MODULE FOR AN AIRCRAFT TURBOMACHINE

Abstract

Module (30) for an aircraft turbomachine (10), this module (30) comprising: - a lubrication chamber (38) which is at least partially delimited by bearing supports (32, 34), - an oil supply circuit (40) for the chamber (38), and - an annular sealing skirt (80) which includes a first axial end (80a) hermetically fixed to the first bearing support (32) and a second axial end (80b) hermetically fixed to the second bearing support (34), this skirt (80) being made of a deformable material and being capable of providing a seal around flanges (32a, 34a) of the bearing supports (32, 34), particularly in the event of failure of shear screws (42) securing these bearing supports (32, 34). 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] 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 a main axis and which includes a first annular fixing flange,

[0015] - a second annular bearing support which extends around the main axis and which includes a second annular fixing flange, the first and second flanges being suitable for being applied axially against each other and fixed together by shear screws,

[0016] - an annular housing that extends around the main 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 annular sealing skirt that extends around the first and second flanges and which comprises a first axial end fixed in a sealed manner to the first bearing support and a second axial end fixed in a sealed manner to the second bearing support, this skirt being made of a deformable material and being capable of ensuring a seal around the flanges, between the first and second bearing supports in particular in the event of breakage of the shear screws,

[0020] said second axial end of the skirt being fixed to the second bearing support by a fastening device comprising:

[0021] - at least one plywood extending circumferentially around the axis main and applied radially against the second axial end of the skirt,

[0022] - an annular plate fixed to the annular housing and extending radially towards the exterior relative to the main axis at the level of said at least one plywood, and

[0023] - clamping elements carried by the annular plate and capable of applying a clamping force in the radial direction on the plywood, each of these clamping elements being movable around a clamping axis parallel to said main axis, independently of each other, between a first non-clamping position in which it does not apply clamping force on the plywood, and a clamping position in which it applies said clamping force.

[0024] Under normal operating conditions, the shear screws ensure the axial retention of the first bearing support relative to the second bearing support. Although the skirt provides a seal around the flanges, this seal is not necessarily required at this stage because the flanges may be equipped with their own sealing system. If the shear screws break, the bearing supports separate and move axially apart. The skirt then 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 leaking into the engine's oil passage because the oil remains contained by the skirt.

[0025] Furthermore, the module is equipped with a particularly innovative skirt fastening device. Insofar as the environment around the skirt is Given the relatively limited space available, it is not always possible to incorporate a fastening system with elements oriented radially to the main axis. The invention proposes, on the contrary, the use of clamping elements that rotate around clamping axes parallel to the main axis, and are therefore axially oriented. This ensures optimal radial clamping of the skirt without the need for bulky and difficult-to-access radial elements.

[0026] The module according to the invention may comprise one or more of the following features, taken individually or in combination with each other: • the clamping elements are regularly distributed around said main axis; • the annular plate is fixed to the annular housing via at least one fluidic fitting of said circuit; • the fluidic fitting comprises a tubular sleeve oriented parallel to the main axis, and at least one external tab attached to the sleeve and extending in a radial plane to the main axis, the sleeve having a first end engaged in a housing of the annular casing and a second end, opposite to the first end, which is in fluidic communication with a pipe, said at least one tab having at least one orifice for the passage of a screw screwed into a hole in the annular casing; • the annular plate is axially interposed between said at least one leg and the annular housing; • the clamping elements are housed at least partially in at least one recess of said annular housing; • each of the clamping elements includes an eccentric and a screw for retaining the eccentric on the annular plate, the eccentric being movable around the screw which is centered on the clamping axis; • a plain bearing is mounted between the screw and the eccentric; • the plain bearing is formed by a cylindrical ring, one end of which includes an external annular rim, the ring being axially clamped by the screw against the annular plate and the annular rim being separated by an axial clearance from the eccentric; • the eccentric includes a recessed or projecting indentation suitable for cooperating with a tool for rotating the eccentric around its clamping axis; • the imprint is of the hexagonal or six-sided type; • The recess is raised and hollow to internally receive the screw and the said ring; • the eccentric has an external periphery comprising at least one cam surface, this cam surface possibly comprising at least one sharp edge forming a hard point when rotating the eccentric around its clamping axis; • the clamping device comprises several plywood pieces arranged one after the other around the main axis; • said at least one plywood comprises two cylindrical sectors of different diameters and connected together by a truncated conical sector; • the annular plate is not sectorized; • The annular plate is sectorized and comprises two sectors of 180° each ;

