OIL TANK FOR A G-NEGATIVE COMPATIBLE TURBOMACH WITH CYCLONE SEPARATOR

Description

Domain

[0001] The invention relates to the field of turbomachinery reservoirs. More specifically, the invention relates to the field of oil reservoirs used to lubricate turbomachinery components, including an unfaired variable-pitch propeller and / or a variable-pitch stator. Previous art

[0002] Aircraft turbomachinery with at least one unducted propeller is known as an "open rotor" or "unducted fan." Within this category, there are those with two unducted, counter-rotating propellers (known as UDF for "Unducted Dual Fan") and those with a single unducted propeller and a stator with multiple blades (known as USF for Unducted Single Fan).

[0003] These turbomachines are distinguished by the use of a propeller outside the nacelle (unfaired) instead of an internal fan.

[0004] The propeller or propellers forming the propulsion unit generally include a blade pitch control system, also known as a variable pitch system. This system allows the propeller blades to adjust their angle according to the aircraft's flight phases (takeoff, cruise, landing, etc.) to ensure optimal thrust management in all turbomachine flight conditions.

[0005] In the case of turbomachinery with a single unshod propeller and a stator, the latter may also include a variable pitch system to improve the turbomachine's performance. An example of such a turbomachine is disclosed in published patent document FR 3 107 319 A1.

[0006] Variable pitch systems may require a continuous oil supply to enable blade pitch control and engine thrust management under all turbomachine flight conditions (nominal and extreme). State-of-the-art designs utilize a main lubrication circuit that supplies oil to the various engine components (bearings, gearbox, etc.) for lubrication and / or cooling. This circuit is supplied with oil from a main turbomachine reservoir, which includes an oil inlet at the top and an outlet at the bottom, ensuring continuous oil supply during flight attitudes under gravity or positive G-forces.

[0007] While such tanks are perfectly adequate when the aircraft is flying in positive G conditions, on the other hand, when it comes to flight phases under zero or negative load factor (zero G or negative G), i.e., in the event of aircraft maneuvering or in the event of an updraft, these tanks no longer fully supply the oil to the pitch actuation system.

[0008] Indeed, zero-G or negative-G flight phases are temporary flight phases (generally lasting less than 30 seconds for civil aircraft) in which the aircraft is subjected to negative accelerations, for example, when it undergoes sudden decreases in altitude.

[0009] To this end, the oil contained in the main tank is then reversed, the oil is no longer located near the outlet in the lower part, which generates a cut in the oil supply, causing air to pass into the variable timing circuit(s), thus generating harmful consequences on the operation of the turbomachine which may induce a loss of control of the aircraft.

[0010] It is possible to use tanks such as those found on fighter jets, where negative G-force flight phases are frequent and essential. However, these tanks are pressurized, which implies a significant increase in weight and cost, incompatible with turbomachinery that includes at least one unfaired propeller.

[0011] Furthermore, a known solution to avoid damaging the propeller pitch control circuit, in the event of negative G-forces, is to supply oil via a system other than the turbomachine's main oil reservoir. However, such a solution results in significant bulk and mass within the turbomachine and requires complex management of the oil supply to the variable pitch system.

[0012] The published patent document FR 3 010 133 A1 discloses a tank comprising an inclined partition equipped at its ends with through orifices for continuous feeding of the turbomachine.

[0013] Document FR 2 621 562 A1 relates to a turbomachine tank comprising a main enclosure and an auxiliary enclosure having a partition with orifices on a plate and a membrane capable of closing the orifices in the event of negative gravity flight.

[0014] However, the solutions proposed by prior art documents have room for improvement in order to allow, for example, a larger volume of oil available to supply the turbomachine components in the event of flight in negative G, and without hindering said volume during the return to positive G. Summary of the invention Technical problem

[0015] The present invention aims to overcome at least one of the drawbacks of the aforementioned prior art. More specifically, the invention aims to provide an oil tank designed to allow the aircraft to safely perform temporary phases of flight in negative gravity, without increasing the weight and cost of the tank. Technical solution

[0016] The invention relates to an oil reservoir for an aircraft turbomachine, comprising: a main enclosure suitable for containing the oil; an oil-air mixed inlet, disposed on the main enclosure; an oil outlet; an auxiliary enclosure, comprising a wrap-around wall, and two end walls adjacent to said wrap-around wall, at least one of the two end walls comprising at least one oil passage with the interior of the main enclosure, at least one auxiliary inlet opening tangentially to the wrap-around wall and passing through the auxiliary enclosure for connection to an auxiliary circuit; an auxiliary outlet, tangential to a larger diameter section of the wrap-around wall, said auxiliary outlet passing through the auxiliary enclosure for connection to the auxiliary circuit, the oil outlet being disposed on the auxiliary enclosure or on the main enclosure.

