Module for an aircraft turbine engine with a circuit for supplying oil to the lubrication chamber

Abstract

The invention relates to a module (30) for an aircraft turbine engine (10), this module (30) comprising: - a lubrication chamber (38) which is at least partly delimited by bearing supports (32, 34) comprising flanges (32a, 34a) which are pressed axially against one another and attached to one another by shear bolts (42); and - an expandable annular seal (80) which is inserted axially between the flanges (32a, 34a).

Description

[0001]DESCRIPTION 1 TITLE: MODULE FOR AN AIRCRAFT TURBOMACHINE Technical Field of the Invention The present invention relates to a module for an aircraft turbomachine, as well as a turbomachine comprising such a module. Technical Background The prior art includes, in particular, documents EP-B1-2721260, EP-B1-2071141, EP-B1-2721260, FR-A1-2888621, EP-A1-1496294 and US-A1-20111 / 236205. An aircraft turbomachine comprises a gas generator which conventionally includes, from upstream to downstream, with reference to the gas flow in the turbomachine, at least one compressor, an annular combustion chamber and at least one turbine. In the case of a twin-spool turbojet engine, with low-pressure and high-pressure sections 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.of a gas flow, called the primary flow, which passes through the compressors, the combustion chamber, and the turbines. 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 that passes through the high-pressure shaft and drives the shaft of a propulsion propeller, generally located upstream of the gas generator. When this propeller is enclosed and thus surrounded by an annular casing, it is called a fan and generates an airflow, called the secondary flow, which flows around the gas generator. The propeller shaft and the low-pressure shaft are guided by bearings housed in a lubrication chamber. This chamber is surrounded by the first channel and is at least partially delimited by bearing supports. A first roller bearing located upstream isThe first bearing 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 on a stator housing. The lubrication chamber is designed to lubricate the bearings and maintain an oily atmosphere around them. Oil is supplied to the chamber via a supply circuit. 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 significant risk of damage. To limit the forces transmitted to the stator in the presence of a large imbalance, a shear screw decoupling device is described in document FR-A1-2831624.In practice, the second bearing support is fixed to the stator housing by non-felt mounting 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 "felt" screws, whose operation is fully described in the aforementioned document, have a reduced cross-sectional area that can break beyond a predetermined tensile force, thus decoupling 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. This phenomenon is problematic because the enclosure continuesto be supplied with oil by the aforementioned circuit, and the oil that accumulates in the enclosure is liable 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 pollution. This oil can reach the first intake duct from which air is drawn for supplying 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 fumes and unpleasant odors. The invention relates to a technical solution 3 aimed at eliminating the risk of oil leakage into the primary intake duct after decoupling the bearing supports from the lubrication enclosure. Summary of the invention: The invention relates to a module for an aircraft turbomachine, this module comprising: - a first annular bearing support extending around an axis and comprising a first- an annular mounting flange, - a second annular bearing support extending around the axis and comprising a second annular mounting flange, the first and second flanges being capable of being axially pressed against each other and secured together by shear bolts, - an annular housing extending around the axis, the second bearing support being fixed to the housing, - a lubrication chamber 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 chamber, and - an expanding annular seal interposed axially between the first and second flanges, this seal being axially compressed between the first and second flanges when the shear bolts are intact and the first and second flanges areapplied axially to one another, and capable of axial expansion when the shear screws break and the first and second flanges are axially separated from each other, the seal maintains an axial seal between the flanges when in its expanded state. In normal operation, the shear screws ensure the axial retention of the first bearing support vis-à-vis the second bearing support. In the event of shear screw failure, the bearing supports separate and move axially apart from each other. The seal then expands and provides a seal at the flanges. There is therefore no risk of oil leakage into the engine's oil passage because the oil remains contained within the housing by the expanded seal. The module according to the invention may include one or more of the following features, taken individually or in combination: the seal is of the accordion or bellows type; the joint isa 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 seal are bonded to the flanges; in its expanded state, the seal has an axial length or dimension that is at least twice its axial length or dimension in its compressed state; in its expanded state, the seal has an axial length or dimension that is at least three times its axial length or dimension in its 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(s) of the housing by non-shear bolts. The present invention also relates to an aircraft turbomachine, comprisingat least one module as described above. Brief Description of the Figures Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for which reference should be made to the accompanying drawings in which: [Fig. 1] Figure 1 is a schematic half-view in axial section of a part of an aircraft turbomachine, [Fig. 2] Figure 2 is a schematic partial view in axial section of a bearing lubrication chamber, [Fig. 3] Figure 3 is a larger-scale view of a part of Figure 2 and shows a decoupling device comprising shear screws, here shown unbroken, [Fig. 4] Figure 4 is a view similar to that of Figure 3 and shows the decoupling device with shear screws, here shown broken, [Fig. 5] Figure 5 is a schematic axial section of an expanding seal, and illustrates an embodiment of the invention, [Fig. 6] Figure 6 is a viewsimilar to that of Figure 5 and shows the expanded sealing gasket after the shear screws have broken. Detailed description of the invention Figure 1 shows a turbomachine 10 for an aircraft, this turbomachine 10 being a twin-spool, turbofan engine. Axis A designates the longitudinal axis of the turbomachine. 