Turbine module for a propeller having variable pitch blades and turbine comprising the module

Abstract

The present invention relates to a turbine module (1), comprising: a rotating housing (7-8) supporting a propeller provided with a plurality of blades (5), a system for varying the pitch of the propeller blades (5), the system comprising a control device, and a mechanism for varying the pitch of the propeller blades, characterised in that the system is supported by the rotating housing (7-8), wherein the control device comprises an annular row of rotary actuators (16), and wherein the mechanism for varying the pitch of the blades comprises a synchronising ring (11), which is driven in rotation by a rotary output shaft (17) of the actuator (16), the synchronising ring (11) being guided in rotation relative to the rotating housing (7-8) by a guide device and meshing with a pinion (14) of the blades (5) via a first tooth (13).

Description

Technical Field

[0001] The present invention relates to a variable pitch propeller for a turbomachine, whether the rotor is shrouded or not. The invention focuses more specifically on the mechanism for controlling the pitch of the blades of these propellers. Background Art

[0002] The background art includes in particular documents US 10288087 B2 and US 8371105 B2.

[0003] It is known that the bypass ratio of a twin-flow engine, whether a turboprop engine or one with an unshrouded propeller, is increased to improve its propulsion efficiency and reduce its specific consumption. This characteristic allows for an increase in the engine's bypass ratio, but also has the disadvantage of operating at reduced fan or propeller speed, which reduces the engine's compression ratio and thus creates aerodynamic instabilities, such as a reduction in pumping margin.

[0004] One solution to resolve these instabilities is to use variable pitch propellers. Therefore, the pitch changing mechanism becomes a major technical component for these engines.

[0005] Propellers made up of fan blades on turbojets or propellers on open-rotor turbines (with unshrouded propellers) have a large number of blades. Furthermore, the pitch change system must counteract the high forces generated by the size of the blades and the power being transmitted. Furthermore, the system must allow for a wide range of pitch angle variations between the extreme operating positions.

[0006] In addition to systems using a separate actuator for each blade (which creates problems of integration, power supply and regulation complexity of the actuators), various systems are known that use synchronizer rings to vary the pitch of an annular row of blades or vanes as a whole. For example, document FR-A1-2 937 678 describes a system using a rotating ring driven by a cylinder in a plane transverse to the longitudinal axis, while document FR-A1-2 997 724 describes a system using a ring driven by the axial translation of a longitudinal cylinder.

[0007] Known systems present various problems of overall size, complexity of regulation or, in particular in the case of hydraulic actuators, of delivering energy to the various actuators.

[0008] The object of the present invention is to respond to the problem of integration in the space of the hub of the propeller, the problem of delivering energy to the actuator or actuators, as well as enabling precise adjustment of the pitch of the blades and compensation of any manufacturing play.

[0009] The second objective is to minimize the impact of installing the pitch changing mechanism on the modularity of the engine and its maintenance.

[0010] The solution also aims to improve the reliability of the system, in particular in the event of actuator failure. Summary of the Invention

[0011] To this end, the invention relates to a module for a turbomachine having a longitudinal axis, comprising:

[0012] a rotating housing rotatable about a longitudinal axis and supporting a propeller provided with a plurality of blades,

[0013] - A system for varying the pitch of the blades of a propeller, the system comprising:

[0014] o Control devices; and

[0015] A mechanism for changing the pitch of propeller blades.

[0016] The invention is notable in that the system is supported by a rotating housing, wherein the control means comprise an annular row of rotary actuators distributed around the longitudinal axis, and wherein the mechanism for varying the pitch of the blades comprises a synchronizing ring rotatably driven by a rotary output shaft of the actuators, the synchronizing ring being rotatably guided relative to the rotating housing by means of a guide means and meshing with a pinion of the blades via a first toothing.

[0017] The use of synchronizer rings enables the pitch of all blades to be varied in a synchronized manner.

[0018] The fact that the synchronizing ring can be rotatably guided on the rotating housing enables the assembly of the rotating mechanism comprising the rotating housing and the blades to be formed as a functional assembly as close to the blades with reduced overall dimensions. This facilitates integration of the assembly on the turbine.

[0019] Furthermore, the rotational guidance of the ring on the rotating housing contributes to the rigidity of the mechanism, allowing for precise blade pitch. Added to this, the fact that the synchronizer ring drives the blades via the gears on the pivots, the device ensures very good relative tolerances of the blade pitch thanks to the precision of the gear meshing.

