Mobile transmission device

Abstract

A device (22) for transmitting movement, the device comprising a screw (28) extending along an axis (X), a nut (26), a housing (24, 241), a first elastic member (104), a second elastic member (106), a first assembly (200), a second assembly (300), a first axial stopper (127), and a second axial stopper (123), wherein the first elastic member (104) is capable of being deformed independently of the second elastic member (106) under the action of a first axial force (E1), and the second elastic member (106) is capable of being deformed independently of the first elastic member (104) under the action of a second axial force exceeding a second threshold.

Description

[Technical field]

[0001] The present disclosure relates to a motion transmission device and a seat including said device. [Background technology]

[0002] In the field of passenger transport, and in particular air transport, it is known to equip aircraft with seats enabling passengers to be transported in a seated position, each seat comprising several elements, such as a backrest, a seat portion, a headrest, one or more armrests, etc.

[0003] To improve passenger comfort, each seat may be equipped with one or more drive systems that allow movement of the seat relative to the floor on which the seat is placed, or movement of various elements of the seat relative to others.

[0004] Generally, a drive system includes an actuator and a transmission chain. The mechanical parts that make up the drive system must be able to support crash-type loads, which occur, for example, during an emergency landing of an aircraft. The mechanical parts must also be able to support loads that arise when the seat movement suddenly stops or when a passenger suddenly falls onto the seat. All these loads are associated with large axial forces applied to the parts of the drive system, resulting in wear or even breakage.

[0005] Traditionally, the mechanical components of the drive system are over-engineered to limit the risk of wear and tear, however this over-engineering increases both the manufacturing costs of the drive system and the weight of the aircraft.

[0006] It is also known to provide brakes on the seat, which make it possible to stop the actuator in the case of loads with high axial forces, based on the phenomenon of friction between the brake's several parts. However, the brakes currently used are unidirectional brakes, meaning that they can only absorb loads applied in one direction. This means that the components of the drive system are not protected when the seat bounces during the application of loads with high axial forces. The two variants of unidirectional brakes must be implemented so that they are operable regardless of the direction in which they are intended to be installed on the seat. This therefore increases the costs of designing and manufacturing the brake. Summary of the Invention [Problem to be solved by the invention]

[0007] This disclosure improves the situation. [Means for solving the problem]

[0008] For this purpose, a transmission device for transmitting the movement is proposed, the device comprising: A screw extending along an axis; a nut cooperating with the screw; Housing and A first elastic member; A second elastic member; a first assembly comprising the nut; a second assembly comprising the housing; and a first axial stopper axially integral with the first assembly and capable of cooperating with a first complementary axial stopper of the second assembly, a first axial clearance being formed between the first axial stopper and the first complementary axial stopper; a second axial stopper axially integral with the first assembly and capable of cooperating with a second complementary axial stopper of the second assembly, a second axial clearance being formed between the second axial stopper and the second complementary axial stopper; Equipped with the first resilient member is oriented in a first direction and is capable of being deformed independently of the second resilient member under the influence of a first axial force applied to the first resilient member by the first assembly, thereby reducing a first axial clearance such that when said first axial force exceeds a first threshold, the first axial stop abuts a first complementary axial stop; The second resilient member is oriented in a second direction opposite to the first direction and is capable of being deformed independently of the first resilient member under the influence of a second axial force applied to the second resilient member by the first assembly, thereby reducing the second axial clearance and causing the second axial stop to abut against a second complementary axial stop when the second axial force exceeds a second threshold.

[0009] In this specification, the terms "axial", "radial" and "circumferential" are defined with respect to the axis of extension of the thread. In particular, "axial" means along or parallel to the axis of extension of the thread, and radial means along any axis transverse or substantially transverse to that axis. "Circumferential" is understood to mean around the aforementioned axis.

[0010] In the proposed device, the deformation of the first or second elastic member abutting the first assembly against the second assembly causes the axial force to be dissipated through the second assembly, and in particular the housing, rather than through other parts of the device which are more susceptible to wear and tear. Thus, the risk of wear and tear on the device is reduced without the need to over-design parts of said device.

[0011] Furthermore, due to the presence of a first elastic member and a second elastic member, which can be deformed independently of each other under the effect of axial forces directed in opposite directions, it is possible for the transmission device to constitute a bidirectional brake capable of absorbing the axial forces received independently of the direction in which the seat of the transmission device is installed, even in the event of the seat bouncing.

[0012] The first resilient member and the second resilient member may be resilient washers.

[0013] The first and second thresholds correspond, for example, to the maximum axial forces that can be applied to the first and second elastic members, respectively, without deforming them. Preferably, the first and second thresholds are between 3000N and 6000N, more preferably between 3325N and 5556N. For example, the first and second thresholds are equal to 4440N. Any axial force applied by the first assembly to the first elastic member, directed in a first direction, that exceeds the first threshold, can be associated with a crash-type load or a large axial force applied to the device in the first direction. Similarly, any axial force applied by the first assembly to the second elastic member, directed in a second direction, that exceeds the second threshold, can be associated with a crash-type load or a large axial force applied to the device in the second direction.

[0014] The screw, housing and nut may be coaxial.

[0015] The housing and the nut may include a bore, such that the screw may be partially contained within the housing and the nut.

[0016] The first assembly may be configured to rotate about the extension axis of the screw when the proposed device transmits movement. When a crash-type load or a large axial force load is applied to the device, the first assembly may also move axially in the direction of the load application. This axial movement of the first assembly creates an axial force in a first direction or a second direction that the first assembly exerts on the first elastic member or the second elastic member.

[0017] The second assembly may be configured to be immobile when the proposed device transmits movement, as well as during application of crash-type loads or large axial force loads.

[0018] When the first assembly comes into contact with the second assembly, the axial movement of the first assembly may be blocked. Moreover, friction may occur between the first stopper and the first complementary stopper, or between the second stopper and the second complementary stopper. This friction may slow down the rotational movement of the first assembly.

[0019] The screw and the nut form a screw-nut system that is preferably reversible, where "reversible" is understood to mean that rotation of the nut about the extension axis of the screw causes axial translation of the screw.

