Seating surface with kinetic energy absorbing tubes for seats, in particular aircraft seats

Abstract

The invention relates to a seat pan comprising a seat pan structure (11) comprising: - a first longitudinal member (12.1) having a front end portion (13.1) and a rear end portion (14.1); - a second longitudinal member (12.2) having a front end portion (13.2) and a rear end portion (14.2); - a front cross member (15.1) mechanically interconnecting the front end portion (13.1) of the first longitudinal member (12.1) and the front end portion (13.2) of the second longitudinal member (12.2); and - a rear cross member (15.2) mechanically interconnecting the rear end portion (14.1) of the first longitudinal member (12.1) and the rear end portion (14.2) of the second longitudinal member (12.2); the seat pan structure (11) further comprising a kinetic energy absorption tube (27) extending between the first longitudinal member (12.1) and the second longitudinal member (12.2).

Description

Technical Field

[0001] This invention relates to a seating surface provided with kinetic energy absorption tubes. The invention is particularly advantageous, but not exclusively applicable, to all types of aircraft seats of the "economy class," "business class," and "first class" or "pilot" class, as well as helicopter seats or seats in any other flight machinery. Background Technology

[0002] The seat is certified using methods known per se to examine its mechanical behavior during a crash. In a dynamic test known as the “14G down”, a dummy mounted in the seat undergoes a vertical deceleration of 14G. The test is validated if the lumbar load experienced by the dummy is less than a threshold S, such as 1500 lbf (i.e., 6672 N).

[0003] Figure 1a The standard seating surface 1 of the seat shown includes a seating surface structure 2 and a seating surface plate 3 for covering the seating surface structure 2. Figure 1b The seating surface structure 2 shown separately includes two longitudinal members 4.1 and 4.2 that are parallel to each other. These longitudinal members 4.1 and 4.2 are mechanically connected to each other by crossbars 5.1 and 5.2.

[0004] like Figure 2a As shown, Figure 2a The diagram shows the observable change in lumbar load over time during the "14G deceleration" test, using a so-called "HII type" dummy. This type of dummy, with a seat surface of approximately 1, easily passed the certification test. This HII type dummy, with a height of approximately 90 cm and a mass of approximately 74 kg in the seated position, was the certification standard at the time.

[0005] As demographics evolved, the certification rules were revised, and the HIII type dummy, which is heavier than the HII type, was used. In fact, the HIII type dummy has a height of approximately 87 cm and a mass of approximately 78 kg in the seated position. However, this change in dummy size affected the dynamic behavior of the seat during the "14G deceleration" test, causing the dummy to experience lumbar loads exceeding the permissible load threshold of 1500 lbf. Figure 2b As shown, the difference in lumbar load experienced by the HII and HIII dummies is on the order of 300 lbf.

[0006] After a detailed analysis of this phenomenon, the inventors proved that the increase in lumbar load was primarily due to the fact that the pelvis of the HIII dummy was wider than that of the HII dummy, and that it came into contact with the longitudinal members of the seating surface during the test. Summary of the Invention

[0007] The object of the present invention is, in particular, to effectively overcome the aforementioned disadvantages by providing a seating surface comprising a seating surface structure, the seating surface structure comprising:

[0008] - The first longitudinal member, including the front and rear sections.

[0009] - A second longitudinal member comprising a front end and a rear end.

[0010] - A front crossbar, which mechanically connects the front ends of the first longitudinal member and the front ends of the second longitudinal member to each other, and

[0011] - A rear crossbar that mechanically connects the rear end portions of the first longitudinal member and the rear end portions of the second longitudinal member to each other.

[0012] The seating surface structure also includes a kinetic energy absorption tube extending between the first longitudinal member and the second longitudinal member.

[0013] The present invention is thus certified by providing a kinetic energy absorption tube integrated into the seating surface, thereby reducing the lumbar load experienced by the dummy during the “14G deceleration” test.

