PROPULSION DEVICE FOR AN AIRCRAFT, SUCH AS A TURBOPROP

Abstract

The invention concerns a propulsion device (1) comprising a torque generator (2) driving an output shaft (3) via a power gearbox (4), the output shaft (3) being rotatably coupled to a thruster (5), said power gearbox (4) being fixed on a frame (7) by means of suspension means (8, 14, 15), said suspension means including hydraulic torque recovery means comprising at least a first hydraulic system (15) and a second hydraulic system (15) spaced from each other, each hydraulic system (15) having a pressure chamber whose volume varies according to the position of the housing (9) of the power gearbox (4) relative to the frame (7), the pressure chambers of the hydraulic systems (15) being connected by a capillary so that a hydraulic fluid is able to flow from one pressure chamber to another via the capillary.

Claims

1.-9. (canceled)

10. A propulsion device (1) for an aircraft, such as a turboprop, comprising a torque generator (2) driving an output shaft (3) via a power gearbox (4), the output shaft (3) being rotatably coupled to a propeller (5), said power gear box (4) being fixed on a frame (7) by means of suspension means (8, 14, 15), said suspension means including hydraulic torque recovery means comprising at least a first hydraulic system (15) and a second hydraulic system (15) spaced from each other, each hydraulic system (15) including a pressure chamber (18a, 18b) whose volume varies according to the position of the housing (9) of the power gearbox (4) relative to the frame (7), the pressure chambers (18a, 18b) of the hydraulic systems (15) being connected by a capillary (19) so that a hydraulic fluid is able to flow from one pressure chamber (18a) to the other (18b) via the capillary (19), characterized in that it includes means (20) for measuring the pressure of the hydraulic fluid within at least one of the pressure chambers (18a, 18b) and/or within the capillary (19) and means for determining the torque transmitted to the thruster (5) through the output shaft (3), in particular as a function of the pressure of the hydraulic fluid.

11. The propulsion device (1) according to claim 10, characterized in that the suspension means comprise at least one insulator (14) mounted between the frame (7) and the housing (9) of the power gearbox (4).

12. The propulsion device (1) according to claim 10, characterized in that each hydraulic system (15) comprises a cylinder (16) connected to the frame (7) and a piston (17) movably mounted in the cylinder (16) and delimiting with said cylinder (16) the pressure chambers (18a, 18b), the piston (17) being connected to the housing (9) of the power gearbox (4).

13. The propulsion device (1) according to claim 11, characterized in that each hydraulic system (15) comprises a cylinder (16) connected to the frame (7) and a piston (17) movably mounted in the cylinder (16) and delimiting with said cylinder (16) the pressure chambers (18a, 18b), the piston (17) being connected to the housing (9) of the power gearbox (4).

14. The propulsion device (1) according to claim 10, characterized in that the two pressure chambers (18a, 18b) are located on either side of a median axial plane (P) extending along the outlet axis (3).

15. The propulsion device (1) according to claim 10, characterized in that the means for determining the torque transmitted to the propeller (5) are capable of taking into account environmental or operating parameters of the propulsion device (1), such as for example the temperature and/or pressure of the air outside the device (1), altitude, flight parameters, hydraulic fluid temperature.

16. The propulsion device (1) according to claim 10, characterized in that the capillary (19) and/or the pressure chambers (18a, 18b) are designed to measure torque oscillations whose frequency extends up to at least 5 Hz, preferably up to 10 Hz.

17. The propulsion device (1) according to claim 10, characterized in that it comprises at least one chip (22) comprising a memory, for example an RFID chip, in which calibration parameters are stored for integration in the ECU associated with a new torque generator (2), in the event of a change or maintenance of said torque generator (2).

18. A process for determining the torque transmitted to the output shaft of a propulsion device (1) according to claim 10, characterised in that it includes the steps consisting of: (a) measuring the pressure of the hydraulic fluid in the pressure chamber (18a, 18b) and/or capillary (19), (b) determining by calculation the torque transmitted to the propeller (5) through the output shaft (3), in particular according to the pressure of the hydraulic fluid.

19. The method according to claim 18, characterized in that, when starting the device (1) and/or when operating the device (1) in an idle mode, the pressure of the hydraulic fluid is measured in such a way as to define a reference value taken into account in step (b) in order to calculate the torque transmitted to the thruster (5) through the output shaft (3).

Description

[0049] The invention will be better understood, and other details, characteristics and advantages of the invention will appear upon reading of the following description given by way of a non restrictive example while referring to the appended drawings wherein:

[0050] FIGS. 1 and 2 are front schematic views of a propulsion device for an aircraft, according to one embodiment of the invention,

[0051] FIG. 3 is a schematic view, from the front, of a part of the propulsion device.

[0052] FIGS. 1 to 3 illustrate a propulsion device 1 for an aircraft, according to one embodiment of the invention.

[0053] This propulsion device 1 for an aircraft has a torque generator 2 driving an output shaft 3 via a power transmission gearbox 4, the output shaft 3 being rotatably coupled to a propeller 5.

[0054] The torque generator 2 is here a turbomachine, the propeller 5 being a propeller comprising blades 6 equipped with blade adjustment means allowing the angular position of the blades 6 to be adjusted about their axis oriented perpendicular to the output axis 3.

[0055] The torque generator 2 is fixed to a frame or cradle 7, more particularly to a so-called rear frame 7a of frame 7, by means of insulators 8. Frame 7 allows propulsion system 1 to be suspended from an aircraft structure, for example, at a wing or on a pylon attached to the fuselage (not shown).

