WO1998025792A1

WO1998025792A1 - Device for securely adjusting the height of a headrest, in particular for a motor vehicle seat

Info

Publication number: WO1998025792A1
Application number: PCT/FR1997/002272
Authority: WO
Inventors: Olivier Delage; Damien Patte
Original assignee: Centre D'etudes Et Recherche Pour L'automobile (Cera)
Priority date: 1996-12-11
Filing date: 1997-12-11
Publication date: 1998-06-18
Also published as: FR2756789A1; AU5488598A; FR2756789B1

Abstract

The invention concerns a device for securely adjusting the height of a headrest, in particular for a motor vehicle seat, said headrest comprising at least a spindle engaged inside a sleeve (1; 30) integral with the structure (2) of said seat. The invention is characterised in that it comprises at least a ring (3; 32) provided in a housing (12) of said sleeve and arranged for receiving and clamping said spindle, said ring and said housing having cam surfaces (15, 17, 18, 19) co-operating so that the ring selectively tightens or loosens said spindle when said ring is subjected, by means of said spindle, to predetermined direction stresses.

Description

DEVICE FOR LOCKING HEIGHT OF A HEADREST, PARTICULARLY FOR A MOTOR VEHICLE SEAT

The present invention relates to a device for blocking the height of a headrest, in particular for the seat of a motor vehicle, and more particularly to such a headrest of the type comprising at least one pin engaged in a socket integral with the structure of said structure. seat

The head restraints used in the automotive industry comprise, in a known manner, a support cushion mounted at the upper end of two pins, the other end of which enters the seat back When these head restraints are adjustable in height, the pins are generally slidably mounted in sockets integral with the seat frame These pins then have locking notches cooperating with retractable fingers controllable by the user to block the headrest in height in one of a number possible positions

The headrests of motor vehicles obviously have the function of providing comfort to passengers, but even more so of ensuring their safety. In fact, during an impact from the rear of the vehicle, the user's trunk is violently plate against the back of the seat so that in the absence of a headrest his head is suddenly thrown back II frequently results in lesions up to the rupture of the cervical vertebrae

In addition, during frontal impacts, the head restraints tend to rise under the effect of the centrifugal force induced by the rapid tilting of the seat backs to the front. This effect can go as far as ejecting the head restraints

Finally, in the event of chain collisions, a front impact is often followed by a rear impact. The various effects mentioned above are then cumulated

However, this safety function can only be adequately fulfilled if the headrest is sufficiently high or, more generally, is and remains in its optimal adjustment position, or if this position becomes optimal. The difficulty lies in the fact that, if it is a little too low, the user's head goes, striking it from front to back and slightly up and down, push it towards the seatback and thus make it ineffective It is therefore important that the pins of the headrest are firmly held in their mounting sockets when they receive a sudden force upwards or low Furthermore, and to return to the comfort function of the headrest, it must be easily adjustable in height In particular, it is desirable that the user does not have to exert an adjustment effort as important as that which is necessary to depress the headrest by a shock exerted from top to bottom, or in general as that which the headrest must resist in the event of a collision in order not to be out of adjustment

Finally, it must be taken into account that, for reasons of symmetry of the forces and in order to avoid jamming of the headrest when it is adjusted in height, the user must when seated on the seat , make this adjustment using both hands This makes any system requiring the use of an adjustment device such as a button or a rotary knob particularly unsuitable

The present invention aims to overcome these drawbacks. More particularly, the invention aims to provide a device for mounting and blocking the height of a headrest, in particular of the seat of a motor vehicle, which allows effective blocking in particular during a shock exerted from top to bottom, while allowing easy adjustment, without significant effort and by a user installed on the seat

To this end, the subject of the invention is a device for blocking the height of a headrest of a seat, in particular of a motor vehicle, said headrest comprising at least one pin engaged in a socket integral with the structure of said seat, characterized by the fact that it comprises at least one ring disposed in a housing of said socket and arranged to receive and tighten said pin, said ring and said housing having surfaces of cooperating cams so that the ring selectively tightens or releases said pin when said ring is subjected, via said pin, to predetermined directional forces

