FR2688177A1 - VEHICLE SEAT COMPRISING A DEFORMATION MEMBER AS A PROTECTION FOR THE PASSENGER SITTING BEHIND IN THE EVENT OF COLLISION. - Google Patents

Abstract

To absorb the impact of the passenger seated behind the seat in the event of a collision, this seat has a deformation element between the front end of the carcass of its cushion and the underbody. The seat is mounted to tilt on an axis (16) located near the rear end of the frame (12) of the cushion (10). In order to obtain an optimal deformation behavior, the deformation element (17) is composed of a plurality of similar hollow bodies (18) juxtaposed transversely to the direction of travel, made of a fiber composite material and supported by their open ends between two compression plates fixed respectively to the carcass (12) of the cushion and to the base (14). Applicable in particular to buses.

Description

The invention relates to a vehicle seat

  particularly for buses, including a backrest

  and a cushion connected securely and in particular

  a table on the backrest consisting of a cushion carcass and a padding, which cushion is held tilting on a solid base of the vehicle around a tilt axis oriented transversely to the direction of travel and located near the rear end the cushion, viewed in the direction of travel, and is supported on the base by means of a deformation element placed near the front end of the cushion,

view in the direction of travel.

  Such a vehicle seat serves at the same time as a passive restraint for a passenger sitting on

  a vehicle seat placed behind him in case of acci-

  In a collision of the vehicle and the deceleration

  abrupt and extreme ration of the vehicle connected to it, the passenger thrown forward is thus received

  cushioned by the back of the seat in front of him.

  The impact force of the passenger causes a torque around the tilt axis and tends to rotate the cushion towards the underbody. If the force exerted by this torque on the deformation element exceeds a predetermined value, this element starts at 25. sag in a definite way and the cushion rocks through

  the front towards the underbody while the energy

  impact is consumed The passenger is thus restrained

  by the back of the front seat without this

  spikes too high, gener-

injuries.

  On a known vehicle seat of this type (DE 37 27 671 C 2), the deformation element is made of an energy-absorbing foam, surrounded by an envelope and provided with possibilities for attachment to the cushion and the seat. The casing has points for bending and forming fold lines when compressing the foam in the event of an accident. Such a deformation piece produces only a small reduction in impact energy at the start, at the moment when the foam is compressed in block It is then that a strong energy absorption occurs, while the level of the forces applied rises strongly, so that the reduction of energy takes place in its entirety. relatively irregular way on the deformation race available Moreover, the deformation behavior of such a foam part is very difficult to calculate and is therefore not easy to adapt to different types of construction

of the vehicle seat.

  Document DE 30 49 425 C 3 discloses collision protection parts intended for the irreversible absorption of energy under a compressive load, which are produced as elongated hollow bodies with a protective envelope. This hollow body has an approximately constant force-displacement diagram, that is, produces a reduction of energy.

  This hollow body is used to support the bumper vis-à-vis the load-bearing structures of the bodywork or in the area of the front spar of the vehicle for energy absorption purposes. 'impact.

  The object of the invention is to improve a vehicle seat, of the type mentioned at the beginning, so that during the collapse of the deformation element, the impact energy is reduced with maintenance of the forces at one level. as constant as

  In addition, the energy reduction must be able to be calculated and adjusted simply according to the needs of a particular seat construction.

  According to the invention, this result is obtained with a vehicle seat, of the type defined at the beginning, which is characterized in that the element of

  deformation comprises a plurality of hollow bodies

  transverse side-to-side and longitudinally-open, made of a fiber composite material, supported by their ends between two compression plates, one of which is fixed to the carcass of the cushion and the other to the underbody, and

  compression plates are kept

  against the hollow bodies by a connection acting exclusively in the direction of traction between the carcass of the cushion and the base, which allows a reduction in the distance between the compression plates, but prevents an increase in this distance. In the case of the seat according to the invention, due to the constitution of the deformation element of a plurality of hollow bodies axially clamped between compression plates and made of a fiber composite material, the energy reduction is carried out at a level of forces which is constant on the deformation race, so that the impact energy of the passenger is reduced optimally As the connection between the carcass of the cushion and the underbody does not act in the direction of the compression of hollow bodies, it does not cause a change in the level of forces It is only a stable form connection between the underbody and the carcass of the cushion as the hollow bodies are intact and prevents tilting back of the backrest with lifting of the cushion relative to the underbody when pressure is exerted on the support surface

folder.

