BALANCE WEIGHT FOR AN AIRCRAFT TURBOMACHINE ROTOR

Abstract

A balancing weight (30) for an aircraft turbomachine rotor, the balancing weight (30) being able to be removably attached to an aircraft turbomachine rotor, characterized in that the balancing weight (30) has a generally elongated shape along an elongation axis (Y) and comprises two hooks (32, 34) at its two longitudinal ends, respectively, these two hooks (32, 34) being axially oriented towards each other and being movable in axial translation along the elongation axis (Y) so as to be able to be brought closer together to clamp a rotor element between them, and to be moved apart to remove the weight (30) from this element. Figure for the abstract: Figure 3

Description

Title of the invention: Balancing weight for an aircraft turbomachine rotor Technical field of the invention

[0001] The present invention relates in particular to a balancing weight for an aircraft turbomachine rotor, as well as a method for mounting this weight. Technical background

[0002] An aircraft turbomachine includes rotors which must be rotationally balanced to avoid or reduce in particular an imbalance.

[0003] This is, for example, the case of a turbine rotor. A turbine rotor comprises a series of axial stages (along the axis of gas flow) arranged one behind the other. Each stage includes a rotor wheel with blades and a stator vane distributor. The wheel is rotated opposite the corresponding distributor.

[0004] In the present application, upstream and downstream are defined with respect to the normal flow direction of the air streams (from upstream to downstream) through the turbomachine. The "turbomachine axis" is the axis of rotation of the turbomachine's main rotor. The axial direction corresponds to the direction of the turbomachine axis, and a radial direction is a direction perpendicular to and intersecting the turbomachine axis. Similarly, an axial plane is a plane containing the turbomachine axis, and a radial plane is a plane perpendicular to this axis. The adjectives "inner" or "internal" and "outer" or "external" are used with reference to a radial direction such that the inner part of an element is, along a radial direction, closer to the turbomachine axis than the outer part of the same element.The stacking axis of a blade is the axis perpendicular to the axis of the turbomachine, passing through the center of gravity of the innermost section of the blade (i.e., the section closest to the axis of the turbomachine). Typically, a turbomachine blade comprises a blade extending along the stacking axis of the blade, between the radially inner and outer ends of the blade.

[0005] A wheel classically comprises an annular disk centered on the axis of rotation and on which a plurality of blades are fixed.

[0006] An example of a blade is shown in [Fig. 1]. A blade of this type is described in patent document FR-A1-3 079 847. This blade 10 comprises a blade 16 extending along the stacking axis X of the blade, between the radially inner end 10a and outer end 10b of the blade 10. At its inner end 10a, the blade 10 comprises a lower platform 19 and a foot 12 by which it is fixed to a disk (not shown in [Fig.1]).

[0007] At its outer end 10b, the blade 10 has a flange 14. The flange 14 comprises a platform 20 externally delimiting the gas flow path between the blades 16, and having opposing lateral edges 21, 22. The platform 20 has an upstream portion 24 called the "upstream flange" and a downstream portion 28 called the "downstream flange". The flange 14 also includes upstream sealing flaps 31 and downstream flaps 32 extending radially outwards from the outer face of the platform 20. Each of the lateral edges 21, 22 of the platform has, between the upstream flaps 31 and downstream flaps 32, a substantially "U"-shaped profile. In the case of other blades, this profile may take the form of a "Z" or a "V", for example.

[0008] Balancing a rotor or rotor element generally involves removing or adding material to the rotor or rotor element in order to correct its dynamic rotational behavior. Adding material is easier, and a simple method is to mount one or more balancing weights on the rotor or rotor element.

[0009] For example, there are balancing weights that are fixed to the mounting flanges of the rotor wheels. In practice, such a weight includes an opening for one of the flange mounting screws. This type of weight can be removed but is generally permanently fixed to the rotor or rotor element since removal is rare and unnecessary.

[0010] In some cases, balancing weights may be temporarily mounted on a rotor or rotor element, for example, to perform tests such as certification tests. These tests may consist of reducing an imbalance or, conversely, creating an imbalance. These weights are attached to a rotor or rotor element in a more confined and difficult-to-access environment. Furthermore, the available mounting areas for these balancing weights are limited and not particularly suitable, which may lead to displacement or vibration of the weights, or even accidental removal of the weights.

