WO2005075242A1

WO2005075242A1 - Head restraint

Info

Publication number: WO2005075242A1
Application number: PCT/GB2005/000324
Authority: WO
Inventors: John Davies
Original assignee: Nissan Technical Centre Europe Ltd
Priority date: 2004-02-03
Filing date: 2005-01-27
Publication date: 2005-08-18
Also published as: GB0402271D0; GB2410683B; GB2410683A; GB0501683D0

Abstract

An apparatus for attachment to a head restraint (16) of a seat comprises a cushion element (102), attachment means (114) for releasably attaching the cushion element (102) to the head restraint (16) and a rigid plate (120) disposed within the cushion element (102) for spreading loads applied to the plate. In use, the apparatus is attached to the front of the head restraint to reduce the gap between the head restraint and the user’s head, thereby to reduce injury to the user during a crash.

Description

HEAD RESTRAINT

The present invention is directed to improvements in or relating to head restraints and particularly, but not exclusively, to head restraints for vehicle seats such as those used in automobiles and other road vehicles.

Vehicle seats, such as those used in automobiles and other road vehicles, are generally provided with some form of cushioning to protect the head of the occupant in the event of a crash or the like. Generally known as head restraints, these devices are specifically intended to mitigate injury to the occupant in the event of a rear impact or from the rebound of a frontal impact whereby the occupant experiences a sudden rearward acceleration relative to the vehicle and the seat.

During such events, the occupant's head is accelerated rearwardly and subsequently rotated. The forced rotation of the occupant's head and subsequent extension of the neck imposes excessive forces on the neck which can be injurious.

This effect, usually known as "whiplash", is one of the most common injuries suffered by vehicle occupants involved in front or rear impacts and can be one of the most serious to the occupant owing to the relatively fragile nature of the human vertebrae. Serious and debilitating whiplash injury can be sustained by vehicle occupants even in relatively minor incidents or collisions.

The purpose of the head restraint is to limit the extension and, ideally, the rotation of the head resulting from an impact in order to reduce injury to the occupant. Head restraints can take a variety of forms. In most vehicles, for example, the head restraint is a separate part of the seat, being adjustable in height relative to the seat itself and often fully removable. In other seats, such as those employed in sports cars or the like, the head restraint may be integrally formed with the seat and may be non-adjustable. A disadvantage of most forms of head restraint is that their position relative to the occupant's head varies with the recline angle of the seat back itself. An increase in the reline angle of the seat moves the head restraint further from the occupant's head which increases the time taken for the head to contact the head restraint. In the event of a crash or the like, the head is thus allowed to rotate further before it is supported by the head restraint, thereby increasing the extension of the neck and hence the injuries sustained by the occupant.

In some, relatively expensive vehicles, this problem has been addressed by providing a head restraint which can be adjusted, often by means of electric motors, in a number of directions relative to the seat, including in a direction bringing it closer to the back of the occupant's head following reclining of the seat. Still other forms of head restraint are formed in two parts, one part being fixed to the seat and the other part being hinged to the first part so that it can be pivoted forwardly bringing it closer to the occupant's head. Nevertheless, these proposals do not solve the problem fully and are frequently complex and expensive additions which cannot profitably be fitted to lower cost vehicles.

It is an aim of the present invention to provide an apparatus which addresses this problem. It is a further aim of the invention to provide an apparatus which can be fitted to existing seats with little or no modification thereto and removed quickly and easily without adversely affecting or compromising the functionality or aesthetics of the original head restraint.

According to one aspect of the present invention, therefore, there is provided an apparatus for attachment to a seat having a head restraint or a head restraint portion, the apparatus comprising a cushion element, attachment means for releasably attaching the cushion means to the head restraint or head restraint portion of the seat and means for spreading load applied to the cushion element comprising a rigid plate disposed within the cushion element. The plate may be formed from a plastics or other suitable material and may be located wimin the recess formed within the cushion element, where present. Preferably, the plate lies in direct contact with the head restraint or head restraint portion.

