MODULE FOR AN AIRCRAFT TURBOMACHINE

Abstract

Module (30) for an aircraft turbomachine (10), this module (30) comprising: - a bearing lubrication chamber (38) (44, 46), and - an oil supply circuit (40) for the chamber (38), this circuit (40) comprising an oil distributor (48) and at least one oil line (50), the oil distributor (48) being integral with a housing (36) and comprising at least one oil inlet (48a) and at least one first oil outlet (48b), the distributor (48) comprising a movable element (60) from a first position in which it permits fluid communication between the inlet (48a) and the outlet (48b), and a second position in which it prevents fluid communication between the inlet (48a) and the outlet (48b). Figure for the abbreviation: Figure 2

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 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 first 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 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, this circuit comprising a oil distributor and at least one oil line, the oil distributor being integral with the crankcase and comprising at least one oil inlet and at least one first oil outlet, the oil line being integral with the first bearing support and comprising one end connected to the first oil outlet of the distributor for the purpose of circulating oil from said inlet to the line via said outlet,

[0019] said end of the line being capable of being connected by male-female engagement in the axial direction with said outlet of the distributor and of being in fluidic communication with this outlet when the first and second flanges are applied axially against each other, and of being disconnected from said outlet and no longer being in fluidic communication with this outlet when the shear screws have broken and the first and second flanges are axially separated from each other,

[0020] the distributor comprising a body having an internal cavity which is connected to said inlet and said first outlet, the distributor further comprising a member housed in said cavity and movable from a first position in which it permits fluidic communication between the inlet and the outlet, and a second position in which it prohibits fluidic communication between the inlet and the outlet,

[0021] the distributor being further configured so that the element adopts its first position in normal operation when the end of the line is connected to the outlet of the distributor and a pressure difference between an oil flow at the first outlet and an oil flow at the inlet is less than or equal to a predetermined threshold, and that the element adopts its second position when the fusible screws have broken, the end of the line is disconnected from the outlet of the distributor and the pressure difference between the oil flow at the first outlet and the oil flow at the inlet is greater than the predetermined threshold.

[0022] 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. The axial displacement of the first bearing support, away from the second bearing support, causes the line to disconnect from the oil distributor. This results in a drop in pressure at the distributor outlet, causing the distributor's moving part to shift from its first position to its second position. The oil supply to the line and the housing is then cut off, thus limiting the risk of oil accumulation at the bottom of the housing and contamination of the engine's first oil passage.

[0023] The module according to the invention may comprise one or more of the following features, taken individually or in combination with each other: • the organ is forced into its first position by a returning element such as a spring;

[0024] — the organ is induced in its second position by a return element such as a spring ; • the component is mounted to move freely between two springs; • the organ has a general shape of alternator; • the distributor includes a second oil outlet which is connected to another line or to an oil nozzle; • when the organ is in its first position, it allows fluidic communication between the inlet and each of the first and second outlets, and when the organ is in its second position, it prohibits fluidic communication between the inlet and each of the first and second outlets; • the organ includes an external annular groove which is in fluidic communication with said inlet of the distributor; • when the organ is in its first position, the throat is in fluidic communication with each of the outlets, and when the organ is in its second position, the throat is no longer in fluidic communication with each of the outlets; • the throat is connected by a conduit to one of the axial ends of the organ; this conduit allows pressure equalization; • said pipe passes through an axial passage of the second bearing support; • the flange of the second bearing support is axially interposed between the flange of the first bearing support and another flange of the casing; • the flange of the second bearing support is fixed to the flange of the casing by non-shear screws;

[0025] — the distributor is of the hydraulic type;

[0026] — the first outlet of the distributor is oriented in the axial direction, in particular towards the first bearing support, and preferably upstream.

[0027] The present invention also relates to an aircraft turbomachine, comprising at least one module as described above. Brief description of the figures

[0028] 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:

[0029] [Fig-1] [Fig.1] is a schematic half-view in axial section of a part of a aircraft turbomachine,

[0030] [Fig.2] [Fig.2] is a partial schematic axial cross-sectional view of a bearing lubrication chamber,

[0031] [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,

[0032] [Fig.4] [Fig.4] is a view similar to that of [Fig.3] and shows the decoupling device with fusible screws here broken,

[0033] [Fig.5] [Fig.5] is a very schematic axial cross-sectional view of an oil distributor comprising a movable element located in a first position, and illustrates one embodiment of the invention,

[0034] [Fig. 6] [Fig. 6] is a view similar to that of [Fig. 5] and shows the oil distributor with the moving part located in a second position, and

[0035] [Fig.7] [Fig.7] is a graph showing the evolution of the oil pressure in the distributor as a function of the position of the component. Detailed description of the invention

[0036] Fig. 1 shows a turbomachine 10 for an aircraft, this turbomachine 10 being here a twin-spool turbojet.

