Method of folding passenger-seat airbag

1. A method of folding a passenger-seat airbag that includes an airbag body including a left airbag and a right airbag that correspond to left and right shoulders of an occupant seated at a passenger seat; and a root portion that receives gas injected from an inflator when the inflator operates, and that connects a left-airbag root portion and a right-airbag root portion, the method comprising:

folding each of the left and right airbags in a left-and-right direction when the passenger-seat airbag is provided in the vehicle, such that each of the left and right airbags has a strip shape, and then folding the left and right airbags that are overlapped with each other, toward one side in a longitudinal direction to form an airbag folded portion, wherein the left and right airbags are positioned closer to a rear of a vehicle than the root portion is when the passenger-seat airbag is provided in the vehicle; and

making the root portion slack to form a slack portion, and making the slack portion upright along the airbag folded portion after the slack portion is extended toward a front of the vehicle, wherein the root portion is positioned closer to the front of the vehicle than the left and right airbags are when the passenger-seat airbag is provided in the vehicle, wherein a tip portion of the slack portion is accordion-folded only once so that the tip portion terminates in a downward direction, perpendicular to a bottom of an airbag case; and

wherein when the gas is supplied to the root portion, the slack portion starts to expand and deploy before the airbag folded portion starts to expand and deploy; and the root portion is expanded toward a windshield so that the slack portion is a first portion of the passenger-seat airbag to contact the windshield thereby forming a wall in an airbag deployment area at a position close to the front of the vehicle so that the airbag folded portion receives a reaction force from the wall.

2. The method according to claim 1 , wherein surfaces of each of the left and right airbags, which are left and right surfaces of each of the left and right airbags when each of the left and right airbags is deployed in the vehicle, are overlapped with each other so that each of the left and right airbags is flat; a lower portion of each of the left and right airbags, which is a lower one-third portion in a vehicle-height direction when each of the left and right airbags is deployed in the vehicle, is accordion-folded toward a center of each of the left and right airbags; an upper portion of each of the left and right airbags, which is an upper one-third portion in the vehicle-height direction when each of the left and right airbags is deployed in the vehicle, is rolled up toward the center; and the rolled-up upper portion is placed on the accordion-folded lower portion so that each of the left and right airbags has the strip shape.

3. The method according to claim 1 , wherein the airbag folded portion is formed mainly by rolling up the airbag body.

4. The method according to claim 1 , wherein the airbag folded portion is formed by rolling up an end portion of the airbag body, which is distant from the root portion, twice to form a rolled-up portion, and then accordion-folding another end portion of the airbag body, which is close to the root portion, once to form an accordion-folded portion, and placing the rolled-up portion on the accordion-folded portion.

5. The method according to claim 1 , wherein the airbag folded portion is formed by rolling up an end portion of the airbag body, which is distant from the root portion, once to form a rolled-up portion, and then accordion-folding another end portion of the airbag body, which is close to the root portion, once to form an accordion-folded portion, and placing the accordion-folded portion on the rolled-up portion.

6. The method according to claim 1 , wherein the airbag folded portion is formed by rolling up the airbag body three times.

7. The method according to claim 1 , wherein the airbag folded portion is formed by accordion-folding the airbag body twice.

8. The method according to claim 1 , wherein the tip portion of the slack portion that forms the root portion is accordion-folded toward the airbag folded portion.

9. A passenger-seat airbag device, comprising:

the passenger-seat airbag that is folded by the method according to claim 1 ;

the inflator that injects the gas; and

an airbag case in which the passenger-seat airbag and the inflator are housed.

10. The passenger-seat airbag device according to claim 9 ,

wherein the airbag body includes a left airbag and a right airbag; and

wherein when the passenger-seat airbag is inflated, a substantially center of an inner portion of the left airbag contacts a substantially center of an inner portion of the right airbag.

11. The passenger-seat airbag device according to claim 9 ,

wherein the airbag body includes a left airbag and a right airbag; and

wherein the passenger-seat airbag device further comprises a connection member that connects a rear end of the left airbag with a rear end of the right airbag.