The cushion element may, in use, be located between the head restraint or head restraint portion of the seat and the head of an occupant thereof. In one embodiment, the cushion means is arranged to abut against the head restraint or head restraint portion of the seat.

The attachment means may comprise a recess formed within the cushion element for receiving therein at least a part of the head restraint or head restraint portion. The recess may be sized and shaped to provide close cooperation between the cushion element and the head restraint or head restraint portion. The tight fit between the cushion element and the head restraint or head restraint portion provided by the recess may, in use, retain the cushion element in place adjacent to or against the head restraint or head restraint portion.

The attachment means may alternatively or additionally comprise one or more straps arranged to wrap around the head restraint or head restraint portion thereby to hold the cushion element thereagainst.

The apparatus may further comprise means for limiting, hindering or substantially preventing upward and/or rearward movement of the cushion element relative to the head restraint or head restraint portion. The means for limiting, hindering or substantially preventing upward and/or rearward movement of the cushion element relative to the head restraint or head restraint portion may comprise at least one tab located on or about a lower region of the cushion element for securing to a lower region of the head restraint or head restraint portion or to the seat. In one embodiment, the apparatus is arranged for attachment to a head restraint of the type having one or more stems legs, by which the head restraint is attached to the seat. In this embodiment, the or each tab is provided with an aperture through which, in use, a respective leg extends, thereby to secure the tab to the leg.

The apparatus may fiirther comprise cover means for covering the cushion element. The cover means may comprise a bag within which the cushion element is disposed, the bag having an opening for insertion of the head restraint or head restraint portion therein. The bag may be formed from a fabric material, which may be elasticated or non-elasticated, and may be arranged, in use, to be stretched over the head restraint or head restraint portion thereby to retain the cushion element in position against or adjacent thereto. In one embodiment, the bag or constitutes the attachment means.

In one embodiment, the cushion element comprises a shaped block of open- or closed-cell foam. In one embodiment, the cushion element comprises an inflatable or fillable envelope or sac. The envelope or sac may include a pressure release valve to selectively release the fluid contained therein.

The present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 illustrates a known form of vehicle seat having a head restraint;

Figure 2 illustrates the effect on head restraint position of adjusting the seat back recline angle of the seat of Figure 1;

Figure 3 illustrates the effect of rearward acceleration on the occupant of the seat of Figure 2;

Figure 4 illustrates an apparatus embodying a first form of the invention; Figure 5 illustrates the apparatus of Figure 4 in use;

Figure 6 illustrates an apparatus embodying a second form of the invention;

Figure 7 illustrates the apparatus of Figure 6 in use;

Figure 8 illustrates the position of the apparatus of the invention relative to the occupant of the seat in use;

Figure 9 illustrates the effect of adjusting the seat back recline angle of the seat with the apparatus of the invention in situ;

Figure 10 illustrates a modification to the apparatus of Figures 4 and 5; and

Figure 11 illustrates a modification to the apparatus of Figures 6 and 7;.

Referring firstly to Figure 1, a known form of vehicle seat is shown generally at 10. The seat, which is shown, non-limitingly, as a front seat of an automobile, has a seat cushion or squab (not shown) and a seat back 12. The seat back 12 is pivotally or rotatably connected to the cushion which enables it to be reclined relative thereto. An upper part 14 of the seat back 12 carries a head restraint 16 in the form of a trimmed foam cushion 18 which is supported by a frame having two stem legs 20.

The stem legs 20 of the head restraint frame (not shown) extend through and engage with a mounting bracket 22 which is itself rigidly mounted to a frame 24 of the seat back 12. Clips (not shown) disposed on the upper surface of the seat back 12 engage with the stem legs 20 so as to retain the head restraint 16 at the desired position above the seat back. The clips can be manually disengaged or released so as to allow the head restraint 16 to slide in the direction of the arrow A relative to the seat back 12 thereby to permit the height of the head restraint 16 relative to the seat back 12 to be adjusted. Such adjustment of the head restraint 16 is usually performed to suit the size of the occupant.

