Patent Publication Number: US-2023143871-A1

Title: Airbag device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of priority of Japanese Patent Application No. 2021-182569, filed on Nov. 9, 2021, the content of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to an airbag device that protects an occupant seated on a vehicle seat of a vehicle from an impact when the impact is applied to the vehicle from an obliquely front outer side of the vehicle seat. 
     BACKGROUND ART 
     When an impact is applied to a wheeled vehicle from an obliquely front outer side of a wheeled-vehicle seat due to an oblique collision or the like, an upper body of an occupant seated on the wheeled-vehicle seat tends to move toward the obliquely front outer side, which is the side to which the impact is applied, due to inertia. 
     In this case, an airbag device is effective in which, when an impact is applied to the wheeled vehicle from the obliquely front outer side of the wheeled-vehicle seat, or when it is predicted that an impact is to be applied to the wheeled vehicle, an airbag is deployed and inflated by an inflation gas to protect the occupant seated on the wheeled-vehicle seat from the impact. 
     For example, an airbag of an airbag device disclosed in JP2006-8105A includes a main inflation portion (airbag main body portion) and an auxiliary inflation portion (airbag protruding portion). Here, in a width direction of a seatback of a wheeled-vehicle seat, a side closer to a central portion of the seatback in the width direction is defined as an inner side, and a side farther from the central portion is defined as an outer side. The main inflation portion is deployed and inflated forward at an outer side of an upper body of an occupant. A front end portion of the main inflation portion is positioned at an obliquely front outer side with respect to a head portion of the occupant. 
     The auxiliary inflation portion includes an annular side portion constituting an outer peripheral portion of the auxiliary inflation portion, a front main body portion surrounded by a front edge portion of the annular side portion, and a rear main body portion surrounded by a rear edge portion of the annular side portion. The auxiliary inflation portion is joined to the front end portion of the main inflation portion at the annular side portion, in a state of being in communication with the main inflation portion. An inflation gas is supplied from the main inflation portion to the auxiliary inflation portion through the communication portion. The auxiliary inflation portion is deployed and inflated toward the inner side from the front end portion of the main inflation portion, more specifically, toward a position forward of the head portion of the occupant. 
     Therefore, the upper body of the occupant that tends to move toward the obliquely front outer side as described above can be caught by the main inflation portion and the auxiliary inflation portion, and the upper body can be protected from an impact. 
     The parenthesized words following the member names indicate member names used in JP2006-8105A. 
     SUMMARY OF INVENTION 
     In recent years, there has been a demand to prevent phenomena. The phenomena include one in which an upper body of an occupant moves when an impact is applied to a wheeled vehicle from an obliquely front outer side of a wheeled-vehicle seat, and one in which a head portion of the occupant rotates about an axis of a neck portion when the impact is applied. 
     However, the airbag device disclosed in JP2006-8105A is designed mainly for preventing the phenomenon in which the upper body of an occupant moves, and prevention of rotation of the head portion is not considered. 
     Therefore, when the head portion comes into contact with the auxiliary inflation portion, the auxiliary inflation portion may rotate toward an outer side in a front direction about a joint portion with the main inflation portion. Therefore, with respect to the airbag device disclosed in JP2006-8105A, there is room for improvement in terms of preventing the rotation of the head portion about the axis of the neck portion. 
     Solution to Problem 
     To solve the above problem, there is provided an airbag device for protecting an occupant seated on a vehicle seat of a vehicle from an impact by deploying and inflating an airbag with an inflation gas in a case where the impact is applied to the vehicle from an obliquely front outer side of the vehicle seat or in a case where it is predicted that the impact is to be applied to the vehicle. When in a width direction of a seatback of the vehicle seat, a side closer to a central portion of the seatback in the width direction is defined as an inner side and a side farther from the central portion of the seatback in the width direction is defined as an outer side, the airbag includes a main inflation portion that is to be deployed and inflated at the outer side of an upper body of the occupant, and an auxiliary inflation portion that is disposed at a position adjacent to the inner side of the main inflation portion and that is to be deployed and inflated at an obliquely front outer side of a head portion of the occupant by the inflation gas passing through the main inflation portion. The auxiliary inflation portion is joined to the main inflation portion in a joining area, in a state of being in communication with the main inflation portion. The auxiliary inflation portion includes an annular side portion constituting an outer peripheral portion, an outer main body portion surrounded by an outer edge portion of the annular side portion, and an inner main body portion surrounded by an inner edge portion of the annular side portion. In the auxiliary inflation portion whose deployment and inflation are completed, a maximum dimension in a facing direction in which the outer main body portion and the inner main body portion face each other is set to be smaller than a dimension in a direction orthogonal to the facing direction. The outer main body portion is joined to the main inflation portion as the joining area of the auxiliary inflation portion. 
     According to the above configuration, when the impact is applied to the vehicle from the obliquely front outer side of the vehicle seat, the upper body including the head portion of the occupant seated on the vehicle seat tends to move toward the obliquely front outer side, which is the side to which the impact is applied, due to inertia. At this time, the head portion of the occupant tends to rotate about an axis of a neck portion of the occupant. 
