MODULE FOR AN AIRCRAFT TURBOMACHINE
An expandable annular seal between bearing flanges in an aircraft turbomachine prevents oil leakage by maintaining a seal during shear screw failure, addressing the contamination risk and ensuring clean air supply.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- SAFRAN AIRCRAFT ENGINES SAS
- Filing Date
- 2024-05-24
- Publication Date
- 2026-06-12
AI Technical Summary
The risk of oil leakage into the primary channel due to the decoupling of bearing supports in an aircraft turbomachine, leading to contamination of the engine and potential supply of polluted air to the aircraft, is not adequately addressed by existing shear screw decoupling devices.
An expandable annular seal is interposed between the bearing flanges, which maintains a seal when the shear screws break, preventing oil leakage by expanding to contain the oil within the lubrication enclosure.
The expandable seal effectively prevents oil leakage, ensuring that oil remains contained within the lubrication chamber even when the bearing supports separate, thereby avoiding engine contamination and ensuring clean air supply to the aircraft.
Smart Images
Figure 00000011_0000 
Figure 00000012_0000 
Figure 00000012_0001
Abstract
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 significant 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 flanges of the bearing supports, 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] The invention relates to a technical solution aimed at eliminating the risk of oil leakage into the primary channel after decoupling the bearing supports from the lubrication chamber. Summary of the invention
[0013] The invention relates to a module for an aircraft turbomachine, this module comprising:
[0014] - a first annular bearing support which extends around an axis and which comprises a first annular fixing flange,
[0015] - 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 to be applied axially against each other and to be fixed together by shear screws,
[0016] - an annular housing that extends around the axis, the second bearing support being fixed to the crankcase,
[0017] - a lubrication chamber which is at least partly delimited by the first bearing support, this lubrication enclosure containing a first bearing supported by the first bearing support and a second bearing supported by the second bearing support, and
[0018] - an oil supply circuit for the enclosure, and
[0019] - an expandable annular joint interposed axially between the first and second flanges, this seal being axially compressed between the first and second flanges when the fusible screws are unbroken and the first and second flanges are applied axially to each other, and being capable of being axially expanded when the fusible screws are broken and the first and second flanges are axially separated from each other, the seal maintaining an axial seal between the flanges when in the expanded state.
[0020] Under normal operating conditions, the shear screws ensure 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. The seal then expands and provides a seal at the flanges. Therefore, there is no risk of oil leakage into the engine's oil passage because the oil remains contained within the housing by the expanded seal.
[0021] The module according to the invention may comprise one or more of the following features, taken individually or in combination with each other: • the joint is of the accordion or bellows type; • the joint is a folded or corrugated blade; • the seal is made of metal or elastomer, preferably filled; • the seal has a first axial end fixed to the flange of the first bearing support, and a second axial end opposite the first axial end and fixed to the flange of the second bearing support; • the first and second axial ends of the joint are glued to the flanges; • In its expanded state, the joint has an axial length or dimension that represents at least twice its length or axial dimension in the compressed state; • in the expanded state, the joint has an axial length or dimension that represents at least three times its axial length or dimension in the compressed state; • the flange of the second bearing support is axially interposed between the flange of the first bearing support and another flange of the housing; • the flange of the second bearing support is fixed to the flange of the housing by non-shear screws.
[0022] The present invention also relates to an aircraft turbomachine, comprising at least one module as described above. Brief description of the figures
[0023] 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:
[0024] [Fig-1] [Fig.1] is a schematic half-view in axial section of a part of a aircraft turbomachine,
[0025] [Fig.2] [Fig.2] is a partial schematic axial cross-sectional view of a bearing lubrication chamber,
[0026] [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,
[0027] [Fig.4] [Fig.4] is a view similar to that of [Fig.3] and shows the decoupling device with fusible screws here broken,
[0028] [Fig. 5] [Fig. 5] is a schematic axial cross-sectional view of an expandable seal, and illustrates one embodiment of the invention,
[0029] [Fig.6] [Fig.6] is a view similar to that of [Fig.5] and shows the expanded sealing gasket after the fuse screws have broken. Detailed description of the invention
[0030] Fig. 1 shows a turbomachine 10 for an aircraft, this turbomachine 10 being here a twin-spool turbojet.
[0031] Axis A designates the longitudinal axis of the turbomachine.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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].
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] In the example shown, the upstream bearing 44 is a roller bearing and the downstream bearing 46 is a ball bearing.
[0045] 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.
[0046] 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.
[0047] The oil inlet 48a is suitable for connection to an oil reservoir not shown.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] Figures 2 to 4 further show that the conduit 50 includes a portion 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.
[0052] 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.
[0053] 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.
[0054] 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.
[0055] The present invention offers a simple, effective and economical solution to this problem.
