Y-shaped elevation system for aircraft seats and method for deforming such an elevation system

Abstract

An aircraft seat elevation system, the elevation system comprising a support base having a right side portion and a left side portion, a first frame having a lower end mounted pivoting and sliding within the support base and an upper end configured to be connected to the seat, and a second frame having a lower end mounted pivoting with the support base and an upper end configured to be connected to the seat, the first and second frames being articulated about a lateral axis so as to pivot relative to each other, the second frame comprising a left arm and a right arm. The elevation system includes a linking member connecting the left and right side portions of the support base, the lower ends of the arms of the second frame being directly connected to the linking member. (Shortcut Figure: Figure 6)

Description

Title of the invention: Y-shaped elevation system for an aircraft seat and method of deforming such an elevation system Technical field

[0001] The present invention relates to the field of aircraft seats and more particularly relates to systems for raising pilot seats fixed to a structure of the aircraft.

[0002] As is known, every person in an aircraft sits on a seat that ensures their safety, for example in the event of an impact. In particular, the pilot and co-pilot of an aircraft are generally seated on seats called "pilot seats".

[0003] With reference to [Fig. 1], a pilot seat S comprises, in a known manner, a substantially horizontal seat and a substantially vertical backrest for supporting a pilot. The pilot seat S is mounted along a longitudinal axis X, a lateral axis Y and a vertical axis Z, so as to form an orthogonal reference frame (X, Y, Z). Subsequently, the terms "front" and "rear" refer to the longitudinal axis X which extends from back to front in the direction of positioning of the seat facing the front of the aircraft. Similarly, the terms "left" and "right" are understood to refer to the lateral axis Y which extends from right to left for a pilot seated in the seat S facing the front of the aircraft. Finally, the terms "top" and "bottom" refer to the vertical axis Z which extends from bottom to top.

[0004] The pilot seat S is connected to the floor P of the aircraft by means of two longitudinal rails RI, R2, fixed to the floor P, and a lifting system 100, mounted in the longitudinal rails RI, R2. The two longitudinal rails RI, R2 allow the pilot to slide the seat S back and forth to allow him, on the one hand, to access the cockpit and, on the other hand, to adjust its position, as is the case for example for a driver's seat in a car.

[0005] In a known manner, the elevation system 100 is connected, on the one hand, to the longitudinal rails RI, R2 and, on the other hand, to the pilot seat S and makes it possible to adjust the vertical position (height) of the seat S to the size of each pilot. In addition, the seat base S is mounted on the elevation system 100 so as to allow lateral movement of the seat S, to facilitate access to and exit from the seat S.

[0006] In summary, the elevation system 100 mounted on the longitudinal rails RI, R2 allows longitudinal, lateral and vertical adjustment of the position of the pilot's seat S so as to precisely position the pilot's eye and allow him to have an optimal field of vision for piloting the aircraft.

[0007] In order to allow such adjustments, a known elevation system 100 (shown in Figures 2 to 4) comprises a support base 120 extending in the plane (X, Y), connected to the longitudinal rails RI, R2. The support base 120 slides relative to the longitudinal rails RI, R2 so as to modify the longitudinal position of the seat S. The elevation system 100 further comprises a first frame 130 and a second frame 140 which are articulated together around a transverse axis Yl, so as to pivot relative to each other, like a pair of scissors.

[0008] In practice, as shown in [Fig. 3], the support base 120 comprises a right lateral part 121 and a left lateral part 122. The first frame 130, in one piece, comprises a right arm 131 and a left arm 132 and the second frame 140 comprises a separate right arm 141 and left arm 142. The right arms 131, 141 of the first frame 130 and the second frame 140 are mounted directly in the right lateral portion 121 of the support base 120. Similarly, the left arms 132, 142 of the first frame 130 and the second frame 140 are mounted directly in the left lateral portion 122 of the support base 120. In other words, two arms 131, 141 belonging to different frames 130, 140 are mounted directly in a lateral portion 121, 122 of the support base 120.

[0009] As is known, a pilot seat must meet several requirements to ensure the safety of the pilot. Such requirements are referenced in standards known to those skilled in the art and published by aeronautical certification authorities. In practice, a pilot seat must be able to withstand high accelerations, corresponding to the accelerations to which the pilot is subjected in the critical conditions of a crash. The pilot seat must also be able to withstand deformations of the floor caused by this same crash. In other words, it is necessary for the fixings of the pilot seat on the floor to withstand the forces generated by the accelerations after they have been deformed, as described in document FR2983135.