[0020] Furthermore, these characteristics make it possible to lock, as close as possible to the mounting interface of the blade, all the kinematics and to block the position of this blade in an emergency.

[0021] With respect to the size of the actuator, the torque that the actuator must provide can be minimized by adjusting the geometrical parameters of the ring gear and its teeth.

[0022] Finally, the use of an annular row of multiple actuators meshing on the same synchronizing wheel enables continued operation by the remaining actuators in the event of a failure of one actuator. This improves reliability in the event of a failure. Furthermore, within the scope of the actuation strategy, this arrangement can allow rotation between powered actuators to allow the remaining actuators to cool, a crucial aspect for electric actuators.

[0023] Preferably, the synchronizer ring is surrounded by a hub belonging to the rotating housing and supporting the blades.

[0024] This arrangement corresponds to a compact layout of modules that are easier to integrate and more robust to ensure the accuracy of the pitch of the blades.

[0025] Advantageously, the synchronizer ring comprises a radially outer peripheral edge cooperating with at least one bearing supported by said rotating housing so as to form said rotation guide means.

[0026] By shifting the guiding means to the periphery of the synchronizer ring, the lateral forces and torques applied to retain the synchronizer ring are distributed over a relatively large surface area. This contributes to the robustness and rigidity of the device.

[0027] Advantageously, the output shaft of the actuator has an axis of rotation which is substantially parallel to said longitudinal axis.

[0028] Advantageously, the actuator is supported by a wall of said rotary housing, which wall is substantially perpendicular to said longitudinal axis.

[0029] Preferably, the first teeth for meshing with said pinion of the blade are frustoconical.

[0030] Advantageously, the pinion of the blade is a conical pinion which is directly attached to the root of the blade.

[0031] Preferably, the synchronizer ring includes second teeth which are cylindrical and mesh with the output rotary shaft.

[0032] Preferably, said second teeth are positioned on the radially inner peripheral edge of the synchronizer ring.

[0033] The invention also relates to an aircraft turbomachine comprising at least one module as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other features and advantages of the present invention will become apparent from the following detailed description and reference is made for an understanding of the same to the accompanying drawings, in which:

[0035] [ Figure 1 ] Figure 1 Schematically shows an axial half-section of a module according to the invention;

[0036] [ Figure 2 ] Figure 2 The different pitch positions of the blades of the propeller using the present invention are schematically shown in circumferential section;

[0037] [ Figure 3 ] Figure 3 Shows the use Figure 1 a schematic longitudinal half-section of a turbine of the open rotor type of the apparatus; and

[0038] [ Figure 4 ] Figure 4 Shows the use Figure 1 Schematic longitudinal half-section of a turbine of an apparatus with a shrouded fan. DETAILED DESCRIPTION

[0039] Figure 1 The present invention shows an overall view of an embodiment of a device 1 according to the present invention, which is rotatably driven about the longitudinal axis X of the turbine by a shaft 2 extending from the engine portion (not shown). The shaft 2 itself is rotatably guided on a stationary housing 3 of the turbine via bearings 4. A propeller is arranged in front of the engine. The propeller's blades 5 are rotatably driven about the longitudinal axis X and are each designed to have a variable pitch about a radial axis Y that rotates with the propeller. A cover 6 shields the device from the airflow in which the propeller blades 5 operate.

[0040] Device 1 includes a trunnion 7 centered on longitudinal axis X, which connects shaft 2 to a propeller hub 8, which supports blades 5. Trunnion 7 includes a generally cylindrical center portion 7a that fits onto shaft 2. A splined connection 9 allows trunnion 7 to be installed and removed from the front of shaft 2. This connection is held in place axially by a nut. Trunnion 7 includes a disk 7b, which roughly corresponds to the splined connection 9 and is connected to hub 8. Disk 7b is positioned forward of hub 8. Bolted connections allow hub 8 to be centered and attached to the periphery of disk 7b. Hub 8 is a structural component comprising an annular row of circular housings around its periphery, each housing having known, but not yet fully described, means, such as roller bearings, for mounting a pivot shaft 10 that rotates with blades 5 about radial axis Y. Trunnion 7 and hub 8 form the rotating housing that connects propeller blades 5 to engine shaft 2.

[0041] In order to produce the pitch changing mechanism, a synchronizer ring 11 is mounted on the trunnion 7. The synchronizer ring 11 is here formed by a disk 11a which supports a cylindrical tab 11b on its back side.

