FR2943957A1 - Motor vehicle seat, has oblong shaped slots arranged in such manner that displacement of fixation units in respective slots from front direction towards backward direction causes pivoting of backrest towards front direction - Google Patents

Abstract

The seat has a backrest (2) connected to a base (1) by connection units. The connection units include a separability flange (3) directly connected to the base and a flange (22) of the backrest by fixation units (51, 52) and passing into respective oblong shaped slots (31, 32) formed in the flange of the backrest. The slots are arranged in such a manner that displacement of the fixation units in the respective slots from a front direction towards a backward direction causes pivoting of the backrest towards the front direction.

Description

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Motor vehicle seat with controlled movement of the backrest in the event of a rear impact.

The present invention relates to a motor vehicle seat with controlled movement of the backrest in the event of a rear impact on the vehicle. Already known, for example by EP-0850155, such seats, whose backrest is mounted on the seat so as to be able to move during such a rear impact, to dampen the effects on the body of passengers. Indeed, it is well known that in case of rear impact on a motor vehicle, passengers may suffer severe bodily injury, as is also well explained in the aforementioned document. A major risk is that, in current use, the head and neck of the occupant of the seat do not rest on the backrest or the headrest. As a result, in the event of a rear impact, the head tends to move back sharply when pivoting relative to the body, which remains substantially immobile with respect to the seat, the back of the occupant being held against the backrest. The neck of the person is thus subjected to efforts that can lead to rupture of ligaments. After this initial phase during the shock, the head of the occupant tends to start sharply forward, by rebound on the headrest, and the neck then undergoes a strong bending in the opposite direction, even more detrimental to the occupant of the seat.

Thus, it is understood that it is desirable, to avoid or at least limit these disadvantages, on the one hand to avoid excessive movement of the head backwards in the first phase of the shock, then to avoid the possible reverse movement in the second phase. The seat described in the aforementioned document EP08500155 comprises for this purpose a double link articulated between the backrest and the seat. More specifically, the file is mounted articulated in a current manner on a

2 lower flange, this first joint allowing adjustment in conventional inclination of the backrest. In addition, said lower flange is mounted on the seat by a set of rods arranged so that, under the effect of a recoil force applied to the bottom of the backrest, such as the force exerted by the passenger's pelvis in case of rear shock, the said flange moves relative to the seat in a combined movement of recoil and pivoting in one direction leading to a relative pivoting forward of the top of the folder, then rigidly connected to the flange. The kinematics of the set of rods is determined so that the relative pivoting of the backrest results in an actual forward movement of the upper part of the backrest relative to the seat. As a result, during a rear impact, the head of the occupant of the seat is more quickly held by the top of the backrest or the headrest, which therefore limits the risk of injury incurred in the first phase of the shock. In the second phase, it is then the backrest which can pivot backwards relative to the lower flanges, according to its usual articulation used for tilting adjustment, this pivoting accompanying the overall displacement of the trunk and the head of the the occupant backwards. This pivoting of the backrest is braked and cushioned to prevent movement too fast and ensure a deceleration as smooth as possible of the body of the occupant, and especially avoid the effect of bounce of the head forward. Such a configuration is, however, quite complex, in particular because the displacement required during the first phase is managed by the articulated link link between the lower flange and the seat, and by the tilt adjustment connection of the backrest during the second phase. phase, which therefore requires successively controlling two independent movements.

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In addition, because the link rods between the lower flanges and the seat is located at a low level, it follows that the torques and forces exerted on these links are even more important than they are far the point of application of the great force applied to the backrest by the back of the user in case of shock.

The present invention aims in particular to solve the problems mentioned above, and more generally aims to provide a new seat, simpler to achieve and simpler operation and more effective in case of rear impact.

With these objectives in view, the invention relates to a motor vehicle seat with controlled movement of the backrest in the event of a rear impact on the vehicle, wherein the backrest is connected to the seat by connecting means arranged to cause a forward movement of the upper part of the backrest when the lower part of the backrest is moved backwards relative to the seat under the effect of a force directed towards the rear, exerted on this lower part.

According to the invention, the seat is characterized in that said connecting means comprise, on each side of the seat, a separability flange directly connected to the seat and connected to a back flange by a first and a second fixing member rigidly connected to the back flange and passing into respective first and second slots of generally oblong shape, formed in the separability flange, the said first and second oblong-shaped lights being oriented so that a displacement of the fastening members in their respective lights from the front

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backward, cause the backrest to pivot forward. Thus, as will be understood better later, when the trunk of the seat passenger is strongly pushed against the backrest, in the event of a rear impact on the vehicle, the backrest recoils under this force, being guided by the sliding fasteners then in the oblong slots, and the relative orientations of said lights, with the rear light inclined upwards or the front light directed downwards, cause, simultaneously with the recoil of the lower part of the backrest, a pivoting thereof towards forward. The relative inclination of the two lights, which thus serve as a guide for each fastener respectively, is determined so that, despite the recoil of the bottom of the backrest, the backrest has a real forward movement, which allows the donation of hold the head of the occupant of the seat and avoid the neck to undergo a strong bending backwards.

