WO1998006597A1

WO1998006597A1 - A back support for a vehicle seat

Info

Publication number: WO1998006597A1
Application number: PCT/SE1997/001346
Authority: WO
Inventors: Martin LINDSTRÖM; Lennart Johansson
Original assignee: Autoliv Development Ab
Priority date: 1996-08-14
Filing date: 1997-08-14
Publication date: 1998-02-19
Also published as: GB9617045D0; GB2316304B; DE19781938T1; GB2316304A

Abstract

The back support for a vehicle seat comprises a frame (2, 3, 4) of inverted 'U' section, and a flexible cruciform element (9) located in the space bounded by the frame. The upper arms (10, 11) of the cruciform element (9) are connected to the frame. The lower arms (12, 13) are connected to wires (14, 15) and means are provided to apply tension to the wires in response to a rear impact of the motor vehicle so that the cruciform element becomes rigid. The rigid cruciform element (9) prevents the torso of an occupant of the vehicle passing rearwardly through the frame. The wires (14, 15) in one embodiment are fixed to an anchor point and the frame is adapted to move rearwardly relative to the anchor point in response to the rear impact, thus tensioning the wires. Alternatively, pyrotechnic pre-tensioners are provided associated with the wires.

Description

A BACK SUPPORT FOR A VEHICLE SEAT

THE PRESENT INVENTION relates to a back support for a vehicle seat and more particularly relates to a back support for a vehicle seat intended for use in a motor vehicle such as a motor car.

A typical back support which forms part of a vehicle seat comprises an outer peripheral frame which is of inverted "U" form, the frame supporting one or more transverse resilient elements in the form of springs, straps or bands of elastic material, or a wire frame supported by a plurality of springs, the transverse elements or the frame being covered with padding and upholstery.

The outer peripheral frame should ideally have substantial strength to be able to withstand forces applied to the back of the scat in, for example, a rear impact.

If there is a rear impact, the vehicle may be accelerated forwardly, veiy suddenly, with a high degree of acceleration. In this situation- the body of the occupant of the seat tends to remain stationary, due to its inertia, whilst the seat itself is moved forwardly as a consequence of the forward movement of the vehicle. This can apply a very substantial force to the back of the scat. If the force 2 that is applied is off-set, or not applied evenly to the seat back, the frame of the seat back may need substantial strength to prevent it collapsing.

The lower part of the back of the seat may thus need additional strength to support the torso of the occupant of the seat and this can be provided by rigid elements fixed to the lower section of the peripheral frame.

However, it is desirable for the central part of the back of the seat that is to say, the part of the back of the seat located within the outer periphery defined by the inverted "U" frame to be relatively soft If this part of the back of the seat is made of a hard or rigid material, it is uncomfortable, not only for the occupant of the seat but possibly also for a person occupying a rear seat within the vehicle located behind e seat under consideration The occupant of such a rear seat may have their knees pressed against the back of the seat under consideration and if the central part of the back of the seat contains one or more rigid members, the occupant of the rear seat will be uncomfortable.

However, it is also desirable for the central part of the back of a vehicle seat to be able to withstand a rearwardly directed force, such as the force that will be exerted on the back of the seat by the torso of an occupant of the seat should a rear impact occur. If the outer peripheral frame is very strong and remains in position, and if the central part of the back of the seat does not have sufficient strength, the torso of t e occupant of the seat may move rearwardly, with the torso of the occupant passing partially, or completely, through the central spaces defined by the inverted "U" frame. This is clearly undesirable.

The present invention seeks to provide an improved back support far a vehicle seat. 3 According to this invention there is provided a back support for a motor vehicle seat the back support comprising a relatively strong peripheral frame of inverted "TJ" form, there being at least one flexible element located within the area bounded by the frame, the element initially being substantially untensioned, means being provided to apply tension to said element in response to a rear impact of the motor vehicle to make the element substantially rigid, the element then extending across the area bounded by the frame to prevent the torso of an occupant of the seat passing through the frame.

Preferably said element is associated with one or more flexible means extending from the element the means provided to apply tension to the flexible means in response to a rear impact of the motor vehicle being connected to apply tension to said flexible means.

