Side airbag apparatus

1. A side airbag apparatus applied to a vehicle, the vehicle being structured such that a seat back of a vehicular seat is provided with a seat frame and a seat pad arranged near the seat frame, wherein a rear frame portion of the seat frame is arranged near a rear end in an intermediate portion in a vehicle width direction of the seat back, and an intermediate pad portion of the seat pad is arranged near a front end in the intermediate portion, the side airbag apparatus comprising:

an inflator; and

an airbag inflated by a gas jetted out of the inflator,

wherein the inflator and the airbag are incorporated at least on an outer side portion of the seat back,

wherein the airbag has a main airbag and an auxiliary airbag,

wherein the main airbag is inflated between a body side portion of the vehicle and an occupant seated on the vehicular seat by being caused to shoot out forward from an outer side portion of the seat back by a gas from the inflator, and

wherein the auxiliary airbag pressing a portion near the outer side portion of the intermediate pad portion forward by being inflated between the rear frame portion and the intermediate pad portion by the gas from the inflator.

2. The side airbag apparatus according to claim 1 , wherein the auxiliary airbag is supplied with the gas from the inflator prior to the main airbag.

3. The side airbag apparatus according to claim 2 , wherein the main airbag and the auxiliary airbag are coupled to each other via a communicating hole portion connecting the interior of the main airbag and the interior of the auxiliary airbag to each other, and

wherein the inflator is arranged within the auxiliary airbag.

4. The side airbag apparatus according to claim 3 , wherein the inflator is formed as an elongated shape,

wherein a gas outlet port is provided in one end portion of the inflator, and

wherein the communicating hole portion is located close to an end portion on an opposite side to the gas outlet port of the inflator.

5. The side airbag apparatus according to claim 3 , wherein an outer side frame portion constructing the seat frame is arranged within an outer side portion of the seat back,

wherein an inner side frame portion constructing the seat frame is arranged within an inner side portion of the seat back, and

wherein the auxiliary airbag is arranged on the vehicle inner side of the outer side frame portion in a state of being folded independently from the main airbag.

6. The side airbag apparatus according to claim 5 , further comprising guide means for guiding the auxiliary airbag between the rear frame portion and the intermediate pad portion at least in an early stage of the inflation of the auxiliary airbag.

7. The side airbag apparatus according to claim 6 , wherein the guide means is provided with a rear guide member arranged on the front side of the rear frame portion, and the rear guide member has a rear guide surface which is substantially orthogonal to a forward moving direction of the vehicle.

8. The side airbag apparatus according to claim 6 , wherein the guide means is constituted by a band-like member extending along a vehicle width direction, and

wherein a part of the band-like member is put through a gap provided at a position other than the communicating hole portion between the main airbag and the auxiliary airbag.

9. The side airbag apparatus according to claim 8 , wherein a band body that is made of a material having a low extendability and provided for assisting a breakage of the outer side portion by the inflating main airbag is arranged around an outer side portion of the seat pad, and

wherein the band body is used as the band-like member, and a part of the band body is put through the gap.

10. The side airbag apparatus according to claim 8 , wherein one end portion of the band-like member is fixed to the outer side frame portion, and

wherein the other end portion of the band-like member is fixed to the inner side frame portion.

11. The side airbag apparatus according to claim 1 , wherein the auxiliary airbag is arranged in a state of being deployed between the rear frame portion and the intermediate pad portion,

wherein a band-like member for retaining the auxiliary airbag in a deployed state is provided within the seat back,

wherein one end portion of the band-like member is coupled to an inner end of the auxiliary airbag, and

wherein the other end portion of the band-like member is coupled to the vehicle inner side than the inner end of the auxiliary airbag in the seat frame.

12. The side airbag apparatus according to claim 2 , wherein the main airbag and the auxiliary airbag are arranged in an independent state from each other,

wherein the inflator comprises:

a main inflator arranged within the main airbag; and

an auxiliary inflator arranged within the auxiliary airbag, and

wherein the auxiliary inflator starts supplying the gas to the auxiliary airbag prior to the main inflator.

13. The side airbag apparatus according to claim 1 , wherein a pressure receiving plate receiving a pressure of the gas within the auxiliary airbag so as to generate a forward reaction force is arranged on the rear side of the rear frame portion.