The fasteners are preferably rigidly fixed pegs, for example riveted, on the lateral flange of the backrest frame and having a head ensuring the retention flange against the flange of the backrest, in the transverse direction of the seat. Typically, the two fasteners are located substantially on the same horizontal level, the first light, located foremost, extending substantially perpendicular to the general plane of the backrest, in the position of current use, and therefore substantially horizontal , and the second light having its front end substantially in the extension of the first light and having a first portion, at the front, inclined upwards towards the rear.

According to a preferred arrangement, the second light, located towards the rear, is extended, at the rear, by a rear part oriented downwards. Thus, after the backrest has swiveled forward as previously indicated, and the inertia force exerted by the seat user continuing to apply to the backrest, the backrest pivots backward and downwardly. around the axis of the first hinge member which remains housed in the front slot, the second hinge member then sliding in said rear portion of the rear light downwardly. Thus, the backrest allows, after having participated in maintaining the head of the occupant of the seat, to dampen the movement thereof backward with respect to the seat, and thus avoids, or the month limits, the rebound effect of the head that would occur if the upper part of the backrest and the headrest remained too rigidly fixed. The threshold of effort triggering the beginning of sliding fasteners, such as the aforementioned pins, in the lights is determined by retaining elements holding fasteners fastened to respective front ends of their lights current use of the seat. Such retaining elements may preferably be made in the form of braces formed in the separability flange, connecting the edges of the lights just behind the front position of the pins. These straps are shaped to break from a predetermined force, and then deform the passage of the pins when they slide backwards in the lights. The resistance to deformation of these straps after the initial rupture generates a restraining force which slows down the movement of the pins and dampens the overall movement of the backrest. Similar damping means can be used also between the front part and the rear part of the lights, to brake and damp the pivoting of the

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backrest in the second part of its movement in case of shock. Typically, the separability flange is a hinge flange, pivotally mounted and adjustable in inclination directly on the seat, in a manner known per se to allow adjustment of the inclination of the backrest. It will be noted that, in comparison with the aforementioned prior art, the fact that the means for guiding and damping the displacement of the backrest in the event of a rear impact are situated above this articulation is particularly favorable, since this limits the forces in Indeed, the constraints to be supported by the file retention members in current use are less than if these bodies are located lower, the torque exerted on these organs by the record is lower. In addition, in the system according to the invention, the current articulation mechanism of the backrest is not used as a rear pivot axis during the second phase of the displacement, and it is therefore not necessary to provide means. specific restraint and damping in connection with this articulation mechanism.

Other features and advantages will appear in the description which will be given by way of example of an automobile seat according to the invention.

Reference is made to the accompanying drawings in which: - Figure 1 is a side view of the frame of the seat, in the position of current use, - Figure la is a detail view of Figure 1, - Figure 2 is a detail view of the lower end of the backrest flange,

7 - Figure 3 shows, in rear view, the connection between the separability flange and the seat flange, - Figure 4 is a view corresponding to that of Figure 1, when the backrest pivots to the before during the first phase of movement in the event of a rear impact, FIG. 4a is a view of detail A of FIG. 4, FIG. 5 is a view corresponding to that of FIG. 1, when the backrest pivots towards the rear. a rear view during the second phase of movement in the event of a rear impact; FIG. 5a is a view of detail A of FIG. 5; FIG. 6 illustrates a preferred embodiment of the guide lights in the separability flange, FIG. 7 is a view on a larger scale of the front light in this embodiment, FIG. 8 is a sectional view along the line VIII - VIII of FIG. 7, FIG. 9 is a view corresponding to FIG. that of Figure la, in a specific embodiment using a cushioned element Figure 10 is a view corresponding to that of Figure 5a in this specific embodiment.

The seat according to the invention, shown in Figure 1 comprises a seat 1 and a backrest 2 provided with a headrest 21. The backrest comprises, on each side, an armature flange 22 on the lower portion 221 which is fixed, in a manner that will be described in detail later, a separability flange 3 which is connected to a flange 11 of the seat frame 1 by a hinge mechanism 4, of a type known per se for adjusting the inclination of the backrest relative to

8 the seat. The articulation mechanisms 4 located on each side of the seat are connected by a connecting bar 41 which passes through the holes 222 provided for this purpose in the lower part 221 of the flanges 22 of the backrest (see Figures 2 and 3).

