Patent ID: 7712768

Claim:
A side curtain air bag, which includes chambers expanded by gas supplied from a gas generator, and expands and develops into a curtain shape along a side part of a vehicle so as to protect vehicle occupants, the side curtain air bag comprising: at least one primary chamber respectively defining an aperture that provides fluid communication between the primary chamber and the gas generator, the primary chamber being expandable by gas supplied by the gas generator so as to protect an occupant; at least one secondary chamber immediately adjacent to the primary chamber and defining an opening that provides direct fluid communication between the primary chamber and the secondary chamber so that the secondary chamber is expandable by receiving the inflow of gas directly from the primary chamber, the aperture and the opening being sized such that the aperture is substantially larger than the opening so that the secondary chamber begins to substantially expand and develop after the primary chamber is approximately fully expanded and developed by gas from the gas generator, and when the gas is generated by the gas generator, high pressure is applied initially to the primary chamber, whereas the secondary chamber gradually increases in pressure to be about the same as pressure of the primary chamber; and at least two tethers, each tether having one end attached to the side curtain air bag at a joint end and the other end attached to a vehicle at a fixation end, wherein, when the side curtain air bag is expanded and developed, the primary chamber and the secondary chamber are arranged such that a portion or all of the primary chamber and a portion or all of the secondary chamber respectively overlap a virtual band, the virtual band being formed along a virtual line connecting the respective joint ends of the at least two tethers, the virtual band defining a region where tension is applied across the side curtain air bag when the primary chamber is approximately fully expanded and developed and the secondary chamber begins to substantially expand and develop.