By adopting surfaces of suitable shape, it is thus possible to cause a tightening of the spindle when a force is exerted on the headrest from top to bottom and / or front to back during an impact, and / or cause the spindle to loosen when a predetermined force is exerted on the headrest from back to front by the user who wishes to adjust it, and / or also to cause a tightening of the spindle under a violent force exerted from the rear towards the front due to the inertia generated during frontal impacts

In particular, said cam surfaces can be arranged to control the tightening of the spindle by the ring as a function of a force exerted from top to bottom on the spindle

In this case, said ring and said housing may include complementary cam surfaces arranged to cause loosening of the spindle by a substantially horizontal steering force, after tightening caused by the action of a force exerted substantially vertically.

Such an arrangement prevents any jamming which could prevent a return to the initial arrangements after a force exerted sufficiently violently in a vertical direction.

In general, we can provide limited agencies resistance means to yield and allow a tightening of the spindle by the ring in the event of effort greater than a predetermined value

Thus, the means according to the invention only come into play in the event of a shock sufficiently violent to justify a blocking of the headrest, that is to say for efforts much greater than those likely to be exercised by a user wishing to adjust it

More particularly, said ring can be split substantially along at least one of its generatrices, and a part of said surface of said housing can be substantially frustoconical flared upward and arranged to cooperate with a part also substantially frustoconical of the surface of said ring for tightening said ring when the latter is subjected to a force exerted from top to bottom

A shock exerted from top to bottom on the headrest thus causes the cone of the ring to sink into that of the bushing and consequently to tighten the ring. In a particular embodiment of the invention, said ring is substantially cylindrical with a substantially vertical axis, said housing also being substantially cylindrical with a substantially vertical axis but elongated from front to rear of the seat, so that the ring can move back and forth in said housing when forces are exerted on it. from these directions, the ring and its housing being shaped so that such displacements cause said spindle to tighten or loosen

Such an arrangement allows both increased security and easy use of the headrest of the invention. According to a particular embodiment of the invention, said ring is split substantially along at least one of its generatrices. and said housing is correspondingly opened said ring having a wing at least on one side of its slot, engaged in the opening of said housing said wing having a surface cooperating with a surface of the opening of said housing for more or less tighten the ring on said spindle according to the position of the ring in its housing

It will be understood that the surface of the wing cooperating with that of the housing can cause a more or less significant tightening of the ring, depending on the forces exerted on the ring by the pin of the headrest. Advantageously, the device according to the invention comprises return means arranged to exert on said spindle a force directed substantially from front to rear

It is thus possible, when a user pulls the headrest forwards to adjust it, to bring it backwards to its normal operating position, and this automatically. This normal, stable operating position, can be adjusted either so as to ensure a locking of the spindle, this blocking only increasing during an impact or so as to allow a sliding, the spindle only blocking during a cnoc In a mode of particular embodiment, said return means comprise a retaining plug mounted on said bushing and traversed by said pin, said plug having an elastic cut pressing the pin towards the rear

In another particular embodiment, said return means comprise a return washer traversed by said pin, and elastic means arranged to press said washer backwards

More particularly, said elastic means may comprise at least one elastic tab connecting said washer to said socket

Advantageously, however, said elastic means comprise at least one U-shaped spring, the ends of the branches of which are fixed to said washer, the branches of which extend downwards generally in the direction of the axis of the spindle while bearing on the structure of the seat, and the central part of which bears on said spindle

In this case, said spindle preferably has, near its end, a notch arranged to receive said central part, release means being provided for pushing said central part out of said notch

This arrangement provides, in addition to the desired force forwards on the spindle, an anti-extraction means making it possible to prevent the extraction of the headrest from the seat when it is pulled too abruptly upwards by the occupying the seat or during violent frontal impacts When the spindle is about to arrive at the end of its travel, the central part of the U-shaped spring engages in the notch, blocking this travel or according to the embodiment forming a notch sensitive to the user In the event of the stroke being blocked, said release means advantageously comprise an actuatable pusher, in particular through the seat trim, from the rear or the front of the latter, arranged to push on said branches U-shaped spring