[0017] The oil flow from at least one auxiliary inlet to the auxiliary outlet allows the oil to flow along a spiral path, where it is subjected to centrifugal forces that stabilize the flow. This flow is stabilized particularly at the auxiliary outlet to ensure that it is constantly supplied with oil.

[0018] According to an advantageous embodiment of the invention, the enveloping wall is integrally formed with the main enclosure, and said enveloping wall preferably comprises a conical circular shape.

[0019] According to an advantageous embodiment of the invention, at least one auxiliary inlet opens tangentially into a smaller diameter section of the enveloping wall.

[0020] According to an advantageous embodiment of the invention, at least one oil passage is in a central position on the corresponding end wall.

[0021] According to an advantageous embodiment of the invention, at least one oil passage comprises a channel extending axially from the corresponding end wall into the interior of the auxiliary enclosure.

[0022] According to an advantageous embodiment of the invention, at least one channel extends over at least 30% or 20% of a total axial extent of the auxiliary enclosure.

[0023] According to an advantageous embodiment of the invention, at least one auxiliary inlet is near one of the two end walls.

[0024] According to an advantageous embodiment of the invention, the auxiliary outlet is close to one of the two end walls.

[0025] Preferably, the expression "in the vicinity of" means that at least one auxiliary inlet and / or outlet is at any point within a quarter of the wrap-around wall adjacent to one of the two end walls (along the main axis), i.e., at least one auxiliary inlet and / or outlet may be attached to one of the two end walls, or located at most 25% away from one of the two end walls.

[0026] According to an advantageous embodiment of the invention, the enveloping wall has a conicity angle between 0° and 50°.

[0027] According to an advantageous embodiment of the invention, the enveloping wall comprises a single conicity.

[0028] According to an advantageous embodiment of the invention, the enveloping wall comprises two opposing conicities, the auxiliary outlet being located at a boundary between the two conicities.

[0029] According to an advantageous embodiment of the invention, the at least one auxiliary inlet comprises an auxiliary inlet at each of the two axial ends of the enveloping wall.

[0030] According to an advantageous embodiment of the invention, at least 80% of a volume of the auxiliary enclosure is located in a lower half of the main enclosure, when the oil tank is oriented in a normal mounting position.

[0031] According to an advantageous embodiment of the invention, the enveloping wall has a principal axis coaxial with the channel or inclined at less than 45° with respect to said channel.

[0032] Preferably, the normal mounting position of the tank is one in which the main containment is located above the auxiliary containment in the direction of gravity (force perpendicular to the horizontal and directed downwards). To achieve this, the main containment, the auxiliary containment, and the channel may be inclined during mounting on the turbomachine or may have specific shapes. For example, the main containment is preferably substantially cylindrical, but may have a substantially oblong and / or curved shape.

[0033] The invention also relates to a hydraulic system for an aircraft turbomachine comprising: an oil reservoir; a turbomachine lubrication circuit, hydraulically connected to the oil reservoir; a hydraulic control circuit for at least one hydraulic actuator, hydraulically connected to the oil reservoir; remarkable in that the oil reservoir is, according to the invention, the lubrication circuit being hydraulically connected to the inlet of oil mixed with air and to the oil outlet, the hydraulic control circuit being hydraulically connected to at least one auxiliary inlet and to the auxiliary outlet.

[0034] The invention also relates to a turbomachine comprising: an unfaired propeller propelling an incoming airflow, said propeller comprising variable pitch blades actuated by at least one hydraulic actuator; a hydraulic system capable of providing lubrication of the turbomachine and of controlling at least one hydraulic actuator; remarkable in that the hydraulic system is according to the invention.

[0035] The invention also relates to a turbomachine comprising: an unfaired propeller propelling an incoming airflow, said propeller comprising a variable pitch system for actuating the pitch of the propeller blades; an oil reservoir for lubricating components of the turbomachine, notable in that said reservoir comprises: a main enclosure suitable for containing the oil; an oil-air mixed inlet, disposed on the main enclosure; an oil outlet, disposed on the main enclosure; an auxiliary enclosure disposed inside the main enclosure, comprising an enveloping wall, and two end walls adjacent to said enveloping wall, at least one of the two end walls comprising at least one oil passage with the interior of the main enclosure; at least one auxiliary inlet opening tangentially to a smaller diameter section of the enveloping wall and passing through the main enclosure for connection to an auxiliary circuit;an auxiliary outlet, tangential to a larger diameter section of the enclosing wall, said auxiliary outlet passing through the main enclosure for connection to the auxiliary circuit.

