AIR INLET FOR AN AIRCRAFT PROPULSION UNIT WITH AN ELEMENT FOR MOVING A MOVABLE PRE-PROCESSED PART AND METHOD FOR USE SUCH AN AIR INLET

Description

Domaine technique

[0001] The present invention relates to the field of air inlets for aircraft propulsion systems comprising a movable upstream part.

[0002] As is well known, it is represented on the [ Fig.1A ] an aircraft propulsion assembly 108 extending along a longitudinal axis X oriented from upstream to downstream and comprising a turbomachine 106 and a nacelle 107. The turbomachine 106 extends along the longitudinal axis X and is configured to enable propulsion of the aircraft from the acceleration of an interior air flow F-INT circulating from upstream to downstream in the turbomachine 106. The nacelle 107 extends externally in a peripheral manner around the turbomachine 106 along the longitudinal axis X and enables the interior air flow F-INT to be guided in the turbomachine 106. Subsequently, the terms “upstream” and “downstream” are defined with respect to the orientation of the longitudinal axis X. Unless otherwise indicated, the terms “interior” and “exterior” are defined in the radial direction with respect to the longitudinal axis X. It is also specified that the interior air flow F-INT denotes the mass flow of air admitted into the nacelle 107.

[0003] As known, with reference to the [ Fig.1A ] and the [ Fig.1B ], the nacelle 107 comprises at its upstream end a variable geometry air inlet 105 so as to adapt the internal air flow F-INT guided in the turbomachine 106 according to the flight conditions. More precisely, in a known manner, the air inlet 105 comprises a movable upstream part 101, a fixed downstream part 102 and linear cylinders 103 mounted in the fixed downstream part 102 and equally distributed around the circumference of the air inlet 105. The linear cylinders 103 are configured to move together the movable upstream part 101 in translation along the longitudinal axis X relative to the fixed downstream part 102 between a retracted position P1 ([ Fig.1A ]), in which the movable upstream part 101 is adjacent to the fixed downstream part 102, and an output position P2 ([ Fig.1B ]), in which the movable upstream part 101 is spaced from the fixed downstream part 102.

[0004] In a known manner, as illustrated in the [ Fig.1A ] and the [ Fig.1B ], the movable upstream part 101 comprises an upstream inner wall 110 facing the longitudinal axis X and an upstream outer wall 111 opposite the upstream inner wall 110, which are connected together upstream by an air inlet lip 112 comprising a leading edge. The movable upstream part 101 thus comprises an aerodynamic rounded profile which makes it possible to separate an upstream air flow F into the interior air flow F-INT guided by the upstream inner wall 110 and an exterior air flow F-EXT guided by the upstream outer wall 111. The fixed downstream part 102 comprises a downstream interior wall 120 and a downstream exterior wall 121 which extend respectively in the downstream continuity of the upstream interior wall 110 and the upstream exterior wall 111 of the movable upstream part 101 in the retracted position P1.In the output position P2, the movable upstream part 101 and the fixed downstream part 102 are spaced apart by a through channel 104 for fluid circulation between the exterior air flow F-EXT and the interior air flow F-INT.

[0005] In practice, it is known to use such a variable geometry air inlet 105 for a supersonic aircraft propulsion unit, namely one whose turbomachine 106 is configured to enable propulsion of the aircraft up to speeds greater than the speed of sound. Indeed, the air inlet 105 in the retracted position P1 enables air intake suitable for high subsonic speeds, i.e. Mach numbers greater than 0.5, and for supersonic speeds. The extended position P2 allows the cross-section of the air inlet 105 and therefore the admitted internal air flow F-INT to be increased, which makes it suitable for low subsonic speeds, i.e. Mach numbers less than 0.5. This makes it possible to control the internal air flow F-INT admitted into the turbomachine 106.

[0006] In fact, such an air inlet 105 with variable geometry has the disadvantage of increasing the size and the on-board mass of the aircraft. In particular, the linear cylinders 103 used, traditionally hydraulic, pneumatic or electric, are numerous, heavy and occupy a large volume in the fixed downstream part 102. Such linear cylinders are complex to integrate into an air inlet 105 of small thickness. In addition, controlling the movement of the mobile upstream part 101 requires synchronizing the linear cylinders 103, which is complex.

[0007] An air inlet according to the prior art is disclosed in document US2020 / 386158 A1.

[0008] In the remote field of vertical take-off aircraft, application US3058693A1 discloses an air inlet with an upstream part that can move in translation by means of a screw driven by the rotation of a nut. Such an air inlet has the same drawbacks as described previously.

[0009] In the remote field of aircraft maintenance, application US20100084507A1 discloses an air inlet with a movable upstream part to facilitate, on the ground, access to the various equipment and / or their replacement.