[0011] There is therefore a need for a balancing weight that can resolve all or part of the problems and drawbacks of the prior art. Summary of the invention

[0012] The invention thus provides a balancing weight for an aircraft turbomachine rotor, the balancing weight being able to be removably fixed to an aircraft turbomachine rotor, characterized in that the balancing weight has a generally elongated shape along an axis of elongation and comprises two hooks respectively at its two longitudinal ends, these two hooks being axially oriented towards each other and being mobile in axial translation along the axis of extension so as to be able to be brought closer together to clamp between them an element of the rotor, and to be moved away from each other to dismantle the weight of this element.

[0013] The weight is designed to facilitate its mounting in and on a rotor, as well as its removal. This allows the weight to be used for balancing a rotor, temporarily if necessary. The weight is configured to be hooked onto the rotor or rotor element and comprises two facing hooks or claws designed to grip a portion of the rotor or rotor element. The design and use of the weight according to the invention are therefore relatively simple.

[0014] The weight according to the invention may comprise one or more of the following features, taken individually or in combination with each other: • the weight comprises a central body, each of the hooks being connected to the central body so as to be movable in axial translation along the axis of extension relative to this body; the central body can be configured to have a predetermined balancing mass; naturally, it is the total mass of the weight, and not just of the central body, which is taken into account for the balancing of a rotor; • each of the hooks is connected to the body by a sliding or sliding connection; • the weight also includes at least one elastic element which forces the axial approach of the hooks; • each of the hooks has a bearing surface on the aforementioned element, this bearing surface being inclined with respect to said axis of elongation; • the support surfaces of the hooks are parallel; • The weight is made of a carbon or graphite-based material; this reduces the risk of wear on the material of the rotor element on which the weight is mounted, because the material of the weight is relatively fragile and brittle and will deteriorate more quickly than that of the rotor element, which is generally metallic, for example by friction.

[0015] The present invention also relates to an assembly comprising a rotor blade for an aircraft turbomachine, and a counterweight as described above.

[0016] The blade may comprise a blade, one end of which is connected to a foot and the opposite end of which is connected to a platform, this platform comprising two opposite edges which are located respectively on the side of a leading edge and a trailing edge of the blade, the platform further comprising an internal surface located on the side of the blade,

[0017] Preferably, the weight is pressed against the inner surface and its hooks bear respectively on the two opposite edges of the platform.

[0018] The weight is preferably located on the extrados side of the blade.

[0019] The weight preferably has its elongation axis parallel to a chord of the blade.

[0020] The present invention also relates to a rotor for an aircraft turbomachine, comprising a rotor disc and several assemblies as described above, the feet of the blades of the assemblies being mounted in recesses in the outer periphery of the rotor disc.

[0021] The present invention further relates to a method of mounting a counterweight as described above, on a rotor element such as a rotor blade, this method comprising the following steps:

[0022] a) mounting the weight to the end of a tool adapted for mounting the weight, this tool having a distal end for gripping the weight, and a proximal end for manipulating the tool, the proximal end of the tool having an actuator, and the distal end of the tool having a mechanism which is connected to the actuator and which allows the hooks to be brought closer together or further apart by acting on the actuator,

[0023] b) position the weight at the level of the rotor element using the tool, and

[0024] c) control the bringing together of the hooks by means of the actuator so that that the hooks grip the rotor element.

