During a collision with another moving vehicle or a crash with a static vehicle or structure the seat of a car involved in the collision experiences substantial forces transmitted through a chassis of the car to the base of the seat and subsequently to a back support of the seat. Forces may also be transmitted to the back support of the seat by unsecured objects located in the rear of the car. These objects continue moving forward as a result of their own momentum when the vehicle suddenly stops. Unsecured objects in the rear of a car are potentially lethal and it is estimated that the weight of an unsecured child of 20kg rises to approximately 1000kg during a head on collision at 50 km/h. In addition to unsecured objects bombarding the back support of a seat, the back support's own momentum urges the support forward during a collision.

The back support of the seat is connected at one end to the base of the seat while the other end of the back support housing the headrest is free to move. The forces transmitted to the back support of the seat and the base of the seat during a collision cause significant movement of the seat. This uncontrolled movement can by itself cause serious injuries to passengers and can also aggravate or amplify other injuries sustained by passengers as a result of contact with other internal parts of the vehicle during a collision.

It is an object of the present invention to limit the movement of the back support of the seat of a motor driven vehicle during a collision in order to negate the risk of injuries caused by such movement and to prevent further aggravation and/or amplification of other injuries sustained by passengers during a collision.

Accordingly the present invention provides a safety device for use with seats installed in motor driven vehicles characterised in that the safety device comprises an adjustable element having at least two ends and being mountable adjacent a lateral edge of a seat between a base and a back support of the seat, a guide means extending longitudinally along the lateral edge of the seat wherein at least one end of the element is movably housed in the guide means, an

actuation means which adjusts the element in response to a signal from a crash-sensor and a locking means preventing the adjusted element from retracting towards its original position.

In one embodiment, one end of the element is movably housed in the guide means in one component and the other end of the element is pivotally mounted on the other component of the seat.

Ideally, the back support defines a guide means which extends between the lower end and the upper end of the back support adjacent the lateral edge of the seat, wherein one end of the element is pivotally mountable on the base of the seat and the other end is movably housable in the guide means.

Preferably, the base defines a guide means which extends between the front end and the rear end of the base adjacent the lateral edge of the seat, wherein one end of the element is pivotally mountable on the back support of the seat and the other end is movably housable in the guide means.

When the element of the safety device has been adjusted by the actuation means in response to a signal from the sensor, the back support is prevented from pivoting about its mounting point on the base of the seat notwithstanding the various forces encountered during a collision. The safety device prevents forwards or backwards motion of the back support.

Ideally, a safety device is mounted adjacent both lateral edges of the seat. This helps to prevent the back support of the seat from rotating or twisting during a collision.

Preferably, the pivotal mounting point and the guide means of the safety device are integrally formed as part of the structural support frame of the base and back support of the seat.

Preferably, the safety device is used with a seat for a motor driven vehicle incorporating a"belt in seat"concept seat belt.

Vehicle seats with integrated belt points"belt in seat"become relatively expensive, as they must fulfil safety demands through the seat design only. They are about three times heavier than conventional seats as one has to dimension the seat sufficiently so that it is strong enough to

maintain its construction. As a consequence of this, the seats become relatively large from a size point of view. The use of this type of vehicle seat has even meant that the floor in the vehicle has to be considerably strengthened as the chassis of the vehicle seat is exposed to and mediates a very large moment on the floor. This is mainly because the upper belt point in the seat back in seats with integrated belt points transfers a large force (up to 10 kN). A safety device incorporated into the structure of the seat will dramatically reduce the size and weight of vehicle seats of this type as the extendible element of the safety device will absorb a substantial amount of the force transferred from the belt points during a collision.

Preferably, the safety device may be incorporated into seats of the type disclosed in International patent application number PCT/SE00/00356, these seats being devised by the inventor of the present invention.

Ideally, when a vehicle seat incorporates a three-point belt where two attachment points are arranged on the floor of the vehicle and where one attachment point is arranged on a B-pillar in a car, a single safety device mounted on the side of the seat distal from the B-pillar prevents the back support of the seat from twisting during a collision in response to its own momentum thereby reducing the forces absorbed by the body when the belt arrests the motion of the body preventing it from continuing in the original direction of travel of the vehicle.

In one embodiment, the adjustable element is a constant length. This reduces the cost of the safety device by using a simple strut.

