Air bag device for knee protection

A knee-protecting airbag device for protecting knees of a driver, the airbag device being located below a column cover covering a steering column, the column cover being inclined to rise upward toward a rear in such a manner that the front part of the column cover is located downward while the rear part of the column cover is located upward, the airbag device comprising a folded and housed airbag, wherein:

• upon inflow of an inflation gas, the airbag expands and inflates while rising along a lower surface of the column cover, in a clearance between the column cover lower surface and a driver's knees, thereby covering at least an area from a front side to a rear end vicinity of the lower surface of the column cover;
• when having completed expansion and inflation, the airbag is configured in a generally plate shape extending along the lower surface of the column cover;
• the airbag includes a column cover side wall arranged toward the column cover and a driver's side wall arranged toward the driver at the complete expansion and inflation of the airbag;
• in a flatly developed state where the driver's side wall and the column cover side wall of the airbag are overlaid one on the other, the lateral width of the airbag is greater than the lateral width of a housing area of the airbag;
• the airbag, before being housed in the housing area, is folded through two folding processes:
• a roll-folding step where the airbag is roll-folded from an upper end thereof toward the column cover side wall in order to reduce the vertical dimension of the airbag;
• and a longitudinal folding step for reducing the lateral width of the airbag;
• a lower part of the airbag serves as an unstream portion of the inflation gas whereas the upper part of the airbag serves as a downstream portion of the inflation gas;
• the airbag internally comprises a gas flow regulating member, the gas flow regulating member connecting the column cover side wall and the driver's side wall, and thereby partitioning the upstream portion and downstream portion, and the gas flow regulating member being arranged along the transverse direction of the airbag in such a manner as to provide gas communication holes between a left end and a right end of the gas flow regulating member and a left end inner surface and a right end inner surface of the airbag;
• and
• the gas flow regulating member directs the inflation gas toward both the left direction and the right direction in the upstream portion, and then directs the inflation gas toward the upper part of the airbag as the downstream portion.