The connection between the separability flange 3 and the flange 22 of the backrest is provided by connecting members preferably consisting of pins 51, 52 riveted to the flange 22 of the file and passing through slots 31, 32, respectively, cut in the flange separability. As can be seen in FIG. 8, the pins comprise a head 511 which ensures the lateral retention of the separability flange 3 against the backrest flange 22.

The pin 51 situated furthest forward of the front seat is housed in a front slot 31 which extends, for example over a length of the order of 20 mm, substantially horizontally when the backrest is in its position of use. current, shown in Figure 1. The pin 52, located further towards the rear of the seat, is housed in a rear light 32 which has its front end substantially in the extension of the front light and which has a first portion 321, to the before, of a length substantially equal to that of the front light, and inclined upwards towards the rear, with a slope, with respect to the direction of the front light, of the order of 15% for example. The rear light 32 is extended, at the rear, by a rear portion 322 facing downwards and also extending over a length of the order of 20 mm for example. The lights 31 and 32 are shaped so that, in the position of current use of the seat, that is to say, as long as there is no significant rear impact on the vehicle, the pins 51 and 52 are

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rigidly held at the front ends of their respective lights, as illustrated in FIGS. 1 and 1a, by retaining elements. A preferred embodiment of the lights and retaining elements, to ensure this maintenance, is illustrated in Figures 6 to 8. We will describe this embodiment for the front light 31, illustrated particularly in Figure 7, the same embodiment being used for the front portion 321 of the rear light 32. In this embodiment, the retaining elements are straps 33 which extend from each edge, lower and upper, of the light 31 and meet at the the median line of the light, thus forming a circular hole 311 whose turn is closed by said straps, and in which the pin 51 is housed, as can be seen in Figure 8. A notch 34 is formed at the junction straps 33, to form a breakout primer, allowing the shoulder straps to deviate when a large force is exerted by the pin 51 on these straps, in case of rear impact causing a strong pous The dimensions of the shoulder straps and their connecting zone, at the notch 34, are determined in such a way that the break occurs for a predetermined threshold of said pushing force. When the force exerted on the backrest exceeds this threshold, the connection of the straps at the notch 34 breaks under the force exerted by the pin 51. The straps are then deformed plastically by pivoting according to the arrows F of FIG. until it is accommodated in recesses 35 formed for this purpose in the upper and lower edges of the aperture 31, so that the peg 51 can slide backwards into said aperture 31. plastic deformation of the shoulder straps helps to slow down the movement

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pawn rearward after breaking the connection between said straps, and thus allows, as will be seen later, to dampen the pivoting of the folder. Similar retaining means are made forward of the front portion 321 of the rear light, and may also be provided at the area 323 between the front portion 321 and the rear portion 322 of the rear light 32.

In connection with Figures 1, 2 and 3, we will now describe the operation of this system during a rear impact on a vehicle equipped with a seat according to the invention. As already indicated, in its position of current use, represented in FIG. 1, the backrest is held rigidly connected with separating flanges 3 by pins 51 and 52, held in abutment before in their respective slots 31, 32 When a rear impact occurs, the inertia of the trunk of the occupant of the seat causes a significant effort exerted by the pelvis of the occupant on the lower part of the backrest, substantially horizontally. This force results in a force exerted by the pins 51, 52, on the straps 33, causing the breaking of their connection and their deformation, as explained above. The pins 51, 52 then slide in their respective slots: the pin 51 moves backwards, substantially horizontally in the slot 31; the pin 52 moves in the front portion 321 of the rear light 32, so backward and upward, as shown in Figures 4 and 4a. Consequently, following the force exerted on the bottom of the backrest according to the arrow F1, the backrest pivots forward, the upper part moving forward according to the arrow F2. Note that the bottom of the backrest can move backwards by 20 mm, depending on the value of the length of the indicated light

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previously as an example, but, because of a pivot corresponding to the inclination of about 15%, the top of the record will move for example more than 100 mm. It will therefore be understood that, as a consequence of this first phase of moving the backrest, the top of the backrest and the headrest will then come into a favorable forward position to hold the head of the occupant. At the end of this first phase, the bottom of the backrest can not move back because the pins 51 and 52 have come into abutment at the rear end respectively of the front light 31 and the front portion 321 of the rear light 32. push F3 on the backrest being then exerted both by the trunk and the head of the occupant of the seat, it follows a pivoting torque around the axis constituted by the front pin 51, which results in a force exerted by the rear pin 52 on the connecting zone 323 between the front portion 321 and the rear portion 322, facing downwards, of the light 32. After breaking of this connecting zone 323, the rear pin 52 can slide in the rear portion 322 of the light, causing a pivoting of the backward and downward folder, as shown by the arrow F4 of Figure 5. It will also be noted that the displacement of the backrest by contribution to separability flanges is made possible thanks to to the existing game, provided sufficiently important for this purpose, between the connecting bar 41 of the hinge mechanisms 4 and the holes 222 of the lower portion 221 of the flanges 22 of the file as seen in Figure 2.

