FR2843343A1 - Active head support for vehicle seat comprises rear fixed part connected to seat back and front part able to move frontward, under action of spring, in telescopic guide - Google Patents

Abstract

The head support comprises a rear fixed part (2) connected to the back of the seat and a front part (3) which defines the head support surface and can move frontward relative to the fixed part under the effect of a spring (5). There is a telescopic guide (4) for the horizontal translation of the movable part. There are retaining means (6) for holding the movable part in the rear position controlled by a release actuator (10).

Description

Active headrest for rolling vehicle seat.

  The present invention relates to an active headrest for a seat of a rolling vehicle, comprising a bearing surface for the head 5 of the seat occupant, means for connecting the headrest to the seat back that said bearing surface is movable between a rear position and a front position, and actuating means for bringing said bearing surface from said rear position to said

forward position.

  During a rear impact, the head of the occupant of a motor vehicle seat undergoes, with respect to the trunk which is pressed against the back of the seat, an acceleration towards the rear capable of causing cervical trauma, phenomenon better known as

name of "whiplash".

  To limit the damage caused by this phenomenon, at least the front seats of motor vehicles are currently

  systematically fitted with a headrest at the top of the backrest.

  However, at least for the driver of the vehicle, a certain distance of the order of 60 mm between the headrest and the head is generally considered to be necessary for driving comfort. Therefore, despite the presence of the headrest at the top of the backrest, the whiplash phenomenon occurs in the event of an impact

  back and can lead to cervical damage.

  This is the reason why it has already been proposed to associate a so-called "reactive" headrest with the seat (see for example WO 98 09 838, US 6 024 406, DE 199 61 618, EP 1 026 029, EP 1 084 901). Such a reactive headrest includes an actuation mechanism incorporated into the seat for advancing the headrest, this mechanism being activated

  by the back or the pelvis of the seat occupant in the event of a rear impact.

  These systems, which are reusable, do not protect the seat occupant in all configurations and all driving positions. In addition, the actuating mechanism of the headrest cannot be integrated into seats with thin backrests, for example seats comprising a back shell and

  a thin packing material.

  Another proposed solution consists in integrating an energy absorbing element, plastically deformable, in the structure of the seat to allow a greater displacement of the back of the occupant in the backrest ("WHIPS" system of Volvo). In the event of a rear impact, initially, the bottom of the seat back recedes and the occupant's head comes to rest on the headrest. Then the seat and the headrest perform a movement parallel to the body, then the whole backrest reclines so that the body is held

  in a state of equilibrium. Thus, the relative movement of the head is limited relative to the thorax, which reduces the "whiplash" effect.

  Depreciation is more progressive, because it takes place over several tens of centimeters. This solution is restrictive, because it requires the replacement of the deformed element after the rear impact.

  One could also consider modifying the structure of the seat back by increasing its thickness, thus allowing the occupant's shoulders to sink deeper into the back, so as to make up for the initial head-headrest play. This solution is also restrictive, because it implies that no backrest structure interacts with the occupant's shoulders when the chest is moved. Nor is it applicable to a thin-back seat design, for example with a seat shell

  backrest and thin upholstery material.

  Finally, there are many proposals for so-called "active" head restraints, consisting in using a mobile head restraint between a rear position and a front position and actuation means controlled, for example by shock or collision, to move the headrest to the front position under the action of springs, electric, pneumatic actuators, or the like (see for example

  DE 197 31 058, WO 01 23 210, US 5 694 320, US 6 199 900, US 6 196

580, EP 1 055 553).

  The main drawback of all these active head restraints, which are also found on most reactive head restraints, consists in the fact that these head restraints are mostly movable forwards by pivoting. around an axis located below the headrest, at the level of the seat back, so that the speed of advance of the support surface for the head and the amplitude 5 of the movement of advance of this support surface, for a given pivot angle, are a function of the height adjustment of the headrest, so that the action of these head restraints is difficult to control on occupants of different sizes and also when the The headrest was not or was incorrectly adjusted in height depending on the size of the occupant. The fact that on some of these pivoting head restraints, the pivoting movement forward is accompanied by a movement

  does not change this situation.

  The subject of the present invention is an active headrest

  allowing a controlled action on the head of the occupant, whatever the size of the latter.

  The subject of the invention is also an active headrest which can be integrated without problem into a seat having a thin backrest consisting, for example of a back shell and of a material of

thin packing.

  The invention further relates to an active headrest comprising a non-return system which slows down the force of the headrest

  on the head and automatically locks the headrest in the front position.

  Finally, the invention relates to an active headrest which can

be rearmed at will.