[0037] Axis A designates the longitudinal axis of the turbomachine.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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].

[0046] 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 for being fixed together by screws 42 which are shear-off and more clearly visible in figures 2 to 4.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] In the example shown, the upstream bearing 44 is a roller bearing and the downstream bearing 46 is a ball bearing.

[0051] 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.

[0052] 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.

[0053] The oil inlet 48a is suitable for being connected to an oil reservoir not shown.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] The present invention offers a simple, effective and economical solution to this problem.

[0062] The invention first proposes a particular distributor 48, one embodiment of which is illustrated in figures 5 to 7.

[0063] The oil distributor 48 has its first outlet 48b which is suitable to be connected to the end 50a of the line 50 by male-female engagement in the axial direction.

[0064] When the end 50a of the pipe 50 is engaged in the outlet 48b of the distributor 48, or vice versa, the outlet 48b and the inlet 48a of the distributor 50 are in fluidic communication with each other ([Fig. 5]). This configuration corresponds to the default configuration and normal operating condition in which the flanges 32a, 34a of the bearing supports 32, 34a are axially pressed against each other and secured together by the shear screws 42.

[0065] When the end 50a of the pipe 50 is disengaged from the outlet 48b of the distributor 48, each outlet 48b, 48c and the inlet 48a of the distributor 48 are no longer in fluidic communication ([Fig. 6]). This scenario corresponds to the scenario in which the shear screws 42 have broken and the flanges 32a, 34a of the bearing supports 32, 34 are axially separated from each other.

[0066] Fluidic communication between the inlet 48a and the outlets 48b, 48c of the distributor 48 is allowed or prohibited by means of a movable element 60 in the distributor 48 so as to constitute a distributor spool.

[0067] The distributor 48 comprises a body 62 having an internal cavity 64 which is connected to the inlet 48a and to the outlets 48b, 48c. The member 60 is housed in the cavity 64 and is movable in this cavity 64 from a first position in which it allows fluidic communication between the inlet 48a and the outlets 48b, 48c ([Fig.5]), and a second position in which it prohibits fluidic communication between the inlet 48a and the outlets 48b, 48c ([Fig.6]).

[0068] The distributor 48 is further configured such that the member 60 assumes its first position in normal operation when the end 50a of the line 50 is connected to the outlet 48b of the distributor 48 and the pressure difference between the oil flow at the first outlet 48b and the oil flow at the inlet 48a is less than or equal to a predetermined threshold ([Fig. 5]), and that the member 60 assumes its second position when the shear screws 42 have broken, the end 50a of the line 50 is disconnected from the outlet 48b of the distributor 48, and the pressure difference between the oil flow at the first outlet 48b and the oil flow at the inlet 48a is greater than the predetermined threshold ([Fig.6]).

[0069] In other words, as illustrated in [Fig. 7], the operation of the distributor 48 is hydraulic. In normal operation (the line 50 is engaged in the outlet 48b - [Fig. 5]), the pressure at the outlet 48b of the distributor 48 is approximately equal to the pressure at the inlet 48a, within the limits of pressure losses. This means that the pressure difference AP between the oil flow rates at the outlet 48b and the inlet 48a is small (see the first parts C1, C2 of the curves in [Fig. 7]). In the event of breakage of the fusible screws 42 (the pipe 50 disengages from the outlet 48b - [Fig.6]), the pressure at outlet 48b of the distributor 48 drops abruptly (see second part Cl' of the curve representing the pressure at outlet 48b of the distributor 48), which in turn results in a drop in the pressure at inlet 48a of the distributor 48 (see second part C2' of the curve representing the pressure at inlet 48a of the distributor 48).The pressure difference AP' between the oil flow rates at outlet 48b and inlet 48a is therefore relatively large compared to the normal operating case (AP), and this pressure difference AP' will cause the component 60 to move from its first to its second position.

[0070] Figures 5 and 6 show that the member 60 is forced into its second position by a return element 70, such as a spring. In practice, the member 60 can be mounted flexibly between two springs 70, 72, although the spring 70 is not essential. When the pressure difference AP' is significant, the outlet pressure 48b is insufficient to compress the return element 70, which forces the member 60 into its second position.

[0071] The component 60 may have a general dumbbell shape as illustrated in the drawings, and include an internal annular groove 74 substantially in its middle. The inlet 48a of the distributor 48 preferably opens into this groove 74, regardless of the position of the component 60.

[0072] The second outlet 48c can open into the groove 74 when the organ 60 is in its first position ([Fig.5]), and can not open into the groove 74 when the organ 60 is in its second position ([Fig.6]).

[0073] The first output 48b can be connected directly to the second output 48c without going through the internal cavity 64 of the distributor 48.

