Air bag assembly

Claim 1

A lumbar supporting air bag built into a seat back, comprising: a main body consisting essentially of a resilient sheet of synethetic resin sealed together at side edges thereof; port means provided in said main body for introducing air into said main body and for withdrawing air from said main body; a plurality of partitions formed in said sheet, said partitions being aligned substantially colinearly and extending transversely along said main body, said partitions being separated from one another and defining mutually communicating upper and lower horizontal chambers in said air bag; each of said partitions having longitudinally extending elongated holes at the center thereof, wherein opposing edge of said elongate holes separate from each other when air is introdued under pressure into the bag, in such manner that said elongate holes cause said upper and lower chambers to be outwardly expanded; first and second plates sandwiching said air bag, said first plate having a plurality of apertures aligned with said lower chamber, said first and second plates each having a pair of mounting lugs for mounting said plates on said seat back member, said mounting lugs of each pair being equally spaced along a peripheral portion of said first and second plates on a side of said upper chamber opposite from said lower chamber, said pairs of mounting lugs beig aligned with each other when said plates are mounted on said seat back member; a resin sheet on the side of said first plate opposite said air bag, said sheet contacting said lower chamber of said air bag through said aperatures in said first plate, wherein the contacting surfaces between the sheet and said lower chamber of said air bag are joined for supporting the air bag on said plates.