Worm wheel and screw angular adjustment assembly for adjustable orientation vane and associated adjustment method

Abstract

Angular adjustment assembly with wheel and endless screw for variable pitch blade and associated adjustment method One aspect of the invention relates to an angular adjustment assembly (1) for an adjustable orientation blade (6) of a turbomachine or X-axis testing machine, comprising an adjustment device (19) capable of pivoting the blade about a Y axis perpendicular to and intersecting the X axis until the desired angular positioning is reached. The blade comprises at its base (8) a toothed wheel (15) of Y axis, the pivoting of which causes that of the blade. The adjustment device comprises a threaded rod (18) of X' axis parallel to X, engaged with the toothed wheel and the rotation of which about the X' axis causes the toothed wheel to pivot about the Y axis. Figure to be published with the abstract: Figure 2

Description

Title of the invention: Angular adjustment assembly with wheel and worm screw for adjustable orientation blade and associated adjustment method TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of aircraft turbomachines and testing machines for the development of aircraft turbomachines.

[0002] The present invention relates to an angular adjustment assembly for an adjustable orientation blade of a turbomachine or turbomachine testing machine. It also relates to a turbomachine and a turbomachine testing machine comprising such an angular adjustment assembly, as well as an adjustment method using such an angular adjustment assembly. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Aircraft turbomachines often have adjustable-orientation blades, also called variable-pitch blades or pivoting blades. These blades can pivot about their axis, in order to adjust their angular position (their angle of attack) relative to the airflow passing through them and thus optimize the airflow in the turbomachine.

[0004] Stator stages of variable-pitch vanes are thus often found between the moving wheels of turbomachine compressors. These may also be flow straightening vanes located downstream of the fan, called outlet guide vanes or OGV vanes (Outlet guide vanes in English).

[0005] Such blades are carried by a stator casing and can be pivoted during engine operation, which makes it possible to optimize their action according to the engine speed and flight conditions. Since the performance of the turbomachine relies on the precision of the angular positioning of these blades relative to the casing, the adjustment of the angular position must be rapid, precise, reliable and repeatable.

[0006] In the current technique, these variable-pitch blades are extended at their outer end by a radial control rod which passes through an opening in the outer casing. Control rods are fixed laterally to the free ends of these control rods and are connected by their other end to a rotating crown located outside the casing. A servo system, electric, pneumatic or hydraulic, automatically controls the rotation of the crown according to the operating conditions, which causes the pivoting of the rods and thus the modification of the inclination of the variable-pitch blades.

[0007] For this system to be functional, the coupling between the control rod and the connecting rod of a blade must be precise in addition to having to withstand significant torques. In addition, the adjustment during assembly of the orientation of the blade relative to the connecting rod must be particularly fine.

[0008] An objective of the invention is to propose an assembly for alternative angular adjustment of variable-pitch blades, usable in a turbomachine, which is mechanically simpler and which is at the same time rapid, precise, reliable and repeatable.

[0009] Adjustable orientation blades are also found in testing machines for the development of aircraft turbomachines. These testing machines make it possible to test the aerodynamic and acoustic behavior of the various elements of the turbomachine and in particular to determine the optimal angular positioning of the moving blades of the rotors and the fixed blades of the stators to obtain the best possible performance.

[0010] The testing machines therefore conventionally comprise blades with adjustable orientation in order to be able to simulate a precise angular positioning of these blades and / or test different positions depending on the result of the tests.

[0011] Currently, in testing machines, the angular adjustment of variable pitch blades is done manually using complex tools to measure the displacement of the blade and thus position it with the desired pitch angle. This operation is long and meticulous and must be carried out blade by blade by an experienced operator.

[0012] An objective of the invention is to propose an assembly for alternative angular adjustment of variable-pitch blades, usable in a testing machine, which is simple, rapid, precise, reliable and repeatable. Summary of the invention

[0013] A first aspect of the invention relates to an assembly for angular adjustment of an adjustable orientation blade of a turbomachine or of an X-axis turbomachine testing machine.

[0014] This angular adjustment assembly includes: • an adjustable orientation blade, comprising a base and a body extending radially from this base, the adjustable orientation blade being free to pivot about an axis Y perpendicular to and intersecting the axis X; and • a device for adjusting the pivoting of the blade with adjustable orientation around the Y axis.

