System for cooling and lubricating an aircraft turbine engine bearing and method for using same

Abstract

The invention relates to a system (1) for cooling and lubricating a bearing of an aircraft turbine engine (30), comprising: - a bearing chamber (2) defining an internal space (V) and comprising an air intake passage (8); - a supply circuit (9) for supplying the internal space (V) with cooling and lubricating fluid; - a vent circuit (14) configured to discharge the air loaded with cooling and lubricating fluid out of the internal space (V) to a separator (16); - a control line (10) fed by the supply circuit (9) and opening into the vent circuit (14), wherein the control line (10) comprises a valve that can be actuated so as to take an open position and a closed position in order to respectively allow and prevent the entry of the cooling and lubricating fluid into the vent circuit (14).

Description

Cooling and lubrication system for an aircraft turbomachine bearing and method of using same

[0001] The present invention relates to the field of aircraft turbomachines and more specifically relates to a system for cooling and lubricating one or more bearings and its method of use.

[0002] As is known, an aircraft turbomachine extends along a longitudinal axis and allows the aircraft to be moved from a flow of air circulating from front to rear in the turbomachine during a thrust phase. The aircraft turbomachine comprises from front to rear one or more compressors, a combustion chamber and one or more turbines. Each turbine is rotationally fixed to a compressor via a shaft extending along the longitudinal axis. The aircraft turbomachine typically comprises a low-pressure shaft, connecting a low-pressure compressor and a low-pressure turbine, and a high-pressure shaft, surrounding the low-pressure shaft and connecting a high-pressure turbine and a high-pressure compressor.

[0003] In practice, the low-pressure shaft and the high-pressure shaft are supported at the front and rear by bearings, for example of the ball or roller bearing type, which must be lubricated and cooled. It is known for this to house the bearings in enclosures inside which they are bathed in an oil mist. Each enclosure typically comprises a stator wall extending around the rotating shaft and the bearing as well as seals between the stator wall and the rotating shaft, for example one at the front and one at the rear. The oil is supplied by a supply circuit and discharged by gravity. Passages, typically formed in the labyrinth-type seals, allow the admission of pressurized air, in particular taken from the compressor, in order to confine the oil in the bearing enclosure.The air loaded with suspended oil droplets is evacuated into a degassing tube and guided to a centrifugal separator to recover the oil.

[0004] In practice, suspended oil droplets discharged into the vent tube cause pressure losses in the vent tube, which increase the pressure in the bearing enclosure. This reduces the pressure difference across the seals and has the effect of undesirably reducing the seal. It is therefore desirable to reduce the amount of oil discharged through the vent tube. This also reduces oil consumption and thus reduces the interval between refills.

[0005] Furthermore, in the presence of high temperatures above 250°C, the oil present in the degassing tube is likely to form a coke deposit on the walls, which reduces the internal section and increases the pressure losses undesirably. Such a coking phenomenon is particularly likely to be observed for bearings mounted at the rear of the aircraft turbomachine whose degassing tube is mounted in a turbine casing arm crossing the air stream to reach the centrifugal separator in the accessory relay box located in the nacelle surrounding the aircraft turbomachine.

[0006] It is known from patent application FR3111164A1 to use a rotating blade to scrape the coke deposit behind the centrifugal separator. This does not, however, prevent the formation of coke in the degassing tube. Also known from application FR3133887A1 is a system for degassing a bearing enclosure comprising a main discharge duct for a first fraction of an air-lubricant mixture and a duct for recovering the lubricant and a second fraction of the air-lubricant mixture joining at least partly the main discharge duct.

[0007] The invention thus aims to limit pressure losses in the degassing tube to promote sealing in the bearing enclosure of an aircraft turbomachine. PRESENTATION OF THE INVENTION

[0008] The invention relates to a system for cooling and lubricating at least one aircraft turbomachine bearing comprising: a bearing enclosure delimiting an internal volume in which the bearing extends, the bearing enclosure comprising at least one air intake passage in the internal volume, a supply circuit configured to supply the internal volume with a cooling and lubricating fluid, and a degassing circuit configured to evacuate the air loaded with cooling and lubricating fluid from the internal volume, the degassing circuit comprising a separator configured to extract the cooling and lubricating fluid in the air loaded with cooling and lubricating fluid.