[0036] According to an advantageous embodiment of the invention, the variable pitch system is a first variable pitch system, and said turbomachine further comprises a rectifier comprising a plurality of stator blades extending from a fixed casing, said rectifier comprising a second variable pitch system, and in that the auxiliary output is hydraulically connected to a second closed circuit comprising components of the first system and / or the second variable pitch system of the turbomachine. Advantages of the invention

[0037] The invention is particularly advantageous in that it ensures a continuous oil supply to the various components of the turbomachine, including the hydraulic control system(s) of at least one hydraulic actuator, specifically the variable-pitch system(s), while guaranteeing that the latter (or these) are supplied with oil without any air presence and without interruption of supply during zero-gravity and negative-gravity flight phases. Thus, the hydraulic control of the turbomachine's propeller pitch control system can remain operational during all phases of aircraft flight.

[0038] Advantageously, the simple architecture of the oil reservoir in the present invention ensures reliable operation. Furthermore, the reservoir is compact, which reduces the overall size and mass of the turbomachine. Description of the drawings

[0039] [ Fig 1 ] is a schematic longitudinal cross-sectional view of an aircraft turbomachine according to the invention; [ Fig 2 ] illustrates a diagram of a hydraulic system, the turbomachine of the figure 1 ; Fig 3 ] represents a cross-sectional view of an oil tank according to a first embodiment of the invention during a flight phase of the aircraft in negative gravity; [ Fig 4 ] represents a cross-sectional view of an alternative to the oil reservoir of the figure 3 ; Fig 5 ] illustrates a cross-sectional view of a variant of an auxiliary containment structure for the reservoir of the figure 3 ; Fig 6 [ ] is a diagram of a top view of a wraparound wall of the oil tank of the figure 3 ; Fig 7 ] represents a cross-sectional view of an oil tank according to a second embodiment of the invention during a flight phase of the aircraft in negative gravity. Detailed description

[0040] The figures show the elements schematically and are not drawn to scale. In particular, some dimensions are enlarged to facilitate reading the figures.

[0041] There figure 1 schematically illustrates a longitudinal cross-sectional view of an aircraft turbomachine according to the invention. This is a turbomachine known by the English expression "open rotor" or "unducted fan", and particularly a USF "Unducted Single Fan" turbomachine.

[0042] In the description that follows, the terms "internal" and "external" refer to positioning relative to the axis of rotation of a turbomachine, and here along the longitudinal X-axis (and even from left to right on the figure 1The terms "radial," "internal," and "external" are defined with respect to a radial direction perpendicular to the longitudinal axis X. Upstream and downstream refer to the direction of flow within the turbomachine. Furthermore, elements illustrated in the figures that are identical or substantially identical and / or have the same functions are represented by the same numerical references.

[0043] The turbomachine 2 typically comprises, from upstream to downstream, a first compression stage, called a low-pressure compressor 4, as well as a second compression stage, called a high-pressure compressor 6, a combustion chamber 8 followed by a high-pressure turbine 9 and a low-pressure turbine 10.

[0044] The turbomachine 2 includes a propeller 14 arranged upstream of a separation nozzle 16 carried by an external casing 24 and capable of separating the airflow F into a secondary flow F2 and a primary flow F1 circulating in a primary channel 18 and passing through the various levels of the turbomachine 2 mentioned above.

[0045] The primary stream 18 is radially delimited by a radially internal wall 20 and a radially external wall 22. The radially internal wall 20 is supported by the internal casing 12. The radially external wall 22 is supported by the external casing 24. The primary airflow F1 enters the primary stream 18 through an annular air inlet 17 and exits through a primary nozzle 19 which is located downstream of said primary stream 18. The primary flow F1 can be accelerated by the primary nozzle 19 so as to generate a thrust reaction necessary for the flight of the aircraft.

[0046] The turbomachine comprises a rotating housing 26 centered on the longitudinal axis X and rotating about it. The rotating housing 26 carries a ring of movable blades 28 forming the propeller 14. The rotating housing 26 is mounted movable relative to the internal housing 12 that supports it.