Conveniently means are provided to mount the seat back movably with respect to a primary support, the said flexible means extending from the frame to an anchor point which is fixed in position relative to the primary support.

Advantageously the said frame is connected to an intermediate support, the intermediate support being movably connected to the primary support.

Preferably the frame is connected to the intermediate support by means of an adjustable recliner connection.

In an alternative embodiment the means to apply tension comprise at least one pyrotechnic tensioner, which is associated with triggering means to which sense a rear impact to activate the tensioner. 4 Advantageously said flexible clement is of cruciform configuration, having two arms connected to the frame and two arms connected to said means to apply tension.

Preferably the said flexible element is fabricated from nylon or polyamide material.

The invention also relates to a vehicle seat incorporating a seat back support as described.

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 an elevational view of the interior part of a back support of a vehicle scat

FIGURE 2 is a side view of the assembled back support of a vehicle seat incorporating the interior part of Figure 1, in a first position,

FIGURE 3 is a view corresponding to Figure 2 showing the back support of the vehicle seat in an alternative position, and

FIGURE 4 is a view corresponding to Figure 1 illustrating a modified embodiment of the invention.

Referring initially to Figure 1 of the accompanying drawings, the interior part of the back support of a vehicle scat which is intended to be covered with, padding and upholstery, comprises an inverted "U" frame 1. The frame 1 5 comprises a transverse top piece 2, and two depending side arms 3,4. The lower regions 5,6 of the side arms are inwardly cranked and are each adapted to be connected to a respective recliner mechanism.

The top upper comers of the inverted TJ" frame 1 are reinforced by diagonally extending reinforcing elements 7,8. A cruciform clement 9 is provided of a substantially "X" configuration which substantially spans across the area bounded by the inverted TJ" frame 1. The cruciform element 9 may be formed of any appropriate flexible material, but may be woven from a nylon or polyamide material such as is used in the manufacture of vehicle safety-belts. If extra strength is required the element 9 can be made from metal.

The two upper arms 10, 11 of the cruciform element 9 are connected to the diagonal reinforcing elements 7, 8. Each of the lower arms 12,13 of the cruciform element has a respective wire 14,15 connected to it Each wire passes through a guide passage 16,17, in the form of a sleeve similar to that found on a Bowdcn cable, the guide passages 16,17 terminating at mounting blocks 18,19 which are secured to the side aims 3,4 of the frame 1. The wires 14,15 project beyond the mounting blocks 18,19 for a purpose that will become clearer hereinafter.

Referring to Figure 2 of the drawings, the side arm 4 of the frame can be seen, together with the mounting block 19 that is mounted on it and the associated guide passage 17.

The lower part of the side arm 4 is connected, by means of a recliner mechanism 20 to an intermediate support plate 21. The intermediate support plate 21 is connected to a primary support plate 22. The primary support plate 22 is 6 connected to the frame associated with the squab of the seat that frame being connected to the floor of the motor vehicle.

It can be seen that the wire 15 emerging from the block 1 extends to an anchor point 23 provided on the primary support plate.

The seat illustrated is provided with padding and upholstery 24 and is also associated with a head-rest 25.

In this initial condition of the seat there is no substantial tension present in the wire 15 (and also no substantial tension present in the wire 14) and consequently, there is substantially no tension in the flexible cruciform element 9, which is thus relatively slack. The cruciform element will thus "give" if a person sitting on the seat presses their back firmly against the back-rest of the seat. Also, if a person sitting behind the seat engages their knees with the rear part of the back of the seat their knees will not encounter any rigid obstruction.

The cruciform clement may form part of a lumbar support for the occupant of the seat

The seat illustrated is designed so that should the vehicle in which the seat is mounted be involved in a rear impact the back of the seat will move relative to the squab of the seat in a generally rearward sense. Whilst the back of the seat could be designed to pivot for example about the axis defined by the recliner mechanism 20, in mis particular embodiment the intermediate support plate 21 is adapted to move rearwardly relative to the primary support plate 22, thus moving the whole of the back of the seat rearwardly. 7 If reference is made to Figure 3 of the accompanying drawings, the situation that exists after a rear impact has occurred is illustrated. It can be seen that the back of the seat has moved rearwardly relative to the primary support plate 22, with the intermediate support plate 21 also moving relative to the primary support plate 22, thus moving the axis of the recliner mechanism 20 rearwardly. However, the anchor point 23, which is connected to the primary support plate 22, has remained stationary. This means that the mounting block 19 has moved rearwardly, relative to the position that it occupied when the seat was in the condition illustrated in Figure 2, whereas the anchor point 23 has remained stationary. This has applied tension to the wire 15. A similar tension has been applied to the wire 14. The cruciform element 9 has consequently been tensioned and forms a very rigid element able to withstand a substantial force. It will also help the frame to withstand an offset load.