12. A method of folding a passenger-seat airbag that includes an airbag body including a left airbag and a right airbag that correspond to left and right shoulders of an occupant seated in a passenger seat; and a root portion that receives gas injected from an inflator when the inflator operates, and that connects a left-airbag root portion and a right-airbag root portion, the method comprising:

folding each of the left and right airbags in a left-and-right direction when the passenger-seat airbag is provided in the vehicle, such that each of the left and right airbags has a strip shape, and then folding the left and right airbags that are overlapped with each other, toward one side in a longitudinal direction into an airbag case having a front wall proximate to a front of the vehicle to form an airbag folded portion, wherein the left and right airbags are positioned closer to a rear of a vehicle than the root portion is when the passenger-seat airbag is provided in the vehicle; and

making the root portion slack to form a slack portion, and making the slack portion upright along the airbag folded portion after the slack portion is extended toward a front of the vehicle, wherein the root portion is positioned closer to the front of the vehicle than the left and right airbags are when the passenger-seat airbag is provided in the vehicle;

wherein the slack portion includes a tip portion located between the airbag folded portion and a remainder of the slack portion, with the remainder of the slack portion located between the tip portion and the front wall, the tip portion of the slack portion accordion-folded only once; and

wherein when the gas is supplied to the root portion, the slack portion starts to expand and deploy before the airbag folded portion starts to expand and deploy; and the root portion is expanded toward a windshield so that the slack portion is a first portion of the passenger-seat airbag to contact the windshield thereby forming a wall in an airbag deployment area at a position close to the front of the vehicle so that the airbag folded portion receives a reaction force from the wall.

13. A method of folding a passenger-seat airbag that includes an airbag body including a left airbag and a right airbag that correspond to left and right shoulders of an occupant seated at a passenger seat; and a root portion that receives gas injected from an inflator when the inflator operates, and that connects a left-airbag root portion and a right-airbag root portion, the method comprising:

folding each of the left and right airbags in a left-and-right direction when the passenger-seat airbag is provided in the vehicle, such that each of the left and right airbags has a strip shape, and then folding the left and right airbags that are overlapped with each other, toward one side in a longitudinal direction to form an airbag folded portion, wherein the left and right airbags are positioned closer to a rear of a vehicle than the root portion is when the passenger-seat airbag is provided in the vehicle; and

making the root portion slack to form a slack portion, and making the slack portion upright along the airbag folded portion after the slack portion is extended toward a front of the vehicle, wherein the root portion is positioned closer to the front of the vehicle than the left and right airbags are when the passenger-seat airbag is provided in the vehicle, and wherein a tip portion of the slack portion that forms the root portion is bent toward the airbag folded portion at a substantially right angle; and

wherein when the gas is supplied to the root portion, the slack portion starts to expand and deploy before the airbag folded portion starts to expand and deploy; and the root portion is expanded toward a windshield so that the slack portion is a first portion of the passenger-seat airbag to contact the windshield thereby forming a wall in an airbag deployment area at a position close to the front of the vehicle so that the airbag folded portion receives a reaction force from the wall.

14. The method according to claim 13 , wherein the tip portion of the slack portion is positioned above the airbag folded portion.

15. A method of folding a passenger-seat airbag that includes an airbag body including a left airbag and a right airbag that correspond to left and right shoulders of an occupant seated at a passenger seat; and a root portion that receives gas injected from an inflator when the inflator operates, and that connects a left-airbag root portion and a right-airbag root portion, the method comprising:

folding each of the left and right airbags in a left-and-right direction when the passenger-seat airbag is provided in the vehicle, such that each of the left and right airbags has a strip shape, and then folding the left and right airbags that are overlapped with each other, toward one side in a longitudinal direction to form an airbag folded portion, wherein the left and right airbags are positioned closer to a rear of a vehicle than the root portion is when the passenger-seat airbag is provided in the vehicle; and

making the root portion slack to form a slack portion, and making the slack portion upright along the airbag folded portion after the slack portion is extended toward a front of the vehicle, wherein the root portion is positioned closer to the front of the vehicle than the left and right airbags are when the passenger-seat airbag is provided in the vehicle, and wherein a tip portion of the slack portion that forms the root portion is oriented toward a top of the vehicle such that the tip portion is in a substantially upright state; and

wherein when the gas is supplied to the root portion, the slack portion starts to expand and deploy before the airbag folded portion starts to expand and deploy; and the root portion is expanded toward a windshield so that the slack portion is a first portion of the passenger-seat airbag to contact the windshield thereby forming a wall in an airbag deployment area at a position close to the front of the vehicle so that the airbag folded portion receives a reaction force from the wall.