[0010] In practice, a pilot seat must withstand an acceleration corresponding to a crash case (16G dynamic forward) under precise conditions of lateral and vertical twisting of the longitudinal rails corresponding to the deformation of the structure of the aircraft on which the seat is fixed. Such twisting is known to those skilled in the art under the designation "pitch and roll" and corresponds to the pivoting (deformation) of one of the longitudinal rails along the vertical axis and the pivoting of the second rail along the lateral axis.

[0011] However, the elevation system as known in the prior art generates significant forces in the fasteners, resulting in significant pre-stresses in the various parts, which presents a significant drawback. During the qualification test, additional forces are added to the pre-stresses, which can affect the mechanical strength of the system.

[0012] In practice, during the deformation of the floor P, the lateral parts 121, 122 of the support base 120 are deformed significantly, these deformations pass into the arms 131, 132, 141, 142 of the frames 130, 140, which induces significant mechanical forces in the frames 130, 140 and their fixings. Such mechanical forces are all the more significant as the longitudinal rails RI, R2 are spaced apart by a reduced distance, generally less than 300 mm.

[0013] To meet the requirements, it is then necessary to significantly reinforce each part of the elevation system 100 and the fixings which connect it to the longitudinal rails RI, R2 and to the seat base S, which significantly increases the mass and complexity of the elevation system. Indeed, the balance between sufficient stiffness to support crash loads and the flexibility necessary to absorb deformations due to twisting of the floor is complex to determine.

[0014] The invention thus aims to eliminate at least some of these drawbacks by proposing a reliable seat elevation system allowing both adjustment of the seat position while limiting the forces and constraints in the system, in particular during floor twists. PRESENTATION OF THE INVENTION

[0015] The invention relates to an elevation system for an aircraft seat, the aircraft comprising a floor and two longitudinal rails extending along a longitudinal axis, the two longitudinal rails being fixed to the floor, the elevation system being configured to adjust the position of the seat relative to the floor of the aircraft, the elevation system comprising: • a support base configured to be mechanically connected to the longitudinal rails, the support base comprising a right lateral part and a left lateral part, the support base being configured to slide along the longitudinal rails, so as to move the seat along the longitudinal axis, • a first frame comprising a lower end pivotally and slidably mounted in the support base and an upper end configured to be connected to the seat, • a second frame comprising a lower end pivotally mounted with the support base and an upper end configured to be connected to the seat, the first frame and the second frame being articulated about a lateral axis so as to pivot relative to each other, the second frame comprising a right arm and a left arm.

[0016] The elevation system is remarkable in that it comprises a connecting member connecting the right side part and the left side part of the support base, each arm of the second frame having a lower end, the lower ends of the arms are connected directly to the connecting member.

[0017] The connecting member makes it possible to mechanically connect each arm of the second frame and the support base indirectly. During a crash, the pilot, thrown forward and installed in the seat, causes significant forces in the elevation system and therefore in the longitudinal rails and the floor. The connecting member, independent of the support base, makes it possible to absorb part of the forces which pass through the frames of the elevation system. Also, the lower end of the second frame transmits less force to the longitudinal rails. In summary, thanks to the invention, less force passes through the parts and fixings of the elevation system. It is therefore not necessary to reinforce it, which allows for a less complex and lighter elevation system, which is important given the mass problem inherent in the aeronautical field.

[0018] During a qualification test of the pilot seat comprising high accelerations in particular conditions of twisting of the floor (known to those skilled in the art under the term "pitch and roll") and therefore of torsion of the support base, a significant part of the forces resulting from the twisting is absorbed by the connecting member, thus advantageously limiting their transmission to the rest of the parts of the elevation system and to the interfaces with the rails.

[0019] Preferably, the right arm and the left arm of the second frame are connected to the connecting member in the same central zone of the connecting member. The assembly formed by the two frames is thus connected to the support base substantially at three connection points, making the elevation system isostatic, which represents a particularly advantageous mechanical configuration in terms of transmission of forces (in particular compared to a configuration according to the hyperstatic prior art), since it makes it possible to limit overly constrained connections and therefore greater forces in the bindings.

[0020] Preferably, the central zone of the connecting member is equidistant from the lateral parts of the support base. The few forces which pass through the connection between the second frame, the connecting member and the support base are thus equally distributed between the right lateral part and the left lateral part of the support base, which allows for equivalent stresses both between the two parts of the support base and between the two arms of the second frame. In other words, such a configuration makes it possible to distribute the stresses and forces evenly on either side of the central zone and therefore to limit the risk of over-stressing of a part or a fixing with respect to the others of the lifting system.

[0021] Preferably, the lower end of the right arm and the lower end of the left arm are adjacent, forming a single leg to the second frame, which ensures a single connection point between the second frame and the connecting member. A single leg ensures an isostatic elevation system, which allows minimal forces to be transmitted to the support base and the seat base, as well as to the fixings that connect the elevation system to the pilot seat and the longitudinal rails.

