IMPROVEMENTS IN OR RELATING TO A VEHICLE SEAT

Abstract: A vehicle seat (1) has a sub-frame (7) supported by a carriage (5) slidably mounted on rails (2). The sub-frame (7) of the seat is pivotally supported by a pivot (12) located towards the rear of the seat. A linkage (14, 17) provided at the front of the seat is connected to one end of a kinetic energy absorbing device (21), the other end of which is fixed in position. In the event of a rear impact the seat pivots about the pivot axis (12), the pivoting movement being resisted by the kinetic energy absorbing element (21).

Description: "IMPROVEMENTS IN OR RELATING TO A VEHICLE SEAT" THE PRESENT INVENTION relates to a vehicle seat, and more particularly relates to a vehicle seat intended for use in a motor vehicle, such as a motor car. It has been proposed previously to provide a vehicle seat which, in the event of a rear impact, moves towards the rear of the vehicle, preferably with a pivoting or tilting action. GB-A- 1,228,657 discloses a seat of this type in which the main body of the seat is pivotally connected to the floor of the vehicle, and the front part of the seat is connected to the floor of the vehicle by a device arranged to absorb kinetic energy. The arrangement is such that, in the event of a rear impact, the seat pivots in a rearward direction about the pivotal connection between the seat and the floor of the vehicle, whilst the device that absorbs kinetic energy becomes extended. It is believed that the risk of a passenger being injured in an accident involving a rear impact may be reduced if a seat of this general type is utilised, and the present invention seeks to provide an improved vehicle seat. The device shown in GB-A- 1 ,228,657 that absorbs kinetic energy extends from the front part of the seat towards the floor of the vehicle just in front of the seat, and consequently may well obstruct the legs of a person sitting in the seat. Additionally, the illustrated device has to have a substantial length in order to permit a desired degree of tilting. According to this invention there is provided a vehicle seat, the seat comprising a support structure located beneath the seat, and a squab located above the support structure, the seat further including a back-rest extending substantially upwardly from the rear part of the squab of the seat, there being means pivotally connecting the rear part of the squab of the seat to the support structure, to permit the rearward tilting of the back-rest of the seat with a simultaneous upward tilting of the squab of the seat, there being a kinetic energy absorbing means adapted to absorb kinetic energy when the seat executes the tilting movement, the kinetic energy absorbing means being located beneath the squab of the seat and having one end thereof connected to one element of a pivotal linkage, the pivotal linkage extending between the support structure and a forward part of the squab of the seat. Preferably the support structure comprises a carriage slidably mounted along rails proved on the floor of the vehicle. Conveniently the pivotal linkage comprises two elements, one element being pivotally connected to the support structure, and also pivotally connected to the other element, the other element being pivotally connected to the squab of the seat. Advantageously the said one element defines three pivot points which are located at the comers of the triangle, one pivot point being connected to the support structure, a further pivot point being connected to the other pivot element, and the third pivot point being comiected to the kinetic energy absorbing means. Preferably the kinetic energy absorbing means had one end thereof connected to the support structure. In one embodiment the kinetic energy absorbing means comprises a piston and cylinder device. Alternatively the kinetic energy absorbing means comprises a metallic plate of arcuate form. Conveniently the metallic plate of arcuate form is provided with a notch or recess formed in the inner edge of the arc to provide a region of mechanical weakness. In a preferred embodiment the point of pivotal connection between the support structure and the rear of the squab of the seat, and the point of pivotal connection of the linkage and the front part of the squab of the seat are adjustably positionable relative to the squab of the seat to permit an adjustment of the position or orientation of the squab of the seat. 