[0009] The invention is remarkable in that the cooling and lubrication system comprises a control line supplied by the supply circuit and opening towards the degassing circuit, the control line comprising a controllable valve: in an open position, to authorize the admission of the cooling and lubrication fluid into the degassing circuit, and in a closed position, to prohibit the admission of the cooling and lubrication fluid into the degassing circuit.

[0010] The control line advantageously allows the quantity of cooling and lubricating fluid, typically oil, which is discharged into the degassing circuit to be regulated in a simple and practical manner, in particular according to the speed of the aircraft turbomachine. The open position of the valve is particularly suitable for high speeds of the aircraft turbomachine, because the oil taken from the supply circuit allows the oil-laden air circulating in the degassing circuit to be cooled and thus effectively reduces the risk of coking when the oil is exposed to high temperatures. This prevents the formation of a coke deposit on the walls of the degassing circuit, which makes it possible to maintain a large flow section with minimal pressure losses. The sealing of the internal volume ensured by the pressurized air is thus optimal.

[0011] The closed position of the valve is suitable for low speeds of the aircraft turbomachine, for which a low oil flow rate in the degassing circuit makes it possible to limit pressure losses and therefore ensure good sealing in the bearing enclosure. Thanks to the pilot line which provides additional oil during high speeds of the aircraft turbomachine, the pressurization circuit supplying the internal volume with air can advantageously be undersized compared to the prior art.

[0012] According to one aspect of the invention, the cooling and lubrication system comprises a passive type control member for the open position and the closed position of the valve. This makes it possible to regulate the quantity of oil in the degassing circuit in a simple, practical and inexpensive manner.

[0013] According to one aspect of the invention, the control member is configured to control the open position of the valve when the pressure of the cooling and lubricating fluid in the supply circuit or in the pilot line upstream of the valve is greater than a predetermined threshold. This corresponds to high speeds. This makes it possible to control the opening of the valve as a function of the speed of the aircraft turbomachine in a passive manner.

[0014] According to one aspect of the invention, the pilot line extends into the bearing enclosure to reduce the space requirement and the quantity of piping.

[0015] According to one aspect of the invention, the control line opens into the internal volume, opposite an inlet of the degassing circuit. Such a control line is advantageously simple to integrate into the bearing enclosure. The outlet of the control line is typically equipped with a nozzle which can be mounted projecting opposite the inlet of the degassing circuit to direct the cooling and lubricating fluid there.

[0016] According to another aspect of the invention, the pilot line extends outside the bearing enclosure so as not to increase the size of the bearing enclosure.

[0017] According to one aspect of the invention, the control line connects the supply circuit and the degassing circuit in parallel with the internal volume. The output of the control line, typically a nozzle, opens directly into the degassing circuit, downstream of the inlet.

[0018] According to a preferred aspect of the invention, the cooling and lubricating fluid circulates from upstream to downstream in the supply circuit, the pilot line opening into the supply circuit upstream of at least one heat exchanger of the supply circuit with a fuel circuit of the aircraft turbomachine. The oil taken by the pilot line to reach the degassing circuit is thus sufficiently cold to avoid the occurrence of coking. In addition, the reduction in the temperature of the air-oil mixture in the degassing circuit is beneficial for the efficiency of the separator, reducing oil consumption despite the increase in the flow rate of oil that the separator has to treat.

[0019] According to one aspect of the invention, the control line opens into the degassing circuit at a distance from the inlet of the degassing circuit of less than 50 mm, and preferably greater than 5 mm. This makes it possible to limit pressure losses from the inlet of the degassing circuit.

[0020] According to one aspect of the invention, the control line comprises a nozzle configured to vaporize the cooling and lubricating fluid supplying the degassing circuit. This makes it possible to inject the oil in the form of droplets into the degassing circuit.

[0021] The invention also relates to an aircraft turbomachine comprising: an air stream extending along a longitudinal axis oriented from front to rear in the direction of circulation of an air flow during a thrust phase of the aircraft turbomachine, at least one turbine, and at least one cooling and lubrication system as described previously extending behind the turbine.

[0022] In such a cooling and lubrication system, the degassing circuit is more likely to be exposed to high temperatures. The invention advantageously makes it possible to effectively reduce the risk of coking.

[0023] The invention also relates to an aircraft turbomachine comprising: an air stream extending along a longitudinal axis oriented from front to rear in the direction of circulation of an air flow during a thrust phase of the aircraft turbomachine, at least one turbine and at least one arm extending radially in the air stream behind the turbine, at least one cooling and lubrication system as described previously, the degassing circuit passing through the arm.

