Airbag and airbag device

1. An airbag for protecting an occupant comprising:

a panel forming the airbag and having an occupant counter surface with a head counter portion to face a head of the occupant when the airbag is inflated, a recess portion formed in the head counter portion when the airbag is inflated, a regulation member for regulating inflation of the head counter portion toward the occupant, said regulation member forming the recess portion by regulating inflation of the head counter portion toward the occupant upon inflation of the airbag, and

a sub-regulation member for connecting a lower portion of the occupant counter surface which is located below the recess portion upon inflation of the airbag, and shorter in length than the regulation member,

wherein the regulation member and the sub-regulation member are formed of tether,

the regulation member includes a structure to release regulation after a predetermined time from a moment when the airbag starts inflation, and

the sub-regulation member ruptures before releasing the regulation of the regulation member upon inflation of the airbag, and the head counter portion of the airbag inflates earlier than the lower portion.

2. The airbag according to claim 1 , wherein the predetermined time is in a range from 15 to 40 msec from the moment when the airbag starts inflation.

3. The airbag according to claim 1 , wherein:

the regulation member is disposed inside the panel of the airbag, and connects the head counter portion to a side of the panel opposite the occupant; and

the regulation member is configured to rupture by a tensile force applied to the regulation member after the predetermined time from the moment when the airbag starts inflation to release connection between the head counter portion and the side opposite the occupant.

4. The airbag according to claim 3 , wherein the regulation member includes a fragile portion so as to be ruptured upon application of the tensile force to the regulation member, and the fragile portion is spaced from an end of the regulation member at a side opposite the occupant by 210 to 240 mm upon the inflation of the airbag.

5. The airbag according to claim 4 , wherein the regulation member includes an opening, and a circumferential edge of the opening serves as the fragile portion.

6. The airbag according to claim 4 , wherein the regulation member is formed of a woven cloth having a weaving structure obliquely crossing with respect to a tensile direction at least in the fragile portion of the regulation member.

7. The airbag according to claim 6 , wherein said end of the regulation member and a surrounding portion of the regulation member have a weaving direction of the woven cloth substantially parallel with the tensile direction.

8. The airbag according to claim 1 , wherein the sub-regulation member is configured to be ruptured after an elapse of 10 to 30 msec from the moment when the airbag starts inflating.

9. The airbag according to claim 1 , wherein:

the sub-regulation member includes a fragile portion ruptured by tensile force applied to the sub-regulation member before releasing regulation of the regulation member from the moment when the airbag starts inflating; and

the fragile portion of the sub-regulation member is spaced from an end of the sub-regulation member at the side opposite the occupant upon inflation of the airbag in a range from 190 to 220 mm.

10. The airbag according to claim 9 , wherein the sub-regulation member includes an opening, and a circumferential edge portion of the opening is formed as the fragile portion.

11. The airbag according to claim 9 , wherein the sub-regulation member is formed of a woven cloth having a weaving structure obliquely crossing with respect to a tensile direction at least in the fragile portion of the sub-regulation member.

12. The airbag according to claim 11 , wherein the sub-regulation member includes an end and a surrounding area thereof at the side opposite the occupant upon inflation of the airbag, the end and the surrounding area having at least a weaving direction of the woven cloth substantially parallel with the tensile direction.

13. An airbag device comprising the airbag according to claim 1 , and an inflator for inflating the airbag.

14. An airbag according to claim 1 , wherein the regulation member is connected to a front end portion opposite to the occupant counter face of the airbag and having a folded back portion folding back a front end of the regulation member by a predetermined length, to a lower surface of the front end portion when the airbag is folded, a fold line of the folded back portion facing a front of a vehicle.

15. An airbag according to claim 1 , wherein the regulation member includes a first half panel having one end joined with the recess portion of the occupant counter surface and a second half panel having one end joined with a front end portion opposite to the occupant counter surface of the airbag, the other ends of the first half panel and the second half panel are joined together, and the second half panel has a higher rupture strength than the first half panel.

16. An airbag according to claim 1 , wherein the sub-regulation member includes a first half panel having one end joined with the lower portion of the occupant counter surface, and a second half panel having one end joined with a front end portion opposite to the occupant counter surface of the airbag, the other ends of the first half panel and the second half panel are joined together, and the second half panel has a higher rupture strength than the first half panel.

17. An airbag according to claim 1 , further comprising a front end portion opposite to the occupant counter surface; and a reinforcing cloth attached to a surface of the panel at the front end of portion of the airbag.