[0015] According to the invention, the adjustable orientation blade comprises at its base a Y-axis toothed wheel, free to pivot around the Y axis and kinematically linked to the adjustable orientation blade, and the adjustment device comprises a threaded rod X' axis parallel to the X axis, which is engaged with the gear wheel. Thus, the rotation of the threaded rod around the X' axis causes the gear wheel to pivot around the Y axis.

[0016] The expression "kinematically linked" means that the toothed wheel and the blade move together and in the same way, the movement of one being transmitted to the other without modification (they have no relative movement). They can be monobloc (made from a single piece) or fixed to each other.

[0017] This angular adjustment assembly can be used both in an aircraft turbomachine and in an aircraft turbomachine testing machine.

[0018] In a turbomachine, it can, for example, allow the angular position of the outlet guide vanes or the variable-pitch vanes of the compressors to be adjusted in order to adapt their angular positioning to the engine speed and the flight conditions and thus to optimize the operation of the turbomachine.

[0019] In a test machine, it can be used to adjust the angular position of any blade whose angular orientation has been provided to be adjustable in the test machine (this blade being able to be fixed once installed in a turbomachine). Different angular positions of this blade can thus be tested using the test machine and an aerodynamically optimal angular position (an optimal pitch angle) can be defined to be reproduced later in the turbomachine to improve performance.

[0020] The invention provides a reliable and mechanically simple worm gear angular adjustment assembly. It allows the angular position of the blade to be adjusted easily and quickly, without having to dismantle any part to achieve this.

[0021] Furthermore, the adjustment is very precise because the gear has a very high reduction ratio. A complete turn of the threaded rod only causes a rotation of a single tooth for the toothed wheel and therefore a very small angular displacement of the blade concerned. Furthermore, to increase this reduction effect, it is sufficient to increase the number of teeth on the toothed wheel.

[0022] Thanks to this gear reduction effect of the gear system by toothed wheel and worm screw which guarantees high adjustment precision, the adjustment assembly according to the invention also has excellent repeatability which allows it to return to a previous angular position of the blade with increased precision.

[0023] Advantageously, the toothed wheel can be in one piece with the base of the blade with adjustable orientation.

[0024] The base of the blade is thus shaped into a toothed wheel. This simplifies manufacturing. In addition, the precision of the adjustment of the angular positioning of the blade is further improved. Because, with two single-piece parts, the movement is entirely and instantly transmitted between the gear wheel and the blade. This avoids any potential offset between the gear wheel and the blade that could be caused by play between two assembled parts.

[0025] Advantageously, the angular adjustment assembly may further comprise a locking screw which, when tightened, bears against the threaded rod.

[0026] Such a locking screw prevents the threaded rod from rotating when it is pressed tightly against it. The pivoting of the toothed wheel is then impossible and the blade is locked in its angular position. The angular adjustment assembly is thus completely locked.

[0027] The locking or unlocking of the angular adjustment assembly is thus done very simply by screwing or unscrewing this locking screw.

[0028] Other alternative locking systems may be envisaged, for example using a servomotor system, motor, controlled or non-controlled magnet, mechanical lock, in particular of the mechanical grasshopper type, or the like. However, the tight support by locking screw is advantageously the simplest and most economical solution.

[0029] Optionally, this locking at the worm screw level can be supplemented by an additional locking at the blade level.

[0030] Advantageously, the angular adjustment assembly may further comprise a hub which has communicating housings in which the base of the adjustable orientation blade and the threaded rod are housed.

[0031] The hub makes it possible to house both the base of the blade and the threaded rod, while allowing them to cooperate with each other to enable the operation of the gear, via the communication of their respective housing. Thus, the overall size of the angular adjustment assembly is restricted and the gear is protected from the external environment.

[0032] Advantageously, the angular adjustment assembly may further comprise at least one stop ring mounted on the threaded rod.

[0033] This or these stop rings make it possible to prevent the longitudinal translation of the threaded rod in the direction of its axis X'.

[0034] Other axial retention means may be used alternatively. For example, retention by shoulder, by stop screw or by any other similar means may be envisaged.

[0035] Advantageously, a hollow imprint can be provided at one end of the threaded rod.

[0036] This hollow imprint allows a portion of a tool of suitable complementary shape to be engaged therein, in order to connect this tool to the threaded rod. The threaded rod can then be easily rotated by means of this tool.

[0037] Alternatively, protruding reliefs may be provided at the end of the threaded rod in order to facilitate its gripping by means of a tool.

