GB2347078A

GB2347078A - Head-rest

Info

Publication number: GB2347078A
Application number: GB9904558A
Authority: GB
Inventors: Martin Lindstrom
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1999-02-26
Filing date: 1999-02-26
Publication date: 2000-08-30
Anticipated expiration: 2019-02-26
Also published as: GB9904558D0; GB2347078B; WO2000050258A1

Abstract

A head-rest arrangement (4) for a seat in a motor vehicle has a main part (6) and a front part (7). Releasable connection means are provided to connect the front part to the main part and to release the front part in response to a rear impact. A resilient spring (21) is provided to bias the front part (7) forwardly while simultaneously drawing air through non-return valves (24) into a chamber formed by a concertina tube (22) of which the spring forms a part. The front part (7) of the head-rest engages the rear of the head of an occupant of the seat, preventing the head of the occupant of the seat moving rearwardly relative to the torso of the occupant of the seat, thus minimising whiplash injuries.

Description

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

The present invention seeks to provide a head-rest for a vehicle seat, and more particularly seeks to provide a head-rest adapted to respond to a rear impact of the vehicle in which the vehicle seat is mounted, in order to minimise the risk of whiplash injury to the occupant of the seat.

It is now known that when a vehicle is subjected to a rear impact, the occupant of a seat within the vehicle, such as, for example, the driver of the vehicle, may suffer from so-called"whiplash"injuries which may be relatively severe, even if the rear impact is only a low velocity impact.

The reason for this is that, when a rear impact occurs to a stationary vehicle, for example, if a following vehicle fails to brake and runs into the back of the stationary vehicle, the stationary vehicle is given a very sudden acceleration. Consequently the floor pan and the seats of the vehicle tend to move forwardly very quickly. The posterior and torso of an occupant of a seat in the vehicle also tend to start moving forward very swiftly, since they are moved forwardly by their engagement with a seat in the vehicle. However, typically the head of an occupant of the vehicle is not in contact with anything and thus, during the initial stages of the rear impact, the torso and lower part of the neck of the occupant of the vehicle tend to move forwardly, whilst the head tends to remain in its initial position.

Of course, the forward movement of the lower part of the neck causes the neck itself to enter a curved state, and then, when the neck is in the curved state, the continuing forward movement of the torso of the occupant of the seat tends to begin to impart a forward motion to the head of the occupant.

However, this forward motion is associated with a twisting motion of the head.

The head is then given a forward motion purely as a consequence of the forward movement of the torso of the occupant of the vehicle.

It is this chain of events that leads to the"whiplash"injury.

The present invention seeks to provide the head-rest which will reduce the risk of"whiplash"injuries occurring.

According to this invention there is provided a head-rest arrangement for a seat in a motor vehicle, the head-rest comprising a main part and a front part, the front part being releasably connected to the main part by releasable connection means, means being provided adapted to bias the front part forwardly of the main part, and means being provided to resist subsequent rearward movement of the front part, relative to the main part, once the front part has been moved forwardly relative to the main part.

Preferably the means adapted to release the front part from the main part are responsive to a rear impact.

Conveniently the means adapted to bias the front part of the head-rest forwardly comprise a resilient element.

Advantageously the resilient element comprises a helical spring.

Preferably the means to resist rearward movement of the head-rest comprise means defining a substantially air-tight chamber, and means physically to expand the chamber as a consequence of forward movement of the front part of the head-rest, non-return valve means being provided to permit the ingress of air to the chamber during expansion of the chamber, the arrangement being such that any force applied to the forward part of the headrest tending to move the head-rest rearwardly, following forward movement thereof, closes the non-return valve means so that the chamber resists such rearward movement.

In a preferred embodiment the helical spring is incorporated within a tube which constitutes said chamber.

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 which : FIGURE 1 is a schematic view of a vehicle seat incorporating a headrest in accordance with the invention, and an occupant of the seat who is shown to be the driver of a vehicle, FIGURE 2 is an enlarged view of part of the head-rest of Figure 1, FIGURE 3 is a view illustrating the arrangement of Figure 1 following a rear impact to the vehicle, FIGURE 4 is an enlarged view of part of Figure 3, FIGURE 5 is a sectional view taken on the line V-V of Figure 4.