[0042] A synchronizer ring 11 is mounted between the disk 7b of the trunnion and the pivot 10 of the blade 5, beneath the hub 8. The periphery of the disk 11a of the synchronizer ring 11 is held in a bearing 12, beneath the hub 8, attached to the periphery of the disk 7a of the trunnion 7. This bearing 12 comprises means (not described in detail here), specifically grooves and roller bearings, which maintain the synchronizer ring 11 centered about the axis X and in a defined axial position. The outer periphery of the disk 11a of the synchronizer ring 11 forms a track for the roller bearings of the bearing 10. These means thus enable the synchronizer ring 11 to rotate freely relative to the trunnion 7 about the longitudinal axis X, while simultaneously withstanding the forces to which it is subjected, thereby maintaining its axial position.

[0043] The cylindrical tabs 11b of the synchronizer ring 11 support a toothed ring 13 at their free ends. The surface of the teeth supporting this ring 13 is frustoconical about the axis X, following a cone whose generatrix passes through the intersection of the plane of axis X and the axis Y of the pivot 10 of the blade 5. The toothed ring 13 meshes with the teeth of a conical pinion 14 attached to the end of the pivot 10 of each blade 5. The surface of the teeth of the pinion 14 supporting each pivot 10 follows a cone centered on the pivot axis Y, whose generatrix passes through the intersection of the plane of axis X and the axis Y of the pivot of the blade 5.

[0044] The precision of the meshing of the synchronizer ring 11 with the conical pinion 14 enables a good accuracy of the blade-to-blade pitch to be obtained with very low relative errors.

[0045] Furthermore, the disk 11a of the synchronizer ring 11 comprises a central groove. On the periphery of this central groove the disk supports an inner axial toothed ring 15.

[0046] The device also comprises an annular row of rotary actuators 16 having an axis Z parallel to the axis X of the turbine, one of which is Figure 1 As shown. Rotary actuators 16 are attached to the disk 7b of the trunnion 7, in front of this disk. Each rotary actuator drives an output shaft 17 in rotation about its axis Z, which passes through the disk 7b of the trunnion and supports a toothed wheel 18 that meshes with the internal toothed ring 15 of the disk 11b of the synchronizer ring 11.

[0047] For example, eight actuators 16, identical to those shown, are attached to the disk of the trunnion, distributed circumferentially in a ring in front of the trunnion. The number of actuators and their sizes can vary depending on the geometric parameters of the device and the individual power set for each actuator. The number of actuators can typically be three, six, or twelve.

[0048] These actuators are electric. Rotary power transmission devices 19 are mounted behind the trunnion 7, between the shaft 2 and the stationary casing 3 of the turbine. Wires 20 transmit the energy from these devices 19 to the actuators 16. The wires are controlled in their position around their axis of rotation Z by electrical pulses.

[0049] Alternatively, a hydraulic actuator may be used. In this case, a rotary hydraulic transmission device must be installed between the fixed structure and the device to provide power and control the fixed structure and the device.

[0050] This assembly forms a module for supporting the blades 5 of the propeller and controlling the pitch angle, the overall dimensions of which are reduced to a small volume at the level of the hub 8 of the blades 5 of the propeller.

[0051] Trunnion 7 and the hub of propeller 8 form a housing that rotates at the speed of propeller shaft 2. Actuator 16 is controlled to rotate its output shaft 17 at the same speed and by the same amount in a given direction, depending on the desired pitch angle. The rotation of output shaft 17 causes synchronization ring 11 to rotate in the reference frame of the rotating housing and, through the meshing of synchronization wheel 11 on pinion 14 of blade 5 pivot shaft 10, results in a corresponding modification of the pitch of each blade 5 about axis Y of that blade's pivot shaft 10.

[0052] In the event of a failure of one actuator, this arrangement allows continued operation via the other actuator by oversizing the actuator. Alternatively, within the scope of the actuation strategy, this arrangement can allow rotation between powered actuators to allow the other actuators to cool. This is an important point for electric actuators.

[0053] The kinematics of the assembly enable the pitch angle to be adjusted over a large angular range. Figure 2 Different angular positions of the blades 5 are shown, namely for feathering C1 , climb C2 , take-off C3 , ground C4 and reverse thrust C5 operating modes. The variation of the pitch angle between the extreme positions is greater than 90°.

