Patent Publication Number: US-11034324-B2

Title: Airbag device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from prior Japanese patent application No. 2018-062486, filed on Mar. 28, 2018, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to an airbag device including an airbag accommodated with being folded in an accommodation part to be arranged at an outer side of a vehicle interior and configured to protrude toward an outside of a vehicle upon inflation. 
     BACKGROUND ART 
     Since an airbag device to be arranged at an outer side of a vehicle interior is mounted at the outer side of the interior, rainwater and the like may be introduced into a case. Considering this point, in the related art, an airbag device for pedestrian has been suggested in which a wrapping material is wrapped around a folding completion body configured by folding an airbag and a case is provided with a water-draining passage for discharging the rainwater and the like introduced into the case (for example, refer to Patent Document 1). 
     Patent Document 1: JP-A-2008-80830 
     However, the wrapping material for wrapping the folding completion body is formed with a slit for rupturing a surrounding portion thereof at an early stage of deployment and inflation of the airbag so as to rapidly deploy the airbag. Therefore, the rainwater and the like may be introduced into the folding completion body from the slit. 
     The present invention has been made in view of the above situations, and an object thereof is to provide an airbag device capable of rapidly deploying an airbag and correctly suppressing rainwater from being introduced into a folding completion body. 
     SUMMARY OF INVENTION 
     According to an aspect of the invention, there is provided an airbag device comprising: an airbag accommodated with being folded in an accommodation part to be arranged at an outer side of a vehicle interior and configured to protrude toward an outside of a vehicle upon inflation, the airbag accommodated in the accommodation part in a state where a wrapping material formed of a flexible sheet body is wrapped around a folding completion body formed by folding the air bag, wherein the accommodation part has an opening for protrusion at an upper side so as to enable the airbag to protrude therefrom, wherein the wrapping material is wrapped over an entire circumference around the folding completion body and a region thereof configured to cover an upper of the folding completion body has a double structure of an outer part and an inner part, wherein the outer part has slits that are intermittently formed substantially along an axial direction of the folding completion body so that peripheral edges thereof can be ruptured upon deployment and inflation of the airbag, and wherein the inner part is configured to cover a lower of the slits and is configured so that a terminal, which is an edge side distant from a region configuring the outer part of the wrapping material, is located below a central line extending substantially in a horizontal direction from a sectional center of the folding completion body. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view of a vehicle in which an airbag device for pedestrian of an illustrative embodiment of the present invention is mounted. 
         FIG. 2  is a schematic enlarged longitudinal sectional view of the airbag device for pedestrian of the illustrative embodiment taken along a front and rear direction, depicting an inflator. 
         FIG. 3  is a schematic enlarged longitudinal sectional view of the airbag device for pedestrian of the illustrative embodiment taken along a right and left direction, depicting the inflator. 
         FIG. 4  is a plan view of a case that is used for the airbag device for pedestrian of the illustrative embodiment. 
         FIG. 5  is a front view of the case shown in  FIG. 4 . 
         FIG. 6  is a plan view depicting a flatly-deployed state of an airbag that is used for the airbag device for pedestrian of the illustrative embodiment. 
         FIG. 7  is a bottom view depicting the flatly-deployed state of the airbag of  FIG. 6 . 
         FIG. 8  is a partially enlarged bottom view depicting an attachment piece part of the airbag of  FIG. 6 . 
         FIG. 9  is a sectional view taken along a line IX-IX of  FIG. 8 . 
         FIG. 10  is a longitudinal sectional view depicting a state where the attachment piece part is attached to the case in the airbag device for pedestrian of the illustrative embodiment. 
         FIG. 11  is a plan view depicting that base materials configuring the airbag of  FIG. 6  are set in array. 
         FIG. 12  is a plan view depicting a flatly-deployed state of a wrapping material that is used for the airbag device for pedestrian of the illustrative embodiment. 
         FIGS. 13A and 13B  are schematic views illustrating a process of wrapping the wrapping material around a folding completion body formed by folding the airbag. 
         FIGS. 14A and 14B  are schematic views illustrating the process of wrapping the wrapping material around the folding completion body formed by folding the airbag, depicting a next process of  FIGS. 13A and 13B . 
         FIG. 15  is a schematic partially enlarged sectional view depicting discharge of rainwater when the rainwater has been introduced into the wrapping material from a slit, in the airbag device for pedestrian of the illustrative embodiment. 