[0025] The method according to the invention may comprise one or more of the following features or steps, taken individually or in combination with each other:

[0026] - the rotor element is a rotor blade, step b) consisting of positioning the weight on an internal surface of a blade platform, and step c) of controlling the approach of the hooks so that they bear respectively on two opposite edges of the blade platform located respectively on the side of a leading edge and a trailing edge of a blade;

[0027] - steps b) and c) are carried out on a rotor having several rotor blades mounted on the outer periphery of a rotor disk, or in a rotor module comprising several such rotors that are rotationally fixed to one another. Brief description of the figures

[0028] The invention will be better understood and other details, features and advantages of the invention will become more apparent upon reading the following description, given by way of non-limiting example and with reference to the accompanying drawings in which:

[0029] [Fig. 1] [Fig. 1] is a schematic perspective view of a rotor blade,

[0030] [Fig.2] [Fig.2] is a partial schematic cross-sectional view of a tur- module bomachine, and in particular a turbine,

[0031] [Fig.3] [Fig.3] is a schematic view of the platform of a rotor blade, on which a balancing weight according to the invention is mounted,

[0032] [Fig.4] [Fig.4] is a schematic perspective view of the balancing weight of [Fig.3],

[0033] [Fig.5] [Fig.5] is another schematic side view of the balancing weight of [Fig.3],

[0034] [Fig. 6] [Fig. 6] is a schematic perspective view of the balancing weight of [Fig. 3], and of a tool for mounting this weight, and illustrates a method for mounting the weight, and

[0035] [Fig.7] [Fig.7] is a partial schematic perspective view of the balancing weight of [Fig.3]. Detailed description of the invention

[0036] The [Fig.1] has been described in the preceding.

[0037] Figures 2 to 5 illustrate a first embodiment of a balancing weight 30 for an aircraft turbomachine rotor.

[0038] The weight 30 is shown alone in figures 4 and 5 and is shown mounted on a rotor in figures 2 and 3.

[0039] In the example shown, which is not limiting, the rotor is a rotor blade 10 or a rotor comprising such a rotor blade 10 or a turbomachine module, such as a turbine, comprising such a rotor blade 10.

[0040] The rotor blade 10 is of the type illustrated in [Fig.1] and comprises a blade 16 extending along the stacking axis X of the blade, between the radially internal 10a and external 10b ends of the blade 10. At its internal end 10a, the blade 10 comprises a lower platform 19 and a foot 12 by which it is fixed to a disk 13.

[0041] The disc 13 comprises at its periphery alveoli 15 oriented substantially parallel to the axis of the disc 13 and arranged alternately with teeth 17 of the disc 13. Each blade 10 is held to the disc 13 by insertion of the foot 12 into one of the alveoli 15 of the disc 13. The foot 12 is held radially by cooperation of form by the teeth 17 of the disc 13.

[0042] At its outer end 10b, the blade 10 has a heel 14.

[0043] The heel 14 comprises a platform 20 externally delimiting the gas flow path circulating between the blades 16, and having opposing lateral edges 21, 22 ([Fig. 3]). The platform 20 has an upstream portion 24 called a "spoiler". upstream" and comprising an upstream edge 24a and a downstream part 28 called "downstream spur" and comprising a downstream edge 28a.

[0044] The upstream edge 24a is located on the side of the leading edge 16a of the blade 16, and the downstream edge 28a is located on the side of the trailing edge 16b of the blade 16. As can be seen in [Fig.2], the blade 16 has a chord C (which is a virtual line which connects its leading edge 16a to its trailing edge 16b in a straight line) which is inclined with respect to the upstream edges 24a and downstream edges 28a.

[0045] The heel 14 also includes upstream sealing strips 31 and downstream 32 extending radially outwards from the outer surface 20b of the platform 20 ([Fig.2]). Each of the lateral edges 21, 22 of the platform has, in particular between the upstream strips 31 and downstream strips 32, a profile substantially in the shape of a “U”, “Z” or “V” for example.

[0046] The weight 30 is suitable for being removably fixed on a rotor and in particular on the platform 20 of the rotor blade 10.

[0047] The weight 30 has a general elongated shape along an elongation axis Y and includes two hooks 32, 34 respectively at its two longitudinal ends.

[0048] The two hooks 32, 34 are axially oriented towards each other and are movable in axial translation along the elongation axis Y so that they can be brought closer together to clamp between them an element of the rotor such as the platform 20, and moved away from each other to dismantle the weight 30 from this element.

[0049] In the example shown in figures 1 and 2, we see that the weight 30 is mounted on the inner or internal surface 20a of the platform 20 which is located on the side of the blade 16, and therefore on the opposite side to the blades 31, 32.

