Vehicle safety device

Claim 1

A vehicle safety device including impact bag means inflatable on crash impact for protection of an occupant of a vehicle, a fluid source, and means providing for fluid flow from said fluid source to effect inflation of said impact bag means on crash impact, said impact bag means comprising at least in part a woven stretch fabric having a plurality of threads of stretch yarn extending in at least one direction in juxtaposition for elongation of the woven stretch fabric so that inflating fluid permeability of the woven stretch fabric portion of said impact bag means is increased upon occupant impact against said impact bag means and upon increase of fluid pressure within said impact bag means by enlargement of the openings in said woven stretch fabric portion there of, said woven stretch fabric having substantially instantaneous recovery of at least 70 percent after elongation within the range of differential pressures to which such an impact bag means will normally be subjected so that inflating fluid permeability thereof is decreased upon decrease of fluid pressure within said impact bag means and by dissipation of the forces of occupant impact against said impact bag means by decrease in the size of the openings in said woven stretch fabric portion thereof and having a permeability/pressure curve under impact conditions at a velocity of 30 miles per hour and within the range of differential pressures to which such impact bag means will be normally subjected which substantially conform to the empirical formula lambda 3.7p4 + 20 at differential pressures of substantially 0.25 - 2.45 pounds per square inch gauge and substantially conforms to the formula lambda 80p 40 at differential pressures above 2.5 pounds per square inch gauge, wherein lambda is fabric permeability in terms of cubic feet of fluid flow per square foot per minute and p is the differential pressure of fluid in the impact bag means in terms of pounds per square inch gauge, the openings in said woven stretch fabric being continuously variable in direct relation to fluid pressures within said impact bag means.