FR3081916A1 - MOBILE WHEEL FOR AN AIRCRAFT TURBOMACHINE, INCLUDING AN AXIAL RETAINING RING FIXED TO THE DISC BY AT LEAST ONE LOCKING SYSTEM - Google Patents

Abstract

The invention relates to a movable turbine wheel (20) for an aircraft turbomachine, the wheel comprising a disc (21) and a ring (16) for axial retention of the blades, the ring being fitted with a locking system ( 80) configured to retain the ring axially with respect to the disc. In a locked ring configuration, the locking system (80) assumes a locked position in which its first and second stop elements (76, 86) axially enclose the ring (16) and a fixing flange (60). integral with the disc, the locking system being movable from this locked position to an unlocked position bringing the second stop element (86) axially opposite a passage orifice (66) passing through the flange (60), so as to allow the introduction of the second element (86) into this passage orifice.

Description

MOBILE WHEEL FOR AN AIRCRAFT TURBOMACHINE, COMPRISING AN AXIAL RETAINING RING FIXED TO THE DISC BY AT LEAST ONE LOCKING SYSTEM TECHNICAL FIELD

The invention relates to the field of movable blades for an aircraft turbomachine, and more generally the movable wheels of a turbine equipped with such blades, such as for example the wheels described in document EP 1 264 964 A1.

The invention applies to any type of turbomachine, such as a turbojet or a turboprop.

STATE OF THE PRIOR ART

Movable turbine wheels have been the subject of numerous developments, in particular as regards the means of axial retention of the blades in the grooves situated at the periphery of the turbine disc.

Usually, an axial retention ring is provided, arranged on an upstream and / or downstream side of the turbine disc, in order to form axial stops for the blade roots housed in the grooves of this disc. The axial maintenance of this ring usually requires specific means, for example hooks of complex shapes provided on the blades and on the disc.

If the existing solutions are satisfactory, there nevertheless remains a need for improvement aimed at further facilitating the manufacture of the components of such a wheel, as well as their assembly.

SUMMARY OF THE INVENTION

To respond at least partially to this need, the subject of the invention is a movable wheel for an aircraft turbomachine, the wheel comprising:

- a disc having blade housing grooves;

- A plurality of blades each comprising a blade, and a foot arranged in one of the disc housing grooves; and

- an axial retention ring of the blades.

According to the invention, the ring is equipped with at least one locking system configured to retain the ring axially relative to the disc, this disc being equipped with a ring fixing flange in which the locking system through a passage orifice, the locking system comprising a first stop element, as well as a second stop element connected to the first stop element by a connecting element passing through the ring.

In addition, in a locked configuration of the ring, the locking system adopts a locked position in which its first and second stop elements axially enclose the ring and the fixing flange, the locking system being movable from this locked position. in an unlocked position bringing the second stop element axially opposite the passage orifice, so as to allow the introduction of the second stop element in this passage orifice.

The invention also relates to a method of assembling such a movable wheel, comprising the following successive steps:

- Positioning of the ring in a first intermediate mounting position relative to the disc, position in which the locking system is in its unlocked position with its second stop element arranged at least partly in the passage orifice the mounting flange provided on the disc;

- axial displacement of the ring equipped with its locking system, from its first intermediate mounting position to a second intermediate mounting position in which the locking system is in its unlocked position with its second stop element arranged axially opposite the orifice for the fixing flange provided on the disc; and

- Moving the locking system from its unlocked position to its locked position, so that the first and second stop elements axially enclose the ring and the fixing flange.

The invention thus makes it possible to meet the need formulated above, by providing one or more ring locking systems based on a simple design and operation. The manufacture as well as the assembly of the components of the movable wheel are advantageously improved thereby.

The invention preferably provides at least one of the following optional technical characteristics, taken individually or in combination.

The first stop element has a generally cylindrical shape of circular section, preferably of a screw head, and the second stop element has a generally elongated shape.

The connecting element of the locking system passes through an opening of the ring preferably equipped with a guide ring traversed by the connecting element of the locking system, this ring having, around the opening, two marks allowing identify respectively the locked position and the unlocked position of the locking system. The two brands are then intended to cooperate with an indicator provided on the locking system, and preferably provided on its first stop element.

The ring comprises a countersink receiving the first stop element, so as to drown it entirely or partially in the ring.

The locking system is movable in rotation between its locked position and its unlocked position, preferably along a locking axis on which the connecting element of the locking system is centered.

The passage opening provided on the fixing flange has an oblong shape. However, other shapes are possible, such as a circular shape.

