GB2402057A

GB2402057A - A pivotable vehicle headrest activated by an impact sensor

Info

Publication number: GB2402057A
Application number: GB0312304A
Authority: GB
Inventors: Lennart Simonsson
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 2003-05-29
Filing date: 2003-05-29
Publication date: 2004-12-01
Anticipated expiration: 2023-05-29
Also published as: GB0312304D0; GB2402057B

Abstract

A head-rest arrangement is disclosed which is provided on the back-rest (1) of a vehicle seat. The head-rest arrangement comprises a head-rest unit (4) supported by support arms (2,3) for pivotal movement about a substantially horizontal pivot axis (7) which is provided in the region of the top of the back-rest (1). A deflector (9) is mounted within the seat and is supported by a support arm (8) in order to effect pivotal movement about the horizontal axis (7). The support arms (2,3) of the head-rest make a predetermined angle a with the support arm (8) of the deflector, and a mechanism is provided to reduce the angle a in response to a signal from a sensor. The head rest may include a mechanism to part of the front of the head rest in response to a signal from a sensor. A load limiter and or a locking means may be provided to control movement of the support arms.

Description

DESCRIPTION OF INVENTION

"IMPROVEMENTS IN OR RELATING TO A HEAD-REST ARRANGEMENT" THE PRESENT INVENTION relates to a head-rest arrangement, and more particularly relates to a head-rest arrangement for use in a vehicle seat.

It is known that an occupant of a vehicle may, in an accident situation, suffer from "whiplash" injuries. Typically these injuries are caused as a consequence of a relative acceleration between the torso of a seat occupant and the head of the seat occupant.

For example, in a rear impact, the entire chassis of the vehicle that is involved in the impact may be accelerated forwardly over a very brief period of time. The seats in the vehicle will also be accelerated forwardly thus imparting an almost identical acceleration to the buttocks and chest of the seat occupant.

However, no force is directly applied to the head of the seat occupant which has a substantial mass and which thus has a substantial inertia. Thus, effectively, the head of the occupant will remain still whilst the buttocks and chest of the occupant move forwardly with a relatively swift acceleration. This leads to a twisting of the neck which, it is believed, can give rise to very painful "whiplash" injuries.

It has been proposed previously to provide a vehicle seat with a headrest, the head-rest incorporating a mechanism within it which serves to move at least the front face of the head-rest forwards when a rear impact is sensed, with the aim of engaging the rear part of the head of the occupant with the head-rest before there is any substantial movement between the buttocks and chest of the occupant and the head of the occupant. In this way the head of the occupant can be accelerated forwardly at the same time as and at the same rate as the chest, thus meaning that there is no distortion of the neck.

The present invention seeks to provide an improved head-rest for a vehicle seat.

According to the present invention, there is provided a head-rest arrangement provided on the back-rest of a vehicle seat, the head-rest arrangement comprising a head-rest unit supported by one or more support arms for pivotal movement about a substantially horizontal pivot axis provided in the region of the top of the back-rest of the seat, there being a deflector mounted within the seat and supported by at least one support arm to effect pivotal movement about the said horizontal axis, the support arm or arms of the head-rest making a predetermined angle a with the support arm or arms of the deflector, a mechanism being provided to reduce the angle a in response to a signal from a sensor.

Preferably, the head-rest unit incorporates a mechanism to move a front part of the head-rest forwardly in response to a signal from a sensor.

Advantageously, the deflector incorporates a mechanism to move at least part of the front of the deflector forwards in response to a signal from a sensor.

Conveniently, a mechanism is provided to lock the relative position of the support arm or arms of the head-rest and the support arm or arms of the deflector when the angle a has been reduced.

Preferably, the locking mechanism is are associated with a load limiter which enables the angle a to increase, with the absorption of energy, when force levels in excess of a predetermined threshold are experienced.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in 1 5 which: FIGURE 1 is a diagrammatic view of the upper part of the back-rest of a vehicle seat illustrating the head-rest, FIGURE 2 is a diagrammatic view of part of the mount of the head-rest, and FIGURE 3 is an exploded partly cut-away view of part of the mount shown in Figure 2.

Referring initially to Figure 1 of the accompanying drawings, the upper part of a back-rest 1 of a vehicle seat is illustrated. Mounted on the upper part, by means of the two support arms 2, 3, is a head-rest 4. The head-rest 4 may have a separate part 5 defining the front face of the head-rest and, contained within the head-rest may be a mechanism 6 for moving the front part of the head-rest forwardly in response to a sensed rear impact. Various devices of this type have been proposed before.

The two arms 2, 3 are mounted for pivotal movement about a horizontal pivot axis 7 located at the very top of the back-rest. Depending from the pivot axis 7 is a support arm 8, the support arm 8 carrying a deflector 9 mounted in the upper part of the back-rest of the seat. The deflector 9 may simply comprise a deflector plate responsive to an increase in pressure applied to the back-rest of the seat by the upper part of the torso of a seat occupant. However, the deflector 9 is preferably an element which is capable of increasing in size in response to a signal. The deflector 9 may therefore comprise a small air-bag, or similar inflatable unit, or may include an internal spring which is ordinarily compressed, and which is released in response to a signal, the spring then moving a front part of the deflector 9 forwardly, causing the adjacent front part of the back-rest of the vehicle seat to bulge forwardly.