[0022] Preferably, the lower end of the right arm and the lower end of the left arm are in contact, ensuring a single connection point between the second frame and the connection member. The elevation system is thus advantageously isostatic, which allows a minimum of forces to pass through the elevation system and into the seat base.

[0023] Preferably, the right lateral portion and the left lateral portion of the support base are spaced apart by a distance of between 200 and 350 mm, allowing the mounting of the elevation system on longitudinal rails of the prior art, usually mounted on an aircraft floor.

[0024] Preferably, the connecting member is in the form of a transverse tube extending between the right lateral part and the left lateral part of the support base, allowing a simple connection both between the connecting member and the support base and between the connecting member and the second frame. A tube also makes it possible to release the degrees of freedom which make it possible to limit the transmission of forces between the parts of the elevation system and with the seat of the pilot seat and the longitudinal rails.

[0025] Preferably, the lifting system comprises a single connecting member connecting the right lateral part and the left lateral part of the support base, the lower ends of the arms of the second frame are connected directly to the single connecting member. A single connecting member makes it possible to limit the number of parts and fixings in the lifting system, which makes it possible to ensure a simple lifting system while limiting the forces and stresses which pass through the lifting system.

[0026] Preferably, the second frame is connected to the connecting member by a sliding pivot connection. The rotation of the second frame with respect to the connecting member makes it possible to release a degree of freedom, contributing to the isostatic elevation system, since it makes it possible to avoid several additional blockages and therefore significant additional forces.

[0027] Preferably, each arm of the second frame comprises at least one upper portion and one intermediate portion, the intermediate portion forming with the upper portion an angle of inclination strictly greater than 0°. Such an angle of inclination makes it possible to ensure a second frame whose upper ends and lower ends of each arm are not aligned, which makes it possible to bring the lower ends of the two arms of the second frame together in a common central area.

[0028] Preferably, the angle of inclination is strictly greater than 10°, so as to ensure that the upper ends and the lower ends of each arm are not aligned.

[0029] Preferably, the angle of inclination is between 10° and 40°, which allows the elevation system to be taken up at two connection points on the base of the pilot's seat and at a single point on the connection member, giving the second frame a Y shape, ideal for making the elevation system isostatic and thus limiting the transmission of forces in the elevation system and in the seat, in particular during a crash case qualification test, as described in this document.

[0030] The invention also relates to a set of two longitudinal rails, configured to be fixed to a floor of an aircraft, and to a lifting system as described previously, the support base of the lifting system being mechanically connected to the longitudinal rails.

[0031] The invention further relates to a set of two longitudinal rails, configured to be fixed to a floor of an aircraft, a seat and a lifting system as described above, the support base of the lifting system being connected to the longitudinal rails and the upper end of the first frame and the upper end of the second frame being mechanically connected to the seat.

[0032] The invention also relates to an aircraft comprising a floor and a set of two longitudinal rails, a seat and a lifting system as described above, the two longitudinal rails being fixed to the floor.

[0033] The invention finally relates to a method of deforming a set of two longitudinal rails and a lifting system as described previously, the support base of the lifting system being mechanically connected to the longitudinal rails, the method comprising a step of deforming a first longitudinal rail along a first deformation axis and a second longitudinal rail along a second deformation axis, orthogonal to the first deformation axis. PRESENTATION OF FIGURES

[0034] The invention will be better understood on reading the description which follows, 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.

[0035] [Fig.l] is a schematic representation of a pilot seat mounted on an aircraft floor via a prior art elevation system.

[0036] [Fig.2] is a schematic representation of the elevation system of the art front mounted on two longitudinal rails.

[0037] [Fig. 3] is a close-up, perspective view from the front of the elevation system of [Fig. 2].

[0038] [Fig.4] is a schematic representation of a first frame and a second frame of the prior art elevation system of [Fig.2].

[0039] [Fig.5] is a schematic representation of a pilot seat connected to a floor of an aircraft by two longitudinal rails and a lifting system according to the invention.

[0040] [Fig.6] is a schematic representation, in perspective from the front, of the elevation system of [Fig.5] according to one embodiment of the invention, the elevation system being mounted on the two longitudinal rails.

[0041] [Fig.7] is a schematic representation of an actuator and cylinders mounted on the elevation system of [Fig.6].

[0042] [Fig.8] is a schematic representation of a support base of the elevation system of [Fig.6].

[0043] [Fig.9] is a schematic representation of a first frame of the system elevation of [Fig.6].

[0044] [Fig. 10] is a schematic representation of a perspective view from the rear of the elevation system of [Fig.6].

[0045] [Fig. 11] is a close-up view of the first frame and the second frame of the elevation system of [Fig. 10].

