Airbag, airbag device and vehicle

1. An airbag for protecting an occupant, comprising:

a left half airbag to be inflated at a front left of the occupant and having a distal end and a vertically curved surface projecting toward the occupant in a middle portion thereof when inflated, and

a right half airbag to be inflated at a front right of the occupant and having a distal end and a vertically curved surface projecting toward the occupant in a middle portion thereof when inflated, said distal ends of the left and right half airbags being unconnected and separated from each other to form a space therebetween facing the occupant when the airbag is inflated.

2. An airbag according to claim 1 , wherein said distal ends of the left and right half airbags are spaced apart from each other by a distance between 150 and 450 mm, and are located away from a deepest bottom of the space by 280 to 480 mm in a horizontal direction when the airbag is inflated.

3. An airbag according to claim 1 , further comprising a base for communicating the left and right half airbags, said left and right half airbags being inflatable by a common inflator.

4. An airbag according to claim 1 , wherein said left half airbag is connected with the right half airbag at midsections thereof so that the distal ends of the left and right half airbags are located away from the midsections by 50 to 300 mm in a horizontal direction when the airbag is inflated.

5. An airbag according to claim 4 , wherein each of said left half airbag and said right half airbag is formed of a plurality of panels having joint allowances disposed at the midsection, said left half airbag being connected with the right half airbag at the joint allowances.

6. An airbag according to claim 1 , wherein at least one of said left half airbag and said right half airbag has an inclined upper portion when the airbag is inflated.

7. An airbag according to claim 1 , wherein at least one of said left half airbag and said right half airbag has a width gradually decreasing upwardly when the airbag is inflated.

8. An airbag for protecting an occupant, comprising:

a left half airbag to be inflated at a front left of the occupant and having a distal end and a vertically curved surface projecting toward the occupant in a middle portion thereof when inflated, and

a right half airbag to be inflated at a front right of the occupant and having a distal end and a vertically curved surface projecting toward the occupant in a middle portion thereof when inflated, said distal ends of the left and right half airbags being unconnected and separated from each other to form a space therebetween facing the occupant when the airbag is inflated,

wherein each of said left and right half airbags has a vent hole formed at a side surface thereof at a position around a center of the side surface or upper front of the center.

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

10. An airbag device according to claim 9 , wherein said airbag is inflated at a gas pressure less than 440 kPa.

11. A vehicle provided with the airbag device according to claim 9 .

12. A vehicle provided with an airbag device comprising an airbag and an inflator for inflating the airbag, said airbag comprising:

a left half airbag to be inflated at a front left of the occupant and having a distal end and a vertically curved surface projecting toward the occupant in a middle portion thereof when inflated , and

a right half airbag to be inflated at a front right of the occupant and having a distal end and a vertically curved surface projecting toward the occupant in a middle portion thereof when inflated, said distal ends of the left and right half airbags being unconnected and separated from each other to form a space therebetween facing the occupant when the airbag is inflated,

wherein said airbag device is installed in an instrumental panel of the vehicle, and said airbag is a passenger airbag having vent holes in side surfaces thereof facing outwardly so that a ratio L 2 /L 1 of a horizontal distance L 1 between a rear edge of the instrumental panel and the distal ends of the left and right half airbags to a horizontal distance L 2 between the rear edge of the instrumental panel and the vent holes is between 0.25 to 0.50.

13. A vehicle provided with an airbag device comprising an airbag and an inflator for inflating the airbag, said airbag comprising:

a left half airbag to be inflated at a front left of the occupant and having a distal end and a vertically curved surface projecting toward the occupant in a middle portion thereof when inflated, and

a right half airbag to be inflated at a front right of the occupant and having a distal end and a vertically curved surface projecting toward the occupant in a middle portion thereof when inflated, said distal ends of the left and right half airbags being unconnected and separated from each other to form a space therebetween facing the occupant when the airbag is inflated,

wherein said airbag device is installed in an instrumental panel of the vehicle, and said airbag is a passenger airbag having vent holes in side surfaces thereof facing outwardly so that a ratio H 2 /H 1 of a vertical distance H 1 between an upper edge of the instrumental panel and an upper end of the airbag to a vertical distance between the upper edge of the instrumental panel and the vent holes is between 0.3 to 0.50.

14. A vehicle according to claim 11 , further comprising at least one of a curtain airbag device, a knee airbag device, a knee protector, a side airbag device and a seat cushion bag device.

15. An airbag according to claim 1 , wherein each of said vertically curved surfaces of said left and right half airbags has upper and lower portions with respect to the middle portion, respectively, and projects from the upper and lower portions to the middle portion close to a body of the occupant.