     On the other hand, in the airbag device, the inflation gas is supplied to the airbag in a case where the impact is applied to the vehicle from the obliquely front outer side of the vehicle seat, or in a case where it is predicted that the impact is to be applied to the vehicle. A part of the inflation gas supplied to the main inflation portion flows into the auxiliary inflation portion communicating with the main inflation portion, through the communication portion. With the inflation gas, the main inflation portion and the auxiliary inflation portion are deployed and inflated. 
     Here, the main inflation portion is deployed and inflated at an outer side of the upper body of the occupant. Therefore, the upper body of the occupant is caught by the main inflation portion, and the upper body is prevented from moving toward the obliquely front outer side, so that the upper body is protected from the impact. 
     The auxiliary inflation portion is deployed and inflated at a position adjacent to the inner side of the main inflation portion, which is an obliquely front outer side of the head portion of the occupant. Therefore, even if the head portion of the occupant is about to rotate about the axis of the neck portion, the rotation is prevented by contact with the auxiliary inflation portion and the main inflation portion. 
     In particular, the auxiliary inflation portion has the outer main body portion as the joining area, and is joined to the main inflation portion in the joining area. Here, in the auxiliary inflation portion whose deployment and inflation are completed, the maximum dimension of the outer main body portion and the inner main body portion in the facing direction is smaller than the dimension of the outer main body portion and the inner main body portion in the direction orthogonal to the facing direction. Therefore, as described above, when the outer main body portion is set as the joining area, the joining area can be wider than when the annular side portion is set as the joining area. When the auxiliary inflation portion is joined to the main inflation portion in the wide joining area, a posture of the auxiliary inflation portion with respect to the main inflation portion is stabilized. A phenomenon in which the auxiliary inflation portion rotates toward a front outer side about a joint portion with the main inflation portion due to contact with the head portion is prevented. A phenomenon in which the performance of preventing the rotation of the head portion about the axis of the neck portion is lowered due to the rotation of the auxiliary inflation portion is prevented. 
     In the airbag device described above, it is preferable that, when deployment and inflation of the main inflation portion and the auxiliary inflation portion are completed, both the main inflation portion and the auxiliary inflation portion are inclined with respect to a front-rear direction such that a front side of the main inflation portion and a front side of the auxiliary inflation portion are positioned at a front outer side. 
     According to the above configuration, the auxiliary inflation portion is deployed and inflated at a front side in a movement direction of the head portion. In addition, the main inflation portion and the auxiliary inflation portion, whose deployment and inflation are completed, are inclined with respect to the front-rear direction such that the front side of the main inflation portion and the front side of the auxiliary inflation portion are positioned at the front outer side. Due to this inclination, a boundary portion between the main inflation portion and the auxiliary inflation portion is positioned at the front side in the movement direction of the head portion. 
     Therefore, the head portion is caught by both the main inflation portion and the auxiliary inflation portion, and the rotation of the head portion about the neck portion can be further prevented. 
     In the airbag device described above, an auxiliary communication hole, with which an inside and an outside of the auxiliary inflation portion communicate with each other, is preferably formed in the outer main body portion, a main communication hole, with which an inside and an outside of the main inflation portion communicate with each other, is preferably formed in a portion of the main inflation portion adjacent to the auxiliary communication hole, and a peripheral portion of the main communication hole in the main inflation portion and a peripheral portion of the auxiliary communication hole in the outer main body portion are preferably overlapped with each other and joined to each other by an annular joint portion. 
     According to the above configuration, the peripheral portion of the main communication hole in the main inflation portion and the peripheral portion of the auxiliary communication hole in the outer main body portion are joined by the annular joint portion, whereby the auxiliary inflation portion is joined to the main inflation portion in the joining area. 
     The main inflation portion and the auxiliary inflation portion communicate with each other via the main communication hole and the auxiliary communication hole. Therefore, a part of the inflation gas supplied to the main inflation portion flows into the auxiliary inflation portion through the main communication hole and the auxiliary communication hole. 
     In the airbag device described above, it is preferable that a combination of the main communication hole, the auxiliary communication hole, and the annular joint portion is provided at a plurality of positions in the joining area. 
     According to the above configuration, the combination of the main communication hole, the auxiliary communication hole, and the annular joint portion is provided at a plurality of positions in the joining area, so that the auxiliary inflation portion is joined to the main inflation portion at a plurality of positions in the joining area. 
     The main inflation portion and the auxiliary inflation portion communicate with each other via the main communication hole and the auxiliary communication hole of each of the combinations provided at a plurality of positions in the joining area. Therefore, a part of the inflation gas supplied to the main inflation portion flows into the auxiliary inflation portion through the main communication hole and the auxiliary communication hole of each combination. 
     In the airbag device described above, when a distance between a front end portion of the annular joint portion positioned at a foremost position and a rear end portion of the annular joint portion positioned at a rearmost position in the joining area is defined as a front-rear length of the joining area, the maximum dimension in the facing direction is preferably set to be smaller than the front-rear length of the joining area. 