[0010] The invention thus aims to eliminate at least some of these drawbacks. PRESENTATION DE L'INVENTION

[0011] The invention relates to an air intake for an aircraft propulsion unit, said aircraft propulsion unit extending along a longitudinal axis oriented from upstream to downstream and comprising a turbomachine configured to enable propulsion of the aircraft from the acceleration of an internal air flow circulating from upstream to downstream in the turbomachine, said air intake extending circumferentially around the longitudinal axis and comprising a movable upstream part, a fixed downstream part and at least one displacement member configured to move the movable upstream part in translation relative to the fixed downstream part, said movable upstream part comprising: an upstream inner wall, facing the longitudinal axis and configured to guide the inner air flow, an upstream outer wall, opposite the upstream inner wall and configured to guide an outer air flow, and an air inlet lip connecting the upstream inner wall and the upstream outer wall, said movable upstream part being movable between a retracted position, in which the movable upstream part is adjacent to the fixed downstream part, and an extended position, in which the movable upstream part is spaced upstream of the fixed downstream part so as to delimit between them a through channel for fluid circulation between the outer air flow and the inner air flow.

[0012] The invention is remarkable in that the displacement member comprises: at least one guide bar connected to the movable upstream part, and a drive bar comprising a plurality of teeth, the fixed downstream part comprising, for each displacement member: a toothed wheel configured to be driven in rotation and to cooperate with the teeth of the drive bar so as to form a rack and pinion connection making it possible to move the displacement member and the movable upstream part, and at least one guide member configured to guide the guide bar during the movement of the displacement member.

[0013] It is specified that the term "bar" is used throughout the application to describe a long, rigid piece of any cross-section, such as circular, square, rectangular or flattened, as non-exhaustive examples.

[0014] Thanks to the invention, the movable upstream part of a variable geometry air intake can advantageously be moved in a precise, durable and practical manner thanks to a rack and pinion connection integrated into the fixed downstream part and guided in translation. The movement of the movable upstream part makes it possible to modify in flight the internal air flow admitted into the air intake and thus adapt to different speeds of the aircraft, such as the transition to supersonic speeds for example. The rack and pinion connection has the advantage, compared to the linear actuators traditionally used, of being more robust and economical while offering great precision. The guide members also make it possible to force the movable upstream part to move in a given longitudinal direction, avoiding any deviation or variability, which increases the reliability of the rack and pinion connection.

[0015] Preferably, the displacement member is configured to move the movable upstream part in substantially longitudinal translation relative to the fixed downstream part, in other words in a direction forming an angle of at most 20° relative to the longitudinal axis.

[0016] Preferably, the guide member is configured to form a sliding connection with the displacement member.

[0017] According to one aspect of the invention, the movable upstream part extends circumferentially around the longitudinal axis to act globally and homogeneously on the admission of the interior air flow. Preferably, the movable upstream part forms a unitary assembly, which facilitates its movement. Preferably, the movable upstream part forms a single-piece assembly.

[0018] Preferably, the air inlet comprises a plurality of displacement members so as to form a plurality of rack and pinion connections. The rack and pinion connection advantageously makes it easier to synchronize the displacement members and thus to move the movable upstream part quickly and easily. Preferably, the air inlet comprises a plurality of guide bars equally distributed around the circumference of the air inlet to distribute the forces applied to the movable upstream part and thus promote its movement.

[0019] According to a preferred aspect of the invention, the upstream inner wall and the upstream outer wall of the movable upstream part have a substantially identical longitudinal length. It is specified that the term "substantially" indicates here that the length of the upstream inner wall varies by at most 10% compared to that of the upstream outer wall. The movable upstream part and the fixed downstream part thus cooperate in a simple and practical manner in the retracted position. In the extended position, the through channel advantageously makes it possible to significantly increase the air inlet section and therefore the admitted interior air flow, as well as to reduce the noise generated.

[0020] According to one aspect of the invention: the drive bar extends in the downstream extension of the guide bar and comprises an outer wall comprising an angular drive portion, where the teeth are mounted, and an angular guide portion, and at least one guide member is in the form of a downstream guide member configured to successively guide the guide bar and the angular guide portion of the drive bar.

[0021] Advantageously, this makes it possible to reduce the size and the on-board mass of the displacement member, in particular the longitudinal length of the guide bar by allowing the same guide member to guide the guide bar and the drive bar.

[0022] According to one aspect of the invention, the angular guide portion extends over at least 120° of the outer wall of the drive bar. Preferably, the angular guide portion extends over more than 180° of the outer wall of the drive bar, and preferably, over at most 330° of the outer wall of the drive bar. At least semi-peripheral guidance of the drive bar advantageously makes it possible to precisely control the trajectory of the movable upstream part. This guarantees the robustness and durability of the displacement member without disturbing the rack and pinion connection.