[0047] The airflow F entering the turbomachine passes through the blades 28 of the propeller 14 to form the secondary airflow F2. This secondary airflow circulates around the outer casing 24. Each blade 28 of the propeller 14 comprises a foot 30 and an aerodynamic section extending radially outwards from the foot 30, the latter incorporating a pivot. The foot 30 is mounted to pivot about an axis A (perpendicular to X), thus allowing the blades 28 of the propeller 14 to pivot. This pivoting is controlled by a first variable pitch system of the turbomachine 2.

[0048] The low-pressure compressor 4 and the low-pressure turbine 10 are mechanically linked by a low-pressure shaft 11, the latter drives the propeller 14 via a reduction gear 32, the propeller 14 compresses the air outside the external casing 24 and provides most of the thrust of the turbomachine 2. The reduction gear 32 may be of the planetary gear type.

[0049] The turbomachine 2 includes a rectifier 34 through which the secondary flow F2 passes, the latter being a portion of the airflow F propelled radially outward from the longitudinal axis X. The rectifier 34 comprises a plurality of stator vanes 36 (or stator blades or fixed vanes) known by the English acronym "OGV" (Outlet Guide Vane). The stator vanes 36 are evenly distributed around the longitudinal axis X and extend radially into the secondary airflow F2. The stator vanes 36 are supported by a fixed structure integral with the outer casing 24. In particular, each stator vane 36 extends radially from a foot 38, the latter being pivotally mounted about an axis B (perpendicular to X), allowing the stator vanes 36 of the rectifier 34 to pivot. This pivoting is controlled by a second variable-pitch system of the turbomachine 2.

[0050] The turbomachine 2 further comprises an oil reservoir 40, 400 for the lubrication and / or cooling of the components of said turbomachine 2. For this purpose, the oil reservoir 40, 400 is the main oil reservoir of the turbomachine 2, and also supplies oil to the first and second variable timing systems of the turbomachine 2. Preferably, the reservoir 40, 400 is arranged adjacent to the external casing 24. The architecture and operation of the oil reservoir 40, 400 will be detailed later in this description.

[0051] Alternatively, the oil reservoir 40, 400 of the present invention is capable of supplying oil to a turbomachine comprising a variable pitch system only at the level of the rectifier (having a fixed-blade propeller without a variable pitch system).

[0052] There figure 2 is a diagram of a hydraulic system 39 the turbomachine of the figure 1The hydraulic system 39 comprises various closed circuits connected to the oil reservoir of the invention so as to ensure lubrication of the turbomachine. With reference to the figure 2 , the oil reservoir 40 is hydraulically connected to a lubrication and cooling circuit 42 of the turbomachine engine, this circuit includes a supply pump 43, heat exchangers 44 and engine enclosures 45, the latter ensure the lubrication of the bearings, reducers and bearings and ensure the air / oil sealing of the engine.

[0053] There figure 2 illustrates the reservoir 40 according to a first embodiment, but the hydraulic system 39 can also include an oil reservoir 400 according to a second embodiment illustrated in the figure 7 These two embodiments will be described in detail later in this description.

[0054] The lubrication circuit 42 further includes at least one recovery pump 46 configured to recover oil from the engine enclosures 45 and direct it to the oil reservoir 40. The circuit 42 may correspond to a turbomachine lubrication group.

[0055] The oil reservoir 40 is also hydraulically connected to a propeller blade pitch control circuit 48, also designated as a hydraulic control circuit 48, which supplies oil to the first variable pitch system of the turbomachine. figure 1 , namely propeller 14.

[0056] The hydraulic control circuit 48 can also supply oil to the second variable timing system of the turbomachine of the figure 1 , namely the rectifier 34, independently or in combination with the first variable timing system.

[0057] The hydraulic control circuit 48 can provide lubrication and / or cooling functions for the variable valve timing system. In this respect, the circuit 48 includes a lift pump 49 that draws oil from a lower portion of the reservoir 40 and directs it to a heat exchanger 50. More specifically, the lift pump 49 draws oil from an auxiliary chamber of the reservoir 40, which will be detailed later in this description.

[0058] Preferably, the hydraulic control circuit 48 is also configured to hydraulically control the variable pitch system in addition to the lubrication and cooling functions. In this respect, the circuit 48 includes a pitch actuation pump 51 that can hydraulically control a pitch actuation system or a hydraulic actuator 52, the latter being able to correspond to the first and / or second variable pitch system of the turbomachine.