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. Although not visible in Figure 1, the rotor of the HP compressor is connected to the rotor of the HP turbine by a high-pressure shaft, and the rotor of the LP compressor 14 is connected to the rotor of the LP turbine by a low-pressure shaft.Pressure flows through the high-pressure shaft and rotates a propulsion propeller, called a fan 16, located upstream of the gas generator 12 and surrounded by an annular casing called the fan casing 18. The fan casing 18 is connected to the gas generator 12 by an intermediate casing 20, which includes a central hub 22 and a series of radial arms 24 connecting the hub 22 to the fan casing 18. The gas generator 12 defines a primary annular flow channel V1 for the first airflow, called the primary flow F1. The gas generator 12 is surrounded by a secondary annular flow channel V2 for the second airflow, called the secondary flow F2. The airflow F entering the fan 16 splits into a portion forming the primary flow F1. The air from this primary stream F1 is compressed in the BP 14 and HP compressors, then mixed with fuel and burned in the combustion chamber. The combustion gases from the primary streamThe air is then expanded in the HP and LP turbines and finally flows into an exhaust nozzle. The remaining portion of the airflow entering the fan 16 forms the secondary flow F2 and is intended to be mixed with the primary flow F1 downstream of the nozzle. Figure 1 further shows a turbomachine module 30, 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. A first annular bearing support 32 extends around the axis A and includes a first annular mounting flange 32a, more clearly visible in Figure 2. A second annular bearing support 34 extends around the axis A and includes a second annular mounting 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 fusible and more clearly visible in figures 24. An annular housing 36 extends around axis A, and the second bearing support 34 is fixed to this housing 36 by screws that are non-consumable and are not shown in the drawings. The consumable and non-consumable screws 42 may be located on the same circumference centered on axis A. The housing 36 may be the intermediate housing 20 of Figure 1 or another housing fixed to or integral with this intermediate housing 20. The housing 36 includes a flange 36a onto which the flange 34a is applied and fixed by the aforementioned non-consumable 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. The lubrication chamber 38 is at least partially 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 bearingdownstream, supported by the second bearing support 34. In the example shown, the upstream bearing 44 is a roller bearing and the downstream bearing 46 is a ball bearing. Furthermore, in the example shown, the first bearing support 32 has a generally annular shape and is elongated along axis A, and comprises an upstream end carrying the roller bearing 44, and a downstream end connected to 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 flange 34a. The oil supply circuit 40 for enclosure 738 is more clearly visible in Figure 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. The oil inlet 48a is suitable for connection to an oil reservoir.The oil line 50 is integral with the first bearing support 32 and has a downstream end 40a connected to the first oil outlet 48b of the distributor 48 for the circulation of oil from said inlet 48a to said at least one outlet 48b. In the example shown, the distributor 48 comprises two oil outlets 48b, 48c, the aforementioned first oil outlet 48b, 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 its lubrication. Preferably, the first outlet 48b is oriented axially, specifically towards the first bearing support 32, i.e., upstream in this case. The second outlet 48c can be oriented radially inwards.Figures 2 to 4 further show that the conduit 50 includes a portion extending axially through an axial opening 54 in 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. Figure 3 shows the default configuration and normal operating conditions in which the flanges 32a of the bearing supports 32 are axially pressed against each other and fastened together by shear screws 42. As mentioned above, in the event of imbalance and vibration, the shear screws 42 are liable to break, as illustrated in Figure 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 theBearing supports 32, 34. The oil supplied by the distributor 48 continues to flow into the housing and accumulates there. This oil can then flow by gravity through the passage 56 and reach the primary vein V1, which is problematic as mentioned above. The present invention proposes a simple, effective, and economical solution to this problem. The invention proposes a solution to contain the oil inside the housing, even when the screws 42 break and the bearing supports 32, 34 move axially apart. As illustrated in Figures 5 and 6, the invention thus proposes an expandable annular seal 80 interposed axially between the flanges 32a, 34a. The seal 80 is axially compressed between the flanges 32a, 34a when the shear screws 42 are unbroken and when the flanges 32a, 34a are axially pressed against each other (see Figure 5). The seal 80 is axially expanded when the shear screws42 are broken and the flanges 32a, 34a are axially separated from each other (see Figure 6). The special feature of the seal 80 is that it maintains an axial seal between the flanges 32a, 34a when in its expanded state. The seal 80 can also be designed to provide this seal when in its compressed state. 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 recesses 82a, 84a of these faces 82, 84. The seal 80 can be of the accordion or bellows type. The seal 80 can be a folded or corrugated blade. The seal 80 can be made of metal or elastomer, preferably reinforced. The seal 80 is, for example, made of fiber-reinforced Viton®. 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 supportof bearing 34. The first and second axial ends 80a, 80b of the seal 80 are preferably bonded to the flanges 32a, 32b. In its expanded state, the seal 80 has a length L1 or axial dimension that is at least twice, and preferably at least three times, its length L2 or axial dimension in its compressed state (Figures 5 and 6). The length L1 may be less than four or even five times the length L2. In normal operation, the seal 80 is in the configuration shown in Figure 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, or even while remaining attached to the flanges 32a, 34a, thus ensuring a seal between the flanges 32a, 34a. Any oil that might pass through the opening 56 between the flanges 32a, 34a is then retained by the seal 80 and does notdoes not escape from enclosure 38.

Claims

CLAIMS 1. 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 axially pressed against each other and 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 (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 axially expanded 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 seal (80) is of the accordion or bellows type.

3. Module (30) according to claim 1 or 2, wherein the seal (80) is a folded 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 loaded.

5. Module (30) according to any one of the preceding claims, wherein the seal (80) comprises 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 seal (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 seal (80) has a length (L1) or axial dimension that is 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 seal (80) has a length (L1) or axial dimension that 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-shear bolts.

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

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