[0046] [Fig. 12] is a schematic representation of the second frame of [Fig. 10] viewed from the front.

[0047] 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. DETAILED DESCRIPTION OF THE INVENTION

[0048] The invention is described in this document with reference to a system for raising a seat intended to accommodate a pilot or a co-pilot in an aircraft, however it goes without saying that it applies to any type of aircraft and to any type of aircraft seat, in particular, a passenger seat.

[0049] As described above, the pilot and co-pilot of an aircraft are generally seated in pilot seats, ensuring their safety. Hereinafter, for the sake of clarity, the pilot seat will be described for use by a pilot.

[0050] As is known, with reference to [Fig. 5], a pilot seat S comprises a substantially horizontal seat and a substantially vertical backrest for supporting a pilot. The seat of the seat S is connected to a floor P of the aircraft by means of a lifting system 1 according to the invention. The lifting system 1 makes it possible to adjust the position of the seat S relative to the floor P, as will be described in more detail later.

[0051] Still with reference to [Fig. 5], the elevation system 1 is mounted along a longitudinal axis X, a lateral axis Y and a vertical axis Z, so as to form an orthogonal reference frame (X, Y, Z). Subsequently, the terms "front" and "rear" refer to the longitudinal axis X which extends from the rear to the front following the positioning direction of the seat facing the front of the aircraft. Similarly, the terms "left" and "right" are understood to be along the lateral axis Y which extends from the right to the left for a pilot seated in the seat S facing the front of the aircraft. The terms "up" and "down" refer to the vertical axis Z which extends from the bottom to the top. Finally, the term "horizontal" describes an object which extends in the plane (X, Y).

[0052] As shown in [Fig. 5], the elevation system 1 is connected to the floor P by means of two longitudinal rails RI, R2 which extend along the longitudinal axis X and are fixed to the floor P of the aircraft. In other words, the elevation system 1 is connected, on the one hand, to the longitudinal rails RI, R2, and, on the other hand, to the seat of the pilot seat S. The longitudinal rails RI, R2 make it possible to adjust the longitudinal position of the seat S, as will be described in more detail later.

[0053] Preferably, the two longitudinal rails RI, R2 are spaced apart by a reduced distance, preferably less than 300 mm.

[0054] With reference to [Fig.6], the elevation system 1 according to the invention comprises a support base 2, connected to the longitudinal rails RI, R2, a first frame 3, a second frame 4 as well as a connecting member 5. The first frame 3 and the second frame 4 are articulated around a lateral axis Yl, so as to pivot relative to each other, like a pair of scissors.

[0055] In one embodiment, with reference to [Fig.7], the elevation system 1 comprises an actuator 7, connected, on the one hand, to the first frame 3, and, on the other hand, to the second frame 4 to allow the elevation of the pilot seat S. The actuator 7 is preferably connected to a control lever which makes it possible to control the elevation or lowering of the pilot seat S. Such a mechanism is known to those skilled in the art and will not be described in more detail in this document.

[0056] Still with reference to [Fig.7], the elevation system 1 preferably comprises two damping cylinders 8, making it possible to dampen the descent of the pilot seat S. For this, each cylinder 8 is preferably connected both to the first frame 3 and to the second frame 4. Such cylinders 8 are known to those skilled in the art and their operation will not be described in more detail in this document.

[0057] In this example, the support base 2 (a close-up view of which is shown in [Fig.8]) comprises a right lateral part 21 and a left lateral part 22, the right and left lateral parts 21, 22 being understood relative to the lateral axis Y which extends from right to left.

[0058] Still with reference to [Fig.8], each lateral part 21, 22 is in the form of an elongated body and extends longitudinally along the X axis, the right 21 and left 22 lateral parts are therefore preferably parallel. In this example, the right 21 and left 22 lateral parts are spaced apart by a distance c of between 200 mm and 350 mm.

[0059] In this example, each lateral part 21, 22 comprises an internal slide 23, shown in Figures 6 and 8, to cooperate with the first frame 3. Each internal slide 23 extends longitudinally along the X axis over a length of between 50 mm and 250 mm in order to allow the movement of the first frame 3 as will be presented later.

[0060] With reference to [Fig.8], the support base 2 further comprises in this example a central crosspiece 24 which connects the right lateral portion 21 and the left lateral portion 22 so as to have a substantially H-shape. The central crosspiece 24 makes it possible to connect the two lateral portions 21, 22 while allowing a robust and flexible support base 2. The right lateral portion 21, the left lateral portion 22 and the central crosspiece 24 form a single-piece assembly. The support base 2 also comprises a front portion 25 and a rear portion 26. Thanks to the H-shape, in which each lateral portion 21, 22 comprises two free ends (one free end at the front portion 25 and one free end at the rear portion 26), the support base 2 can be easily deformed without generating any particular overstress, in particular in the case of a seat qualification test as will be presented later.