[0027] — the number of clamping elements is equal to the number of fusible screws in the module;

[0028] — the skirt is made of elastically deformable material;

[0029] — the skirt is made of elastomer;

[0030] — the first end of the skirt is fixed to an annular rib of the first bearing support, this rib extending radially outwards;

[0031] — the first end of the skirt is oriented radially outwards from so that a free peripheral edge of this end is oriented radially outwards;

[0032] — the first end of the skirt is pressed against an annular face of the rib thanks to an annular plywood;

[0033] — the plywood is fixed to the rib by screws that pass through holes in the rib, from the end of the skirt and the plywood;

[0034] — the second end of the skirt is fixed to the flange of the second bearing support;

[0035] — the flange of the second bearing support is axially interposed between the flange of the first bearing support and another flange of the casing;

[0036] — the flange of the second bearing support is fixed to the flange of the housing by screws non-fusible;

[0037] — the skirt has a generally curved shape with a concavity oriented radially towards inside, when the fusible screws are not broken;

[0038] — the skirt defines a free annular cavity around at least part of the first bearing support and / or second bearing support;

[0039] — the skirt is loaded with fibres;

[0040] — the fibers are oriented in the axial direction, which allows the skirt to have a bending deformation capacity and tensile hardness.

[0041] The present invention also relates to an aircraft turbomachine, comprising at least one module as described above. Brief description of the figures

[0042] 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:

[0043] [Fig-1] [Fig.1] is a schematic half-view in axial section of a part of a aircraft turbomachine,

[0044] [Fig.2] [Fig.2] is a partial schematic axial cross-sectional view of an enclosure bearing lubrication,

[0045] [Fig.3] [Fig.3] is a larger-scale view of part of [Fig.2] and shows a decoupling device with fusible screws, which are shown here unbroken.

[0046] [Fig.4] [Fig.4] is a view similar to that of [Fig.3] and shows the device of decoupling with fusible screws, which are broken here.

[0047] [Fig. 5] [Fig. 5] is a schematic axial cross-sectional view of a sealing skirt, and illustrates one embodiment of the invention,

[0048] [Fig.6] [Fig.6] is a view similar to that of [Fig.5] and shows the skirt sealing in case of breakage of the fusible screws,

[0049] [Fig.7] [Fig.7] is a schematic perspective view of a fastening device from one of the axial ends of the skirt;

[0050] [Fig.8] [Fig.8] is a schematic perspective and cross-sectional view of the device fixing of the [Fig.7], the cut being made at the level of a sleeve of a fluidic fitting;

[0051] [Fig.9] [Fig.9] is a schematic perspective and cross-sectional view of the device of fixing the [Fig.7], the cut being made at the level of a tab of the fluidic fitting;

[0052] [Fig. 10] [Fig. 10] is a schematic perspective and cross-sectional view of the fastening device of [Fig. 7], the section being made at the level of a clamping element;

[0053] [Fig. 11] [Fig. 11] is a schematic perspective, cross-sectional and larger scale view of the clamping element of [Fig. 10];

[0054] [Fig. 12] [Fig. 12] is a schematic perspective view of the fastening device of [Fig. 7], and shows an assembly step;

[0055] [Fig. 13] [Fig. 13] is a schematic perspective and cross-sectional view of the fastening device of [Fig. 7], and shows the assembly step;

[0056] [Fig. 14] [Fig. 14] is a schematic perspective view of the fastening device of [Fig. 7], and shows a tightening step;

[0057] [Fig. 15a-15c] Figures 15a to 15c are schematic front views of one of the clamping elements of the fastening device [Fig. 7], and shows several positions of this element around its clamping axis; and

[0058] [Fig. 16] The [Fig. 16] is a very schematic view of an alternative embodiment of the eccentric of the clamping element. Detailed description of the invention

[0059] Fig. 1 shows a turbomachine 10 for an aircraft, this turbomachine 10 being here a twin-spool turbojet.