As described above, and referring to Figure 2, the seat back 12 of the seat 10 can be reclined relative to the seat cushion. This reclining action is achieved by means of a recliner mechanism (not shown) coupling the seat back 12 to the seat cushion. The occupant, and particularly the vehicle driver, may frequently adjust the seat back recline angle in order to improve comfort or to increase the distance between the shoulders and the steering wheel without altering the distance between the seat and the vehicle foot pedals.

However, as clearly illustrated in Figure 2, owing to the manner in which the head restraint 16 is mounted to the seat back, which allows movement of the head restraint 16 relative to the seat back 12 only in a direction generally parallel to the seat back, increasing the recline angle of the seat back 12 causes the head restraint to pivot away from the occupant. Since the natural tendency of the human occupant is to maintain the head upright whilst driving, this pivoting movement of the head restraint results in an increased distance between the head restraint 16 and the occupant's head 28.

Figure 3 illustrates the effect on the occupant of a sudden rearward acceleration relative to the vehicle, such as might be experienced in a rear impact or due to the rebound of a frontal impact. In the drawing, the horizontal line represents the level of the top of the occupant's head 28 in a normal seating position while the vertical line illustrates the fore/aft and rotational position of the head. In the event of sudden rearward acceleration of the occupant relative to the seat, the occupant's head 28 is forced backward (Figure 3b), inflicting a shear force on the neck followed by a forced rotation of the head (Figure 3c). Here, the vertical line is rotated to illustrate the extent of rotation of the head. The rotation of the occupant's head 28 subsequently causes the neck to extend and ultimately exerts a tensile force on the neck (Figure 3d).

The shaded area B represents the gap between the back of the occupant's head and the front of the head restraint 16 and is known as "back-set". As the back-set increases, the time taken for the head 28 to contact the head restraint also increases.

Thus, the effect of reclining the seat back 12, thereby increasing the distance between the head restraint 16 and the occupant's head 28, is that the head 28 is permitted to move further backward in the event of a rear impact before being supported by the head restraint 16. This in turn allows a greater shear force to be applied to the head and neck, increasing the extension thereof and the rotation of the head. The overall effect is to dramatically reduce the effectiveness of the head restraint to mitigate injury to the occupant and, in fact, injuries sustained in rear impacts when the seat back is reclined so that the head restraint 16 is further than 70mm from the rear of the occupant's head are frequently far more serious than those sustained where the head restraint is in the normal position.

However, many vehicle drivers and passengers inadvertently recline their seats to angles which may compromise the protection afforded by the head restraint 16. Although some seats do provide head restraints which can move fore/aft relative to the seat back so that, after reclining the seat, the occupant can adjust the head restraint to move it closer to the head, these are generally expensive and are therefore usually fitted only to high level vehicles. Also they cannot be retrofitted to older vehicles. Other types of vehicle seats have active anti-whiplash systems built in which automatically bring the head restraint closer to the back of the occupants head in a rear impact greater than a certain magnitude. However, these too are very costly and cannot be retrofitted.

Referring now to Figures 4 and 5, these illustrate a first form of apparatus according to the invention. The apparatus, shown generally at 100, consists of a cushion element 102 formed from a shaped block of foam or other relatively soft, energy absorbing material. The cushion element has a front face 104 which, although shown as generally flat in the drawing, may be contoured to provide comfortable support for the occupant's head. The cushion element 102 also has a rear face 106 which is provided with a cavity or recess 108. The recess 108 is sized and shaped to receive, and engage with, at least a part of the head restraint 16 of an existing vehicle seat, as shown in Figure 5.

