GB2377630A

GB2377630A - Vehicle seat safety arrangement

Info

Publication number: GB2377630A
Application number: GB0117299A
Authority: GB
Inventors: Muhammed Ali Narin
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 2001-07-16
Filing date: 2001-07-16
Publication date: 2003-01-22
Anticipated expiration: 2021-07-16
Also published as: GB2377630B; GB0117299D0

Abstract

The vehicle seat 1 has an upwardly inclined seat squab (2, Fig 1), an occupancy sensor 11 and a safety belt 13 with a usage sensor 12. In the event of a signal from accident sensor 10, if the seat is sensed to be occupied but the safety belt is sensed not to be in use, then the seat squab is moved (see arrow 16) from its initial position to a less inclined angle, thereby avoiding the occupant being projected upwardly into the windshield. The seat back may also pivot forward (see arrow 15).

Description

IMPROVEMENTS IN OR RELATING TO A SAFETY ARRANGEMENT THE PRESENT INVENTION RELATES to a safety arrangement and more particularly relates to a safety arrangement in the context of a motor vehicle such as a motor car.

It has been found that an occupant of a front seat in a motor vehicle, such as a motor car, who is not wearing a safety belt, may, in a frontal impact situation, move forwardly in such a way that the head of the occupant hits the upper part of the wind shield. It is believed that a reason for this is that the squab or seat cushion of the vehicle seat is typically inclined upwardly in the manner of a ramp, and this guides the torso of the occupant upwardly and forwardly when the vehicle is subjected to deceleration. If, in contrast, the occupant of the seat were wearing a seat belt this particular situation would not arise, because the seat belt would tend to retain the seat occupant in the vehicle seat. Indeed, if the occupant of the seat is wearing a seat belt, the inclination of the squab or seat cushion is advantageous, because it may reduce or prevent the so-called"submarining effect"in which the lower part of the torso of the seat occupant tends to slide forwardly thus pulling the upper part of the torso downwardly.

The present invention seeks to provide an improved safety arrangement.

According to this invention there is provided a safety arrangement, the safety arrangement comprising a vehicle seat having a safety belt associated therewith, the safety arrangement including an occupant sensor to sense an occupant on the seat and a safety belt sensor to sense operative use of the safety belt, the seat including a squab and a backrest, the squab having an upper surface which, in an initial condition thereof, is inclined upwardly from the rear edge thereof adjacent the backrest to the front edge thereof, the seat incorporating a mechanism operative to adjust the angle of inclination of at least part of the upper surface of the squab so that the angle of inclination may be reduced, the mechanism being enabled when the occupant sensor senses an occupant on the seat and the seat belt sensor senses that the seat belt is not in use, the mechanism being actuable in response to a signal from an accident sensor.

Preferably the occupant sensor is a weight responsive sensor.

Conveniently the seat belt sensor is a sensor mounted in a buckle forming part of a seat belt associated with the seat.

In one embodiment the mechanism is a mechanical mechanism which initially supports the front part of the squab of the seat in an elevated position.

Conveniently the mechanical mechanism is in the form of an over dead centre linkage associated with a piston and cylinder arrangement having a piston movable so as to move the linkage through a"dead-centre"condition.

In an alternative embodiment the mechanism incorporates a permanently inflated chamber provided within the seat squab under at least the front part of

the upper surface of the squab, the chamber being provided with an openable outlet, which is openable in response to said signal from an accident sensor.

Preferably on actuation of the mechanism, the upper surface of the squab moves to a substantially horizontal or downwardly inclined position.

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 I is a diagrammatic side view illustrating a typical vehicle seat showing a situation that can arise if an occupant of the seat is not wearing a seat belt when a frontal impact occurs to the vehicle in which the seat is mounted ; FIGURE 2 is a view corresponding to Figure 1 but illustrating one embodiment of a seat forming a safety arrangement in accordance with the invention, showing the seat in an initial position in phantom and showing the seat in a final position in solid lines; FIGURE 3 is a diagrammatic view illustrating a release mechanism forming part of the embodiment illustrated in Figure 2; FIGURE 4 is a diagrammatic side view, partly in section, of an alternate vehicle seat for use in a safety arrangement in accordance with the invention in a first condition;

FIGURE 5 is a view of the seat of Figure 4 illustrating the seat in a second condition, and FIGURE 6 is a view of the seat of Figures 4 and 5 located in a motor vehicle in an accident situation.