[0060] Axis A designates the longitudinal axis of the turbomachine, also called the main axis.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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].

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] In the example shown, the upstream bearing 44 is a roller bearing and the downstream bearing 46 is a ball bearing.

[0074] 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.

[0075] 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.

[0076] The oil inlet 48a is suitable for connection to an oil reservoir not shown.

[0077] 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.

[0078] 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 bearing downstream 46, while the line 50 connected to the first outlet 48b of the distributor 48 supplies oil to the upstream bearing 44 for lubrication.

[0079] 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.

[0080] Figures 2 to 4 further show 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] The present invention offers a simple, effective and economical solution to this problem.

[0085] 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.

[0086] As illustrated in figures 5 and 6, the invention thus proposes an annular sealing skirt 80 which extends around the flanges 32a, 34a and which includes 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.

[0087] 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®.

[0088] 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.

[0089] 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.6]).

[0090] 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.

[0091] In the example shown, the first end 80a of the skirt 80 is fixed to an annular rib 84 of the first bearing support 32. This rib 84 extends radially outwards, here at an axial distance from the flange 32a.

[0092] The first end 80a of the skirt 80 can be oriented radially outwards so that a free peripheral edge 80al of this end 80a is oriented radially outwards.

[0093] The first end 80a of the skirt 80 is clamped against an annular face 84a, here downstream, of the rib 84 by means of an annular plywood 86. This plywood 86 can be sectored to facilitate its assembly.

[0094] The plywood 86 is fixed to the rib 84 by screws 87 which pass through holes in the rib 84, the end 80a of the skirt 80 and the plywood 86.

[0095] The plywood 86 may include a cylindrical rim 86a which surrounds the edge 80a of the end 80a or even a free peripheral edge 84al of the rib 84.

[0096] In the example shown, the second end 80b of the skirt 80 is fixed to the flange 34a of the second bearing support 34.

[0097] The second end 80b of the skirt 80 can be radially clamped onto the flange 34a by means of a fastening device 88 according to the invention.

[0098] 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. 6] 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.

[0099] Figures 7 to 15c illustrate a first embodiment of a fastening device 88 for the skirt 80.

[0100] Essentially, the fastening device 88 comprises

[0101] - at least one 90 plywood extending circumferentially around axis A and applied radially against the second axial end 80b of the skirt 80,

[0102] - an annular plate 92 fixed to the annular housing 36 and extending radially towards the outside relative to axis A at the level of the 90 plywood, and

[0103] - clamping elements 94 carried by the annular plate 92 and capable of applying a clamping force in the radial direction on the 90 plywood.

[0104] Since the plywood 90 must be capable of applying or transferring a radial force to the skirt 80, it must retain the ability to move freely in the radial direction and therefore cannot be annular and continuous over 360°. It thus has a circumferential orientation. The number of plywood 90s is not limited and can be 1, 2, 3, or 4, for example. When using two or more plywood 90s, they are arranged end-to-end around the axis A.

[0105] In the example shown, the plywood 90 is not perfectly cylindrical. For example, it has a general flattened S-shape, as in Figures 7 and 10. In this case, it may comprise two cylindrical sectors 90a and 90b of different diameters connected by a frustoconical sector 90c. The cylindrical sector 90b with the smaller diameter (with respect to axis A) is located downstream of the cylindrical sector 90a with the larger diameter (with respect to axis A). In the variant shown in Figures 8 and 9, the plywood 90 comprises only two sectors: a frustoconical sector 90c upstream and a cylindrical sector 90b downstream, with the cylindrical sector 90b defining the smaller diameter of the plywood, measured from axis A.