The holes 222 may also not be circular. Their shape and position on the back flanges 22 may be adapted to accept, with sufficient clearance, the different positions of the connecting bar 41 relative to the backrest frame during movement of the backrest relative to separability flanges.

According to a complementary arrangement illustrated in FIGS. 9 and 10, intended to ensure additional damping of the pivoting of the backrest, and to avoid a possible return of the backrest forward in the first phase of its movement, there is provided a deformable part 6, fixed firstly on the back flange 22, for example on one of the pins, and secondly on the separability flange 3. In current use position of the seat, this deformable part links the separability flange and the flange folder, and thus participate in removing any games between these elements. In the event of a rear impact, the plastic deformation provided for this deformable part makes it possible, during the sliding of the backrest, to have a progressive movement of the backrest limiting the severity of the shock of the spine of the occupant on the seat structure. When the lower part of the backrest has receded, the plastic deformation undergone by the deformable part contributes to the retention of the backrest, avoiding a possible reverse movement thereof.

The invention is not limited to the embodiments which have just been described by way of example.

Thus, although it is preferentially the first part of the rear light which is directed upwards, and this same rear light which has a rear part pointing downwards, it could also be envisaged to orient the front light downwards, and a rear portion of this front upward light, such an arrangement being functionally substantially equivalent. Also, the retaining means, and braking and damping means mentioned above are not exclusive and could also be made in other forms, accessible to the skilled person.

Claims (10)

REVENDICATIONS1. Motor vehicle seat, wherein the backrest (2) is connected to the seat (1) by connecting means arranged to cause a displacement towards the front of the upper part of the backrest when the lower part (221) of the backrest is moved rearwardly relative to the seat under the effect of a force (F1), directed rearward, exerted on this lower part, characterized in that said connecting means comprise, on each side of the seat, a separability flange (3) directly connected to the seat and connected to a flange (22) backrest by a first (51) and a second (52) fastener, rigidly connected to the backrest flange and passing through respective first (31) and second (32) slots, of generally oblong shape, formed in the separability flange (3), said first and second oblong-shaped lumens being oriented so that a displacement of the fasteners ( 51,52) in their respective lights s from front to back, cause the backrest to pivot forward. 2. Motor vehicle seat according to claim 1, characterized in that the relative inclination of the two lights (31, 321) is determined so that despite the recoil of the bottom of the folder, the backrest has a real movement towards the before. 3. Motor vehicle seat according to claim 1, characterized in that the fastening members are pins (51,52) fixed on the lateral flange (22) of the backrest frame and having a head (511) ensuring the maintaining the separability flange against the back flange. 14 4. Motor vehicle seat according to claim 1, characterized in that the two fasteners (51,52) are located substantially on the same horizontal level, the first light (31), located foremost, extending substantially perpendicular to the general plane of the backrest in position of current use, and therefore substantially horizontal, and the second lumen (32) having its front end substantially in the extension of the first lumen 10 and having a first portion (321) inclined upwards to the back. Motor vehicle seat according to claim 4, characterized in that the rearward second light (32) is extended rearwardly by a rearward portion (322) facing downwards. 6. Motor vehicle seat according to claim 1, characterized in that the force threshold triggering the start of sliding fasteners (51,52) in the slots (31,32) is determined by elements of retainer (33) holding the fasteners secured at the front ends of their respective slots in routine use of the seat. 7. Motor vehicle seat according to claim 6, characterized in that the retaining elements are shoulder straps (33) formed in the separability flange (3), connecting the edges of the apertures (32, 32) just to the rear of the front position of the pins (51,52), the straps (33) being shaped to break up from a predetermined force, and then deforming as the pieces pass when they slide backwards in the lights . 15 8. Motor vehicle seat according to claim 7, characterized in that the straps (33) extend from each edge, lower and upper, lights (31, 32) and meet at the center line of the lights, thus forming a circular hole (311) whose turn is closed by said straps, and wherein the pins (51, 52) are housed, a notch (34) being formed at the junction of the straps (33) to form a rupture primer, and recesses (35) formed in the upper and lower edges of the apertures (31, 312) for accommodating the straps (33) when plastically deformed by the pins (51, 52) . 9. Motor vehicle seat according to any one of claims 6 to 8, characterized in that it also comprises similar retaining means at the area (323) between the front portion (321) and the rear portion ( 322) of the rear light (32). 10. Motor vehicle seat according to claim 1, characterized in that it comprises a deformable part (6) fixed on the one hand on the backrest flange (22) and on the other hand on the separability flange (3). ), to allow, by plastic deformation, when sliding the folder backwards, a damping of the movement of the file and a retention of the file then, avoiding a reverse movement thereof.