GB2330068A

GB2330068A - Improvements in or relating to an accessory for a vehicle seat

Info

Publication number: GB2330068A
Application number: GB9721581A
Authority: GB
Inventors: Karl-Erik Tommy Andersson; Jan Ulrik Odenmo; Ola Bostrom; Bertil Mattson
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1997-10-10
Filing date: 1997-10-10
Publication date: 1999-04-14
Anticipated expiration: 2017-10-10
Also published as: GB2330068A8; GB2330068B8; GB2330068B; GB9721581D0

Abstract

An accessory(20) for a vehicle seat is provided to enable the seat to tilt rearwardly in a controlled manner in a real-impact situation. The accessory(20) comprises a housing(21) which is secured(24) to the shell of the vehicle and which receives one end of a strip(22), the other end of which is also secured(27) to the shell of the vehicle. The strip has a line of mechanical weakness(28) defining a tab(29) one end of which(35) is secured to the seat. If the seat commences to tip rearwardly, the line of mechanical weakness(28) tears and the tab(29) extends out of the plane of the strip. Subsequently, part of the strip(22) initially within the housing(21) is pulled out of the housing against a frictional effect and with a bending of the strip.

Description

DESCRIPTION OF INVENTION "IMPROVEMENTS IN OR RELATING TO AN ACCESSORY FOR A VEHICLE SEAT" THE PRESENT INVENTION relates to an accessory for a vehicle seat, and more particularly relates to an accessory for a vehicle seat which provides the vehicle seat with an ellhanced peifoimance in the event that a rear impact should occur.

The accessory may be built into the seat, or may be provided to be retrofitted to a seat.

It has been appreciated that if a motor vehicle, such as a motor car, is involved in a rear-end collision, or rear impact, - that is to say if a following vehicle runs into the back of the car - the occupants of the struck car often suffer from neck injulies.

It is to be understood that during a rear-end collision of this type, the vehicle that is struck is subjected to a forward acceleration. This imparts a forward acceleration to the seats of the vehicle. The squab and the back of each occupied seat engage the posterior and torso of the occupant of the seat and impart a substantial acceleration to the posterior and torso of the occupant. However, no corresponding acceleration is immediately imparted to the head of the occupant.

The head is a part of the body that has substantial mass, and consequently the head has substantial inertia.

Thus, whilst the posterior and torso of the occupant of the vehicle are accelerated forwardly as a result of the rear-end collision, the head of the occupant of the vehicle initially remains stationary. This causes the neck initially to adopt a "S"-shaped configuration as the lower part of the neck moves forwardly, whilst remaining vertical, and the upper part of the neck remains in its initial position.

Subsequently, the head begins to rotate, and the neck then occupies a curved configuration. The head subsequently moves forwardly. Research has shown that "whiplash" injuries may occur as the neck adopts the "S"-shaped configuration, if the head is moving, relative to the torso, at a substantial speed..

The present invention seeks to provide a fitting for a vehicle seat which, when used with a vehicle seat, will reduce the lisk of whip-lash injuries occurring to the occupant of the seat duiing a rear end collision.

According to this invention there is provided an accessory for a vehicle seat adapted to be connected between part of the vehicle seat and the shell of a vehicle, the accessory being adapted to permit movement of the part of the seat to which it is connected relative to the shell of a vehicle whilst absorbing energy, the accessory comprising an elongate snip, one end of which is adapted to be secured to the shell of the vehicle, and the other end of which is adapted to be retained and guided by means secured to the shell of the vehicle, an intermediate part of the strip being provided with a line of mechanical weakness defining a deformable tab, the tab being provided with means to secure the tab to the seat, the accessory being adapted, during an initial movement of the seat, to absorb a predetermined amount of energy as at least part of the line of mechanical weakness is torn and the tab is deformed from the strip, and also being adapted, during a subsequent movement of the seat, to absorb a second predetermined amount of energy as part of the strip moves relative to the retaining and guiding means.

Preferably the second predetermined amount of energy is greater than the first predetelmined amount of energy.

Conveniently the tab is defined by two substantially parallel lines of mechanical weakness and a substantially arcuate slot which inter-connects the adjacent ends of the lines of mechanical weakness.

Advantageously the fee ends of the parallel lines of mechanical weakness each terminate at a small diameter aperture extending through the strip.

Preferably the means to retain and guide the said end of the strip comprise an elongate axially extending aperture formed in the strip, and securing means extending through the aperture adapted to engage the shell of the motor vehicle.

Conveniently the means to guide an retain the said end of the strip comprise a housing, the housing defining a through-extending passage, the strip being received within the passage.