         FIG. 16  is a schematic partially enlarged sectional view depicting discharge of the rainwater when the rainwater has been introduced into the wrapping material in the airbag device for pedestrian of the illustrative embodiment. 
         FIG. 17  is a schematic enlarged longitudinal sectional view of the airbag device for pedestrian for which a wrapping material of another illustrative embodiment of the present invention is used. 
         FIG. 18  is a plan view depicting a flatly-deployed state of the wrapping material that is used for the airbag device for pedestrian of  FIG. 17 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an illustrative embodiment of the present invention will be described with reference to the drawings. In the illustrative embodiment, as an airbag device to be arranged at an outer side of a vehicle interior, an airbag device M for pedestrian (hereinafter, abbreviated as “airbag device M”) that is to be mounted in the vicinity of a rear end  15   c  of a hood panel  15  of a vehicle V is exemplified. 
     As shown in  FIGS. 1 and 2 , the airbag device M is arranged at a position that is adjacent to a rear side of the rear end  15   c  of the hood panel  15  and is a substantial center in a right and left direction of the vehicle V between left and right front pillars  5 L,  5 R. Meanwhile, in the specification, the front and rear direction, the upper and lower direction and the right and left direction coincide with the front and rear direction, the upper and lower direction and the right and left direction of the vehicle, unless particularly mentioned. 
     In the illustrative embodiment, a sensor (not shown) capable of detecting a collision with a pedestrian is arranged at a front bumper  6  (refer to  FIG. 1 ) of the vehicle V. When an activation circuit (not shown) to which a signal from the sensor is to be input detects a collision between the vehicle V and a pedestrian on the basis of the signal from the sensor, it activates an inflator  35  of the airbag device M. 
     As shown in  FIG. 1 , the hood panel  15  is arranged to cover the upper of an engine room of the vehicle V, and is coupled to a body  1  of the vehicle V to be openable and closable forward by hinge parts (not shown) arranged in the vicinity of the rear end  15   c  at both left and right edge sides. In the illustrative embodiment, the hood panel  15  is made of a steel plate, an aluminum (aluminum alloy) plate material or the like, and has an outer panel  15   a  positioned at an upper surface-side and an inner panel  15   b  positioned at a lower surface-side and having higher strength than the outer panel  15   a , as shown in  FIG. 2 . As shown in  FIG. 1 , the rear end  15   c  of the hood panel  15  is curved with respect to the right and left direction so that a center in the right and left direction is positioned at the front and both left and right ends are positioned at the rear, in conformity to a front windshield  4  (which will be described later). 
     As shown in  FIGS. 1 and 2 , a cowl  7  having a cowl panel  7   a  provided at the body  1 -side and having high stiffness and a cowl louver  7   b  provided above the cowl panel  7   a  and made of synthetic resin is arranged at the rear of the hood panel  15 . The cowl louver  7   b  is arranged so that a rear end thereof is to continue to a lower part  4   a  of the front windshield  4 . The cowl  7  is also curved with respect to the right and left direction so that a center in the right and left direction is positioned at the front and both left and right ends are positioned at the rear, in conformity to the curved shape of the rear end  15   c  of the hood panel  15  (refer to  FIG. 1 ). Also, as shown in  FIG. 1 , wipers  8  are arranged at parts of the cowl  7 . The wipers  8  are arranged to protrude upward from the cowl louver  7   b  (refer to the dashed-two dotted line in  FIG. 2 ). The front pillars  5 L,  5 R are arranged at left and right outer sides of the front windshield  4 . 
     As shown in  FIGS. 2 and 3 , the airbag device M includes an airbag  50 , an inflator  35  configured to supply an inflation gas to the airbag  50 , a case  20  as an accommodation part configured to accommodate therein the airbag  50  and the inflator  35 , an airbag cover  30  configured to cover the folded airbag  50 , attachment brackets  120  configured to attach attachment piece parts  75  (which will be described later) of the airbag  50  to the case  20 , and a wrapping material  97  wrapped around a folding completion body  130  formed by folding the airbag  50 . 