[0054] Furthermore, the rigidity of the assembly, in particular due to the bearings for rotatably guiding the synchronizer ring 11 on the trunnion 7 and by the connection through the meshing on the teeth 13 and 15, makes it possible to lock the entire kinematics and block the pitch position of the blade 5 in an emergency, if necessary. The additional device mounted on the trunnion 7 to perform this locking function in the event of an actuator failure is not described here.

[0055] The above-mentioned device can be installed, for example, on a turbine 21 of the "open rotor" type. Figure 3The device 1 is shown arranged below a propeller 22 upstream of such a turbine 21, with a fixed blade ring 23 behind the propeller which rectifies the flow through the propeller 22 and the engine 24 itself (not illustrated in detail) which drives the propeller 22 via the shaft 2. Similarly, with reference to Figure 4 , the device 1 can be installed to drive a hood fan 25 of a double-flow turbine 26, the engine 27 of which is not shown in detail.

Claims

1. A module (1) for a turbomachine having a longitudinal axis (X), the module comprising: a rotating housing (7-8) capable of rotating about said longitudinal axis (X) and supporting a propeller provided with a plurality of blades (5), - a system for varying the pitch of the blades (5) of the propeller, said system comprising: o Control devices; and a mechanism for changing the pitch of the blades of the propeller; Characterized in that the system is supported by the rotating housing (7-8), wherein the control device comprises an annular row of rotary actuators (16) distributed around the longitudinal axis (X), and wherein the mechanism for varying the pitch of the blades comprises a synchronizing ring (11) which can be rotationally driven by a rotary output shaft (17) of the rotary actuator (16), the rotary output shaft (17) of the rotary actuator (16) having a rotation axis (Z) substantially parallel to the longitudinal axis (X), the synchronizing ring (11) being rotationally guided relative to the rotating housing (7-8) by means of a rotary guide device and meshing with a pinion (14) of the blade (5) via a first tooth (13).

2. The module (1) according to claim 1, wherein The synchronizer ring (11) is surrounded by a hub (8) belonging to the rotating housing and supporting the blades (5).

3. The module (1) according to claim 2, wherein The hub (8) comprises an annular row of circular housings around its periphery, each housing a pivot (10) that rotates with the blade (5) about a radial axis (Y).

4. Module (1) according to claim 2 or 3, wherein The rotating housing comprises a trunnion (7) centered on the longitudinal axis (X), the trunnion being used to connect the shaft (2) of the turbine to the hub (8) of the propeller, the hub supporting the blades (5), the trunnion (7) comprising a substantially cylindrical central portion (7a) for fitting onto the shaft (2) and a first disk (7b) connected to the hub (8), the synchronizing ring (11) being mounted on the trunnion (7).

5. The module (1) according to any one of claims 1 to 3, wherein The synchronizer ring (11) comprises a radially outer peripheral edge cooperating with at least one bearing (12) supported by the rotating housing (7-8) to form the rotation guide means.

6. The module (1) according to claim 4, wherein The synchronizer ring (11) comprises a radially outer peripheral edge cooperating with at least one bearing (12) supported by the rotating housing (7-8) to form the rotation guide means, the synchronizer ring (11) being formed by a second disc (11a), the periphery of the second disc (11a) of the synchronizer ring (11) being held in a bearing (12) below the hub (8), the bearing being attached to the periphery of the first disc (7b) of the trunnion (7).

7. The module (1) according to claim 6, wherein The second disc (11a) supports a cylindrical tab (11b) on its back side, and the cylindrical tab (11b) of the synchronizer ring (11) supports a first tooth (13) that meshes with a pinion (14) of the blade (5).

8. The module (1) according to any one of claims 1 to 3, wherein The rotary actuator (16) is supported by a wall of the rotary housing, which wall is substantially perpendicular to the longitudinal axis (X).

9. The module (1) according to any one of claims 1 to 3, wherein The first teeth (13) for meshing with the pinion (14) of the blade (5) are frustoconical.

10. The module (1) according to any one of claims 1 to 3, wherein The pinion (14) of the blade (5) is a conical pinion which is directly attached to the root of the blade (5).

11. The module (1) according to any one of claims 1 to 3, wherein The synchronizer ring (11) comprises second teeth (15) which are cylindrical and mesh with the rotary output shaft (17).

12. The module (1) according to claim 11, wherein The second teeth (15) are positioned on the radially inner peripheral edge of the synchronizer ring (11).

13. An aircraft engine (21, 26) comprising at least one module (1) according to any one of claims 1 to 12.

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