[0020] The nut and the screw may include complementary tappings and threads, respectively, shaped such that rotation of the nut about the axis of the screw causes axial translation of the screw. The tappings of the nut and the threads of the screw may engage one another directly or indirectly.

[0021] In some cases, the rotation of the nut is prevented with a sufficient torque so that the transmission device operates when the axial force applied to the device is greater than a first or second threshold. For this purpose, the nut may be connected to an element that allows it to be braked. For example, the nut may be connected to a friction brake or a motor with a high detent torque.

[0022] The apparatus may further comprise a first preload element and a second preload element, the first preload element capable of adjusting a preload stress acting on the first elastic member independent of a preload stress acting on the second elastic member, and the second preload element capable of adjusting a preload stress acting on the second elastic member independent of a preload stress acting on the first elastic member.

[0023] The first preload element and the second preload element therefore allow for independent adjustment of the preload stresses acting on the first elastic member and the second elastic member, respectively. Thus, the preload stresses acting on the first and second elastic members may be different such that they do not cancel each other out. Thus, the transmission device constitutes an operable bidirectional brake.

[0024] The first preload element and the second preload element may be installed in the bore of the housing. For example, the first preload element and the second preload element may each have a radial outer periphery connected to the second assembly and a free radial inner periphery disposed facing the first assembly. Thus, a radial clearance may be formed between the first assembly and the first and second preload elements. This prevents the first and second preload elements from moving with the first assembly rotating about the extension axis of the screw.

[0025] To connect the first and second preload elements to the housing, the radial periphery of each of the preload elements may include a thread complementary to a respective tapping disposed on the housing. This configuration also allows the first and second preload elements to be moved axially to adjust the preload stress acting on each elastic member. For example, the first preload element may be moved axially closer to the first elastic member by threading its thread into the respective tapping of the housing to increase the preload stress of the first elastic member. Similarly, the first element may be moved axially further away from the first elastic member by loosening its thread in the respective tapping of the housing to reduce the preload stress of the first elastic member. The same principle may be applied to the second preload element to increase or decrease the preload stress of the second elastic member.

[0026] It should be noted that the axial movements of the first and second preload elements are independent of one another, thereby allowing different preload stresses to be applied to each resilient member.

[0027] It is clear that the terms "external" or "outer" and "internal" or "inner" in this specification are understood to mean radially.

[0028] The apparatus may comprise at least one bearing comprising a radially inner ring arranged facing the first assembly and a radially outer ring arranged facing the second assembly, the radial outer periphery of each elastic member being in axial direct or indirect abutment against the radially outer ring of said bearing and the radially inner periphery being in axial abutment against the preload element.

[0029] The first resilient member axially abuts against the radially outer ring of the at least one bearing on a side of the at least one bearing axially opposite to the side of the at least one bearing, and the second resilient member axially abuts against said radially outer ring.

[0030] The axial force applied by the first assembly to each of the elastic members may pass through at least one bearing. In particular, the axial force may be transmitted from the first assembly to a radially inner ring of at least one bearing, which causes an axial movement of the radially outer ring in the direction of the axial force. Each elastic member abuts directly or indirectly in the axial direction against the radially outer ring of said bearing, so that the axial movement of the radially outer ring causes a deformation of the elastic member to which the axial force is applied.

[0031] The second assembly may include a shoulder extending radially from the radially inner wall of the housing. The first resilient member may then be disposed on a first side of the shoulder of the second assembly and the second resilient member may be disposed on a second side of the shoulder of the second assembly opposite the first side.

[0032] The first and second resilient members are disposed on opposite sides of the shoulder of the second assembly to provide a differential force path for axial forces applied in a first direction and axial forces applied in a second direction.

[0033] The shoulder of the second assembly may be annular.

[0034] The first bearing may be disposed between the first elastic member and a first side of the shoulder of the second assembly. The second bearing may be disposed between the second elastic member and a second side of the shoulder of the second assembly. The radial periphery of the first elastic member then comes into axial abutment against the radial outer ring of the first bearing, and the radial periphery of the second elastic member comes into axial abutment against the radial outer ring of the second bearing. Thus, each elastic member comes into abutment against the outer ring of a different bearing, which increases the independence between the forces experienced by each of the elastic members.

[0035] The first assembly may include a shoulder extending radially from a radially outer wall of the first assembly, the shoulder of the first assembly being disposed radially facing the shoulder of the second assembly.

[0036] The shoulder of the first assembly allows for better separation of force paths for axial forces applied in a first direction and axial forces applied in a second direction.

[0037] The shoulder of the first assembly may have an axial length that is shorter than said axial length of the shoulder of the second assembly, and thus the preload of the first and second resilient members is independently adjustable on two sides of the shoulders of the first and second assemblies.

[0038] The bearing may be disposed radially inward of the shoulder of the second assembly.

[0039] The bearing may have an axial length substantially equal to the axial length of the shoulder of the second assembly. The bearing may be a double row bearing, which can absorb more axial loads. Thus, safety may be improved in case of crash type loads or any loads with large axial forces.

[0040] The bearing may be held in place on the shoulder of the second assembly by means of a second annular spacer and the first annular spacer projecting radially from the first assembly and positioned axially, one on either side of the radially inner ring of the bearing.

[0041] The apparatus may further comprise a first annular support plate arranged between the radially outer ring of the bearing and the radial outer periphery of the first resilient member, and a second annular support plate arranged between the radially outer ring of the bearing and the radial outer periphery of the second resilient member, wherein the radial outer periphery of the first resilient member abuts the first support plate and the radial outer periphery of the second resilient member abuts the second support plate.

[0042] The first plate and the second plate may be annular. The axial half cross sections of the first and second plates preferably have an inverted L-shape.

[0043] The first and second support plates may be free to move relative to the first and second assemblies. In this case, the first and second support plates may be axially wedged between the radially outer ring of the bearing and the radial outer circumference of the first and second elastic members, respectively. They may thus be held in place while being able to move together with the radially outer ring of the bearing, thereby allowing the first or second elastic members to deform when the axial force applied by the first assembly is greater than a first or second threshold.

[0044] The first support plate may be radially facing the first spacer, and the second support plate may be radially facing the second spacer.