Advantageously the part of the strip within the housing is deformed to have regions of the strip engaging the housing.

In one embodiment the deformed parts of the strip comprise one or more projections, aligned with the axis of the strip, comprising upstanding projections which engage the interior of the housing to provide a frictional effect.

In an alternative embodiment the deformed portion of the strip comprises a portion of the strip of substantially sinusoidal form, the interior of the housing having co-operating portion of substantially sinusoidal form, the said portion of the strip engaging said portion of the housing.

Preferably the accessory is such that an accessory for a vehicle seat adapted to be connected between part of the vehicle seat and the shell of a vehicle, the accessory being adapted to permit movement of the part of the seat to which it is connected relative to the shell of a vehicle whilst absorbing energy, the accessory comprising an elongate strip, one end of which is adapted to be secured to the shell of the vehicle, and the other end of which is adapted to be retained and guided by means secured to the shell of the vehicle, an intelmediate part of the strip being provided with a line of mechanical weakness defining a deformable tab, the tab being provided with means to secure the tab to the seat, the accessory being adapted, during an initial movement of the seat, to absorb a predetermined amount of energy as at least part of the line of mechanical weakness is torn and the tab is deformed from the strip, and also being adapted, during a subsequent movement of the seat, to absorb a second predetermined amount of energy as part of the strip moves relative to the retaining and guiding means.

The invention also relates to a vehicle seat provided with an accessory as defined above.

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 diag;rammatic view comprising four illustrations showing the condition of the head and neck of an occupant of the vehicle in a rear collision situation where a conventional seat is used.

FIGURE 2 is a diagiammatic view of a vehicle seat, FIGURE 3 is a view of the seat of Figure 1 following a rear impact, FIGURE 4 is a perspective view of an accessory for use with the vehicle seat, FIGURE 5 is a perspective view of one component of the accessory shown in Figure 4, FIGURE 6 is a perspective view of the accessory during a rear impact, FIGURE 7 is a perspective view of the accessory after a rear impact, and FIGURE 8 is a sectional view taken on the line VIII-VIII of Figure 4 illustrating a modified embodiment of the invention.

Refening initially to Figure 1 of the accompanying drawings, illustration A shows the position of the head 1 and neck 2 of the occupant of a motor vehicle during ordinary conditions. The head and neck would occupy this position if, for example, the vehicle were stationary.

Assuming that the vehicle was then subjected to a rear impact, the posterior and torso of the occupant of the vehicle would be moved forwardly, as a consequence of the forward movement of the vehicle and the forward movement of the seat mounted in the vehicle. The head 1 of the occupant would tend to remain stationary. A neck 2 of the occupant would then have the condition shown in illustration B. The neck here has a "S" configuration. Subsequently, as shown in illustration C, the head 1 moves rearwardly, thus giving the neck 2 an arcuate configuration and, if the head does not impinge on the head-rest, the head can move to the tilted back position shown in illustration D where the neck 2 is bent back (hyperextension) with a very sigtiificant device of curvature. The head may then spring forwardly. This sequence of movements provides the "whiplash" effect.

It is believed that if the neck is subject to the distortions shown in illustrations A to D, the hydro-dynamic pressure of the fluid within the spine can rise suddenly, when the neck adopts the "S"-shaped configuration, thus imparting pressure shocks to parts of the central nervous system in contact with that fluid.

Also, injuries may well be imparted to the ganglia. It is believed that this is why patients with so-called "whiplash" injuries may suffer from the effects of those injuries for a long time. Even though a typical rear impact collision occurs with a relatively low impact speed, these collisions are responsible for a large number of relatively serious injuries each year.

It is believed that if a vehicle seat can be adapted, in the event that a rear impact should arise, such that tIle back of the seat moves rearwardly initially against a relatively low energy absorbing force, and subsequently against a relatively high energy absorbing force, the lisk of whip-lash injuries being experienced by an occupant of the seat will be substantially reduced.

As the seat back moves reanvardly against the first energy absorbing force, the torso of the occupant is accelerated only gradually in the forward direction of the motor vehicle. The head of the occupant of the seat remains substantially stationary. The back of the seat will move forwardly until the head of the occupant engages the head-rest of the seat. Subsequently, both the torso and head of the occupant will be given a unifolm acceleration, in the forward direction of the vehicle, whilst the back of the seat moves rearwardly against the second relatively high energy-absorbing force. When the rearward movement of the back of the seat has terminated, it is envisaged that both the torso of the occupant and the head of the occupant will be travelling forwardly at a speed substantially identical to the forward speed of the vehicle.