[0023] According to one aspect of the invention, the angular drive portion comprises a recessed area in which the teeth are mounted. Such mounting of the teeth in a recess makes it possible to limit their bulk. Preferably, the teeth are mounted in the recessed area so as to extend radially inside the angular guide portion relative to the axis of the displacement member. In other words, the drive bar comprises a cross-section, including the teeth, which is included in a cross-section of the guide bar. The size and shape of the drive bar are thus less than or equal to those of the guide bar, so that a guide member suitable for the guide bar is also suitable for the drive bar.

[0024] According to a first aspect of the invention, the downstream guide member extends peripherally around the displacement member. This allows optimal guidance, namely precise and fine control of the direction of movement of the displacement member, without deviation or variability, which increases its longevity.

[0025] According to another aspect of the invention, the downstream guide member extends partially peripherally around the displacement member so as to avoid the annular drive portion and not restrict the rack and pinion connection.

[0026] According to one aspect of the invention, at least one displacement member comprises a plurality of guide bars and a connecting element configured to connect the drive bar to each guide bar. This makes it possible to limit the number of displacement members, and in particular the number of drive bars, which reduces the size and the on-board mass.

[0027] According to a preferred aspect of the invention, at least one guide member is in the form of at least one upstream guide member fixed to an upstream end of the fixed downstream part. Preferably, the upstream guide member extends peripherally around the guide bar. Such an upstream guide member protects the displacement member in an area subject to turbulence and vibrations.

[0028] The invention also relates to an aircraft propulsion assembly extending along a longitudinal axis oriented from upstream to downstream and comprising a turbomachine configured to enable propulsion of the aircraft from the acceleration of the internal air flow circulating from upstream to downstream in the turbomachine, said aircraft propulsion assembly comprising an air inlet as described previously.

[0029] Preferably, the turbomachine is supersonic, in other words configured to reach speeds greater than the speed of sound. The retracted position of the air inlet is advantageously suitable for high subsonic speeds, i.e. Mach numbers greater than 0.5, and supersonic speeds of the turbomachine. The extended position is suitable for low subsonic speeds, i.e. Mach numbers less than 0.5.

[0030] The invention further relates to a method for using in flight an air intake of an aircraft propulsion unit as described previously, in which the toothed wheel is driven in a first direction of rotation to move the movable upstream part in a first direction of translation oriented from the extended position to the retracted position, so as to reduce the flow of internal air admitted.

[0031] Another aspect of the invention, not claimed, also relates to a method of using in flight an air intake of an aircraft propulsion unit as described previously, in which the toothed wheel is driven in a second direction of rotation, opposite to the first direction of rotation, to move the movable upstream part in a second direction of translation, opposite to the first direction of translation, oriented from the retracted position to the extended position, so as to increase the flow of internal air admitted.

[0032] Advantageously, such a variable geometry air inlet makes it possible to modify the flow of internal air admitted by simply rotating the toothed wheel, during a change of speed of the aircraft propulsion unit. The transition from the retracted position to the extended position and vice versa is advantageously simple, quick and practical to implement.

[0033] Another aspect of the invention, not claimed, also relates to a method of using an aircraft propulsion unit in flight, in which, when the speed generated by the turbomachine is greater than a threshold speed, the toothed wheel is driven in a first direction of rotation to move the movable upstream part in a first direction of translation oriented from the extended position to the retracted position, so as to reduce the flow of internal air admitted.

[0034] Another aspect of the invention, not claimed, further relates to a method of using an aircraft propulsion unit in flight, in which, when the speed generated by the turbomachine is lower than a threshold speed, the toothed wheel is driven in a second direction of rotation, opposite to the first direction of rotation, to move the movable upstream part in a second direction of translation, opposite to the first direction of translation, oriented from the retracted position to the extended position, so as to increase the flow of internal air admitted.

[0035] Preferably, the threshold speed corresponds to a Mach number substantially equal to 0.5, to within plus or minus 20%. Such a threshold speed makes it possible to distinguish, on the one hand, low subsonic speeds requiring a large-section air inlet, and on the other hand, high subsonic speeds and supersonic speeds requiring a smaller-section air inlet.

[0036] Advantageously, such a variable geometry air inlet is particularly practical for a supersonic aircraft propulsion system, in which the generated speeds are both subsonic and supersonic. A simple rotation of the toothed wheel advantageously allows the intake of the internal airflow to be controlled simply, quickly and conveniently. PRESENTATION DES FIGURES

