Airbag apparatus

1. An airbag apparatus comprising:

an airbag housing installed on a seatback of a seat configured to support an occupant's upper body; and

an airbag accommodated in the airbag housing, and configured to be deployed to an outside of the airbag housing while being inflated when gas flows into the airbag,

wherein:

the airbag is configured to be deployed from an upper side of the occupant's head to a lower side of the occupant's head, and surrounds the occupant's upper body, together with the seatback;

the airbag comprises:

a rollover portion that protects an upper side and a front side of the occupant; and

side portions that are coupled to both lateral sides of the rollover portion, and protect both lateral sides of the occupant;

the rollover portion comprises an expandable portion that is configured to expand when gas flows into the expandable portion, and a non-expandable portion; and

the expandable portion comprises:

a first expandable portion disposed at a first side of the non-expandable portion;

a second expandable portion disposed at a second side of the non-expandable portion opposite the first side;

a third expandable portion which allows one end of the first expandable portion, one end of the second expandable portion, and the side portions to be in communication with one another;

a fourth expandable portion which allows the other end of the first expandable portion and the other end of the second expandable portion to be in communication with each other; and

a fifth expandable portion disposed between the third expandable portion and the fourth expandable portion, and allows the first expandable portion and the second expandable portion to be in communication with each other.

2. The airbag apparatus of claim 1 , wherein the airbag housing is installed on one of a back support portion of the seatback which supports the occupant's back, and a head support portion of the seatback which supports the occupant's head.

3. The airbag apparatus of claim 1 , wherein an inflator, which generates gas, is coupled to the rollover portion, and the side portions are in communication with the rollover portion and configured to be supplied with gas from the rollover portion.

4. The airbag apparatus of claim 1 , wherein the non-expandable portion is disposed inside the expandable portion.

5. The airbag apparatus of claim 1 , wherein the third expandable portion is configured to expand first by being supplied with gas from the inflator, and the fifth expandable portion and the fourth expandable portion are configured to expand while the first expandable portion, the second expandable portion, and the side portions expand from the rear side to the front side by gas flowing from the third expandable portion, such that the airbag is configured to be deployed from the upper side of the occupant's head to the lower side of the occupant's head while being deployed from the rear side to the front side.

6. The airbag apparatus of claim 1 , wherein when the airbag is deployed, the fourth expandable portion is disposed below the side portion.

7. The airbag apparatus of claim 1 , wherein when the airbag is deployed, the fourth expandable portion corresponds to a position of the occupant's chest, and the fifth expandable portion corresponds to a position of the occupant's head.

8. The airbag apparatus of claim 1 , further comprising a plurality of fifth expandable portions.

9. The airbag apparatus of claim 1 , wherein the side portion comprises:

an expandable portion configured to expand when gas flows into the expandable portion from the rollover portion; and

a non-expandable portion.

10. The airbag apparatus of claim 9 , wherein the non-expandable portion comprises:

a first non-expandable portion disposed inside the expandable portion; and

a second non-expandable portion which is coupled to the rollover portion.

11. An airbag apparatus comprising:

an airbag housing installed on a seatback of a seat configured to support an occupant's upper body; and

an airbag accommodated in the airbag housing, and configured to be deployed to an outside of the airbag housing while being inflated when gas flows into the airbag,

wherein:

the airbag is configured to be deployed from an upper side of the occupant's head to a lower side of the occupant's head, and surrounds the occupant's upper body, together with the seatback:

the airbag comprises:

a rollover portion that protects an upper side and a front side of the occupant; and

side portions that are coupled to both lateral sides of the rollover portion, and protect both lateral sides of the occupant;

the rollover portion comprises an expandable portion that is configured to expand when gas flows into the expandable portion, and a non-expandable portion; and

the expandable portion comprises:

a first expandable portion disposed at a first side of the non-expandable portion;

a second expandable portion which is disposed at a second side of the non-expandable portion opposite the first side;

a third expandable portion which allows one end of the first expandable portion, one end of the second expandable portion, and the side portions to be in communication with one another;

a fourth expandable portion which allows the other end of the first expandable portion and the other end of the second expandable portion to be in communication with each other; and

a fifth expandable portion disposed between the first expandable portion and the second expandable portion, and allows the third expandable portion and the fourth expandable portion to be in communication with each other.

12. The airbag apparatus of claim 11 , wherein when the airbag is deployed, the fourth expandable portion corresponds to a position of the occupant's chest, and the fifth expandable portion corresponds to a position of the occupant's head.

13. The airbag apparatus of claim 11 , further comprising a plurality of fifth expandable portions.