Retaining ring for axial locking of turbine blades

Abstract

Retaining ring for axial locking of blades of a turbine Retaining ring (9) for axial locking of blades of a turbine comprising an upstream turn (15) and a downstream turn (17) which are joined and stacked axially relative to the general axis (X) in a flow direction; a connecting tab (19) connecting the upstream turn (15) and the downstream turn (17) so that the upstream turn (15), the downstream turn (17) and the connecting tab (19) constitute a profiled winding with two contiguous turns; one or more recesses (27) of material formed in the downstream turn (17) and / or the upstream turn (15) located opposite the connecting tab (19) or located at several symmetrically located locations around an alignment plane (29) defined by the general axis (X) and a diameter of the retaining ring (9) passing through the connecting tab (19). Figure 3

Description

Title of the invention: Retaining ring for axial locking of turbine blades Field of invention

[0001] The present invention relates to a retaining ring suitable for axially locking blades of a turbine. The retaining ring is particularly suitable for a turbine belonging to the rotor of a turbomachine. Prior art

[0002] It is known to have a rotary turbine comprising a disk and blades attached to the contour of the disk. In particular, such a turbine is suitable as a low pressure or high pressure turbine for an aircraft gas turbomachine.

[0003] The low pressure turbine or the high pressure turbine rotates around the general axis of rotation of the turbomachine in operation. This rotation induces a certain number of mechanical constraints on the blades.

[0004] The axial retention of the blades along the general axis relative to the disc is an important subject. It can be achieved by a retaining ring cooperating with the blades and the disc so as to block their relative axial movements.

[0005] The retaining ring has a generally circular shape and is centered relative to the general axis when it cooperates with the blades and the disk. The retaining ring may have a constant profiled section, for example rectangular with rounded corners. This arrangement allows good balancing and limits the unbalance of the rotating turbine.

[0006] However, the retaining ring must have a radially slanted cutout for its assembly, i.e. a cutout having an angle relative to a direction radial to the general axis.

[0007] This slanted cut creates an imbalance during the rotation of the turbine which is significant in relation to the mass of the turbine. This generates significant vibrations of the turbomachine during operation, as well as misalignment of the rotor sealing elements.

[0008] The present invention aims to resolve all or part of the drawbacks mentioned above. Statement of the invention

[0009] To this end, the present invention relates to a retaining ring for axially locking blades of a turbine, the retaining ring extending around a general axis of rotation and capable of cooperating with the blades and a disk of the turbine in a retaining position so as to block axial movement of the blades relative to the disk, the retaining ring comprising:

[0010] an upstream turn and a downstream turn which are joined and stacked axially relative to the general axis in a flow direction,

[0011] a connecting tab connecting the upstream turn and the downstream turn so that the upstream turn, the downstream turn and the connecting tab constitute a profiled winding with two contiguous turns,

[0012] one or more material recesses provided in the downstream turn and / or the upstream turn located opposite the connecting tab or located at several symmetrically located locations around an alignment plane defined by the general axis and a diameter of the retaining ring passing through the connecting tab.

[0013] In other words, the connecting space is diametrically opposite the recess or the plurality of recesses which are regularly distributed. The retaining ring in the retaining position has a general shape extending along a transverse circle and in particular perpendicular to the general axis.

[0014] The recess(es) extend symmetrically with respect to a plane passing through a ray orthogonal to the general axis.

[0015] This spatial configuration of the retaining ring is advantageous because the lack of material at the level of the connecting space is compensated radially by the recess(es).

[0016] When the turbine is rotating, the lack of material at the connecting space does not cause an imbalance.

[0017] According to one aspect of the invention, the profiled winding with two contiguous turns extends between a first end of the upstream turn and a second end of the downstream turn, the first end being distant from the second end along the circumference and the connecting tab extending into a connecting space between the first end and the second end along the circumference.

[0018] The alignment plane passes midway between the first end and the second end.

[0019] According to one aspect of the invention, the retaining ring has a center of gravity located at the center of a circle defining a general shape of the retaining ring, said center being located on the general axis when the retaining ring is in the retaining position.

[0020] The general shape extending in a circle and the particular material distribution of the retaining ring allow it not to create an imbalance during rotation of the turbine.