[0037] 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. There [ Fig.1A ] and The [ Fig.1B ] are schematic representations in longitudinal half-section of an aircraft propulsion unit comprising an air intake according to the prior art with a movable upstream part respectively in the retracted position and in the extended position; The [ Fig.2A ] and The [ Fig.2B ] are schematic representations in longitudinal half-section of an aircraft propulsion unit comprising an air intake according to an embodiment of the invention with a movable upstream part respectively in the retracted position and in the extended position according to an embodiment of the invention; The [ Fig.3 ] is a close-up schematic representation of the air inlet in the outlet position of the [ Fig.1B ] ; There [ Fig.4A ] and The [ Fig.4B ] are schematic representations in longitudinal half-section of the air inlet according to another embodiment of the invention respectively in the retracted position and in the extended position; The [ Fig.5A ] is a schematic perspective representation of the air inlet displacement member in the outlet position of the [ Fig.4B ] ; There [ Fig.5B ] is a schematic cross-sectional representation of the moving member of the [ Fig.5A ] ; There [ Fig.5C ] is a schematic cross-sectional representation of a displacement member according to an alternative embodiment of the invention; The [ Fig.6A ] is a schematic perspective representation of the displacement member according to another embodiment of the invention; The [ Fig.6B ] is a schematic cross-sectional representation of the moving member of the [ Fig.6A ] ; There [ Fig.6C ] is a schematic cross-sectional representation of a displacement member according to an alternative embodiment of the invention; The [ Fig.7A ], There [ Fig.7B ] and The [ Fig.7C ] are schematic representations in longitudinal section of a displacement member according to three other embodiments of the invention; The [ Fig.8 ] is a schematic perspective representation of the air inlet in the outlet position according to an alternative embodiment of the invention; and The [ Fig.9 ] is a schematic representation of the method of using the air inlet according to one embodiment of the invention.

[0038] 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 where appropriate. DESCRIPTION DETAILLEE DE L'INVENTION

[0039] With reference to the [ Fig.2A ] and as described in the preamble, the invention relates to an aircraft propulsion assembly 8 extending along a longitudinal axis X oriented from upstream to downstream and comprising a turbomachine 6 and a nacelle 7. The turbomachine 6 extends along the longitudinal axis X and is configured to enable propulsion of the aircraft from the acceleration of an interior air flow F-INT circulating from upstream to downstream in the turbomachine 6. The nacelle 7 extends externally in a peripheral manner around the turbomachine 6 along the longitudinal axis X and makes it possible to guide the interior air flow F-INT in the turbomachine 6. Subsequently, the terms “upstream” and “downstream” are defined with respect to the orientation of the longitudinal axis X. Unless otherwise indicated, the terms “interior” and “exterior” are defined in the radial direction with respect to the longitudinal axis X.It is also specified that the interior air flow F-INT designates the mass flow of air admitted into the nacelle 7.

[0040] With reference to the [ Fig.2A ] and the [ Fig.2B ] and as described in the preamble, the nacelle 7 comprises at its upstream end a variable geometry air inlet 5 so as to adapt the internal air flow F-INT guided in the turbomachine 6 according to the flight conditions. More precisely, in a known manner, the air inlet 5 comprises a movable upstream part 1, a fixed downstream part 2 and displacement members 3 mounted in the fixed downstream part 2 and configured to move the movable upstream part 1 in translation relative to the fixed downstream part 2 between: a retracted position P1 ([ Fig.2A ]), in which the mobile upstream part 1 is adjacent to the fixed downstream part 2, and an output position P2 ([ Fig.2B ]), in which the mobile upstream part 1 is spaced upstream from the fixed downstream part 2.

[0041] As illustrated in the [ Fig.2A ], there [ Fig.2B ] and the [ Fig.3 ] and described in the preamble, the movable upstream part 1 comprises an upstream inner wall 10 facing the longitudinal axis X and an upstream outer wall 11 opposite the upstream inner wall 10, which are connected together upstream by an air inlet lip 12 comprising a leading edge. The movable upstream part 1 thus comprises an aerodynamic rounded profile which makes it possible to separate an upstream air flow F into the interior air flow F-INT guided by the upstream interior wall 10 and an exterior air flow F-EXT guided by the upstream exterior wall 11. The fixed downstream part 2 comprises a downstream interior wall 20 and a downstream exterior wall 21 ([ Fig.3 ]) which extend respectively in the downstream continuity of the upstream inner wall 10 and the upstream outer wall 11 of the movable upstream part 1 in the retracted position P1. In the extended position P2, the movable upstream part 1 and the fixed downstream part 2 together delimit a through channel 4 for fluid circulation between the external air flow F-EXT and the internal air flow F-INT.

[0042] In the example of the [ Fig.3 ], the movable upstream part 1 comprises a downstream end 13 which delimits together with the upstream inner wall 10, the upstream outer wall 11 and the air inlet lip 12, an annular cavity 14 of longitudinal axis X. The movable upstream part 1 extends circumferentially around the longitudinal axis X. Preferably, the movable upstream part 1 forms a unitary assembly, preferably in one piece, namely made from the same material.

