Abstract:
The invention relates to a seat for a vehicle, that includes a headrest with a headstall for supporting the head of a passenger in the seat, wherein the occupant may or may not wear a protection helmet depending on the circumstances. The headstall can assume at least three stable positions: a first position for the cervical support of the head of the seat passenger in which the headrest provides a cervical support function with or without wearing a helmet; a second position for the occipital support of the head of the seat passenger in which the headrest provides an occipital support function without wearing a helmet; a third position for the occipital support of the head of the seat passenger in which the headrest provides an occipital support function while wearing a helmet.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of International Application PCT/FR2008/051034 filed on 10 Jun. 2008, which claims priority to French Application No. 07 04275 filed on 15 Jun. 2007, the disclosures of which are incorporated by reference in their entireties. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The aspects of the disclosed embodiments relate to a head restraint for a vehicle seat, in particular an aircraft seat. More particularly, the aspects of the disclosed embodiments relate to a head restraint intended to be installed on seats whose occupants require head support both when wearing a helmet and when not. 
         [0004]    2. Brief Description of Related Developments 
         [0005]    A head restraint for a vehicle seat is generally produced so as to provide a seat occupant with comfort and safety. This head support, which continues the backrest of the seat, such as for example a pilot&#39;s seat in the cockpit of an aircraft, supports the pilot&#39;s head and helps to reduce cervical tension due to the weight of the pilot&#39;s head when he is performing an operating or flying task. 
         [0006]    In order to provide greater comfort and to fulfill their role in different use configurations, existing head restraints are adjustable for height and/or for forward/rearward inclination in order to adjust the position of the head restraint with respect to the pilot&#39;s head in order to provide either occipital or cervical support. 
         [0007]    However, the means for adjusting the height and/or inclination of these head restraints are usually controlled by separate mechanisms, and this impairs rapid manipulation of these means. 
         [0008]    In addition, these head restraints, when they need to be used sometimes in a configuration where the pilot is not wearing a helmet and sometimes in a configuration where the pilot is wearing a helmet, such as for example on board a military aircraft, are badly suited to one or the other of these configurations, since they cannot be adjusted to take account of the extra occipital thickness created by the helmet. 
         [0009]    The implementation of a head restraint which combines the two adjusting possibilities in a single mechanism while being able to support the pilot&#39;s head both with and without a helmet is thus significant for simplifying the adjusting means. 
       SUMMARY 
       [0010]    According to one aspect of the disclosed embodiments, a vehicle seat has a backrest on which a head restraint is fitted, said head restraint having a cushion for supporting the head of a seat occupant who may or may not, depending on the circumstances, be wearing a protective helmet, characterized in that the cushion has at least three stable positions: 
         [0011]    a first position for cervical support of the seat occupant&#39;s head, in which position the head restraint provides cervical support whether or not a helmet is being worn, 
         [0012]    a second position for occipital support of the seat occupant&#39;s head, in which position the head restraint provides occipital support when a helmet is not being worn, 
         [0013]    a third position for occipital support of the seat occupant&#39;s head, in which position the head restraint provides occipital support when a helmet is being worn. 
         [0014]    Advantageously, the cushion has a first occipital support surface when the cushion is in the second or third position and a second cervical support surface when the cushion is in the first position. 
         [0015]    The position of the cushion is changed between the at least three stable positions by means of rotations about a single rotational axis, the positions of the support surfaces of the cushion in each of the at least three stable positions of said cushion being determined by: 
         [0016]    positioning the rotational axis at a height with respect to the seat substantially between the hollow of the nape and an upper part of the nape of a pilot of generally average size, 
         [0017]    positioning the first surface with respect to the rotational axis, 
         [0018]    positioning the second surface with respect to the rotational axis. 
         [0019]    Preferably, the cushion has two translational positions along the rotational axis: a stable position in which the cushion is locked and an unstable position in which the cushion can rotate freely about the rotational axis. 
         [0020]    In order for the cushion to rotate, said cushion is attached to a first hollow rotary shaft, the axis of which coincides with the rotational axis and which slides and revolves about a second, coaxial rotary shaft held such that it is fixed at the ends by two mutually parallel plates positioned laterally on an upper part of the seat backrest. 
         [0021]    The first rotary shaft has at one of its ends a first revolving component attached to said first rotary shaft and having at least one locking pin which engages in an aligned recess, among a plurality of recesses, made in a first plate, when the cushion is in a stable position. 