[0014] According to one embodiment of the present invention, a first end of the kinetic energy absorption tube is mechanically connected to the first longitudinal member, and a second end of the kinetic energy absorption tube is mechanically connected to the second longitudinal member.

[0015] According to one embodiment of the present invention, the kinetic energy absorption tube is arranged in the upper part of the rear end portion of the longitudinal member.

[0016] According to one embodiment of the present invention, the kinetic energy absorption tube is a hollow tube made of a metallic material such as steel or aluminum.

[0017] According to one embodiment of the present invention, the kinetic energy absorption tube includes a plurality of grooves.

[0018] According to one embodiment of the invention, each longitudinal member further includes a distal portion extending between the respective front end portion and rear end portion, wherein the distance between the first longitudinal member and the second longitudinal member measured between the distal portions is greater than the distance between the first longitudinal member and the second longitudinal member measured between the front end portions, and / or the distance between the first longitudinal member and the second longitudinal member measured between the rear end portions.

[0019] According to one embodiment of the invention, the platform is mechanically connected to a corresponding distal portion.

[0020] According to one embodiment of the present invention, the seating surface further includes a seating surface plate that at least partially covers the seating surface area defined by the first longitudinal member and the second longitudinal member and by the front crossbar and the rear crossbar.

[0021] According to one embodiment of the invention, the seating surface plate includes at least one latching device for engaging with a crossbar.

[0022] According to one embodiment of the present invention, the seating surface plate carries at least one stop member, the stop member being used to withstand a crossbar when the seating surface is subjected to a vertical impact.

[0023] The present invention also relates to a seat comprising the seating surface as described above. Attached Figure Description

[0024] The invention will be better understood by reading the following detailed description, which includes embodiments given illustratively with reference to the accompanying drawings, presented by way of non-limiting example, which can be used to complete the understanding of the invention and its implementation, and, if necessary, help to define it, in which:

[0025] [ Figure 1a ] Figure 1a It is a perspective view of the aircraft seating surface as described in the prior art;

[0026] [ Figure 1b ] Figure 1b It is a perspective view of the aircraft seating surface structure for a seat according to the prior art, as already described;

[0027] [ Figure 2a ] Figure 2a It is already described in the context of including Figure 1a A graph showing the change in lumbar load over time observed on a HII-type dummy in a seat on the seating surface during a “14G deceleration” test.

[0028] [ Figure 2b ] Figure 2b It is already described in the context of including Figure 1a A graph showing the change in lumbar load over time observed on an HIII-type dummy in a seat on the seating surface during a “14G deceleration” test.

[0029] [ Figure 3a ][ Figure 3b ] Figure 3a and 3b These are perspective views taken from above and below the aircraft seating surface according to the present invention;

[0030] [ Figure 4a ][ Figure 4b ][ Figure 4c ] Figure 4a , 4b 4c shows a perspective view, a top view, and a side view of the aircraft seating surface structure according to the present invention;

[0031] [ Figure 5 ] Figure 5 This is a graph showing the maximum waist load observable during the "14G deceleration" test using the HIII-type dummy as a function of the indentation length at the distal portion of each longitudinal member.

[0032] [ Figure 6 ] Figure 6 This is a perspective view of an aircraft seat including a seating surface according to the present invention;

[0033] [ Figure 7 ] Figure 7 The modeling of the "seat-dummy" system using a "mass spring" type system is shown in the context of a "14G deceleration" test.

[0034] [ Figure 8 ] Figure 8 This is a diagram illustrating the change of lumbar load over time during a “14G deceleration” test on an HIII type dummy in a seat with an integrated kinetic energy absorption tube and an HIII type dummy in a seat without a kinetic energy absorption tube, according to the present invention.

[0035] [ Figure 9 ] Figure 9 It is a force curve that is a function of the deformation level of the kinetic energy absorption tube integrated into the seating surface according to the present invention;

[0036] [ Figure 10 ] Figure 10 It is the energy absorption curve as a function of the deformation level of the kinetic energy absorption tube integrated into the seating surface according to the present invention. Detailed Implementation

[0037] It should be noted that, in Figure 3a , 3b As shown in the following figures, structural and / or functional elements common to different embodiments have the same reference numerals. Therefore, unless otherwise stated, these elements have the same structure, dimensions, and material properties.