     According to the above configuration, the front-rear length of the joining area, which is a region where the auxiliary inflation portion is actually joined to the main inflation portion, is compared with the maximum dimension of the auxiliary inflation portion in the facing direction. The maximum dimension is set to be smaller than the front-rear length. 
     Therefore, the auxiliary inflation portion is joined to the main inflation portion in a wider joining area than in a case where the annular side portion is set as the joining area, and the posture of the auxiliary inflation portion with respect to the main inflation portion is stabilized. Accordingly, a phenomenon in which the auxiliary inflation portion rotates about the joint portion with the main inflation portion due to contact with the head portion is prevented. 
     According to the airbag device described above, when an impact is applied to a vehicle from an obliquely front outer side of a vehicle seat, a head portion of an occupant can be prevented from rotating about an axis of a neck portion. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a partial plan view of a wheeled vehicle to which a far-side airbag device is applied in an embodiment. 
         FIG.  2    is a partial cross-sectional plan view illustrating an internal structure of a side portion of a seatback in which an airbag module is stored in the embodiment. 
         FIG.  3    is a partial perspective view illustrating an airbag, of which both a main inflation portion and an auxiliary inflation portion are deployed and inflated, together with an occupant and a wheeled-vehicle seat in the embodiment. 
         FIG.  4    is a partial plan view illustrating a positional relationship between the wheeled-vehicle seat, the airbag, the occupant, and a side wall portion in the embodiment. 
         FIG.  5    is a partial plan view illustrating the deployed and inflated airbag together with a head portion of the occupant in the embodiment. 
         FIG.  6    is a partial cross-sectional plan view illustrating an internal structure of the deployed and inflated airbag together with the head portion of the occupant in the embodiment. 
         FIG.  7    is a partial side view illustrating a joint portion of an outer main body portion of the auxiliary inflation portion to the main inflation portion in the embodiment. 
         FIG.  8    is a view corresponding to  FIG.  6   , and is a partial cross-sectional plan view illustrating a deployed and inflated airbag of a modification together with the head portion of the occupant. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment in which an airbag device is embodied as a far-side airbag device for a wheeled vehicle will be described with reference to  FIGS.  1  to  7   . 
     In the following description, an advancing direction of a wheeled vehicle is defined as a front side, and a reversing direction is defined as a rear side. An up-down direction means an up-down direction of the wheeled vehicle. A left-right direction is a wheeled-vehicle width direction, and coincides with the left-right direction at the time of advancing of the wheeled vehicle. In addition, it is assumed that an occupant having the same physique as that of a crash test dummy sits on a wheeled-vehicle seat in a predetermined appropriate posture. 
     As illustrated in  FIG.  1   , two side portions of a wheeled vehicle  10  in the left-right direction are implemented by side wall portions  11  and  12  respectively, each including a door, a pillar, and the like. In a wheeled-vehicle interior, wheeled-vehicle seats  13  and  14  as front seats are arranged side by side in the left-right direction. The wheeled-vehicle seat  13  close to the side wall portion  11  functions as a driver’s seat, and an occupant (driver) P 1  is seated on the wheeled-vehicle seat  13 . The wheeled-vehicle seat  14  close to the side wall portion  12  functions as a front passenger seat, and an occupant (front passenger seat occupant) P 2  is seated on the wheeled-vehicle seat  14 . The wheeled-vehicle seats  13  and  14  have the same configuration. Therefore, only the wheeled-vehicle seat  13  will be described here. 
     Schematic Configuration of Wheeled-Vehicle Seat  13   
     As illustrated in  FIGS.  2  and  4   , the wheeled-vehicle seat  13  includes a seat cushion  15 , a seatback  16 , and a headrest  20 . The seat cushion  15  is a portion on which the occupant P 1  is seated, and is configured to be slidable in a front-rear direction. The seatback  16  supports the upper body of the occupant P 1  from the rear side. The seatback  16  stands upright from a rear portion of the seat cushion  15 , and is configured such that an inclination angle thereof can be adjusted. The headrest  20  supports ahead portion PH of the occupant P 1  from the rear side, and is disposed on the seatback  16 . The wheeled-vehicle seat  13  is disposed in a posture in which the seatback  16  faces the front side. A width direction of the wheeled-vehicle seat  13  disposed in this manner coincides with the left-right direction. 
     Here, as illustrated in  FIG.  4   , in order to specify portions of the seatback  16  in the width direction, a central portion  16   c  of the seatback  16  in the width direction is used as a reference. In the width direction, a side closer to the central portion  16   c  is referred to as an “inner side”, and a side farther from the central portion  16   c  is referred to as an “outer side”. 
       FIG.  2    illustrates an internal structure of a side portion  17  of the seatback  16  of the wheeled-vehicle seat  13  on a side close to the wheeled-vehicle seat  14 . A seat frame that forms a framework portion of the seatback  16  is disposed inside the seatback  16 . 
     A side frame portion  18  constituting a part of the seat frame is disposed inside the side portion  17 . The side frame portion  18  is formed by subjecting a metal plate to bending or the like. 