         [0022]    Preferably, spring means are positioned around the second rotary shaft between an inner face of the first plate and an outer face of a second revolving component located at another end of the first rotary shaft. In order to unlock the cushion and modify the position of the cushion from one stable position to another, said spring means are compressed by pushing said cushion laterally and the at least one locking pin is removed from its recess. 
         [0023]    One aspect of the disclosed embodiments also relates to a head restraint for a vehicle seat, having a cushion for supporting the head of a seat occupant, characterized in that the cushion has at least three stable positions: 
         [0024]    a first position for cervical support of the occupant&#39;s head, in which position the head restraint provides cervical support whether or not a helmet is being worn, 
         [0025]    a second position for occipital support of the seat occupant&#39;s head, in which position the head restraint provides occipital support when a helmet is not being worn, 
         [0026]    a third position for occipital support of the seat occupant&#39;s head, in which position the head restraint provides occipital support when a helmet is being worn. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The detailed description of the disclosed embodiments is given with reference to the figures, in which: 
           [0028]      FIG. 1  shows a schematic view of a head restraint according to an aspect of the disclosed embodiments, 
           [0029]      FIG. 2  shows an exploded view of an adjusting mechanism for the head restraint according to the disclosed embodiment, 
           [0030]      FIG. 3   a  shows a profile view of a seat, and of its occupant, having a head restraint according to the disclosed embodiment illustrating two positions of the head restraint for occipital support and cervical support for a short occupant not wearing a helmet, 
           [0031]      FIG. 3   b  shows a profile view of a seat, and of its occupant, having a head restraint according to an aspect of the disclosed embodiments illustrating two positions of the head restraint for occipital support and cervical support for a short occupant wearing a helmet, 
           [0032]      FIG. 4   a  shows a profile view of a seat, and of its occupant, having a head restraint according to an aspect of the disclosed embodiments illustrating two positions of the head restraint for occipital support and cervical support for a tall occupant hot wearing a helmet, 
           [0033]      FIG. 4   b  shows a profile view of a seat, and of its occupant, having a head restraint according to an aspect of the disclosed embodiments illustrating two positions of the head restraint for occipital support and cervical support for a tall occupant wearing a helmet, 
           [0034]      FIG. 5   a  shows a profile view of a seat, and of its occupant, having a head restraint according to an aspect of the disclosed embodiments illustrating two positions of the head restraint for occipital support and cervical support for a short pilot not wearing a helmet, when the backrest is inclined toward the rear, and 
           [0035]      FIG. 5   b  shows a profile view of a seat, and of its occupant, having a head restraint according to an aspect of the disclosed embodiments illustrating two positions of the head restraint for occipital support and cervical support for a tall pilot not wearing a helmet, when the backrest is inclined toward the rear. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    A head restraint  1  according to the disclosed embodiment and as illustrated in  FIG. 1  is intended to be fitted on the upper part  42  of a seat backrest  4 , continuing said backrest, and has a cushion  2  able to support the head  51  of an occupant  5  of the seat. 
         [0037]    The exemplary embodiment illustrated in  FIGS. 1 to 5   b  is described in the case of a head restraint  1  intended to be fitted on a military aircraft pilot&#39;s seat, but the aspects of the disclosed embodiment can also be applied to any seat whose occupant needs head support both when wearing a helmet and when not. 
         [0038]    The cushion  2  has: 
         [0039]    a first support surface  21  shaped to fit the curvature of the occiput of the head  51  of the pilot  5 , 
         [0040]    a second support surface  22  shaped to fit the curvature of the nape of the head  51  of the pilot  5 . 
         [0041]    In order to adjust the head restraint to the morphology of the pilot and to his use or non-use of a helmet  52 , the cushion  2  is positioned with respect to the head  51  of the pilot  5  substantially along the X and Z axes in the reference frame of the aircraft, that is to say by moving it forward/rearward (X axis) or upward/downward (vertical or Z axis) between at least two stable positions: 
         [0042]    a characteristic cervical support position, and 
         [0043]    a characteristic occipital support position. 
         [0044]    To perform adjustments in the X or Z directions, the head restraint  1  has an adjusting means  6  positioned between the upper part  42  of the seat backrest  4  and the cushion  2 . 