[0038] Furthermore, in the remainder of the specification, relative terms such as "front," "rear," "horizontal," and "vertical" are understood by reference to their common meaning in a seat comprising a seating surface according to the invention. Specifically, the "rear" element of the seating surface is located on one side of the backrest, while the "front" element is located on the side opposite the backrest. The front-rear orientation of the seating surface corresponds to... Figure 3a and 3b The left-right orientation in the middle.

[0039] We also define the axial direction X, which is parallel to the seating surface of the longitudinal member, the transverse direction Y, which is located in the horizontal plane and perpendicular to the direction X, and the vertical direction, which is perpendicular to the plane formed by the axes X and Y.

[0040] Figure 3a and 3b The aircraft seating surface 10 is shown, which includes a seating surface structure 11 and a seating surface plate 16 for covering the seating surface structure 11.

[0041] More accurately, such as Figures 4a to 4c As shown, the seating surface structure 11 includes a first longitudinal member 12.1 and a second longitudinal member 12.2. The first longitudinal member 12.1 includes a front end portion 13.1 and a rear end portion 14.1. The second longitudinal member 12.2 includes a front end portion 13.2 and a rear end portion 14.2.

[0042] The front crossbar 15.1 mechanically connects the front end portion 13.1 of the first longitudinal member 12.1 and the front end portion 13.2 of the second longitudinal member 12.2 to each other. The rear crossbar 15.2 mechanically connects the rear end portion 14.1 of the first longitudinal member 12.1 and the rear end portion 14.2 of the second longitudinal member 12.2 to each other.

[0043] The mechanical connection between the longitudinal members 12.1, 12.2 and the crossbars 15.1, 15.2 can be achieved by pins, rivets, screws, or any other suitable fastening device. In the example shown, the crossbars 15.1, 15.2 pass through correspondingly shaped holes 17 formed in the end portions of the longitudinal members 12.1, 12.2. To prevent the crossbars 15.1, 15.2 from translating relative to the longitudinal members 12.2, 12.2, pins 18 are inserted at each end of the crossbars 15.1, 15.2. The pins 18 advantageously extend in a plane perpendicular to the longitudinal extension direction of the crossbars 15.1, 15.2. The pins 18 are advantageously of a resilient type.

[0044] Furthermore, the longitudinal members 12.1 and 12.2 include a fixing interface 20 on one side of the rear portions 14.1 and 14.2, which interacts with the seat back. The fixing interface 20 may include a hole between two perforated arms of a cover of the backrest structure. The connection of this component can be secured, for example, by a screw with a shoulder that engages with a corresponding nut or an internal thread in a hole in one arm of the cover of the backrest structure (not shown).

[0045] The longitudinal members 12.1 and 12.2 include a fixing interface 21 on one side of the front end portions 13.1 and 13.2, which interacts with elements (particularly brackets) of the seating surface structure. The fixing interface 21 may include a channel hole for a rod that forms an axis of rotation of the seating surface 10 relative to the seating surface structure.

[0046] Advantageously, such as in Figure 4a and 4b As can be clearly seen, each longitudinal member 12.1, 12.2 further includes a distal portion 23.1, 23.2 extending between the corresponding front end portion 13.1, 13.2 and the rear end portion 14.1, 14.2. Therefore, longitudinal member 12.1 includes a distal portion 23.1 extending between the front end portion 13.1 and the rear end portion 14.1. Longitudinal member 12.2 includes a distal portion 23.2 extending between the front end portion 13.2 and the rear end portion 14.2.

