures).

[0035] An annular casing 20 is fastened on this main casing 19, centered on the longitudinal axis X-X of the turbomachine and inclined with respect to the longitudinal axis X-X of the turbomachine by an angle generally greater than 30 degrees (this inclination being oriented so that the casing 20 has a shape similar to a cone with an opening downstream).

[0036] Generally, this casing 20 serves as a support for a rolling bearing 24 for guiding the rotation of the rotating ring 4.

[0037] To this end, the casing 20 carries an outer ring 24a of the rolling bearing 24, the inner ring 24b of which is fixed to the rotating ring 4.

[0038] Furthermore, the casing 20 and the rotating ring 4 delimit between them an oil chamber 25 which accommodates the actuator cylinder device 1.

[0039] This oil chamber 25 is pressurized under vacuum so that the oil does not escape.

[0040] In order to limit the leakage flow rate leaving the oil chamber, it is in particular provided that a sealing washer 27 is provided between the shroud 23a of the propeller and the main casing 19, downstream of the pivot shafts of the fan blades.

[0041] Leakage can occur at the orifice 6 of the rotating ring 4 of the pivot shaft of the fan blades.

[0042] Nevertheless, these leakages are compensated for by the seals of the oil chamber.

[0043] Furthermore, this oil chamber 25 extends downstream of the rolling bearing 21 and can 10 contain the seals between the reducer and the different shafts.

[0044] According to the invention, the actuator cylinder device 1 for ensuring the pivoting of the fan blades comprises in particular an annular actuator cylinder 22, which is centered on the longitudinal axis X-X of the turbomachine and is housed in the space delimited by the housing 20 forming the bearing support.

[0045] As Figure 3 illustrated, unlike the actuator cylinder which, in the prior art, is integral with the housing 20, the actuator cylinder 22 is a component attached to the housing 20.

[0046] The actuator cylinder 22 delimits an internal volume in which the piston 30 is able to slide, thus separating the internal volume of the actuator cylinder into two chambers isolated from one another, namely an upstream chamber 22a and a downstream chamber 22b.

[0047] A plurality of pistons can be provided, which are independent or each connected by their rod to a synchronizing ring.

[0048] This synchronizing ring serves as a synchronizer for the pistons 30, enabling them to slide within the internal volume of the actuator cylinder 22 under the effect of the hydraulic fluid (not shown) injected under pressure into either the upstream chamber or the downstream chamber.

[0049] As Figure 4 illustrated, the internal volume of the actuator cylinder 22 is closed upstream by a wall 26 provided with a plurality of holes 28 through which the actuator cylinder rods 42 pass. These holes 28 are distributed around the longitudinal axis X-X of the turbomachine.

[0050] Furthermore, the internal volume of the actuator cylinder 22 is closed downstream by a chamber bottom 32, unlike the chamber bottom of the known devices, which is integral with the annular housing 20 forming the bearing support.

[0051] Having the bottom of the chamber 32 entirely in the material of the annular housing 20 makes it possible to overcome the difficulty of adding a closure attached directly opposite the piston to the housing 20. In particular, the attached chamber bottom creates sealing difficulties and premature wear, whereas its integration with the housing increases its mechanical resistance to the high hydraulic stresses in the chambers 22a, 22b.

[0052] In addition, the bottom of the attached chamber requires a specific arrangement for sealing the internal volume of the actuator cylinder, for example, at its inner circumference, in order to ensure a seal for the internal volume of the actuator cylinder in which significant oil pressure exists.

[0053] The actuator cylinder 22 can be fixed to the annular housing 20 forming the bearing support by means of the circular flange 31 covering the actuator cylinder 22.

[0054] The circular flange 31 is screwed onto the annular housing 20, for example, by a series of holes distributed in a circle around the longitudinal axis of the turbine at the outer periphery of the flange 31, and screws (not shown in the figure) pass through these holes to reach threads disposed opposite to each other on the housing.

[0055] As in Figure 2 As shown, the actuator cylinder device 1 according to the invention also includes a plurality of actuator cylinder rods 42, which are mounted through holes in the wall 26 of the actuator cylinder body.

[0056] Preferably, these actuator rods are evenly distributed around the longitudinal axis XX of the turbine to apply the required pitch control force.

[0057] The number of actuator rods is a trade-off between the force to be transmitted directly through each rod (which affects the cross section of each rod) and the number of rods (which affects the weight of the system).

[0058] Preferably, there are at least four rods to distribute the force acting on the piston.

