Turbine overspeed disconnect device for turbine engines

Abstract

The invention relates to an assembly for a turbomachine turbine (10) having a longitudinal axis (A-A), comprising: a rotor disk (12) of the turbine, centered on the longitudinal axis; a shaft (14) of the turbine, centered on the longitudinal axis and rotated by the rotor disk; a first member for transmitting torque from the rotor disk to the shaft, the rotor disk being fixed in translation relative to the shaft in the direction of the longitudinal axis by a member (22) screwed onto the shaft; and a second member for transmitting torque from the rotor disk to the screwing member, wherein the unscrewing direction of the screwing member is identical to the rotation direction of the rotor disk in operation, and the second torque transmission member is configured to transmit rotational torque from the rotor disk to the screwing member when the first torque transmission member stops transmitting the torque from the rotor disk to the shaft.

Description

Technical Field

[0001] The invention relates to an assembly for a turbine of a turbine engine.

[0002] More precisely, the invention relates to an assembly for a turbine of a turbine engine, comprising means for disengaging the turbine in the event of an overspeed. Background Art

[0003] In a turbine engine, the fan is driven in rotation by a turbine having a rotor disk equipped with moving blades and connected to a low-pressure compressor. If the shaft connecting the fan to the turbine breaks, the drag torque on the turbine is suddenly eliminated, while the engine airflow continues to transfer energy to the rotor disk. This can cause the speed of the rotor disk to increase uncontrolled and therefore cause the risk of bursting, resulting in the release of high-energy flow. In this case, the turbine is in "overspeed".

[0004] EP1640564 proposes a device that uses downstream displacement of the turbine to limit the overspeed of the turbine. The device includes a member that destroys the moving blades arranged in the downstream stator blades of the turbine. However, the downstream displacement of the rotor disk can be prevented by means of the translational fixation of the turbine relative to its rotation axis. Therefore, the moving blades will not be damaged by the destructive member. Therefore, such a device lacks effectiveness and reliability in limiting overspeed. Summary of the invention

[0005] One object of the invention is to ensure that the turbine moves downstream in the event of a shaft failure so that the annular row of moving blades comes into contact with the annular row of stator blades, thereby allowing the annular row of moving blades to be destroyed by the annular row of stator blades, thus slowing down the speed of the turbine.

[0006] Another object of the invention is to limit the overspeed of the turbine in the event of a shaft failure in a reliable and effective manner.

[0007] To this end, the invention proposes an assembly for a turbine of a turbine engine having a longitudinal axis, comprising:

[0008] - a rotor disk of the turbine, centered on the longitudinal axis,

[0009] - the shaft of the turbine, which is centered on the longitudinal axis and is driven in rotation by the rotor disk,

[0010] - a first member for transmitting torque from the rotor disk to the shaft, wherein the rotor disk is locked in translation relative to the shaft in the direction of the longitudinal axis by means of a screwing member on the shaft, and

[0011] a second member transmitting torque from the rotor disk to the screwing component, wherein the screwing direction of the screwing component is identical to the rotation direction of the rotor disk during operation, and the second member transmitting torque is configured to transmit rotational torque from the rotor disk to the screwing component when the first member transmitting torque stops transmitting torque from the rotor disk to the shaft.

[0012] The invention is advantageous in that the unscrewing direction of the screwing part is the same as the rotation direction, so that when the first member transmitting the torque stops transmitting the torque from the rotor disk to the shaft, the second member transmitting causes the screwing part to unscrew. As a result, the turbine is no longer constrained in the axial direction and can move backwards, thereby causing damage to its moving blades relative to the stator of the turbine engine. This prevents the turbine from overspeeding, because the damaged moving blades no longer provide energy. Therefore, the invention provides a reliable and effective overspeed limitation of the turbine in the event of a loss of power transmission from the shaft to the rotor disk.

[0013] In one embodiment, the first member for transmitting torque may include a first longitudinal rack formed on the shaft and distributed circumferentially around the longitudinal axis and a second longitudinal rack engaged with the first rack and formed on the inner ring side of the rotor disk.

[0014] If the first rack and / or the second rack are broken or damaged, the first member transmitting torque may stop transmitting torque from the rotor disk to the shaft.

[0015] The second member for transmitting torque may include a ring centered on the longitudinal axis and including a first latch cooperating with a groove formed in the screw component and a second latch cooperating with a groove formed in the rotor disk.

[0016] The first latch allows the screwing component to rotate when the ring is rotated by the rotor disk through the second latch, for example, when the first member transmitting torque stops transmitting torque from the rotor disk to the shaft.