[0059] In this configuration, the step actuation pump 51 actuates the hydraulic actuator 52, which causes the feet 30 and 38 to pivot. figure 1 .

[0060] Preferably, the hydraulic control circuit 48 includes a bypass valve 53 allowing the choice between a cooling function or actuation of the step of the variable pitch system.

[0061] The circuit 48 includes at least one oil return to the reservoir 40, 400, this oil return is preferentially accelerated by at least one of the pumps (49 and / or 51).

[0062] Advantageously, the hydraulic system 39 includes a connection (illustrated in dotted lines) between the hydraulic control circuit 48 and the lubrication circuit 42 to collect any leaks from the propeller pitch actuation cylinders and to reinject this oil into the reservoir 40 from an inlet 66.

[0063] There figure 3Figure 40 represents a cross-sectional view of an oil tank according to a first embodiment of the invention during a flight phase of the aircraft in negative G. Hereafter, G+ will refer to positive gravity and G- to negative gravity.

[0064] It should be noted that tank 40 is capable of ensuring a constant oil supply during G-force flight phases, each lasting between a fraction of a second and 45 seconds. Advantageously, tank 40 can be sized to ensure a constant oil supply even beyond 45 seconds.

[0065] In this respect, the oil reservoir 40 includes an oil inlet 66 containing oil mixed with air, leading to a main chamber 54 suitable for containing the oil, and specifically to an oil deaerator device 68, which allows the air 70 mixed with the oil at the oil inlet 66 to be evacuated. The oil inlet 66 preferably comes from at least one recovery pump 46 of the figure 2 .

[0066] The tank 40 includes an auxiliary enclosure 56 arranged inside the main enclosure 54, and includes a wrap-around wall 60 with two end walls 61, 63 adjacent to said wrap-around wall 60.

[0067] Advantageously, the arrangement of the auxiliary enclosure 56 inside the main enclosure 54 allows for a rapid exchange of oil flows between the two.

[0068] However, in an alternative (represented in the figure 4The auxiliary containment 56 is positioned externally to the main containment 54 so as to allow the tank 40' to be integrated into the particularly demanding environment of the turbomachine. In this respect, one or more hydraulic lines 62' can connect the two containments 54 and 56. In this configuration, the hydraulic line(s) 62' can be flexible and / or be combined with a channel 62.

[0069] We can see at the figure 4 that the main enclosure 54 of the reservoir 40' includes an end wall 61' corresponding to a bottom wall 61' of the main enclosure 54. The latter may advantageously have a conical shape so as to facilitate the circulation of oil towards the channel 62 during the return to G+.

[0070] With reference to the figure 3The enveloping wall 60 corresponds preferably to a conical circular wall 60 allowing to generate a circular and accelerated flow of the oil within the auxiliary enclosure 56. Such a flow will be detailed in the present description.

[0071] Alternatively, the enclosing wall 60 may have a different shape depending on the integration requirements and / or the operating conditions of the turbomachine. For example, the enclosing wall 60 may have a cylindrical or elliptical shape to facilitate the integration of the tank 40 in a more constrained environment.

[0072] The reservoir 40 also includes an oil outlet 72 preferably located at the end wall 63 in the auxiliary enclosure 56.

[0073] In this configuration, the oil inlet 66 and the oil outlet 72 form a circuit corresponding to the lubrication circuit 42 of the figure 2 .

[0074] Alternatively, the oil outlet 72 can also be located on a side wall of the main enclosure 54.

[0075] It is preferable for the outer wall 60 of the tank 40 to be fully formed with the main enclosure 54, as this saves space. However, it is possible for the outer wall 60 to be contained within the auxiliary enclosure 56 at a distance from the side walls of the auxiliary enclosure 56.

[0076] We can also see on the figure 3 that the two end walls 61, 63 are formed with the enveloping wall 60, but these walls 61 and 63 can also be at a distance from the enveloping wall 60 by being formed for example with side walls of the main enclosure 54.

[0077] The end wall 61 is an upper end wall 61, following the direction of gravity (perpendicular to the horizontal plane), and arranged in a larger diameter section 60.1 of the enveloping wall 60. Conversely, the end wall 63 is a lower end wall 63 arranged in a smaller diameter section 60.2 of the enveloping wall 60.

