Abstract:
The invention relates to a seat back for an aircraft comprising a structural column bearing a plurality of devices for supporting an occupant of the seat, these devices being distributed along the structural column and oriented transversely relatively to the structural column so as to each protrude on either side of this column. This solution can reduce the mass and dimensions, while providing satisfactory comfort for the occupant.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to the field of aircraft seats, particularly seats fitted in the passenger compartment of commercial aircraft, this compartment usually being called the aircraft “cabin”. 
         [0002]    The invention relates more particularly to an improvement to the design of the back of aircraft seats. 
       BACKGROUND 
       [0003]    In existing aircraft, seat backs have a structural part, for example in the form of a frame, onto which many elements such as cushions are added, designed to make the occupants of these seats more comfortable. For example, such a commercial aircraft seat is described in document US 2010/0308166. 
         [0004]    This design, although widespread, has a large mass and size, particularly due to the large volume of the structural part. The comfort of the occupant also has to be optimised. In this respect, in particular there is a need for a more uniform resistance to pressure applied by the occupant on the seat back. 
       SUMMARY 
       [0005]    Therefore, the purpose of the invention is to at least partially correct the disadvantages mentioned above applicable to embodiments according to prior art. 
         [0006]    To achieve this, the subject of the invention is firstly an aircraft seat back comprising a structural column with a plurality of seat occupant support devices, said support devices being distributed along the structural column and oriented transverse to the column so that they protrude from each side of this column. 
         [0007]    Furthermore, the attachment means comprise a plurality of segments capable of pivoting relative to each other, including a central segment mounted on the structural column so as to pivot relative to it, said support means also comprising two lateral segments mounted at the two opposite ends of the central segment, capable of pivoting relative to the central segment. Finally, each support device is sufficiently flexible so that it can deform elastically under the effect of the pressure of an occupant&#39;s back leaning on the seat back. 
         [0008]    The disclosed invention is a breakthrough from previous aeronautical designs, this breakthrough results particularly from the use of a column shaped structural part of the seat back, like a backbone. This design can reduce the mass and dimensions, the dimensions being reduced particularly on both sides of the structural column, advantageously resulting in space saving for the legs of the occupant behind this seat. 
         [0009]    Furthermore, the increased number of the occupant support devices contributes to improved comfort because each device added to the structural column can thus locally match the topology, namely the relief of the occupant&#39;s back. The result is a more uniform resistance of pressure applied by the occupant on the seat back. 
         [0010]    Furthermore, segmentation of comfort elements of the back, in other words support devices, helps to improve aeration and consequently limits risks of perspiration due to the local warm spots. This segmentation also reduces the global mass of the seat back. The above-mentioned advantages are even more significant when said support devices are at a spacing from each other along the structural column. In such a preferred configuration, spaces between support devices are left free and are therefore visible from outside the seat. Alternately, at least some of these spaces may be functionalised, for example by installing vibrating elements for providing a back massage. 
         [0011]    As mentioned above, the seat back comprises means of attachment of this device on the structural column associated with each support device. Therefore, the support devices can be replaced independently of each other, for cost saving. 
         [0012]    Furthermore, the increased number of segments helps to get a better match to local topology. With the proposed embodiment, each support device can deform in many ways depending on the force applied by the occupant, this deformation along the device possibly being in the shape of a curve, or even two inverted curves to result in an inflection point. In this case, each device is free to deform, accompanying the occupant&#39;s torsion movements. In particular this is possible due to at least one of the segments of the attachment means being sufficiently flexible to deform under the force applied by an occupant sitting in the seat. 
         [0013]    Preferably, each of the lateral segments is mounted on the associated support device through its two opposite ends, the two opposite ends of each lateral segment preferably being capable of pivoting about the support device. 
         [0014]    In this respect, note that pivot functions are preferably obtained by pivot connections or articulations, but other similar means may be adopted such as flexible links, for example elastomer links. Pivot pins forming part of these attachment means are preferably all approximately parallel. 
         [0015]    Preferably, the attachment means of each support device are usually convex towards the back, these means preferably being fixed between the column and the occupant support devices. Consequently, starting from the structural column and on both sides of it, the back extends laterally and forwards, which frees even more room for the legs of the occupant behind the seat. 
         [0016]    Preferably, all segments of attachment means of a support device are located approximately in the same plane, which is preferably approximately locally orthogonal to the structural column. Furthermore, segment pivot pins are also approximately orthogonal to this plane. 
         [0017]    Preferably, each support device is in the form of a transverse lath. Therefore this lath is capable of deforming elastically to match the pressure applied by the occupant&#39;s back. 
         [0018]    Preferably, each transverse lath comprises a foam portion, preferably surrounding a core of the lath. 
         [0019]    Preferably, the laths form the outside surface of the seat back with which the seat occupant will come into contact. A cover could also be provided over all these laths without going outside the scope of the invention. 
         [0020]    Very preferably for comfort reasons, each support device is sufficiently flexible so that it can deform elastically under the effect of the pressure applied by the back of an occupant leaning on the seat back. 