  The active headrest according to the invention, intended for a rolling vehicle seat, comprises a bearing surface for the head of the seat occupant, means for connecting the headrest to the seat backrest, so that said bearing surface is movable between a rear position and a front position, and actuating means 30 for bringing said bearing surface from said rear position to said front position. The headrest comprises a fixed rear part intended to be connected to the seat backrest and a front part which defines said bearing surface and is movable in translation towards the front relative to

  the fixed part under the effect of the actuating means.

  The subdivision of the headrest into a fixed rear part and a front part movable in translation relative to the fixed part means that the movement of the mobile part forwards is perfectly controlled, both in speed and in amplitude, regardless of the size of the seat occupant. It is thus in particular possible to give the headrest a sufficient height so that the headrest is suitable for occupants of different sizes, without requiring any height adjustment. The fixed part and the mobile part of the headrest

  can be integrated into the same extendable cover.

  Preferably, the fixed part and the mobile part of the headrest comprise complementary means for guiding in translation (horizontal or substantially horizontal) the mobile part on the

fixed part.

  To improve the compactness of the headrest, the means for guiding in translation can preferably be telescopic means. The actuating means may comprise any mechanical, electrical or pneumatic means, preferably at least one spring which, in the rear position of the movable part, is prestressed and biases the movable part towards the front position, retaining means for maintain the movable part in the rear position and triggering means controlled to release the means

of restraint.

  The spring may preferably comprise a mechanical spring, for example a helical compression spring which can then be incorporated into the telescopic guide means, which may advantageously comprise at least two guides located on the

two sides of the headrest.

  The triggering means controlled to release the retaining means can comprise pneumatic means,

  hydraulic, mechanical or preferably an electric actuator.

  According to a preferred embodiment, the headrest further comprises a non-return system, preferably a ratchet system,

  which blocks the moving part in the front position.

  The headrest preferably further includes a rearming system to suppress the action of the non-return system and allow the movable part to be brought back from the front position to the rear position, against the effect actuation means, and to retain it in the rear position. Referring to the appended schematic drawings, there will be described below in more detail an illustrative and nonlimiting embodiment of an active headrest according to the invention; in the drawings: FIG. 1 is a block diagram illustrating the operation of the headrest according to the invention; and FIGS. 2 and 3 are schematic views from above of

  the head restraint in the non-activated position and in the activated position.

  As illustrated in the drawings, an active headrest 1 according to the invention comprises a fixed rear part 2 connected to the backrest, not shown, of a motor vehicle seat, and a front part 3 mounted movably in translation by guide means 4 on the fixed part 2, so as to be movable in horizontal translation relative to the fixed part 2, between a rear position visible in FIG. 2 and in solid lines in FIG. 1 and a visible front position 20 in FIG. 3 and in dashed lines in FIG. 1 As it appears above all in FIGS. 2 and 3, the bearing surface 3a of the movable part 3 is, in the rear position of the part 3, at a distance behind the head of the seat occupant and, in the forward position, substantially in

  contact with the occupant's head.

  The headrest 1 also comprises means 5 shown in the form of at least one pre-stressed spring 5 between the rear part 2 and the front part 3, when the latter is in the rear position, to urge the moving part 3 towards the front position. The headrest also comprises retaining means 6 for retaining the movable part 3 in the rear position, against the action of the spring 5. According to FIG. 1, the retaining means 6 here comprise , on the movable part 3, a lug 7 and on the fixed part 1 a latch 8 biased by a spring 9 towards the position in which the latch 8 cooperates with the lug 7 for the purpose of retaining the movable part 3 in the rear position , against the action of the spring 5. The latch 8 can also be activated for its movement against the action of the spring 9, for the release of the chin 7, by an actuator 10 consisting , for example, by an electromagnetic actuator mounted on the fixed part 2. It should be noted that the flange 7 and the latch 8 have a profile (for example in trapezoid) such as the flange 7, when the movable part 3 is pushed towards the rear position against the action of the spring 5, can repel tighten the latch 8 against the action of the spring 9, the latch 8 then being brought back by the spring 9

  in the retainer position of the chin 7 (resetting the head restraint).

  In Figures 2 and 3, which do not show the retaining means 6 of Figure 1, it is recognized that the guide means 4 are constituted by two telescopic guides located on the opposite lateral sides 15 of the headrest 1 , the springs 5 being integrated into these guides 4. Furthermore, in FIGS. 2 and 3, in which the fixed part 2 is symbolized by a line in dashed lines, it appears that the mobile part 3 bears, on the side facing towards the head of the occupant of the seat, a filling material 11 preferably consisting of a foam

viscoelastic character.