[0047] The distance L1 between the first longitudinal member 12.1 and the second longitudinal member 12.2, measured between the distal portions 23.1 and 23.2, is greater than the distance L2 between the first longitudinal member 12.1 and the second longitudinal member 12.2, measured between the front portions 13.1 and 13.2, and / or the distance L3 between the first longitudinal member 12.1 and the second longitudinal member 12.2, measured between the rear portions 14.1 and 14.2. In this case, distance L1 is greater than distance L2. Distance L1 is also greater than distance L3. Each distal portion 23.1 and 23.2 extends over at least 20% of the total length of the corresponding longitudinal member 12.1 and 12.2. Distance L2 or L3 is, for example, on the order of 36 cm.

[0048] Figure 5 The variation of the waist load is shown as a function of the variation of the recess length L4 of the distal portions 23.1, 23.2 of each longitudinal member 12.1, 12.2 relative to the inner edge of the front end portion 13 (see [reference]). Figure 4bThe figure highlights that the greater the indentation length L4, the greater the reduction in lumbar load experienced by the dummy. In fact, the spacing between the two longitudinal members 12.1 and 12.2 allows the pelvis to pass between them. Curve C1 was obtained without any adjustment to the stiffness of the seating surface 10, and curve C2, shown as a dashed line, was obtained by adjusting the stiffness of the seating surface through the integration of the kinetic energy-absorbing tubes, which are described in more detail below.

[0049] Alternatively, the distance between L2 and L3 may be equal to the distance between L1, especially when the distal portions 23.1 and 23.2 are located in the extension of the front portions 13.1 and 13.2 or the rear portions 14.1 and 14.2.

[0050] The distal portions 23.1, 23.2 are connected via connecting portion 24 to the corresponding end portions 13.1, 13.2 or 14.1, 14.2 of the longitudinal member, such as... Figure 4a and 4b As shown. In the example shown, the connecting portion 24 has a circular shape with inflection points corresponding to changes in the direction of curvature. Therefore, the connecting portion 24 typically has a flat S-shape. Alternatively, the connecting portion 24 may have a ramp shape forming an angle of approximately 45 degrees with respect to the ends.

[0051] The distal portions 23.1, 23.2 of the first longitudinal member 12.1 and the second longitudinal member 12.2 have a straight shape. Alternatively, the distal portions 23.1, 23.2 may have an arc shape or any other shape, which can create an increased distance between the two longitudinal members 12.1, 12.2.

[0052] Furthermore, platform 25 is mechanically connected to the corresponding distal portions 23.1, 23.2. Platform 25 extends in the longitudinal extensions of the front portions 13.1, 13.2 and rear portions 14.1, 14.2 of the corresponding longitudinal members 12.1, 12.2. Platform 25 is located in the clearance space defined by the distal portions 23.1, 23.2 and the connecting portion 24 located at each end of the distal portions 23.1, 23.2. Platform 25 forms the support area of ​​the seat surface reinforcement, which will be described in more detail below. Platform 25 has a reduced thickness compared to the longitudinal members 12.1, 12.2.

[0053] Advantageously, the longitudinal members 12.1, 12.2 and the crossbars 15.1, 15.2 are made of a metallic material. According to an exemplary embodiment, the longitudinal members 12.1, 12.2 may be made of aluminum, while the crossbars 15.1, 15.2 take the form of tubes made of steel. Alternatively, the longitudinal members 12.1, 12.2 and the crossbars 15.1, 15.2 may be made of the same metallic material. Alternatively, the longitudinal members 12.1, 12.2 and the crossbars 15.1, 15.2 may be made of materials other than metal, such as fiber-loaded composite materials, or any other material suitable for the application.

[0054] In addition, such as Figure 3b and 4a As shown, the kinetic energy absorption tube 27 extends between the first longitudinal member 12.1 and the second longitudinal member 12.2. The first end of the tube 27 is mechanically connected to the first longitudinal member 12.1, and the second end of the tube 27 is mechanically connected to the second longitudinal member 12.2.