     The case  20  as the accommodation part is made of a plate, has a substantial box shape having a bottom wall part  21  and a substantially square tube-shaped peripheral wall part  25  extending upward from the bottom wall part  21  and having an opened upper end, and is configured to enable the airbag  50  being inflating to protrude from an opening  20   a  for protrusion formed at the upper end, as shown in  FIGS. 2, 4 and 5 . In the illustrative embodiment, the bottom wall part  21  is formed to be slightly inclined rearward and downward so that a rear end  21   b  is located at a position slightly lower than a front end  21   a  in a state where the airbag is mounted to the vehicle (refer to  FIGS. 2 and 15 ). Also, the bottom wall part  21  has a central portion  21 C arranged substantially in the right and left direction, and a left portion  21 L and a right portion  21 R inclined downward toward left and right outer sides, while keeping the inclined state relative to the front and rear direction (refer to  FIG. 5 ). That is, the case  20  of the illustrative embodiment is configured so that the bottom wall part  21  is inclined rearward and downward and the left and right regions are inclined downward toward the outer sides. Also, the bottom wall part  21  is formed with attachment holes  22  into which attachment bolts  44  for attaching the inflator  35  and attachment bolts  122  for attaching attachment piece parts  110  of the airbag  50  are inserted and fixed with nuts  47 ,  124  (refer to  FIG. 4 ). Also, the bottom wall part  21  is formed with discharge holes  23  through which rainwater and the like introduced into the case  20  can be discharged to an outside. As shown in  FIG. 4 , in the illustrative embodiment, the discharge holes  23  have a long hole shape of which a longitudinal direction is substantially the front and rear direction, respectively, are formed in a rear region of a center in the front and rear direction of the bottom wall part  21 , and are arranged in plural (six, in the illustrative embodiment) in the right and left direction from the central portion  21 C over the left portion  21 L and the right portion  21 R. The peripheral wall part  25  is formed with attachment piece parts  25   a , which are attached to the cowl panel  7   a  and protrude outward in the front and rear direction and the right and left direction. The attachment piece parts  25   a  are formed in plural. 
     The airbag cover  30  is made of soft synthetic resin such as polyolefin-based thermoplastic elastomer (TPO), and has a door part  31  arranged to cover the opening  20   a  for protrusion formed at the upper end of the case  20  and configured to be pushed and opened by the airbag  50  upon deployment and inflation of the airbag  50  (refer to  FIG. 2 ). Although not shown in detail, the airbag cover  30  is attached at a predetermined place to the peripheral wall part  25  of the case  20  by an attachment means (not shown). 
     The inflator  35  includes an inflator main body  36  of a cylinder type having a substantially circular column outer shape, and an attachment bracket  40  for attaching the inflator main body  36  to the case  20 . 
     As shown in  FIGS. 2 and 3 , the inflator main body  36  has a substantially circular column outer shape and is arranged at a substantially central position in the front and rear direction and the right and left direction of a lateral inflation part  53  (which will be described later) in the bag main body  51  of the airbag  50 , in a state where an axial direction is aligned in the right and left direction (refer to  FIGS. 6 and 7 ). As shown in  FIG. 3 , the inflator main body  36  has a gas discharge port  37  for discharging the inflation gas at one axial end (a left end  36   a ), and is electrically connected to the activation circuit via a lead wire (not shown) extending from the other axial end (a right end  36   b ). 
     As shown in  FIGS. 2 and 3 , the attachment bracket  40  for attaching the inflator main body  36  to the case  20  has a holding part  41  for holding the inflator main body  36  and a plurality of (three, in the illustrative embodiment) attachment bolts  44  protruding downward from the holding part  41 . The holding part  41  is made of a plate, has a band shape extending substantially in the right and left direction (the axial direction of the inflator main body  36 ) so as to support a lower surface-side of the inflator main body  36 , and includes support piece parts  42  protruding toward both front and rear sides and configured to support the inflator main body  36  at a plurality of places (three places, in the illustrative embodiment) along the right and left direction. Each of the support piece parts  42  is inclined to extend upward with tip ends being directed outward in the front and rear direction from front and rear edge portions of the holding part  41  so as to support an outer peripheral surface of the inflator main body  36  and is symmetrical with respect to the front and rear direction (refer to  FIG. 2 ). In the illustrative embodiment, the support piece part  42  is formed at a position corresponding to the attachment bolt  44 . The attachment bolts  44  are formed to protrude downward at three places of both left and right ends and a substantial center in the right and left direction of the holding part  41 . In the illustrative embodiment, the attachment bracket  40  is configured to attach the inflator main body  36  by winding clamps  45  from the outer periphery-side in a state where the inflator main body  36  is held in the holding part  41 . In the illustrative embodiment, the clamps  45  are arranged at two places of left and right ends. 