The present invention seeks to provide an accessory for a motor vehicle seat in the form of an energy absorber which possesses the desired energy absorbing charactelistics.

Refening now to Figure 2 of the accompanying drawings, a vehicle seat 10 is illustrated having a squab 11 and a back 12, having a head-rest 13. The vehicle seat has rear legs 14 and front legs 15. Connected between the front legs 15 and part of the shell of the vehicle, for example the floor 16 of the motor vehicle, is an accessory 17 in the form of an energy absorber. The energy absorber is mounted in position so that, in the event that a real impact occurs, the seat may pivot rearwardly about, for example, the point 18 where the rear legs 14 engage the floor of the vehicle, with the front legs 15 thus moving away from the floor of the vehicle. This movement of the front legs is resisted by the energy absorbing accessory 17.

Referring now to Figures 4 to 6, an energy absorbing accessory 20 is illustrated. The accessory 20 comprises a housing 21 and a deformable strip 22.

The housing 21 forms a retaining and guiding element for the strip 22, and is in the form of a tubular housing defining a flat rectangular cross-sectioned passage 23 extending therethrough. A retaining bolt 24 is provided which extends transversely of the through-passage 23, the bolt 24 being aligned with the axis of the passage.

The strip 22 is a flat strip having a cross-section dimensioned to fit within the through-passage 23. One end of the strip extends through the passage 23 and is provided with an oval elongate slot 25 through which the bolt 24 passes.

The other end of the strip 22 is provided with an aperture 26 which receives a retaining bolt 27 to secure that end of the strip to the floor of the motor vehicle.

Intermediate the housing 21 and the retaining bolt 27 the strip 20 is provided with a substantially U-shaped line of mechanical weakness 28 which serves to define a tab 29. The line of mechanical weakness comprises two axially extending parallel sections 30,31 which commence at respective small apertures 32,33 formed on opposite sides of the axis of the strip. The parallel sections of the line of mechanical weakness are inter-connected, at a position remote from the apertures 32,33 and adjacent the bolt 27 by means of an arcuate slot 34 which is formed in the snip. At the centre of curvature of the arcuate slot 34, an aperture 35 is provided.

As can be seen most clearly in Figure 5, on either side of the oval elongate slot 25, the strip is provided with axially orientated upstanding projections 36,37. The size of the projections 36,37 is such that they form a friction fit within the through-passage 23 formed in the housing 21.

It is to be appreciated that, in use of the accessory as described above, the accessory will be secured to the floor of the motor vehicle by means of the bolts 24 and 27. A bolt will be passed through the aperture 35 to connect the tab 29 to the lower part of the front leg of a vehicle seat.

In the event that a real impact should occur, the vehicle and the seat will move forwardly tending to impart a forward acceleration to the torso of an occupant of the seat. However, the torso of the occupant of the seat will apply a rearwardly directed force to the back of the seat tending to cause the seat to rotate, in a clockwise direction as shown in Figure 3, about the point 18 where the rear legs 14 of the seat 10 contact the floor. During an initial movement of the seat, the parallel sections 30,31 of the line of mechanical weakness, and the tab 29 will be deformed, so that the tab 29 is moved to a position in which it extends upwardly above the rest of the strip. The tearing of the seating 30,31 line of mechanical weakness 28 is facilitated by the presence of the slot 34 and will terminate when the small apertures 32,33 are reached.

It is to be understood that this tearing of the material forming the strip, and the deformation of the snip absorbs a predetermined amount of energy. The commencement of the tearing is facilitated by the presence of the arcuate slot 34 provided at the end of the poition of the strip that is to form the tab 29.

The accessory will thus have the condition illustrated in Figure 6.

If, at the end of this paiticular stage in the operation of the device, the torso of the occupant of the seat is still applying a rearward force to the back of the seat, the tab 29 moves upwardly away from the housing 21. The portion of the strip 22 which is retained within the housing, thus emerges from the housing, with the elongate slot 25 moving forwardly relative to the bolt, as a second movement.

This forward movement is effected against the frictional effect provided by the protrusions 36 and 37 which engage the interior of the through-passage 23. Also energy is absorbed by the resultant bending of the strip 22. The housing 21 serves to guide the strip during this movement, but the presence of the bolt 24 ensures that the strip is retained when a desired degree of movement has been effected, since the bolt will engage the end of the oval elongate slot 25 which is closest to the free end of the strip 22, thus preventing the strips from being withdrawn any further from the housing 21.

During this movement of the strip, energy is absorbed frictionally by the engagement of the projections 36 and 37 with the interior of the housing 21, and also by the deformation of the strips.

