Aircraft seat

An aircraft seat includes an actuator and a movement transmission device. The movement transmission device includes a frame having at least one bearing face and one braking face; a drive body configured to being rotated relative to the frame, the drive body having a bearing face and a braking face; and an elastic element suitable for keeping the braking face of the drive body at a defined distance from the braking face of the frame, the elastic element having a determined stiffness and being prestressed such that, when an axial load greater than a threshold load is applied to the drive body, the braking face of the drive body comes into contact with the at least one braking face of the frame.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/FR2020/052116, filed Nov. 18, 2020, which claims priority to French Patent Application No. 1913133, filed Nov. 22, 2019, the entire disclosures of which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD OF THE DISCLOSURE

Embodiments of this disclosure relate to the field of aircraft seats.

BACKGROUND

In an aircraft, the seats can be moved relative to the ground by drive systems. These drive systems include an actuator and a transmission chain. The mechanical parts of these drive systems must be able to withstand loads corresponding to a sudden stop situation (generally called a “crash”) without the mechanical parts breaking and possibly injuring a passenger. The seat must therefore withstand thrusts of 9 to 16 g during a sudden stop. These mechanical parts must also be able to withstand sudden significant and repeated loads, experienced for example when the aircraft regains lift after passing through an air pocket or when an obese person drops violently on the seat. When faced with these situations, the mechanical parts of the transmission chain must neither break nor wear out prematurely, in order to limit the number of ground stops for maintenance purposes.

To achieve this objective, the mechanical parts of aircraft drive systems are overdesigned. However, this overdesign increases both the manufacturing cost of the mechanical parts and the weight of the aircraft. It is desirable to reduce the weight of the aircraft in order to reduce the amount of kerosene required to complete a given trip, and thus limit the cost of air transport and preserve the environment.

It is also known, for example from document WO 2015/104378, to insert a mechanism for locking and unlocking the kinematic drive chain of a seat element. Embodiments of the disclosure improve the situation.

SUMMARY

The disclosure relates to an aircraft seat comprising at least one actuator capable of generating movement and at least one movement transmission device comprising:a frame provided with a through-bore extending in an axial direction, the frame comprising at least one bearing face and at least one braking face;a drive body suitable for being rotated relative to the frame about an axis extending in an axial direction, the drive body being arranged in the bore to move freely in translation along at least the axial direction relative to the frame, the drive body comprising at least one bearing face extending facing the bearing face of the frame and at least one braking face extending facing at least part of the braking face of the frame; andat least one elastic element arranged between the at least one bearing face of the frame and the at least one bearing face of the drive body in order to keep the at least one braking face of the drive body at a defined distance from the at least one braking face of the frame, the at least one elastic element having a determined stiffness and being prestressed such that, when an axial load greater than a threshold load is applied to the drive body, the elastic element is compressed and the at least one braking face of the drive body comes into contact with the at least one braking face of the frame.

The aircraft seat according to the disclosure comprises a transmission device which makes it possible to counter an excessively large force so that the actuator and the mechanical parts of the transmission system do not need to withstand this force. Countering this force is carried out through a dedicated path of operation and eliminates the need to overdesign the normal path of operation.

Advantageously, the transmission device is a purely mechanical system which does not require any external supply of energy. It does not require a control and execution system in order to operate. The transmission device is inserted into any rotary transmission system and does not interfere with its operation. Due to its locking servo function as well as its adaptability, the transmission device of the aircraft seat allows designing the actuator and the mechanical parts of the transmission system and ultimately allows savings in weight and/or a reduction in the technical requirements of the main transmission function.

The features set forth in the following paragraphs may optionally be implemented. They may be implemented independently of each other or in combination with each other.

The elastic element comprises at least one spring washer;

The elastic element comprises two Belleville washers mounted in opposition to each other;

The transmission device comprises at least one bearing arranged between the bearing face of the frame and the at least one elastic element;

The drive body comprises a ball screw nut, a ball screw suitable for being driven in translation by the ball screw nut, a cylindrical casing which lies in the extension of the ball screw nut, the cylindrical casing comprising a first end integral with the ball screw nut and a second free end, and a radial wall integral with at least one end of the cylindrical casing, the at least one braking face and the at least one bearing face of the drive body being arranged on the radial wall;

The seat comprises a closure nut suitable for being made integral with the second end of the cylindrical casing, the closure nut being capable of prestressing the at least one elastic element;

The braking face and bearing face of the drive body are arranged on a radial face of the closure nut;

The cylindrical casing comprises a crown extending axially from the end of the radial wall, the crown being able to be fixed to the ball screw nut;

The frame comprises at least one internal shoulder contained in a first radial plane and at least one peripheral shoulder arranged around the at least one internal shoulder and contained in a second radial plane, the second radial plane being offset axially relative to the first radial plane; and the at least one bearing face of the frame is formed by the at least one internal shoulder and the at least one braking face of the frame is formed by the at least one peripheral shoulder.

