Airbag device

1. An airbag device, comprising:

an airbag that inflates in such a way as to be able to protect an occupant seated in a seat owing to an inflating gas being caused to flow into an interior;

a housing region in which the airbag is housed folded; and

an actuator, which is attached to the housing region side and is of a configuration that causes a coupling member extending from the airbag to be coupled, and controls an inflation aspect of the airbag by causing a state of coupling with the coupling member to be maintained or terminated, wherein

the coupling member is configured of a string-form body having flexibility,

the actuator includes a gas generator configured in such a way as to be able to eject a combustion gas generated by a combustion of an explosive housed in an interior from an ejection port when operating, and

a holder portion around which the coupling member can be wound and held,

the holder portion includes a holding wall portion, which is disposed in such a way as to approximately follow a direction of ejection of the combustion gas from the ejection port and can hold the wound coupling member on an outer peripheral face side, and

a top wall portion disposed in such a way as to close a leading end side separated from the gas generator in the holding wall portion,

and is configured in such a way that a contact region in which the combustion gas can be brought into contact with the coupling member is disposed in a region of the holding wall portion from the ejection port to the top wall portion, and

the actuator is configured in such a way that the coupling member is severed by the combustion gas being brought into contact with the coupling member in the contact region, whereby a state of the coupling member being held in the holder portion can be terminated.

2. The airbag device according to claim 1 , wherein

the holding wall portion is formed in an approximately tubular form centered on the direction of ejection of the combustion gas, and is of a configuration wherein a gas outflow hole that can cause the combustion gas to flow out toward the coupling member disposed in such a way as to cover the outer peripheral side is disposed penetrating, and

the gas outflow hole configures the contact region.

3. The airbag device according to claim 2 , wherein

the gas outflow hole is formed in a region wherein both edges of the gas outflow hole on a circumferential direction side are brought into contact with the coupling member in a cross-section of a side perpendicular to an axis of the holding wall portion when mounted in a vehicle.

4. The airbag device according to claim 1 , wherein

the holding wall portion is formed in an approximately tubular form centered on the direction of ejection of the combustion gas, and has an insertion hole through which the coupling member can be inserted, and an inner peripheral side is configured as the contact region.

5. The airbag device according to claim 1 , wherein

a cover wall covering sides of the actuator is disposed in positions on an outer side of the housing region in a periphery of the actuator in such a way as to extend from the housing region side.