[0106] The drawings show that these particular shapes of the plywood 90 allow it to conform as closely as possible to the shape of the outer periphery of the flange 34a around which the plywood 90 is arranged. It can also be seen that the end 80b of the skirt 80 is radially interposed between the plywood 90 and the outer periphery of the flange 34a and adopts a similar shape due to the elastic deformation capacity of the skirt 80.

[0107] The plate 92 can be non-sectorized and therefore continuous over 360° around the main axis A. It is preferably flat and extends in a radial plane to the main axis A. Alternatively, the plate 92 could be sectorized and comprise two sectors of 180° each, to facilitate its assembly.

[0108] The plate 92 includes axially through holes 96 which are of three types: first holes 96a, second holes 96b and third holes 96c.

[0109] The first and second ports 96a, 96b allow for the mounting of at least one fluid connection 98 of said supply circuit 40 (Figures 8 and 9). The number of fluid connection(s) 98 is not limited.

[0110] Advantageously, it is this fluidic fitting 98 which allows the annular plate 92 to be fixed to the annular housing 36.

[0111] The fluidic fitting 98 comprises a tubular sleeve 100 oriented parallel to the axis A, and at least one external tab 102 integral with the sleeve 100 and extending in a radial plane to the axis A.

[0112] The fluidic fitting 98 can be formed from a single piece.

[0113] The sleeve 100 has a first end 100a engaged in a recess 103 of the annular housing 36 through the first orifice 96a or one of the first orifices 96a of the plate 92 ([Fig. 8]). The drawing shows that this first end 100a may be male and may carry an annular sealing gasket 101 which cooperates with the female recess 103 of the housing 36.

[0114] The annular plate 92 is axially intercalated between the or each leg 92 and the annular housing 36.

[0115] The sleeve 100 has a second end 100b, opposite the first end 100a, which is in fluidic communication with a conduit 104. It can be seen in the drawing that the conduit 104 can be of the male type and can carry an annular sealing gasket 101' which cooperates with the second end 100b of the female type of the sleeve 100.

[0116] The or each leg 102 has at least one orifice 106 for the passage of a screw 108 screwed into a hole 110 of the annular housing 36 through the second orifice 96b or one of the second orifices 96b of the plate 92 ([Fig.9]).

[0117] The third holes 96c of the plate 92 are used for mounting the clamping elements 94.

[0118] The clamping elements 94 are preferably regularly distributed around the axis A([Fig,10]).

[0119] The number of clamping elements 94 can be equal to the number of fusible screws 42 in the module.

[0120] Each of the clamping elements 94 is movable around a clamping axis B parallel to the axis A, independently of each other, between a first non-clamping position in which it does not apply any clamping force on the plywood 90, and a clamping position in which it applies a clamping force on the plywood 90.

[0121] We see in [Fig. 10] in particular that the clamping elements 94 are housed at least in part in at least one recess 112 of the annular housing 36.

[0122] As can be seen more clearly in [Fig.1 1], each of the clamping elements 94 comprises an eccentric 114 and a screw 116 for retaining the eccentric 114 on the annular plate 92, the eccentric 114 being movable around the screw 116 which is centered on the clamping axis B.

[0123] The screw 116 passes through one of the aforementioned third holes 96c of the annular plate and is screwed into a nut 118 which can be crimped into the hole 96c, which can be captive mounted, or simply attached.

[0124] A plain bearing 120 is advantageously mounted between the screw 116 and the eccentric 114. This plain bearing 120 can be formed by a cylindrical ring 122, one end of which includes an external annular flange 124. The ring 120 is suitable for being axially clamped by screw 116 against annular plate 92 and annular rim 124 is able to be separated by an axial play J1 from the eccentric 114 in order to allow it freedom of movement in particular in rotation around the clamping axis B.