[0021] It should be noted that a significant imbalance causes vibrations of the turbine and of the turbomachine comprising the turbine, as well as misalignment of the sealing elements of the rotor of the turbomachine (moving ring wipers, moving blades and labyrinth rings). The retaining ring is therefore particularly advantageous.

[0022] According to one aspect of the invention, the recess(es) are blind holes.

[0023] This arrangement has the advantage of not allowing the passage of fluid, which could disrupt the proper functioning of the turbomachine.

[0024] According to an alternative, the recess(es) are through holes.

[0025] According to one aspect of the invention, the blind hole(s) extend axially from the outside of the retaining ring towards a contact surface between the upstream turn and the downstream turn.

[0026] The blind holes do not create a through opening axially and do not create one transversely to the general axis.

[0027] According to one aspect of the invention, the recess(es) each have an oblong contour extending along the circumference of the retaining ring.

[0028] Each recess is therefore surrounded by two uprights of the downstream turn and / or the upstream turn along the circumference. Preferably, the number of recesses is between 1 and 5.

[0029] According to one aspect of the invention, the blind hole(s) have an axial depth corresponding to an axial dimension of the upstream turn or the downstream turn or to a smaller dimension.

[0030] When the axial depth corresponds to the axial dimension of the upstream turn or the downstream turn, the downstream turn is provided with a through hole and this hole is blind when the upstream turn and the downstream turn are mounted in a contiguous manner.

[0031] When the axial depth is of a smaller dimension, preferably one third of the axial dimension of the entire retaining ring, a blind hole is made in the downstream turn.

[0032] According to one aspect of the invention, a circumferential dimension, i.e. along the circumference of the retaining ring, of each blind hole is between one third of the radial dimension of the retaining ring and three times the radial dimension of the retaining ring.

[0033] Optimal mechanical resistance properties were obtained for these blind hole dimensions.

[0034] According to one aspect of the invention, the connecting tab extends in the extension of the upstream turn and also of the downstream turn so that the profiled winding of the retaining ring has a substantially constant section along the upstream turn, the connecting tab and the downstream turn.

[0035] Preferably, said section is constant. The profiled winding may be made from a shaped straight bar. The recesses may be previously made by drilling or other type of material removal prior to shaping.

[0036] The material constituting the retaining ring may be DMD0426 or any other type of material with similar properties.

[0037] According to one aspect of the invention, the connecting tab extends along the circumference and is axially oriented at an angle to pass from the axial position of the upstream turn to the axial position of the downstream turn.

[0038] According to one aspect of the invention, the axial size of the retaining ring is between 4 and 8 times smaller than the radial size of the retaining ring.

[0039] According to one example, the axial size may be between 1 mm and 4 mm, and the radial size may be between 4 mm and 30 mm depending on the functional needs.

[0040] Favorably, an axial size between 3 and 4 mm is used in particular for a gas turbomachine for aircraft.

[0041] The present invention also relates to a turbine for an aircraft gas turbomachine, the turbine comprising:

[0042] the disk adapted to be mounted free to rotate along the general axis on a shaft of the turbomachine,

[0043] the blades regularly distributed circumferentially on the disc, each blade comprising a blade-forming part and a root-forming part by which the blade can be engaged in a corresponding receiving location of the disc,

[0044] a retaining ring as described above configured to cooperate with the disc and the root portions of the blades so as to block axial movement of the blades relative to the disc.

[0045] According to one aspect of the invention, the turbine has, for each blade, a cavity formed in the root portion of said blade and / or in the disc to receive by complementary shape the retaining ring, the cavity extending radially.

[0046] This arrangement allows the retaining ring to be correctly installed so that it is orthogonal to the general axis and prevents any movement of the blades relative to the disc.

[0047] Preferably, for each blade, the cavity comprises a first part formed in the blade and a second complementary part formed in the disc. The installation of the retaining ring makes it possible to radially align and maintain the radial alignment of these two parts.

[0048] This assembly is advantageous because each blade is mounted and can only move axially relative to the disc. This radial position of the retaining ring thus allows effective locking.

[0049] According to one aspect of the invention, the turbine comprises two retaining rings and has two corresponding cavities, the cavities being axially aligned and surrounding the root portion of said blade.

[0050] Using two retaining rings per blade is advantageous for maintaining blades. This involves a reduction in the misalignment of other parts of the turbomachine and contributes to the sealing of the assemblies.