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 side view of a seat in accordance with the invention, illustrating the occupant of the seat, the seat being shown in an initial position, FIGURE 2 is an enlarged view of part of the seat of Figure 1 in a first position, FIGURE 3 is a view corresponding to Figure 2 illustrating the seat after a rear impact has occurred, and FIGURE 4 is a view, corresponding to Figure 2, illustrating an alternative embodiment of the invention. Referring initially to Figure 1 of the accompanying drawings, a vehicle seat 1 is provided which is mounted on a rail 2, the rail 2 having lugs 3,4 by means of which the rail may be mounted to the floor of the motor vehicle. A carriage 5 is provided which is mounted on the rail 2 so as to be slidable along the rail 2. The carriage 5 acts as a support structure for the seat 1. The seat 1 has a squab 6 which incorporates a sub-frame 7 which is supported by the carnage 5, as will be described in greater detail below. The seat 1 also has a back 8 having a head-rest 9. The back extends upwardly from a rear part of the squab 6. The seat is shown, in Figure 1 , with an occupant 10. Referring now to Figure 2, it can be seen that the carriage 5 is provided, at its rearward end, with an upstanding lug 1 1 which is of generally triangular fonn. The upper part of the lug caixies a pivot pin 12, which pivotally engages the sub-frame 7. In the illustrated embodiment the pivot pin 12 is accommodated within a vertical oval-shaped elongate slot or aperture 13 fonned in the sub-frame 7, and a mechanism (not shown) is provided to selectively adjust the position of the pivot pin 12 within the slot 13, thus raising and lowering the rear part of the sub-frame 7 relative to the carriage 5, and thus adjusting the position of the squab 6 of the seat. Towards the front of the caπϊage 5, a triangular connecting plate 14 is provided. The lower right-hand comer of the connecting plate 14 is pivotally connected by means of a pivot 15 to the caniage 5. The left-hand lower comer of the plate 14 is connected by a pivot 16 to one end of an elongate lever aim 17, the other end of the lever ami 17 having a pivot pin 18 which is pivotally connected to the sub-frame 7. The pivot pin 18 is accommodated within a vertical elongate slot or apeiture 19 which is fonned within the sub- frame 7. A mechanism (not shown) is provided for selectively adjusting the position pin 18 within the elongate apeiture 19, thus enabling the front part of the sub-frame 7 to be raised or lowered, adjusting the position of the squab 6 of the seat. The upper-most comer of the triangular connecting plate 14 is pivotally connected by means of a pivot 20 to a generally elongate kinetic energy absorbing anangement 21, the other end of which is connected, by means of a pivot pin 22, to the caniage 5 at a position adjacent the upstanding triangular lug 1 1. The triangular connecting plate thus has three pivot axes which are located at the comers of a notional triangle. In this embodiment the invention, the kinetic energy absorbing means comprises a cylinder 23 accommodating a piston, the piston having a piston shaft 24. The cylinder may contain a viscous fluid, and the piston may be provided with a apeiture therethrough. However, as will become clear, many different types of kinetic energy absorbing device may be used. It is to be appreciated that in the event of a rear impact to a motor vehicle in which the described seat is mounted, the floor pan of the vehicle will move forwardly, thus moving the rail 2 and the caniage 5 forwardly. Consequently the sub-frame 7 and the squab 6 of the seat will begin to move forwardly, tending to provide a forward acceleration to the occupant 10 of the seat. The torso of the occupant of the seat will have substantial inertia, and consequently the torso of the occupant of the seat will effectively impart a substantial relative rearward force to the back of the seat. In the described embodiment this will tend to cause the seat to pivot about the pivot axis defined by the pivot pin 12 canied on the lug 5, with the front part of the frame moving upwardly. Consequently the seat will tend to pivot towards the position shown in Figure 3. It can be seen that as the seat pivots, the lever ami 17 is drawn upwardly with the sub-frame 7, thus tending to rotate the triangular plate 14 about the pivot axis 15. This moves the pivot axis 20 of the triangular plate 14 generally towards the pivot axis 22 to which the kinetic energy absorber 21 is connected, thus compressing the kinetic energy absorber 21 so that the kinetic energy absorber 21 absorbs kinetic energy. It is to be noted that the combination of the lever arm 17 and the triangular plate 14 acts as a gearing anangement in that the movement of the pivot pin 18 caused by the upward movement of the sub-frame 7 is much greater than the consequent movement of the pivot pin 20 on the triangular plate 14. The gearing an angement thus provides a mechanical advantages. It is, of course, the movement of the pivot pin 20 on the triangular plate 14 that is actually resisted by the kinetic energy absorber. Thus the gearing anangement constituted by the combination of the lever ami 17, and the pivotally mounted plate 14 enables the use of a relatively small kinetic energy absorber. It is to be noted that in the described embodiment, the kinetic energy absorber 21 is mounted beneath the squab of the seat and thus does not obstruct the occupant of the seat in any way. The kinetic energy absorber does have a certain length, and is conveniently mounted to be substantially horizontal beneath the squab of the seat. Whilst one embodiment has