The passage orifice provided on the fixing flange has a closed contour, or preferably opened by a slot for the circumferential introduction of the second abutment element into the passage orifice, the slot opening into this passage orifice and having a width less than the width of the connecting element passing through the passage orifice. Consequently, whether the passage orifice has a contour closed or open by an insertion slot for the second stop element, the connecting element passing through the passage orifice provides an additional function of blocking the rotation of the ring. compared to the disc.

The retention ring comprises a plurality of locking systems regularly distributed circumferentially, for example two, three or four systems distributed uniformly around this axis of rotation.

The invention also relates to an aircraft turbomachine comprising at least one turbine comprising at least one such moving wheel, the turbine preferably being a low pressure turbine. In addition, the turbomachine is preferably a double body turbomachine.

However, the invention could be applied to a compressor, without departing from the scope of the invention.

Other advantages and characteristics of the invention will appear in the detailed non-limiting description below.

BRIEF DESCRIPTION OF THE DRAWINGS

This description will be made with reference to the accompanying drawings, among which;

- Figure 1 is a schematic view in axial section of a turbofan engine according to the invention;

- Figure 2 shows a perspective view of a movable wheel of the low pressure turbine of the turbojet engine shown in the previous figure, the movable wheel being in the form of a preferred embodiment of the invention;

- Figure 3 is an axial half-sectional view of the movable turbine wheel shown in the previous figure;

- Figure 4 shows an enlarged view of that of the previous figure, showing in particular a locking system of the axial retention ring of the blades, with the ring in locked configuration on the disc;

- Figure 5 shows an exploded perspective view of the locking system shown in the previous figure;

- Figure 6 shows a perspective view of the locking system shown in the previous figure, from another angle of view;

- Figure 7, 9 and 11 show different stages of a method of assembling the movable wheel shown in the previous figures;

- Figures 8, 10 and 11a are sectional views taken along lines VIII-VIII, X-X and Xla-XIa respectively in Figures 7, 9 and 11;

- Figure 12 is a view similar to that of Figure 6, with the movable turbine wheel in the form of another preferred embodiment of the invention;

- Figure 13 illustrates a step in a method of assembling the movable wheel shown in the previous figure; and

- Figure 14 is a sectional view taken along the line XIV-XIV of Figure 13.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring firstly to Figure 1, there is shown an aircraft turbomachine 1, according to a preferred embodiment of the invention. This is a double-flow, double-body turbojet engine. However, it could be a turbomachine of another type, for example a turboprop, without departing from the scope of the invention.

The turbomachine 1 has a longitudinal central axis 2 around which its various components extend. It comprises, from upstream to downstream in a main direction 5 of gas flow through this turbomachine, a blower 3, a low pressure compressor 4, a high pressure compressor 6, a combustion chamber 11, a high pressure turbine 7 and a low pressure turbine 8.

Conventionally, after passing through the blower, the air is divided into a central primary flow 12a and a secondary flow 12b which surrounds the primary flow. The primary flow 12a flows in a main stream 14a of gas circulation passing through the compressors 4, 6, the combustion chamber 11 and the turbines 7, 8. The secondary flow 12b flows in turn in a secondary stream 14b delimited radially outwards by a motor housing, surrounded by a nacelle 9.

Figures 2 and 3 show one of the movable wheels 20 of the low pressure turbine 8, but this wheel 20 specific to the invention could also apply to the high pressure turbine 7, without departing from the scope of the invention. In known manner, within a turbine, the movable wheels are provided alternately with distributors (not shown). All the movable wheels of the low pressure turbine 8 can be produced in the manner which will be explained below, or only some of them.

The movable wheel 20 generally comprises a disc 21, a plurality of vanes 18 carried by the disc 21, and a ring 16 for axial retention of the vanes arranged on the upstream side of the disc 21. It is noted that the ring 16 specific to the he invention is intended to ensure the axial retention of the blades 18 upstream, and that their retention downstream is ensured by another device (not shown). This other device can be a ring similar to the ring 16, just as such a ring 16 specific to the invention could only be provided downstream of the disc 21, to ensure the axial retention of the blades 18 towards the downstream.

The blades 18 are distributed circumferentially around the disc 21. Each of them comprises in a radial direction 23 in relation to the central axis 2, going from the inside to the outside, a blade root 24, a stilt 26, a platform 28 and a blade 30 constituting the aerodynamic part of the blade. The blade root 24 has an outer dovetail shape called "fir" or "bulb", allowing its insertion into a blade housing groove 58 provided at the periphery of the turbine disc 21. The stilt 26 usually has a small thickness in a circumferential direction 32, while the platform 28 extends on either side of stilt 26 in this same circumferential direction 32.