[0043] Still in the example of the [ Fig.3 ], the fixed downstream part 2 comprises an upstream end 22 connecting the downstream inner wall 20 and the downstream outer wall 21, which cooperates by complementary shapes with the downstream end 13 of the movable upstream part 1 in the retracted position P1, and delimits the through channel 4 with the downstream end 13 when the movable upstream part 1 is in the extended position P2. In this example, the upstream inner wall 10 and the upstream outer wall 11 have an identical length to facilitate cooperation. Still in this example, the downstream end 13 of the movable upstream part 1 and the upstream end 22 of the fixed downstream part 2 extend substantially transversely with respect to the longitudinal axis X in order to cooperate in a simple and practical manner by contact. The through channel 4 therefore extends substantially transversely with respect to the longitudinal axis X. Preferably, as illustrated in the [ Fig.3 ], the downstream end 13 of the movable upstream part 4 is concave and the upstream end 22 of the fixed downstream part 2 is convex, so that the through channel 4 is curved and allows aerodynamic fluid circulation without a sudden change of direction.

[0044] By way of example, it is known to use a variable geometry air inlet 5 for a supersonic aircraft propulsion unit, namely one whose turbomachine 6 is configured to enable propulsion of the aircraft up to speeds greater than the speed of sound. Indeed, the air inlet 5 in the retracted position P1 enables air intake suitable for high subsonic speeds, i.e. Mach numbers greater than 0.5, and supersonic speeds. The extended position P2 enables the cross-section of the air inlet 5 and therefore the internal airflow F-INT admitted to be increased for low subsonic speeds, i.e. Mach numbers less than 0.5. It goes without saying that the invention is not limited to the supersonic context and applies to any aircraft propulsion unit for which it is desired to modify the internal airflow F-INT intake in flight to adapt to the flight conditions.The retracted position P1 and the extended position P2 allow in particular the admission of the internal air flow F-INT into a subsonic aircraft propulsion unit to be controlled.

[0045] Preferably, the air inlet 5 has an elongated shape suitable for a subsonic and / or supersonic aircraft propulsion unit. According to one aspect, the air inlet 5 also has an air inlet cone to maintain a subsonic F-INT internal air flow in the turbomachine 6 at supersonic speeds of the aircraft.

[0046] According to the invention, with reference to the [ Fig.2A ], there [ Fig.2B ] and the [ Fig.3 ], each displacement member 3 comprises one or more guide bars 30 connected to the movable upstream part 1, and a drive bar 33 comprising a plurality of teeth 34.

[0047] Still according to the invention, the fixed downstream part 2 comprises, for each displacement member 3: a toothed wheel 24 configured to be driven in rotation and to cooperate with the teeth 34 of the drive bar 33 so as to form a rack and pinion connection making it possible to move the displacement member 3 and the movable upstream part 1, and one or more guide members 25 configured to guide the guide bar(s) 30 during the movement of the displacement member 3.

[0048] Preferably as shown in the [ Fig.2A ], there [ Fig.2B ] and the [ Fig.3 ], the displacement member 3 makes it possible to move the movable upstream part 1 in substantially longitudinal translation, namely in a direction forming an angle of at most 20° with the longitudinal axis X. Also preferably, each guide member 25 forms a sliding connection with the displacement member 3, in the substantially longitudinal direction of movement.

[0049] In the example of the [ Fig.2A ], there [ Fig.2B ] and the [ Fig.3 ], a single displacement member 3 is shown but, preferably, several displacement members 3 are distributed around the circumference of the air inlet 5 to distribute the forces applied to the movable upstream part 1 and facilitate its movement. Preferably, the air inlet 5 comprises at least three displacement members 3, and preferably at most eight for easy movement without significantly increasing the mass and bulk generated. Also preferably, the displacement members 3 are equally distributed around the circumference of the air inlet 5. It goes without saying that the invention also applies to a different distribution and / or number of displacement members 3. Several embodiments are described below, considering a single displacement member 3. Preferably, all the displacement members 3 are identical.Alternatively, the air inlet 5 comprises displacement members 3 according to several different embodiments.

[0050] In the embodiment illustrated in the [ Fig.3 ], the displacement member 3 comprises a single guide bar 30 comprising an upstream end 31 fixed to the movable upstream part 1, preferably at the downstream end 13 of the movable upstream part 1. When the movable upstream part 1 is retracted P1, the guide bar 30 extends into an annular cavity 23 of the fixed downstream part 2, delimited by the downstream inner wall 20, the upstream end 22 and the downstream outer wall 21. When the movable upstream part 1 is extended P2, the guide bar 30 also extends into the through channel 4.

[0051] In this example, the guide bar 30 is guided by a single guide member 25 mounted in the annular cavity 23 of the fixed downstream part 2, more precisely in the vicinity of the upstream end 22 to allow precise guidance. Preferably, other guide members 25 are mounted downstream to reinforce the precision of the guidance of the displacement member 3. A displacement member 3 guided by several guide members 25 is advantageously more robust and durable. However, it goes without saying that the number and position of the guide members 25 could be different.