[0045] According to another aspect, a seat for an aircraft is proposed, comprising a fixed part intended to be fixed to a fixed part of the aircraft and a movable part capable of being moved relative to the fixed part, a transmission device for transmitting a movement as mentioned above is mounted between the movable part and the fixed part, a nut of the transmission device for transmitting a movement can be rotated by an actuator, a screw is connected to said movable part of the seat and a housing is connected to said fixed part of the seat.

[0046] The transmission device for transmitting a movement transmits to the movable part of the seat a movement that causes the movable part to move relative to the fixed part of said seat, in particular, a screw of the transmission device is connected to the movable part of the seat, so that the movement of this movable part is integral with the axial movement of the screw.

[0047] The fixed part of the seat may be directly or indirectly connected to a fixed part of the aircraft, which may for example correspond to the floor.

[0048] In some cases, the fixed and movable portions of the seat each correspond to one of the elements of the seat. In one non-limiting example, the movable portion corresponds to the backrest, while the fixed portion of the seat corresponds to the portion of the seat that is connected to the aircraft floor directly or by legs.

[0049] It should be noted that it is not excluded that an element of a seat constituting its fixed part in one given situation constitutes a movable part of the seat in another situation. For example, a seat connected to the floor by legs can move relative to the legs, the legs being included in the fixed part of the seat and the seat part being part of the movable part of the seat. Similarly, an element of a seat constituting its movable part in a given situation may constitute a fixed part of the seat in another situation.

[0050] According to another non-limiting example, the fixed part of the seat comprises, for example, a slide fixed to the floor of the aircraft, and the movable part of the seat comprises, for example, several legs connected to the slide so that they can slide along the slide.

[0051] Other features, details and advantages will become apparent upon reading the following detailed description and examining the accompanying drawings. [Brief description of the drawings]

[0052] [Figure 1] 1 is a schematic side view of an aircraft seat with a transmission device for transmitting movement according to the present invention; [Diagram 2] FIG. 2 is a schematic diagram of an axial cross section of a transmission device for transmitting movement of the seat of FIG. 1 in accordance with one embodiment of the present invention, and shows the force path followed by the transmission device when an axial force is applied to the transmission device in a first direction. [Diagram 3] 3 shows the transmission device for transmitting movement of FIG. 2 and the same representation of the force path followed by the transmission device when an axial force in a second direction opposite to the first direction is applied to the transmission device. [Figure 4] FIG. 2 is a schematic diagram of an axial cross section of a transmission device for transmitting movement generated by the seat actuator of FIG. 1 according to another embodiment of the present invention, and a diagram showing the force path followed by the transmission device when an axial force is applied to the transmission device in a first direction. [Diagram 5] 5 shows the transmission device for transmitting movement of FIG. 4 and the same representation of the force path followed by the transmission device when an axial force in a second direction opposite to the first direction is applied to the transmission device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] 1 shows in particular a seat 2 for an aircraft. The seat 2 comprises a seat portion 4, a backrest 6 and a headrest 8. The seat 2 may also comprise a footrest 10.

[0054] The seat 2 is intended to be connected to a fixed part of the aircraft, in particular to the floor. For this purpose, the seat 2 comprises legs 12 and slides 14. The slides 14 comprise, for example, two rails fixed to the ground, each leg 12 being attached to one of the rails so as to be able to slide along the respective rail. The seat 2 can thus be moved forwards or backwards.

[0055] The seat 2 includes an electric drive system 18. The system 18 may be dedicated to moving one of the elements of the seat 2 (seat portion 4, backrest 6, headrest 8, footrest 10, etc.) relative to the other elements. Alternatively, the system 18 is dedicated to the seat 2 moving on the slide 14.

[0056] In the following, the element of the seat 2 that is moved is called the "movable part" and the element that moves relative to it is called the "fixed part".

[0057] The drive system 18 comprises, for example, an actuator 20 capable of generating a movement, in particular a rotation, and a transmission 22 for transmitting the movement. In particular, the transmission is configured to convert the movement generated by the actuator into a movement adapted to move a movable part relative to a fixed part of the seat.

[0058] The drive system 18 further comprises mechanical parts (not shown), such as gears or connecting rods, adapted to transmit the movement generated by the actuator 20 to the transmission 22. More precisely, these mechanical parts connect the actuator 20 to the transmission 22. Such mechanical parts preferably form part of a reducer, for example a multi-stage reducer. The reducer makes it possible to reduce the speed of the movement generated by the actuator 20 before it is transmitted to the transmission 22. The reduction in the speed of the movement generated by the actuator 20 leads to an increase in the torque output by the actuator 20.

[0059] Next, the transmission device 22 will be described with reference to FIGS.

[0060] In a first embodiment, shown in FIGS. 2 and 3, the device 22 comprises a housing 24, a nut 26, and a screw 28 extending along an axis X.

[0061] The housing 24 has a generally cylindrical shape extending axially between a first end 30 and a second end 32. The housing 24 includes a radially outer wall 34 and a radially inner wall 36. The radially inner wall 36 defines a bore 38 that extends axially through the housing 24 between the first end 30 and the second end 32. The bore 38 preferably has a generally circular transverse cross-section along its entire length. As used herein, "transverse" means disposed in a plane generally perpendicular to the X-axis.

[0062] The housing 24 includes a preferably annular shoulder 40 extending radially from the radially inner wall 36. In particular, the shoulder 40 includes first and second surfaces 42, 44 that are generally parallel and project radially into the bore 38. The shoulder 40 further includes a connecting surface 46 that extends axially within the bore 38. The connecting surface 46 connects the first and second surfaces 42, 44 of the shoulder 40.

[0063] The axial distance between the first and second faces 42 , 44 defines the width of the shoulder 40 .

[0064] Advantageously, the radially inner wall 36 of the housing 24 is provided with a first tapping 47 and a second tapping 48. The first tapping 47 is arranged between the first end 30 of the housing 24 and the first surface 42 of the shoulder 40. The second tapping 48 is arranged between the second end 32 of the housing 24 and the second surface 44 of the shoulder 40. Advantageously, but not exclusively, the tappings 47, 48 are identical.

[0065] As described in more detail below, the first tapping 47 enables a first preload element 108 to be connected to the housing 24, and the second tapping 48 enables a second preload element 110 to be connected to the housing 24.