Preferably, the adjustable element is axially adjustable.

Preferably, the axially adjustable element is telescopic. The telescopic structure minimises the space required for the axially adjustable element during storage under normal conditions and during extension in response to a signal from a crash sensor. The element may be provided in any geometrical form and may be cylindrical or non-cylindrical.

In another embodiment, the axially adjustable element is provided by a cylinder, piston and piston rod.

Preferably, the cylinder is pivotally mounted to a component of the seat and the free end of the piston rod is movably housed in the guide means of the other component.

In one embodiment, the axially adjustable element extends along a straight linear axis. A straight linear extension facilitates the use of standard parts thereby reducing design and manufacturing costs.

In another embodiment, the axially adjustable element extends along a curved linear axis. A curved linear extension allows the element to extend out and away from passengers reducing the risk of incidental injury to passengers caused by extension of the safety apparatus during a collision.

In this embodiment, each external longitudinal surface of a component part of the element has the same form as the internal longitudinal surface of the surrounding component part in order to allow curved linear extension.

In another embodiment, the adjustable element is provided with a pivot joint between its ends dividing the element into two sections allowing the element to adopt a non-linear configuration.

Preferably, when the adjustable element includes a pivot joint, the actuation means is mounted between the seat and the element.

Preferably, the actuation means is mounted between the pivot joint and the seat.

Optionally, the actuation means is pivotally mounted on either section of the element.

In one embodiment, the actuation means is incorporated into the adjustable element.

In another embodiment, the actuation means is incorporated into the guide means.

Preferably, the actuation means acts on end of the adjustable element mounted in the guide means adjusting the element in response to a signal from a crash sensor.

Optionally, the actuation means is operated by mechanical, pneumatic, hydraulic, electrical or pyrotechnical means.

Preferably, the mechanical actuation means is provided by a spring.

Ideally, the spring is a pretensioned helical spring.

Ideally, the actuation means applies large forces to the element to provide a rapid adjustment of the element in response to a signal from the sensor.

Preferably, when two safety devices are installed, they are both adjusted simultaneously in response to the same signal from the sensor.

Preferably, the actuation means adjusts the element in stages whereby completion of one stage signals the actuation means to start the next stage.

Ideally, the locking means is activated after each individual stage. This prevents the forces transmitted from the back support of the seat to the element overcoming the force transmitted by the actuation means to the element and will prevent retraction of the element beyond the last locked position during a collision.

Ideally, the locking means is an integral part of the adjustable element. The forces acting on the back support of the seat are transmitted along the element therefore it is effective to have the locking means formed as part of the element.

In another embodiment, the locking means is an integral part of the guide means.

In a particularly preferred embodiment, the locking means is provided on the guide means and the adjustable element.

Preferably, the axially adjustable element is locked at predetermined locations along its longitudinal axis.

In one embodiment, the locking means is provided by one way valves mounted at discrete locations along the longitudinal surfaces of component parts of the element formed for relative movement, the valves having a closed position within the surface of the component in which they are housed when the section of the surface housing the valve is in contact with the surface of an adjacent component and an open position where the valves are free to extend out from the surface of their component when the section of the surface in which the valves are housed is contacted by no other surface, the valves allowing movement of the component parts in the direction of extension of the element and preventing component parts from travelling in the opposite direction or direction of retraction of the element.

Preferably, the valves are operated by mechanical, pneumatic, hydraulic, electrical or pyrotechnical means.

Ideally, the valves are actuated by pretensioned springs.

Preferably, a sensor is mounted in the front, rear, sides or centre of the motor driven vehicle or any combination thereof. Sensors at different locations of the vehicle activate the safety device in response to impacts at different positions increasing the safety of passengers in the vehicle.

Preferably, simultaneous adjustment of a pair of safety devices mounted on both lateral sides of a vehicle seat reduces lateral movement of the passenger during a collision. This further reduces the risk of injury to the passenger during a collision, especially from the side.

Ideally, the element is designed to provide the greatest resistance to movement of the back support of the seat. The design of the element also controls the location and design of the guide means.

Preferably, the design of the element accounts for the presence of a large unsecured adult in the rear of the vehicle impacting on the back support of the seat during a collision.

Ideally, the element extends without contacting the passenger sitting in the seat.