[0052] Also preferably, the guide member 25 provides peripheral guidance, namely overall guidance over the entire periphery of the guide bar 30, and is presented, for example, in the form of a bearing or a ball bushing. Alternatively, the guide member 25 provides partially peripheral guidance, namely localized on an angular portion of the periphery of the guide bar 30, and is presented, for example, in the form of a rail, rollers or wheels. The guide members 25 may be of identical or different shape from one displacement member 3 to another and along the same displacement member 3. The guide members 25 and / or the guide bar 30 are preferably lubricated to promote the sliding connection.

[0053] Still referring to the [ Fig.3 ], the drive bar 33 extends in the annular cavity 23 of the fixed downstream part 2, in the downstream continuity of the guide bar 30. Preferably, the drive bar 33 and the guide bar 30 form the same part made from the same material. In this example, the displacement member 3 thus extends in a rectilinear manner and substantially along the longitudinal axis X. The toothed wheel 24 is mounted to rotate about a fixed axis transverse to the longitudinal axis X and comprises teeth which cooperate with the teeth 34 of the drive bar 33 so as to move the drive bar 33 in translation and consequently the displacement member 3.

[0054] The embodiment illustrated in the [ Fig.4A ] and the [ Fig.4B ] differs from the previous form in that the air inlet 5 comprises two guide members 25', 25", namely an upstream guide member 25' and a downstream guide member 25", and that the downstream guide member 25" is also configured to guide the drive bar 33. As illustrated in the [ Fig.4A ] and the [ Fig.4B ], the upstream guide member 25' extends in the vicinity of the upstream end 22 and is configured to guide the guide bar 30 as well as the guide member 25 of the [ Fig.3 ]. The downstream guide member 25" extends downstream of the upstream guide member 25' so as to successively guide the guide bar 30 and the drive bar 33 during a movement of the movable upstream part 1. In practice, the downstream guide member 25" is in contact with the guide bar 30 in the retracted position P1 ([ Fig.4A ]) and the drive bar 33 in the output position P2 ([ Fig.4B ]). When the upstream movable part 1 is extended P2, the downstream guide member 25" thus guides the guide bar 30 then the drive bar 33, and vice versa when the upstream movable part 1 is retracted P1. Such successive guidance makes it possible to increase stability during movement and improves the absorption of forces. This also makes it possible to reduce the length of the guide bar 30 and therefore to reduce overall the mass and size of the movement member 3.

[0055] In the example of the [ Fig.5A ] representing a close-up view of the [ Fig.4B ], the guide members 25', 25" are in the form of ball bushings or bearings. The drive bar 33 comprises an angular drive portion 36 where the teeth 34 are located and an angular guide portion 37 without teeth 34 and configured to cooperate with the downstream guide member 25". In other words, the angular drive 36 and guide 37 portions each extend over the entire length of the drive bar 33 in a partially peripheral and complementary manner. The downstream guide member 25" thus cooperates with the angular guide portion 37 while the toothed wheel 24 cooperates with the angular drive portion 36, without interference or hindrance.

[0056] More specifically, as illustrated in the [ Fig.5B ], the angular drive portion 36 extends in this example at an angle α36 of approximately 60° while the angular guide portion 37 extends in a complementary manner at an angle α37 of approximately 300°. Preferably, the angular guide portion 37 extends at an angle α37 greater than 120°, preferably greater than 180°, in particular in the case of a ball bushing or a bearing, to ensure sufficient and precise guidance. Also preferably, the angle α37 is less than 330° to allow the teeth 34 to be driven without hindrance.

[0057] As illustrated in the [ Fig.5A ] and the [ Fig.5B ], the angular guide portion 37 preferably extends in the longitudinal extension of the guide bar 30 to promote the continuity of the guidance. Thus, in this example, the guide bar 30 has a cylindrical outer wall 32 of circular section and the drive bar 33 has an outer wall 35 also cylindrical of circular section of the same diameter. As previously, the guide bar 30 and the drive bar 33 form the same part made from the same material. Still in this example, the teeth 34 are mounted projecting from the outer wall 35 of the drive bar 33 and the downstream guide member 25" extends in a partially peripheral manner around the displacement member 3, namely only around the angular guide portion 37. The angular opening of the downstream guide member 25" is less than or equal to the angle α37 of the angular guide portion 37.Thus, the downstream guide member 25" ensures partial angular guidance of the guide bar 30 and the drive bar 33.

[0058] It goes without saying that the displacement member 3 may have a cross-section of any shape, other than the circular one described. The [ Fig.5C ] thus illustrates another example in which the drive bar 33 and the guide bar 30 have a square cross-section. A rectangular or flattened cross-section could also be used.

[0059] According to an alternative embodiment, with reference to the [ Fig.6A ] and the [ Fig.6B ], only the angular guide portion 37 extends in the extension of the guide bar 30 and the angular drive portion 36 comprises a hollowed-out zone 38 in which the teeth 34 are mounted. Thus, the teeth 34 do not form a projection in the extension of the guide bar 30.

