1. Field of the Invention
The present invention relates to an airbag system for a steering wheel having an airbag that is folded and housed in a boss part of a steering wheel, which airbag can be unfolded and expand allowing the expansion gas to flow therein.
2. Description of Related Art
Conventionally, the airbag system for a steering wheel has the configurations disclosed in JP-A-6-144136 and JP-A-7-89402. In these airbag systems, an airbag is folded through first and second steps, then the folded airbag is housed. In the first step, superposing an approximate circular vehicle body side wall and a circular driver side wall and unfolding them flatly, then, the regions at the opposite edges in a transverse direction are folded along folded lines in an approximate longitudinal direction so as to bring these regions close to a gas inlet side that is arranged near the center of the vehicle body side wall. In the second step, the regions at the opposite edges in the longitudinal direction of the airbag folded in the first step are further folded along folded lines in the approximate transverse direction so as to bring these regions close to the gas inlet side.
However, in the conventional airbag system for the steering wheel, there is room for improvement in the reduction of the suppress strength of the airbag to a driver when the driver is near the steering wheel upon unfolding and expansion of the airbag.