The transmission device comprises a support ring arranged around the cylindrical casing, the support ring forming the radial wall, the bearing face of the drive body being a radial face of the support ring.

The support ring is provided with a peripheral flange extending axially, the end face of the peripheral flange forming the braking face of the drive body.

The frame comprises a bearing face extending radially, and the transmission device comprises a bearing and a thrust washer which are arranged in the bore around the drive body; the bearing having an inner ring and an outer ring, the outer ring of the bearing resting against the bearing face of the frame, the thrust washer resting against the inner ring of the bearing.

The transmission device further comprises a braking ring provided with a skirt extending radially inwards, a radial face of the skirt being arranged facing the braking face of the drive body, a portion of the radial face of the skirt forming the braking face of the frame.

DETAILED DESCRIPTION

The drawings and the description below contain elements that for the most part are certain in nature. Therefore not only may they serve to provide a better understanding of this disclosure, but they may also contribute to its definition where appropriate.

Referring toFIG.1, an example of an aircraft seat2according to the disclosure is represented. It comprises a seat base4, a backrest6pivotally mounted relative to the seat base4, a headrest8pivotally mounted relative to the backrest6, a leg rest10, feet12, and slides14fixed to the floor. The feet12of the seat are capable of sliding in the slides14in order to move the seat2forwards or backwards. The seat2has an electric drive system18dedicated to moving the seat2in the slides. The drive system18comprises, for example, an actuator20, a transmission device22for transmitting the movement generated by the actuator, and mechanical parts suitable for transmitting the movement to the feet12of the seat. These mechanical parts include, for example, gears, connecting rods, a rack, etc. These are not represented in the FIGURES.

The present patent application is described with reference to an orthogonal frame of reference (O, x, y, z) represented inFIGS.2and3. In this frame of reference, the axial direction is defined by the x direction, the radial plane is defined by the (y, z) frame of reference.

In the present patent application, the term “input23” designates the side of the transmission device receiving the driving movement and located towards the actuator20. The term “output24” designates the side of the transmission device transmitting the drive movement and located towards the feet12of the seat.

Referring toFIGS.3and5, the transmission device22according to a first embodiment comprises a frame26including a through-bore32extending in an axial direction x, a drive body28arranged in the bore32of the frame and first30and second31elastic elements housed in the bore32of the frame.

The frame26is provided, on the input23side, with a first internal shoulder25and a first peripheral shoulder27arranged in the bore32. The first internal shoulder25has a first bearing face34contained in a first radial plane P1. The first peripheral shoulder27has a first braking face36contained in a second radial plane P2. The second radial plane P2is arranged at a distance d1from the first radial plane P1in the axial direction. The first radial plane P1is parallel to the second radial plane P2. The first peripheral shoulder27is arranged outside of and around the first internal shoulder25. The vector normal to the first bearing face34is oriented towards the input23, or in other words along the −x direction in the frame of reference (O, x, y, z) illustrated inFIG.3.

The frame26is also provided, on the output24side, with a second internal shoulder33and a second peripheral shoulder35. The second internal shoulder33has a second bearing face38contained in a third radial plane P3. The second peripheral shoulder35has a second braking face40. The second braking face40is contained in a fourth radial plane P4arranged at a distance d3from the third radial plane P3in the axial direction. The fourth radial plane P4is parallel to the third radial plane P3, second radial plane P2, and first radial plane P1. The second peripheral shoulder35is located outside of and around the second internal shoulder33. The vector normal to the second bearing face38is oriented towards the output24, or in other words along the x direction of the frame of reference (O, x, y, z) illustrated inFIG.3.

The drive body28is freely movable in translation along at least the axial direction (x) relative to the frame26.

The drive body28comprises a ball screw nut42suitable for being rotated by an actuator20(or a drive pinion) about an axis extending in the axial direction, a ball screw44driven in translation in the axial direction by the ball screw nut42, and a support and braking sleeve46capable of being made integral with the ball screw nut42.

The support and braking sleeve46comprises a cylindrical casing48having a first end54located on the input side23and a second free end56located on the output side24. The outer face of the second end56of the cylindrical casing is threaded. The cylindrical casing48lies in the extension of the ball screw nut42. The cylindrical casing48is carried by the frame26. It can move freely in rotation and in translation relative to the frame26. It houses part of the ball screw44.

The support and braking sleeve46further comprises a radial wall50extending around the first end54of the cylindrical casing and a crown52extending axially from the radial wall50.