[0125] The eccentric 114 includes a recessed or projecting recess 126 adapted to cooperate with a tool for rotating the eccentric 114 around its clamping axis B. This recess 126 can be of the hexagonal or six-sided type, as in the example shown.

[0126] This recess 126 is for example projecting and is preferably hollow to receive internally the screw 116 and the ring 120, as illustrated in the drawings.

[0127] The eccentric 114 has an external periphery comprising at least one cam surface 128.

[0128] In the embodiment of figures 7 to 15c, the cam surface 128 has at least one sharp edge 130 forming a hard point when the eccentric 114 is rotated around its clamping axis B. The or each sharp edge is straight and extends parallel to the clamping axis B.

[0129] The cam surface 128 may include chamfered edges 132 between two adjacent sharp edges 130. In the example illustrated in Figures 7 to 15c, the cam surface 128 includes a cylindrical surface 134 extending over approximately 180° and comprising, over the remaining 180°, three consecutive chamfered edges 132 connected to each other and to the cylindrical surface 134 by sharp edges 130.

[0130] The radial distance RI between the clamping axis B and the cylindrical surface 134 varies along this surface 134 and is maximum at the circumferential ends of the surface 134 (Figure 15a). The radial distance R2 between the intermediate chamfered face 132 and the clamping axis B is greater than the radial distances R3 between the other two chamfered faces 132 and the clamping axis B (Figure 15a).

[0131] In the embodiment shown in [Fig. 16], the cam surface 128 does not have a sharp edge and has a generally elliptical or teardrop shape. The radial distance between the clamping axis B and the surface 128 varies around the axis B and also has a maximum.

[0132] We will now describe the assembly of the fastening device 88 according to the invention with reference to figures 12 to 15c.

[0133] The annular plate 92 is first fixed to the housing 36 by the fluid fitting(s) 98. The clamping elements 94 are mounted on the annular plate 92 as shown in the drawings, by inserting each screw 116 into the ring 120 and then inserting the assembly into the recess of the eccentric 114. The screw 116 is screwed into the nut 118 so as to axially clamp the ring 120 against the annular plate 92. Alternatively, the clamping elements 94 could be mounted on the plate 92 before the plate 92 is fixed to the housing 36 by the fluid fitting(s) 98.

[0134] The eccentrics 114 are then in the unclamping position of Figure 15a in which they do not apply any clamping force on the plywood 90. It can be seen in this figure that the cylindrical surface 134 is opposite the plywood 90 and is separated by a radial clearance J2 from the plywood 90. In other words, the radial distance between the clamping axis B and the plywood 90 is greater than the aforementioned distance RI.

[0135] Each of the eccentrics 114 is then rotated about its clamping axis B to a second clamping position illustrated in Figure 15c, in which it applies a clamping force to the plywood 90 to radially clamp the skirt 80 against the flange 34a. This figure shows that the intermediate chamfered edge 132 is radially pressed against the plywood 90. In other words, the aforementioned radial distance between the clamping axis B and the plywood 90 is less than the aforementioned distance R2.

[0136] To move from the unclamped position in Figure 15a to the clamped position in Figure 15c, the eccentric 114 passed through intermediate positions such as those illustrated in Figures 14 and 15b, for example. In Figure 15b, for example, one of the chamfered edges 132 can be seen opposite and at a distance from the plywood 90, the aforementioned radial distance between the clamping axis B and the plywood 90 being greater than the aforementioned distance R3.