In another aspect of the invention, at least one end of at least one element of the safety device is provided with an adjustable mounting device facilitating lateral displacement of the end of the element from the lateral edge of the seat.

Ideally, each end of each element is provided with an axially adjustable mounting device.

In one embodiment, an end of the element mounted in the back support of the seat adjacent a door of the vehicle is laterally extendable to contact the b-pillar and the end of the element mounted in the base of the seat adjacent the door of the vehicle is laterally extendable to contact the corresponding portion of the coachworks of the car after the elements have been adjusted into a crash position.

Preferably, an end of the element mounted in the base of the seat adjacent the raised central portion of the floor is laterally extendable to engage the raised central portion after the element is adjusted into the crash position. When the adjustable mounting devices are designed to engage other structural components of the automobile, they are fitted with sensors to indicate that the adjustable element has reached a crash position before their actuation means laterally extends them from the lateral edge of the seat.

In one embodiment, the head rest of the seat pivots forward in response to a signal from the crash sensor to arrest/cushion rearward motion of the head in a front or rear collision.

Ideally, an airbag is provided in the lateral edge of a seat and is deployed in response to a signal from an airbag sensor indicating that the ends of the adjustable element have adopted a predetermined position. The predetermined position is selected so that the airbag will not come into contact with the adjustable element during deployment.

The invention will now be described with reference to the accompanying drawings, which are given by way of example only and which show seven embodiments of a safety device for use with seats installed in motor driven vehicles in accordance with the invention. In the drawings: Figure 1 is a perspective view of a first embodiment of safety device in accordance with the invention;

Figure 2 is a perspective view of a second embodiment of safety device in a storage position; Figure 3 is a perspective view of the safety device of Figure 2 in an extended position; Figure 4 is a perspective view of a third embodiment of safety device in a storage position; Figure 5 is a is a perspective view of the safety device of Figure 4 in the extended position; Figure 6 is a perspective view of an extendible element having a locking mechanism; Figure 7 is a section view of a fourth embodiment of safety device formed for curved linear extension; Figure 8 is a is a perspective view of a fifth embodiment of safety device ; Figure 9 is a front elevation view of a sixth embodiment of safety device mounted on each lateral edge of the seat ; and Figure 10 is a perspective view of a seventh embodiment of safety device.

Referring to the drawings and initially to Figure 1 there is shown a safety device indicated generally by the reference numeral 1 for use with a seat 2 installed in a motor driven vehicle (not shown). The safety device 1 has a pair of telescopic elements 3 having two ends 4 and 5 mounted between a base 6 and a back support 7 of the seat 2 adjacent lateral edges 8 and 14.

A guide 9 extends along the lateral edges 8,14 of the seat 2 and both ends 4,5 of the telescopic elements 3 are movably housed in the guide 9. An actuator (not shown) is connected between a crash-sensor 12 and the telescopic element 3 and the crash sensor is mounted on any combination of the front, rear, side or centre of the vehicle. A locking mechanism (see Figure 5) is formed as an integral part of the element 3 preventing the extended element 3 from retracting during a collision. A locking mechanism may also be included in the guide 9.

In the drawings and the detailed description of Figures 2,3, 4,5, 8 and 10 identical parts of the safety device 1 and the seat 2 have been designated identical reference numerals to those used to describe the corresponding parts of Figure 1. Referring to the drawings and now to Figure 2 the back support 7 includes a guide 9 which extends between the lower end 10 and the upper end 11 of the back support 7 adjacent the lateral edge 8 of the seat 2. One end of the element 4 is attached on a pivotal mounting point 13 on the base 6 of the seat 2 and the other end 5 is housed in the guide 9. The element 3 is shown in the storage position.

Referring now to Figure 3, a second telescopic element 3 has been mounted adjacent the second lateral edge 14. Both of the elements 3 have been extended in response to a signal from crash sensor 12. In Figure 4, a second orientation of the safety device 1 of Figures 2 and 3 is shown. In this orientation, the base 6 has a guide 9 extending between the front end 31 and the rear end 32 of the base 6 adjacent the lateral edge 8 of the seat. One end 4 of the telescopic element 3 is attached about a pivot point 33 on the back support 7 of the seat 2 and the other end 5 is housed in the guide 9. The telescopic element 3 is in a storage position. In Figure 5, the safety device 1 of Figure 4 is shown with the telescopic element 3 in an extended position in response to a signal from the crash sensor 12. It will of course be appreciated that a second element 3 could be attached to the other lateral edge 34 of the seat 2 as shown in Figures 1 and 3.