[0038] Advantageously, the angular adjustment assembly may further comprise a device for motorizing the rotation of the threaded rod.

[0039] This motorization device makes it possible to automate the angular adjustment, which is particularly advantageous in the case of an application for an aircraft turbomachine. For this, a servomotor will be used, for example.

[0040] A second aspect of the invention relates to a system for angular adjustment of a crown of blades with adjustable orientation of a turbomachine or turbomachine testing machine, which comprises an angular adjustment assembly as described previously for each of the blades with adjustable orientation.

[0041] Advantageously, such an adjustment system may further comprise a device for synchronizing the rotation of the threaded rods of the angular adjustment assemblies.

[0042] The synchronization device makes it possible to connect all the gears of the different angular adjustment assemblies together so that they are actuated simultaneously and in the same way. The angular position of all the blades of the blade ring can thus be changed synchronously, i.e. simultaneously and in the same way.

[0043] This synchronization device may for example comprise a set of universal joints or a common toothed crown engaging with mating teeth made at one end of the threaded rods.

[0044] A third aspect of the invention relates to an aircraft turbomachine comprising at least one angular adjustment assembly as described previously.

[0045] A fourth aspect of the invention relates to a turbomachine testing machine comprising at least one angular adjustment assembly as described above.

[0046] A fifth aspect of the invention relates to a method for angular adjustment of a variable-pitch blade, carried out by means of an angular adjustment assembly as described previously and in which: • the threaded rod is rotated until the adjustable orientation vane has reached the desired angular position.

[0047] Advantageously, when this method is carried out by means of an angular adjustment assembly comprising a locking screw which, when tightened, bears against the threaded rod, this method may further comprise the following steps: • before rotating the threaded rod, loosen the locking screw until it no longer rests against the threaded rod, and • after rotating the threaded rod, tighten the locking screw until it rests against the threaded rod.

[0048] The invention and its various applications will be better understood upon reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0049] The figures are presented for information purposes only and in no way limit the invention.

[0050] [Fig.l] is a sectional view of a portion of a testing machine according to an example of the invention.

[0051] [Fig.2] is a schematic side view of an exemplary adjustment assembly angular according to the invention.

[0052] [Fig.3] is a cross-section along plane III-III of [Fig.2], seen from above and illustrating the angular adjustment assembly of [Fig.2].

[0053] [Fig.4] is an enlargement of the detail circled in [Fig.3].

[0054] [Fig.5], [Fig.6] and [Fig.7] are partial side views schematically illustrating the successive steps of an example of an adjustment method according to the invention. DETAILED DESCRIPTION

[0055] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0056] In the present application, the terms "upstream" and "downstream" are defined with respect to the normal flow direction of gas (from upstream to downstream) through a turbomachine or a turbomachine testing machine.

[0057] Also referred to as "axis of the turbomachine" or "axis of the test machine", the longitudinal axis of the turbomachine or of the test machine corresponding to the axis of rotation of the rotor of this turbomachine or test machine. This axis is called X in the figures. The axial direction corresponds to the direction of this X axis and a radial direction is a direction perpendicular to the X axis and intersecting this axis. For example, the X' axis has an axial direction and the Y axis a radial direction.

[0058] Unless otherwise specified, the adjectives "interior", "internal", "exterior", "external" are used in the present application with reference to a radial direction, so that the interior part of an element is, in a radial direction, closer to the X axis than the exterior part of the same element.

[0059] Furthermore, the expressions "top", "bottom", "upper", "lower" are defined with respect to the orientation of the parts as shown in the figures. It is obvious that this orientation will not necessarily be retained in use.

[0060] Furthermore, the expressions “variable pitch vane”, “adjustable orientation vane” or “pivoting vane” are synonymous.

[0061] The figures show an example of an angular adjustment assembly 1 according to the invention. This angular adjustment assembly 1 can be installed in a turbomachine or in a turbomachine testing machine 2.

[0062] An example of a test machine 2 has been partially shown in [Fig. 1]. Such a test machine 2 makes it possible to simulate an aircraft turbomachine and to test its components under different aerodynamic conditions in order to study their performance.

[0063] The test machine 2 thus comprises, for example, a fan 3 formed from a ring of moving blades 4, followed downstream by a straightening stator ring 5 comprising adjustable orientation blades 6 of the OGV type (one of which has been framed for greater visibility in [Fig.l]).

