MODULE FOR AN AIRCRAFT TURBOMACHINE

Abstract

Module (30) for an aircraft turbomachine (10), this module (30) comprising: - a first annular bearing support (32) extending about an axis (A) and including a first annular mounting flange (32a), - a second annular bearing support (34) extending about the axis (A) and including a second annular mounting flange (34a), the first and second flanges (32a, 34a) being adapted to be axially pressed against each other and to be fastened together by shear screws (42), characterized in that one of the bearing supports (32) carries a retaining ring (86) extending around this bearing support and at least partially around the shear screws (42), and which is adapted to retain at least a portion of these shear screws (42) in the event of failure of the shear screws (42). Figure for the abbreviation: Figure 5

Description

Title of the invention: MODULE FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention

[0001] The present invention relates to a module for an aircraft turbomachine, as well as a turbomachine comprising such a module. Technical background

[0002] The prior art includes in particular document EP-B1-2 721 260.

[0003] An aircraft turbomachine includes a gas generator which conventionally comprises, from upstream to downstream, with reference to the flow of gases in the turbomachine, at least one compressor, an annular combustion chamber and at least one turbine.

[0004] In the case of a twin-spool turbofan engine, with low-pressure and high-pressure components respectively, the gas generator comprises successively a low-pressure compressor, a high-pressure compressor, the combustion chamber, a high-pressure turbine, and a low-pressure turbine. The gas generator defines a first annular flow path of gas, called the primary flow, which passes through the compressors, the combustion chamber, and the turbines.

[0005] The rotor of the high-pressure compressor is connected to the rotor of the high-pressure turbine by a high-pressure shaft. The rotor of the low-pressure compressor is connected to the rotor of the low-pressure turbine by a low-pressure shaft which passes through the high-pressure shaft and drives a shaft of a propulsion propeller generally located upstream of the gas generator.

[0006] When this propeller is enclosed and therefore surrounded by an annular casing, this propeller is called a blower and generates an airflow, called a secondary flow, which flows around the gas generator.

[0007] The propeller shaft and the low-pressure shaft are guided by bearings housed in a lubrication enclosure. This enclosure is surrounded by the first channel and is at least partially delimited by bearing supports. A first rolling bearing located upstream is supported by a first bearing support, and a second rolling bearing located downstream is supported by a second bearing support. These bearing supports have annular flanges that are radially oriented and axially applied to each other and to an annular flange of a stator housing.

[0008] The lubrication chamber is designed to lubricate the bearings and maintain an oily atmosphere around them. The oil is supplied to the chamber via a supply circuit.

[0009] The propeller includes blades that are susceptible to breakage, although this phenomenon is extremely rare. In such a case, a significant imbalance appears on the propeller shaft, generating cyclic loads and vibrations that the upstream bearing transmits to the stator, with a considerable risk of damage.

[0010] To limit the forces transmitted to the stator in the presence of a large imbalance, a shear screw decoupling device is known from document FR-A1-2 831 624. In practice, the second bearing support is fixed to the stator housing by non-shear screws, and the first bearing support is fixed to the second bearing support by shear screws to form a connection that can be broken. These so-called "fuse" screws, whose operation is fully described in the aforementioned document, have a reduced cross-section portion that is likely to break beyond a predetermined mechanical tensile force and thus achieve the decoupling of the bearing supports. In this situation of shear screw failure, the first bearing support is no longer axially restrained. It moves axially upstream and therefore moves axially away from the second bearing support. This is especially true when the bearing supported by the first bearing support is a roller bearing, which does not provide axial restraint to the bearing support when it is separated from the second bearing support.

[0011] This phenomenon is problematic because the housing continues to be supplied with oil by the aforementioned circuit, and the oil that accumulates in the housing is likely to pass through the annular passage formed between the bearing support flanges, which have moved axially apart. The oil then spills into the engine, generating contamination. This oil can reach the first air intake from which air is drawn to supply air to the aircraft equipped with the turbomachine. There is therefore a risk that the aircraft will be supplied with polluted air, or even with unpleasant fumes and odors.

[0012] Moreover, there is currently no effective solution for retaining fusible screws after breakage, so it is not impossible that the screws may be present in the enclosure under the vein without remaining attached to their initial support.