[0055] The end of tube 27 is preferably connected to the rear end portions 14.1, 14.2 of the first longitudinal member 12.1 and the second longitudinal member 12.2. For the connection between the crossbars 15.1, 15.2 and the longitudinal members 12.1, 12.2, the mechanical connection between tube 27 and the longitudinal members 12.1, 12.2 can be achieved by a pin 18, which passes directly through and is inserted into a receiving hole 28 provided in the longitudinal members 12.1, 12.2. The pin 18 extends in a plane perpendicular to the longitudinal extension direction of tube 27. Alternatively, the mechanical connection can be formed by screws, rivets, welding, or any other fastening device suitable for the application.

[0056] The purpose of tube 27 is to absorb at least a portion of the dummy's kinetic energy through mechanical deformation during the "14G deceleration" test.

[0057] Advantageously, tube 27 is made of a metallic material, such as steel or aluminum. Tube 27 is a hollow tube, and its thickness can be adjusted according to the required rigidity. The thickness of tube 27 is specifically adjusted according to the material selected.

[0058] According to an exemplary embodiment, tube 27 is a steel tube having a thickness of approximately 2 mm and a diameter of approximately 14 mm. "Approximately" means that it may vary by 10% relative to the stated value. Here, tube 27 has a circular cross-section, but it may also have a square, rectangular, triangular, elliptical, or any other geometric shape suitable for the application.

[0059] Advantageously, such as Figure 4cAs shown, tube 27 is arranged in the upper part of the rear portions 14.1, 14.2, that is, tube 27 is preferably arranged above the intermediate horizontal plane Pm of the longitudinal members 12.1, 12.2. This allows it to reduce the initial distance that separates the dummy's pelvis from the tube 27 of the first rigid element of the seating surface 10 in the force path. This reduces the velocity of the pelvis during deceleration and thus reduces the kinetic energy to be dissipated.

[0060] The kinetic energy absorption tube 27 can also deflect the dummy's pelvis from its vertical trajectory during the "14G deceleration" test by generating a velocity component along the X-axis. This reduces the energy absorbed through the tube 27 in the vertical Z direction.

[0061] according to Figure 4b In the specific embodiment shown, the kinetic energy absorbing tube 27 may include a plurality of grooves 30. The grooves 30 are formed in a direction perpendicular to the axis of the tube 27. This configuration allows it to mechanically weaken the tube 27, thereby allowing for greater deformation of the tube 27.

[0062] like Figure 3a and 3b As shown, the seating surface plate 16 at least partially covers the seating surface area defined by the first longitudinal member 12.1 and the second longitudinal member 12.2, as well as by the front crossbar 15.1 and the rear crossbar member 15.2. The seating surface plate 16 includes a top surface 16.1 and a bottom surface 16.2 opposite to the top surface, on which the seating surface pad can be pressed. The seating surface plate 16 is made of a metal material with a thickness between 0.5 mm and 1.5 mm, preferably about 0.8 mm.

[0063] The seating surface plate 16 carries at least one reinforcing member 33 extending in a direction parallel to the crossbars 15.1 and 15.2. The reinforcing member 33 preferably extends over the entire width of the seating surface plate 16. The reinforcing member 33 may be formed from a metal sheet folded into a U-shape or an Ω-shape. In this case, the seating surface plate 16 includes three reinforcing members 33 respectively arranged in the front, rear, and middle portions of the seating surface plate 16. The reinforcing members 33 are fixed to the top of the seating surface 10 by fixing bolts 34.

[0064] The intermediate reinforcement 33 includes end portions, each abutting against a corresponding platform 25. The length of the intermediate reinforcement 33 is substantially equal to the distance L1. The platform 25 may include holes 35 for the passage of fixing bolts 34 of the intermediate reinforcement 33, such as... Figure 3b As shown.

[0065] To allow easy removal of the seating surface panel 16 to access the kinematic components arranged beneath the seat, the seating surface panel 16 includes at least one (two in this illustration) latching device 37 for engaging with the front crossbar 15.1 and the rear crossbar 15.2 of the seat, respectively. For this purpose, each latching device 37 includes two resiliently deformable protrusions 38 that define recesses 39 for receiving the corresponding crossbars 15.1, 15.2. The protrusions 38 may have a bevel at each free end to facilitate crossbar insertion. The protrusions 38 thus have an Ω shape (Ω). Hinges may also be integrated to facilitate movement of the seating surface panel 16 relative to the seating surface structure 11.