[0050] The weight 30 can be radially pressed against this internal surface 20a.

[0051] The hooks 32, 34 of the weight 30 bear respectively on the two opposite edges 24a, 28a of the platform 30.

[0052] Each of the hooks 32, 34 may have a general L or U shape and may include a hooking rim 35 oriented towards the other hook and intended for example to bear against the external surface 20b of the platform 20 located on the side of the slats 31, 32.

[0053] The weight 30 can be mounted on the side of an extrados of the blade 16, as illustrated in [Fig.3].

[0054] The weight 30 can have its elongation axis Y which is parallel to the chord C of the blade 16 and which is therefore inclined with respect to the aforementioned edges 24a, 28a as seen in [Fig.3].

[0055] As can be more clearly seen in Figures 4 and 5, the weight 30 may comprise a central body 36, each of the hooks 32, 34 being connected to the central body 36 so as to be movable in axial translation along the elongation axis Y with respect to this 36-point body.

[0056] Each of the hooks 32, 34 can be connected to the body 36 by a sliding or sliding linkage system 38.

[0057] The weight 30 may further include at least one elastic element 40 which forces the axial approach of the hooks 36.

[0058] Each of the hooks 32, 34 can have a bearing surface 32a, 34a which is inclined or perpendicular with respect to the elongation axis Y. These bearing surfaces 32a, 34a of the hooks 32, 34 can be parallel to each other.

[0059] The weight 30 is preferably made of a carbon or graphite-based material.

[0060] Figures 6 and 7 illustrate a method of mounting the balancing weight 30 described above.

[0061] The assembly process comprises the following steps:

[0062] a) mount the weight 30 to the end of a tool 50,

[0063] b) position the weight 30 at the level of the rotor element using the tool 50, and

[0064] c) control the approach of the hooks 32, 34 so that the hooks 32, 34 clamp the rotor element.

[0065] The tool 50 is specifically adapted for mounting the weight 30 according to the invention. This tool 50 has a distal end 50a for gripping the weight 30, and a proximal end 50b for manipulating the tool.

[0066] The proximal end 50a of the tool 50 includes an actuator 52 such as a lever, a trigger or the like.

[0067] The distal end 50b of the tool 50 includes a mechanism 54 which is connected to the actuator 52 and which allows the approach or separation of the hooks 32, 34 from each other to be controlled by acting on the actuator 52. The actuator 52 is connected to the mechanism 54 by a linkage or similar.

[0068] As can be seen in Figures 6 and 7, the weight 30 may include a housing 42 in which the distal end 50a of the tool 50 is intended to be engaged, and in which the sliding or sliding linkage system 38 is accessible. The mechanism 54 of the tool 50 is configured to apply a force to this system 38 and to move the hooks 32, 34 away from or towards each other, depending on the action performed by an operator on the actuator 52.

[0069] Step c) is thus carried out by means of the actuator 52. An operator who manipulates the tool 50 acts on this actuator 52 to cause, by means of the mechanism 54, a bringing together or a moving apart of the hooks 32, 34. In the aforementioned case where the hooks are axially forced towards each other, the actuation of the tool 50 can be used to move the hooks 32, 34 apart.

[0070] When the rotor element is a rotor blade 10 as described above, step b) consists of positioning the weight 30 on the internal surface 20a of the platform 20 of the blade 10, and step c) consists of controlling the approach of the hooks 32, 34 so that they bear respectively on the two opposite edges 24a, 28a of the platform 20 of the blade 10.

[0071] Steps b) and c) can be carried out on a rotor comprising several rotor blades 10 mounted on the outer periphery of a rotor disk 13, or in a rotor module comprising several rotors of this type which are rotationally fixed to each other.

[0072] In the case where several weights 30 are used to balance a rotor, these weights 30 may be identical and therefore have identical masses, or they may, on the contrary, differ from one another in their masses. Advantageously, the masses of the weights 30 may vary according to the shape and dimensions of their central bodies 36. For example, the central bodies 36 of the weights 30 may be thicker or thinner to vary the masses of the weights 30. In the absence of central bodies 36, the hooks 30, 32 of the weights could be thickened in certain places, for example, to vary the masses of the weights 30.