[0013] The invention proposes an improvement which makes it possible to provide a solution to at least some of the problems mentioned above. Summary of the invention

[0014] The invention relates to a module for an aircraft turbomachine, this module comprising:

[0015] - a first annular bearing support which extends around an axis and which comprises a first annular fixing flange,

[0016] - a second annular bearing support which extends around the axis and which comprises a second annular fixing flange, the first and second flanges being suitable for axial application against each other and for being fixed together by shear screws,

[0017] characterized in that one of the bearing supports carries a retaining ring which extends around this bearing support and at least partly around the fusible screws, and which is capable of retaining at least part of these fusible screws in the event of breakage of the fusible screws.

[0018] In normal operation, the shear screws ensure the axial retention of the first bearing support relative to the second bearing support. If the shear screws break, the bearing supports separate and move axially apart. Portions of the shear screws are then likely to detach from the bearing supports. At least some of these portions can be retained by the ring according to the invention, which is integral with one of the bearing supports. The risk of these shear screw portions entering the motor shaft is therefore limited.

[0019] The module according to the invention may comprise one or more of the following features, taken individually or in combination with each other: • the retaining ring is formed by a sheet of metal; • the retaining ring comprises a first axial end fixed to the bearing support which carries it, and a second opposite axial end which is free and is located at a radial distance from this bearing support; • the first end of the ring is fixed to the bearing support by axial screws which pass through holes in this first end and in the bearing support; • the first end of the ring is fixed to an annular rib of the first bearing support, this rib extending radially outwards; • the first end of the ring is oriented radially inwards so that a free peripheral edge of this end is oriented radially inwards; • the retaining ring has a general L-shape and comprises a first radial wall connected to the bearing support which carries it, and a second cylindrical wall which extends axially from the outer periphery of the first wall and around at least part of the shear screws; • The module further includes a lubrication chamber which is at least partially delimited by the first bearing support, this lubrication chamber containing a first bearing supported by the first bearing support and a second bearing supported by the second bearing support, and an oil supply circuit for the enclosure; • The module further includes an annular sealing skirt extending around the retaining ring and the first and second flanges. This skirt comprises a first axial end sealed against the first bearing support and a second axial end sealed against the second bearing support. The skirt is made of a deformable material and is designed to provide a seal around the flanges, between the first and second bearing supports, in the event of shear bolt failure. Although the skirt provides a seal around the flanges, this sealing is not necessarily required by default, as the flanges may be equipped with their own sealing system. In the event of shear bolt failure, the skirt provides a seal around the flanges and is deformable to absorb the relative movements between the bearing supports. Therefore, there is no risk of oil leakage into the engine, as the oil remains contained by the skirt. • the skirt is made of elastically deformable material;

[0020] — the skirt is made of elastomer; • the first end of the skirt is crossed by the screws for fixing the ring to the first bearing support; • the first end of the skirt is fixed to the annular rib of the first bearing support; • the first end of the skirt is oriented radially inwards so that a free peripheral edge of this end is oriented radially inwards; • the first end of the skirt is sandwiched between the rib and the first end of the ring; • The module also includes an annular housing that extends around the axis, with the second bearing support being fixed to the housing.

[0021] — the second end of the skirt is fixed to the flange of the second bearing support;

[0022] — the second end of the skirt is radially clamped onto the flange by means of a hose clamp that surrounds the flange;

[0023] — the clamping collar comprises at least two angular sectors which are arranged end to end and which include at their ends lugs for fixing the sectors together, the lugs of two adjacent sectors being fixed together by fixing elements such as screws;

[0024] — the hose clamp is a perforated band clamp and includes a screw of which the Screwing and unscrewing allows adjustment of the internal diameter of the collar;

[0025] — the flange of the second bearing support is axially interposed between the flange of the first bearing support and the other flange of the casing;

[0026] — the flange of the second bearing support is fixed to the flange of the housing by screws non-fusible;

[0027] — the skirt has a generally domed shape with a concavity oriented radially towards inside, when the fusible screws are not broken;

[0028] — the skirt defines a free annular cavity around at least part of the first bearing support and / or second bearing support;

[0029] — the skirt is loaded with fibres;

[0030] — the fibers are oriented in the axial direction, which allows the skirt to have a bending deformation capacity and tensile hardness.