[0059] Each actuator rod 42 has a downstream end and an upstream end, the downstream end being fastened to a piston 30, which is connected to a synchronizing ring 34 of the actuating cylinder via the actuator rod 42, and the upstream end being connected to the inner ring 14 of the motion transmission bearing 10 to drive its translation.

[0060] The actuator rods can be fastened to each piston 30 by means of nuts 44, which are screwed onto the downstream end of the rods, which are threaded.

[0061] Similarly, the actuator rod 42 is connected at its upstream end to the inner ring 14 of the motion transmission bearing by a screw 46 extending in the radial direction. Figure 1 ).

[0062] In the case of multiple actuator cylinders 22 ( Figure 3 , Figure 4 and Figure 5 The synchronization ring function can be performed by the inner ring 14, or, in the case of a single actuator cylinder with an annular shape ( Figure 2 The synchronization ring function can be performed by a synchronization ring different from the inner ring 14 and formed by a single piston 30.

[0063] As Figure 4 and Figure 5 shown, the device 1 comprises an annular oil circuit 29 centered on a longitudinal axis X-X and surrounding the plurality of actuator cylinders 42.

[0064] The use of several actuator cylinders 42 makes it possible to ensure redundancy of their functioning.

[0065] Furthermore, the maintenance of the actuator cylinders is facilitated: the latter are no longer buried under the fan hub, but are now easily accessible on the bearing support. Furthermore, in the event of maintenance, the actuator cylinders can be replaced individually.

[0066] The oil circulation in the oil circuit 29 is supplied from the oil chamber 25 and passes to the actuator cylinder body 22 thanks to the through passage 29c formed which passes through the annular housing 20 towards the oil inlet of the actuator cylinder body 22.

[0067] The through passage 29c is transverse to the radial axis of the device 1 and is directed towards the chamber bottom 32.

[0068] The housing 20 comprises an annular widening 41 of the passage 29c up to the chamber bottom 32 which makes it possible for the oil to flow towards the chamber bottom 32.

[0069] The chamber bottom 32 makes it possible to flow back the oil towards the piston 30. Thus, each chamber bottom 32 associated with an actuator cylinder makes it possible to supply oil to this actuator cylinder.

[0070] As shown, according to the section of Figure 1 , the annular widening 41 can form a space with a substantially rectangular section between the housing 20 and the actuator cylinder body 22.

[0071] Furthermore, the chamber bottom 32 can comprise grooves 33 distributed on the internal profile of the chamber bottom 32. Figure 3 .

[0072] The grooves 33 delimit recesses making it possible for the oil from the opening 29c and from the widening 41 to enter the downstream chamber 22b between the piston 30 and the chamber bottom 32, in particular when the piston 42 abuts against the grooves 33.

[0073] The grooves 33 also make it possible to ensure that the chamber bottom 32 is not blocked (foreign bodies or dirt can be lodged between the grooves rather than above), making it possible for the stroke of the actuator cylinder 42 not to be blocked.

[0074] The annular oil circuit 29 can comprise a double oil circulation by two substantially concentric annular passages 29a, 29b.

[0075] In particular, two complementary oil circuits 29a, 29b can be used, each oil circuit supplying one half of the actuator cylinder 42, to ensure the system against the event of failure of one of the two oil systems.

[0076] For example, the two annular channels 29a, 29b are superimposed, for optimizing the compactness of the device 1. Each one can also have a substantially trapezoidal section, in particular a rectangular section.

[0077] The two annular channels 29a, 29b, i.e. the one closest and the one farthest radially to the X-X axis, are respectively used to implement the circulation of oil between the various actuator cylinders 24 and to supply the chamber bottom 32 via the bearing support.

[0078] In this case, the radially closest duct is thus the one leading to the through channel 29c.

[0079] The operation of the actuator cylinder device 1 obviously follows what has been described above.

[0080] To continue adjusting the orientation of the pivot shaft of the fan blades 8, hydraulic fluid is injected under pressure into either of the upstream chamber 22a and the downstream chamber 22b of the chamber, which causes each piston 30 (and the synchronization ring, if one is present to which all the pistons 30 are linked) to move along the longitudinal axis X-X of the turbomachine. The rods 42 then translate axially in a synchronized manner, so that the motion transmission bearings move upstream or downstream. In turn, this translation of the bearings causes the pivoting of the lever arms 18, resulting in the synchronized pivoting of the fan blades.

[0081] The installation of the actuator cylinder device according to the invention is as follows.

[0082] In a first step, the propeller shaft 23 is assembled to the reducer and the rolling bearing 21 (and its support) is assembled to the main casing 19 of the turbomachine. Then, the actuator cylinder rods 42 and the pistons 30, taken successively or mounted on a synchronization ring, are assembled on the actuator cylinder body 22 and on the casing 20 forming the bearing support.