[0024] In such a cooling and lubrication system, the degassing circuit is more likely to be exposed to high temperatures. The invention advantageously makes it possible to effectively reduce the risk of coking.

[0025] The invention also relates to a method of using a cooling and lubrication system as described above, in which the valve is initially in the closed position to prohibit the admission of the cooling and lubricating fluid into the degassing circuit, the method of use comprising controlling the open position of the valve, to authorize the admission of the cooling and lubricating fluid into the degassing circuit.

[0026] According to one aspect of the invention, the method of use also consists, when the valve is in the open position of the valve to allow the admission of the cooling and lubricating fluid into the degassing circuit, in controlling the closed position to prohibit the admission of the cooling and lubricating fluid into the degassing circuit. PRESENTATION OF FIGURES

[0027] The invention will be better understood upon reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0028] This is a schematic representation in longitudinal section of an aircraft turbomachine comprising a bearing cooling and lubrication system according to one embodiment of the invention.

[0029] This is a schematic representation of the cooling and lubrication system of the.

[0030] This is a schematic representation of the pilot line of the cooling and lubrication system with the valve in an open position.

[0031] This is a schematic representation of the pilot line of the cooling and lubrication system with the valve in a closed position.

[0032] This is a schematic representation of the control line of the cooling and lubrication system with a control line according to another embodiment of the invention.

[0033] This is a schematic representation of the control line of the cooling and lubrication system with a control line according to another embodiment of the invention.

[0034] This is a schematic representation in longitudinal section of an aircraft turbomachine comprising a bearing cooling and lubrication system according to another embodiment of the invention.

[0035] It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention if necessary. DETAILED DESCRIPTION OF THE INVENTION

[0036] With reference to the, the invention relates to an aircraft turbomachine 30 comprising a cooling and lubrication system 1 for one or more bearings 3. The aircraft turbomachine 30 conventionally extends along a longitudinal axis X and makes it possible to move the aircraft from an air flow circulating from front to rear in the turbomachine 30 during a thrust phase. The aircraft turbomachine 30 typically comprises from front to rear one or more compressors 31, 32, a combustion chamber and one or more turbines 33, 34. Each turbine 33, 34 is rotationally secured to a compressor 31, 32 via a shaft 5, 6 extending along the longitudinal axis X. In this example, the aircraft turbomachine 30 comprises a low pressure shaft 5, connecting a low pressure compressor 31 and a low pressure turbine 34, and a high pressure shaft 6, surrounding the low pressure shaft 5 and connecting a high pressure turbine 33 and a high pressure compressor 32.The low pressure shaft 5 and the high pressure shaft 6 are supported at the front and rear by bearings 3, for example of the ball or roller bearing type. Only one bearing 3 at the rear of the aircraft turbomachine 30 is shown in the, but the invention applies to any bearing 3 supporting any shaft 5, 6 of the aircraft turbomachine 30. The invention also applies to several neighboring bearings 3.

[0037] According to the invention and with reference to Figures 1 and 2, the cooling and lubrication system 1 comprises: a bearing enclosure 2 delimiting an internal volume V in which the bearing 3 (or several neighboring bearings 3) extends and comprising one or more air intake passages 8 A in the internal volume V, a supply circuit 9 configured to supply the internal volume V with a cooling and lubricating fluid H, typically oil, a degassing circuit 14 configured to evacuate the oil-laden air AH from the internal volume V, and comprising a separator 16 configured to extract the oil H in the oil-laden air AH, a control line 10 supplied by the supply circuit 9 and opening towards the degassing circuit 14, the control line 10 comprising a valve 11 controllable, in an open position O, to authorize the admission of the oil H into the degassing circuit 14, and in a closed position F,to prevent the admission of oil H into the degassing circuit 14.,

[0038] The integration of a control line 10 equipped with a valve 11 between the supply circuit 9 and the degassing circuit 14 advantageously makes it possible to regulate the quantity of oil H discharged into the degassing circuit 14 in a simple and practical manner, in particular as a function of the speed of the aircraft turbomachine 30. The open position O of the valve 11 is particularly suitable for high speeds of the aircraft turbomachine 30, because the oil H taken from the supply circuit 9 makes it possible to cool the air loaded with oil AH circulating in the degassing circuit 14 and thus effectively reduces the risk of coking when the oil H is exposed to high temperatures, in particular above 250°C, preferably 300°C. This prevents the formation of a coke deposit on the walls of the degassing circuit 14, which makes it possible to maintain a large passage section with minimal pressure losses.The sealing of the internal volume V ensured by the pressurized air A is thus optimal.