Specifically, in the illustrated embodiment and best shown in Figure 5, an upper rear edge 110 of the recess 108 is arranged such that, in use, it partially wraps around the upper surface of the head restraint 16. The lower rear edge 112 of the recess 108 does not, in use, extend beyond the lower surface of the head restraint 16 but instead is provided with securing means in the form of two flexible flaps or tabs 114 which are attached to, or integral with, the cushion element 102. Each tab 114 has a respective aperture 116 disposed therein which may be surrounded by a generally rigid grommet 118. The purpose of the tabs 114 is described below.

A rigid plate 120 is disposed within the recess 108 which, in use, lies substantially plane parallel to the front surface 16a of the head restraint 16 and in close proximity therewith. Although the illustrated embodiment shows a gap between the plate 120 and the front surface of the head restraint 16, this is shown only for clarity and the plate 120 is preferably in direct abutment with the front surface 16a of the head restraint 16 on one side and with the front inner surface 108a of the recess 108 on the other side.

The plate 120 constitutes load spreading means for spreading or dissipating loads which are applied to the cushion element 102 evenly across the entire surface of the original head restraint 16. The energy from the head contacting the head restraint is managed by means of the energy absorbing foam of the cushion element 102 disposed on the front face of the plate. In use, the head restraint 16 is removed from the seat in the manner described above and each leg 20 is inserted into a respective one of the apertures 116 in the tabs 114 attached to the lower rear edge of the cushion element 102. The head restraint 16 is reattached to the seat and the cushion element 102 is placed against the front surface thereof. The cushion element 102 is then pressed over the head restraint 16 such that the latter is inserted, or partially inserted, into the recess 108 in the rear surface 106 of the cushion element 102. The size and shape of the recess 108, together with the curved upper rear edge 110, ensures that there is a relatively tight fit between the cushion element 102 and the head restraint 16 so that the cushion element 102 is retained firmly in place over the head restraint 16. Figure 5 illustrates the position of the cushion element 102 relative to the head restraint 16 in use.

By attaching the cushion element 102 to the stem legs 20 of the head restraint 16, by means of the tabs 114, the cushion element 102 is hindered or substantially prevented from slipping upwards and/or rearwards relative to the head restraint 16 as the occupant forcibly contacts the cushion element, such as in a rear collision or the like. Such movement could otherwise cause the cushion element 102 to detach from the head restraint 16, rendering it less effective.

Some vehicles are provided with head restraints which have a large central aperture extending merethrough for aesthetic reasons and to give the feeling of spaciousness within the vehicle. While the embodiment of Figures 4 and 5 is quite suitable for use with such head restraints, an alternative arrangement may be considered advantageous.

As illustrated in Figures 6 and 7, therefore, in a modification to this embodiment adapted specifically for use with head restraints having an aperture extending therethrough, the rear surface 106 of the cushion element 102 is provided with a protrusion 140, extending rearwardly from the front surface 108a of the recess 108. The protrusion 140 is adapted for engagement in the aperture 17 disposed in the head restraint 16, as shown in Figure 7. The protrusion 140 is sized and shaped to ensure a relatively tight fit within the aperture 17. This engagement between the protrusion 140 and the aperture 17 in the head restraint 16 assists in retaining the cushion element 102 against the head restraint 16. In all other respects, the apparatus of Figures 6 and 7 may be substantially the same as that of Figures 4 and 5.

It will be appreciated that, in use, the apparatus 100 is positioned between the head restraint 16 and the rear of the occupant's head 28. As shown in Figure 8, this has the effect of significantly reducing the distance between the occupant's head 28 and the front surface of the seat's head restraint. By placing the head restraint closer to the occupant's head, the head has less distance to travel before contacting the cushion element 102 and thus results in a lower degree of head rotation and neck extension. In whiplash-inducing incidents, therefore, the protection afforded by the head restraint (comprising the apparatus and the conventional head restraint together) is greater than would be provided by the conventional head restraint alone.

This is particularly important where the occupant has reclined the seat. As illustrated in Figure 9, for example, with the cushion element 102 in place on or against the head restraint 16, the head restraint is positioned no further away from the back of the occupant's head at most normal angles of recline than that of a conventional head restraint in a fully upright seat position.