[0061] The support base 2 preferably comprises two first through holes 01, along the lateral axis Y, at the level of the rear portion 26 on the free end of each lateral part 21, 22 in order to cooperate with the connecting member 5.

[0062] As shown in [Fig. 6], the support base 2 is mechanically connected to the longitudinal rails RI, R2. The support base 2 is configured to slide relative to the longitudinal rails RI, R2, so as to move the seat S along the longitudinal axis X, back and forth. For this purpose, in this example, the support base 2 comprises four sliding carriages 27, forming four sliding connections, two sliding connections (only one of which is shown in [Fig. 6]) between the right lateral part 21 and the right longitudinal rail RI and two between the left lateral part 22 and the left longitudinal rail R2. The sliding carriages 27 are positioned, in this example, under the lateral parts 21, 22. It goes without saying that the number of sliding carriages 27 could be different.

[0063] Such a support base 2 is preferably made of a metallic material and has significant mechanical strength. It goes without saying that the support base 2 could be made of a different material, for example a composite material.

[0064] The support base 2 is mechanically connected to the first frame 3 and to the second frame 4.

[0065] The first frame 3 and the second frame 4 are articulated around a lateral axis Yl, so as to pivot relative to each other, like a pair of scissors, to raise and lower the seat S. Preferably, the frames 3, 4 are made of a metallic material and have significant mechanical strength. It goes without saying that the frames 3, 4 could be made of a different material, for example a composite material.

[0066] Still with reference to [Fig. 6], the first frame 3 of the elevation system 1 according to the invention comprises a lower end 31 pivotally and slidably mounted in the support base 2 and an upper end 3S connected to the pilot seat S. Preferably, the lower end 31 is connected to the front portion 25 of the support base 2 and the upper end 3S is connected to the rear of the seat of the pilot seat S (as shown in [Fig. 5]).

[0067] Preferably, the first frame 130 is in one piece.

[0068] In one embodiment, with reference to [Fig. 9] and [Fig. 10], the first one-piece frame 3 comprises a right arm 31 mechanically connected to the right lateral portion 21 of the support base 2 and a left arm 32 mechanically connected to the left lateral portion 22 of the support base 2. Also, in this example, each arm 31, 32 of the first frame 3 comprises a lower end 311, 312 (shown in [Fig. 9]). In a preferred embodiment, the right arm 31 and the left arm 32 are symmetrical and each have an elongated shape.

[0069] Preferably, with reference to [Fig. 6], the elevation system 1 comprises two guides 33, mounted respectively in the inner slide 23 of the right lateral part 21 and in the inner slide 23 of the left lateral part 22 of the support base 2. The lower end 311, 312 of each arm 31, 32 is connected to one of the guides 33 by a pivot connection, so as to form a pivoting connection between the arms 31, 32 of the first frame 3 and the guides 33, and by a sliding connection (sliding) between the guides 33 and the support base 2. In practice, as shown in [Fig. 1 1], the right arm 31 of the first frame 3 is connected to the support base 2 at a first connection point P1 and the left arm 32 of the first frame 3 is connected to the support base 2 at a second connection point P2. The first connection point PI and the second connection point P2 are preferably separated by a distance a of between 100 and 250 mm.

[0070] In this example, the upper end 3S of each arm 31, 32 of the first frame 3 is connected to the pilot seat S, preferably by pivot connections, so as to allow pivoting between the first frame 3 and the seat S around the lateral axis Y to allow scissor operation. For this, with reference to [Fig. 10], the upper end 3S of each arm 31, 32 of the first frame 3 comprises a second through-hole 02, along the lateral axis Y, allowing the passage of a first crosspiece (not shown), which connects the first frame 3 and the seat base S. Such a crosspiece allows a pivot connection while allowing the lateral sliding of the crosspiece in the second holes 02 of the upper ends 3S of the arms 31, 32 of the first frame 3, making it possible to adjust the lateral position of the seat S along the lateral axis Y.

[0071] With reference to [Fig.9], the first frame 3 comprises a central connection portion 34, connecting the right arm 31 and the left arm 32, in particular, along the lateral axis Y so as to make them integral with each other and allow transmission of forces. The first frame 3 also preferably comprises an upper connection portion 35 connecting the upper ends 3S of the two arms 31, 32, so as to reinforce the connection between the two arms 31, 32 of the first frame 3 and also allow transmission of forces. In this embodiment, a first single-piece frame 3 is described comprising two arms 31, 32, connected by a central connection portion 34 and an upper connection portion 35. It goes without saying that the first frame 3 could be produced by assembly or be formed directly from a single piece.