[0064] An angular adjustment assembly 1 is advantageously installed for each of these adjustable orientation blades 6. All the angular adjustment assemblies 1 of the crown 5 can advantageously be associated with a synchronization device and together form an angular adjustment system 7 for the crown 5 of adjustable orientation blades 6.

[0065] An example of adjustment assembly 1 has been more specifically represented in Figures 2 to 4.

[0066] The adjustable orientation blade 6 comprises a base 8, mounted in a hub 9, and a body 10 which rises out of the hub 9 from this base 8. This body 10 forms a curved blade 11 which extends in a substantially radial general direction.

[0067] In order to be able to adjust its orientation, the blade 6 is mounted to rotate freely around a radial Y axis, perpendicular and intersecting the X axis. It is thus capable of pivoting around the Y axis, which modifies the angular position of the blade 11 which can consequently adopt any angular position which can be obtained by a rotation from 0 to 360°.

[0068] The base 8 of the blade 6 is engaged in a housing 12 of the hub 9, which is generally cylindrical and open upwards. The diameter of this housing 12 widens in the upper part, thus forming a shoulder 13.

[0069] The base 8 comprises in the upper part a support collar 14 which rests on the shoulder 13 of the housing 12 and thus ensures the longitudinal retention of the blade 6. The support collar 14 also serves as a cover for the housing 12 by closing its upper opening. It thus protects the parts of the device located in the housing 12 from the environment prevailing in the turbomachine or the test machine 2.

[0070] The blade 6 also comprises a toothed wheel 15 with axis Y, located in the lower part of its base 8, under the support collar 14. This toothed wheel 15 is kinematically linked to the blade 6 and therefore also free to rotate around the axis Y.

[0071] In the example shown, this toothed wheel 15 is directly shaped in the lower part of the base 8 of the blade 6 (i.e. made in one piece with it). But, it could also be attached and fixed to it.

[0072] This toothed wheel 15 comprises on its periphery a multitude of teeth 16 which mesh with the threads 17 of a threaded rod 18, oriented along an axis X' parallel to the axis X, to form a gear of the wheel and worm type.

[0073] The threaded rod 18 belongs to an adjustment device 19 which makes it possible to pivot the adjustable orientation blade 6 around the Y axis to adjust its angular position. Indeed, the rotation of the threaded rod 18 around its X' axis causes the toothed wheel 15 to pivot around the Y axis and consequently the pivoting around the Y axis of the blade 6 which is kinematically linked to it.

[0074] The threaded rod 18 is arranged in a housing 20 of the hub 9 which communicates with the housing 12 in which the base 8 of the blade 6 is located in order to allow the threaded rod 18 to cooperate with the toothed wheel 15.

[0075] In the example shown, the housing 20 comprises two lateral parts 21 which communicate with the housing 12 via bores 22 through walls 23 of the hub 9. The threaded rod 18 successively passes through the first lateral part 21, the first bore 22, the housing 12, the second bore 22 and the second lateral part 21 of the housing 20.

[0076] The central part 24 of the threaded rod 18 is therefore located in the housing 12 where its threads 17 are engaged with the teeth 16 of the toothed wheel 15.

[0077] The ends 25 of the threaded rod 18, preferably not threaded, extend into the lateral parts 21 of the housing 20. They are retained there axially by stop rings 26 (also called stop rings or snap rings), placed in circular grooves 27 of the threaded rod 18, which come into abutment against the walls 23 of the hub 9.

[0078] In one of the ends 25 of the threaded rod 18, a hollow shape or imprint 28 has been provided. It has the complementary shape of the end 29 of a tool 30 which can be engaged therein to drive it in rotation along the axis X'. It can thus, for example, have a hollow hexagonal, cruciform, square, slotted or star-shaped shape, complementary to that of a suitable wrench or screwdriver. Depending on the applications, this tool can be manual or automated (by servomotor or other mechanical locking).

[0079] The angular adjustment assembly 1 comprises a locking screw 31, which is mounted in a threaded bore 32 of the hub 9 opening into the housing 20 of the threaded rod 18.

[0080] When the locking screw 31 is tightened, it protrudes into the housing 20 and comes to bear against the threaded rod 18, preferably against an unthreaded part thereof, for example one of its ends 25. It thus prevents the pivoting of the threaded rod 18 around the axis X', which blocks the positioning of the blade 6. The angular adjustment assembly 1 is then locked. To unlock it, it is sufficient to loosen the locking screw 31 so that it is no longer in contact with the threaded rod 18 which frees its pivoting.