[0056] The invention proposes to provide a solution for containing the oil inside the enclosure, even when the screws 42 break and the bearing supports 32, 34 move axially apart from each other.
[0057] As illustrated in figures 5 and 6, the invention thus proposes an expandable annular seal 80 interposed axially between the flanges 32a, 34a.
[0058] The seal 80 is axially compressed between the flanges 32a, 34a when the fusible screws 42 are unbroken and when the flanges 32a, 34a are applied axially to each other (cf. [Fig.5]).
[0059] The seal 80 is expanded axially when the fusible screws 42 are broken and the flanges 32a, 34a are moved axially apart from each other (cf. [Fig.6]).
[0060] The special feature of the seal 80 is that it maintains an axial seal between the flanges 32a, 34a when it is in its expanded state. The seal 80 can also be designed to provide this seal when it is in its compressed state.
[0061] As in the example shown in the drawings, the seal 80 can be mounted between two radial faces 82, 84 opposite the flanges 32a, 34a, and in particular in respective housings 82a, 84a of these faces 82, 84.
[0062] The joint 80 can be of the accordion or bellows type.
[0063] The joint 80 can be a bent or corrugated blade.
[0064] The seal 80 can be made of metal or elastomer, preferably filled. The seal 80 is for example in fiber-reinforced Viton®.
[0065] The seal 80 may have a first axial end 80a fixed to the flange 32a of the bearing support 32, and a second axial end 80b opposite the first axial end 80a and fixed to the flange 34a of the bearing support 34. The first and second axial ends 80a, 80b of the seal 80 are preferably bonded to the flanges 32a, 32b.
[0066] In its expanded state, the seal 80 has a length L1 or axial dimension which is at least twice, and preferably at least three times, its length L2 or axial dimension in the compressed state (Figures 5 and 6). The length L1 may be less than four or even five times the length L2.
[0067] In normal operation, the seal 80 is in the configuration of [Fig. 5] and is compressed between the flanges 32a, 34a to ensure or not a seal between these flanges. When the screws 42 break and the bearing support 32 moves axially away from the Bearing support 34, the seal 80 expands while remaining axially supported and even attached to the flanges 32a, 34a, thus ensuring a seal between the flanges 32a, 34a. Any oil that might pass through the passage 56 between the flanges 32a, 34a is then retained by the seal 80 and does not escape from the housing 38.
Claims
Demands
1. A module (30) for an aircraft turbomachine (10), said 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), - an annular housing (36) extending about the axis (A), the second bearing support (34) being fixed to the housing (36), - a lubrication chamber (38) which is at least partially delimited by the first bearing support (32), this lubrication chamber (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),- an oil supply circuit (40) for the enclosure (38), and - an expandable annular seal (80) axially interposed between the first and second flanges (32a, 34a), this seal (80) being axially compressed between the first and second flanges (32a, 34a) when the shear screws (42) are unbroken and the first and second flanges (32a, 34a) are axially pressed against each other, and being capable of axial expansion when the shear screws (42) are broken and the first and second flanges (32a, 34a) are axially separated from each other, the seal (80) maintaining an axial seal between the flanges (32a, 32b) when in the expanded state.
2. Module (30) according to claim 1, wherein the joint (80) is of the accordion or bellows type.
3. Module (30) according to claim 1 or 2, wherein the joint (80) is a bent or corrugated blade.
4. Module (30) according to any one of the preceding claims, wherein the seal (80) is made of metal or elastomer, preferably filled.
5. Module (30) according to any one of the preceding claims, wherein the joint (80) has a first axial end (80a) fixed to the flange (32a) of the first bearing support (32), and a second axial end (80b) opposite the first axial end (80a) and fixed to the flange (34a) of the second bearing support (34).
6. Module (30) according to claim 5, wherein the first and second axial ends (80a, 80b) of the joint (80) are bonded to the flanges (32a, 32b).
7. Module (30) according to any one of the preceding claims, wherein, in the expanded state, the joint (80) has a length (L1) or axial dimension that represents at least twice its length (L2) or axial dimension in the compressed state.
8. Module (30) according to claim 7, wherein, in the expanded state, the joint (80) has a length (L1) or axial dimension which is at least three times its length (L2) or axial dimension in the compressed state.
9. Module (30) according to any one of the preceding claims, wherein the flange (34a) of the second bearing support (34) is axially interposed between the flange (32a) of the first bearing support (32) and another flange (36a) of the housing (36).
10. Module (30) according to any one of the preceding claims, wherein the flange (34a) of the second bearing support (34) is fixed to a flange (36a) of the housing (36) by non-fusible screws.
11. Turbomachine (10) for an aircraft, comprising at least one module (30) according to any one of the preceding claims.