been described with reference to Figures 1 to 3, in an alternative embodiment of the invention, as shown in Figure 4, a different fonn of kinetic energy absorber is utilised. In the embodiment of Figure 4; the various components of the seat 1, rail 2, caniage 3 and sub-frame 7 that are the same as in the embodiment described with reference to Figures 1 to 3, are identified with the same reference numerals, and will not be re-described. In the embodiment of Figure 4, the kinetic energy absorber comprises a metal plate 3 1 of elongate arcuate fonn, having one end pivotally connected by the pivot 20 to one comer of the triangular plate 14, and having the other end pivotally connected by means of a pivot 32 to a triangular mounting lug 33 that is securely connected to the caniage 5. The arcuate element 31 is provided, substantially at its mid point, with a substantially "V"-shaped notch, recess or cut-out 34 on the inner edge of the arc. This provides an area of relative mechanical weakness. The components will occupy their illustrated position when the seat is in its ordinaiy state. In the event that a rear impact should arise, there will be a tendency, in the manner described above, for the sub-frame 7 to pivot about the axis defined by the pivot pin 12, with the front part of the sub-frame 7 rising. This again will cause the gearing anangement constituted by the lever ami 17 and the triangular plate 14 to pivot about their pivotal connections towards the condition shown in Figure 3. As the gearing anangement constituted by the triangular plate 14 and the lever aim 17 pivot, so the arcuate member 3 1 will be defoimed, with the ends of the arcuate member 31 being driven towards each other. The main deformation will occur in the region adjacent the "V'-shaped cut-out 34. It is to be observed that in this embodiment, the kinetic energy absorbing element is again located beneath the sub-frame 7 of the squab of the seat, and again a gearing or mechanical advantage is provided, by the triangular plate 14 and the lever aim 17, to enable a relatively small kinetic energy absorbing element to be utilised.

Claims: CLAIMS: 1. A vehicle seat, the seat comprising a support stnicture located beneath the seat, and a squab located above the support stnicture, the seat further including a back-rest extending substantially upwardly from the rear part of the squab of the seat, there being means pivotally connecting the rear part of the squab of the seat to the support structure, to peimit the rearward tilting of the back-rest of the seat with a simultaneous upward tilting of the squab of the seat, there being a kinetic energy absorbing means adapted to absorb kinetic energy when the seat executes the tilting movement, the kinetic energy absorbing means being located beneath the squab of the seat and having one end thereof connected to one element of a pivotal linkage, the pivotal linkage extending between the support stnicture and a forward part of the squab of the seat. 2. A seat according to Claim 1 wherein the support stnicture comprises a caniage slidably mounted along rails provided on the floor of the vehicle. 3. A seat according to Claim 1 or 2 wherein the pivotal linkage comprises two elements, one element being pivotally connected to the support stnicture, and also pivotally connected to the other element, the other element being pivotally connected to the squab of the seat. 4. A seat according to Claim 3 wherein the said one element defines three pivot points which are located at the co ers of the triangle, one pivot point being connected to the support stnicture, a further pivot point being connected to the other pivot element, and the third pivot point being connected to the kinetic energy absorbing means. 5. A seat according to any one of the preceding Claims wherein the kinetic energy absorbing means has one end thereof connected to the support stnicture. 6. A seat according to any one of the preceding Claims wherein the kinetic energy absorbing means comprises a piston and cylinder device. 7. A seat according to any one of Claims 1 to 5 wherein the kinetic energy absorbing means comprises a metallic plate of arcuate fonn. 8. A seat according to Claim 7 wherein the metallic plate of arcuate fonn is provided with a notch or recess fonned in the inner edge of the arc to provide a region of mechanical weakness. 9. A seat according to any one of the preceding Claims in which the point of pivotal connection between the support stnicture and the rear of the squab of the seat, and the point of pivotal connection of the linkage and the front part of the squab of the seat are adjustably positionable relative to the squab of the seat to permit an adjustment of the position or orientation of the squab of the seat.

Inventors: LINDBLAD KARL-GUNNAR, SVANTESSON ANDERS, LINDBLAD, KARL-GUNNAR, SVANTESSON, ANDERS
Applicants: AUTOLIV DEV, LINDBLAD KARL GUNNAR, SVANTESSON ANDERS, AUTOLIV DEVELOPMENT AB, LINDBLAD, KARL-GUNNAR, SVANTESSON, ANDERS
Application year: 2000
Main classification: B60N2
IPC codes: B60N2