Front airbag with hollow portion

1. An airbag, which is folded and accommodated in front of an occupant seated on a seat in a vehicle and is configured to allow expansion gas to flow inside and be developed and expanded so as to protrude from an accommodation part toward a rear side to be able to protect the occupant, the airbag comprising:

a bag main body configured to be expanded by inflowing expansion gas into the inside; and

a plurality of regulating units configured to regulate an expansion completed shape of the bag main body, wherein:

the bag main body has an expansion completed shape as a substantially square cylindrical shape, where a hollow portion which penetrates substantially along a left-right direction is provided and a circumference of the hollow portion is surrounded by an upper expansion portion and a lower expansion portion arranged substantially along a front-rear direction on both upper and lower sides and a front expansion portion and a rear expansion portion arranged substantially along an up-down direction on both front and rear sides, and the rear expansion portion arranged on an occupant side when expansion is completed is defined as an occupant protection portion capable of protecting the occupant and a mounting portion to be attached to an accommodation part side is arranged on a front end side when the expansion is completed;

the regulating units are arranged at a plurality of horizontally symmetrical locations centered on a center of the bag main body on a left-right directional side and each of the regulating units is configured to straddle the hollow portion when viewed from a lateral side in the left-right direction and at least an upper edge side and a lower edge side are connected to a bag main body side; and

the upper expansion portion is configured such that a part on the front end side communicating with the mounting portion and the front expansion portion has a narrow width in the left-right direction and a part on the rear end side communicating with the occupant protection portion has a wide width in the left-right direction.

2. The airbag according to claim 1 , wherein

each of the regulating units is configured to connect a front edge side and a rear edge side to the bag main body side in addition to the upper edge side and the lower edge side.

3. The airbag according to claim 2 , wherein

each of the regulating units is configured as a closing panel whose peripheral edge is connected to the bag main body side over an entire circumference so as to close the hollow portion.

4. The airbag according to claim 3 , wherein

the closing panels are arranged at two locations so as to close both left and right end sides of the hollow portion.

5. The airbag according to claim 4 , wherein:

in the bag main body, an exhaust hole capable of discharging the expansion gas flowing into the bag main body to a hollow portion side is formed in an inner peripheral panel portion forming a peripheral wall of the hollow portion on an inner peripheral surface side; and

in the bag main body, an area surrounded by the inner peripheral panel portion and the closing panel is configured as a gas storage portion.

6. The airbag according to claim 5 , wherein

the exhaust hole is arranged in an area forming a front surface side of the occupant protection portion in the inner peripheral panel portion.

7. The airbag according to claim 5 , wherein

an intake hole portion capable of taking in outside air into the gas storage portion when the bag main body is developed and expanded is formed on at least one of the left and right closing panels.

8. The airbag according to claim 7 , wherein

the intake hole portion is provided with a check valve mechanism capable of suppressing gas discharge to the outside.