     A seat pad  19  made of an elastic material such as urethane foam is disposed on the front side of the seat frame including the side frame portion  18 . A backboard  21  made of a synthetic resin or the like is disposed on the rear side of the seat frame. Although the seat pad  19  is covered with a skin, the skin is not illustrated in  FIG.  2   . 
     A storage portion  22  is provided inside the side portion  17 , at an outer side of the side frame portion  18 . The storage portion  22  is a space in which an airbag module ABM, which is a main portion of the far-side airbag device, is stored. 
     A slit  23  extends toward an obliquely front outer side from an outer corner portion of a front portion of the storage portion  22 . A portion sandwiched between a front corner portion 19c of the seat pad  19  and the slit  23  (that is, a portion surrounded by a frame of a two-dot chain line in  FIG.  2   ) constitutes a breakage-expected portion  24  to be broken by an airbag  31  to be described later. 
     The airbag module ABM includes, as main components, the airbag  31  and a gas generator  25  that supplies an inflation gas to the airbag  31 . Next, each of these components will be described. 
     Gas Generator  25   
     The gas generator  25  includes an inflator  26  and a retainer  27  that covers the inflator  26 . Here, a pyrotechnic type inflator is employed as the inflator  26 . The inflator  26  has a substantially columnar shape, and a gas generating agent (not illustrated) that generates an inflation gas is accommodated inside the inflator  26 . The inflator  26  includes a gas ejection portion  26   a  at an upper end portion thereof. A harness (not illustrated), which is an input wiring of an actuation signal to the inflator  26 , is connected to a lower end portion of the inflator  26 . 
     Instead of the pyrotechnic type inflator using a gas generating agent, the inflator  26  may be of a type that ejects an inflation gas by using an explosive or the like to break a partition wall of a high-pressure gas cylinder filled with a high-pressure gas. 
     On the other hand, the retainer  27  is a member that functions as a diffuser for controlling a direction in which the inflation gas is ejected, and that fastens the inflator  26 , the airbag  31  and the like to the side frame portion  18 . Most of the retainer  27  is formed in a substantially tubular shape by bending a plate material such as a metal plate. A bolt  28  extending toward the inner side is fixed to the retainer  27  as a member for attaching the retainer  27  to the side frame portion  18 . 
     In the gas generator  25 , the inflator  26  and the retainer  27  may be integrated. The gas generator  25  may only include the inflator  26 , with the retainer  27  not being used. In this case, the bolt  28  is fixed to the inflator  26 . 
     Airbag  31   
     As illustrated in  FIGS.  3  and  4   , the airbag  31  includes a main inflation portion  32  and an auxiliary inflation portion  41  having a smaller capacity than the main inflation portion  32 . Each of the main inflation portion  32  and the auxiliary inflation portion  41  is formed of a fabric piece (also referred to as a base fabric, a panel fabric, or the like). As the fabric piece, a material having a high strength and flexibility and capable of being easily folded is used, for example, a woven fabric formed of a polyester yarn, a polyamide yarn, or the like. 
     The main inflation portion  32  is formed by, for example, folding a fabric piece into two pieces and overlapping the two pieces in the left-right direction, and joining overlapping portions thereof by a main peripheral joint portion  33 . Here, in order to distinguish between the two overlapped portions of the main inflation portion  32 , the portion positioned on the outer side is referred to as a main fabric portion  34 , and the portion positioned on the inner side is referred to as a main fabric portion  35 . 
     The main inflation portion  32  may be implemented by two fabric pieces. In this case, the main inflation portion  32  is formed by overlapping the two fabric pieces in the left-right direction and joining the two fabric pieces over entire circumferences thereof by the main peripheral j oint portion  33 . 
     Although the main peripheral joint portion  33  is formed by sewing, the main peripheral joint portion  33  may be formed by other methods, for example, adhesion. This also applies to an auxiliary peripheral joint portion  44  and an annular joint portion  53 , which will be described later. 
     The main inflation portion  32  takes a major part of the upper body of the occupant P 1 , that is, a part covering from a chest portion PT to the head portion PH in the present embodiment, as a protection target part. The main inflation portion  32  is formed to have a shape and a size that allow the main inflation portion  32  to be deployed and inflated at the outer side of the protection target part. 
     When the deployment and inflation of the main inflation portion  32  are completed, the main inflation portion  32  is in a posture of being inclined with respect to the front-rear direction such that a front side of the main inflation portion  32  is positioned at the front outer side. The inclined posture of the main inflation portion  32  is achieved by, for example, an outer tether (not illustrated). The outer tether is disposed outside the main inflation portion  32 , and spans between the main inflation portion  32  and a member having a high strength in the side portion  17  of the seatback  16 , for example, the side frame portion  18 . The outer tether is formed of a band-shaped fabric piece made of the same material as the main inflation portion  32  and the auxiliary inflation portion  41 . 
     In a rear end portion of the main inflation portion  32 , the gas generator  25  is disposed in a posture of extending substantially in the up-down direction. Further, the bolt  28  is passed through the main inflation portion  32  (the main fabric portion  35 ), whereby the gas generator  25  is locked in a state of being positioned with respect to the main inflation portion  32 . 
