1.  Technical Field
The present invention relates to an a pedestrian airbag apparatus, which is arranged near a rear end of a hood panel and has an airbag adapted to cover a part extending from an upper surface of a cowl, which is arranged on a rear side of the hood panel, to front surfaces of left and right front pillars upon completion of inflation. 
2.  Background Art
Conventionally, as a pedestrian airbag apparatus, which has an airbag including a generally rod-shaped transversal inflation portion extending substantially along a left and right direction to cover an upper surface of a cowl and two longitudinal inflation portions extending rearward from both ends of the transversal inflation portion to cover front surfaces of left and right front pillars, one is known in which the airbag is folded by roll-folding to roll a region of the transversal inflation portion, except for a front edge section thereof which is an upstream section in a stream of an inflation gas discharged from an inflator, from a distal end of the longitudinal inflation portions toward a lower surface side, and then by wrapping the region of the upstream section of the transversal inflation portion around the roll-folded section (e.g., see JP-A-2006-069291). 
According to the conventional pedestrian airbag apparatus, in a state where the folded airbag is received in a case, the upstream section isolates an upper wall portion, which is adapted to be arranged on an upper surface side upon completion of inflation, from a lower wall portion, which is adapted to be arranged on a lower surface side, and also is arranged to cover an upper side and a rear side of the roll-folded section disposed therebetween.  At initial inflation, the upstream section of the transversal inflation portion is inflated as the inflation gas is flowed thereinto, and at the same time, pushes out the roll-folded section from a protrusion opening of the case. 
However, in the conventional pedestrian airbag apparatus, because the transversal inflation portion is folded by roll-folding all the region thereof, except for the upstream section, there is a problem in that the roll-folded section is interfered with wipers, which is arranged to protrude from the cowl arranged on the rear side of the storage portion, and thus does not be quickly deployed, when, at initial inflation of the airbag, the upstream section is inflated as the inflation gas from the inflator is flowed thereinto and thus pushes out the roll-folded section from the storage portion. 
Accordingly, in order to solve the above problems, an object of the present invention is to provide a pedestrian airbag apparatus, in which an airbag can be quickly and stably inflated.