By reducing the distance between the head restraint and the back of the driver's head, the severity of any whiplash injury sustained in a rear impact or the like is substantially reduced.

While the above described embodiments illustrate workable solutions to the problem of reducing whiplash injuries, it will be appreciated than various modifications and improvements can be made to the invention. For example, as shown in Figures 10 and 11, which illustrate modifications to the embodiments of Figures 4 and 5, respectively, the cushion may be located within an outer cover in the form of a sock or bag 150 having an opening at the bottom thereof. The bag is elasticated and is sufficiently large to accommodate both the cushion element 102, including the spreader plate 120, and the original head restraint 16.

In use, the bag 150 is stretched over the head restraint 16 and the cushion element 102 located on or against the front of the head restraint as described above. The bottom of the bag 150 can be closed by means of suitable closure means such as Velcro® attachments 152, zips, buttons etc. Advantageously, the bag 150 can be made from a material or fabric which matches or complements the existing upholstery of the seat.

It will be understood that the cushion element 102 can take any desired shape> In practice, this will be strongly influenced by the shape of the seat and/or head restraint 16 with which it is to be used. The recess 108 described with regard to the embodiments of Figures 4 to 8 serves primarily to attach the cushion element 102 to the head restraint 16 relatively securely. However, the use of such a recess is optional and any other suitable fixing means can be used for mounting the cushion element 102 on the head restraint 16. For example, the cushion element 102 may be attached to the head restraint 16 by means of straps or clips or simply by the resfraining action of the bag 150.

The use of the tabs 114 through which the stem legs 20 of the head restraint 16 extend in order to hinder or prevent upward and/or rearward movement of the cushion element 102 relative to the head restraint 16 is advantageous but not essential. Other means such as straps or clips can be employed to prevent such upward and/or rearward movement. Alternatively, the rear surface of the cushion element 102 may be covered with a material which provides a relatively high frictional force between the cushion element 102 and the front surface of the head restraint 16 to hinder such relative movement.

The cushion element 102 may be made from any suitable material including closed- or open-cell foam. Alternatively, the cushion element 102 may comprise a sac or bladder which can be filled with polystyrene balls or the like or which is inflatable by means of a pump or by a simple bite valve. Where the cushion element 102 is inflatable, a pressure relief valve may be included to selectively relieve the pressure in the sac in order to manage the energy of the occupant's head 28 forcibly contacting the cushion element, such as in a rear impact. This may assist in preventing the head 28 from bouncing off the cushion element 102 which could increase the forces exerted on the neck. By expelling the air from the sac through a valve at a suitable rate by the force of the head contacting the apparatus, the energy of the impact can be managed and injury to the occupant mitigated.

The front or forward-facing surface 104 of the cushion element 102 may be shaped or contoured to provide comfortable support for the occupant's head 28 while the rear surface 106 may be suitably shaped to ensure that it seats correctly on or against the head restraint 16.

In one embodiment (not shown) the cushion element 102 is substantially C-shaped in cross-section, having upper and lower rear edges which wrap around the upper and lower surfaces of the original head restraint. The original head restraint is inserted in the recess within the cushion element defined by the C-shape which thus grips the head restraint securely but which allows the cushion element to be easily removed therefrom. In this embodiment, therefore, no tabs or the like may be required, the shape of the cushion element itself hindering or substantially preventing rearward and/or upward movement of the cushion element relative to the head restraint. It will be appreciated that the present invention addresses the potential conflict between seat comfort and crash safety by providing an attachment for a conventional vehicle seat and/or head restraint which can be selectively attached or removed by the vehicle user without adversely effecting or compromising either the functionality or the aesthetics of the original head restraint. The apparatus brings the head restraint closer to the occupant's head thereby increasing the protection afforded to the occupant in the event of a rear impact or other event which causes sudden rearward acceleration of the vehicle occupant.