  Advantageous embodiments of the seat according to the invention with improvements and

  developments of the invention will be described below.

  According to a preferred embodiment of the invention,

  a chamfer, preferably 450, is provided externally on one end of the hollow body Ce

  chamfer avoids a peak load at the beginning of the

  hollow bodies, as can be seen in

  the force-displacement diagram of Figure 5.

  According to a preferred embodiment of the invention, the hollow bodies, preferably in the form of cylindrical tubes, are formed by winding several layers of a composite material.

  fibers, preferably of a plastics material

  forced by glass fibers By the number of layers wound, while the axial length of the tubes is prefixed, it is possible to adjust different levels of forces

for the collapse of the tubes.

  Other features and benefits of

  the invention will become clearer from the description of

  The following description of a nonlimiting exemplary embodiment, as well as the attached schematic drawings, in which: FIG. 1 is a side view of a bus seat;

  Figures 2 and 4 are each a representation

  scaling up of a bus seat detail according to Figure 1 before (Figure 2) and after (Figure 4) an accident; FIG. 3 is an enlarged representation of detail III of FIG. 2 and

  Figure 5 shows the force-displacement characteristic for two different hollow bodies.

  The vehicle seat schematically shown in a side view in FIG. 1, intended for a bus, comprises in known manner a cushion 10 and a backrest 11 which is firmly connected to the seat at an angle of inclination that can be prefixed and generally adjustable. The cushion is usually composed of a carcass, made here as a shell 12, and a padding 13 placed on the shell 12 which is mounted on a base 14 which connects the cushion and the backrest 11 securely to the floor 15 of the vehicle The seat backrest 11 serves at the same time as a passive restraint element for a passenger sitting on the vehicle seat placed in the same row behind the represented seat, in that it is intended to receive this passenger in a damped manner. without injury, in the case of a frontal collision of the vehicle, which requires the definite reduction of the impact energy of the passenger. itle 12 is held tilting on the base 14,

  around a tilting axis 16 oriented transverse-

  in the direction of travel and located near the rear end of the cushion, seen in the direction of travel, and a deformation element 17 is placed between the shell 12

  and the base 14 at the front end of the cushion.

  When the rear passenger is thrown against the backrest 11, the deformation element 17 is biased in compression and sags while the impact energy on the backrest 11 is consumed in a defined manner. The deformation member 17 is more accurately comprised of a plurality of longitudinally open longitudinal hollow members 18 made of a fiber composite material which are arranged adjacent to one another at an equal distance in a transverse row in the direction of travel These hollow bodies 18 are preferably made as tubes with a cross section in the form of a circular ring and are formed of several coiled layers of a plastic material reinforced by

  The hollow bodies 18 may, however,

  to be made also as parallelepipeds with an annular cross-section of square or

  The hollow bodies 18 juxtaposed, are supported by their end faces between two compression plates 20 and 21 The plate 20 is fixed to the shell 1235 of the cushion and the plate 21 is fixed to the base 14. The two plates 20, 21 are prevented from moving relative to each other transversely to the direction of travel. They are furthermore shaped in such a way that a compressive force acting from behind on the backrest 11 and which is deflected by the tilting axis 16, urges hollow bodies 18, in compression,

  exclusively in the direction of the axis of these bodies.

  As can be seen better in the repre-

  On the larger scale of FIGS. 2 and 4, when the hollow bodies 18 are intact (FIG. 21, the shell 12 and the base 14 are firmly connected to each other by a rigid clip 22, so that the backrest 11, to which is connected securely the cushion 10, can not be tilted in the direction of the needles

  of a watch in the representation of Figure 2.

  This clip 22 is fixed on one side to the compression plate 20 and is hooked by the other side freely over the compression plate 21, on the outer side of this plate remote from the hollow body 18. clip 22 holds the two plates 20,

  21 applied against the ends of hollow bodies 18.