     On the other hand, the auxiliary inflation portion  41  is disposed at a position adjacent to the inner side of a front portion of the main inflation portion  32 . The auxiliary inflation portion  41  takes the head portion PH of the occupant P 1  as a protection target part, and is formed to have a shape and a size so as to be able to be deployed and inflated at a position that is the obliquely front outer side of the protection target part. 
     As illustrated in  FIGS.  5  and  6   , the auxiliary inflation portion  41  includes an auxiliary fabric portion  42  adjacent to the main fabric portion  35  of the main inflation portion  32 , and an auxiliary fabric portion  43  disposed on an opposite side of the auxiliary fabric portion  42  from the main inflation portion  32 . The auxiliary fabric portions  42  and  43  may be formed of separate fabric pieces, or may be formed by bending a single fabric piece. A peripheral edge portion of the auxiliary fabric portion  42  and a peripheral edge portion of the auxiliary fabric portion  43  are overlapped and joined by the auxiliary peripheral joint portion  44 . 
     The auxiliary inflation portion  41  includes an annular side portion  45 , an outer main body portion  46 , and an inner main body portion  47  in a state where the deployment and inflation of the auxiliary inflation portion  41  are completed. The annular side portion  45  includes an outer peripheral portion of the auxiliary fabric portion  42  and an outer peripheral portion of the auxiliary fabric portion  43 . The annular side portion  45  has a band shape and constitutes an outer peripheral portion of the auxiliary inflation portion  41 . The outer main body portion  46  is defined by a region of the auxiliary fabric portion  42  surrounded by an outer edge  45   a  of the annular side portion  45 . The inner main body portion  47  is defined by a region of the auxiliary fabric portion  43  surrounded by an inner edge  45   b  of the annular side portion  45 . 
     In the auxiliary inflation portion  41  whose deployment and inflation are completed, a maximum dimension M 1  in a facing direction, which is a direction in which the outer main body portion  46  and the inner main body portion  47  face each other, is set to be smaller than a dimension M 2  in a direction orthogonal to the facing direction. With such a setting, the auxiliary inflation portion  41  has an outer shape like a cushion whose thickness direction is the facing direction. 
     As illustrated in  FIGS.  6  and  7   , the auxiliary inflation portion  41  has the outer main body portion  46  as a joining area Z 1 , and is joined to the main inflation portion  32  in the joining area Z 1 , in a state of being in communication with the main inflation portion  32 . 
     More specifically, an auxiliary communication hole  51 , with which an inside and an outside of the auxiliary inflation portion  41  communicate with each other, is formed in the outer main body portion  46 . In the present embodiment, the auxiliary communication hole  51  is a hole having a circular shape. A main communication hole  52 , with which an inside and an outside of the main inflation portion  32  communicate with each other, is formed in the main fabric portion  35  of the main inflation portion  32  at a position adjacent to the auxiliary communication hole  51 . The main communication hole  52  is a hole having the same or substantially the same shape and size as the auxiliary communication hole  51 . 
     A peripheral portion of the main communication hole  52  in the main fabric portion  35  and a peripheral portion of the auxiliary communication hole  51  in the outer main body portion  46  are overlapped with each other and joined by the annular joint portion  53 . In  FIG.  7   , the annular joint portion  53  is indicated by a broken line thicker than a general broken line. 
     With the annular joint portion  53 , the joining to the main inflation portion  32  at the joining area Z 1  is implemented. The auxiliary inflation portion  41  communicates with the main inflation portion  32  through the main communication hole  52  and the auxiliary communication hole  51 . 
     Combinations of the main communication hole  52 , the auxiliary communication hole  51 , and the annular joint portion  53  are provided at a plurality of positions in the joining area Z 1 . In the present embodiment, four combinations are provided at equal intervals in the front-rear direction and the up-down direction in the joining area Z 1 . Therefore, the main inflation portion  32  and the auxiliary inflation portion  41  communicate with each other via the main communication hole  52  and the auxiliary communication hole  51  of each of the combinations provided at the plurality of positions in the joining area Z 1 . 
     In the two combinations positioned at a front side, a front end portion of each annular joint portion  53  is positioned at a front end portion of the joining area Z 1 . In the two combinations positioned at a rear side, a rear end portion of each annular joint portion  53  is positioned at a rear end portion of the joining area Z 1 . 
     In the two combinations positioned at an upper side, an upper end portion of each annular joint portion  53  is positioned at an upper end portion of the joining area Z 1 . In the two combinations positioned at a lower side, a lower end portion of each annular joint portion  53  is positioned at a lower end portion of the joining area Z 1 . 
     As described above, the auxiliary inflation portion  41  joined to the main inflation portion  32 , whose deployment and inflation are completed, is in a posture of being inclined with respect to the front-rear direction such that a front side of the auxiliary inflation portion  41  is positioned at the front outer side, in the same manner as the main inflation portion  32 . 