With its outer surface 29, the platform 28 delimits radially inward the main vein 14a. The platform 28 has two opposite axial ends, each forming a spoiler. It is an upstream spoiler 44 located upstream of the leading edge of the blade 30, and a downstream spoiler 45 located downstream of the trailing edge of this blade.

The disc 21 has a main part 46 of revolution about an axis 2, also corresponding to the axis of rotation of the movable wheel 20 in operation. This main part 46 has a recess 48 centered on the axis 2, defined by an inner periphery part 50 of the disc. Its thickness then reduces in the direction of an outer peripheral part 52 of the disc, defining the blade housing grooves 58, of axial or oblique orientation. The disc 21 includes other elements such as fixing flanges (not shown) allowing its connection to other movable wheels of the turbine, but also at least one ring fixing flange 16 projecting from the outer peripheral part. 52. More specifically, the fixing flange 60 takes the form of a tongue extending axially spaced from the main part of the disc 46, an axial space 62 being provided between these two elements 46, 60. The fixing flange 60 thus protrudes radially inwards from an upstream edge of the outer peripheral part 52 of the disc, as can be seen in FIG. 3. Its circumferential extent is small, for example reduced to an angular sector from 3 to 15 °, as well as its radial extent. In fact, the radially internal edge of the fixing flange 60 is preferably covered axially by the retaining ring 16.

If a single fixing flange 60 is shown in FIG. 3, it is noted that several of these flanges can be provided on the disc 21, preferably in a number identical to the number of ring locking systems, including the one of them will be described below. Each flange 60 for fixing the ring 16 is then associated with one of the locking systems, these couples being preferably distributed evenly, circumferentially. Their number can be set between two and four.

In the locked configuration of the ring 16 as shown in FIGS. 2 and 3, this ring is located radially under the upstream spoiler 44. The radially external part of the ring 16 is arranged in axial support on an upstream face of the part outer device 52 of the disc 21, so as to axially retain the blades at their feet 24 housed in the grooves 58. In this regard, it is noted that each blade housing groove 58 remains open radially outward for allow the stilt 26 of the dawn to pass, as is known from the prior art.

One of the features of the invention resides in the manner of ensuring the axial locking of the ring 16 with respect to the disc 21. As mentioned previously, one or more locking systems 64 specific to the invention are used, each cooperating with a fixing flange 60 provided on the disc. One of these couples will now be detailed with reference to Figures 4 to 6 showing the ring 16 in its locked configuration.

First of all, the fixing flange 60 is crossed axially by a passage orifice 66, preferably of oblong shape. At one of the circumferential ends of the orifice 66, the flange 60 is provided with a slot 68 which is circumferentially oriented and opens out in the orifice 66. The slot 68 has a width L'1, in the radial direction 23, which is less than the width L'3 of the orifice 66 in this same radial direction. In this preferred embodiment, the contour of the passage orifice 66 is therefore not closed, but open due to the presence of the slot 68 also leading to a circumferential edge of the fixing flange 60.

The ring 16, pressed axially against the upstream surface of the fixing flange 60, has an opening 70 which is preferably of circular shape. It receives a guide ring 72, mounted tightly in this opening 70. Around this, there is provided a countersink 74 partially or entirely embedding a first abutment element 76 of a locking system 80, in the axial direction.

This system 80 in fact comprises the first abutment element 76, preferably in the form of a screw head revealing, on its upstream surface, a notch 82 to allow it to rotate along a locking axis 84 of direction parallel to the axis 2. The first stop element 76 forms the upstream part of the system 80, while its downstream part is formed by a second stop element 86, preferably of generally elongated shape. This shape can be generally rectangular, oval or oblong. In the locked configuration of the ring, the system 80 adopts a locked position bringing its second stop element 86 in a substantially radial orientation, namely substantially orthogonal to the direction of the length L3 of the passage orifice 66. Consequently, at its ends, the second stop element 86 is in abutment against the downstream surface of the fixing flange 60, since the length L2 of the second element 86 is greater than the width L'3 of the orifice of passage 66. Its length L2 is on the other hand less than the length L3 of the passage orifice 66, and its width L'2 is also less than the width L'3 of this passage orifice 66.