  However, the connection established between the cushion 10 and the base 14 by the staple 22 acts only in the

  clockwise in Figures 2 and 4.

  When the hollow body 18 collapses, as indicated schematically in FIG. 4, the staple 22 can escape downwards, which produces no change in the displacement characteristic, determined by the hollow bodies 18 of the deformation element 17 In place of the clip 22, it is also possible to use metal cables stretched between the two compression plates 20, 21 or between the shell 12 of the cushion on the one hand and the base 14 on the other hand FIG. 5 shows the force-displacement characteristic for two different hollow bodies 18, made in the form of tubes. As can be seen, there is a level of forces that is almost constant over the entire deformation path of the hollow bodies 18 and

  presents only a small hint of strength at the beginning.

  The deformation behavior of the whole of the

  deformation 17, thus has substantially the same pace of forces over the entire deformation race. In order to reduce the peak forces at the beginning of the deformation stroke of the hollow bodies 18, a

  end of each of these is externally furnished

  23, as can be seen in FIG. 3. This chamfer 23 also makes it possible to reduce the force peak at the beginning substantially to the level of

  forces on the remaining part of the deformation.

  The operation of the vehicle seat as a passenger restraint in the passenger seat

behind is as follows.

  Under the effect of the sudden extreme deceleration of the vehicle in a frontal collision of the latter, the passenger seated behind the seat, is thrown against the backrest I 1 The impact force of this passenger, acting in the direction of walk-, is applied

  from the back to the backrest 11, deflected by the tilting axis 16 and transmitted as an axial compressive force to the hollow body 18 by the compression plate 25. The hollow bodies sag according to a characteristic

  the force-displacement ratio shown in FIG. 5, so that the impact energy is reduced so

  defined while the level of forces remains

  As already mentioned, the branch of the clip 22, hanging over the plate 21, is not attached thereto, so that the staple 22 entirely deviates downwards together. With the shell 12 of the cushion At the end of the process, the hollow bodies 18 are collapsed, as shown schematically in FIG. 4. For further use of the seat, it must be provided with a

  new deformation element 17.

Claims (7)

  1 Vehicle seat, in particular for self-driving   bus, including a backrest and a cushion, connected solid-   particularly adjustable to the backrest and consisting of a cushion carcass and a padding, which cushion is held tilting on a solid base of the vehicle around a tilt axis oriented transversely to the direction of travel and located near the rear end of the cushion, seen in the direction of   market, and relies on the bedrock   of a deformation element placed near the former   front end of the cushion, viewed in the direction of travel, characterized in that the deformation element (17) comprises a plurality of similar hollow bodies (18) juxtaposed transversely to the direction of travel and open   longitudinal direction, made of a composite material   fiber site, which are supported by their ends between two compression plates (2 G, 21), one of which is fixed to the carcass (12) of the cushion and the other to the underbody (14), and that the plates of compression (20, 21) are held against the hollow bodies (18) by a connection acting exclusively in the direction of traction between the carcass (12) of the cushion and the base (14), a connection which allows a   decrease in the distance between the compression plates   sion (20, 21), but prevents an increase in this distance. Seat according to Claim 1, characterized in that a peripheral chamfer, preferably having a   angle 450, is formed externally on one end of the hollow body (18).   3 Seat according to claim 1 or 2, characterized in that the hollow bodies (18) are each formed   by winding several layers of the fiber composite material.   4 Seat according to any one of the claims   1 to 3, characterized in that the fiber composite material is a plastic material reinforced with glass fibers.   Seat according to any one of Claims 1 to 4, characterized in that the hollow bodies (18)   are made as tubes with a cross section in the form of a circle ring. 6 Seat according to any one of the claims   1 to 5, characterized in that the connection between the carcass (12) of the cushion and the underbody (14) is formed by a rigid clip (22) which is held at one end to the compression plate (20) attached to the carcass (12) of the cushion and the other end of which is hooked freely over the other compression plate (21) on the side of this plate remote from the hollow body (18). Seat according to any one of claims 1 to 5, characterized in that the connection between the carcass (12) of the cushion and the underbody (14> is formed by metal cables fixed to them or to compression plates (20, 21).