Referring to the drawings and now to Figure 6 there is shown a telescopic element indicated generally by the reference numeral 53 having an integrally formed locking mechanism. The locking mechanism is provided by one-way valves 54 located along the longitudinal surfaces 55 of component parts 56 of the element 53. The valves 54 are closed when the section of the surface 55 housing the valve 54 is inside the surrounding component 56. The valves 54 are open when the sections of the surface 55 in which the valves are housed are outside the surrounding component part 56. In use, the valves 54 extend into an open position under the influence of a biasing member (not shown) once their surface 55 extends out of their surrounding component part 56 in response to a signal from the crash sensor 12. The valves 54 allow movement of the component parts 56 in the direction of extension of the element 53 and prevent component parts 56 from travelling in the opposite direction or direction of retraction of the element 53. The element 53 has an attachment 57 at one end 58 for pivotally mounting the element 53 about the seat 2 in conjunction with a corresponding attachment 13 located on the seat 2. The element 53 also has an attachment 59 at the other end 52 for

housing the element in the guide 9 in conjunction with a corresponding attachment (not shown) in the guide 9.

Referring to the drawings and now to Figure 7, there is shown a section view of an element indicated generally by the reference numeral 63 which extends along a curved linear axis 64.

External longitudinal surfaces 65 of surrounded component parts 66 of the element 63 have the same form as the internal longitudinal surfaces 67 of the surrounding component parts 66.

In use, a curved linear extension allows the element 63 to extend out and away from a passenger sitting in the seat 2 reducing the risk of incidental injury to passengers during a collision.

In Figure 8 there is shown a safety device indicated generally by the reference numeral 1 for use with a seat 2 installed in a motor driven vehicle (not shown). The safety device 1 has an adjustable element 81 divided into two sections by a pivot joint 82 and having two ends 4 and 5 mounted between a base 6 and a back support 7 of the seat 2 adjacent lateral edge 8. It will of course be appreciated that an element 81 may also be mounted on lateral edge 14. A guide 9 extends along the lateral edges 8, 14 of the seat 2 and both ends 4,5 of the element 81 are movably housed in the guide 9. An actuator 83 is connected between a crash-sensor 12 and element 81 and the crash sensor is mounted on any of the front, rear, side or centre of the vehicle. A locking mechanism is formed between the pivot joint 82 and the two sections of the element 81. The two sections of the element 81 are locked at predetermined stages of the actuation preventing the element 81 from collapsing during a collision. It will of course be appreciated that the element 81 may be mounted as shown in any of the configurations of Figures 2 to 5.

Referring to the drawings and to Figure 9, there is shown a front elevation view of a seat 2 having an adjustable element 91 mounted on each lateral edge of the seat. Mounting points 92 of the elements 91 include axially adjustable mounting devices 93 for adjusting the mounting points 92 laterally from the lateral edges of the seat 2. The ends of the elements 91 mounted in the back support 7 of the seat 2 adjacent the doors of the vehicle are extended to contact a b- pillar 94 and the ends of the element mounted in the base of the seat adjacent the door of the vehicle are extended to contact the corresponding portion of the coachworks of the car 96.

Ends of the elements 91 mounted in the base 6 of the seat 2 adjacent the raised central portion 97 of the floor are extended to engage the raised central portion 97. When the axially

adjustable mounting devices 93 are designed to engage other structural components of the automobile, they are fitted with sensors to indicate that the adjustable element has reached a crash position before their actuation means laterally extends them from the lateral edge of the seat 2.

Referring to the drawings and finally to Figure 10, there is shown a perspective view of a seat 2 with a safety device 1 using an element 103 of constant length. The actuator acts on the ends 4,5 of the element 103 in response to a signal from a crash sensor 12 and the ends 4 and 5 are moved simultaneously along the guide 9 until they adopt a predetermined crash position. The locking means is provided on both guides 9.

It will of course be understood that the invention is not limited to the specific details as herein described, which are given by way of example only, and that various alterations and modifications may be made without departing from the scope of the invention as defined in the appended claims.