The two abutment elements 76, 86 are connected by a connecting element 88, centered on the locking pin 84. The connecting element 88 has a preferably circular section, and it passes through the guide ring 72. Also, this connecting element 88 is inserted into the fixing flange 60, through the passage orifice 66. The two axial ends of the connecting element 88 are respectively integral with the two abutment elements 76, 86, so that 'A rotation of the first element 76 leads to a same rotation of the second element 86, along the locking axis 84. Its axial length corresponds substantially to the sum of the thicknesses of the opening 70 and the passage orifice 66 , while its width L'4, corresponding to its diameter, is greater than the width L'1 of the slot 68. On the other hand, this width L'4 is substantially equal to the inside diameter of the ring 72, as well as to the width L'3 of the passage orifice 66.

Thanks to this design, in the locked configuration of the ring 16 in which the system 80 is in the locked position, the two abutment elements 76, 86 axially enclose the assembly formed by the ring 16 and the fixing flange 60. These two elements 16, 60 are in fact pressed against each other in the axial direction, causing an axial locking of the ring 16 on the disc 21. In this same configuration, the ring 16 is kept in rotation by relative to the disc 21 by the friction forces exerted between the upstream surface of the second stop member 86 arranged in the axial space 62, and the downstream surface of the fixing flange 60. In addition, due to the width L '4 consequent of the connecting element 88, the latter proves anyway blocked by the circumferential ends of the passage orifice 66, thus creating an anti-rotation function for the ring equipped with the locking system 80.

As mentioned above, the locking system 80 on board the ring 16 is movable in rotation along the locking axis 84, between the above-mentioned locked position shown in FIGS. 4 to 6, and an unlocked position. To allow an operator to clearly identify the position in which the system 80 is located, the ring 16 is provided, on its upstream surface around its opening 70, with two marks 90 allowing these two positions to be identified respectively. These two marks 90, spaced at 90 ° from each other, cooperate with an indicator formed by the notch 82 of the first stop member 76, this notch being intended to receive a tool for the rotation of the system 80 along the locking axis 84.

The unlocked position is shown in Figures 11 and 11a, and obtained by simply rotating the locking system 80 90 ° along the axis 84, via the notch 82 provided for this purpose on the first stop member 76. This a quarter-turn rotation has the consequence of bringing the second stop element 86 axially opposite the passage orifice 66 of the fixing flange 60, that is to say in a substantially circumferential orientation in which its length L2 is oriented substantially parallel to the length L3 of the orifice 66. Thus, due to the change in orientation of the second abutment element 86, the latter can be introduced axially into the orifice 66, then extracted from the latter during a ring removal process. For the assembly of this ring 16 on the disc 21, reverse operations are carried out, as will now be detailed with reference to Figures 7 to 11a.

Firstly with reference to FIGS. 7 and 8, a first step of the assembly process is illustrated. It consists in bringing the ring 16 into a position centered on the axis 2, while being slightly offset circumferentially and axially with respect to its locked configuration as adopted in operation. In fact, it is first sought to introduce the second stop element 86 into the slot 68, with the system 80 in the unlocked position. To do this, the ring 16 equipped with the system 80 is rotated along the axis 2, which leads the second stop element 86 to be introduced into the slot 68 having a parallel orientation. As this rotation of the ring 16 continues, the second stop element 86 is gradually introduced into the passage orifice 66, always retaining its circumferential orientation dictated by the unlocked position of the system 80. L 'ring 16 then reaches a first intermediate position shown in Figures 9 and 10, wherein the second stop member 86 is housed in the orifice 66, for example projecting axially on either side thereof. In this first intermediate position of the ring 16 relative to the disc 21, the system 80 is always in the unlocked position, and the ring 16 is located upstream relative to its locked position.

Then, there is an axial displacement of the ring 16, so that it reaches a second intermediate position shown in Figures 11 and 11a. In this second intermediate position of the ring, the system 80 is always in the unlocked position, and its second stop element 86 is arranged further downstream, namely axially opposite the passage orifice 66. In d ' other words, the second element 86 is always oriented circumferentially, but outside the orifice 66 from which it was extracted, being now housed in the axial space 62 defined between the main disc part 46 and the fixing flange 60.

In this second intermediate position, the ring 16 is correctly arranged axially and circumferentially with respect to the disc 21, but it is not yet locked. To reach the locked configuration of the ring, it suffices to move the system 80 to its locked position, by simply rotating the first stop element 76 90 ° along the axis 84, via the notch 82 provided for this purpose. . The consequence of this quarter-turn rotation is to bring the second stop element 86 into an axial stop against the downstream surface of the fixing flange 60. Once this last operation has been carried out, the first and second stop elements 76, 86 axially enclose the assembly formed by the ring 16 and the flange 60, pressed one against the other.