[0017] In one embodiment, the circumferential gap between the first rack and the second rack may be smaller than the sum of the circumferential gap between the second latch pin and the rotor disk and the circumferential gap between the first latch pin and the screwing component.

[0018] Thus, the transmission of rotation from the rotor disk to the shaft is facilitated and the screwing component does not rotate while the first means of transmission are able to transmit the rotation from the rotor disk to the shaft.

[0019] In one embodiment, the ring may comprise an annular section, wherein a first latch extends upstream and a second latch is arranged downstream of the first latch.

[0020] Additionally, at least one of the first latch and the second latch may comprise a concave circular portion for connecting to the ring segment. This allows for better mechanical strength of the ring.

[0021] The second latch pin may extend primarily in the direction of the longitudinal axis.The second latch pin may extend downstream in the direction of the longitudinal axis.

[0022] The second latch may extend primarily in a radial direction perpendicular to the longitudinal axis.

[0023] The number of second latches may be greater than the number of grooves in the rotor disk.

[0024] The number of the first latches may be greater than the number of the grooves in the screw component.

[0025] The fact that the number of latches is greater than the number of grooves facilitates a tight fit of the ring to the rotor disk on the one hand and to the screwed component on the other hand.

[0026] The number of the second latches may be smaller than the number of the first latches.

[0027] The ring can be mounted in different ways. For example, the ring can be mounted around the screwing part. The ring can be locked in translation in the downstream direction by means of a circlip mounted in a groove in the screwing part.

[0028] In one embodiment, an annular space may be provided immediately downstream of the screwing component.The longitudinal dimension of the annular space may be greater than or equal to the longitudinal distance between the moving blades connected to the rotor disk and the stator blades immediately downstream of the turbine.

[0029] The turbine can therefore be moved back far enough for the stator blades to come into contact with the blades connected to the rotor disk.

[0030] The shaft may be connected to a low pressure compressor of the turbine engine.

[0031] According to another aspect, the invention provides a turbine, such as a low-pressure turbine, comprising the above-mentioned assembly.

[0032] In one embodiment, the turbine may extend about a longitudinal axis and include a stator and a rotor rotatably mounted in the stator. The rotor may include an assembly as described above, wherein the ring may be locked in translation downstream by a circlip mounted in a groove in the screwing member.

[0033] An annular space may be arranged immediately downstream of the screwing component, wherein the longitudinal dimension of the annular space is greater than or equal to the longitudinal distance between the moving blades connected to the rotor disk and the stator blades located immediately downstream of the moving blades.

[0034] According to another aspect, the invention proposes a turbine engine, for example an aircraft turbojet engine, equipped with the above-described assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1A partial cross-sectional view of a turbine of a turbine engine is shown.

[0036] Figure 2 A partial cross-sectional view of a first example of an assembly according to the invention is shown.

[0037] Figure 3 A perspective view of a first example of an assembly according to the invention is shown.

[0038] Figure 4 Figures a and b in FIG. 1 respectively show a first example of a ring according to the present invention and a second example of a ring according to the present invention.

[0039] Figure 5 The invention is shown as follows Figure 4 An instance of a component of the ring of a graph in .

[0040] Figure 6 The invention is shown as follows Figure 4 An instance of a component of the ring in graph b. DETAILED DESCRIPTION

[0041] refer to Figures 1 to 3 , the turbine 10 comprises a plurality of stator blades 24 connected to a stationary casing 20, and a plurality of moving blades 26 connected to a rotor disk 12 rotatable about a longitudinal rotation axis AA. Each of the stator blades 24 is equipped with a convex protrusion 28 facing upstream of the inner platform and shaped to shear the moving blade 26 when it contacts the protrusion. Specifically, the protrusion 28 is curved, with the convex surface of the blade 24 facing upstream.

[0042] The rotor disk 12 is arranged to rotate a shaft 14 of the turbine 10. For example, the shaft 14 may be connected to a low-pressure compressor of a turbine engine equipped with the turbine 10. The rotor disk 12 comprises an annular section arranged around the shaft 14 and comprises a rack 16 circumferentially distributed around the axis of rotation AA on the inner side (ie, radially oriented inward). The rack 16 extends over a longitudinal portion of the inner side of the rotor disk 12. The shaft 14 comprises a rack 18 on its outer side, which is circumferentially distributed around the axis of rotation AA and engages with the rack 16 of the rotor disk 12 for transmitting torque from the rotor disk to the shaft 14. The rack 18 extends over a longitudinal portion of the shaft 14.