[0072] With reference to [Fig. 10], the second frame 4 of the elevation system 1 according to the invention comprises a lower end 41 pivotally mounted in the support base 2 and an upper end 4S connected to the pilot seat S. Preferably, the lower end 41 is connected to the rear portion 26 of the support base 2 via the connecting member 5 and the upper end 4S is connected to the front of the seat base S (as shown in [Fig. 5]).

[0073] In one embodiment, still with reference to [Fig. 10], the second frame 4 comprises a right arm 41 and a left arm 42. The right arm 41 and the left arm 42 are preferably distinct. Also, in this example, each arm 41, 42 of the second frame 4 comprises a lower end 411, 412. With reference to [Fig. 11], the lower end 411, 412 of each arm 41, 42 of the second frame 4 preferably comprises a third through-orifice 03, along the lateral axis Y, in order to cooperate with the connecting member 5, as will be described later.

[0074] Preferably, the right arm 41 and the left arm 42 are symmetrical. Also, only the right arm 41 will be described subsequently.

[0075] In a preferred embodiment, with reference to [Fig. 12] showing the second frame 4 flat in a plane (Y, Z), the right arm 41 comprises successively from the top to the bottom along the vertical axis Z, an upper portion 43, a intermediate portion 44 and a lower portion 45. The lower 45 and upper 43 portions extend longitudinally along the Z axis. The intermediate portion 44 connects the upper portion 43 and the lower portion 45 and preferably forms an angle of inclination a with the vertical axis Z. The angle of inclination a is preferably between 10° and 40° and gives the second frame 4 formed by the two symmetrical arms 41, 42 a Y-shaped profile.

[0076] Preferably, the upper portions 43 of the two arms 41, 42 are spaced apart by a distance b (shown in [Fig. 12]) of at least 50 mm. Preferably, the distance b is between 50 mm and 200 mm.

[0077] Preferably, as shown in [Fig. 12], the lower portions 45 of the two arms 41, 42 are adjacent, preferably in contact, in order to form a single foot.

[0078] In this example, similarly to the first frame 3, the upper end 4S of each arm 41, 42 of the second frame 4 is connected to the pilot seat S, preferably by pivot connections, so as to allow pivoting between the second frame 4 and the seat S around the lateral axis Y. For this, the upper end 4S of each arm 41, 42 of the second frame 4 comprises a fourth through-hole 04 (shown in [Fig. 11]), along the lateral axis Y, allowing the passage of a second crosspiece (not shown), connecting the second frame 4 and the seat base S. Such a crosspiece allows a pivot connection while allowing the lateral sliding of the crosspiece in the fourth holes 04 of the upper ends 4S of the arms 41, 42 of the second frame 4, making it possible to adjust the lateral position of the seat S along the Y axis.

[0079] As described above, the first frame 3 and the second frame 4 are articulated together. For this, the elevation system 1 comprises a first pivot axis 6 (shown in [Fig.7]), mechanically connecting the first arm 31 of the first frame 3 and the first arm 41 of the second frame 4 and a second pivot axis 6, mechanically connecting the second arm 32 of the first frame 3 and the second arm 42 of the second frame 4. Preferably, the first frame 3 and the second frame 4 are connected substantially by the middle of each arm 31, 32, 41, 42, so as to form a crosspiece. Thanks to the articulation between the first frame 3 and the second frame 4, the elevation system 1 makes it possible to modify the height of the pilot seat S along the vertical axis Z.

[0080] With reference to [Fig. 10], as described previously, the elevation system 1 according to the invention comprises a connecting member 5 connecting the right lateral part 21 and the left lateral part 22 of the support base 2. Preferably, the elevation system 1 comprises a single connecting member 5 for connecting the right lateral part 21 and the left lateral part 22. The connecting member 5 also makes it possible to connect the support base 2 and the second frame 4.

[0081] The connecting member 5 is in this example in the form of a tube extending along the lateral axis Y at the rear portion 25 of the support base 2 between the right lateral portion 21 and the left lateral portion 22, the connecting member 5 being fixed to the right lateral portion 21 and the left lateral portion 22 of the support base 2. In this example, the connecting member 5 is inserted into the first through-holes 01 of the rear portion 25 of the support base 2, so as to connect them mechanically. The connecting member 5 preferably has a circular section so as to allow a pivot connection with the second frame 4.

[0082] According to the invention, the connecting member 5 is connected to the lower end 41 of each arm 41, 42 of the second frame 4, as shown in [Fig. 10]. For this, the connecting member 5 is preferably inserted, by sliding, into the third through-orifice 03 of the lower end 411, 412 of each arm 41, 42 of the second frame 4.