     Here, as illustrated in  FIGS.  5  and  7   , in the joining area Z 1 , a distance between the front end portion of the annular joint portion  53  positioned at the foremost position and the rear end portion of the annular joining portion  53  positioned at the rearmost position is defined as a front-rear length L 1  of the joining area Z 1 . In the present embodiment, the distance between the front end portion of the front annular joint portion  53  and the rear end portion of the rear annularj oint portion  53  is the front-rear length L 1  of the joining area Z 1 . The front-rear length L 1  is set to be larger than the maximum dimension M 1  of the auxiliary inflation portion  41 . 
     As illustrated in  FIG.  2   , the airbag module ABM is in a compact storage form by folding a portion of the main inflation portion  32 , which is different from the portion (rear end portion) in which the gas generator  25  is stored, together with the auxiliary inflation portion  41 , the outer tether, and the like. In  FIG.  2   , illustration of the auxiliary inflation portion  41 , the outer tether, and the like is omitted. 
     The airbag module ABM in the storage form is stored in the storage portion  22 . The bolt  28  exposed from the airbag  31  is passed through the side frame portion  18  from the outer side. A portion of the bolt  28  protrudes toward the inner side from the side frame portion  18 , and a nut  29  is fastened to the protruding portion. By this fastening, the gas generator  25  is fixed to the side frame portion  18  together with the main inflation portion  32  from the outer side. 
     The gas generator  25  may be fixed to the side frame portion  18  by a member different from the bolt  28  and the nut  29  described above. When the gas generator  25  only includes the inflator  26 , the inflator  26  may be fixed to the side frame portion  18  by the nut  29  and the bolt  28  fixed to the inflator  26 . 
     The far-side airbag device includes an impact sensor  55  and a control device  56  in addition to the airbag module ABM described above. The impact sensor  55  includes an acceleration sensor or the like, and detects an impact applied to the wheeled vehicle  10  from an obliquely front outer side of the wheeled-vehicle seat  13 . 
     The control device  56  is configured as a circuit. The circuit includes one or more processors that operate in accordance with a computer program (software), one or more dedicated hardware circuits that execute at least a part of various processes, or a combination thereof. The control device  56  controls the actuation of the gas generator  25  based on a detection signal from the impact sensor  55 . In the present embodiment, when the impact sensor  55  detects an impact from the obliquely front outer side, the control device  56  outputs an actuation signal for actuating the gas generator  25  to the gas generator  25 . 
     A seatbelt device (not illustrated) for restraining the occupant P 1  seated on the wheeled-vehicle seat  13  to the wheeled-vehicle seat  13  is provided in the wheeled-vehicle interior. 
     Next, an operation of the present embodiment configured as described above will be described. Effects produced by the operation will also be described. As a precondition, it is assumed that the occupant P 1  is seated on the wheeled-vehicle seat  13  in an appropriate posture, and the occupant P 1  is restrained to the wheeled-vehicle seat  13  by a seatbelt device. 
     Joining of Auxiliary Inflation Portion  41  to Main Inflation Portion  32   
     (1-1) As illustrated in  FIG.  6   , in the present embodiment, the peripheral portion of the main communication hole  52  of the main inflation portion  32  and the peripheral portion of the auxiliary communication hole  51  of the outer main body portion  46  are joined together by the annular joint portion  53 . 
     By such joining, the auxiliary inflation portion  41  can be joined to the main inflation portion  32  in a state where the auxiliary inflation portion  41  communicates with the main inflation portion  32  in the joining area Z 1 . 
     2) As illustrated in  FIGS.  6  and  7   , in the present embodiment, combinations of the main communication hole  52 , the auxiliary communication hole  51 , and the annular joint portion  53  are provided at a plurality of positions in the joining area Z 1 . 
     Therefore, the auxiliary inflation portion  41  can be joined to the main inflation portion  32  at a plurality of positions in the joining area Z 1 . 
     In designing the airbag  31 , a shape and a size of the joining area Z 1  can be changed by changing the positions of the plurality of combinations. 
     At Time of Non-Actuation of Far-Side Airbag Device 
     When the impact sensor  55  illustrated in  FIG.  2    does not detect that an impact is applied to the wheeled vehicle  10  from the obliquely front outer side of the wheeled-vehicle seat  13 , the control device  56  does not output an actuation signal to the gas generator  25 . No inflation gas is ejected from the gas ejection portion  26   a  of the inflator  26 . As illustrated in  FIG.  2   , the airbag module ABM continues to be stored in the storage portion  22  in a storage form. 
     At Time of Actuation of Far-Side Airbag Device 
     Next, a case will be described where an impact is applied to a front side portion of the wheeled vehicle  10  from the obliquely front outer side of the wheeled-vehicle seat  13  due to an oblique collision or the like, as indicated by an arrow in  FIG.  1   , during traveling of the wheeled vehicle  10  or the like. 
     In this case, as illustrated in  FIGS.  5  and  6   , the upper body including the head portion PH of the occupant P 1  tends to move toward the obliquely front outer side due to inertia, which is a side to which an impact is applied, as indicated by an arrow A. At this time, the head portion PH of the occupant P 1  tends to rotate about an axis L 2  of the neck portion PN as indicated by an arrow B. 