[0066] Radially inner wall 36 may further include first and second axial stops, which are not shown in Figures 2 and 3. The first and second axial stops of wall 36 prevent axial movement of first preload element 108 and second preload element 110, respectively, as described below.

[0067] Also, as will be explained in detail, the housing 24 is configured to be immobile in the device 22. Advantageously, when the device 22 is installed in the seat 2, the housing 24 is connected to a fixed part of the seat 2.

[0068] The nut 26 has a generally cylindrical shape extending axially between a first end 50 and a second end 52. The nut 26 includes a radially outer wall 54 and a radially inner wall 56.

[0069] The radially outer wall 54 includes a radially outwardly projecting annular flange 60. One face 62 of the flange 60 is axially aligned with the first end 50 of the nut 26. Advantageously, the diameter of the flange 60 is greater than the diameter of the bore 38 of the housing 24.

[0070] The radially inner wall 56 defines a bore 58 that extends axially through the nut 26 between the first and second ends 50, 52. Preferably, the bore 58 is generally circular in cross section along its entire length.

[0071] The radially inner wall 56 is preferably provided with an annular shoulder 64. The shoulder 64 has a surface 66 that extends radially within the bore 58. A vector normal to the surface 66 is directed toward the first end 50 of the nut 26.

[0072] The shoulder 64 divides the radially inner wall 56 into a first region 68 and a second region 70. The first region 68 extends between the shoulder 64 and the first end 50 of the nut 26. The second region 70 extends between the shoulder 64 and the second end 52 of the nut 26. As can be seen from Figures 2 and 3, the diameter of the bore 58 along the first region 68 is larger than the diameter of the bore 58 along the second region 70, but is smaller than the diameter of the housing bore 38.

[0073] The first region 68 of the radially inner wall 56 includes a tapping 72. The tapping 72 allows for connection of the nut 26 to a sleeve 80, which will be described below. Advantageously, the tapping 72 is designed to move together when the nut 26 and the sleeve 80 are connected, as will be described in more detail below.

[0074] The second region 70 of the radially inner wall 56 includes a tapping 74 intended to engage, directly or indirectly, the thread 28. In Figs. 2 and 3, the tapping 74 engages the thread 28 via a number of balls 76, but it could engage the thread 28 via a number of rollers, among other possibilities. Alternatively, the tapping 74 may be trapezoidal and directly engaged with the thread 28. The tapping 74 is designed to cause axial movement of the thread 28 when the nut 26 rotates about the X-axis.

[0075] Advantageously, the nut 26 is connected to a reducer of the drive system 18. The rotational movement generated by the actuator 20 is thus transmitted to the nut 26 with a reduced speed and an increased torque, so that the nut 26 rotates about the X-axis.

[0076] As can be seen in FIGS. 2 and 3, the screw 28 is partially received in the bore 38 of the housing and in the bore 58 of the nut 26 .

[0077] The radially outer surface of the screw 28 includes threads 78 shaped to directly or indirectly engage with the tappings 74 of the nut 26 as described above. Thus, the screw 28 may be a ball screw, a roller screw, or a trapezoidal screw, among other possibilities, such that the screw 28 and the nut 26 cooperate such that rotation of the nut 26 about the X-axis causes axial movement of the screw 28.

[0078] When the device 22 is installed on the seat 2, the screw 28 is preferably directly or indirectly connected to the movable part of the seat 2. Thus, the movable part is moved relative to the fixed part of the seat 2 together with the screw 28. When the movable part corresponds to the leg 12 and the fixed part of the seat 2 corresponds to the slide 12, the device 22 is able to move the seat 2 back and forth.

[0079] As described above, device 22 further includes sleeve 80. Sleeve 80 has a substantially cylindrical shape extending axially between first end 82 and second end 84. Sleeve 80 includes a radially outer wall 85 and a radially inner wall 86.

[0080] A radially outer wall 85 of the sleeve 80 includes a first thread 87 and a second thread 88 .

[0081] A first thread 87 extends axially on a first end 89 of the sleeve 80 with the first end 82. The first thread 87 is complementary to the tappings 72 of the nut 26 and allows for connection of the nut 26 to the sleeve 80.

[0082] A second thread 88 extends axially on a second end 90 of the sleeve 80 with the second end 84. The second thread 88 makes it possible to connect the sleeve 80 to a closure nut 96, which will be described below.

[0083] The radially outer wall 85 further includes a preferably annular shoulder 92 extending radially from the radially outer wall 85. In particular, the shoulder 92 includes a first surface 93 and a second surface 94 that are generally parallel and project radially outwardly from the sleeve 80. The shoulder 92 further includes a connecting surface 95 that extends axially and connects the first and second surfaces 93, 94 of the shoulder 92.

[0084] The axial distance between the first and second faces 93, 94 defines a width of the shoulder 92. Preferably, the width of the shoulder 92 is less than the width of the shoulder 40 of the housing 24.

[0085] The radially inner wall 86 defines a bore 107 that traverses the sleeve 80 between the first and second ends 82, 84. Advantageously, the bore 107 has a generally circular cross-section. As can be seen in Figures 2 and 3, the diameter of the bore 107 is preferably approximately equal to the diameter of the bore 58 of the nut 26 along the second region 70 of the radially inner wall 56. This allows the bores 58 and 107 to be in extension of one another when the nut 26 and sleeve 80 are connected.

[0086] The closure nut 96 has a generally annular shape with a central bore 97. The diameter of the central bore 97 is preferably equal to or greater than the diameter of the bore 107 of the sleeve 80. The closure nut 97 is provided with a closure face 101 oriented axially towards the nut 26. Advantageously, the radially outer diameter of the closure face 101 is greater than the diameter of the bore 38 of the housing 24.

[0087] The radially inner edge of the closure nut 96 is provided with a tapping 98. The tapping 98 is complementary to the second thread 88 of the sleeve 80 and allows the closure nut 96 to be connected to the sleeve 80. The tapping 98 and the thread 88 are designed so that the sleeve 80 and the closure nut 96 move together as one unit when they are connected. Since the sleeve 80 moves together with the nut 26, the closure nut 96 also moves together with the nut 26.

