Vehicle seat assembly

Claim 2

A seat assembly according to claim 1, wherein the retaining means is secured to the back rest frame at a position substantially above the centre of the area of the back rest unit which supports the back of an occupant.

Claim 3

A seat assembly according to claim 1 or 2, wherein the tightening means comprises energy absorbing means (16,102) adapted, when the seat assembly is subjected to a force in excess of the predetermined magnitude, to allow the back rest unit (40) to move relative to the seat unit (10) and to absorb energy produced by the force on the back rest unit.

Claim 4

A seat assembly according to claim 3, wherein the energy absorbing means is adapted to allow the back rest unit to move in a plane substantially parallel to the plane of the seat frame.

Claim 5

A seat assembly according to claim 3 or 4, wherein the support means comprises two channels (60) disposed substantially parallel to the seat frame, each secured to a respective side of the seat frame, and a slide member (62) slidably received in each channel and pivotally connected to the back rest frame via a pivot (78); the energy absorber comprising a pair of spaced rollers (74,75) secured to the seat frame and a strap member (70) having one end secured to the slide member and another end portion bent around the spaced rollers in a serpentine configuration, the strap member being adapted to maintain the back rest unit in the rest position during normal vehicle operating conditions and to be drawn through the rollers to allow the slide member and the back rest unit to move relative to the seat unit when the back rest unit is subjected to a force in excess of the predetermined magnitude.

Claim 6

A seat assembly according to claim 3 or 4, wherein the support means (104) comprises a pair of links (102) each pivotally connected at one end to the back rest frame via a respective pivot (104) and at a second end to a fixed support (105); the energy absorber (16) comprising a pair of spaced rollers (74,75) secured to the seat frame, a third roller (110) secured to the seat frame remote from the back rest unit, a cable (108) having one end connected to the back rest unit and passing around the third roller and a strap member (70) having a first strap end secured to a second end of the cable and a second strap end bent around the spaced pair of rollers in a serpentine configuration, the strap member being adapted to maintain the back rest unit in the rest position during normal vehicle operating conditions and to be drawn through the spaced pair of rollers to allow the links to pivot and the back rest unit to move relative to the seat unit when the back rest unit is subjected to a force in excess of the predetermined magnitude.

Claim 7

A seat assembly according to claim 1, 2, 3 or 4, wherein the tightening means (16,102,140) includes a movable member (146) connected to the retaining means and means for effecting movement of the movable member to tauten the retaining means when the back rest unit is subjected to a force in excess of the predetermined magnitude.

Claim 8

A seat assembly according to any preceding claim, wherein the retaining means comprises a wire (20) lying along the sides of the seat frame and of the back rest frame, the wire becoming taut and forming a triangle with the back rest frame and seat frame when the back rest unit is subjected to a force in excess of the predetermined magnitude.

Claim 9

A seat assembly according to claim 8, wherein the wire (20) is a nylon-coated braided metal wire.

Claim 10

A seat assembly according to claim 8 or 9, wherein the wire passes through a tube (c) in the back rest frame.

Claim 11

A seat assembly according to claim 8, 9 or 10, wherein the seat unit and back rest unit each include a cushion and a trim cover, the wire being located beneath the trim covers when the back rest unit is in the rest position.