Patent ID: 7552941

Claim:
An airbag apparatus comprising: an airbag inflatable with inflation gas; an inflator supplying inflation gas to the airbag; a case, housing and holding the airbag and the inflator; and a vent mechanism operated by an actuator exhausting inflation gas filled inside the airbag, the vent mechanism including: a vent opening formed on the case releasing the inflation gas filled inside the airbag; a lid formed on the case to close off the vent opening, the lid being pivotally supported at a periphery of the vent opening by a rotary shaft thereof disposed across the vent opening to rotate about the rotary shaft to open the vent opening, the lid including on one side of the rotary shaft an outward-opening area configured to rotate outward of the case and on an other side of the rotary shaft an inward-opening area configured to rotate inward of the case; and a closing mechanism connected to the actuator and holding the lid to keep the vent opening closed when the actuator is inactive and releasing the lid to open the vent opening upon operation of the actuator, wherein: the vent mechanism includes a plurality of the lids; the lids are arranged in such a relation to an inlet opening of the airbag to admit inflation gas that the lids provide equal areas permitting inflation gas to be exhausted relative to the center of the inlet opening of the airbag at opening the vent opening; the closing mechanism conducts the hold and release of all the lids at the same time; the closing mechanism includes a sliding element disposed on an outer side of the case for sliding movement in parallel with opening planes of the vent openings upon operation of the actuator; each of the lids includes an engaging strip for engagement with the sliding element, the engaging strip being disposed at a leading end of the outward-opening area of the lid facing away from the rotary shaft and located outside of the case; and the sliding element includes slots engageable with the engaging strips; each of the slots having a regulating surface for regulating the engaging strip to keep the outward-opening area of the lid closing off the vent opening before the sliding movement of the sliding element and a guide surface extending diagonally with respect to the opening plane of the vent opening for sliding on the engaging strip to guide the outward-opening area of the lid to open upon the sliding movement of the sliding element.