[0088] As can be seen from Figures 2 and 3, the sleeve 80 is shaped to extend axially inside the bore 38 of the housing 24. In particular, the sleeve 80 is disposed radially between the threads 28 and the radially inner wall 36 of the housing 24. In this position, the housing 24 and the sleeve 80 are coaxial. Advantageously, the sleeve shoulder 92 and the housing shoulder 40 are disposed radially opposite one another when the sleeve 80 is installed inside the housing bore 38.

[0089] A circumferential cavity 99 is formed between the radially outer wall of sleeve 80 and the radially inner wall of housing 24. Cavity 99 has a substantially constant thickness such that it narrows in the area where shoulders 40, 92 radially oppose one another.

[0090] The transmission device 22 further comprises a first bearing 100, a second bearing 102, a first resilient member 104, a second resilient member 106, and first and second preload elements 108, 110. The bearings 100, 102, the resilient members 104, 106, and the preload elements 108, 110 are disposed within the cavity 99.

[0091] The first and second bearings 100, 102 include a radially inner ring 112 and a radially outer ring 114. A plurality of rolling elements 117 are arranged in the circumferential direction between the rings 112 and 114. In Figures 2 and 3, the bearings 100, 102 include a row of rolling elements 117 in the circumferential direction.

[0092] The radially inner ring 112 is arranged to radially face the sleeve 80, while the radially outer ring 114 is arranged to radially face the housing 24. More precisely, the radially inner ring 112 is in contact with the radially outer wall 85 of the sleeve 80 and the radially outer ring 114 is in contact with the radially inner wall 36 of the housing 24.

[0093] A radially inner ring 112 of each bearing 100, 102 is disposed axially facing one of the faces 93, 94 of the shoulder 92 of the sleeve 80. A radially outer ring 114 of each bearing 100, 102 is disposed axially facing one of the faces 42, 44 of the shoulder 40 of the housing 24.

[0094] As can be seen in Figures 2 and 3, the first and second bearings 100, 102 are each disposed on opposite sides of the shoulder 40 of the housing 24 and the shoulder 92 of the sleeve 80. Advantageously, the radially outer ring 114 of the bearings 100, 102 contacts one of the faces 42, 44 of the shoulder 40. In Figures 2 and 3, the radially outer ring 114 of the first bearing 100 contacts face 42, while the radially outer ring 114 of the second bearing 102 contacts face 44.

[0095] The radially inner ring 112 is configured to rotate with the sleeve 80 about the X-axis. The radially outer ring 114 is configured to be fixed. Thus, the first and second bearings 100, 102 enable a durable assembly of the sleeve 80, which is rotatably moveable about the X-axis, with the fixed housing 24.

[0096] The first and second bearings 100, 102 are, for example, angular contact bearings.

[0097] First preload element 108 and second preload element 110 have a generally annular shape with an inner radial periphery 115 and an outer radial periphery 116 .

[0098] A radially inner periphery 115 of each preload element 108 , 110 is disposed against the radially outer wall 85 of the sleeve 80 such that a radial clearance 118 exists between each preload element 108 and the sleeve 80 .

[0099] The radial periphery 116 of each preload element 108, 110 is arranged facing the radially inner wall 36 of the housing 24. In particular, as mentioned above, the first preload element 108 is connected to the first tapping 47, while the second preload element 110 is connected to the second tapping 48. To this end, the radial periphery 116 of each preload element is provided with a thread 119, 120 complementary to the tappings 47, 48, respectively. As the preload elements 108, 110 are threaded into the housing 24, they can be moved axially towards or away from the respective elastic members 104, 106 in order to adjust the preload stress of each of these elastic members 104, 106.

[0100] To prevent axial movement of the preload elements 108, 110 towards the resilient members 104, 105, respectively, each preload element 108, 110 may be provided with an axial stop (not shown) complementary to an axial stop that the wall 36 of the housing may be provided with.

[0101] A first resilient member 104 is disposed in the cavity 99 between the first bearing 100 and the first preload element 108. A second resilient member 106 is disposed in the cavity 99 between the second bearing 102 and the second preload element 110.

[0102] The first and second resilient members 104, 106 are, for example, resilient washers. Each of the washers 104, 106 includes a radially inner periphery 121 arranged to face the radially outer wall 85 of the sleeve 80 and a radially outer periphery 122 arranged to face the radially inner wall 36 of the housing 24.

[0103] Advantageously, the washers 104, 106 have a generally frusto-conical shape. As can be seen in Figures 2 and 3, the radially inner periphery 121 of the washers 104, 106 abuts the first preload element 108 and the second preload element 110, respectively. This allows the preload stress of each of the washers 104, 106 to be adjusted by axial movement of the respective preload elements 108, 110.

[0104] The radial periphery 122 of the washers 104, 106 come into contact with the outer rings of the first bearing 100 and the second bearing 102, respectively.

[0105] The preload stress of the first washer 104 prevents the washer 104 from deforming when the device 22 is subjected to an axial force below a first threshold. When the axial force to which the device 22 is subjected is greater than the first threshold, the washer 104 is in axial compression. Similarly, the preload stress of the second washer 106 prevents the washer 106 from deforming when the device 22 is subjected to an axial force below a second threshold. When the axial force to which the device 22 is subjected is greater than the second threshold, the washer 106 is in axial compression.

[0106] Kinematically, the device 22 comprises a first assembly 200 and a second assembly 300. The first assembly 200 comprises the components of the device 22 that are rotationally movable about the X-axis. Thus, in the case of the device 22 of Figures 2 and 3, the first assembly 200 comprises the nut 26, the sleeve 80 and the closure nut 96. The second assembly 300 comprises the components of the device that are fixed. In the case of the device 22 of Figures 2 and 3, the second assembly 300 comprises the housing 24, the preload elements 108, 110 and the elastic members 104, 106.

[0107] The first and second assemblies 200, 300 are advantageously coaxial.

[0108] As mentioned above, the diameter of the flange 60 of the nut 26 is larger than the diameter of the bore 38 of the housing 24, allowing the flange 60 and the end 30 of the housing 24 to be partially opposed to each other in the axial direction. In this way, a first axial clearance 201 is formed between a portion 123 of the face 62 of the flange 60 and a portion 125 of the first end 30 of the housing 24. As will be explained below, the portion 123 of the face 62 constitutes an axial stop 123, while the portion 125 of the end 30 of the housing 24 constitutes a complementary axial stop 125. Preferably, the axial length of the first clearance is equal to or less than the value of the axial compression experienced by the second elastic member 106 when the axial force experienced by the device 22 is greater than a second threshold value.

