Seat especially for aeroplanes comprising an adjustable seating plate and a seatback

The seat comprises means for controlling movement of the seating plate ( 7 ) between a first extreme position (A) adapted to for small passengers, a second extreme position (B) adapted to tall passengers so that in all the positions, the distance d 1 , d 2 , d 3 between the seatback ( 6 ) and the front edge ( 7 a ) of the seating plate ( 7 ) corresponds to the distance between the base of the back and the hollow portion of the knee of the passengers, and simultaneously the distance (a 1 , a 2 , a 3 ) between the front edge ( 7 a ) of the seat plate and the floor ( 5 ) corresponds to the distance between the hollow portion of the knee and the sole of the foot of the passengers

The aircraft plane seat comprises a fixed structure 1 including a hook-shaped element 2 and an element known as a foot, both elements crossing at a point 4 . A seatback 6 and an adjustable seat plate 7 are secured to the fixed structure 1 . In accordance with the invention, the seat comprises first means for controlling the movement of the seat plate 7 between: a first extreme position A adapted to passengers of a small predetermined size, a second extreme position B adapted to passengers of a tall predetermined size, the intermediate positions, such as C, between the two extreme positions A, B being adapted to passengers having intermediate sizes so that in all the positions: the distance d 1 , d 2 , d 3 between the seatback 6 and the front edge 7 a of the seat plate 7 corresponds to the distance between the base of the back and the hollow portion of the knee of the passengers in a seated position on the seat and having the size corresponding to one of said positions and, simultaneously, the distance a 1 , a 2 , a 3 between the front edge 7 a of the seat plate 7 and the floor 5 corresponds to the distance between the hollow portion of the knee and the sole of the foot of the passengers having the size corresponding to said position. The extreme positions A, B are determined so that the latter as well as the intermediate positions, such as C, are adapted to 95% of the sizes of passengers, namely sizes between about 1.61 m and 1.88 m. According to a first embodiment shown on FIGS. 1 to 3 , the seatback 6 includes a lumbar support 8 which is fixed with respect to said seatback and simultaneously adjustable by said first means with the seat plate so that in all the positions, the distance (b 1 , b 2 , b 3 ) between the seat 7 and the centre of the lumbar support 8 corresponds to the distance between the buttocks and the centre of the lumbar zone of the passengers having the size corresponding to said position. According to said first embodiment (see FIG. 3 ), the translation movement of the seatback 6 and that of the seat plate 7 are each guided by a slide 10 , 11 . The seatback 8 and the seat plate 7 can comprise two parallel slides forming a part of the structure of the seatback and the seat plate. The movement for lifting the seat plate 7 is controlled by two fixed slides, such as the one designated by 12 adjacent to the front edge 7 a of the seat plate and cooperating with said front edge 7 a so as to slightly lift the latter during translation towards the front of the seat plate 7 . Each slide 12 can be embodied at the front of the fixed structure of the seat as shown on FIG. 3 , with a tilt of approximately 45°. The seat comprises close to the rear edge of the seat plate 7 and the lower edge of the seatback 6 , an activator 13 whose outlet shaft 14 extends transversally with respect to the seat and bears an upper arm 15 fixed jointed by a connecting rod 16 to the body of the translation slide 10 of the seatback 6 , and a lower arm 17 fixed jointed by means of another connecting rod 18 to the seat plate 7 . Moreover, the rod of the translation slide 10 of the seatback 6 is connected at its lower portion 19 to the body of a jack 20 whose rod is fixed jointed at 21 to the structure of the seat. The rod of the slide 10 is in addition integral with an arm 22 fixed jointed onto the outlet axis 14 of the activator 13 , said arm 22 being extended towards the front by an extension 23 fixed jointed at 24 to the fixed structure of the seat. According to a second embodiment shown on FIGS. 4 and 5 , the seatback 6 of the seat does not include a lumbar support 8 . According to said embodiment (see FIG. 4 ), only the seat plate is thus adjustable by the first control means. According to this second embodiment (see FIG. 5 ), the translation movement of the seat plate 7 is guided by a slide 11 . The lifting movement of the seat plate 7 is controlled by two fixed slides, such as the one designated by 12 adjacent to the front edge 7 a of the seat plate and cooperating with said front edge 7 a so as to slightly lift the latter during translation towards the front of the seat plate 7 . According to said second embodiment, the seat plate 7 is telescopic. The seat 7 plate has its rear edge articulated around an axis 14 a integral with the seatback 6 and its front edge 7 a is arranged so as to slide upwards and towards the front with respect to the fixed structure 1 . The seat plate 7 comprises