[0031] The present invention also relates to an aircraft turbomachine, comprising at least one module as described above. Brief description of the figures

[0032] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which:

[0033] [Fig-1] [Fig.1] is a schematic half-view in axial section of a part of a aircraft turbomachine,

[0034] [Fig.2] [Fig.2] is a partial schematic axial cross-sectional view of a bearing lubrication chamber,

[0035] [Fig.3] [Fig.3] is a larger-scale view of part of [Fig.2] and shows a decoupling device comprising fusible screws, which are here unbroken.

[0036] [Fig.4] [Fig.4] is a view similar to that of [Fig.3] and shows the decoupling device with fusible screws here broken,

[0037] [Fig.5] [Fig.5] is a schematic axial cross-sectional view of a module according to an embodiment of the invention,

[0038] [Fig. 6a-6b] Figures 6a and 6b are larger-scale views of details of the [Fig. 5] and respectively show axial ends of a module retaining ring,

[0039] [Fig.7] [Fig.7] is a view similar to that of [Fig.5] and shows the module in case of breakage of the fusible screws,

[0040] [Fig.8] [Fig.8] is a schematic perspective view of a clamp for securing one of the axial ends of a sealing skirt; and

[0041] [Fig. 9a-9b] Figures 9a and 9b are schematic views of another necklace of clamping for fixing one of the axial ends of the sealing skirt. Detailed description of the invention

[0042] Fig. 1 shows a turbomachine 10 for an aircraft, this turbomachine 10 being here a twin-spool turbojet.

[0043] Axis A designates the longitudinal axis of the turbomachine.

[0044] The turbomachine 10 comprises a gas generator 12 which includes, from upstream to downstream with reference to the gas flow along axis A, a low-pressure (LP) compressor 14, a high-pressure (HP) compressor, an annular combustion chamber, a high-pressure (HP) turbine, and a low-pressure (LP) turbine. The turbomachine 10 is partially shown, and only the LP compressor 14 is depicted in the drawing.

[0045] Although not visible in [Fig.1], the HP compressor rotor is connected to the HP turbine rotor by a high-pressure shaft, and the LP compressor rotor 14 is connected to the LP turbine rotor by a low-pressure shaft which passes through the high-pressure shaft and drives a propulsion propeller, called a blower 16, located upstream of the gas generator 12 and which is surrounded by an annular casing called a blower casing 18.

[0046] The blower housing 18 is connected to the gas generator 12 by an intermediate housing 20 which includes a central hub 22 and a series of radial arms 24 connecting the hub 22 to the blower housing 18.

[0047] The gas generator 12 defines a main annular flow channel V1 of a first air flow, called primary flow FL. The gas generator 12 is surrounded by a secondary annular flow channel V2 of a second air flow, called secondary flow F2.

[0048] The airflow F entering the blower 16 splits into a portion forming the primary flow FL. The air in this primary flow FL is compressed in the BP 14 and HP compressors, then mixed with fuel and burned in the combustion chamber. The combustion gases of the primary flow are then expanded in the HP and BP turbines and finally flow through an exhaust nozzle.

[0049] The other part of the airflow entering the blower 16 forms the secondary flow F2 and is intended to be mixed with the primary flow Fl downstream of the nozzle.

[0050] Fig. 1 further shows a module 30 of the turbomachine, this module 30 comprising annular bearing supports 32, 34, an annular housing 36, a lubrication chamber 38 and an oil supply circuit 40 for the chamber 38.

[0051] A first annular bearing support 32 extends around the axis A and includes a first annular fixing flange 32a, more clearly visible in [Fig.2].

[0052] A second annular bearing support 34 extends around the axis A and includes a second annular fixing flange 34a. The flanges 32a, 34a extend radially outwards and are suitable for being applied axially against each other and fixed together by screws 42 which are shear-off and more clearly visible in figures 2 to 4.