[0109] As mentioned above, the diameter of the closure surface 101 is larger than the diameter of the bore 38 of the housing 24, allowing the closure surface 101 and the end 32 of the housing 24 to be partially opposed to each other in the axial direction. A second axial clearance 301 is thus formed between a portion 127 of the closure surface 101 of the closure nut 96 and a portion 129 of the second end 32 of the housing 24. As will be explained below, the portion 127 of the closure surface 101 constitutes an axial stop 127, while the portion 129 of the end 32 of the housing 24 constitutes a complementary axial stop 129. Preferably, the axial length of the second clearance is less than or equal to the value of the axial compression experienced by the first elastic member 104 when the axial force experienced by the device 22 is greater than a first threshold value.

[0110] The operation of the device 22 according to the embodiment of Figures 2 and 3 will now be described.

[0111] Under normal operating conditions, meaning that the device 22 is not subjected to an axial force greater than the first or second thresholds, the first assembly 200 is rotatably movable about the X-axis relative to the second assembly 300. In particular, the actuator 20 rotates the first assembly 200 about the X-axis while the second assembly 300 remains stationary. The rotation of the first assembly 200 translates the screw 28 in the X-direction, as explained above. This causes the movable part of the sheet to move relative to its fixed part.

[0112] Advantageously, under normal operating conditions, there is no axial movement of the first assembly 200 relative to the second assembly 300. Thus, the length of the axial clearances 201, 301 is unchanged.

[0113] As shown diagrammatically in FIG. 2 by a dotted curve, when an axial force E1 exceeding a first threshold is applied to the screw 28 in a direction directed towards the nut 26, the force E1 is transmitted from the screw 28 to the nut 26 and the sleeve 80. This causes a movement of the first assembly 200 in the direction of the force E1. The movement of the first assembly 200 causes an integral movement of the shoulder 92, which causes a transmission of the axial force E1 to the inner ring 112 of the first bearing 100, which in turn causes a movement of the outer ring 114 of the bearing 100 in the direction of the force E1. The outer ring 114 then causes a deformation of the first elastic member 104, in particular an axial compression. The force E1 is then transmitted to the first preload element 108 and is finally dissipated through the housing 24.

[0114] As mentioned above, the length of the clearance 301 is equal to or less than the value of the axial compression experienced by the elastic member 104 in the presence of an axial force having the characteristic of the force E1. The compression of the elastic member 104 thus reduces the length of the clearance 301 until the axial stop 127 of the first assembly 200 comes to abut the complementary axial stop 129 of the second assembly 300. This, on the one hand, blocks the axial movement of the first assembly 200 relative to the second assembly 300. On the other hand, due to the friction existing between the axial stop 127 and the complementary axial stop 129, the rotation of the first assembly 200 about the X-axis is braked.

[0115] The dotted curve in FIG. 3 shows diagrammatically the force path of the device 22 when an axial force E2 exceeding a second threshold is applied to the screw 28 in a direction directed towards the closure nut 96. In this case, the force E2 is transmitted from the screw 28 to the nut 26 and the sleeve 80. This causes a movement of the first assembly 200 in the direction of the force E2. The movement of the first assembly 200 causes an integral movement of the shoulder 92, which transmits the axial force E2 to the inner ring 112 of the second bearing 102, which in turn causes a movement of the outer ring 114 of the bearing 102 in the direction of the force E2. The outer ring 114 then causes a deformation of the second elastic member 106, in particular an axial compression. The force E2 is then transmitted to the second preload element 110 and is finally dissipated through the housing 24.

[0116] As mentioned above, the length of the clearance 201 is equal to or less than the value of the axial compression experienced by the elastic member 106 in the presence of an axial force having the characteristic of the force E2. The compression of the elastic member 104 thus causes a reduction in the length of the clearance 201 until the axial stop 123 of the first assembly 200 comes to abut the complementary axial stop 125 of the second assembly 300. This, on the one hand, prevents the axial movement of the first assembly 200 relative to the second assembly 300. On the other hand, the rotation of the first assembly 200 about the X-axis is braked due to the friction existing between the axial stop 123 and the complementary axial stop 125.

[0117] Figures 4 and 5 show a second embodiment of the device 22. In the following, unless otherwise indicated, components bearing the same references as in Figures 2 and 3 are similar or identical to those described above and will not be described again.

[0118] In this embodiment, the device 22 comprises a housing 241 , a nut 261 and a screw 281 .

[0119] The housing 241 and the screw 281 are similar to the housing 24 and the screw 28 described above with reference to Figures 2 and 3, respectively. As a result, they will not be described again. However, it should be noted that in Figures 4 and 5, first and second stops for preventing axial movement of the preload elements 108, 110 are shown. The first stop is designated 243, while the second stop is designated 245. In these figures, the complementary stops provided on the preload elements 108, 110 are also visible. The complementary stop for the stop 243 is designated 247, and the complementary stop for the stop 245 is designated 249.

[0120] The nut 261 differs from the nut 26 in that the radially outer wall 54 does not comprise the annular flange 60. A thread 272 is provided on the radially outer wall 54. The thread 272 is, for example, annular. The thread 272 is provided on the end 255 of the radially outer wall 54 that comprises the first end 50.

[0121] As can be seen from FIGS. 4 and 5, in the nut 261 the first region 68 of the radially inner wall 56 does not include tappings 72 .

[0122] The device 22 further comprises a sleeve 801 integrated in the closure nut 961 .

[0123] The closure nut 961 is similar to the closure nut 96 of Figures 2 and 3. However, in the closure nut 961, the closure surface 101 has a diameter smaller than the diameter of the bore 38 through the housing 241. Thus, the closure nut 961 may be disposed inside the housing 241.

[0124] The sleeve 801 comprises a cylindrical envelope 802 and a crown 803 .