         [0021]    Finally, said support devices preferably do not have any direct contact with said structural column, because they are separated from it by said attachment means. Consequently, the occupant&#39;s back is at a distance from the structural column and comfort is improved. Spacing of the support devices also gives greater freedom of deformation, particularly during torsion movements of the back. 
         [0022]    Another purpose of the invention is an aircraft seat comprising a seat back as disclosed above. 
         [0023]    Another purpose is an aircraft comprising at least one such seat which is preferably a cabin seat for the passenger compartment of the aircraft. 
         [0024]    Other advantages and characteristics of the invention will become clear after reading the non-limitative detailed description given below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    This description will be made with reference to the appended drawings among which; 
           [0026]      FIG. 1  shows a perspective view of a part of a passenger compartment in a commercial aircraft, the compartment being fitted with cabin seats according to a preferred embodiment of the invention; 
           [0027]      FIG. 2  shows a side view of one of the seats shown in  FIG. 1 ; 
           [0028]      FIG. 3  shows an enlarged perspective view of a part of the back of the seat in  FIG. 2 ; 
           [0029]      FIG. 4  shows a top view of the seat shown in  FIGS. 2 and 3 ; 
           [0030]      FIG. 5  is a sectional view taken along plane P in  FIG. 3 ; and 
           [0031]      FIGS. 6   a  to  6   e  diagrammatically show a top view of one of the laths of the seat back according to different configurations as a function of the pressure applied by the occupant. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    With reference firstly to  FIG. 1 , the figure shows part of a passenger compartment  100  of a commercial aircraft fitted with cabin seats  1  according to this invention. The seats  1  are arranged conventionally in rows. 
         [0033]    Each seat  1  comprises a seat  2 , a seat back  4 , a headrest  6  and means  8  of fixing the seat onto the floor of the cabin compartment. The seat  2  and the headrest  6  have conventional shapes. 
         [0034]    The means  8  comprise stands  10  that will be connected to floor rails, and a transverse shaft  12  carried by the stands  10  and on which the seat  2  is hinged, so that the back can be rotated about the axis of this shaft. The back  4  is fixed to the shaft  12 . It comprises a structural column  14  extending approximately in the vertical direction from the shaft  12 , from a central zone of the shaft. These two elements can be added one onto the other or can be made from a single piece, preferably a metallic material or composite material. Another possibility would be to make the shaft  12  fixed to the seat  2  and to make the lower end of the column  14  hinged on this shaft  12 , so that the seat back can be rotated about the axis of the shaft  12 , relative to the seat. 
         [0035]    Globally, the seat back  4  comprises the structural column  14  to the end of which the headrest  6  is fitted, together with the occupant support devices  16 , and finally the means  20  of fastening these devices to the column  14  forming the frame of the seat back. The seat back  4  has a generally skeleton type shape, completely different from aircraft seats designed according to prior art. 
         [0036]    The section of the structural column  14  is closed, and for example may be square or rectangular, possibly with rounded edges. Nevertheless, other open sections may be envisaged, for example a U-shape. The column  14  is generally curved in shape, possibly double curved as shown in  FIG. 1 , to follow the shape of the back of the occupant sitting in the seat. 
         [0037]    The back  4  of the seat  1  will now be described in more detail with reference to  FIGS. 1 to 5 . 
         [0038]    Firstly, the general skeleton shape is obtained using support devices  16  arranged transverse to the column  14  on which they are mounted, protruding from each side of it, preferably symmetrically about the column. Each device  16  is preferably in the form of an elongated element extending transversely made with one or several nested bodies, and in this case resembling a lath. The section of this lath  16  may have different shapes, for example approximately square or approximately rectangular, and possibly with rounded edges. 
         [0039]    According to one example embodiment, the ratio between the length and the width of the flexible lath is between 5 and 20. The laths  16  are distributed along the column  14  but do not come into direct contact with it because the attachment means  20  are inserted between them. As can be seen in the above mentioned figures, the laths  16  in front of the column forming the rear part of the seat back, are at a spacing from each other along the column. They are parallel to each other and parallel to the lower edge of the headrest and the edge of the seat. 
         [0040]    The spaces between laths may extend over a height of between 0.3 and 3 times the height of the laths. These inter-lath spaces are preferably retained in the final state of the seat to help to aerate the seat back, and they can be seen from outside the seat unless a seat cover is provided to cover the assembly. Alternately, these spaces could include elements with different functions (not shown), for example vibrating elements for massaging the back of the occupant sitting in the seat  1 . 
         [0041]    As can be seen better in  FIG. 4 , attachment means of each lath  16  onto the column  14  are in the form of a plurality of articulated segments, preferably also metallic or made of a composite material. The segment articulations are designed to accompany deformation of the laths  16  that are sufficiently flexible to be able to deform elastically under the pressure of the back of an occupant sitting in the seat and leaning on the seat back. This deformation of the lath  16  means that the lath can match the shape of the occupant&#39;s back. 
         [0042]    In this case, the segments are preferably all arranged in a single plane, preferably locally orthogonal to the column  14 , the plane in which the associated lath  16  is also located. 