[0053] An annular housing 36 extends around axis A, and the second bearing support 34 is fixed to this housing 36 by screws that are not shear-resistant and are not shown in the drawings. The shear-resistant and non-shear-resistant screws 42 may be located on the same circumference centered on axis A. The housing 36 may be the intermediate housing 20 of [Fig. 1] or another housing fixed to or integral with this intermediate housing 20.

[0054] The housing 36 includes a flange 36a onto which the flange 34a is applied and fixed by the aforementioned non-sheathable screws. The flange 34a of the second bearing support 34 is axially interposed between the flange 32a of the first bearing support 32 and the flange 36a of the housing 36, as illustrated in Figures 2 to 4.

[0055] The lubrication enclosure 38 is at least partly delimited by the first bearing support 32 and contains a first bearing 44, or upstream bearing, carried by the first bearing support 32, and a second bearing 46, or downstream bearing, carried by the second bearing support 34.

[0056] In the example shown, the upstream bearing 44 is a roller bearing and the downstream bearing 46 is a ball bearing.

[0057] Furthermore, in the example shown, the first bearing support 32 has a generally annular and elongated shape along the axis A, and comprises an upstream end carrying the rolling bearing 44, and a downstream end connected to the flange 32a. The second bearing support 34 has a generally annular and radial shape, and comprises a radially internal end carrying the downstream bearing 46, and a radially external end connected to the flange 34a.

[0058] The oil supply circuit 40 of the enclosure 38 is more clearly visible in [Fig.2] and includes an oil distributor 48 and at least one oil line 50. The oil distributor 48 is integral with the housing 36 and includes at least one oil inlet 48a and at least one first oil outlet 48b.

[0059] The oil inlet 48a is suitable for connection to an oil reservoir not shown.

[0060] The oil line 50 is integral with the first bearing support 32 and has an end 40a, here downstream, connected to the first oil outlet 48b of the distributor 48 for the purpose of circulating oil from said inlet 48a to said at least one outlet 48b.

[0061] In the example shown, the distributor 48 comprises two oil outlets 48b, 48c, the first oil outlet 48b mentioned above and a second oil outlet 48c. The second oil outlet 48c can be connected to another line or to an oil nozzle 52 as illustrated in the drawing. The nozzle 52 sprays oil onto the downstream bearing 46, while the line 50 connected to the first outlet 48b of the distributor 48 supplies oil to the upstream bearing 44 for lubrication.

[0062] Preferably, the first outlet 48b is oriented axially, in particular towards the first bearing support 32, i.e. here upstream. The second outlet 48c can be oriented radially inwards.

[0063] In figures 2 to 4, it can also be seen that the conduit 50 includes a part which extends axially and which passes through an axial orifice 54 of the second bearing support 34. The conduit 50 is radially interposed between the downstream bearing 46 and the flanges 32a, 34a of the bearing supports 32, 34.

[0064] Fig. 3 shows the default and normal operating case in which the flanges 32a of the bearing supports 32 are applied axially to each other and fixed together by the shear screws 42.

[0065] As mentioned above, in the event of imbalance and vibrations, the shear screws 42 are liable to break as illustrated in [Fig. 4]. The flange 32a of the first bearing support 32, and in particular the first bearing support 32 as a whole, is then no longer axially restrained and moves axially away from the second bearing support 32. The first bearing support 32 then moves upstream, creating an annular passage 56 between the flanges 32a, 34a of the bearing supports 32, 34.

[0066] The oil supplied by the distributor 48 continues to flow into the enclosure and accumulates there. This oil is then liable to flow by gravity through the passage 56 and can reach the primary vein VI, which is problematic as mentioned above.

[0067] Furthermore, pieces of the broken fusible screws 42 are likely to detach in particular from the flange 32a and pass into the sub-ventilation of the motor which surrounds the lubrication chamber 38 and it is important to prevent the screws from causing damage.

[0068] The present invention offers a simple, effective and economical solution to at least this last problem.

[0069] As can be seen in figures 5 to 7, one of the bearing supports 32 carries a retaining ring 86 which extends around this bearing support 32 and at least partly around the shear screws 42.

[0070] The retaining ring 86 is suitable for retaining at least part of the shear screws 42 in the event of breakage of the shear screws 42, and in particular the broken pieces of screw located on the side of the bearing support 32 and the retaining ring 86.

