Air bag device for cars

Claim 1

An air bag device, comprising: a container for being charged with a gas under pressure; said gas container including an opening portion communicating with an air bag; a pressing lid; a frangible lid disposed between said pressing lid and said gas container; said opening portion of said gas container being tightly sealed by said frangible lid; said pressing lid being provided in an inlet portion of a passage connecting said opening portion of said container with an inlet of the air bag; said pressing lid including a body portion having an outside diameter substantially smaller than the diameter of said inlet portion of said passage, such that the outer periphery of said body portion is substantially spaced apart inwardly from said inlet portion so as to define a definite annular space between said body portion of said pressing lid and said inlet portion of said passage; said frangible lid being disposed so as to face said inlet portion of said passage and being supported on only a central part of one surface thereof by said body portion of said pressing lid; said frangible lid having an outer peripheral part facing said annular space around said body portion of said pressing lid; said body portion of said pressing lid being provided with a pressing surface contacting only said central part of said frangible lid which is sufficiently large to prevent fracture of said frangible lid by said gas under pressure only when the pressure of said gas is within a normal range; said outer peripheral part of said frangible lid being partially fracturable when the pressure of said gas becomes abnormally high so as to permit gradual discharge of the high pressure gas through said annular space, with said central part of said frangible lid remaining supported by said body portion of said pressing lid; means for applying pressure to said pressing lid; and impact detecting means for releasing said link mechanism.