[0125] Cylindrical envelope 802 extends between a first end 804 and a second end 805 and includes a radially outer wall 806 and a radially inner wall 807. Radially inner wall 807 defines a bore 808 that axially traverses cylindrical envelope 802 between first end 804 and second end 805. Bore 808 is similar to bore 107 of sleeve 80 of device 22 of Figures 2 and 3 and will not be described again here.

[0126] The radially outer wall 806 of the cylindrical envelope 802 is provided with a radial protrusion 809 at an end 810 that comprises the first end 804 .

[0127] The radially outer wall 806 of the cylindrical envelope 802 is provided at the end 811 which comprises the second end 805 with the thread 88 described above with reference to Figures 2 and 3. The thread 88 is complementary to the tapping 98 of the closure nut 961.

[0128] The crown 803 comprises a radial portion 812 and an axial portion 813. The radial portion 812 extends radially outward from the sleeve 801 between the first end 804 of the cylindrical envelope 802 and the axial portion 813. Thus, the diameter of the radial portion 812 is greater than the diameter of the bore 808.

[0129] The axial portion 813 extends axially between an end integral with the radial portion 812 and a free end.

[0130] An axially inner wall 814 of the radial portion 812 and an axially inner wall 815 of the axial portion 813 define a receiving portion for assembly with the nut 261. In particular, the radially inner wall 815 of the axial portion 813 includes tappings 816 that are complementary to the threads 272 on the radially outer wall 54 of the nut 261.

[0131] In the embodiment of Figures 4 and 5, a single bearing 900 is provided in the device 22. The bearing 900 comprises a radially inner ring 112 and a radially outer ring 114, such as those described in detail with reference to Figures 2 and 3. Preferably, the bearing 900 is a double row bearing.

[0132] The bearing 900 is disposed on the shoulder 40 of the housing 241 .

[0133] The first annular spacer 901 and the second annular spacer 902 are connected to the cylindrical envelope 802. In particular, the spacers 901, 902 protrude radially from the cylindrical envelope 802.

[0134] The first spacer 901 contacts a radial projection 809 from the cylindrical envelope 802. The second spacer 902 contacts a closure nut 907.

[0135] Advantageously, the spacers 901, 902 are arranged axially, one on either side of the radially inner ring 112 of the bearing 900. This makes it possible to hold the bearing 900 in place.

[0136] Spacers 901 and 902 are connected to the cylindrical envelope and therefore move together with sleeve 801 .

[0137] The first support plate 904 and the second support plate 905 are arranged one on either side of the shoulder 42 of the housing 241. The support plates 904, 905 are therefore arranged one on either side of the bearing 900. Advantageously, the support plate 904 is radially opposed to the spacer 901 when no axial force above the above-mentioned first threshold is acting on the device 22. Similarly, the support plate 905 is radially opposed to the spacer 902 when no axial force above the above-mentioned second threshold is acting on the device 22.

[0138] The support plates 904, 905 are interposed between the washers 104, 106 and the radially outer ring 114 of the bearing 900. Thus, in this embodiment, the radial outer periphery 122 of the washers 104, 106 abuts axially against the support plates 904 and 905, respectively. However, the washers 104, 106 indirectly support axially (through the support plates 904, 905) against the radially outer ring 814 of the bearing.

[0139] The support plates 904, 905 are, for example, annular. The axial half-sections of the plates 904, 905 advantageously have an inverted L-shape. This inverted L-shape makes it possible to keep the support plates 904, 905 in place by forcing them between the bearing 900 and the radial periphery 122 of the washers 104 and 106, respectively. It is therefore not necessary to fasten the plates 904, 905 to any component of the device 22. Thus, as will be explained below, the support plate 904 is moved axially when a force greater than a first threshold is applied to the device 22, and the support plate 905 is moved axially when a force greater than a second threshold is applied to the device 22.

[0140] In this embodiment, the first assembly 200 includes the nut 261, the sleeve 801, the closure nut 907, and the spacers 901, 902. The second assembly 300 includes the housing 241, the preload elements 108, 110, and the resilient members 104, 106. Moreover, a first axial clearance 201 exists between the first spacer 901 and the first resilient member 104, while a second axial clearance 301 exists between the second spacer 902 and the second resilient member 106.

[0141] The operation of the device 22 according to the embodiment of Figures 4 and 5 will now be described.

[0142] Under normal operating conditions, the operation of the device 22 of FIGS. 4 and 5 is identical to that of FIGS.

[0143] As shown diagrammatically in FIG. 4 by a dotted curve, when an axial force E3 greater than a first threshold is applied to the screw 28 in a direction toward the nut 261, the force E3 is transmitted from the screw 28 to the nut 261 and the sleeve 801. This causes a movement of the first assembly 200 in the direction of the force E3. The spacer 902 then axially abuts the inner ring 112 of the bearing 900, which causes the transmission of the axial force E3 to the ring 112. The force E3 is transmitted to the outer ring 114 of the bearing 900, which causes the axial movement of the ring 114 in the direction of the force E3. The ring 114 then axially abuts the support plate 904, driving it in translation axially in the direction of the force E3. The elastic member 104 is then axially compressed. The force E3 is then transmitted to the first preload element 108 and is finally dissipated through the housing 241.

[0144] The compression of the elastic member 104 causes the length of the second axial clearance 201 to be reduced until the spacer 901 comes to abut against the elastic member 104. On the one hand, this prevents the axial movement of the first assembly 200 relative to the second assembly 300. On the other hand, due to the friction existing between the axial stop 127 corresponding to the spacer 901 and the complementary axial stop 129 corresponding to the elastic member 104, the rotation of the first assembly 200 about the X-axis is braked.

[0145] As shown diagrammatically in FIG. 5 by a dotted curve, when an axial force E4 greater than a second threshold is applied to the screw 28 in a direction toward the closure nut 907, the force E4 is transmitted from the screw 28 to the nut 261 and the sleeve 801. This causes a movement of the first assembly 200 in the direction of the force E4. The spacer 901 then abuts against the inner ring 112 of the bearing 900, which causes the transmission of the axial force E4 to the ring 112. The force E4 is transmitted to the outer ring 114 of the bearing 900, which causes an axial movement of the ring 114 in the direction of the force E4. The ring 114 then axially abuts against the support plate 905, driving it in translation axially in the direction of the force E4. The elastic member 106 is then axially compressed. The force E4 is then transmitted to the second preload element 110 and is finally dissipated through the housing 241.