[0051] The present invention further relates to a gas turbomachine for aircraft comprising at least one turbine as described above mounted to rotate, the turbine being a high pressure turbine or a low pressure turbine.

[0052] According to one aspect of the invention, the turbomachine comprises a plurality of turbines mounted to be mobile in rotation and aligned axially, the turbomachine further comprising flanges axially connecting the disks of two successive turbines except the disks of the first and last turbine of the alignment so as to constitute a rotating assembly.

[0053] In other words, two axially successive discs are connected by an upstream flange and a downstream flange, except for the discs of the first and last stages.

[0054] The different aspects defined above which are not incompatible can be combined. Brief description of the figures

[0055] The invention will be better understood with the aid of the detailed description which is set out below with reference to the attached drawings.

[0056] [Fig. 1] is an axial sectional view of a portion of an aircraft gas turbine engine.

[0057] [Fig.2] is a sectional view of a detail of the turbomachine comprising two low pressure turbines and an intercalated rectifier.

[0058] [Fig.3] is a schematic view of a retaining ring of a low pressure turbine.

[0059] [Fig.4] is a schematic top view of a detail of the retaining ring including recesses.

[0060] [Fig.5] is a schematic front view in transparency of a detail of the retaining ring including the recesses. Description with reference to the figures

[0061] In the detailed description which follows of the figures defined above, the same elements or the elements fulfilling identical functions may retain the same references so as to simplify the understanding of the invention.

[0062] In [Fig.l] a double-spool aircraft gas turbomachine 1 is shown. A fluid flow F circulates from upstream to downstream during operation.

[0063] The turbomachine 1 comprises a high pressure turbine 2 and several low pressure turbines 3 downstream of a distributor 4 of the turbomachine 1 itself arranged downstream of the high pressure turbine stage 2.

[0064] The low pressure turbines 3 constitute a bolted assembly which is rotatable. Rectifiers 5 of the turbomachine 1 are axially interposed between two successive low pressure turbines 3.

[0065] In the following text, a turbine 7 is a generic term designating a turbine which can be a high pressure turbine 2 or a low pressure turbine 3.

[0066] As illustrated in [Fig.2], the turbine 7 comprises a retaining ring 9 intended for the axial locking of blades 11 of the turbine 7.

[0067] The retaining ring 9 extends around a general axis X of rotation of the turbine 7 and cooperates with the blades 11 and a disc 13 of the turbine 7 in a retaining position so as to block an axial movement of the blades 11 relative to the disc 13.

[0068] As illustrated in Figures 3 to 5, the retaining ring 9 comprises an upstream turn 15 and a downstream turn 17 which are joined and stacked axially relative to the general axis X in a direction of flow of the turbine 7 in operation.

[0069] The retaining ring 9 comprises a connecting tab 19 connecting the upstream turn 15 and the downstream turn 17 so that the upstream turn 15, the downstream turn 17 and the connecting tab 19 constitute a profiled winding with two contiguous turns between a first end 21 of the upstream turn 15 and a second end 23 of the downstream turn 17.

[0070] The first end 21 is spaced from the second end 23 along the circumference and the connecting tab 19 extends into a connecting space 25 between the first end 21 and the second end 23 along the circumference.

[0071] The retaining ring 9 comprises one or more recesses 27 of material provided in the downstream turn 17 and / or the upstream turn 15 located opposite the connecting tab 19 or located at several symmetrically located locations around an alignment plane defined by the general axis X and a diameter of the retaining ring 9 passing through the connecting tab 19.

[0072] In other words, the connecting space 25 is diametrically opposite the recess 27 or the plurality of recesses 27 which are regularly distributed. The retaining ring 9 in the retaining position has a general shape extending along a transverse circle and in particular perpendicular to the general axis X.

[0073] The lack of material at the level of the connecting space 25 is compensated radially by the recess(es) 27.

[0074] The term "axial" is understood to mean that which extends along the general axis X and the term "radial" is understood to mean that which extends along the axis Z which is transverse to the general axis X and corresponds to the radius of the turbine 7. Along the circumference or circumferentially defines a dimension which follows the curvature of the turbine 7 or of the retaining ring 9.

[0075] The retaining ring 9 has a center of gravity located at the center of a circle defining a general shape of the retaining ring, said center being located on the general axis X when the retaining ring 9 is in the retaining position.