[0074] It is therefore understood that the invention makes it possible to stop the oil supply to the enclosure 38 when a break in the fusible screws 42 occurs.

[0075] The rest position corresponds to the first position, the position which allows oil to be supplied to outlets 48c and 48b.

[0076] The annular groove 74 is preferably hydraulically connected to the cavity 64 by a conduit 76. This conduit 76 makes it possible to balance the pressure forces between the groove 74 and the end of the member 60 at the level of which the conduit 76 opens.

[0077] During initial operation or start-up of the turbomachine 10, the distributor 48 is supplied with oil at a gradually increasing flow rate, thus not generating a force exceeding the actuation threshold. This allows the component 60 to move from its second rest position to its first position. The return element 70 is then compressed.

[0078] It is therefore understood that a sudden drop in pressure at outlet 48b of distributor 48 causes a displacement of the member 60 towards its second position, whereas a start-up of the supply of distributor 48 and a progressive increase in pressure at inlet 48a of distributor 48 will not cause a displacement of the member 60 which remains in its first equilibrium position via the two springs 70, 72.

Claims

1. Demands Module (30) for an aircraft turbomachine (10), this module (30) comprising: - a first annular bearing support (32) which extends around an axis (A) and which includes a first annular fixing flange (32a), - a second annular bearing support (34) which extends around the 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 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 roller bearing (44) supported by the first bearing support (32) and a second roller bearing (46) supported by the second bearing support (34), and - an oil supply circuit (40) for the chamber (38), this circuit (40) comprising an oil distributor (48) and at least one oil line (50), the oil distributor (48) being integral with the housing (36) and comprising at least one oil inlet (48a) and at least one first oil outlet (48b), the oil line (50) being integral with the first bearing support (32) and comprising one end (50a) connected to the first oil outlet (48b) of the distributor (48) for the circulation of oil from said inlet (48a) up to the conduit (50) via said exit (48b), said end (50a) of the conduit (50) being able to be connected by male-female engagement in the axial direction with said outlet (48b) of the distributor (48) and to be in fluidic communication with this outlet (48b) when the first and second flanges (32a, 34a) are applied axially against each other, and to be disconnected from said outlet (48b) and no longer to be in fluidic communication with this outlet (48b) when the shear screws (42) have broken and the first and second flanges (32a, 32b) are axially separated from each other, The distributor (48) comprising a body (62) having an internal cavity (64) connected to said inlet (48a) and said first outlet (48b), the distributor (48) further comprising a member (60) housed in said cavity (64) and movable from a first position in which it permits fluid communication between the inlet (48a) and the outlet (48b), and a second position in which it prohibits fluid communication between the inlet (48a) and the outlet (48b), the distributor (48) further being configured such that the member (60) assumes its first position in normal operation when the end (50a) of the line (50) is connected to the outlet (48a) of the distributor (48) and a pressure difference between an oil flow rate at the first outlet (48b) and an oil flow rate at the inlet (48a) is less than or equal to a predetermined threshold, and that the member (60) assumes its second position when the fusible screws (42) have broken,that the end (50a) of the line (50) is disconnected from the outlet (48b) of the distributor (48) and that the pressure difference between the oil flow at the first outlet (48b) and the oil flow at the inlet (48a) is greater than the predetermined threshold.

2. Module (30) according to claim 1, wherein the member (60) is forced into its first position by a return element (72) such as a spring.

3. Module (30) according to claim 1 or 2, wherein the member (60) is mounted movable between two springs (70, 72).

4. Module (30) according to any one of the preceding claims, wherein the component (60) has a general shape of alternator.

5. Module (30) according to any one of the preceding claims, wherein the distributor (48) includes a second oil outlet (48b) which is connected to another line (50) or to an oil nozzle (52).

6. Module (30) according to the preceding claim, wherein, when the member (60) is in its first position, it permits fluidic communication between the inlet (48a) and each of the first and second outlets (48b, 48c), and when the member (60) is in its second position, it prohibits fluidic communication between the inlet (48a) and each of the first and second outlets (48b, 48c).

7. Module (30) according to any one of the preceding claims, wherein the component (60) comprises an external annular groove (74) which is in fluid communication with said inlet (48a) of the distributor (48).

8. Module (30) according to the preceding claim in dependence on claim 6, wherein, when the member (60) is in its first position, the groove (74) is in fluidic communication with each of the outlets (48b, 48c), and when the member is in its second position, the groove (74) is no longer in fluidic communication with each of the outlets (48b, 48c).

9. Module (30) according to claim 7 or 8, wherein the groove (74) is connected by a conduit (76) to one of the axial ends of the member (60).

10. Module (30) according to any one of the preceding claims, wherein said conduit (50) passes through an axial passage (54) of the second bearing support (34).

11. 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).

12. 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.

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

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