[0056] Power Gear Box (PGB) 4 is a gearbox designed to reduce the rotational speed of the torque generator shaft 2, so as to drive the output shaft 3 equipped with thruster 5.

[0057] The power gear box 4 has a housing 9 and an epicyclic gearbox comprising a planetary 10 and a gear ring 11, meshing with satellites 12 (FIG. 2). Output shaft 3 is rotationally fixed to a satellite carrier 13, the latter carrying axes around which the satellites 12 are pivotally mounted. The housing 9 is mounted on a so-called front frame 7b of the frame or cradle 7 via insulators 14 and hydraulic systems 15.

[0058] The said insulators 8, 14, make it possible to avoid or limit the transmission of vibrations generated during operation, in particular to reduce noise or fatigue phenomena.

[0059] The insulators 8, 14 here are elastic studs made of elastomer material, forming silentblocs.

[0060] For example, there are three insulators 14 fitted to the front frame 7b and are placed in areas at 9, 12 and 3 o'clock respectively, by analogy with the dial of a clock. In other words, a first insulator 14a (FIG. 3) is placed on an axial median plane P passing through the output axis 3, a second and a third insulator 14b, 14c being placed on either side of said median plane P, symmetrically, as shown in FIG. 3.

[0061] Hydraulic systems 15, two in number and located in areas at 3 and 9 o'clock for example, each have a cylinder 16 in which a piston 17 is movably mounted, the cylinder and piston defining a pressure chamber 18a, 18b.

[0062] Each cylinder 16 is connected to frame 7 or respectively to frame 9 of power gearbox 4, each piston 17 being connected to frame 9 of power gearbox 4 or respectively to frame 7.

[0063] The pressure chambers 18a, 18b are connected by a capillary 19 and filled with a hydraulic fluid so that, when the housing 9 of the power gearbox 4 is moved (particularly when rotating about the outlet axis) relative to frame 7, the hydraulic fluid flows from one pressure chamber 18a to the other 18b through the capillary 19, in the manner of connected vessels. The two chambers 18a, 18b are thus in opposition and the volumes of said chambers 18a, 18b vary simultaneously, the hydraulic fluid opposing rotation about the outlet axis of the housing 9 of the power gearbox 4 with respect to frame 7.

[0064] The hydraulic fluid is for example oil.

[0065] Pressure chamber 18a, pressure chamber 18b and/or capillary 19 are equipped with at least one pressure sensor 20 and/or at least one temperature sensor 21 capable of measuring the pressure and temperature of the hydraulic fluid respectively.

[0066] Pressure sensor 20 is an absolute type sensor or a relative type sensor, the reference pressure being, for example, air pressure outside propulsion device 1.

[0067] Preferably, only one of the pressure chambers 18a, 18b is equipped with a pressure sensor 20 and a temperature sensor 21 grouped together as a single measuring module.

[0068] As previously indicated, the pressure of the hydraulic fluid in pressure chambers 18a, 18b and capillary 19 is a first order function of the torque exerted by the housing 9 of the power gearbox 4 on the frame or cradle 7 of device 1. This torque is representative of the output torque to be determined, i. e. the torque generated at output shaft 3.

[0069] It is therefore possible to determine by calculation, using an algorithm, the output torque from the hydraulic fluid pressure measurement.

[0070] Other parameters may also be taken into account by the algorithm, in particular parameters of the environment or the operation of the propulsion device, such as for example the temperature and/or pressure of the air outside the device, the altitude or the flight parameters.

[0071] Isolators 8, 14 are intended to absorb torque oscillations or high frequency vibrations, for example greater than 10 Hz, and hydraulic systems 15 are intended to counter low frequency torque oscillations, for example between 0 and 10 Hz to avoid excessive static stress on elastic studs. The pressure measurement therefore reflects the value of the static torque at output shaft 3, but is also suitable for measuring torque peaks generated by transient events, provided that these peaks have a bandwidth compatible with that of pressure chambers 18a, 18b and capillary 19. The shape and dimensions of the pressure chambers 18a, 18b of capillary 19 are therefore adapted accordingly, depending on the type of transient event to be detected.

[0072] Propulsion device 1 may include at least one chip 22 (FIG. 1) with a memory, for example an RFID chip, in which calibration parameters are stored for integration into the ECU associated with a new torque generator 2, in the event of a change or maintenance of said torque generator 2. For example, chip 22 is attached to the housing 9 of the power gearbox 4.

[0073] As mentioned above, in the case of a maintenance operation requiring a change of the torque generator 2, the different calibration parameters must be integrated into the ECU associated with a new torque generator 2. The use of such a chip 22 makes this step easier.

[0074] During operation, the torque generator must be regulated. For this purpose, it is equipped with an on-board computer usually referred to as EEC (Electronic Engine Control).

[0075] An important element for such regulation is the calculation of the output torque, i. e. the torque generated at output shaft 3.

[0076] For this purpose, as indicated above, the temperature and pressure measurements of the hydraulic fluid and the above-mentioned parameters of the environment or operation of the propulsion system are used. As indicated above, the calibration curve obtained during the tests is also used to determine the percentage or fraction of the said output torque passing through the hydraulic cylinders 15 and the front frame 7b.

[0077] The invention thus proposes a process and a propulsion device 1 allowing an efficient regulation of the torque generator from the torque generated at propeller 5.