[0066] like Figure 3b As shown, the seating surface 16 also carries at least one stop 41 for bearing against the crossbar when the seating surface 10 is subjected to a vertical impact. The stop 41 is fixed to the lower surface 16.2 of the seating surface 10. The purpose of the stop 41 is to retain the seating surface 16 to prevent its vertical collapse during the impact. In the example shown, the seating surface 10 includes two stops 41 for bearing against the rear crossbar 15.2 during the downward movement of the seating surface 16 under a vertical impact.

[0067] The stop 41 may have an L-shape facing the rear crossbar 15.2. Therefore, when the seat surface plate 16 moves downward, the folded end of the L-shape can abut against the rear crossbar 15.2. When the seat surface plate 16 is not deformed, the stop 41 is located at a certain distance from the crossbar 15.2. As the seat surface plate 16 deforms downward, the stop 41 will abut against the crossbar 15.2.

[0068] Figure 6 An aircraft seat 42 is shown, comprising a seating surface 10 and a backrest 43 according to the invention. The seating surface 10 is mounted on a bracket 44 associated with a lower structure 45, which is provided with a lock 46 that allows the seat 42 to be secured to a track in the aircraft cabin.

[0069] The seat 42 is advantageously provided with a kinematic component 47 supported by a lower structure 45 of the seat 42. The kinematic component 47 allows movement of the seating surface 10 and backrest 43 of the seat 42 between a "seated" position and a "reclining" position. In the "seated" position, the seat 42 is configured to define a seating position for the passenger, and in the "reclining" position, the seat 42 is configured to define a sleeping surface for the passenger, advantageously being substantially horizontal. Intermediate comfort positions are also provided, such as a "relaxed" position with the backrest 43 reclined significantly.

[0070] In order to predict the dynamic behavior of seat 42 during the "14G deceleration" test, Figure 7The “seat 42-dummy 49” system shown is modeled as a “mass spring” type system. Therefore, we assume that component 51, formed by the head and shoulders of the HIII-type dummy 49, has a mass of approximately 35 kg, and the pelvis 52 has a mass of approximately 12 kg and a predetermined stiffness K1 of approximately 300 N / mm. The seating surface pad 53 has a stiffness K2 of approximately 100 N / mm, while the seating surface 10 has a stiffness K3 to be optimized. The lower structure 45 has a stiffness K4 of approximately 600 N / mm. The floor of the aircraft 54, on which the seat 42 is mounted via fixed rails, can be considered to have infinite stiffness. The lumbar load is measured by a sensor 55 placed at the level of the spine above the pelvis of the dummy 49. The force F experienced is equal to the product of the mass M and the deceleration a.

[0071] By changing the configuration (material and size) of the kinetic energy absorption tube 27, the coefficient K3 of the seating surface 10 can be adjusted to minimize the lumbar load experienced by the dummy 49 during the test.

[0072] For the aforementioned tube 27, which is made of steel and has a thickness of 2 mm and a diameter of 14 mm, Figure 8 It is emphasized that the lumbar load observed during the “14G deceleration” test is far below the limit threshold S of 1500 (see curve C3, which shows a peak at 1452 lbs), while for the standard seat 42 without kinetic energy absorption tubes 27 on the seat surface 10, the lumbar load is far above the limit threshold S (see curve C4).

[0073] Figure 9 The force curve shown as a function of the displacement of the kinetic energy absorption tube 27 highlights the fitting stiffness K3 of approximately 313 N / mm. Figure 10 The energy curve shown corresponds to Figure 9 The curve is the integral of the displacement. The energy curve shows that tube 27 was able to absorb 66 joules during the “14G deceleration” test, which represents approximately 75% of the kinetic energy of dummy 49 during deceleration.