[0083] The lower end 411, 412 of each arm 41, 42 of the second frame 4 is configured to pivot around the connecting member 5, making it possible to release rotation around the lateral axis Y of the second frame 4 relative to the connecting member 5 and therefore relative to the support base 2. Such a connection makes it possible to release a degree of freedom and thus to limit the transmission of forces between the second frame 4 and the support base 2, making it possible to limit the stresses in the parts of the elevation system 1.

[0084] Preferably, the right arm 41 and the left arm 42 of the second frame 4 are connected to the connecting member 5 in the same central zone Q0, shown in [Fig. 10]. In other words, the single foot of the second frame 4 is connected to the connecting member 5. Preferably, the central zone Q0 of the connecting member 5 is equidistant from the right lateral part 21 and the left lateral part 22 of the support base 2. In other words, the central zone Q0 is centered on the connecting member 5 between the two lateral parts 21, 22 of the support base 2.

[0085] In practice, as shown in Figures 10 and 11, the single foot is connected to the connecting member 5 at a third connecting point P3.

[0086] Thanks to the single foot and the third connection P3, the assembly formed by the first frame 3 and the second frame 4 is connected at four points to the seat base S, via the upper ends 3S, 4S and at three points with the support base 2 (via the connecting member 5). In other words, the connection between the first frame 3 and the second frame 4 and the support base 2 is isostatic, which is particularly advantageous for limiting over-stresses in the elevation system 1. Indeed, in the prior art elevation system 1, the first frame 3 and the second frame 4 were connected to the support base 2 at four points distributed substantially at the four corners of the base of support 2, which made the connection hyperstatic and generated additional stresses in the parts and greater forces in the fixings. Thanks to the second frame 4 according to the invention and to the connecting member 5, the elevation system 1 is no longer over-stressed and it is no longer necessary to reinforce it more significantly.

[0087] An example of implementation of the deformation of the elevation system 1 according to the invention will be presented during a qualification test. During such a test, the seat S is subjected to significant acceleration under particular conditions of twisting of the floor P, therefore of the longitudinal rails RI, R2, the twisting of the floor P causing a twisting of the support base 2. Such deformation is known to those skilled in the art under the designation “pitch and roll”.

[0088] The method is described in the case of a pilot seat S mounted on two longitudinal rails RI, R2, by means of a lifting system 1 according to the invention, as described previously.

[0089] The method comprises a first step of deforming the first longitudinal rail RI and the second longitudinal rail R2. The first longitudinal rail RI is subjected to twisting around the longitudinal axis X and the second longitudinal rail R2 to twisting around the lateral axis Y, causing twisting of the lateral parts 21, 22 of the support base 2 to which the longitudinal rails RI, R2 are respectively connected. The twisting causes torsion of the support base 2. The H-shape of the support base 2 allows it to deform easily while limiting both the forces transmitted to the two frames 3, 4 and the stresses in the support base 2.

[0090] During this deformation, the forces transmitted from the support base 2 to the frames 3, 4 are also limited due to the connecting member 5.

[0091] Indeed, the connecting member 5 makes it possible to mechanically connect the support base 2 and each arm 41, 42 of the second frame 4 indirectly, unlike the elevation system 1 of the prior art, in which the second frame 4 was connected directly to each lateral part 21, 22 of the support base 2. The connecting member 5 makes it possible to absorb part of the forces which pass through the longitudinal rails RI, R2 and therefore through each lateral part 21, 22 of the support base 2, during the deformation of the rails RI, R2 and therefore the twisting of the support base 2 as described previously.

[0092] More precisely, thanks to the connecting member 5 which allows the rotation of the lower end 41 of the second frame 4 around the lateral axis Y, part of the forces resulting from the deformation of the longitudinal rails RI, R2 are not transmitted to the frames 3, 4. Thus, less forces pass through the parts and the fixings of the elevation system 1.

[0093] The method then preferably comprises a step of application to the whole formed by the longitudinal rails RI, R2, the pilot seat S and the elevation system 1 of a first acceleration of 16G dynamic in a direction substantially +X corresponding to the acceleration seen during a crash case.

[0094] Thanks to the elevation system 1 according to the invention and in particular to the connection between the two frames 3, 4 and the support base 2 at three points, isostatic, the forces which pass through the elevation system 1 and through the longitudinal rails RI, R2 are significantly limited before the application of the accelerations. The dynamic acceleration 16G in a direction substantially +X, corresponding to a crash case, projects the pilot in his seat forward, causing the appearance of significant forces. Thanks to the elevation system according to the invention, a significant quantity of the forces generated by the acceleration of the crash case is not transmitted from the seat to the support base 2. Also, less forces pass through the fixings between the elevation system 1 and the longitudinal rails RI, R2.