[0076] The recess(es) 27 are blind holes. The retaining ring 9 therefore does not have a through opening generated by the recesses 27.

[0077] The blind hole(s) extend axially from the outside of the ring of retainer 9 towards a contact surface between the upstream turn 15 and the downstream turn 17.

[0078] The blind holes do not generate a through opening axially and do not generate one transversely to the general axis X.

[0079] As illustrated in Figures 4 and 5, the recess(es) 27 each have an oblong contour extending along the circumference of the retaining ring 9.

[0080] Each recess 27 is therefore surrounded by two uprights 31 of the downstream turn 17 and / or of the upstream turn 15 along the circumference. Preferably, the number of recesses is between 1 and 5.

[0081] The blind hole(s) have an axial depth corresponding to an axial dimension of the downstream turn 17 as in [Fig.3] or to a smaller dimension as in [Fig.5].

[0082] When the axial depth corresponds to the axial dimension of the downstream turn 17, the downstream turn 17 is provided with a through hole and this hole is blind when the upstream turn 15 and the downstream turn 17 are mounted in a contiguous manner as is the case in [Fig.3].

[0083] When the axial depth is of a smaller dimension as in [Fig.5], preferably one third of the axial dimension of the entire retaining ring 9, a blind hole is made in the downstream turn 17.

[0084] A circumferential dimension 33, i.e. along the circumference of the retaining ring 9, of each blind hole is between one third of the radial dimension of the retaining ring 9 and three times the radial dimension of the retaining ring 9.

[0085] The connecting tab 19 extends in the extension of the upstream turn 15 and also of the downstream turn 17 so that the profiled winding of the retaining ring has a substantially constant section along the upstream turn 15, the connecting tab 19 and the downstream turn 17.

[0086] Preferably, said section is constant. The profiled winding may be made from a shaped straight bar. The recesses 27 may be previously made by drilling or other type of material removal prior to shaping.

[0087] The material constituting the retaining ring may be DMD0426 or any other type of material with similar properties.

[0088] The connecting tab 19 extends along the circumference and is axially oriented at an angle to move from the axial position of the upstream turn 15 to the axial position of the downstream turn 17.

[0089] The axial size of the retaining ring 9 is between 4 and 8 times smaller than the radial size of the retaining ring 9.

[0090] According to one example, the axial size may be between 1 mm and 4 mm, and the radial footprint can be between 4 mm and 30 mm depending on functional needs.

[0091] Favorably, an axial size between 3 and 4 mm is used in particular for a gas turbomachine for aircraft.

[0092] Concerning the parts with which the retaining ring 9 cooperates, [Fig.2] illustrates a turbine 7 for an aircraft gas turbomachine 1.

[0093] The turbine 7 comprises the disk adapted to be mounted free to rotate along the general axis on a shaft of the turbomachine 1.

[0094] The turbine 7 comprises the blades 11 regularly distributed circumferentially on the disc 13, each blade 11 comprising a blade-forming part 35 and a root-forming part 37 by which the blade 11 can be engaged in a corresponding receiving location of the disc 13.

[0095] The retaining ring 9 of the turbine 7 is configured to cooperate with the disc 13 and the root-forming parts 37 of the blades 11 so as to block axial movement of the blades 11 relative to the disc 13.

[0096] The turbine 7 has, for each blade 11, a cavity 39 formed in the root-forming part 37 of said blade 11 and / or in the disc 13 to receive by complementary shape the retaining ring 9, the cavity 39 extending radially.

[0097] This allows the retaining ring 9 to be correctly installed so that it is orthogonal to the general axis X and prevents any movement of the blades 11 relative to the disc 13.

[0098] For each blade 11, the cavity 39 comprises a first part formed in the blade 11 and a second complementary part formed in the disc 13. The installation of the retaining ring 9 makes it possible to radially align and maintain the radial alignment of these two parts.

[0099] Each blade 11 is mounted and can only move axially relative to the disc 13. This radial position of the retaining ring 9 thus allows effective blocking.

[0100] The turbine 7 may also comprise two retaining rings 9 and have two corresponding cavities 39, the cavities 39 being axially aligned and surrounding the root-forming part 37 of said blade 11.

[0101] As illustrated in Figures 1 and 2, the turbomachine 1 further comprises flanges 41 axially connecting the discs 13 of two successive turbines 7 except the discs of the first and last turbine 7 of the alignment so as to constitute a rotating assembly.