The accessory, at the end of a severe rear impact, presents the appearance shown in Figure 7.

It is to be understood that in certain embodiments of the invention, the second movement in which the strip is withdrawn from the guiding and retaining means, may commence before the first movement, in which the line of weakness is torn, has been fully completed.

Figure 8 is a cross-sectional view of a modified embodiment of the invention, showing the strip 22 within the passage 23 in the housing 21. It can be seen that one wall 40 of the housing is provided with a sinusoidal profile, and the strip is provided with a conesponding sinusoidal profile. The two sinusoidal profiles are inter-engaged. It is to be understood that in use of such an embodiment, during the second stage of operation, the sinusoidal portion of the strip must be withdrawn from the housing, with the strip being deformed to such an extent that the peaks and troughs of the sinusoidal part of the strip become disengaged from the peaks and troughs of the sinusoidal part of the housing. Of course, this deformation of the strip absorbs a substantial amount of energy, which will be desirable.

Whilst the invention has been described with reference to one embodiment, with one modification, it is to be appreciated that many modifications may be effected without departing from the scope of the invention. Although the strip, in the described embodiment, is retained and guided by a housing that surrounds the strip, the strip could be retained and guided simply by a bolt passing through an elongate aperture in the snip, or by a housing or channel that engages a relatively narrow "waisted" part of the strip.

Whilst, in the embodiment of the modification described above, two different arrangements are described which provide the effect that energy is absorbed as the strip is withdrawn from the housing, it is to be appreciated that other arrangements could be adopted to provide an equivalent effect. The part of the strip that emerges from the housing might, for example, be provided with deformable projecting tabs which have to be deformed as the free end of the strip is drawn into the housing as a consequence of the main part of the strip being pulled away from the housing. In a fulther embodiment, the strip could be provided with notches or recesses which engage frangible tangs provided within the housing, movement of the strip as a consequence of rearward pivoting of the seat causing the frangible tangs to break, thus absorbing energy.

Claims

CLAIMS: 1. An accessory for a vehicle seat adapted to be connected between part of the vehicle seat and the shell of a vehicle, the accessory being adapted to permit movement of the part of the seat to which it is connected relative to the shell of a vehicle whilst absorbing energy, the accessory comprising an elongate strip, one end of which is adapted to be secured to the shell of the vehicle, and the other end of which is adapted to be retained and guided by means secured to the shell of the vehicle, an intermediate part of the strip being provided with a line of mechanical weakness defining a deformable tab, the tab being provided with means to secure the tab to the seat, the accessory being adapted, during an initial movement of the seat, to absorb a predetermined amount of energy as at least part of the line of mechanical weakness is torn and the tab is deformed from the strip, and also being adapted, during a subsequent movement of the seat, to absorb a second predetermined amount of energy as part of the strip moves relative to the retaining and guiding means.
2. An accessory according to Claim I wherein the second predetermined amount of energy is greater than the first predetermined amount of energy.
3. An accessory according to Claim 1 or 2 wherein the tab is defined by two substantially parallel lines of mechanical weakness and a substantially arcuate slot which inteconnects the adjacent ends of the lines of mechanical weakness.
4. An accessory according to any one of Claims I to 3 wherein the free ends of the parallel lines of mechanical weakness each terminate at a small diameter aperture extending through the strip.
5. An accessory according to any one of the preceding Claims wherein the means to retain and guide the said end of the strip comprise an elongate axially extending aperture formed in the strip, and securing means extending through the aperture adapted to engage the shell of the motor vehicle.
6. An accessory according to Claim 5 wherein the means to guide and retain the said end of the strip comprise a housing, the housing defining a throughextending passage, the strip being received within the passage.
7. An accessory according to Claim 6 wherein the part of the strip within the housing is deformed to have regions of the strip engaging the housing.
8. An accessory according to Claim 7 wherein the deformed parts of the strip comprise one or more projections, aligned with the axis of the strip, comprising upstanding projections which engage the interior of the housing to provide a frictional effect.
9. An accessory according to Claim 7 wherein the deformed portion of the strip comprises a portion of the strip of substantially sinusoidal form, the interior of the housing having a co-operating portion of substantially sinusoidal form, the said portion of the strip engaging said portion of the housing.
10. An arrangement according to any one ofthe preceding Claims in which, in use, the subsequent movement commences before the first movement is fully complete.
11. An accessory substantially as herein described with reference to and as shown in the accompanying drawings.
12. An accessory substantially as herein described with reference to and as shown in Figures 2 to 7 as modified by Figure 8 of the accompanying drawings.
13. Any novel feature or combination of features disclosed herein.