[0083] Thereafter, the group formed by the actuator cylinder rods 42, the pistons 30, taken independently or mounted on a synchronization ring, the actuator cylinder body, the casing forming the bearing support, and the rolling bearing 24 can be taken axially upstream- downstream to assemble it on the main casing 19 and 15 propeller shaft 23 of the turbomachine.

[0084] The motion transmission bearings 10 are then assembled with the actuator cylinder rods 42.

[0085] Thereafter, the downstream casing 23a of the propeller is assembled with the rotating ring 4 and the pivot shaft of the fan blades is mounted on this downstream casing.

[0086] The stud of the pivot shaft of the fan blade and of the filler rod arm 18 is screwed to join the pivot shaft to the motion transmission bearing 20.

[0087] Finally, the upstream propeller housing 23b is assembled 23c to the propeller shaft 23 and to the rotating ring 4 by means of splined connections.

[0088] The disassembly of the actuator cylinder device is performed in the opposite manner.

[0089] The device 1, which serves as a bearing support, is thus assembled, integrating a particularly compact and resistant chamber bottom and oil circulation.

[0090] Furthermore, the bearing support is advantageously designed to enable printing using 3D printing technology of the "powder bed fusion" type ("laser bed fusion"). This makes it possible to produce the part as a single piece and to integrate the oil circulation circuit 29.

Claims

1. A device (1) having a fixed actuator for a system (2) for controlling the orientation of fan blades of a turbine, said device (1) comprising: At least one actuator cylinder (22) is housed within an annular housing (20) of a support forming a motion transmission bearing (10) of the turbine, the annular housing (20) being centered on and inclined relative to the longitudinal axis (XX) of the turbine, each actuator cylinder (22) comprising an internal volume in which a piston (30) is slidable, thereby dividing the internal volume into two isolated chambers (22a, 22b); And at least one actuator rod (42) passing through the annular housing (20) forming a support for the bearing (10), and each actuator rod (42) having one end fastened to the piston (30) and an opposite end for connecting to the inner ring (14) of the bearing (10) to drive its translation, characterized in that the internal volume of the actuator cylinder (22) is closed downstream by a chamber bottom (32) integrally formed with the annular housing (20) forming the support for the bearing (10).

2. The apparatus (1) according to claim 1, wherein, The internal volume of the actuator cylinder (22) is sealed upstream by a wall (26) with a plurality of holes (28) through which the actuator cylinder rod (42) passes.

3. The apparatus (1) according to any one of the preceding claims, wherein, The actuator cylinder (22) is fixed to the annular housing (20) forming the bearing support by a circular flange (31) surrounding the actuator cylinder (22).

4. The apparatus (1) according to claim 3, wherein, The circular flange (31) is screwed onto the annular housing (20).

5. The device (1) according to any one of the preceding claims includes grooves (33) distributed on the inner contour of the bottom (32) of the chamber.

6. The device (1) according to any one of the preceding claims includes an annular oil passage (29) centered on the longitudinal axis (XX) surrounding the plurality of actuator cylinder rods (42), and includes a through channel (29c) forming an oil inlet through the annular housing (20) toward the actuator cylinder (22).

7. The apparatus (1) according to claim 6, wherein, The annular oil passage (29) includes a dual oil circulation through two generally concentric annular channels (29a, 29b).

8. The device (1) according to any one of the preceding claims comprises a plurality of actuator cylinders (22), each actuator cylinder housing a piston (30), and the actuator cylinders (22) are uniformly distributed around the longitudinal axis (XX) of the turbine.

9. A system (2) for controlling the orientation of fan blades of a turbine, comprising a device (1) according to any one of claims 1 to 8 and at least one set of fan blades having an adjustable orientation, the set being fixed and rotating together with a rotating ring (4), the fan blades being coupled to a motion transmission bearing (10) for adjusting the orientation of the fan blades, the motion transmission bearing (10) being used to pivot the pivot axis (8) of the fan blades about their radial axis, the motion transmission bearing including an inner ring (14) connected to the device (1).

10. A method for installing the device according to any one of claims 1 to 8, comprising: Starting with the propeller shaft (23) pre-mounted on the turbine main housing (19) via rolling bearings (21), each actuator cylinder is assembled from the at least one actuator cylinder rod (42) and a piston (30) mounted on the actuator cylinder body (22). The assembly is performed by accommodating each actuator cylinder one after another within the housing (20) forming the bearing support and assembling the assembly on the turbine main housing (19) and the propeller shaft (23).

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