[0039] The closed position F of the valve 11 is suitable for the low speeds of the aircraft turbomachine 30, for which a low flow rate of oil H in the degassing circuit 14 makes it possible to limit the pressure losses and therefore to ensure good sealing in the bearing enclosure 2. Thanks to the control line 10 which provides additional oil H during the high speeds of the aircraft turbomachine 30, the pressurization circuit supplying the internal volume with air can advantageously be undersized compared to the prior art.

[0040] Conventionally and as illustrated in the, the bearing enclosure 2 comprises a stator wall 4 extending around the shaft 5, 6 of the aircraft turbomachine 30 and the bearing 3, delimiting the internal volume V. The bearing 3 comprises a stator support element secured to the stator wall 4 and a rotor guide element driven in rotation by the shaft 5, 6. The bearing enclosure 2 also comprises seals 7, in particular of the dynamic type, typically of the labyrinth type, between the stator wall 4 and the shaft 5, 6, for example one at the front and one at the rear as illustrated in the. The air intake passages 8 A are typically formed in the labyrinth-type seals 7 and allow air A to be admitted under pressure, in particular taken from the compressor 31, 32, in order to confine the oil H in the bearing enclosure 2.

[0041] Still with reference to the, the oil H supply circuit 9 conventionally comprises, from upstream to downstream in the direction of circulation of the oil H, a reservoir 20, a supply pump 21, preferably a filter (not shown), one or more heat exchangers of the air / oil H type or oil H / fuel type, and an outlet 24 typically provided with a nozzle. The nozzle makes it possible to supply the internal volume V with oil H. In this example, a main exchanger 22 of the oil H / fuel type (“Fuel Cooled Oil Cooler FCOC”) and a secondary exchanger 23 of the oil H / fuel type are shown from upstream to downstream. These exchangers 22 and 23 are optional, and it is also possible to have an exchanger 22 without the presence of an exchanger 23. When present, the H oil / fuel type exchanger 23 is preferably dedicated to cooling the fuel by the oil under certain conditions.In this case it will be called OCFC for “Oil Cooled Fuel Cooler”, which implies that the oil is then heated by heat exchange with the hotter fuel.

[0042] Still with reference to the, the cooling and lubrication system 1 also conventionally comprises a discharge circuit 17 configured to discharge by gravity the oil H accumulated against the stator wall 4. The discharge circuit 17 conventionally comprises, from upstream to downstream in the direction of circulation of the oil H, a pump (not shown) and a separator 18 adapted to remove the air A contained in the oil H and known to those skilled in the art under the term “oil deaerator”. The separator 18 is for example arranged at the inlet of the reservoir 20 for the return of the oil H. The oil H returned to the reservoir 20 is then reinjected into the supply circuit 9 via the supply pump 21, while the air A is discharged outside the aircraft turbomachine 30.

[0043] Still with reference to the, the degassing circuit 14 makes it possible to evacuate the air loaded with oil AH from the internal volume V. The degassing circuit 14 comprises a separator 16 adapted to extract the oil droplets H contained in the air and known to those skilled in the art under the term “air de-oiler”. The separator 16 of the degassing circuit 14 is preferably of the centrifugal type and known to those skilled in the art under the term “rotor de-oiler”.

[0044] In the example of 1a, the separator 16 of the degassing circuit 14 is mounted in the nacelle 35 surrounding the aircraft turbomachine 30 and is rotated by an accessory gearbox 36 (“accessory gearbox AGB”). In this example, to convey the oil-laden air AH into the separator 16, the degassing circuit 14 extends in a turbine casing arm 37 extending radially in the air stream 38 behind the low-pressure turbine 34. Due to its location in the air stream 38, such a turbine casing arm 37 is likely to be exposed to high temperatures and the integration of a control line 10 according to the invention is particularly advantageous for avoiding coking.