[0078] The upper end wall 61 includes an oil passage comprising a channel 62 extending axially (along a principal axis of said channel) within the auxiliary enclosure 56 and over at least 20% of the total axial extent of the auxiliary enclosure 56, and up to at least 99% of said total extent. This channel 62 allows the oil to reach the oil outlet 72 in G+. Preferably, the channel 62 extends over 30% to 95% of the total axial extent of the auxiliary enclosure 56, and more preferably over 30% to 70% of said axial extent.

[0079] Preferably, the channel 62 is in a central position of the upper end wall 61 and opposite the oil outlet 72. Advantageously, this allows the oil to quickly reach the outlet 72 during a return to G+ after G-.

[0080] In an alternative not shown, the upper end wall 61 may have a conical shape so as to facilitate the flow of oil towards the channel 62 during the return to G+.

[0081] Advantageously, channel 62 allows for the thermal expansion of the oil by utilizing the buffer volume (auxiliary chamber 56) of the main reservoir 40. Furthermore, channel 62 allows for reinjection into the auxiliary circuit (circuit 48 of the figure 2 ) the oil that is lost at the leaks of the propeller pitch actuation cylinders.

[0082] The reservoir 40 also includes an auxiliary inlet 67 passing through the main enclosure 54 and close to the lower end wall 63, this auxiliary inlet 67 opens tangentially into section 60.2.

[0083] The auxiliary inlet 67 corresponds to an oil return from the hydraulic control circuit 48 of the figure 2 Indeed, the auxiliary inlet 67 is configured to project the accelerated oil from the hydraulic control circuit towards the surrounding wall 60 in such a way as to generate a cyclonic motion or a circular flow of the oil 65 on the surrounding wall 60. Such a motion makes it possible to rotate all the oil in the auxiliary chamber in order to overcome gravity and reach an auxiliary outlet 74 during all phases of flight of the aircraft (G+ and G0 and G-).

[0084] Indeed, the oil sprayed onto the surrounding wall 60 preferentially has an acceleration of at least 3g (g being the acceleration due to gravity in m / s²) and can, for example, correspond to 6g. In fact, the acceleration of the oil sprayed at the auxiliary inlet 67 can exceed 6g depending on the need and operating conditions.

[0085] Similar to the auxiliary inlet 67, the auxiliary outlet 74 is also tangential to the enclosure wall 60, and specifically to the larger diameter section 60.1 of said wall 60. In this respect, the auxiliary outlet 74 passes through the main enclosure 54 in order to join the hydraulic control circuit 48 of the figure 1 .

[0086] Advantageously, each of the smaller diameter 60.2 and larger diameter 60.1 sections of the enveloping wall 60 corresponds to less than 50% of a total height H of the auxiliary enclosure 56, and preferentially corresponds to 25% of the height H.

[0087] In the configuration illustrated at the figure 3 , each of the auxiliary input 67 and auxiliary output 74 is adjacent to the corresponding end wall 61, 63.

[0088] However, the auxiliary output 74 can be placed closer to the auxiliary input 67 and vice versa.

[0089] Preferably, the cyclonic movement of the oil 65 on the surrounding wall 60 allows for an oil acceleration at the auxiliary outlet 72 of approximately 5g (in the example described). This value ensures a continuous oil supply to the hydraulic control circuit during all phases of aircraft flight.

[0090] The G- event illustrated in the figure 3 shows that the oil 65 remains pressed against the surrounding wall 60, this pressing can be achieved by a centrifugal force induced at least in part by an angle of conicity of the surrounding wall 60.

[0091] The enveloping wall 60 has a principal axis R corresponding to the principal direction of the extent of said wall 60. For this purpose, the principal axis R defines the direction of the largest dimension of the enveloping wall 60 (the height H).

[0092] Preferably, the main axis R is coaxial with channel 62, or inclined at less than 30° with respect to said channel 62. However, the inclination of the main axis R with respect to channel 62 may be up to 45° or exceed 45° to form an angle of less than 90° with channel 62.

[0093] Preferably, the principal axis R follows the direction of gravity (perpendicular to the horizontal). However, the principal axis R may be inclined with respect to the direction of gravity by an angle of up to 45° or exceeding 45° up to forming an angle of less than 90° with said direction of gravity.

[0094] Preferably, the wall 60 of the tank 40 has a single conicity identified by a conicity angle α between 0° (cylindrical wall 60) and 50°, and preferably between 20° and 45°, and even more preferably equal to 30°. The conicity angle α is shown between the enveloping wall 60 and the principal direction.

