Patent ID: 7481449

Claim:
An airbag device for a driver's seat disposed at an upper part side of a steering wheel by a boss at the center, having, an airbag which is stored after being folded, and spreads and expands when expansion gas is supplied, an inflator for supplying the expansion gas into the airbag, a bag holder for holding the airbag that has been folded, and an airbag cover which covers the airbag that has been folded, and has a door part that opens by a push of the airbag when expanding; wherein, the airbag has a driver-side wall part disposed at the top side and a carbody-side wall part disposed at the bottom side when expansion is completed, each of the parts being in an approximately disk shape, and formed by coupling outer edges of the driver-side wall part and the carbody-side wall part to each other; the carbody-side wall part is in a configuration where a gas opening for inserting the inflator is disposed near the center, and the periphery of the gas opening is made as an attachment region to the bag holder; the airbag is configured to be stored in a manner that, the carbody-side wall part and the driver-side wall part are overlapped and spread flat, and folded so that airbag widths between opposite edge portions of the airbag with the gas opening as a center are reduced, and the airbag is configured to be stored in the upper part side by the boss through a folding process of three steps: a first step, a second step for reducing a width in a direction perpendicular to a direction in the first step, and a third step for reducing the width in the same direction as in the first step; the first step is a step in which the carbody-side wall part and the driver-side wall part are overlapped and spread flat, and opposing edge portions with the gas opening as the center are folded toward the carbody-side wall to be brought close to the gas opening, respectively, such that wound regions are provided and a folding allowance in each of the opposing edge portions remain unfolded to be folded in the third step; the second step is a step in which opposing edge portions with the gas opening as the center are folded toward the driver-side wall part to be brought close to the gas opening, respectively, and the folded regions by the two edge portions each cover approximately half the gas opening; and the third step is a step in which opposing edge portions with the gas opening as the center are folded in such a way to be bent upward toward the driver-side wall, so that bent regions are disposed near two sides of the inflator inserted through the gas opening.