It is thus always possible to dismantle the headrest at least for a user knowing where the pusher is located under the seat trim

In a particular embodiment, said pusher is connected elastically to the socket and comprises means for snapping the socket onto the structure of the seat

Thus in this embodiment the pusher allows both the disassembly of the headrest and that of its support sleeve

Also in a particular embodiment, said pusher is connected by αes elastic uprights to a housing block of said ring

It is preferably provided that said pusher comprises a lug arranged to come into abutment on said spindle when the pusher is actuated and that said spindle is in place, so as to prevent opening of the socket as long as the spindle is engaged in the socket

We will now describe, by way of nonlimiting example, particular embodiments of the invention, with reference to the appended schematic drawings in which FIG. 1 is an exploded perspective view of a device according to the invention arranged for mounting a headrest on the back of a seat, in particular of a motor vehicle,

- Figure 2 is a partial view in axial section of the socket of this device

FIG. 3 is a sectional view along the line III-III of FIG. 2,

- Figure 4 is a view on a larger scale, in axial section, of the aforementioned ring disposed in its housing in the normal operating position, - Figure 5 is a view similar to that of Figure 4, when the support- head receives a shock from top to bottom,

- Figure 6 is a cross-sectional view of the device according to the invention in the normal operating position

FIG. 7 is a view similar to that of FIG. 6 when the headrest is pulled towards the front of the vehicle,

FIG. 8 is a view similar to that of FIGS. 6 and 7 when the headrest is subjected to an impact from the front of the vehicle towards the rear,

FIG. 9 is a perspective view of a device according to another embodiment of the invention, FIG. 10 is a partial side view illustrating the operation of the device of FIG. 9,

- Figures 1 1 to 13 illustrate, in cross section of the variants of the ring shown in Figure 6, and

- Figures 14a and 14b are schematic axial sectional views illustrating the operation of another embodiment of the invention

As shown in Figure 1, the device according to the invention generally comprises a socket 1 arranged to be received in any suitable manner by the frame 2 of the seat back of a motor vehicle A ring 3 is provided for be placed in a housing of the socket 1, and a retaining plug 4 is mounted on the socket 1, at its upper part

It will first be observed that the socket 1 is represented in FIG. 1 only by its internal surfaces. Only the latter are indeed of importance with regard to the invention, the external forms of the socket depending only on its attachment to the frame In addition, the seat frame is here represented in the form of a U-shaped profile, but it could just as easily be formed of tubes

The sleeve 1 is formed, from bottom to top, of an attachment part 10 to the structure 2 of the seat, of a tubular part 1 1 for guiding the headrest pins, of a ring housing 12 , and a part 13 for connection to the structure of the seat, unrelated to the invention The housing 12 comprises a substantially cylindrical part 14 terminated downwards by a frustoconical surface 15 flared upwards capable of forming a cam Furthermore, the housing 12 is open towards the front in its lateral surface along a generator to form an elongated opening 16 parallel to the general axis of the device The surfaces 17 of the edge of the opening 16 form a dihedral whose edge is itself parallel to this axis and the planes of which also form a cam, as will be seen below. Finally, the housing 12 is, transversely to its longitudinal direction, substantially cylindrical with an elongated base The opening 16 is formed at one of the ends of the housing 12 away from its axis

The ring 3 is substantially cylindrical. It comprises, in its part corresponding to the cam surface 1 5, another external cam surface 18 which is also tapered, flared upwards. It is furthermore split along one of its generatrices. from the slot, separated at rest being extended by two wings 19 which, when the ring is in its housing, come to bear against the surfaces 17 of the socket. The retaining plug 4 is arranged externally in a suitable manner to be fixed to the upper part. of the socket 1 Its internal surface is substantially cylindrical and its side wall forms an elastic cut 20 projecting inwards

When the assembly which has just been described is mounted, the bush 1 is fixed to the frame 2 with the opening 16 of the housing 12 directed towards the front of the vehicle The ring 3 is placed in its housing 12 and the plug 4 is mounted on the socket 1 so that the cutout is located on the side of the front of the vehicle Finally, the headrest support pin, not shown, is engaged in the socket 1 and passes through the ring 3 and the bushing 4 The ring 3 tightens the spindle and the cutout 20 of the plug 4 pushes it backwards In the normal position, the forces are balanced, in particular those exerted by the wings 19 on the surfaces 17 and those exerted by the cutout 20 on the spindle, so that so that the ring 3 is located, transversely, in its housing 12, in a central position relative to the front and rear of the vehicle Vertically, the ring 3 is in a position such that the surfaces 15 and 18 are not completely in contact.