[0045] Laillustrates another preferred embodiment of the invention which differs from la in that the separator 16 is mounted integral in rotation with the low pressure shaft 5, in this example behind the bearing 3. The degassing circuit 14 extends in this example behind the low pressure turbine 34, in particular in the low pressure shaft 5, such an arrangement being known to those skilled in the art under the term “center vent tube” and described for example in application FR2929325A1. The invention is also advantageous for such an arrangement capable of exposing the degassing circuit 14 to high temperatures.

[0046] With reference to the and as described previously, the control line 10 is supplied at the inlet by the supply circuit 9 and opens at the outlet towards the degassing circuit 14. The control line 10 makes it possible in practice to take a portion of the oil H, initially intended to supply the internal volume V, to inject it directly into the degassing circuit 14, preferably using a nozzle 13 positioned at the outlet of the control line 10.

[0047] In this example, the control line 10 connects the supply circuit 9 and the degassing circuit 14. Still in this example, the control line 10 is positioned outside the internal volume V. The control line 10 thus opens into the supply circuit 9 upstream of the outlet 24 in the internal volume V.

[0048] Preferably, as illustrated in Figures 2 and 3, the pilot line 10 opens into the supply circuit 9 downstream of the main exchanger 22, and preferably upstream of the secondary exchanger 23, that is to say at the coldest point of the oil H since the oil H then passing into the secondary exchanger 23 called OCFC can be heated by the fuel. In this way, the oil H taken makes it possible to effectively cool the air loaded with oil AH in the degassing circuit 14. The reduction in the temperature of the air-oil mixture in the degassing circuit 14 is beneficial for the efficiency of the separator 16, reducing the consumption of oil H despite the increase in the flow rate of oil that the separator 16 has to treat.

[0049] Still in the example of figures 2 and 3, the control line 10 preferably opens upstream of the inlet 15 of the degassing circuit 14, preferably at a distance d less than 50 mm and greater than 5 mm. This makes it possible to reduce the pressure losses over the entire degassing circuit 14.

[0050] With reference to Figures 2 to 4, the valve 11 is mounted on the pilot line 10 and allows the circulation of the oil H in the open position O shown in the, and prohibits the circulation of the oil H in the closed position F shown in the. The valve 11 preferably has only two positions, namely the open position O and the closed position F.

[0051] With reference to Figures 3 and 4, the valve 11 is preferably of the slide type and controlled by a control member 12, typically a return member such as a spring. Such a valve 11 is passively controlled from the pressure P of the oil H in the supply circuit 9 or the pilot line 10 upstream of the valve 11. When the pressure P of the oil H in the supply circuit 9 is greater than a predetermined threshold S, corresponding to a low speed of the aircraft turbomachine 30, the control member 12 moves the valve 11 into the open position O. When the pressure P of the oil H in the supply circuit 9 is lower than the predetermined threshold S, corresponding to a high speed of the aircraft turbomachine 30, the control member 12 moves the valve 11 into the closed position F.The pressure P of the oil H in the feed circuit 9 is advantageously linked to the speed of the aircraft turbomachine 30 because the feed pump 21 of the feed circuit 9 is typically driven in rotation by a shaft 5, 6 of the aircraft turbomachine 30. The threshold S is judiciously chosen according to the cooling requirements. Such a passive valve architecture 11 is furthermore simple, practical and inexpensive.

[0052] La represents another embodiment of the invention differing from la in that the control line 10 is positioned in the bearing enclosure 2 and connects the supply circuit 9 and the degassing circuit 14. The control line 10 opens at the inlet in this example upstream of the outlet 24 of the supply circuit 9 and downstream of the inlet 15 of the degassing circuit 14. As previously, the control line 10 makes it possible to take a portion of the oil H, initially intended to supply the internal volume V, to inject it directly into the degassing circuit 14. Such an assembly reduces the size as well as the quantity of piping.

[0053] La represents another embodiment of the invention differing from la in that the pilot line 10 opens into the internal volume V opposite the inlet 15 of the degassing circuit 14. Such a pilot line 10 is simple and practical to integrate into the bearing enclosure 2, the nozzle 13 being able in particular to be mounted projecting. Preferably, the distance d between the outlet of the pilot line 10 and the inlet 15 of the degassing circuit 14 is less than 50 mm and preferably greater than 5 mm. This makes it possible to effectively direct the oil H from the pilot line 10 into the degassing circuit 14.

[0054] The invention also relates to a method of using the cooling and lubrication system 1, in which the valve 11 is initially in the closed position F illustrated on the prohibiting the circulation of the oil H. The method of use comprises a step of controlling the open position O of the valve 11 illustrated on the authorizing the circulation of the oil H.