This embodiment is preferably adopted when the environment offers only a limited axial space for introducing and manipulating the ring 16 near the disc 21. The presence of the slot 68 for the circumferential introduction of the second stop element 86 allows to cope with this confined space. However, when this space offers more room for axially manipulating the ring 16, another preferred embodiment can be adopted, as shown in FIG. 12.

In this other embodiment, the passage orifice 66 has a closed contour, and no longer requires the presence of the slot 68. The assembly of the ring then no longer requires circumferential movement relative to the disc, since this ring can be placed sufficiently set back from the fixing flange 60, so that the second stop element 86 is arranged axially opposite the passage orifice 66. Then, the ring is moved axially to successively adopt the first position intermediate of FIGS. 9 and 10 in which the second stop element 86 penetrates into the passage orifice 66, then the second intermediate position of FIGS. 11 and IIa in which the second stop element 86 is extracted from this same orifice 66 to penetrate in space 62. Finally, the assembly process ends with the rotation of the system 80, to bring it into its locked position.

Of course, various modifications can be made by those skilled in the art to the invention which has just been described, only by way of nonlimiting examples, and the scope of which is defined by the appended claims.

Claims (10)

1. Movable wheel (20) for an aircraft turbomachine, the wheel comprising: - A disc (21) having grooves (58) for housing the blades; - A plurality of blades (18) each comprising a blade (30), and a foot (24) arranged in one of the housing grooves (58) of the disc (21); and - a ring (16) for axial retention of the blades (18), characterized in that the ring (16) is equipped with at least one locking system (80) configured to retain the ring (16) axially relative to to the disc (21), this disc (21) being equipped with a flange (60) for fixing the ring in which the locking system (80) is inserted through a passage orifice (66), the system locking device (80) comprising a first stop element (76), as well as a second stop element (86) connected to the first stop element (76) by a connecting element (88), and in that in a locked configuration of the ring (16), the locking system (80) adopts a locked position in which its first and second stop elements (76, 86) axially enclose the ring (16) and the fixing flange (60 ), the locking system being movable from this locked position to an unlocked position bringing the second element stop (86) axially opposite the passage orifice (66), so as to allow the introduction of the second stop element (86) in this passage orifice (66). 2. Movable wheel according to claim 1, characterized in that the first stop element (76) has a generally cylindrical shape of circular section, preferably of a screw head, and in that the second stop element (86) has a generally elongated shape. 3. Movable wheel according to claim 1 or claim 2, characterized in that the connecting element (88) of the locking system passes through an opening (70) of the ring preferably equipped with a guide ring (72 ) traversed by the connecting element (88) of the locking system, this ring (16) having, around the opening (70), two marks (90) making it possible to identify the locked position and the unlocked position of the system respectively lock (80). 4. Movable wheel according to claim 3, characterized in that the opening of the ring (16) comprises a countersink (74) receiving the first stop element (76). 5. Movable wheel according to any one of the preceding claims, characterized in that the locking system (80) is rotatable between its locked position and its unlocked position, preferably along a locking pin (84) on which is centered the connecting element (88) of the locking system (80). 6. Movable wheel according to any one of the preceding claims, characterized in that the passage orifice (66) provided on the fixing flange (60) has an oblong shape. 7. Movable wheel according to any one of the preceding claims, characterized in that the passage orifice (66) provided on the fixing flange (60) has a closed contour, or preferably opened by a slot (68) d circumferential introduction of the second stop element (86) into the passage opening, the slot (68) opening into this passage opening (66) and having a width (L'1) smaller than the width (L'4) of the connecting element (88) passing through the passage orifice (66). 8. Movable wheel according to any one of the preceding claims, characterized in that the ring (16) comprises a plurality of locking systems (80) regularly distributed circumferentially. 9. aircraft turbomachine (1) comprising at least one turbine (7, 8) comprising at least one movable wheel (20) according to any one of the preceding claims, the turbine preferably being a low pressure turbine. 10. A method of assembling a movable wheel (20) according to any one of claims 1 to 8, characterized in that it comprises the following successive steps: - Positioning of the ring (16) in a first intermediate mounting position relative to the disc (21), position in which the locking system (80) is in its unlocked position with its second stop element (86 ) arranged at least partly in the passage orifice (66) of the fixing flange (60) provided on the disc (21); - axial displacement of the ring (16) equipped with its locking system (80), from its first intermediate mounting position to a second intermediate mounting position in which the locking system (80) is in its unlocked position with its second stop element (86) arranged axially opposite the passage orifice (66) of the fixing flange (60) provided on the disc (21); and - displacement of the locking system (80) from its unlocked position to its locked position, so that the first and second stop elements (76, 86) axially enclose the ring (16) and the fixing flange (60 ).