Referring initially to the accompanying drawings, a vehicle seat 1 is illustrated, having a squab 2 and a back 3. The back 3 carries a head-rest 4.

Figure 1 illustrates an occupant 5 of the seat, who, in this embodiment, is the driver of a vehicle. The driver has his posterior mounted on the squab 2, and his torso resting against the back-rest 3, with his head being located just in front of the head-rest 4.

Referring to Figure 2 of the accompanying drawings, the head-rest 4 comprises a main body part 6 which defines the rearward portion of the headrest, and a separate front part 7. The front part 7 is releasably connected to the rear part 6 by means of a plurality of releasable connections 8 (only one of which is illustrated). The releasable connection 8 comprises a first apertured lug 10 formed on the main part 6, and a second co-aligned apertured lug 11 formed on the front part 7, there being a"U"-shaped connecting pin 12 having the arms thereof extending tlu-ough the apertures formed in the lugs. The pin 12 is connected to the core 13 of a Bowden cable 14. The Bowden cable 14 extends to a sensor arrangement 15 adapted to sense a parameter indicative of a rear impact of a vehicle in which the seat carrying the headrest 4 is mounted.

It is therefore to be appreciated that in response to a rear impact, the core 13 of the Bowden cable is retracted, thus withdrawing the pin 12 from the apertured lugs 10 and 11 so that no means remain connecting the main body part 6 of the head-rest with the front part 7.

Of course, alternat releasable connecting means may be provided in alternate embodiments of the invention.

Turning now to Figure 3 of the drawings, it is to be understood that in the event that a rear impact is sensed, the front part 7 of the head-rest, which presents a forwardly directed surface 20, which is preferably a padded surface, moves forwardly from the main part of the back-rest 6, so as to engage and retain the rear part of the head of the occupant of the seat.

As can be seen from Figure 4, a resilient spring 21 is provided which, in this embodiment, is a helical compression spring, which is located between the main body part 6 of the head-rest 4 and the separate front part 7. Thus, when the releasable connecting means, i. e. the pins 12, are released or disconnected, the spring 21 biases the fi-ont part 7 of the head-rest forwardly. The spring is selected to be strong enough to move the front part 7 of the head-rest forwardly with a satisfactory velocity. However, the strength of the spring and the weight of the front part 7 of the head-rest are selected so that the front part 7 of the head-rest does not impact violently with the head of the occupant of the seat.

The spring 21 is incorporated into a resilient"concertina"tube 22 of a substantially gas-impervious material which, as the spring 21 becomes extended, as shown in Figure 4, adopts the configuration of a tube. One end of the tube is sealingly connected to the forward part 7 of the head-rest 4 in a substantially air-tight manner. The other end of the tube is sealingly connected in a substantially air-tight manner to a plate 23 within the head-rest.

The plate 23 (as shown in Figure 5) is provided with four equispaced one-way valves 24. Each valve 24 incorporates a flap 25 as shown in Figure 4, and each valve 24 is aligned with a respective chamber 26 formed within the head-rest which communicates with the exterior of the head-rest.

It is to be appreciated, therefore, that as the front part 7 of the head-rest moves forwardly under the biasing effect of the spring 21, air is drawn into a substantially air-tight chamber formed by the concertina tube 22 through oneway or non-retwm valves 24.

The front part 7 of the head-rest will move forwardly, typically by a distance of up to 150mm, to engage the rear part of the head of an occupant of the seat on which the head-rest 4 is mounted, as shown in Figure 3. The front part 7 of the head-rest will move in a substantially unrestrained way under the bias of the resilient means 21. However, the effect of the chamber defined by the concertina tube 21 and the non-retum valves 24 is such that any rearward movement applied to the forward part of the head-rest 7, for example as a consequence of any tendency of the head to move rearwardly relative to the head-rest, is resisted. Whilst a minimal rearward movement of the front part 7 of the head-rest might be permitted, that movement would serve immediately to close the non-return valves 24 and slightly pressurise the air within the concertina tube 22, thus preventing further rearward motion of the front part of the head-rest 4.