It is known that some vehicle users prefer not to have the head restraint close to or touching the back of the head whilst others often wish to use the head restraint as a literal "head rest" and thus require the head restraint to be positioned very close to the back of the head. Most original-fit head restraints cannot cater for both requirements and usually favour the former user type. The apparatus of the invention, however, can be fitted to original-fit head restraints to provide the comfort and added safety of a head restraint positioned much closer to the head.

No modification to the original head restraint is required and the apparatus imposes no adverse effect on the head restraint itself. It may be particularly useful for users who regularly use different vehicles, such as users of rental cars or "pool" cars, or where a single vehicle is used by different people who prefer different back-set positions.

The invention can be used with conventional or integral head restraints as well as lever-type active head restraints, and on either front or rear vehicle seats. The apparatus is simple and inexpensive to manufacture and can be easily fitted by the vehicle user.

Claims

1. An apparatus for attachment to a seat having a head restraint or a head restraint portion (16), the apparatus comprising a cushion element (102), attachment means (108, 140, 150) for releasably attaching the cushion element (102) to the head restraint or head restraint portion of the seat and means (120) for spreading load applied to the cushion element (102) comprising a rigid plate (120) disposed within the cushion element (102).

2. An apparatus as claimed in claim 1 wherein the cushion element (102) is arranged, in use, to be located between the head restraint or head restraint portion of the seat (16) and the head of an occupant thereof.

3. An apparatus as claimed in claim 1 or claim 2 wherein the cushion element (102) is arranged to abut against the head restraint or head restraint portion of the seat.

4. An apparatus as claimed in any preceding claim wherein the attachment means comprises a recess (108) disposed within the cushion element (102) or in a rear surface thereof whereby the head restraint or head restraint portion of the seat (16) can be partially or fully inserted into the recess (108) thereby to attach the cushion element (102) thereto.

5. An apparatus as claimed in any preceding claim wherein the attachment means comprises, or further comprises, a protrusion (140) disposed on the rear surface of the cushion element (102) or witriin the recess, the protrusion (140) being adapted for engagement in an aperture (17) disposed within the head restraint or head restraint portion of the seat (16).

6. An apparatus as claimed in any preceding claim further comprising means (114, 150) for limiting, hindering or substantially preventing upward and/or rearward movement of the cushion element (102) relative to the head restraint or head restraint portion (16).

7. An apparatus as claimed in claim 6 wherein the means (114) for limiting, hindering or substantially preventing upward and/or rearward movement of the cushion element (102) relative to the head restraint or head restraint portion (16) comprises at least one tab (114) located on or about a lower region of the cushion element (102) for securing to a lower region of the head restraint or head restraint portion (16).

8. An apparatus as claimed in claim 7 for attachment to a head restraint of the type having one or more legs (20) by which the head restraint is attached to the seat, wherein the or each tab (114) is provided with an aperture (116) through which, in use, the or each leg (20) extends, thereby to secure the tab to the leg.

9. An apparatus as claimed in any preceding claim further comprising cover means (150) for covering the cushion element (102).

10. An apparatus as claimed in claim 9 wherein the cover means comprises a bag (150) witiiin which the cushion element (102) is disposed, the bag having an opening for insertion of the head restraint or head restraint portion (16) therein.

11. An apparatus as claimed in claim 10 wherein the bag (150) is resiliently flexible and is arranged, in use, to be stretched over the head restraint or head restraint portion (16) thereby to retain the cushion element (102) in position against or adjacent to the head restraint or head restraint portion.

12. An apparatus as claimed in claim 11 wherein the bag (150) constitutes the attachment means and/or the means for limiting, hindering or substantially preventing upward and/or rearward movement of the cushion element (150) relative to the head restraint or head restraint portion (16).

13. An apparatus as claimed in any preceding claim wherein the cushion element (102) comprises a shaped block of open- or closed-cell foam.

14. An apparatus as claimed in any of claims 1 to 12 wherein the cushion element (102) comprises an inflatable envelope or sac.