Referring initially to Figure I of the accompanying drawings a vehicle seat 1 forming a safety arrangement in accordance with the invention is illustrated comprising a squab 2 and a back rest 3, the seat 1 being mounted in a vehicle 4 such as a conventional motor car. The upper surface of the squab 2 of the seat is inclined upwardly, the rear edge of the squab, adjacent the backrest, being at a lower level than the front edge of the squab 2. A seat occupant 5 is illustrated, but the seat occupant is not wearing a safety belt.

The situation illustrated in Figuie I is a situation that exists shortly after a frontal impact has occurred to the vehicle 4 in which the seat 1 is mounted.

It is to be appreciated that Figure 1 illustrates an inflating air bag 6, which has emerged from the dashboard 7 of the vehicle. However, the seat occupant is shown in a forward position, since the seat occupant 5 was not initially restrained by any form of safety belt The seat occupant has been guided by the generally inclined squab or seat cushion 2 of the seat I in a forward and upward direction. Whilst the torso of the occupant 5 has engaged in the inflating airbag 6, the head of the occupant has impacted with the windscreen or wind shield 8 of the vehicle.

Figure 2 illustrates a first embodiment of a seat for use in an arrangement in accordance with the invention. Many of the components shown in Figure2 correspond with equivalent components of the prior art arrangement

as shown in Figure 1, which are identified by like reference numerals and which will not be re-described in detail.

The seat 1 of the embodiment shown in Figure 2 initially occupies the position shown in phantom. The forward part of the seat squab or cushion is retained in the elevated position by means of a release mechanism 9. One example of a release mechanism will be described below with reference to Figure 3.

It is to be understood that the release mechanism 9 serves to retain the front part of the seat cushion or squab 2 in the initial elevated position so that the squab or seat cushion 2 has the conventional inclined orientation.

The release mechanism 9 is associated with a first sensor 10 adapted to sense an accident situation. The sensor 10 may be in an appropriate accelerometer. The release mechanism 9 is associated with a second sensor 11 adapted to sense whether the seat 1 is occupied by an occupant 5 or not. The sensor 11 may, as in the present embodiment, comprise a weight sensor located in the squab or seat cushion 2 of the seat, which will provide an output signal when weight is applied to the top of the seat, for example by a seat occupant.

However, the sensor 11 could comprise any alternative suitable form of sensor, such as, for example, an optical sensor.

A third sensor 12 is provided adapted to sense whether a safety belt 13 associated with the seat 1 is in an operative position retaining the seat occupant.

The sensor 12 may, therefore, comprise a sensor associated with a buckle 14 for the safety belt. Alternatively the sensor may sense the length of safety belt withdrawn from the retractor spool associated with the safety belt.

It is to be appreciated that if the seat is occupied by a seat occupant and the safety belt is embracing the occupant, then the release mechanism 9 is not enabled. However, if the seat is occupied and the safety belt is not in use, then the release mechanism 9 is enabled. If the release mechanism 9 is enabled and an accident occurs which is sensed by the sensor 10, the release mechanism is actuated and consequently the squab or seat cushion 2, together with the back rest 3, will move from the initial position as shown in phantom in Figure 2 to a second or final position as shown in solid lines, (as indicated by the arrows 15, 16) with the seat squab moving to a position in which the upper face thereof is no longer inclined but, instead, is substantially horizontal. In such a situation the upper surface of the squab no longer acts as a ramp to guide the seat occupants 5 upwardly, and the seat occupant then moves forwardly in a generally horizontal direction.

Consequently, if the seat occupant is on the seat and is not wearing a safety belt, in the event of a frontal impact the upper surface of the squab or seat cushion 2 moves from the inclined position to a position in which the angle of inclination is reduced such as a horizontal position, and then it is to be expected that, as the seat occupant moves forwardly (being unrestrained by a safety belt) the seat occupant will impinge with the inflating airbag 6 without the head of the seat occupant striking the windscreen 8.

The release mechanism as shown, in Figure 3, may comprise a mechanism in the form of an over dead-centre linkage 20 comprising a lower link 21 having one end pivotally connected 22 to the floor of a vehicle and an upper end pivotally connected 23 to the lower end of the second link 24, the upper end of which is pivotally connected 25 to part of the squab or seat cushion 2. The linkage 20 initially maintains the front part of the squab 2 of the seat in an elevated position. A piston 26 and cylinder 27 arrangement is

provided associated with pyrotechnie charge 28 which, when activated, supplies gas to the piston to move the piston.

Initially the piston engages part of the linkage adjacent the pivotal connection 23 between the lower link 21 and the upper link 24, to maintain the link in the illustrated position in which it supports the squab 2 of the seat with the front part of the squab 2 elevated. When the piston moves, when the pyrotechnic change is activated, the piston moves the pivotal connection 23 through a"dead-centre"condition to a point at which the linkage will simply collapse. A frangible element 29 may be provided to retain the linkage in the illustrated position, the frangible element being adapted to break on actuation of the piston 26 and cylinder 27 arrangement. The piston 26 and cylinder 27 arrangement will be actuated by ignition of the pyrotechnic charge 28 in response to a signal from the accident sensor 10.