     The inflator  35  has a configuration where the inflator main body  36  and the holding part  41  of the attachment bracket  40  are accommodated in the airbag  50  with the attachment bolts  44  protruding outward from insertion holes  57  and attachment holes  61  (which will be described later) in a state where the inflator main body  36  is attached to the attachment bracket  40  by using the clamps  45  (refer to  FIG. 3 ). The inflator  35  is attached to the bottom wall part  21  of the case  20  in a state where the inflator main body  36  and the holding part  41  of the attachment bracket  40  are accommodated in the airbag  50 . Specifically, as shown in  FIGS. 3 and 4 , the inflator  35  is attached to the central portion  21 C of the bottom wall part  21 . That is, the attachment bolts  44  protruding from the wrapping material  97  are arranged to protrude from the central portion  21 C of the bottom wall part  21  of the case  20  and are fixed by the nuts  47 , so that the inflator  35  is attached to the case  20  together with the airbag  50  (refer to  FIG. 2 ). Also, in the illustrative embodiment, the inflator  35  is accommodated in the airbag  50  with the outer peripheries of the inflator main body  36  and the holding part  41  of the attachment bracket  40  being covered by a cylindrical inner tube  82  having flexibility (refer to  FIGS. 2, 3 and 7 ). 
     As shown in  FIGS. 6 and 7 , the airbag  50  has a bag main body  51  configured to inflate by enabling the inflation gas to flow therein, attachment piece parts  75  for attaching a vehicle body-side wall part  51   a  (which will be described later) of the bag main body  51  to the case  20 , and an inner tube  82  configured to cover the outer periphery-side of the inflator  35  in the bag main body  51 . 
     The bag main body  51  has a substantial U-shape, which is wide in the right and left direction, as seen from the front, upon completion of the inflation, and includes a lateral inflation part  53  to be arranged substantially in the right and left direction so as to conform to the lower part  4   a  of the front windshield  4 , and longitudinal inflation parts  65 L,  65 R extending rearward from both ends of the lateral inflation part  53  and configured to cover lower parts  5   a  of front surfaces of the left and right front pillars  5 L,  5 R. The bag main body  51  has a pedestrian-side wall part  51   b  to be positioned at an upper surface-side and a vehicle body-side wall part  51   a  to be positioned at a lower surface-side so as to face the pedestrian-side wall part  51   b  upon completion of the inflation, and outer peripheral surfaces of the pedestrian-side wall part  51   b  and the vehicle body-side wall part  51   a  are joined (sewn) to each other over an entire circumference, so that the bag main body  51  has a bag shape. 
     In the illustrative embodiment, upon completion of the inflation, the lateral inflation part  53  is configured to cover an upper surface-side (front surface-side) of a region from the rear end  15   c -side of the hood panel  15  to the lower part  4   a -side of the front windshield  4  via the cowl  7 , including the wipers  8 , too. In the bag main body  51  of the illustrative embodiment, the vehicle body-side wall part  51   a  is formed at a position around the lateral inflation part  53  with an opening part  55  for insertion for inserting therein the inflator  35 . 
     As shown in  FIG. 7 , the opening part  55  for insertion has a slit  56  for insertion formed in the vehicle body-side wall part  51   a , insertion holes  57  for inserting the attachment bolts  44  of the inflator  35 , and a cover panel  59  configured to block the slit  56  for insertion from an outer periphery-side. The slit  56  for insertion is provided so as to insert the inflator main body  36 , and has a linear shape substantially along the right and left direction so as to follow an axial direction of the inflator main body  36 . The slit  56  for insertion has a length dimension set smaller than a length dimension of the inflator main body  36  (refer to  FIG. 7 ). The insertion holes  57  are provided so as for the attachment bolts  44  of the inflator  35  to protrude therefrom, and are formed at three places along the right and left direction, in correspondence to the attachment bolts  44 . In the illustrative embodiment, the insertion holes  57  are formed in a front region of the slit  56  for insertion in the state where the bag main body  51  is flatly deployed. The cover panel  59  is formed by a flexible sheet body, is configured to block the slit  56  for insertion at the outer periphery-side of the vehicle body-side wall part  51   a  and has a substantially rectangular outer shape of which a width in the right and left direction is larger. The cover panel  59  has a rear end  59   b  that is joined to the vehicle body-side wall part  51   a  by a joining portion  60  formed over a substantially entire region in the right and left direction at a rear position of the slit  56  for insertion, and a front end  59   a  having attachment holes  61  for enabling the attachment bolts  44  of the inflator  35  to protrude therefrom, which are arranged in correspondence to the insertion holes  57 . 