When a force is exerted vertically from top to bottom on the headrest, the spindle drives the ring 3 downwards, as shown in FIG. 5. In this movement, the cam surface 18 comes into contact with the surface cam 15 on which it is pressed. The ring 3 thus tends to close and tighten the spindle all the more strongly, and thus to prevent it from sinking into the socket 1.

When the user, for example seated in his seat, grasps the headrest with two hands behind his neck and pulls it forward as shown in Figure 7 the spindle drives the ring 3 forward so that wings

19, having more room in the dihedral flared towards the front of the surfaces 17, moves away and the ring 3 opens. It thus loosens the spindle that the user can easily slide up or down.

It will be noted HERE, which will be of importance in relation to FIGS. 14, that an even more vigorous effort exerted towards the front, in particular in the event of a frontal impact, again causes the spindle to tighten by the ring 3 Indeed , the converging front surfaces of the housing 12 and the wings 19 then tend to cause a reduction in the diameter of the ring when, after being brought into contact, they persist in being forced to bear against each other.

When, finally, a shock is exerted on the headrest from front to rear, the spindle drives the ring 3 towards the rear of the housing 12, as shown in FIG. 8. In this movement, the wings 19 are tightened by the cam surfaces 17, so that the ring 3 tends to close and tighten the spindle, thus blocking any vertical movement of the latter

The invention therefore makes it possible, on the one hand, to block the headrest in the event of an impact directed from top to bottom. on the other hand to also block it in the event of an impact directed from the front to the rear, and finally to unlock it by a traction exerted from the rear to the front. It will however be observed that these three actions, although exercised in a complementary manner by the same bodies. are independent and therefore the invention is not limited to their combination

Figures 9 and 10 show another embodiment in which the sleeve 30 is limited to a housing block 31 for a ring 32, the block 31 supporting on the one hand, downwards, locking members 33, and d on the other hand, upwards, a return washer 34. The block 31 and the ring 32 are of the same type and operate in the same way as the housing 12 and the ring 3 and will therefore not be described in more detail.

The locking members 33 include a U-shaped spring 35 and a pusher 36

The pusher 36 is essentially constituted by a plate connecting the free ends of two elastic uprights 37 The elastic uprights 37 have their other end connected to the block 31, and they extend downwards from this block, they can in particular be molded in one piece with the block 31 The pusher 36 protrudes towards the rear of the vehicle relative to the uprights 37

The return washer 34, which can moreover be a sleeve, or part of a washer or sleeve, or even a support pad, is HERE mounted on the block 31 by means of three elastic tabs 38. The legs 38 and the washer 34 are advantageously molded in one piece with the block 31 and, where appropriate, with the uprights 37 and the pusher 36

The washer 34 also carries two bosses 39 which receive the free ends of the branches of the U-shaped spring 35 These branches then curl downward, each to form a very flared V whose top 40 is directed towards the front of the vehicle and which is located in front of the uprights 37. The lower parts 41 of the Vs are therefore directed towards the bottom and towards the rear of the vehicle. These parts 41 have their lower ends facing the uprights 37 so that, when the push-button 36 is pressed, there is a tendency to open the V formed by the branches of the U. The lower ends of the branches of the U-shaped spring 35 are themselves connected by a substantially horizontal U, open towards the rear, whose central part 42 therefore forms the central part of the U-shaped spring 35. The central part 42 is therefore located substantially below the aforementioned vertices 40 The assembly which has just been described is housed in a sheath 43 for example a tube, ground seat structure idary The headrest is put in place by engaging each of its pins