[0095] The elevation system according to the invention makes it possible to adjust the position of the pilot's seat along the longitudinal axis X, the lateral axis Y and the vertical axis Z, so as to precisely position the pilot's eye and allow him to have an optimal field of vision for piloting the aircraft. The connecting member between the support base and the second frame also allows an isostatic connection between the two frames and the support base, which very significantly limits over-stresses in each part of the elevation system, in particular during a crash test. Thanks to the elevation system according to the invention, less force is transmitted to the frames and their fixings, even in the event of significant deformations of the aircraft floor and therefore of the longitudinal rails to which the support base is connected. The mass of the elevation system is also limited, which is important in an aeronautical context.

Claims

Claims

1. Elevation system (1) for an aircraft seat (S), the aircraft comprising a floor (P) and two longitudinal rails (RI, R2) extending along a longitudinal axis (X), the two longitudinal rails (RI, R2) being fixed to the floor (P), the elevation system (1) being configured to adjust the position of the seat (S) relative to the floor (P) of the aircraft, the elevation system (1) comprising: • a support base (2) configured to be mechanically connected to the longitudinal rails (RI, R2), the support base (2) comprising a right lateral part (21) and a left lateral part (22), the support base (2) being configured to slide along the longitudinal rails (RI, R2), so as to move the seat (S) along the longitudinal axis (X), • a first frame (3) comprising a lower end (31) pivotally and slidably mounted in the support base (2) and an upper end (3S) configured to be connected to the seat (S), • a second frame (4) comprising a lower end (41) pivotally mounted with the support base (2) and an upper end (4S) configured to be connected to the seat (S), the first frame (3) and the second frame (4) being articulated around a lateral axis (Y) so as to pivot relative to each other, the second frame (4) comprising a right arm (41) and a left arm (42), • the elevation system (1) being characterized in that it comprises a connecting member (5) connecting the right lateral part (21) and the left lateral part (22) of the support base (2), • each arm (41, 42) of the second frame (4) comprising a lower end (41), the lower ends of the arms (41, 42) are connected directly to the connecting member (5), the right arm (41) and the left arm (42) being connected to the connecting member (5) in the same central zone (QO) of the connecting member (5).

2. An elevation system (1) according to claim 1, wherein the area central part (Q0) of the connecting member (5) is equidistant from the lateral parts (21, 22) of the support base (2).

3. Lifting system (1) according to one of claims 1 to 2, wherein the lower end (41) of the right arm (41) and the lower end of the left arm (42) are adjacent.

4. Lifting system (1) according to one of claims 1 to 3, wherein the connecting member (5) is in the form of a transverse tube extending between the right lateral part (21) and the left lateral part (22) of the support base (2).

5. Lifting system (1) according to one of claims 1 to 4, comprising a single connecting member (5) connecting the right lateral part (21) and the left lateral part (22) of the support base (2), the lower end (41) of each arm (41, 42) of the second frame (4) is connected directly to the single connecting member (5).

6. Lifting system (1) according to one of claims 1 to 5, in which the second frame (4) is connected to the connecting member (5) by a sliding pivot connection.

7. Elevation system (1) according to one of claims 1 to 6, in which each arm (41, 42) of the second frame (4) comprises at least one upper portion (43) and one intermediate portion (44), the arms (41, 42) extending in the same plane, the intermediate portion (44) and the upper portion (43) form in said plane an angle of inclination (a) strictly greater than 0°.

8. An elevation system (1) according to claim 7, wherein the angle of inclination (a) is between 10 and 40°.

9. Set of two longitudinal rails (RI, R2), configured to be fixed to a floor (P) of an aircraft, and of a lifting system (1) according to one of claims 1 to 8, the support base (2) of the lifting system (1) being mechanically connected to the longitudinal rails (RI, R2).

10. Set of two longitudinal rails (RI, R2), configured to be fixed to a floor (P) of an aircraft, a seat (S) and a lifting system (1) according to one of claims 1 to 8, the support base (2) of the lifting system (1) being connected to the longitudinal rails (RI, R2) and the upper end (3S) of the first frame (3) and the upper end (4S) of the second frame (4) being mechanically connected to the seat (S).

11. Aircraft comprising a floor (P) and a set of two longitudinal rails longitudinal rails (RI, R2), a seat (S) and a lifting system (1) according to claim 10, the two longitudinal rails (RI, R2) being fixed to the floor (P).

12. Method for deforming a set of two longitudinal rails (RI, R2) and an elevation system (1) according to claim 10, the support base (2) of the elevation system (1) being mechanically connected to the longitudinal rails (RI, R2), the method comprising a step of deforming a first longitudinal rail (RI) along a first deformation axis and a second longitudinal rail (R2) along a second deformation axis, orthogonal to the first deformation axis.

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