  Such deformable materials have the distinction of being flexible at low deformation rates and becoming harder at higher deformation rates. Such viscoelastic materials thus provide good comfort and, at the same time, limit the insertion of the head into the headrest (in the lining 11), and also avoid rebounds of the head during the activation of the headrest. Also recognized in Figures 2 and 3 an anti-return system 12, here constituted by a pawl 13 articulated at 14 on the movable part 3 and biased by a spring 15 against a rack 16. The latter comprises teeth preferably teeth of saw, so that the pawl 13, during the passage of the movable part 3 from the rear position according to FIG. 2 to the front position according to FIG. 3, under the action of the springs 5, after release of the retaining means 6 for actuator 10 (see Figure 1), can "jump" the teeth, but

  prevents any backward movement of the moving part 3.

  With a view to manual resetting of the headrest, which precisely involves a return of the movable part 3 to the rear position with compression of the springs 5, according to FIG. 2, until the blocking in this position by the retaining means 6 according to FIG. 1, the rack 16, constituted by a rod, is mounted mobile in rotation about its axis under the action of a lever 17. Preferably, the rod constituting the rack 16 is angularly stressed around

  of its axis by a return spring not shown towards the position in which its teeth are located opposite the pawl 13, so that when the lever 17 is released, the rack 16 is automatically repositioned in the non-return position, according to the 15 Figure 2.

  Finally, it appears from FIGS. 2 and 3 that the headrest 1 as a whole is integrated in an extendable cover 18, common to both

parts 2 and 3.

  The triggering of the system, at the level of the actuator 10, 20 can be done for example in the usual way on the basis of displacement or acceleration information. This information can be obtained for example by the displacement of the rear bumper of the vehicle, by the movement of the occupant's chest in the backrest, or also by ultrasonic reversing sensors, located for example in the bumper. rear of the vehicle. The acceleration information can be obtained for example by the airbag triggering computer or by separate acceleration sensors. In any case, the information thus obtained can preferably be processed and analyzed by a control algorithm to verify that the shock that has occurred (or is about to occur)

  produce) requires activation.

  In view of the subdivision of the headrest into a fixed rear part and into a mobile front part in horizontal translation relative to the fixed part, the forward movement of the bearing surface 3a of the mobile part is perfectly controllable, regardless of the height adjustment position of the headrest for

  adaptation to the size of the seat occupant.

  The headrest according to the invention can also, because of its structure and its functioning, be a headrest not adjustable in height, having a height sufficient to suit occupants of

different sizes.

  Furthermore, the headrest according to the invention is particularly suitable for seats with a thin back, for example seats comprising a back consisting of a back shell and a

  thin packing material.

  Finally, it should be noted that the means for guiding in translation, the deployment springs of the mobile part, the retaining means, the triggering means and the non-return means, as well as the resetting means, may be replaced by means equivalent to those shown and described by way of examples

illustrative and not limiting.

Claims (9)

  1-Active headrest for a rolling vehicle seat, comprising a bearing surface for the head of the seat occupant, means for connecting the headrest to the seat back so that said surface support is movable between a rear position and a front position, and actuating means for bringing said support surface from said rear position to said front position, characterized in that it comprises a fixed rear part (2) intended to be connected to the seat back and a front part (3) which defines said bearing surface and is movable in translation forward   relative to the fixed part under the effect of the actuating means (5).   2-headrest according to claim 1, characterized in that   that the fixed part (2) and the mobile part (3) comprise means (4) for guiding in horizontal translation the mobile part on the fixed part.   3-headrest according to claim 2, characterized in that   that the means (4) for guiding in translation are telescopic.   4-headrest according to claim 1, characterized in that the actuating means comprise at least one spring (5) 20 which, in the rear position of the movable part (3), is prestressed and biases the movable part towards the front position, retaining means (6) to hold the movable part (3) in the rear position and controlled release means (10) to release the means retainer (6).   5-headrest according to claim 4, characterized in that   that the spring comprises a mechanical spring (4).   6-headrest according to claims 3 and 4, characterized by   the fact that the spring is a helical compression spring (5)   incorporated in the telescopic guide means (4).   7-headrest according to claim 4, characterized in that the triggering means comprise an actuator electric (10).   8-headrest according to any one of claims   previous, characterized in that it further comprises a system   non-return (12) which blocks the mobile part (3) in the front position.   9-headrest according to claim 8, characterized in that the non-return system (12) comprises a ratchet system (13, 14, , 16).   -Headrest according to claim 9, characterized in that it comprises a rearming system (17) to suppress the action of the non-return system (12) and allow the mobile part 10 (3) of the forward position to the rear position and retain it at the rear position.