Claims

1. Demands Module (30) for an aircraft turbomachine (10), this module (30) comprising: - a first annular bearing support (32) which extends around a main axis (A) and which includes a first annular fixing flange (32a), - a second annular bearing support (34) which extends around the main axis (A) and which includes 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), - an annular housing (36) which extends around the main 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 housing (44) carried by the first bearing support (32) and a second bearing housing (46) carried by the second bearing support (34), - an oil supply circuit (40) for the chamber (38), and - an annular sealing skirt (80) which extends around 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 suitable for sealing around the flanges (32a, 34a), between the first and second bearing supports (32, 34), in particular in case of breakage of the fusible screws (42),said second axial end (80b) of the skirt (80) being fixed to the second bearing support (34) by a fixing device (88) comprising:, - at least one plywood (90) extending circumferentially around the main axis (A) and applied radially against the second axial end (80b) of the skirt (80), - an annular plate (92) fixed to the annular housing (36) and extending radially outwards with respect to the main axis (A) at the level of said at least one plywood (90), and - clamping elements (94) carried by the annular plate (92) and capable of applying a clamping force in a radial direction on the plywood (90), each of these clamping elements (94) being movable around a clamping axis (B) parallel to said main axis (A), independently of each other, between a first non-clamping position in which it does not apply a clamping force on the plywood (90), and a clamping position in which it applies said clamping force.

2. Module (30) according to claim 1, wherein the clamping elements (94) are regularly distributed around said main axis (A).

3. Module (30) according to claim 1 or 2, wherein the annular plate (92) is fixed to the annular housing (36) via at least one fluidic fitting (98) of said circuit (40).

4. Module (30) according to claim 3, wherein the fluidic fitting (98) comprises a tubular sleeve (100) oriented parallel to the main axis (A), and at least one external tab (102) integral with the sleeve (100) and extending in a radial plane to the main axis (A), the sleeve (100) having a first end (100a) engaged in a housing (103) of the annular housing (36) and a second end (100b), opposite the first end (100a), which is in fluidic communication with a conduit (104), said at least one tab (102) having at least one orifice (106) for the passage of a screw (108) screwed into a hole (110) of the annular housing (36).

5. Module (30) according to claim 4, wherein the annular plate (92) is axially intercalated between said at least one lug (102) and the annular housing (36).

6. Module (30) according to any one of the preceding claims, wherein the clamping elements (94) are housed at least in part in at least one recess (112) of said annular housing (36).

7. Module (30) according to any one of the preceding claims, wherein each of the clamping elements (94) comprises an eccentric (114) and a screw (116) for retaining the eccentric (114) on the annular plate (92), the eccentric (114) being movable around the screw (116) which is centered on the clamping axis (B).

8. Module (30) according to claim 7, wherein a plain bearing (20) is mounted between the screw (116) and the eccentric (114).

9. Module (30) according to claim 8, wherein the plain bearing (120) is formed by a cylindrical ring (122) one end of which includes an external annular rim (124), the ring (122) being axially clamped by the screw (116) against the annular plate (92) and the annular rim (124) being separated by an axial clearance (J2) from the eccentric (114).

10. Module (30) according to any one of claims 7 to 9, wherein the eccentric (114) comprises a recessed or projecting indentation (126) adapted to cooperate with a tool for rotating the eccentric (114) around its clamping axis (B).

11. Module (30) according to claim 10, wherein the imprint (126) is of the hexagonal or six-sided type.

12. Module (30) according to claim 10 or 11, depending on claim 9, wherein the recess (126) is projecting and hollow to internally receive said screw (116) and said ring (120).

13. Module (30) according to any one of claims 7 to 12, wherein the eccentric (114) has an external periphery comprising at least one cam surface (128), this cam surface (128) being able to comprise at least one sharp edge (130) forming a hard point when rotating the eccentric (114) around its clamping axis (B).

14. Module (30) according to any one of the preceding claims, wherein the clamping device (88) comprises several plywood pieces (90) which are arranged one after the other around the main axis (A).

15. Module (30) according to any one of the preceding claims, wherein said at least one plywood (90) comprises two cylindrical sectors (90a, 90b) of different diameters and connected together by a frustoconical sector (90c).

16. Module (30) according to any one of the preceding claims, wherein the annular plate (92) is non-sectorized.

17. Module (30) according to any one of claims 1 to 15, wherein the annular plate (92) is sectorized and comprises two sectors of 180° each.

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

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