     (3-1) On the other hand, in the far-side airbag device of the present embodiment, when the impact sensor  55  in  FIG.  2    detects that the impact is applied, the control device  56  outputs the actuation signal to the gas generator  25  in response to the detection signal. When an inflation gas is ejected from the gas ejection portion  26   a  of the inflator  26  in response to the actuation signal, the inflation gas is supplied to the main inflation portion  32  of the airbag  31  in the storage form. 
     When the inflation gas is supplied to the main inflation portion  32 , an internal pressure of the main inflation portion  32  increases. The main inflation portion  32  is inflated while being unfolded, that is, while being deployed. 
     During the deployment and inflation, the main inflation portion  32  presses the seat pad  19  near the storage portion  22  in  FIG.  2    together with the auxiliary inflation portion  41 , the outer tether, and the like, and breaks the seat pad  19  at the breakage-expected portion  24 . Thereafter, the supply of the inflation gas is continued, so that the main inflation portion  32  exits to the outside of the storage portion  22  through the broken portion together with the auxiliary inflation portion  41  and the like in a state where a portion thereof fixed to the side frame portion  18  remains in the storage portion  22 . The main inflation portion  32  is deployed and inflated toward a front upper side, at the outer side of the upper body of the occupant P 1 , that is, between the wheeled-vehicle seats  13  and  14 , as illustrated in  FIGS.  3  and  4   . Therefore, the upper body of the occupant P 1  is caught by the main inflation portion  32 , and is prevented from moving toward the obliquely front outer side, so that the upper body can be protected from the impact. 
     (3-2) As illustrated in  FIGS.  6  and  7   , the main inflation portion  32  and the auxiliary inflation portion  41  communicate with each other via the main communication hole  52  and the auxiliary communication hole  51 . Therefore, a part of the inflation gas supplied to the main inflation portion  32  flows into the auxiliary inflation portion  41  through the main communication hole  52  and the auxiliary communication hole  51  during deployment and inflation of the main inflation portion  32 . 
     In particular, in the present embodiment, the combinations of the main communication hole  52 , the auxiliary communication hole  51 , and the annular joint portion  53  are provided at a plurality of positions in the joining area Z 1 . Therefore, a part of the inflation gas passing through the main inflation portion  32  flows into the auxiliary inflation portion  41  through the main communication hole  52  and the auxiliary communication hole  51  of each of the combinations at the plurality of positions in the joining area Z 1 . 
     With the inflation gas flowing in as described above, as illustrated in  FIGS.  5  and  6   , the auxiliary inflation portion  41  is deployed and inflated at the position adjacent to the inner side of the front portion of the main inflation portion  32 , which is the obliquely front outer side of the head portion PH of the occupant P  1 . 
     Therefore, even if the head portion PH of the occupant P 1  is about to rotate about the axis L 2  of the neck portion PN, the head portion PH is caught by the auxiliary inflation portion  41  and the main inflation portion  32 . The head portion PH can be protected from the impact by preventing the rotation of the head portion PH about the axis L 2 , that is, by restraining the head portion PH. 
     (3-3) In particular, in the present embodiment, the outer main body portion  46  is defined as the joining area Z 1 , and the auxiliary inflation portion  41  is joined to the main inflation portion  32  in the joining area Z 1 . 
     In the auxiliary inflation portion  41  whose deployment and inflation are completed, the maximum dimension M 1  of the outer main body portion  46  and the inner main body portion  47  in the facing direction is smaller than the dimension M 2  of the outer main body portion  46  and the inner main body portion  47  in the direction orthogonal to the facing direction. 
     Therefore, as described above, when the outer main body portion  46  is set as the joining area Z 1 , the joining area Z 1  can be wider than when the annular side portion  45  is set as the joining area Z 1 . When the auxiliary inflation portion  41  is joined to the main inflation portion  32  in the wide joining area Z 1 , the posture of the auxiliary inflation portion  41  with respect to the main inflation portion  32  is stabilized. 
     A phenomenon in which the auxiliary inflation portion  41  rotates toward the front outer side about a joint portion with the main inflation portion  32  due to contact with the head portion PH is prevented. Therefore, the performance of preventing the rotation of the head portion PH about the axis L 2  of the neck portion PN can be prevented from being lowered due to the rotation of the auxiliary inflation portion  41 . 
     (3-4) Further, in the present embodiment, the front-rear length L 1  (&lt; M 2 ) of the joining area Z 1 , which is a region where the auxiliary inflation portion  41  is actually joined to the main inflation portion  32 , is compared with the maximum dimension M 1  of the auxiliary inflation portion  41 . The maximum dimension M 1  is set to be smaller than the front-rear length L 1  (see  FIG.  5   ). 
     Therefore, the auxiliary inflation portion  41  is joined to the main inflation portion  32  in the joining area Z 1  that is wider than when the annular side portion  45  is set as the joining area Z 1 , and the posture of the auxiliary inflation portion  41  with respect to the main inflation portion  32  is stabilized. 
     Therefore, it is possible to prevent a phenomenon in which the auxiliary inflation portion  41  rotates about the j oint portion with the main inflation portion  32  due to contact with the head portion PH. Accordingly, the performance of preventing the rotation of the head portion PH about the axis L 2  of the neck portion PN can be prevented from being lowered due to the rotation of the auxiliary inflation portion  41 . 