Claims

Demands

1. Balancing weight (30) for an aircraft turbomachine rotor, the balancing weight (30) being able to be removably fixed on an aircraft turbomachine rotor, characterized in that the balancing weight (30) has a generally elongated shape along an axis of elongation (Y) and comprises two hooks (32, 34) respectively at its two longitudinal ends, these two hooks (32, 34) being axially oriented towards each other and being movable in axial translation along the axis of elongation (Y) so as to be able to be brought together to clamp an element of the rotor, and to be moved apart to remove the weight (30) from this element.

2. Weight (30) according to claim 1, wherein it comprises a central body (36), each of the hooks (32, 34) being connected to the central body (36) so as to be movable in axial translation along the elongation axis (Y) with respect to this body (36).

3. Weight (30) according to claim 2, wherein each of the hooks (32, 34) is connected to the body by a sliding or sliding link (38).

4. Weight (30) according to any one of the preceding claims, wherein it further comprises at least one elastic element (40) which induces axial rapprochement of the hooks (32, 34).

5. Weight (30) according to any one of the preceding claims, wherein each of the hooks (32, 34) has a bearing surface (32a, 34a) on the aforementioned element, this bearing surface (32a, 34a) being inclined with respect to said elongation axis (Y).

6. Weight (30) according to the preceding claim, wherein the bearing surfaces (32a, 34a) of the hooks (32, 34) are parallel.

7. Weight (30) according to any one of the preceding claims, wherein it is made of a carbon-based or graphite-based material.

8. An assembly comprising a rotor blade (10) for an aircraft turbomachine, and a counterweight (30) according to any one of the preceding claims, the blade (10) comprising a blade (16) having one end connected to a foot (12) and an opposite end connected to a platform (20), this platform (20) having two opposite edges (24a, 28a) which are located respectively on the side of a leading edge (16a) and a trailing edge leakage (16b) of the blade (16), the platform (20) further comprising an internal surface (20a) located on the side of the blade (16), the weight (30) being pressed against the internal surface (20a) and its hooks (32, 34) bearing respectively on the two opposite edges (24a, 28a) of the platform (20).

9. Assembly according to claim 7, wherein the weight (30) is located on the side of an extrados of the blade (16).

10. Assembly according to claim 7 or 8, wherein the weight (30) has its elongation axis (Y) which is parallel to a chord (C) of the blade (16).

11. Rotor for an aircraft turbomachine, comprising a rotor disc (13) and several assemblies according to any one of claims 7 to 9, the feet (12) of the blades (10) of the assemblies being mounted in recesses (15) of the outer periphery of the rotor disc (13).

12. A method for mounting a counterweight (30) according to any one of claims 1 to 6 on a rotor element such as a rotor blade (10), said method comprising the following steps: a) mounting the counterweight (30) to the end of a tool (50) adapted for mounting the counterweight (30), this tool having a distal end (50a) for gripping the counterweight (30), and a proximal end (50b) for manipulating the tool (50), the proximal end (50b) of the tool (50) having an actuator (52), and the distal end (50a) of the tool (50) having a mechanism (54) which is connected to the actuator (52) and which allows the hooks (32, 34) to be brought closer together or further apart by acting on the actuator (52), b) positioning the counterweight (30) at the rotor element by means of the tool (50), and (c) control the coming together of the hooks (32, 34) by means of the actuator (52) so that the hooks (32,34) enclose the rotor element.

13. A method according to claim 12, wherein the rotor element is a rotor blade (10), step b) of positioning the counterweight (30) on an internal surface (20a) of a platform (20) of the blade (10), and step c) of controlling the movement of the hooks (32, 34) so ​​that they bear respectively on two opposite edges (24a, 28a) of the platform (20) of the blade (10) located respectively on the side of a leading edge (16a) and a trailing edge (16b) of a blade (16) of dawn (10).

14. A method according to claim 12 or 13, wherein steps b) and c) are carried out on a rotor comprising several rotor blades (10) mounted on the outer periphery of a rotor disk (12), or in a rotor module comprising several such rotors which are rotationally fixed to one another.

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