Energy absorbing bumper system

A bumper apparatus for a vehicle comprising:

• an elongated container having a volume containing a compressible gas,
• an elongated impact receiving portion of the container wall being flexible under impact and shaped to define a substantial section of said container volume in the unflexed condition and to reduce the container volume in the flexed condition,
• and another portion of said container wall being rigid and shaped to define a substantial concave section of said container volume of more than 25% of said flexible wall volume, said concave section having generally the same length and width as said flexible wall section,
• said rigid wall portion being substantially rigid under impact and flection of said flexible wall portion so as not to change substantially the rigid wall section of said container volume,
• means for interconnecting said flexible and rigid sections to transmit fore and aft tension forces from said flexible wall portion in line to said rigid wall concave section and to permit substantially free passage of the compressible gas from the flexible section to the rigid section upon impact so that the gas is at substantially the same pressure in the rigid section as in the flexible section at all times during impacts on said impact wall at speeds within the design impact velocity range of the apparatus,
• and means for attaching said rigid wall section to the exterior of a vehicle with the flexible section projecting therefrom as a bumper therefor,
• whereby upon impact the rise in the gas pressure in said container is limited as impact energy is absorbed by gas compression.