[0043] The rotor disk 12 is held in translation in the direction of the axis of rotation AA by a nut 22 which is screwed onto the shaft 14 and bears against a flange 30 of the rotor disk 12. The nut 22 is mounted on the shaft 14 in such a way that the unscrewing direction of the nut is the same as the direction of rotation of the turbine 10. For this purpose, a thread is provided in the shaft 14 to ensure this unscrewing direction.

[0044] If the shaft 14 or the connection between the shaft 14 and the rotor disk 14 fails, there is a risk that the turbine 10 will uncontrollably overspeed due to the hot gases from the upstream combustion chamber driving the blades to rotate. In order to limit overspeed, the convex protrusions 28 of the stator blades 24 are arranged to shear and feather the moving blades 26 to reduce or even eliminate the energy received by the turbine 10. These protrusions are formed at the leading edge of the blades. More precisely, the leading edge of each blade thus includes a convex surface.

[0045] In order to ensure that the protrusions 28 are in contact with the moving blades 24 , the turbine comprises a ring 32 configured to unscrew the nut 22 in the event of damage to the shaft 14 , thereby releasing the rotor disk 12 in translation in the direction of the axis of rotation AA.

[0046] The ring 32 is annular and is arranged between the nut 22 and the rotor disk 12. The ring 32 comprises first latches 34 which are distributed circumferentially around the axis of rotation AA and which engage with grooves provided in the shaft 14. The ring 32 also comprises second latches 36 which are distributed circumferentially around the axis of rotation AA and which engage with grooves provided in the rotor disk 12.

[0047] When the shaft 14 fails or the racks 16 and 18 are disengaged from each other, the ring 32 transmits the rotation of the rotor disk 12 to the nut 22. The nut 22 is thus unscrewed by the rotation of the turbine 10, thereby releasing the turbine 10 in translation. The turbine 10 moves downstream along the axis of rotation AA, so that the moving blades 26 are cut off by the protrusions 28 of the stator blades 24 downstream of the moving blades 26.

[0048] The turbine 10 comprises a space downstream of the nut 22, the length of which is greater than the distance between the protrusion 28 of the stator blade 24 and the moving blade 26. For example, the length of the space may be greater than or equal to twice the distance.

[0049] The circumferential clearance between the rack 16 of the rotor disk 12 and the rack 18 of the shaft 14 may be smaller than the sum of the circumferential clearance between the second latch 36 and the rotor disk 12 and the circumferential clearance between the first latch 34 and the nut 22 .

[0050] Furthermore, an annular circlip 38 is arranged downstream of the ring 32 in a position provided in the nut 22 and protrudes in the radial direction away from the nut 22. The circlip 38 holds the ring 32 translationally fixed in the direction of the axis of rotation AA.

[0051] Figure 4 Figure a and Figure 5 Display can be installed on Figures 1 to 3A first example of an embodiment of a ring 100 in a turbine 10 in FIG. The ring 100 comprises an annular segment 102, for example, the radius of which is greater than the outer radius of the nut 22. The ring 100 comprises, on the one hand, a first latch 104 and, on the other hand, a second latch 106. The first latch 104 extends upstream from the annular segment 102 in the direction of the axis of rotation AA and engages with a groove provided in the nut 22. Similarly, the second latch 106 extends downstream from the annular segment 102 in the direction of the axis of rotation AA and engages with a groove provided in the rotor disk 12.

[0052] The number of first latches 104 is smaller than the number of grooves in the nut 22, and the number of second latches 106 is smaller than the number of grooves in the rotor disk 12. This makes it easier to fit the ring 100 into the rotor disk 12 on the one hand, and to fit the ring into the nut 22 on the other hand. For example, the number of grooves in the nut 22 may be equal to or greater than twice the number of first latches 104. The number of grooves in the rotor disk 12 may be twice the number of second latches 106. In addition, the number of first latches 104 may be smaller than the number of second latches 106.

[0053] Each of the first latches 104 has a circular connection with the ring segment 102. Similarly, each of the second latches 106 has a circular connection with the ring segment 102. This improves the mechanical strength of the ring 32.

[0054] Furthermore, the ring 100 has an annular shoulder 108 carried by the annular section 102 and delimited by the first bolt 10 , said shoulder 108 bearing upstream against an annular shoulder of the nut 22 .

[0055] The ring 100 may be made of the same material as the nut 22 and / or the rotor disk 12 .