[0102] In other words, two axially successive discs 13 are connected by an upstream flange 41 and a downstream flange 41, except the discs 13 of the first and last stages.

[0103] The general shape of the retaining ring 9 described above extending along a circle and the particular material distribution of the retaining ring 9 allow it not to create an imbalance during the rotation of the turbine 7.

[0104] It should be noted that a significant imbalance causes vibrations of the turbine 7 and of the turbomachine 1 comprising the turbine 7, as well as misalignment of the sealing elements of the rotor of the turbomachine 1 (moving ring wipers, moving blades and labyrinth rings). The retaining ring 9 is thus particularly advantageous.

[0105] As goes without saying, the invention is not limited to the single embodiment described above as an example; on the contrary, it encompasses all the variant embodiments.

Claims

Claims

1. Retaining ring (9) for axially locking blades (11) of a turbine (7), the retaining ring (9) extending around a general axis (X) of rotation and capable of cooperating with the blades (11) and a disc (13) of the turbine (7) in a retaining position so as to block an axial movement of the blades (11) relative to the disc (13), the retaining ring (9) comprising: - an upstream turn (15) and a downstream turn (17) which are contiguous and stacked axially relative to the general axis (X) in a direction of flow, - a connecting tab (19) connecting the upstream turn (15) and the downstream turn (17) so that the upstream turn (15), the downstream turn (17) and the connecting tab (19) constitute a profiled winding with two contiguous turns,- one or more recesses (27) of material provided in the downstream turn (17) and / or the upstream turn (15) located opposite the connecting tab (19) or located at several symmetrically located locations around an alignment plane (29) defined by the general axis (X) and a diameter of the retaining ring (9) passing through the connecting tab (19).,

2. Retaining ring (9) according to claim 1, having a center of gravity located at the center of a circle defining a general shape of the retaining ring (9), said center being located on the general axis (X) when the retaining ring (9) is in the retaining position.

3. Retaining ring (9) according to one of claims 1 or 2, in which the recess(es) (27) are blind holes.

4. A retaining ring (9) according to claim 3, wherein the recess(es) (27) each have an oblong contour extending along the circumference of the retaining ring (9).

5. Retaining ring (9) according to one of claims 3 or 4, in which the blind hole(s) have an axial depth corresponding to an axial dimension of the upstream turn (15) or the downstream turn (17) or to a smaller dimension.

6. Retaining ring (9) according to one of claims 1 to 5, in which the connecting tab (19) extends in the extension of the turn upstream (15) and also the downstream turn (17) so that the profiled winding of the retaining ring (9) has a substantially constant section along the upstream turn (15), the connecting tab (19) and the downstream turn (17).

7. Turbine (7) for an aircraft gas turbomachine (1), the turbine (7) comprising: - the disk (13) adapted to be mounted free to rotate about the general axis (X) on a shaft of the turbomachine (1), - the blades (11) regularly distributed circumferentially on the disk (13), each blade (11) comprising a blade-forming portion (35) and a root-forming portion (37) by which the blade (11) can be engaged in a corresponding receiving location of the disk (13), - a retaining ring (9) according to one of claims 1 to 6 configured to cooperate with the disk (13) and the root-forming portions (37) of the blades so as to block an axial movement of the blades (11) relative to the disk (13).

8. Turbine (7) according to claim 7, having, for each blade (11), a cavity (39) formed in the root-forming part (37) of said blade (11) and / or in the disc (13) to receive by form-fitting the retaining ring (9), the cavity (39) extending radially.

9. Turbine (7) according to one of claims 7 or 8, comprising two retaining rings (9) and having two corresponding cavities (39), the cavities (39) being axially aligned and surrounding the root-forming part (37) of said blade (11).

10. Gas turbomachine (1) for aircraft comprising at least one turbine (7) according to one of claims 7 to 9 mounted to move in rotation, the turbine (7) being a high pressure turbine (2) or a low pressure turbine (3).

11. Turbomachine (1) according to claim 10, comprising a plurality of turbines (7) mounted to be mobile in rotation and aligned axially, the turbomachine (1) further comprising flanges axially connecting the discs of two successive turbines (7) except the discs of the first and last turbine of the alignment so as to constitute a rotating assembly.

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