[0095] Furthermore, the upper end wall 61 may include a valve (not shown) or a flap sensitive to changes in gravity and allowing the oil to be kept in the auxiliary enclosure 56 in G- and to accelerate the return of oil into said enclosure in G+.

[0096] In addition, the upper end wall 61 may further include at least one vent (not shown) allowing air to be rapidly evacuated from the auxiliary enclosure 56 in order to allow a rapid return of oil to said auxiliary enclosure 56 during a return of the aircraft in G+ after G-.

[0097] The enclosure 54 may include a perforated baffle (not shown) arranged above the upper end wall 61 and allowing the oil to be filtered and purified before it reaches the auxiliary enclosure 56 in G+.

[0098] There figure 5 illustrates a cross-sectional view of a variant of enclosure 56 of the figure 3in which, at the end wall 63, the oil outlet 72 comprises a tube 73 extending into the channel 62 and concentrically to it. Advantageously, this allows prioritizing the filling of the auxiliary chamber 56 to ensure a continuous oil supply and rapid oil return to the outlet 72 during a return to G+ after G-.

[0099] There figure 6 is a diagram of a top view of the wraparound wall 60 of the oil tank of the figure 3 .

[0100] The tangential orientations of the auxiliary inlet 67 and the auxiliary outlet 74 are clearly distinguishable. Advantageously, this tangential orientation of the auxiliary inlet and outlet 67 and 74 limits friction that can occur between the viscous oil and the surrounding wall 60. Advantageously, this orientation maximizes the oil velocity on the surrounding wall 60, allowing the oil to follow the trajectory 50 that enables it to quickly reach the auxiliary outlet 74.

[0101] It is possible that the trajectory 50 can be defined by grooves formed in the enveloping wall 60.

[0102] There figure 7 represents a cross-sectional view of an oil tank 400 according to a second embodiment of the invention during a flight phase of the aircraft in G-.

[0103] Elements identical to those of the first embodiment are represented by the same numerical references, and elements with a difference will be represented with an increment of 100.

[0104] With reference to the figure 7 The tank 400 includes a wrap-around wall 160 having two opposing conicities. In this configuration, the wrap-around wall 160 comprises two sections of smaller diameter 160.2, each comprising an upper end wall 161 and a lower end wall 163, and a section of larger diameter 160.2 corresponding to a boundary between the two conicities, said boundary 160.2 being preferably without a wall.

[0105] The surrounding wall 160 delimits an auxiliary enclosure 156 inside the main enclosure 54. For this purpose, at least 80% of a volume of the auxiliary enclosure 156 is inside the main enclosure, and preferably, the entire volume of the auxiliary enclosure 156 is inside the main enclosure 54.

[0106] Preferably, the wraparound wall 160 is integrally formed with the enclosure 54. To this end, said wall 160 is connected to the enclosure by means of rigid tubes 67.1 and 74.1, which respectively form the auxiliary inlet 67 and outlet 74. However, these tubes 67.1 and 74.1 may be flexible, and the wraparound wall 160 may be rigidly connected to the enclosure by means of the end wall 161 and / or 163, which may extend to a side wall of the enclosure 54. For this purpose, internal stiffeners (not shown) may rigidly connect the wraparound wall 160 to the main enclosure 54.

[0107] Preferably, each of the two end walls 161 and 163 includes the channel 62, the latter here ensuring a passage of oil between the auxiliary enclosure 156 and the main enclosure 54.

[0108] The G- event illustrated in the figure 7 shows that the oil has a trajectory 50 from each of the two auxiliary inlets 67 and this, up to the auxiliary outlet 74 which recovers the oil having an acceleration of about 5g at the level of the boundary 106.2.

[0109] Advantageously, the reservoir 400 according to the second embodiment, allows a combination of two cyclonic movements within the auxiliary enclosure 156, this combination makes it possible to avoid variations in the volume of accelerated oil and to avoid variations in acceleration, thus the oil in the auxiliary enclosure 156 is able to easily reach the acceleration of 5g in the direction of the hydraulic control circuit.

[0110] Preferably, the tank 40 according to the first embodiment or the tank 400 according to the second embodiment of the present invention is obtained by additive manufacturing.

[0111] Advantageously, the turbomachine of the present invention is capable of ensuring continuous and secure operation of its variable pitch systems thanks to the main oil reservoir which provides oil priming to supply such systems with oil without any presence of air and without interruption of supply during flight phases in zero or negative gravity.