The radial wall50is integral with the cylindrical casing. It extends outwards and forms a collar. The radial wall50extends facing the first bearing face34of the frame and at least a portion of the first braking face36of the frame. The end of one face of the radial wall forms a first braking face55of the drive body. This first braking face55of the drive body is located facing the first braking face36of the frame. A portion of this radial face of the radial wall50located facing the internal shoulder34forms the first bearing face62of the drive body.

The crown52is suitable for being fixed to the ball screw nut42. For this purpose, the internal face of the crown52and the external face of the ball screw nut42are provided with complementary attachment means such as, for example, internal and external threads.

The support and braking sleeve46further comprises a closure nut57fixed to the second end56of the cylindrical casing, for example by screwing. The closure nut57has an axial section of triangular shape. It is screwed onto the second end56of the cylindrical casing. The closure nut57is screwed in a manner that prestresses the elastic elements30,31. The closure nut57preloads the elastic elements30,31. They are tightened so as to set a relaxation threshold to a given force. This given force is called the threshold load in the remainder of the description. The closure nut forms a radial wall59. A radial face of the closure nut is arranged facing the second bearing face38of the frame. A portion of this radial face forms a second bearing face65of the drive body. Another portion of this radial face, located opposite the second braking face40of the frame, forms the second braking face63of the drive body.

Advantageously, the transmission device22comprises at least one bearing arranged between the frame26and the drive body28.

In the embodiment shown, the transmission device22comprises a first bearing60arranged in the bore32between the first bearing face34of the frame and elastic element30. The transmission device22also comprises a second bearing61arranged in the bore32between the second bearing face38of the frame and elastic element31. Preferably, the transmission device22comprises a third hollow cylindrical bearing58arranged in the bore32between the first bearing face34of the frame and the second bearing face38of the frame.

The first bearing60and second bearing61are, for example, composed of needle bearings. The third cylindrical bearing58is, for example, composed of a cage needle bearing.

The first elastic element30is capable of acting between the first bearing face34of the frame and the first bearing face62of the drive body. In particular, in the embodiment represented, the first elastic element30is arranged between the first bearing face34of the frame and the first bearing face62of the drive body.

The second elastic element31is capable of acting between the second bearing face38of the frame and the second bearing face65of the drive body. In particular, in the embodiment represented, the second elastic element31is arranged between the second bearing face38of the frame and the second bearing face65of the drive body.

When the first elastic element30is at rest, the first bearing face62of the drive body extends at an axial distance d2from the first bearing face34of the frame. The axial distance d2is equal to the height of the first elastic element30at rest plus the axial width of the first bearing60.

Similarly, when the second elastic element31is at rest, the second bearing face65of the drive body extends at an axial distance d4from the second bearing face38of the frame. The axial distance d4is equal to the height of the second elastic element31at rest plus the axial width of the second bearing61.

In the embodiment shown, the first elastic element30comprises two spring washers, for example of the Belleville washer type66,68, mounted in opposition to one another around the cylindrical casing48. The central portion (raised portion) of one spring washer68bears against radial wall50. The central portion (raised portion) of the other spring washer66bears against the first bearing60.

In the same manner, the second elastic element31comprises two spring washers, for example of the Belleville washer type70,72, mounted in opposition to one another around the cylindrical casing48. The central portion (raised portion) of one spring washer72bears against radial wall59. The central portion (raised portion) of the other spring washer70bears against the second bearing61.

The first30and second31elastic elements each have a stiffness determined according to a threshold load at which the user wishes the transmission device22to brake or stop the movement of the ball screw44.

Alternatively, the first elastic element30consists of a single Belleville washer and the second elastic element30consists of a single Belleville washer.

Alternatively, the first elastic element30and the second elastic element31are different from each other. In particular, they may have different stiffness coefficients.

Alternatively, the ball screw nut42and the support and braking sleeve46are formed as one piece.

Alternatively, the distances d1and d3and/or the distances d2, d4are different from each other.

In operation, the drive body28is rotatable relative to the fixed frame26. The actuator20drives the rotation of the ball screw nut42and the drive body28integral with the ball screw nut42. The ball screw nut42drives the ball screw44in translation. The drive body28is rotatable relative to the fixed frame26.

When an axial load Cs is applied to the ball screw44in a direction oriented towards the output24, the first elastic element30is compressed. The axial load Cs has a direction opposite to the vector normal to the first bearing face34of the frame (x direction in the frame of reference illustrated inFIG.3). The axial load Cs is external to the transmission device22. It is greater than a threshold load. The first elastic element30is compressed by an axial distance at least equal to the difference between distance d2and distance d1. The difference between distance d2and distance d1forms a defined distance Dd. The first braking face55of the drive body comes into contact with the first braking face36of the frame. The first braking face55of the drive body rubs against the first braking face36of the frame and thereby slows the rotation of the drive body28.

