Fastener

Abstract

A fastener for an airbag cover, the fastener comprising first and second stringer tapes which are fixed to edges of an opening in the airbag cover. The stringer tapes each have a row of coupling elements mounted thereon, and these link together to connect the stringer tapes. The connection is strong within an area of coupling elements which have been connected, but is easily disengaged from the ends of a region of connected coupling elements. The fastener comprises holding means which hold the tapes together at a predetermined position in the middle region of the fastener. The holding means will release or displace under the force of the airbag expanding. When the airbag expands, e.g. during a car crash, the holding means allows the coupling elements to open, thus opening the fastener and allowing the airbag to expand outside the airbag cover.

What is claimed is:  
     
         1 . A zip fastener having a pair of tapes which are joined by rows of coupling elements mounted on the respective tapes, a point of weakness being provided at a predetermined position along the fastener so that the coupling elements will separate at the point of weakness when a predetermined force is applied to the fastener.  
     
     
         2 . A zip fastener as claimed in  claim 1 , wherein more than one point of weakness is provided along the fastener.  
     
     
         3 . A zip fastener as claimed in  claim 1 , wherein a point of weakness is provided between regions of engaged coupling elements of the fastener.  
     
     
         4 . A fastener comprising first and second stringer tapes, each with a row of coupling elements mounted thereon, such that when the fastener is closed, said stringer tapes are connected to each other by means of said coupling elements, each row of coupling elements comprising a first area and a second area where the coupling elements on the first and second tapes are engaged when the fastener is closed; and holding means for holding said tapes together at a predetermined position intermediate said first and second areas, the holding means being released when a force greater than a predetermined value is applied to the holding means, to allow or cause the coupling elements within the first and second areas to disengage.  
     
     
         5 . A fastener as claimed in  claim 4 , wherein said holding means comprises a pair of sliders, and a stopper is provided to stop the sliders at the predetermined position.  
     
     
         6 . A fastener as claimed in  claim 5 , wherein said holding means comprises linking means to connect said pair of sliders together.  
     
     
         7 . A fastener as claimed in  claim 6 , wherein said linking means is an element separate to each slider, said linking means having first engaging means for engaging with the first slider, and second engaging means for engaging with the second slider.  
     
     
         8 . A fastener as claimed in  claim 4 , wherein said holding means comprises a link which connects the stringer tapes when the fastener is closed.  
     
     
         9 . A fastener as claimed in  claim 8 , wherein said link comprises a connection which is disengaged to open the fastener and re-engaged to re-form the link after it has been disengaged by said force.  
     
     
         10 . A fastener as claimed in claims  8  or  claim 9 , wherein said link comprises a female element and a male element, said female element being engaged with said male element to close the link.  
     
     
         11 . A fastener as claimed in  claim 8  or  claim 9 , wherein said link comprises a projection extending away from the surface of the stringer tapes, whereby said link is disengageable when said force is applied to said projection.  
     
     
         12 . A fastener as claimed in  claim 8 , wherein said link comprises a frangible element which is breakable to disengage the link.  
     
     
         13 . A fastener as claimed in  claim 12 , wherein said link comprises a fused area of stringer tape.  
     
     
         14 . A fastener as claimed in  claim 12 , wherein said link comprises an additional area of tape which is fused onto said stringer tape.  
     
     
         15 . A fastener as claimed in  claim 4 , wherein the force required to release or displace the holding means is less than 400 N, said force being applied to an area of the fastener adjacent to the holding means, in a direction substantially perpendicular to the surface of the stringer tape adjacent to the holding means.  
     
     
         16 . A fastener as claimed in  claim 4 , wherein the force required to release the holding means is greater than 300 N, said force being applied to an area of the fastener adjacent to the holding means, in a direction substantially perpendicular to the plane of the stringer tape adjacent to the holding means.  
     
     
         17 . A fastener for closing an airbag cover, said fastener being as claimed in  claim 4 .  
     
     
         18 . A cover for a motor vehicle seat, comprising an opening for an airbag, and a fastener as claimed in  claim 4 , said fastener being attached to said cover at said opening to close said opening.  
     
     
         19 . A seat for a motor vehicle, said seat comprising a frame, a cover mounted on said frame, an airbag within said frame, wherein said cover comprises an opening for the airbag to expand through when the airbag inflates, and said cover comprising a fastener as claimed in  claim 4 , said fastener being attached to said cover at said opening to close said opening in normal use and to open under the impact of the air bag when the airbag is inflated to allow the airbag to pass through the opening.  
     
     
         20 . A method of closing an opening in an airbag cover, comprising 
 providing two stringer tapes, each comprising a row of coupling elements mounted on an edge of the respective stringer tape;    fixing each stringer tape along an edge of said airbag opening;    closing said coupling elements to join said stringer tapes together; and    providing a weak point at which said tapes will separate under the force of the expanding air bag.    
     
     
         21 . A method as claimed in  claim 20 , wherein said weak point is provided by a frangible or releasable connection