[0055] Preferably, the control member 12 is of the passive type and maintains the closed position F as long as the pressure P of the oil H is lower than the predetermined threshold S, corresponding to a low speed of the aircraft turbomachine 30. This makes it possible to limit the quantity of oil in the degassing circuit 14 and thus to reduce the pressure losses for better sealing of the bearing enclosure 2 at low speed.

[0056] When the pressure P of the oil H becomes higher than the predetermined threshold S, corresponding to a high speed of the aircraft turbomachine 30, the control member 12 moves the valve 11 into the open position O. This makes it possible to inject cold oil H into the degassing circuit 14 to avoid the occurrence of coking at high speed which would reduce the section of the degassing circuit 14 in the medium term.

[0057] Preferably, when the pressure P of the oil H becomes lower than the predetermined threshold S, the control member 12 moves the valve 11 back into the closed position F. The invention thus makes it possible to regulate the quantity of oil H in a simple and practical manner in the degassing circuit 14 to maintain low pressure losses at low speed and protect against coking at high speed of the aircraft turbomachine 30. The invention thus makes it possible to decorrelate the need for cooling the degassing circuit 14 at high speed and that for pressurizing the bearing enclosure 2 at low speed.

Claims

Cooling and lubrication system (1) for at least one bearing (3) of an aircraft turbomachine (30) comprising: a bearing enclosure (2) delimiting an internal volume (V) in which the bearing (3) extends, the bearing enclosure (2) comprising at least one air intake passage (8) (A) in the internal volume (V), a supply circuit (9) configured to supply the internal volume (V) with a cooling and lubricating fluid (H), a degassing circuit (14) configured to evacuate the air loaded with cooling and lubricating fluid (AH) from the internal volume (V), the degassing circuit (14) comprising a separator (16) configured to extract the cooling and lubricating fluid (H) in the air loaded with cooling and lubricating fluid (AH),the cooling and lubrication system (1) being characterized in that it comprises a control line (10) supplied by the supply circuit (9) and opening towards the degassing circuit (14), the control line (10) comprising a valve (11) controllable in an open position (O), to authorize the admission of the cooling and lubrication fluid (H) into the degassing circuit (14), and in a closed position (F), to prohibit the admission of the cooling and lubrication fluid (H) into the degassing circuit (14)., Cooling and lubrication system (1) according to claim 1, comprising a passive type control member (12) for the open position (O) and the closed position (F) of the valve (11). Cooling and lubrication system (1) according to claim 2, wherein the control member (12) is configured to control the open position (O) of the valve (11) when the pressure (P) of the cooling and lubrication fluid (H) in the supply circuit (9) or in the pilot line (10) upstream of the valve (11) is greater than a predetermined threshold (S). Cooling and lubrication system (1) according to one of claims 1 to 3, wherein the control line (10) extends into the bearing enclosure (2). Cooling and lubrication system (1) according to claim 4, in which the control line (10) opens into the internal volume (V), opposite an inlet (15) of the degassing circuit (14). Cooling and lubrication system (1) according to one of claims 1 to 3, wherein the control line (10) extends outside the bearing enclosure (2). Cooling and lubrication system (1) according to one of claims 1 to 4 and 6, in which the control line (10) connects the supply circuit (9) and the degassing circuit (14) in parallel with the internal volume (V). Cooling and lubrication system (1) according to one of claims 1 to 7, wherein the control line (10) comprises a nozzle (13) configured to vaporize the cooling and lubrication fluid (H) supplying the degassing circuit (14). Aircraft turbomachine (30) comprising: an air stream (38) extending along a longitudinal axis (X) oriented from front to rear in the direction of circulation of an air flow during a thrust phase of the aircraft turbomachine (30), at least one turbine (33, 34) and at least one arm (37) extending radially in the air stream (38) behind the turbine (33, 34), at least one cooling and lubrication system (1) according to one of claims 1 to 8, the degassing circuit (14) passing through the arm (37). Method of using a cooling and lubrication system (1) according to one of claims 1 to 8, in which the valve (11) is initially in the closed position (F) to prohibit the admission of the cooling and lubricating fluid (H) into the degassing circuit (14), the method of use consisting in controlling the open position (O) of the valve (11), to authorize the admission of the cooling and lubricating fluid (H) into the degassing circuit (14).

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