[0081] The different steps of an adjustment method carried out using the adjustment assembly 1 described above have been schematically represented in Figures 5 to 7.

[0082] The first step, shown in [Fig.5], consists of unlocking the adjustment assembly 1 by unscrewing the locking screw 31 so that it rises in the bore 32. The translational movement of the screw 31 has been symbolized by the arrow 33. By this movement, the locking screw 31 is no longer in contact with the end 25 of the threaded rod 18 which is released.

[0083] The second step has been shown in [Fig.6] and consists of adjusting the angular positioning of the blade 6. For this, the end 29 of a tool 30 is engaged in the imprint 28 at the end 25 of the threaded rod 18 which is now free to rotate. By rotating this tool 30 according to the arrow 34, the rotation of the threaded rod 18 around its axis X' which is symbolized by the arrow 35 is caused.

[0084] The threads 17 of the threaded rod 18 being engaged with the teeth 16 of the toothed wheel 15, this rotation of the threaded rod 18 causes that of the toothed wheel 15 around its axis Y and consequently that of the blade 6 which is kinematically linked to it. The rotation of the blade 6 along the Y axis has been symbolized by the arrow 36.

[0085] When the blade 6 has reached the desired angular position, the tool 30 is stopped from operating to stop the rotation of the threaded rod 18.

[0086] The last step, shown in [Fig.7], consists of locking the adjustment assembly 1 again to block the blade 6 in the desired angular position which was obtained in the previous step. To do this, it is sufficient to screw the locking screw 31 to lower it into the bore 32, as shown by the arrow 37. The locking screw 31 ends up coming into abutment against the end 25 of the threaded rod 18 and its tightening blocks the rotation of the threaded rod 18. The adjustment assembly 1 is then locked.

Claims

Claims

1. Angular adjustment assembly (1) for an adjustable orientation blade (6) of a turbomachine or of a testing machine (2) of an X-axis turbomachine, said angular adjustment assembly comprising: - an adjustable orientation blade (6), comprising a base (8) and a body (10) extending radially from this base, the adjustable orientation blade (6) being free to pivot about a Y axis perpendicular to and intersecting the X axis; and - a device (19) for adjusting the pivoting of the adjustable orientation blade (6) around the Y axis, - characterized in that the adjustable orientation blade (6) comprises at its base (8) a toothed wheel (15) with axis Y, free to pivot around the Y axis and kinematically connected to the adjustable orientation blade (6), and - in that the adjustment device comprises a threaded rod (18) with axis X' parallel to the X axis which is engaged with the toothed wheel (15).

2. Angular adjustment assembly (1) according to claim 1, characterized in that it further comprises a locking screw (31) which, when tightened, bears against the threaded rod (18).

3. Angular adjustment assembly (1) according to one of the preceding claims, characterized in that the toothed wheel (15) is in one piece with the base (8) of the adjustable orientation blade (6).

4. Angular adjustment assembly (1) according to one of the preceding claims, characterized in that it further comprises a device for motorizing the rotation of the threaded rod (18).

5. Angular adjustment system (7) for a crown (5) of adjustable orientation blades (6) of a turbomachine or turbomachine testing machine (2), characterized in that it comprises an angular adjustment assembly (1) according to one of claims 1 to 4 for each of the adjustable orientation blades (6).

6. Angular adjustment system (7) according to claim 5 characterized in that it further comprises a device for synchronizing the rotation of the threaded rods (18) of the angular adjustment assemblies (1).

7. Aircraft turbomachine comprising at least one angular adjustment assembly (1) according to one of claims 1 to 4.

8. Turbomachine testing machine (2) comprising at least one angular adjustment assembly (1) according to one of claims 1 to A

9. Method for angular adjustment of a variable-pitch blade (6) characterized in that it is carried out by means of an angular adjustment assembly (1) according to one of claims 1 to 4 and in which: - the threaded rod (18) is rotated until the adjustable-orientation blade (6) has reached the desired angular positioning.

10. Angular adjustment method according to claim 9 characterized in that it is carried out by means of an angular adjustment assembly (1) according to claim 2 or one of claims 3 to 4 in that they depend on claim 2 and in that: - before rotating the threaded rod (18), the locking screw (31) is loosened until it no longer bears against the threaded rod (18), and - after rotating the threaded rod (18), the locking screw (31) is tightened until it bears against the threaded rod (18).

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