[0146] The compression of the elastic member 106 causes the length of the second axial clearance 301 to be reduced until the spacer 902 comes to abut against the elastic member 106. On the one hand, this prevents the axial movement of the first assembly 200 relative to the second assembly 300. On the other hand, due to the friction existing between the axial stop 173 corresponding to the spacer 902 and the complementary axial stop 129 corresponding to the elastic member 106, the rotation of the first assembly 200 about the X-axis is braked.

[0147] It should be noted that in certain cases, the rotation of the nut 26, 261 is prevented with a sufficient torque in order for the transmission device 22 to operate in the case of overload (meaning when the axial force applied to the device 22 is greater than a first or second threshold value). For this purpose, the transmission device 22, and in particular the nut 26, 261, may be connected to an element that allows braking the nut. For example, the nut may be connected to a friction brake or a motor with a high detent torque (also called cogging torque), among other possibilities. According to the definition accepted by the International Electrotechnical Commission (IEC), cogging torque is "the periodic torque in a non-energized permanent magnet motor due to the tendency of the rotor and stator to align themselves in a position of minimum magnetic resistance".

[0148] The elements enabling braking of the nuts 26, 261 may for example be provided in the reducer mentioned above.

Claims

1. A transmission device (22) for transmitting movement, the device comprising: a screw (28, 281) extending along an axis (X); a nut (26, 261) cooperating with the screw; a housing (24, 241); a first elastic member (104); a second elastic member (106); a first assembly (200) comprising said nut; a second assembly (300) comprising said housing; a first axial stopper (127) axially integral with the first assembly and capable of cooperating with a first complementary axial stopper (129) of the second assembly, wherein a first axial clearance (301) is formed between the first axial stopper (127) and the first complementary axial stopper (129); a second axial stopper (123) axially integral with the first assembly and capable of cooperating with a second complementary axial stopper (125) of the second assembly, wherein a second axial clearance (201) is formed between the second axial stopper (123) and the second complementary axial stopper (125); Equipped with the first resilient member (104) can be deformed independently of the second resilient member (106) under the influence of a first axial force (E1, E3) directed in a first direction and applied to the first resilient member (104) by the first assembly (200), thereby reducing the first axial clearance (301) and causing the first axial stop (127) to abut against the first complementary axial stop (129) when said first axial force (E1, E3) exceeds a first threshold; The second resilient member (106) can be deformed independently of the first resilient member (104) under the influence of a second axial force (E2, E4) directed in a second direction opposite to the first direction, the second axial force (E2, E4) being applied to the second resilient member (106) by the first assembly (200), thereby reducing the second axial clearance (201) and causing the second axial stop (123) to abut against the second complementary axial stop (125) when said second axial force (E2, E4) exceeds a second threshold value, transmission device (22).

2. 2. The transmission device (22) of claim 1, further comprising a first preload element (108) and a second preload element (110), wherein the first preload element can adjust a preload stress acting on the first resilient member (104) independently of a preload stress acting on the second resilient member (106), and the second preload element can adjust a preload stress acting on the second resilient member (106) independently of a preload stress acting on the first resilient member (104).

3. 3. A transmission device (22) according to claim 2, comprising at least one bearing (100, 102, 900) comprising a radially inner ring (112) arranged facing the first assembly (200) and a radially outer ring (114) arranged facing the second assembly (300), wherein the radially outer periphery (122) of each elastic member (104, 106) is adapted to abut axially, directly or indirectly, against the radially outer ring (114) of said bearing, and the radially inner periphery (121) is adapted to abut axially against the preload element (108, 110).

4. 4. The transmission device (22) of claim 3, wherein the second assembly (300) comprises a shoulder (40) extending radially from the radially inner wall (36) of the housing (24, 241), the first elastic member (104) being disposed on a first side of the shoulder (40) of the second assembly (300), and the second elastic member (106) being disposed on a second side of the shoulder (40) of the second assembly (300) opposite the first side.

5. 5. The transmission device of claim 4, wherein the first bearing is disposed between the first elastic member and a first side of the shoulder of the second assembly, and the second bearing is disposed between the second elastic member and a second side of the shoulder of the second assembly, such that a radial outer periphery of the first elastic member abuts axially against a radial outer ring of the first bearing, and a radial outer periphery of the second elastic member abuts axially against a radial outer ring of the second bearing.

6. 5. The transmission device (22) of claim 4, wherein the first assembly (200) comprises a shoulder (92) extending radially from a radially outer wall (85) of the first assembly (200), the shoulder (92) of the first assembly (200) being positioned radially facing the shoulder (40) of the second assembly (300).

7. 7. The transmission device (22) of claim 6, wherein the shoulder (92) of the first assembly (200) has an axial length that is shorter than the axial length of the shoulder (40) of the second assembly (300).

8. The transmission device (22) of claim 4, wherein the bearing (900) is disposed radially inward of the shoulder (40) of the second assembly (300).

9. 6. The transmission device (22) of claim 5, further comprising a first annular support plate (904) arranged between the radially outer ring (114) of the bearing (900) and the radially outer periphery (122) of the first elastic member (104), and a second annular support plate (905) arranged between the radially outer ring (114) of the bearing (900) and the radially outer periphery (122) of the second elastic member (106), wherein the radially outer periphery (122) of the first elastic member (104) abuts against the first support plate (904) and the radially outer periphery (122) of the second elastic member (106) abuts against the second support plate (905).

10. 10. An aircraft seat (2) comprising a fixed part intended to be fixed to a fixed part of an aircraft and a movable part movable relative to the fixed part, wherein a transmission device (22) for transmitting a movement according to any one of claims 1 to 9 is attached between the movable part and the fixed part, a nut (26, 261) of the transmission device being rotatable by an actuator (20), a screw (28, 281) being connected to the movable part of the seat (2), and a housing (24, 241) being connected to the fixed part of the seat (2).

11. A transmission device (22) as described in claim 5, wherein the first assembly (200) has a shoulder (92) extending radially from the radial outer wall (85) of the first assembly (200), and the shoulder (92) of the first assembly (200) is positioned radially facing the shoulder (40) of the second assembly (300).

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