The support arms 2, 3 for the head-rest 4 and the support arm 8 for the i deflector 9 make, in an initial condition of the head-rest, as shown, an angle a.

As will become clear, it is desirable, in an accident situation, especially in a rear impact situation, for the angle a to reduce, and thus the head-rest of the present invention is provided with a mechanism to effect a reduction in the angle a.

As can be seen most clearly from Figure 2, the support arms 2, 3 are each mounted on respective cylindrical housings 10, 11 in alignment with the pivot axis 7. The housings 10, 1 1 are each connected to a central housing 12 by means of a respective intermediate torsion spring unit 13, 14. The central housing 12 is rigidly connected to the upper end of the support arm 8 which carries the deflector 9.

As can be seen most clearly from Figure 3, the central housing 12 is pivotally mounted on a pivot rod 15 which extends from the housing 10 to the housing 1 1 along the pivot axis 7. The pivot rod 15 passes from the housing 1 1 through the torsion spring unit 14. Contained within the torsion spring unit 14 is a torsion spring 16 and also a releasable catch which initially holds the housing 12 in the initial predetermined position. In the embodiment shown, the releasable catch comprises an elongate tube 17 secured to the housing 12 and extending towards the housing 11. A retractable plunger 18 extends from the housing 11, but may be retracted into the housing 11 on receipt of a signal.

When the plunger 18 is retracted into the housing 1 1 it is disconnected from the tube 17, thus permitting the torsion spring 16 to move the central housing 12 rotationally, relative to the housings 10 and 11, in the direction shown by the arrow 19. It is thus to be appreciated that on release of the torsion spring, the angle a will be reduced.

Contained within the central housing 12 may be a ratchet 20 which engages teeth provided on the pivot rod 15, the ratchet 20 serving to prevent the angle or increasing again during the accident.

As mentioned above, the central housing 12 is rotatably mounted on the pivot rod 15 extending between the two end housings 10, 11. However, in a preferred arrangement, the two end housings 10, 11, each of which carry a respective head rest support arm 2, 3 are also rotatably mounted on the pivot rod 15. Thus, after the torsion spring 16 has been released as described above, so as to reduce the angle a, the two support arms 2, 3 carrying the head rest 4, and the support arm 8 carrying the deflector 9 are all free to rotate about the pivot axis 7, with the result that in addition to the reduction of the angle a, backwards pressure applied to the deflector 9 by the torso of the seat occupant in the event of an accident also serves to move the headrest forwardly towards the occupant's head.

It may be beneficial, when the torso of an occupant of the seat moves backwards relative to the back-rest, for the arms 2,3 supporting the headrest to deflect relative to the arm 8 carrying the deflector 9, against the force of the torsion spring, thus absorbing energy. Therefore, the ratchet may be associated with a load limiter, adapted to yield when subjected to a specific predetermined load so that, should a very heavy load be experienced, the angle a may increase, with the absorption of energy, during an accident situation.

Whilst the present invention has been described above with reference to specific embodiments, it is to be appreciated that various modifications can be effected without departing from the scope of the invention. Instead of the above described torsion spring arrangement to reduce the angle a, other alternative arrangement could be utilised. For example, an electric motor or a pyrotechnic charge could be used as part of a mechanism to reduce the angle or.

The motor or pyrotechnic charge being arranged, when activated upon receipt of an appropriate signal, to reduce the angle a.

In the present Specification "comprises" means "includes or consists of" and "comprising" means "including or consisting of".

The features disclosed in the foregoing description, or the following Claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS: 1. A head-rest arrangement provided on the back-rest of a vehicle

seat, the head-rest arrangement comprising a head-rest unit supported by one or more support arms for pivotal movement about a substantially horizontal pivot axis provided in the region of the top of the back-rest of the seat, there being a deflector mounted within the seat and supported by at least one support arm to effect pivotal movement about the said horizontal axis, the support arm or arms of the head-rest making a predetermined angle a with the support arm or arms of the deflector, a mechanism being provided to reduce the angle a in response to a signal from a sensor.
2. An arrangement according to Claim 1 wherein the head-rest unit incorporates a mechanism to move a front part of the head-rest forwardly in response to a signal from a sensor.
3. An arrangement according to Claim 1 or 2 wherein the deflector incorporates a mechanism to move at least part of the front of the deflector forwards in response to a signal from a sensor.
4. An arrangement according to any one of the preceding Claims wherein a mechanism is provided to lock the relative position of the support arm or arms of the head-rest and the support arm or arms of the deflector when the angle a has been reduced.
5. An arrangement according to Claim 4 wherein the locking mechanism is are associated with a load limiter which enables the angle a to increase, with the absorption of energy, when force levels in excess of a predetermined threshold are experienced.
6. A head-rest arrangement substantially as herein described with reference to and as shown in the accompanying drawings.
7. Any novel feature or combination of features disclosed herein.