Thus, in an accident situation, when a rear impact is detected, the forward part 7 of the head-rest would be released during an initial stage of the rear impact, before any substantial acceleration had been imparted to the posterior and torso of the occupant of the seat. Consequently the forward part of the head-rest would move forwardly from its initial retracted position, as shown in Figure 1, to the extended position as shown in Figures 3 and 4, with the forward part 7 of the head-rest then engaging the rear part of the head of the occupant of the seat. Thus, since the forward part of the head-rest then resists any rearward motion of the head of the occupant of the seat relative to the head-rest, the head of the occupant of the seat will also be accelerated forwardly with an acceleration rate virtually identical with the acceleration rate of the torso of the occupant.

Whilst in the described embodiment the helical spring is incorporated into the concertina tube that constitutes the substantially air-tight chamber, in an alternative embodiment one or more springs maybe provided which are not incorporated in the chamber. Consequently the risk of the torso of the occupant of the seat moving forwardly whilst the head of the occupant of the seat remains stationary is substantially reduced. This means that the risk of "whiplash"injury is also substantially reduced.

Claims

CLAIMS: 1. A head-rest arrangement for a seat in a motor vehicle, the head-rest comprising a main part and a front part, the front part being releasably connected to the main part by releasable connection means, means being provided adapted to bias the front part forwardly of the main part, and means being provided to resist subsequent rearward movement of the front part, relative to the main part, once the front part has been moved forwardly relative to the main part.
2. A head-rest according to Claim 1 wherein the means adapted to release the front part from the main part are responsive to a rear impact.
3. A head-rest according to Claim 1 or 2 wherein the means adapted to bias the front part of the head-rest forwardly comprise a resilient element.
4. A head-rest according to Claim 3 wherein the resilient element comprises a helical spring.
5. A head-rest according to any one of the preceding Claims wherein the means to resist rearward movement of the head-rest comprise means defining a substantially air-tight chamber, and means physically to expand the chamber as a consequence of forward movement of the front part of the head-rest, nonreturn valve means being provided to permit the ingress of air to the chamber during expansion of the chamber, the arrangement being such that any force applied to the forward part of the head-rest tending to move the head-rest rearwardly, following forward movement thereof, closes the non-return valve means so that the chamber resists such rearward movement.
6. A head-rest arrangement substantially as herein described, with reference to and as shown in the accompanying drawings.

6. A head-rest arrangement according to Claim 4 and Claim 5, wherein the helical spring is incorporated within a tube which constitutes said chamber.

7. A head-rest arrangement substantially as herein described, with reference to and as shown in the accompanying drawings.

8. Any novel feature or combination of features disclosed herein.

Amendments to the claims have been filed as follows 1. A head-rest arrangement for a seat in a motor vehicle, the head-rest comprising a main part and a front part, the front part being releasably connected to the main part by releasable connection means, means being provided adapted to bias the front part forwardly of the main part, and means being provided to resist subsequent rearward movement of the front part, relative to the main part, once the front part has been moved forwardly relative to the main part, wherein the means to resist rearward movement of the headrest comprise means defining a substantially air-tight chamber adapted to be physically expanded as a consequence of forward movement of the front part of the head-rest, non-retum valve means being provided to permit the ingress of air to the chamber during expansion of the chamber, the arrangement being such that any force applied to the forward part of the head-rest tending to move the head-rest rearwardly, following forward movement thereof, closes the nonreturn valve means so that the rearward movement is resisted.

2. A head-rest according to Claim 1 wherein the means adapted to release the front part from the main part are responsive to a rear impact.

3. A head-rest according to Claim 1 or 2 wherein the means adapted to bias the front part of the head-rest forwardly comprise a resilient element.

4. A head-rest according to Claim 3 wherein the resilient element comprises a helical spring.

5. A head-rest arrangement according to Claim 4, wherein the helical spring is incorporated within a tube which constitutes said chamber.