     (3-5) Further, in the present embodiment, the auxiliary inflation portion  41  is deployed and inflated at a front side in a movement direction of the head portion PH. In addition, the main inflation portion  32  and the auxiliary inflation portion  41 , whose deployment and inflation are completed, are inclined with respect to the front-rear direction such that the front side of the main inflation portion  32  and the front side of the auxiliary inflation portion  41  are positioned at the front outer side. Therefore, a boundary portion between the main inflation portion  32  and the auxiliary inflation portion  41  is positioned at the front side in the movement direction of the head portion PH. 
     Therefore, the head portion PH is caught by both the main fabric portion  35  of the main inflation portion  32  and the auxiliary fabric portion  42  of the auxiliary inflation portion  41 , and the rotation of the head portion PH about the neck portion PN can be further prevented. 
     Other Effects 
     (4-1) The main inflation portion  32  is deployed and inflated at the outer side of the upper body of the occupant P 1 . Therefore, when an impact is applied to the side wall portion  12  from the outer side due to a side collision or the like, the upper body of the occupant P 1  tends to move toward the side to which the impact is applied, but the upper body is caught by the main inflation portion  32 , and the occupant P 1  can be protected from the impact. 
     The above-described embodiment may be modified as follows. The above-described embodiment and the following modifications can be implemented in combination with each other within a technically consistent range. 
     Regarding Airbag  31   
     As illustrated in  FIG.  8   , the main inflation portion  32  may take a posture along the front-rear direction in a state in which the deployment and inflation thereof are completed. In this case, a posture (inclination with respect to the front-rear direction) of the main inflation portion  32  and the auxiliary inflation portion  41  with respect to the upper body of the occupant P 1 , particularly, with respect to the head portion PH, is different from that in the above-described embodiment. However, also in this case, as in the above-described embodiment, the head portion PH is caught by the main inflation portion  32  and the auxiliary inflation portion  41 , and the effect of preventing the rotation of the head portion PH about the neck portion PN is obtained. 
     The shape or size of the main inflation portion  32  may be changed, and the protection target part of the occupant P 1  by the main inflation portion  32  may be enlarged, reduced, or changed. 
     The main inflation portion  32  may be substantially entirely inflated as in the above-described embodiment, and may partially include a non-inflation portion that is not supplied with the inflation gas and is not inflated. 
     The number of combinations of the main communication hole  52 , the auxiliary communication hole  51 , and the annular joint portion  53  may be changed to one. In this case, a region of the auxiliary fabric portion  42  surrounded by the annular joint portion  53  is the joining area Z 1 . 
     In addition, the number of combinations may be changed to a number different from the number (four) in the above-described embodiment on condition that the number of combinations is plural. 
     In the case where four combinations of the main communication hole  52 , the auxiliary communication hole  51 , and the annular joint portion  53  are provided, the combinations may be arranged in a mode different from that in the above-described embodiment. 
     The shape of the main communication hole  52  and the auxiliary communication hole  51  may be changed to a shape different from the circular shape, for example, a polygonal shape such as a quadrangular shape, or an elliptical shape. 
     The main communication hole  52  and the auxiliary communication hole  51  may be an elongated hole, a slit, or the like. 
     Control Device  56   
     The control device  56  may be changed to a specification for outputting an actuation signal to the gas generator  25  when it is predicted that an impact is to be applied to the wheeled vehicle  10  from the obliquely front outer side of the wheeled-vehicle seat  13 . 
     Application Place of Far-Side Airbag Device 
     The far-side airbag device may be applied to the wheeled-vehicle seat  14  instead of or in addition to the wheeled-vehicle seat  13 . 
     The far-side airbag device may be applied not only to front seats (a driver’s seat and a front passenger seat) of the wheeled vehicle  10 , but also to rear seats (seats in the second and subsequent rows). 
     In a case of a wheeled-vehicle in which a wheeled-vehicle seat is disposed in a posture in which the seatback  16  faces a side different from the front side, for example, a lateral side, the far-side airbag device is also applicable to these wheeled-vehicle seats. 
     In a case of a wheeled vehicle in which three or more wheeled-vehicle seats are arranged side by side in the width direction, the far-side airbag device is also applicable to these wheeled-vehicle seats. 
     Others 
     The airbag device is not limited to the far-side airbag device, and a normal side airbag device may be applied. In this case, the airbag module ABM is stored in the side portion  17  of the seatback  16  of the wheeled-vehicle seat  13 , which is farther from the adjacent wheeled-vehicle seat  14 , that is, closer to the adjacent side wall portion  11 ; and the airbag module ABM is stored in the side portion  17  of the seatback  16  of the wheeled-vehicle seat  14 , which is farther from the adjacent wheeled-vehicle seat  13 , that is, closer to the adjacent side wall portion  12 . 
     The wheeled vehicle to which the airbag device is applied includes not only private cars but also various industrial wheeled vehicles. 
     The airbag device is also applicable as an airbag device mounted on a vehicle seat in a vehicle different from a wheeled vehicle, for example, an aircraft and a ship.