[0074] In some embodiments, a kinetic energy-absorbing tube 27 without a seating surface configuration 10 may be used, wherein the longitudinal members of the seating surface configuration 10 have locally enlarged intervals to allow the pelvis to pass through, that is, a seating surface 10 that integrates only the tube 27 without any distal portions 23.1, 23.2 is achieved.

[0075] In some embodiments, a seating surface 10 including distal portions 23.1, 23.2 may be provided to facilitate the passage of the dummy pelvis during the “14G deceleration” test, but without any kinetic energy absorption tubes 27.

[0076] Of course, different features, variations and / or embodiments of the present invention can be associated with each other in various combinations, as long as they are not incompatible or exclusive with each other.

[0077] Furthermore, the present invention is not limited to the embodiments described above, which are provided only as examples. The present invention includes various modifications, alternatives, and other variations that may be conceived by those skilled in the art within the context of the present invention, as well as, in particular, all combinations of the different operating modes described above, which may be employed individually or in combination.

Claims

1. A seating surface (10) including a seating surface structure (11), comprising: - A first longitudinal member (12.1) comprising a front end portion (13.1) and a rear end portion (14.1). - A second longitudinal member (12.2) including a front end portion (13.2) and a rear end portion (14.2). - A front crossbar (15.1) that mechanically connects the front end portion (13.1) of the first longitudinal member (12.1) and the front end portion (13.2) of the second longitudinal member (12.2) to each other, and - A rear crossbar (15.2) that mechanically connects the rear end portion (14.1) of the first longitudinal member (12.1) and the rear end portion (14.2) of the second longitudinal member (12.2) to each other. The seat surface structure (11) is characterized in that it further includes a kinetic energy absorption tube (27) extending between the first longitudinal member (12.1) and the second longitudinal member (12.2). The kinetic energy absorption tube (27) is arranged in the upper part of the rear end portion (14.1, 14.2) of the longitudinal members (12.1, 12.2) and above the middle horizontal plane (Pm) of the longitudinal members (12.1, 12.2).

2. The seating surface according to claim 1, characterized in that, The first end of the kinetic energy absorption tube (27) is mechanically connected to the first longitudinal member (12.1), and the second end of the kinetic energy absorption tube (27) is mechanically connected to the second longitudinal member (12.2).

3. The seating surface according to claim 1, characterized in that, The kinetic energy absorption tube (27) is a hollow tube made of metal material.

4. The seating surface according to claim 1, characterized in that, The kinetic energy absorption tube (27) includes multiple grooves (30).

5. The seating surface according to claim 1, characterized in that, Each longitudinal member (12.1, 12.2) also includes a distal portion (23.1, 23.2) extending between the respective front end portion (13.1, 13.2) and rear end portion (14.1, 14.2), wherein the distance (L1) between the first longitudinal member (12.1) and the second longitudinal member (12.2) measured between the distal portions (23.1, 23.2) is greater than the distance (L2) between the first longitudinal member (12.1) and the second longitudinal member (12.2) measured between the front end portions (13.1, 13.2), and / or the distance (L3) between the first longitudinal member (12.1) and the second longitudinal member (12.2) measured between the rear end portions (14.1, 14.2).

6. The seating surface according to claim 5, characterized in that, The platform (25) is mechanically connected to the corresponding distal portion (23.1, 23.2).

7. The seating surface according to any one of claims 1 to 6, characterized in that, The seating surface also includes a seating surface plate (16) that at least partially covers the seating surface area defined by the first longitudinal member (12.1) and the second longitudinal member (12.2), as well as the front crossbar (15.1) and the rear crossbar (15.2).

8. The seating surface according to claim 7, characterized in that, The seating surface plate (16) includes at least one latching device (37) for cooperating with the crossbars (15.1, 15.2).

9. The seating surface according to claim 7, characterized in that, The seating surface plate (16) carries at least one stop (41) for bearing against the crossbar when the seating surface (10) is subjected to a vertical impact.

10. A seat (42) comprising a seating surface (10) as described in any of the preceding claims.

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