         [0045]    The adjusting means  6 , as illustrated in  FIG. 2 , has a first, hollow rotary shaft  61  which slides and revolves around a second, coaxial rotary shaft  65 , said second rotary shaft extending along a rotational axis  69  to occupy all or some of a width of the seat backrest  4 . 
         [0046]    The second rotary shaft  65  is held such that it is fixed at the ends  66   a ,  66   b  by two mutually parallel plates  31   a ,  31   b  positioned laterally on a thickness of the seat backrest  4  along the X axis. 
         [0047]    The first rotary shaft  61 , which is substantially shorter than the second rotary shaft  65 , has at each of its ends Ma,  64   b  a revolving component  67   a ,  67   b , for example in the form of a disk centered on each end Ma,  64   b.    
         [0048]    The plate  31   a , or  31   b , has a hollowed out region  312   a , or  312   b , creating a housing to hold the component  67   a , or  67   b , respectively. 
         [0049]    Spring means  62 , for example a spring, positioned around the second rotary shaft  65  between an inner face  311   a  of the first plate  31   a  and an outer face  671   a  of the revolving component  67   a , exert a pressure on the outer face  671   a . Said spring means are partially prestressed when the cushion  2  is in a stable position. 
         [0050]    Once it has been assembled, the second rotary shaft  65  is held such that it is fixed in bearings at the two plates  31   a ,  31   b . The revolving components  67   a ,  67   b  are attached to the first rotary shaft  61 , said first rotary shaft sliding and revolving around the second rotary shaft  65 . 
         [0051]    The revolving component  67   b  has at least one locking pin  63 , located at a radius r from the end  64   b  of the rotational axis  69  of the rotary shaft  61 , on an outer face  671   b  opposite an inner face  311   b  of the second plate  31   b.    
         [0052]    The second plate  31   b  has recesses  33  positioned so as to be in a circle of radius r centered on the rotational axis  69  of the second rotary shaft  65 , the recesses  33  being dimensioned such that the at least one locking pin  63  easily engages in them without excessive play. The at least one locking pin  63  may have, for example, a slightly rounded end or a bevel. 
         [0053]    Preferably, the revolving component  67   b  has two locking pins  63 , each locking pin  63  engaging with a recess  33  in order to improve the locking of the cushion  2 . 
         [0054]    The cushion  2  is attached to the first rotary shaft  61 , for example by two rods  32 , as illustrated in  FIG. 1 , which are substantially parallel and fixed to the rotary shaft  61 , substantially perpendicular to said rotary shaft  61 , said rods having a sufficient area of contact with the rotary shaft  61  to provide sufficient strength with no risk of excessive bearing. 
         [0055]    When the cushion  2  is in a stable position, the spring means  62  are substantially prestressed between the component  67   a  and the plate  31   a , the component  67   b  is in contact with the plate  31   b  at its outer face  671   b  and the at least one locking pin  63  is positioned in a recess  33  in the plate  31   b , the effect of this being that the cushion  2  is held in a stable position. In order to modify the position of the cushion  2  from one stable position to another, the pilot  5  unlocks the current stable position by pushing the cushion  2  sideways, from the end nearest the plate  31   b  having the recesses  33 , so as to compress the spring means  62  and to remove the at least one locking pin  63  from its recess  33 . Advantageously, one hand is used for pushing. 
         [0056]    During pushing, the first rotary shaft  61  and the revolving components  67   a ,  67   b  undergo a translational movement by sliding along the second rotary shaft  65 , and the spring means  62 , which were holding the at least one locking pin  63  in position in one of the recesses  33  in the second plate  31   b , are compressed by the component  67   a . By means of this translational movement which also involves the component  67   b , the at least one locking pin  63  is released from the recess  33  in the plate  31   b  in which it was engaged before translation. The cushion  2 , attached to the first rotary shaft  61 , is thus free to pivot, the pressure on said cushion continuing to compress the spring means  62 . When the cushion  2  has reached a desired position, the sideways pressure on said cushion is released. The spring means  62  expand, pushing back the first rotary shaft  61  and the revolving components  67   a ,  67   b  until the component  67   b  comes into contact with the plate  31   b  at its outer surface  67   b . The at least one locking pin  63  enters one of the aligned recesses  33  in the plate  31   b , automatically locking the cushion  2  in position, the new position becoming stable. 
         [0057]    Advantageously, the rotational axis  69  of the first rotary shaft  61  is positioned substantially at a level of the hollow of the nape of a pilot of average size, and preferably in an upper part of the nape, that is to say substantially above the hollow of the nape. Thus, rotating the cushion  2  enables a forward/rearward and upward/downward combination in a single, angular, movement. 