Similarly, when an axial load Ce is applied to the ball screw44in a direction oriented towards the input23, the second elastic element31is compressed. The axial load Ce has a direction opposite to the vector normal to the second bearing face38of the frame (−x direction in the frame of reference illustrated inFIG.3). The axial load Ce is external to the transmission device22. It is greater than a threshold load. The second elastic element31is compressed by an axial distance at least equal to the difference between distance d4and distance d3. The second braking face63of the drive body comes into contact with the second braking face40of the frame. The second braking face63rubs against the second braking face40of the frame and thereby slows the rotation of the drive body28.

Thus, in the event of sudden loads being applied, corresponding to an emergency stop or to people sitting down heavily, the support and braking sleeve46rubs against the frame26and absorbs part of the impact, thus protecting the kinematic chain of the seat. The transmission device22is capable of slowing the driving of the ball screw44regardless of the direction of the external load applied to the transmission device.

The disclosure also relates to an aircraft seat2comprising a transmission device74according to a second embodiment of the disclosure. This transmission device74is similar to the transmission device22according to the first embodiment except that it is suitable for braking the driving of the ball screw only when loads having a given direction are applied to the device.

FIGS.4and5show an example of such a transmission device74capable of slowing the driving of the ball screw only for loads Ce directed towards the input (−x direction with respect to the frame of reference (O,x,y,z).

The elements of the transmission device74according to the second embodiment which are identical or similar to the elements of the transmission device22according to the first embodiment bear the same references and are not described a second time.

The transmission device74comprises a frame261and a drive body281. The frame261includes an internal shoulder73located in the bore32. The internal shoulder73forms a bearing face75which extends radially relative to the axial direction x. The drive body281includes a ball screw nut421which is extended axially by a cylindrical casing481housing part of the ball screw44.

The transmission device74further comprises a bearing581and a thrust washer81which are arranged in the bore32around the cylindrical casing481. The bearing581comprises an outer ring bearing against the bearing face75and an inner race, the inner ring being able to rotate with the drive body281. The thrust washer81bears against the inner ring of the bearing.

The transmission device74further comprises a braking ring76suitable for being made integral with the frame. The braking ring76comprises a skirt79extending radially inwards to the thrust washer81. The skirt79bears against the edge of the thrust washer81and lies in the extension thereof. A portion of the radial face of the skirt79forms the braking face83of the frame. In the embodiment shown, the braking ring76is screwed into the bore32of the frame261. For this purpose, the braking ring76comprises an external thread and the bore is provided with an internal thread.

The transmission device74further comprises an elastic element301, a support ring78, and a closure nut57that is fixed to the free end561of the cylindrical casing481, for example by screwing.

The support ring78is force-fitted around the cylindrical casing481. The support ring78is driven in rotation by the drive body. The support ring78extends radially around the axial direction x. It forms a radial wall380. The elastic element301bears against a radial face of the support ring78. This radial face is a bearing face84of the drive body.

The support ring78is provided with a peripheral flange82. The peripheral flange82extends axially towards the skirt79of the brake ring. The end face of the peripheral flange forms a braking face86of the drive body. The braking face86of the drive body extends facing the braking face of the frame.

The elastic element301is arranged in the housing formed by the support ring78and the peripheral flange82. The height of the elastic element301at rest is greater than the axial length of the flange82such that the braking face86of the drive body is arranged at a defined distance Dd from the braking face of the frame when the elastic element301is at rest.

The elastic element301is for example composed of a spring washer of the Belleville washer type. The central portion (raised portion) of the elastic element301bears against the thrust washer81. The peripheral edge of the elastic element301bears against the peripheral flange82.

The degree of screwing of the closure nut57on the free end561of the cylindrical casing481makes it possible to adjust the threshold for triggering the flattening of the elastic element301.

Alternatively, the elastic element301comprises two spring washers mounted in opposition, for example two Belleville washers.

In operation, the ball screw nut421is driven in rotation by the actuator20so as to drive the ball screw44in translation. The closure nut57, the support ring78, the elastic element301, the thrust washer81, and the inner ring of the bearing581are driven in rotation.

When an axial load Ce greater than a threshold load is applied to the ball screw44, the elastic element301flattens. The braking face86of the drive body comes into contact with the braking face83of the frame. The braking face of the drive body rubs against the braking face83of the frame and slows down or stops the rotation of the ball screw nut.

Alternatively, the disclosure also relates to devices capable of braking the driving only for loads Cs directed towards the output (−x direction with respect to the frame of reference (O,x,y,z).