an activator 13 , of axis 14 b , placed closed to the front edge 7 a of the seat plate 7 . Said activator 13 is placed so as to ensure telescoping of the seat plate 7 . To this effect, it comprises an activating pinion 30 a associated with a rack 30 b. Moreover, the seatback 6 is linked to the body of a jack 20 whose rod is fixed articulated at 21 to the structure of the seat. According to another embodiment (not shown), the seatback comprises a lumbar support 8 which is fixed with respect to the seatback 6 and able to be adjusted independently of the seat plate 7 . The activator 13 can be an electric motor or a manual control device. The seat of the invention can further include an articulated leg-rest 9 articulated close to the front edge 7 a of the seat plate 7 able to be adjusted according to the size of the passengers and able to be have its inclination adjusted manually or by motorised means. In addition, the seatback 6 can include a headback also able to be adjusted manually or by motorised means, possibly independently of the seatback 6 , according to the size of the passengers. The seat of the invention further comprises second means to simultaneously control the movement of the seatback 6 and seat plate 7 between a first said “takeoff and landing” position in which the seatback 6 is slightly tilted backwards and the seat plate is slightly tilted downwards, and said “rest” positions R 1 , R 2 , etc., in which the seat back 6 is more tilted towards the rear and the seat plate 7 is further tilted downwards. Said positions are shown on FIG. 2 in which the seat is shown according to its first embodiment. The second control means are independent of the first control means so that the activation of the second control means does not modify the adjustment of the position of the seat plate 7 and seatback 6 (first embodiment), or the adjustment of the seat plate (second embodiment) obtained by the activation of the first control means adapted to the size of the passenger. In other words, the distances such as a 1 , a 2 , a 3 ; b 1 , b 2 , b 3 ; and d 1 , d 2 , d 3 obtained by the first control means are not modified when tilting of the seatback and the seat plate is modified. The functioning of the seat which has just been described shall now be explained in relation to the first embodiment of said seat shown on FIGS. 1 to 3 . A passenger of with a height equal for example to 1.75 m sits on the seat of the invention adjusted to the position A, that is adapted to those individuals whose height is only 1.61 m. The passenger is then aware that the hollow portion of his knee is situated basically beyond and above the front edge 7 a of the seat plate 7 and that the lumbar support 8 is situated too low down. The passenger then activates the activator 13 which moves the slides 10 and 11 . The seatback 6 then moves upwards and the seat plate moves to the front. The rotation of the shaft 14 of the activator 13 lifts the rear part of the seat plate 7 backwards whereas the front of the latter is lifted up by means of the tilted slide 12 . The passenger stops operating the means for controlling the movement of the seatback 6 and the seat plate 7 when he has found the optimal position corresponding to his height of 1.75 m. This optimal position approximately corresponds to the intermediate position C shown on FIG. 1 . In said position, the sole of the feet of the passenger rests onto the floor 5 . The hollow portion of his knees is in support without going beyond the front edge 7 a of the seat plate 7 . The lumbar support 8 occupies the correct position with respect to the lumbar vertebrae of the back of the passenger. From the above-mentioned “landing-takeoff” position, the passenger can select the rest positions R 1 , R 2 , etc,. shown on FIG. 2 . When the seatback 6 and the seat plate 7 respectively move backwards and downwards, the front edge 7 a does not move so that the hollow portion of the knee stays in the ideal position. During said movement to a “rest” position, the tilting of the seatback 6 backwards and the tilting of the seat 7 downwards is controlled by the jack 20 of the shaft. The functioning of the seat according to the second embodiment is similar to the one which has just been described, except for the adjustment of the lumbar support 8 , which is not provided in said embodiment. It goes without saying that the invention is not limited to the embodiment examples which have just been described and many modifications can be made without departing from the context of the invention. Thus, the passenger could have on the seat a keyboard able to display his height and also an electronic circuit automatically controlling the movement of the seatback and the seat plate towards the position corresponding to the displayed height. From said position, the passenger would be able to refine the adjustments so as to find the optimal position. Moreover, the jack 20 , which controls the tilting of the seatback and the seat plate, thus allowing adjustment of the “comfort” position, can be a linear motor or a mechanical jack. The invention can be applied to any type of seat, other than aircraft seats and in particular seats for motor vehicles.