         [0058]    Advantageously, the self-locking stable positions prevent the head restraint  1  rocking forward, for example when another crew member leans on the cushion  2 . 
         [0059]    When the cushion  2  is in a substantially high position, the occiput of the head  51  of a pilot  5  is supported by the first surface  21  of the cushion  2 , whether the pilot is wearing a helmet or not. 
         [0060]    When the cushion  2  is in a low forward position, the nape of the head  51  of the pilot  5  is supported by the second surface  22  of the cushion  2 . Thus, said cushion may be placed in a low position in order to partially relieve the head  51  of the weight it bears, even when the pilot  5  is wearing a helmet, since the helmet  52  does not cover the nape. 
         [0061]    Advantageously, the recesses  33  made in the plate  31   b  determine a set of angular positions of the cushion  2 , enabling said cushion to be adapted easily to the morphology of the pilot  5 , whether or not said pilot is wearing a helmet  52 , and thus to the extra occipital thickness created by said helmet, during flying tasks. Thus, the head restraint  1  can be adapted to numerous pilot sizes, in particular for pilots between 1570 mm and 1905 mm and according to the standards MIL-HDBK-759C, which are generally followed by other standards used for designing cockpits. 
         [0062]    The positions of the cushion  2  for occipital support and cervical support are different for a tall pilot than for a short pilot or a pilot of average size, as illustrated in  FIGS. 3   a  to  4   b . In addition, the position of the cushion  2  for occipital support is different depending on whether the pilot is wearing a helmet or not. 
         [0063]      FIG. 3   a  illustrates the occipital support and the cervical support for a short pilot not wearing a helmet, while  FIG. 3   b  illustrates the same two supports for a short pilot wearing a helmet. 
         [0064]      FIG. 4   a  illustrates the occipital support and the cervical support for a tall pilot not wearing a helmet, while  FIG. 4   b  illustrates the same two supports for a tall pilot wearing a helmet. 
         [0065]    Advantageously, when the seat is inclined rearward, the cushion  2  can also be positioned to provide the occipital support or cervical support necessary for increasing the comfort of the pilot and more particularly when said pilot is in a rest position, whatever the morphology of the pilot, as illustrated in  FIGS. 5   a  and  5   b.    
         [0066]    Advantageously, in order to improve access to the controls of a ceiling panel, the cushion  2  has in addition a stable position, in a high position substantially to the rear, in which the pilot  5 , whether or not he is wearing a helmet, is not hindered by contact with the cushion  2 . 
         [0067]    Furthermore, when the cushion  2  is in the high position to the rear, it limits the rearward movement of the head  51  of the pilot  5  when said head is subjected to possibly significant accelerations or vibrations, thereby reducing the risk of injuries or musculoskeletal problems in the region of the cervical spine. 
         [0068]    In order to improve accessibility to and the visibility of the ceiling panel, the cushion  2  is narrower than the seat backrest. 
         [0069]    Preferably, the plates  31   a ,  31   b  are spaced apart at a distance smaller than the width of the seat backrest in order to enable the attachment of a suspending means  43 , for example a hook, on one of the ends of the upper part  42  of the seat backrest  4  in order to attach the helmet thereto when said helmet is not being used by the pilot, keeping said helmet readily accessible from the seat. 
         [0070]    In order to protect the head  51  of the pilot  5  from the adjusting means  6 , a frame  3 , bearing on the two plates  31   a ,  31   b , covers the adjusting means  6  and has a form adapted to the form of the cushion so as not to hinder movements of the cushion  2  when the latter is rotating. Said frame has extensions  34  enabling it to be attached to the upper part  42  of the seat backrest  4 . 
         [0071]    Thus, the head restraint  1  can be used by any pilot and for different functions: as a place for resting the head during the flying phase or as a place for resting the nape during the rest phase, whether or not the pilot is wearing a helmet, the change from one function to another being carried out by way of a simple manipulation of the head restraint with one hand, a sideways push to unlock the cushion, a rotation to select the position and then releasing the cushion to lock it again. 
         [0072]    The head restraint according to the disclosed embodiments thus enables a pilot, whether he is wearing a helmet or not, to combine various vertical or inclination adjustments by means of a single mechanism and a single degree of freedom, rotation.