Claims

1. An oil tank (40; 400) for an aircraft turbomachine (2), comprising: - a main chamber (54) adapted to contain the oil; - an oil inlet (66) for oil mixed with air, disposed on the main chamber (54); - an oil outlet (72); - an auxiliary chamber (56; 156) comprising an enclosing wall (60; 160), and two end walls (61, 63; 161, 163) adjacent to said enclosing wall (60), at least one of the two end walls (61, 63; 161, 163) comprising at least one oil passage (62) communicating with the interior of the main chamber (54), characterized in that the oil tank (40; 400) further comprises - at least one auxiliary inlet (67) opening tangentially to the enclosing wall (60; 160) and passing through the auxiliary chamber (56; 156) for connection to an auxiliary circuit (48); - an auxiliary outlet (74), tangential to a larger diameter section (60.1; 160.1) of the enclosing wall (60; 160), said auxiliary outlet (74) passing through the auxiliary chamber (56; 156) for connection to the auxiliary circuit (48), the oil outlet (72) being disposed on the auxiliary chamber (56) or on the main chamber (54).

2. The oil tank (40; 400) according to claim 1, in which the enclosing wall (60; 160) is integrally formed with the main chamber (54), and said enclosing wall (60; 160) preferably comprises a conical circular shape.

3. The oil tank (40; 400) according to claim 2, in which the at least one auxiliary inlet (67) opens tangentially to a smaller diameter section (60.2; 160.2) of the enclosing wall (60; 160).

4. The oil tank (40; 400) according to any one of claims 1 to 3, in which the at least one oil passage (62) is centrally positioned on the corresponding end wall (61; 161, 163).

5. The oil tank (40; 400) according to any one of claims 1 to 4, in which the at least one oil passage (62) comprises a channel (62) extending axially from the corresponding end wall (61; 161, 163) to the interior of the auxiliary chamber (56; 156).

6. The oil tank (40; 400) according to claim 5, in which the at least one channel (62) extends over at least 30% or 20% of a total axial extent of the auxiliary chamber (56; 156).

7. The oil tank (40; 400) according to any one of claims 1 to 6, in which the at least one auxiliary inlet (67) is proximate to one of the two end walls (63; 161, 163).

8. The oil tank (40) according to any one of claims 1 to 7, in which the auxiliary outlet (74) is proximate to one of the two end walls (61).

9. The oil tank (40; 400) according to any one of claims 1 to 8, in which the enclosing wall (60; 160) has a conicity angle (a) between 0° and 50°.

10. The oil tank (40) according to any one of claims 1 to 9, in which the enclosing wall (60) has a single conicity.

11. The oil tank (400) according to any one of claims 1 to 10, in which the conical circular enclosing wall (160) has two opposed conicities, the auxiliary outlet (74) being located at a border (160.1) between the two conicities.

12. The oil tank (400) according to claim 10, in which the at least one auxiliary inlet (67) comprises an auxiliary inlet (67) at each of the two axial ends (161, 163) of the conical circular enclosing wall (160).

13. The oil tank (40; 400) according to any one of claims 1 to 11, in which at least 80% of a volume of the auxiliary chamber (56; 156) is located in a lower half of the main chamber (54) when the oil tank (40; 400) is oriented in a normal mounting position.

14. The oil tank (40; 400) according to any one of claims 1 to 13, in which the enclosing wall (60; 160) has a main axis (R) coaxial with the channel (62) or inclined by less than 45° relative to said channel (62).

15. A hydraulic system (39) for an aircraft turbomachine (2) comprising: - an oil tank (40; 400); - a lubrication circuit (42) of the turbomachine (2), hydraulically connected to the oil tank (40; 400); - a hydraulic control circuit (48) of at least one hydraulic actuator (52), hydraulically connected to the oil tank (40; 400); characterized in that the oil tank (40; 400) is according to any one of claims 1 to 14.

16. The hydraulic system (39) according to claim 15, in which the lubrication circuit (42) is hydraulically connected to the oil inlet (66) for oil mixed with air and to the oil outlet (72), the hydraulic control circuit (48) being hydraulically connected to the at least one auxiliary inlet (67) and to the auxiliary outlet (74).

17. An aircraft turbomachine (2) comprising: - an uncowled propeller (14) propelling an incoming air flow (F), said propeller (14) comprising variable pitch blades (28) actuated by at least one hydraulic actuator (52); - a hydraulic system (39) capable of ensuring lubrication of the turbomachine (2) and controlling the at least one hydraulic actuator (52); characterized in that the hydraulic system (39) is according to any one of claims 15 or 16.