[0056] Figure 4 Figure b and Figure 6 Display can be installed on Figures 1 to 3 A second example of an embodiment of a ring 200 in a turbine 10 in FIG. The ring 200 comprises an annular section 202, for example, the radius of which is greater than the outer radius of the nut 22. The ring 200 comprises, on the one hand, a first latch 204 and, on the other hand, a second latch 206. The first latch 204 extends in the direction of the axis of rotation AA and engages with a groove provided in the nut 22. Similarly, the second latch 206 extends in the direction of the axis of rotation AA and engages with a groove provided in the rotor disk 12.

[0057] The number of first latches 204 is smaller than the number of grooves in the nut 22, and the number of second latches 206 is smaller than the number of grooves in the rotor disk 12. This makes it easier to fit the ring 200 into the rotor disk 12 on the one hand, and to fit the ring into the nut 22 on the other hand. For example, the number of grooves in the nut 22 may be equal to or greater than twice the number of first latches 204. The number of grooves in the rotor disk 12 may be twice the number of second latches 206. In addition, the number of first latches 204 may be smaller than the number of second latches 206.

[0058] Each of the first latches 204 has a circular connection with the ring segment 102. Similarly, each of the second latches 106 has a circular connection with the ring segment 202. This improves the mechanical strength of the ring 32.

Claims

1. An assembly for a turbine engine turbine (10) having a longitudinal axis (AA), comprising: - a rotor disk (12) of the turbine, centered on said longitudinal axis, - a turbine shaft (14), centered on said longitudinal axis and driven in rotation by said rotor disk, - a first member for transmitting torque from the rotor disk (12) to the shaft (14), wherein the rotor disk (12) is locked in translation relative to the shaft (14) in the direction of the longitudinal axis by means of a screwing part (22) screwed onto the shaft (14), and - a second member for transmitting torque from the rotor disk (12) to the screwing component (22), wherein the screwing direction of the screwing component (22) is the same as the rotation direction of the rotor disk (12) during operation, and the second member for transmitting torque is configured to transmit torque from the rotor disk (12) to the screwing component (22) when the first member for transmitting torque stops transmitting torque from the rotor disk (12) to the shaft (14).

2. The assembly according to claim 1, characterized in that The first means for transmitting torque comprises a first longitudinal rack (18) and a second longitudinal rack (16), wherein the first longitudinal rack is formed on the shaft (14) and is distributed circumferentially around the longitudinal axis (AA), and the second longitudinal rack is engaged with the first longitudinal rack and is formed in the inner ring side of the rotor disk (12).

3. The assembly according to claim 2, characterized in that A second member for transmitting torque comprises a ring (32, 100, 200) centered on the longitudinal axis (AA) and comprising a first latch (34, 104, 204) cooperating with a groove formed in the screw component (22) and a second latch (36, 106, 206) cooperating with a groove formed in the rotor disk (12).

4. The assembly according to claim 3, characterized in that The circumferential gap between the first longitudinal rack (18) and the second longitudinal rack (16) is smaller than the sum of the circumferential gap between the second latch (36) and the rotor disk (12) and the circumferential gap between the first latch (34) and the screwing component (22).

5. The assembly according to claim 3 or 4, characterized in that The ring (100, 200) comprises an annular section (102, 202), the first latch (104, 204) extending upstream and the second latch (106, 206) arranged downstream of the first latch, at least one of the first latch and the second latch comprising a concave circular portion for connecting to the annular section.

6. The assembly according to claim 3, characterized in that The second latch (106) extends mainly in the direction of the longitudinal axis (AA), or mainly in a radial direction perpendicular to the longitudinal axis (AA).

7. The assembly according to claim 3, characterized in that The number of the second latches (36, 106, 206) is smaller than the number of the first latches (34, 104, 204).

8. The assembly according to claim 3, characterized in that The ring (32, 100, 200) is mounted around the screw component (22).

9. A turbine extending about a longitudinal axis (AA), comprising a stator and a rotor rotatably mounted in the stator, wherein the rotor comprises an assembly according to any one of claims 3 to 8, wherein the ring is locked in translation downstream by means of a circlip (38) mounted in a groove in the screw-on part (22).

10. The turbine according to claim 9, characterized in that An annular space is arranged immediately downstream of the screwing component (22), wherein the longitudinal dimension of the annular space is greater than or equal to the longitudinal distance between a moving blade (26) connected to the rotor disk (12) and a stator blade (24) located immediately downstream of the moving blade (26).

11. A turbine engine, characterized in that It is equipped with an assembly according to any one of claims 1 to 8 or with a turbine according to claim 9 or 10.

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