     Also, in the bag main body  51 , a rear-side center tether  67 , a front-side center tether  68  and end-side tethers  69  ( 69 L,  69 R) configured to couple the pedestrian-side wall part  51   b  and the vehicle body-side wall part  51   a  so as to regulate a spaced distance between the pedestrian-side wall part  51   b  and the vehicle body-side wall part  51   a  upon completion of the inflation are arranged (refer to  FIGS. 6 and 7 ). The rear-side center tether  67  is arranged in a rear region of the center in the front and rear direction over a region from the lateral inflation part  53  to the left and right longitudinal inflation parts  65 L,  65 R, in a gentle curve shape over an entire length so as to follow a rear edge of the flatly-deployed bag main body  51 . As shown in  FIG. 11 , the rear-side center tether  67  is formed by two base fabrics  90  for tether of a vehicle body-side part  90   a  to be arranged at the vehicle body-side wall part  51   a -side and a pedestrian-side part  90   b  to be arranged at the pedestrian-side wall part  51   b -side. The front-side center tether  68  is arranged in a front region of the center of the lateral inflation part  53  in the front and rear direction, in a substantially linear shape along the right and left direction so as to substantially follow a front edge of the flatly-deployed bag main body  51 . As shown in  FIG. 11 , the front-side center tether  68  is also formed by two base fabrics  91  for tether of a vehicle body-side part  91   a  to be arranged at the vehicle body-side wall part  51   a -side and a pedestrian-side part  91   b  to be arranged at the pedestrian-side wall part  51   b -side. The end-side tethers  69  ( 69 L,  69 R) are respectively arranged at front positions of the respective longitudinal inflation parts  65 L,  65 R, in a region between the front-side center tether  68  and the rear-side center tether  67 . The end-side tethers  65  ( 65 L,  65 R) are also arranged to be bilaterally symmetric, in a substantially linear shape along the right and left direction. As shown in  FIG. 11 , the end-side tethers  69  ( 69 L,  69 R) are respectively formed by two base fabrics  92  for tether of a vehicle body-side part  92   a  to be arranged at the vehicle body-side wall part  51   a -side and a pedestrian-side part  92   b  to be arranged at the pedestrian-side wall part  51   b -side. 
     The attachment piece part  75  for attaching the vehicle body-side wall part  51   a  of the bag main body  51  to the case  20  is configured by a flexible sheet body, as a separate body from the bag main body  51 , and is joined (sewn) to the vehicle body-side wall part  51   a , as shown in  FIGS. 8 and 9 . The attachment piece part  75  is attached to the bottom wall part  21  of the case  20  by using the attachment bracket  120 . In the illustrative embodiment, as shown in  FIG. 7 , the attachment piece parts  75  ( 75 L,  75 R) are arranged at two positions, which are substantially bilaterally symmetric, between the opening part  55  for insertion and the respective end-side tethers  69 L,  69 R in the flatly-deployed state of the bag main body  51 . Also, each attachment piece part  75  is arranged at a position, which is a substantial center in the front and rear direction, between the front-side center tether  68  and the rear-side center tether  67 . In the illustrative embodiment, the respective attachment piece parts  75  are attached in regions of the left portion  21 L and the right portion  21 R of the bottom wall part  21 . 
     As shown in  FIGS. 8 and 9 , each attachment piece part  75  has an attachment piece main body  76 , and a reinforcement piece part  79  arranged between the attachment piece main body  76  and the vehicle body-side wall part  51   a . The attachment piece main body  76  has a substantially rectangular outer shape, and a front edge  76   a  and a rear edge  76   b  thereof are joined (sewn) to the vehicle body-side wall part  51   a  via the reinforcement piece part  79 . The attachment piece main body  76  is formed with through-holes  77  in which the attachment bolts  122  (which will be described later) provided to the attachment bracket  120  can be inserted. The two through-holes  77  are aligned side by side in the right and left direction at a substantial center of the attachment piece main body  76  in the front and rear direction. The reinforcement piece part  79  is formed to be larger than the attachment piece main body  76  by one dimension, and an outer peripheral edge thereof, which is an outer side of the attachment piece main body  76 , is joined (sewn) to the vehicle body-side wall part  51   a  over an entire circumference. As shown with the dashed-two dotted line in  FIG. 9  and  FIG. 10 , the attachment piece part  75  is configured so that the attachment bolts  122  of the attachment bracket  120  are arranged to protrude from the through-holes  77  and an attachment plate  121  of the attachment bracket  120  is arranged between the attachment piece main body  76  and the reinforcement piece part  79 . 