[0071] The retaining ring 86 can be formed from a sheet metal, as in the example shown.

[0072] In this example, the retaining ring 86 comprises a first axial end 86a fixed to the bearing support 32 which carries it, and a second opposite axial end 86b which is free and which is located at a radial distance from this bearing support 32.

[0073] The first end 86a of the ring 86 can be fixed to the bearing support 32 by axial screws 87 which pass through holes in this first end 86a and in the bearing support 32. The first end 86a of the ring 86 is here fixed to a annular rib 84 of the first bearing support 32, this rib 84 extending radially outwards.

[0074] The first end 86a of the ring 86 can be oriented radially inwards so that a free peripheral edge 86al of this end 86a is oriented radially inwards.

[0075] The retaining ring 86 has for example a general L-shaped form and comprises a first radial wall 87a connected to the bearing support 32 which carries it, and a second cylindrical wall 87b which extends axially from the outer periphery of the first wall 87a and around at least part of the shear screws 42.

[0076] As mentioned above, the module according to the invention may further include a lubrication chamber 38.

[0077] Preferably, the invention further proposes to provide a solution for containing the oil inside the enclosure 38, even when the screws 42 break and the bearing supports 32, 34 move axially apart from each other.

[0078] As illustrated in Figures 5 and 7 also, the invention thus proposes an annular sealing skirt 80 which extends around the retaining ring 86 and the flanges 32a, 34a and which comprises a first axial end 80a fixed in a sealed manner to the first bearing support 32 and a second axial end 80b fixed in a sealed manner to the second bearing support 34.

[0079] The skirt 80 is made of a deformable material, preferably elastically deformable such as an elastomer. The skirt 80 is, for example, made of Viton®.

[0080] The skirt 80 is preferably fiber-reinforced. The fibers are preferably oriented in the axial direction so that the skirt 80 has a bending deformation capacity and a tensile strength.

[0081] The skirt 80 is suitable for ensuring a seal around the flanges 32a, 34a, between the first and second bearing supports 32, 34 in particular in the event of breakage of the shear screws 42 ([Fig.7]).

[0082] In the example shown, the skirt 80 has a generally domed shape with a concavity oriented radially inwards when the fusible screws 42 are not broken ([Fig. 5]). The skirt 80 can define a free annular cavity 82 around at least part of the bearing support 32 and / or the bearing support 34.

[0083] In the example shown, the first end 80a of the skirt 80 is fixed to the annular rib 84 of the first bearing support 32. This rib 84 extends radially outwards, here at an axial distance from the flange 32a.

[0084] The first end 80a of the skirt 80 can be oriented radially inwards so that a free peripheral edge 80al of this end 80a is oriented radially inwards.

[0085] The first end 80a of the skirt 80 is axially intercalated between the rib 84 and the first end 86a of the retaining ring 86, which thus forms a plywood.

[0086] The first end 80a of the skirt 80 is preferably crossed by the screws 87 for fixing the ring 86 to the first bearing support 32.

[0087] In the example shown, the second end 80b of the skirt 80 is fixed to the flange 34a of the second bearing support 34.

[0088] The second end 80b of the skirt 80 can be radially clamped onto the flange 34a by means of a clamping collar 88 which surrounds the flange 34a.

[0089] In the embodiment of [Fig. 8], the clamping collar 88 comprises at least two angular sectors 88a, 88b arranged end to end and comprising at their ends lugs 90 for securing the sectors 88a, 88b to each other. The lugs 90 of two adjacent sectors 88a, 88b are secured to each other by fasteners such as screws 92 that pass through holes in the lugs 90, for example.

[0090] In the embodiment variant of figures 9a and 9b, the clamping collar 88 is a collar with an openwork band and includes a screw 94 whose screwing-unscrewing allows adjustment of the internal diameter of the collar 88.