As a consequence of the rear impact the base of an occupant 25 of the seat shown in phantom in Figure 3, will tend to move rearwardly relative to the back of the seat tending to move through the inverted TJ" frame 1 within the back of the seat if the impact is severe. The rigid cruciform element 9 extends across the area bounded by the frame I to prevent the torso of the occupant 25 of the seat passing rearwardly through the inverted TJ" frame 1.

Because of the nature of the woven fabric from which the described cruciform element 9 is made, if the force that is applied to the cruciform element exceeds a predetermined threshold, the fabric will begin to stretch, and will stretch by a limited amount thus preventing an over-excessive force being applied to the torso of the occupant of the seat.

It is to be appreciated that whilst in the embodiment of Figure 1, an intermediate support plate moves rearwardly relative to the primary support plate, 7

8 thus allowing the back of the seat to move rearwardly, the back of the seat could be adapted to pivot rearwardly, and the wire 15 (together with the wire 14) would be connected to an appropriately located anchor point so that as a consequence of the rotation of the back of the scat a tension is imparted to the wire.

In an alternative embodiment of the invention, alternative means may be provided for applying tension to the cruciform element when a rear impact occurs. Referring now to Figure 4, which illustrates an alternative embodiment of the invention where the same reference numerals are utilised as in Figure 1 for the same parts (which will thus not be re-described), it can be seen that the wires 14 and 15 are each connected to a pyrotechnical tensioner 26,27. Each pyrotechnic tensioner comprises a pyrotechnic charge adapted to supply gas to a cylinder which contains a piston, the piston being connected to the wire 14 or 15. As a consequence of actuation of the pyrotechnic pre-tensioners 26,27, a substantial tension may be imparted to the wires 14,15. Each of the pyrotechnic tensioners 26,27 will be activated in response to a signal from a sensor adapted to sense a rear impact of the motor vehicle.

Thus, in response to a rear impact the initially untensioned flexible cruciform element 9 will be teπsioned and become rigid, extending across the area bounded by the frame 1, to prevent the torso of the occupant 25 of the seat passing rearwardly through the inverted TJ" frame 1.

Claims

CLAIMS:

1. A back support for a motor vehicle seat the back support comprising a relatively strong peripheral frame of inverted J" form, there being at least one flexible element located within the area bounded by the frame, the element initially being substantially untensioned, means being provided to apply tension to said element in response to a rear impact of the motor vehicle to make the element substantially rigid, the element then extending across the area bounded by the frame to prevent the torso of an occupant of the seat passing through the frame.

2. A seat back support according to Claim I wherein said element is associated with one or more flexible means extending from the element the means provided to apply tension to the flexible means in response to a rear impact of the motor vehicle, being connected to apply tension to said flexible means.

3. A seat back according to Claim 2 wherein means are provided to mount the seat back movably with respect to a primary support, the said flexible means extending from the frame to an anchor point which is fixed in position relative to the primary support.

4. A seat back according to Claim 3 wherein the said frame is connected to an intermediate support, the intermediate support being movably connected to the primary support.

5. A seat back according to Claim 4 wherein the frame is connected to the intermediate support by means of an adjustable recliner connection 7

10

6. A seat back according to Claim 1 or 2 wherein the means to apply tension comprise at least one pyrotechnic tensioner, the tensioner being associated with triggering means which sense a rear impact to activate the tensioner.

7. A seat back according to any one of the preceding Claims wherein said flexible element is of cruciform configuration, having two arms connected to the frame and two arms connected to said means to apply tension.

8. A seat back according to any one of the preceding Claims wherein the said flexible element is fabricated from nylon or polyamidc material.