44 in the return washer 34, then in the ring 32, and finally between the pusher 36 and the central part 42 of the spring 35 The vertices 40 of the V formed by each branch of the U-shaped spring 35 then come, in this position, into support on the front walls of the ducts 43

Thus when the headrest is in place, the upper parts of the branches of the springs 35 exert on the washers 34, and therefore on the pins 44, a force directed towards the rear of the vehicle, by reaction of the tops 40 on the sheaths 43 This effort is balanced as in the embodiment described above with those exerted in particular by the ring 32

The elastic tabs 38 (not shown in FIG. 10, as well as the block 31), also preferably exert, in this position, an effort directed in the same direction However, this effort could be negligible Conversely if this effort is sufficiently significant and constant over time, the spring 35 can be omitted, in which case it will not perform the function which will now be described.

The spindle 44 has, at its lower end, a notch 45 parallel to the central part 42 of the spring and on the side of this part. The notch 45 has a steep side downwards and a side inclined upwards. The lower end of pin 44 is rounded or tapered or tapered

Thus, when the headrest is pushed in to be put in place, the lower end of the pins 44 pushes forward the lower parts of the springs 35 The central parts 42 of these springs slide along the surface of these pins , engage in the notches 45, then emerge from them due to the surfaces inclined upwards of the latter

When, on the contrary, an attempt is made to abruptly extract the headrest, voluntarily or not, the central parts 42 engage in the notches 45, but cannot come out of it because of the abrupt side which they present downwards It is then necessary to press the pusher 36 to deform the spring 35, release it from the notch 45, and thus authorize the extraction of the headrest

A notch with inclined sides both at the top and at the bottom would allow the headrest to be extracted without any special operation, but would indicate to the user when lifting the headrest that he is approaching from the maximum high point We will also observe that a set of such notches on the pins allows the part 42 of the spring to be used as a positioning finger for the headrest

The pusher 36 protrudes towards the rear of the vehicle so that, when the sleeve 30 is in place, it protrudes from the lower end of the sheath 43 Thus, it snaps onto this sheath during its mounting II is therefore possible to disassemble the socket 30 by pushing in the plunger 36 after removing the headrest

Finally, it will be observed that a lug 46 projects from the pusher 36 substantially in the middle of the side of the part 42 of the spring. When an attempt is made to actuate the pusher while the pin 44 is in place, the lug abuts on the spindle and thus prevents the pusher from disengaging from the sheath 43 It is thus not possible to disengage the socket 30 without having previously removed the headrest Likewise, it is impossible to introduce the pins of the '' headrest in a sheath badly clipped in its socket

Of course, the forms of cams described so far are in no way limiting. By way of example, FIGS. 1 1 to 13 show three forms of rings and of corresponding housings which may be suitable.

In the embodiment of FIG. 11 the wings 47 are, not diverging towards the outside as described with reference to FIG. 6, but converging, the housing 48 being HERE open towards the rear at 49 The operation is therefore reverse, compared to the front and rear of the vehicle of what has been described above

The housing 48 is further HERE decreased in cross section forwards at 50, so that a displacement both forwards and backwards of the headrest causes the pin to lock In all case, of course, the various shapes can be reversed from front to back depending on whether one wishes to obtain a blockage in the event of an impact from either side

Figures 12 and 13 show cases of operation similar to that of Figure 1 1 The wings 51, and respectively 52, are here in the form of a dihedral cooperating with cam surfaces of corresponding shape of the housing 48 A movement of the pins is towards the front be towards the rear therefore causes them to be tightened, these pins being in equilibrium in the position shown

In FIGS. 14, the frustoconical axial cams 15.18 are replaced by V-shaped cams 53.54 This embodiment has two other particular characteristics

Firstly, a front (or rear as the case may be) stop 55, of the housing has a limited resistance, HERE due to a reduced thickness A normal effort of the user causing a sliding until the front contact of the external surfaces of the ring and interior of the housing, may thus have only an opening result of the ring, as described with reference to FIG. 7 On the other hand, a greater force causing the abutment 55 to rupture, will allow movement even more towards the front of the ring again causing the spindle to tighten