         [0043]    Among these segments, there is a central segment  22  convex backwards, for which the median zone is free to pivot on the column  14  through a pivot link  24 . For example, the central segment  22  is in the form of an arc of a circle. There are two lateral segments  26  allowed for at the opposite ends of this segment  22 , each also convex facing backwards, and the median zone of which is free to pivot about its end associated with segment  22 , through a pivot link  28 . In this case also, each lateral segment  26  is in the form of an arc of a circle, preferably with a radius of less than the radius of segment  22 . 
         [0044]    The two opposite ends of each of the lateral segments  26  are mounted on the associated lath  16 , also free to pivot relative to the pivot link  30 . Consequently, there are four pivot links  30 , all arranged along a line transverse to the single plane passing through the attachment means  20 , the spacing between the two links furthest apart from each other being approximately equal to or slightly less than the width of the seat back. 
         [0045]    With this configuration, the attachment means  20  formed by assembling the segments  22 ,  26  adopt a generally convex shape facing backwards, with a median part that is the part that protrudes furthest back due to symmetry about the column  14  in front of which these means are articulated through the link  24 . Consequently, starting from the structural column  14  and on both sides of it, the seat back  4  extends laterally forwards as can be seen better in  FIG. 4 , which contributes to releasing a large amount of space for the legs  34  of the occupant located behind the seat  1 . 
         [0046]    The rotation axes of the pivot links  24 ,  28 ,  30  are preferably parallel and orthogonal to the single plane. Consequently, in response to efforts applied by the occupant on the seat back, the articulated segments  22 ,  26  will displace by pivoting within this single plane, passing through the associated lath  16 . During this load application, at least some of the segments  22 ,  26  may also deform elastically, even if their flexibility is preferably much less than the flexibility of laths, which are designed to deform much more easily to match the relief of the occupant&#39;s back. In this description, deformation refers to the change in the linear shape of the elements concerned, which may be curved, or the curve may be accentuated, or flattened, or even a double curvature can be applied to the lath, as will be explained below. 
         [0047]    With reference more specifically to  FIGS. 3 and 5 , note that each lath  16  that is not necessarily made of wood, may have an inner core  36  on which the lateral segments  26  are articulated, the core being covered with a foam portion  38  increasing the occupant&#39;s comfort. The core  36  may be made of aluminium or one of its alloys or even carbon fibre. A titanium or steel solution is also possible without going outside the scope of the invention. The foam portion  38  thus acts as cladding for the seat back. In this case, the outside surface of the seat back with which the occupant will come into contact is thus formed by this portion of foam  38  covering the core  36  over the entire length of the lath, along the transverse direction of the seat back. 
         [0048]      FIG. 6   a  shows a diagrammatic view of one of the laths  16  in the unstressed state, as also shown in the previous figures. 
         [0049]      FIG. 6   b  shows a deformation of the lath  16  in a conventional configuration in which the occupant is sitting on the seat  1 , remaining centred relative to the column  14 . In this case, the approximately straight shape of the unstressed lath is deformed to become curved towards the back. This deformation of the linear shape of the lath is made possible by symmetric pivoting of the two lateral segments  26 , the central segment  22  remaining fixed relative to the column. 
         [0050]      FIG. 6   c  shows a case of torsion of the occupant&#39;s back, observed particularly when the occupant turns his or her head sideways or backwards. This causes a double curvature on the lath  16  with an inflection point  40  between the two inverted curvatures in the shape of an elongated S. This inverted curvature advantageously takes place without any discomfort for the occupant, because the lath  16  is preferably not in contact with the column, and it can deform freely accompanying the occupant&#39;s torsion movement without ever bearing on this column. This deformation of the linear shape of the lath is made possible by the non-symmetric pivoting of the two lateral segments  26 , the central segment  22  being able to remain fixed relative to the column. 
         [0051]      FIG. 6   d  shows a deformation of the lath  16  in a configuration in which the occupant sitting in seat  1  is not centred on it, but is slightly offset towards the left of the seat back from the column  14 . In this case, the approximately straight shape of the unstressed lath is deformed to be curved towards the back and towards the right. This deformation in the linear shape of the lath is possible due to the non-symmetric pivoting of the two lateral segments  26 , and by pivoting of the central segment  22  about its link  24  with the column. Finally,  FIG. 6   e  diagrammatically shows that if the force applied by the occupant on the seat back is high, the segments  22 ,  26  can also deform by flattening, the dashed lines in this figure corresponding to their more curved and unstressed state. 
         [0052]      FIGS. 6   a  to  6   e  show different possible behaviours for a lath, it being understood that the laths  16  in a single seat back  4  and their attachment means  20  may have different flexibilities optimised for the part of the back to be supported. 
         [0053]    Obviously, those skilled in the art can make various modifications to the invention as disclosed above, solely as non-limitative examples. In particular, an embodiment is described in which the attachment means comprise three articulated segments, but a larger number of segments would be possible, particularly to obtain greater freedom of deformation for occupant support devices.