Turning now to Figure 4 of the accompanying drawings a further embodiment of the invention is illustrated in which the seat squab or cushion 2 is provided with a permanently inflated chamber 30 located beneath at least the front part of the upper surface of the squab or seat cushion 2. The permanently inflated chamber 30 is provided with an openable outlet or vent 31. The chamber 30 is made of a deformable material that remains gas tight for a long period of time, such as a thin metal sheet, or a sheet of plastics material. Thus, in manufacture of the seat, the chamber 30 is inflated with gas and sealed.

In an accident situation in which the presently described safety arrangement is to be deployed the vent 31 will be opened, thus enabling the inflated chamber 30 to deflate and occupy the condition shown in Figure 5. It is to be noted that the effect of deflating the inflated chamber 30 is such that the upper surface of the squab or seat cushion 2 which, in a condition shown in

Figure 4, was inclined upwardly, is, as shown in Figure 5, inclined downwardly.

The vent 31 may comprise a panel surrounded by a line of mechanical weakness, the panel being connected, by a wire, to a piston and cylinder arrangement associated with a pyrotechnic charge. Movement of the piston will cause the panel to be tom out of the rest of the chamber 30 thus opening the vent 31. The piston and cylinder arrangement will be provided with sensors of the type described with reference to Figure 2 so that the vent is only opened in an accident situation when the seat is occupied by a person who is not wearing a safety belt.

The inflated chamber 30 has been described as being inflated with gas, but in a modified embodiment the inflated chamber may initially contain a liquid, the liquid being able to flow out of the chamber when the vent 31 is opened.

It is to be appreciated that an occupant of the seat shown in Figures 4 and 5 will, in an accident situation, be directed forwardly to engage with an inflating airbag without the head of the occupant striking the windshield of the motor vehicle.

Thus, in the embodiments described above, if the vehicle seat is occupied and if a safety belt is not being worn by the occupant of the seat, when an accident situation is detected, either the release mechanism is released or the inflated chamber is opened to deflate, with effect that the angle of inclination of the upper surface of the squab or seat cushion is adjusted so that the angle of inclination is reduced. Preferably, after the angle of inclination has been adjusted, the squab or seat cushion no longer constitutes an upwardly

directed ramp but instead has a substantially horizontal or even downwardly inclined upper surface.

In the present specification comprises means"includes or consists of and"comprising"means"including or consisting of.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS:

1. A safety arrangement, the safety arrangement comprising a vehicle seat having a safety belt associated therewith, the safety arrangement including an occupant sensor to sense an occupant on the seat and a safety belt sensor to sense operative use of the safety belt, the seat including a squab and a backrest, the squab having an upper surface which, in an initial condition thereof, is inclined upwardly from the rear edge thereof adjacent the backrest to the front edge thereof, the seat incorporating a mechanism operative to adjust the angle of inclination of at least part of the upper surface of the squab so that the angle of inclination may be reduced, the mechanism being enabled when the occupant sensor senses an occupant on the seat and the seat belt sensor senses that the seat belt is not in use, the mechanism being actuable in response to a signal from an accident sensor.

2. An arrangement according to Claim I wherein the occupant sensor is a weight responsive sensor.

3. An arrangement according to Claim I or Claim2 wherein the seat belt sensor is a sensor mounted in a buckle forming part of a seat belt associated with the seat.

4. A safety arrangement according to any one of the preceding claims wherein the mechanism is a mechanical mechanism which initially supports the front part of the squab of the seat in an elevated position.

5. An arrangement according to Claim 4 wherein the mechanical mechanism is in the form of an over dead centre linkage associated with a

piston and cylinder arrangement having a piston movable so as to move the linkage through a"dead-centre"condition.

6. An arrangement according to any one of Claims 1 to 3 wherein the mechanism incorporates a permanently inflated chamber provided within the seat squab under at least the front part of the upper surface of the squab, the chamber being provided with an openable outlet, which is openable in response to said signal from an accident sensor.

7. An arrangement according to any one of the preceding Claims wherein, on actuation of the mechanism, the upper surface of the squab moves to a substantially horizontal or downwardly inclined position.

8. A safety arrangement substantially as herein described with reference to and as shown in Figures 2 and 3 of the accompanying drawings.

9. A safety arrangement substantially as herein described with reference to and as shown in Figures 4 to 6 of the accompanying drawings.

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