The ring and the housing moreover have here inclined surfaces upwards and forwards 56 and 57 respectively opposite one another

When a force has been exerted downwards on the headrest and the latter is blocked by the different surfaces of cooperating cams, it may be unable to return to its high position When the headrest is then pulled forward by a maneuver by the user, the ring is driven upwards by the cooperation of the cam surfaces 56 and 57, causing the headrest to be released

Claims

1 - Device for blocking the height of a headrest of a seat, in particular of a motor vehicle, said headrest comprising at least one spindle engaged in a socket (1; 30) integral with the structure (2) of said seat, characterized by the fact that it comprises at least one ring (3; 32) disposed in a housing (12) of said socket and arranged to receive and tighten said pin, said ring and said housing having cam surfaces (15,17, 18,19) cooperating so that the ring selectively tightens or releases said pin when said ring is subjected via said pin to forces of predetermined direction

2- Device according to claim 1, wherein said cam surfaces are arranged to control the tightening of the spindle by the ring according to a force exerted from top to bottom on the spindle

3- Device according to any one of claims 1 and 2, wherein said ring is split substantially along at least one of its generatrices, and a part (15) of said surface of said housing is substantially frustoconical flared upwards and is arranged to cooperate with a part (18) also substantially frustoconical of the surface of said ring to tighten said ring when the latter is subjected to a force exerted from top to bottom

4- Device according to any one of claims 1 to 3, wherein said ring is substantially cylindrical with substantially vertical axis, said housing also being substantially cylindrical with substantially vertical axis but elongated from front to rear of the seat, so that the ring can move back and forth in said housing when forces are exerted on it in one of these directions, the ring and its housing being in conformity so that such movements cause a tightening or a loosening of said spindle

5- Device according to any one of claims 1 to 4, wherein said ring is split substantially along at least one of its generatrices and said housing is opened in a corresponding manner, said ring having at least one wing (19) on one side of its slot engaged in the opening of said housing, said wing having a surface cooperating with a surface (17) of the opening of said housing to more or less tighten the ring on said spindle depending on the position of the ring in its housing

6- Device according to any one of claims 1 to 5, comprising return means (20) agencies to exert on said spindle a force directed substantially from the front to the rear

7- Device according to claim 6, wherein said return means comprise a holding plug (4) mounted on said socket and traversed by said pin, said plug having an elastic cutout (20) pressing the pin backwards

8- Device according to claim 6, wherein said return means comprise a return washer (34) through which said pin, and elastic means (35, 38) agencies to press said washer backwards 9- Device according to the claim 8 wherein said elastic means comprise at least one elastic tab (38) connecting said washer to said socket

10- Device according to any one of claims 8 and 9, wherein said elastic means comprise at least one U-shaped spring (35) whose ends of the branches are fixed to said washer, whose branches generally extend downward in the direction of the spindle axis by resting on the seat structure and the central part (42) of which rests on said spindle

1 1 - Device according to claim 10 wherein said pin comprises, near its end, a notch (45) arranged to receive said central part, release means (36) being provided for pushing said central part out of said notch

12- Device according to claim 1 1, wherein said release means comprise an actuatable pusher, in particular through the seat trim, from the rear or the front thereof, arranged to push on said branches of the U-shaped spring

13- Device according to claim 12, wherein said pusher is connected elastically to the socket and comprises means for latching the socket on the seat structure 14- Device according to claim 13, wherein said pusher is connected by elastic uprights (37) to a block (31) for housing said ring (32)

15- Device according to any one of claims 13 and 14, wherein said pusher comprises a lug (46) arranged to abut on said pin when the pusher is actuated and that said pin is in place, so as to prevent the unlatching of the socket as long as the spindle is engaged in the socket

16- Device according to claim 2, wherein said ring and said housing comprise complementary cam surfaces (56, 57) arranged to cause loosening of the spindle by a substantially horizontal steering force, after tightening caused by the action of a force exerted substantially vertically

17- Device according to any one of claims 1 to 16, comprising means (55) of limited resistance arranged to yield and allow a tightening of the spindle by the ring in the event of a force greater than a predetermined value