[0060] In this example, the guide bar 30 thus comprises an outer wall 32 of cylindrical cross-section and the drive bar 33 comprises an outer wall 35 which comprises a cylindrical cross-section of the same diameter except at the level of the angular drive portion 36 where the hollowed-out zone 38 has been hollowed out.

[0061] As illustrated in the [ Fig.6A ] and the [ Fig.6B ], the cross-section of the drive bar 33 is preferably included in that of the guide bar 30, so as to allow the use of a peripherally extending downstream guide member, such as that illustrated in the [ Fig.6A ]. In other words, the cross-section of the drive bar 33 is preferably of a shape and size less than or equal to the cross-section of the guide bar 30 so that a downstream guide member 25" adapted to peripherally guide the guide bar 30 can also be adapted to guide the drive bar 33.

[0062] So, in the example of the [ Fig.6A ] and the [ Fig.6B ], the teeth 34 extend radially inside the angular guide portion 37 relative to the axis of the displacement member 3. As illustrated in the [ Fig.6B ], it follows that the section of the drive bar 33, including the teeth 34, is included in the circular section of the guide bar 30 shown in dotted lines. Thus, the downstream guide member 25" ensures peripheral angular guidance of the guide bar 30 and partial guidance of the drive bar 33 by encircling the teeth 34.

[0063] The displacement member 3 can be guided and driven over its entire length without constraint. This advantageously makes it possible to reduce the length of the displacement member and, consequently, its size. Such integrated teeth 34 make it possible to limit the transverse size, which is advantageous for forming an air inlet 5 of low thickness.

[0064] There [ Fig.6C ] illustrates another example of a guide bar 30 comprising a hollowed-out area 38 in which the teeth 34 are mounted. In this example, the guide bar 30 has a rectangular section in which the hollowed-out area 38, also of rectangular section, has been hollowed out. Thus, the guide bar 30 has a U-shaped section. The guide bar 30 has two branches 40 connected to each other and delimiting the hollowed-out area 38 on either side. In this example, the two branches 40 extend horizontally, one above the other. The teeth 34 are mounted on the lower branch 40 and extend vertically. The two branches 40 are sufficiently distant from each other to allow the passage of the toothed wheel 24 to cooperate with the teeth 34.

[0065] THE figures 7A, 7B et 7C illustrate other embodiments of the invention in which the guide member(s) is / are in a form other than the ball bushing and the bearing of the figures 5A And 6A . In the example of the [ Fig.7A ], the upstream guide member 25' and the downstream guide member 25" are each in the form of rollers or rollers. More specifically, the upstream guide member 25' comprises an upper rotary member and a lower rotary member extending on either side of the guide bar 30 and cooperating with the latter so as to drive it in translation. The same applies to the downstream guide member 25" which is also configured to cooperate with the drive bar 33 as described previously.

[0066] In the example of the [ Fig.7B ], the guide member 25 is in the form of a fixed rail. The guide bar 30, and in this example the drive bar 33 also, are configured to cooperate directly or indirectly with the rail so as to allow their translation.

[0067] It goes without saying that the invention is not limited to the examples of guide members 25, 25', 25" described previously. Furthermore, in the example of the figures 5A , 6A And 7A , all the guide members 25', 25" are of identical nature but it goes without saying that one or more guide members 25', 25" could differ from the others. Thus, in the example of the [ Fig.7C ], the upstream guide member 25' is in the form of a ball bushing while the downstream guide member 25" is in the form of rollers.

[0068] According to another embodiment illustrated in the [ Fig.8 ], the displacement member 3 comprises several guide bars 30, namely two in this example, as well as a connecting element 39 connecting the guide bars 30 to the drive bar 33. In this example, the connecting element 39 extends substantially transversely to the longitudinal axis X and is in the form of a bar. As illustrated in the [ Fig.8 ], preferably, the drive bar 33 extends radially between the guide bars 30, in a centered manner to distribute the forces equally. Advantageously, such an embodiment makes it possible to reduce the number of displacement members 3 required and to limit the number of rack-and-pinion connections, which reduces the size and the on-board mass.

[0069] A method of using the air intake 5 previously described in flight is described below. The movable upstream part 1 is considered initially in the extended position P2 and the aircraft propulsion unit 8 generates a low subsonic speed in flight, namely a Mach number of less than 0.5.

[0070] With reference to the [ Fig.9 ], when the aircraft propulsion unit 8 accelerates to high subsonic speeds or to supersonic speeds, the toothed wheel 24 is set in motion to move the movable upstream part 1 in a first translation direction E1 oriented towards the retracted position P1, so as to reduce the section of the air inlet 5 and therefore the admitted interior air flow F-INT.

[0071] Still referring to the [ Fig.9], when the aircraft propulsion unit 8 decelerates to low subsonic speeds, the toothed wheel 24 is set in motion in a second direction of rotation, opposite to the first direction of rotation, to move the movable upstream part 1 in a second direction of translation E2 towards the outlet position P2, so as to increase the section of the air inlet 5 and therefore the admitted interior air flow F-INT.