[0091] In normal operation, the skirt 80 is in the configuration shown in [Fig. 5] and is not functional. It is in standby mode. When the screws 42 break and the bearing support 32 moves axially away from the bearing support 34, the skirt 80 is in the configuration shown in [Fig. 7] and is functional. The skirt 80 then provides a seal between the flanges 32a and 34a, and any oil that might pass through the passage 56 between the flanges 32a and 34a is retained by the skirt 80 and does not escape from the housing 38. Furthermore, the retaining ring 86 retains any fragments of the shear screws that detach from the flange 32a ([Fig. 5]). These pieces are likely to come into contact with the skirt 80 and damage it, therefore the retaining ring 86 also provides protection for the skirt 80 when it is associated with a skirt as in the example shown.

Claims

Demands

1. Module (30) for an aircraft turbomachine (10), this module (30) comprising: - a first annular bearing support (32) extending around an axis (A) and comprising a first annular fixing flange (32a), - a second annular bearing support (34) extending around the axis (A) and comprising a second annular fixing flange (34a), the first and second flanges (32a, 34a) being able to be applied axially against each other and to be fixed together by shear screws (42), characterized in that one of the bearing supports (32) carries a retaining ring (86) extending around this bearing support (32) and at least partly around the shear screws (42), and which is able to retain at least part of these shear screws (42) in the event of breakage of the shear screws (42).

2. Module (30) according to claim 1, wherein the retaining ring (86) is formed by a sheet.

3. Module according to claim 1 or 2, wherein the retaining ring (86) comprises a first axial end (86a) fixed to the bearing support (32) which carries it, and a second opposite axial end (86b) which is free and is located at a radial distance from this bearing support (32).

4. Module (30) according to claim 3, wherein the first end (86a) of the ring (86) is fixed to the bearing support (32) by axial screws (87) which pass through holes in this first end (86a) and in the bearing support (32).

5. Module (30) according to claim 3 or 4, wherein the first end (86a) of the ring (86) is fixed to an annular rib (84) of the first bearing support (32), this rib (84) extending radially outwards.

6. Module (30) according to claim 5, wherein the first end (86a) of the ring (86) is oriented radially inwards such that a free peripheral edge (86al) of this end (86a) is oriented radially inwards.

7. Module according to any one of the preceding claims, wherein the retaining ring (86) has a generally L-shaped form and comprises a first radial wall (87a) connected to the bearing support (32) which carries it, and a second cylindrical wall (87b) which extends axially from the outer periphery of the first wall (87a) and around at least part of the fusible screws (42).

8. Module according to any one of the preceding claims, wherein it further comprises a lubrication enclosure (38) which is at least partly delimited by the first bearing support (32), this lubrication enclosure (38) containing a first bearing support (44) carried by the first bearing support (32) and a second bearing support (46) carried by the second bearing support (34), and an oil supply circuit (40) for the enclosure (38).

9. Module according to any one of the preceding claims, wherein it further comprises an annular sealing skirt (80) which extends around the retaining ring (86) and the first and second flanges (32a, 34a) and which comprises a first axial end (80a) fixed in a hermetic manner to the first bearing support (32) and a second axial end (80b) fixed in a hermetic manner to the second bearing support (34), this skirt (80) being made of a deformable material and being capable of ensuring a seal around the flanges (32a, 34a), between the first and second bearing supports (32, 34) in the event of failure of the shear screws (42).

10. Module according to claim 9, wherein the skirt (80) is made of elastically deformable material.

11. Module (30) according to claim 9 or 10, depending on claim 4, wherein the first end (80a) of the skirt (80) is passed through by the screws (87) for fixing the ring (86) to the first bearing support (32).

12. Module (30) according to claim 9 or 10, depending on claim 5 or 6, wherein the first end (80a) of the skirt (80) is fixed to the annular rib (84) of the first bearing support (32).

13. Module (30) according to claim 12, wherein the first end (80a) of the skirt (80) is oriented radially inwards such that a free peripheral edge (80al) of this end (80a) is oriented radially inwards.

14. Module (30) according to claim 12 or 13, wherein the first end (80a) of the skirt (80) is intercalated between the rib (84) and the first end (86a) of the ring (86).

15. 13 Module (30) according to any one of the preceding claims, wherein it further comprises an annular housing (36) which extends around the axis (A), the second bearing support (34) being fixed to the housing (36).

16. Turbomachine (10) for an aircraft, comprising at least one module (30) according to any one of the preceding claims.

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