1. Field of the Invention
The present invention relates to an airbag apparatus which is installed on a vehicle and is adapted to be deployed and inflated between the vehicle and an occupant thereof for protection of the occupant when an impact of a predetermined value or greater is applied to the vehicle when the vehicle is involved in a collision.
2. Related Art
Conventionally, as an airbag for the driver's seat, there is proposed an airbag apparatus described in Patent Publication No. WO 2005/044643A, for example. The airbag apparatus described in WO 2005/044643A includes an inflator functioning as a gas generator and an airbag and is designed to be deployed and inflated momentarily by the pressure of a gas injected from the inflator when an impact of a predetermined value or greater is applied to a front end of the vehicle when the vehicle is involved in a collision. Namely, in this airbag apparatus, the airbag is brought into abutment with an annular rim portion of a steering wheel so as to be deployed and inflated between the steering wheel and an occupant (the driver) seated in the driver's seat when the airbag is deployed and inflated. In addition, when the occupant is captured by the airbag to press the bag toward the front of the vehicle due to the vehicle being involved in a collision, the airbag is not only stopped and received but also is given a reaction force directed to the rear of the vehicle by the rim portion, so that the occupant is protected by the airbag.
Incidentally, in recent years, steer-by-wire type steering systems (steering wheels) which do not use the column shafts draw attentions. In the steering systems like this, there occurs a case where in place of a normal steering wheel in which a rim portion is formed into an annular shape, an irregular steering wheel is used in which part of a normally annular shaped rim portion is open (hereinafter, referred to as a “irregular steering wheel”). In this irregular steering wheel, when looked about in a radial direction from a pad portion where an airbag apparatus is installed, it appears that part of the rim portion is open. In addition, as the irregular steering wheels, an irregular steering wheel is known in which a rim portion is made up of a pair of left and right grip portions which are each formed into a minor arc and the overall shape of the steering wheel including both the grip portions and a connecting portion which connects both the grip portions together is formed into substantially an H-shape as viewed from the top.
In the event of the irregular steering wheel like this, however, when an airbag is deployed and inflated between both the grip portions (namely, at an opening portion of the rim portion), the airbag needs to obtain a reaction force (a reaction force directed to the rear of a vehicle) which is given thereto when restraining (protecting) the occupant by any other means than the rim portion.