[0072] Advantageously, the displacement members 3 of the air inlet 5 according to the invention make it possible to move the movable upstream part 1 in a reactive, rapid and precise manner thanks to a rack and pinion connection. In addition, the displacement members 3 are easily synchronizable and have a reduced mass and size compared to the linear cylinders traditionally used. This is particularly true in the embodiments with guidance of the drive bar 33, in which the guide member 25" makes it possible to successively guide the guide bar 30 and the drive bar 33. The size is particularly minimal and the guidance particularly precise in the embodiments where the teeth 34 are mounted in a hollowed-out zone 38 of the drive bar 33 so as to allow peripheral guidance of the guide bar 30.

Claims

1. An air inlet (5) for an aircraft propulsion assembly (8), said aircraft propulsion assembly (8) extending along a longitudinal axis (X) oriented from upstream to downstream and comprising a turbomachine (6) configured to allow propulsion of the aircraft from the acceleration of an internal air flow (F-INT) circulating from upstream to downstream in the turbomachine (6), said air inlet (5) circumferentially extending about the longitudinal axis (X) and comprising a movable upstream part (1), a fixed downstream part (2) and at least one moving member (3) configured to translationally move the movable upstream part (1) with respect to the fixed downstream part (2), said movable upstream part (1) comprising: - an upstream internal wall (10), pointing towards the longitudinal axis (X) and configured to guide the internal air flow (F-INT), - an upstream external wall (11), opposite to the upstream internal wall (10) and configured to guide an external air flow (F-EXT), and - an air inlet lip (12) connecting the upstream internal wall (10) and the upstream external wall (11), - said movable upstream part (1) being movable between a retracted position (P1), in which the movable upstream part (1) is adjacent to the fixed downstream part (2), and a deployed position (P2), in which the movable upstream part (1) is spaced apart upstream of the fixed downstream part (2) in order to delimit together a through channel (4) for fluidly circulating between the external air flow (F-EXT) and the internal air flow (F-INT), - which air inlet is characterized in that the moving member (3) comprises: - at least one guide bar (30) connected to the movable upstream part (1), and - a drive bar (33) comprising a plurality of teeth (34), - the fixed downstream part (2) comprising, for each moving member (3): - a toothed wheel (24) configured to be rotatably driven and to cooperate with the teeth (34) of the drive bar (33) so as to form a rack-and-pinion connection for moving the moving member (3) and the movable upstream part (1), and - at least one guide member (25, 25', 25") configured to guide the guide bar (30) when moving the moving member (3).

2. The air inlet (5) according to claim 1, wherein the movable upstream part (1) circumferentially extends about the longitudinal axis (X), and preferably forms a unitary assembly, more preferably a one-piece assembly.

3. The air inlet (5) according to any of claims 1 and 2, wherein: - the drive bar (33) extends as a downstream extension of the guide bar (30) and comprises an external wall (35) comprising an angular drive portion (36), where the teeth (34) are mounted, and an angular guide portion (37), - at least one guide member (25) in the form of a downstream guide member (25") configured to successively guide the guide bar (30) and the angular guide portion (37) of the drive bar (33).

4. The air inlet (5) according to claim 3, wherein the angular guide portion (37) extends over at least 120° from the external wall (35) of the drive bar (33), preferably over more than 180°, and more preferably 330° at the most.

5. The air inlet (5) according to any of claims 3 and 4, wherein the angular drive portion (36) comprises a recessed zone (38) in which the teeth (34) are mounted, preferably so as to extend radially inwardly of the angular guide portion (37) with respect to the axis (X3) of the moving member (3).

6. The air inlet (5) according to any of claims 3 to 5, wherein the downstream guide member (25") peripherally extends about the moving member (3).

7. The air inlet (5) according to any of claims 3 to 5, wherein the downstream guide member (25") partially peripherally extends about the moving member (3).

8. The air inlet (5) according to any of claims 1 and 2, wherein at least one moving member (3) comprises a plurality of guide bars (30) and a connection element (39) configured to connect the drive bar (33) to each guide bar (30).

9. An aircraft propulsion assembly (8) extending along a longitudinal axis (X) oriented from upstream to downstream and comprising a turbomachine (6) configured to allow propulsion of the aircraft from the acceleration of the internal air flow (F-INT) circulating from upstream to downstream in the turbomachine (6), said aircraft propulsion assembly (8) comprising an air inlet (5) according to one of claims 1 to 8, the turbomachine (6) preferably being supersonic.

10. A method for using in flight an air inlet (5) of an aircraft propulsion assembly (8) according to one of claims 1 to 8, wherein the toothed wheel (24) is driven in a first direction of rotation to move the movable upstream part (1) in a first direction of translation (E1) oriented from the deployed position (P2) to the retracted position (P1), so as to reduce the internal air flow (F-INT) taken in.