     The inner tube  82  configured to cover the outer periphery-side of the inflator main body  36  is configured by a flexible sheet body and has a cylindrical shape, as shown in  FIG. 7 . In the illustrative embodiment, the inner tube  82  has a configuration where a right end  82   b  is configured as a base end in a flatly-deployed state, the inflator  35  is inserted from the right end  82   b , both left and right ends are opened, a left end  82   a , which is a tip end, is branched and the left end  82   a  is provided with two outlets  83 A,  83 B for enabling the inflation gas, which is to be discharged from the inflator main body  36 , to flow out toward the left and the oblique right upper. The inner tube  82  is formed with insertion holes  84  from which the attachment bolts  44  of the attachment bracket  40  holding the inflator main body  36  are to protrude (refer to  FIG. 11 ). 
     As shown in  FIG. 11 , the airbag  50  has a vehicle body-side base fabric  87  configuring the vehicle body-side wall part  51   a  of the bag main body  51 , a pedestrian-side base fabric  88  configuring the pedestrian-side wall part  51   b , the base fabrics  90 ,  91 ,  92  for tether configuring the rear-side center tether  67 , the front-side center tether  68  and the end-side tether  69 , a base fabric  93  for tube configuring the inner tube  82 , the cover panel  59 , and the attachment piece main body  76  and reinforcement piece part  79  configuring the attachment piece part  75 . In the meantime, the base fabric (material) is formed by cutting a coated fabric, which is obtained by applying a coating agent for gas leakage prevention to a surface of a woven fabric formed by weaving polyamide yarn, polyester yarn or the like, into a predetermined shape. 
     The wrapping material  97  wrapped over the entire circumference around the folding completion body  130  formed by folding the airbag  50  is formed by a flexible sheet body. In the illustrative embodiment, like the base material configuring the airbag  50 , the wrapping material  97  is formed by a coated fabric, which is obtained by applying a coating agent for gas leakage prevention to a surface of a woven fabric formed by weaving polyamide yarn, polyester yarn or the like. 
     In the illustrative embodiment, the wrapping material  97  is wrapped around the folding completion body  130 , which is formed by folding the airbag  50 , into a substantial rod shape substantially along the right and left direction, which is a longitudinal direction, in a state where the inflator  35  is accommodated (refer to  FIGS. 2, 15 and 16 ). The wrapping material  97  has a substantially rectangular outer shape in the flatly-deployed state (refer to  FIG. 12 ), a width dimension in the longitudinal direction, which is substantially the same as the length dimension of the folding completion body  130 , and a double structure having an inner part  112  arranged at an inner side and an outer part  98  configured to cover an outer side of the inner part  112  in a state where the wrapping material is wrapped around the folding completion body  130  (refer to  FIGS. 2, 15 and 16 ). As shown in  FIG. 12 , the outer part  98  and the inner part  112  have the same width dimension in the longitudinal direction (the width dimension of the folding completion body  130  in the axial direction) and are configured to continue in the width direction. 
     The outer part  98  has a main body part  99  configured to cover the outer periphery-side of the folding completion body  130  over the entire circumference, and attachment piece parts  110 ,  110  protruding from edge portions (a left edge  99   c  and a right edge  99   d ) of the main body part  99  in the longitudinal direction. Each attachment piece part  110  is formed at a substantial center of the main body part  99  in the width direction (in the front and rear direction in the flatly-deployed state), and is formed at a tip end with two insertion holes  110   a  in which the attachment bolts  122  for attaching the attachment piece part  75  of the airbag  50  are to be inserted. Both ends (a front end  99   a  and a rear end  99   b  in the flatly-deployed state) of the main body part  99  in the width direction are formed with insertion holes  101 F,  101 R,  102 F,  102 R in which the attachment bolts  44  for attaching the inflator  35  and the attachment bolts  122  for attaching the attachment piece parts  75  of the airbag  50  are to be inserted. The insertion holes  101 F,  101 R are respectively formed in a central region of the outer part  98  in the right and left direction three by three, in correspondence to the attachment bolts  44 , and the insertion holes  102 F,  102 R are respectively formed at both left and right ends of the outer part  98  two by two, in correspondence to the attachment bolts  122 . Also, a plurality of openings  104  formed to have a substantial square shape by cutting is arranged in the longitudinal direction (the right and left direction) of the main body part  99  in the vicinity of a boundary between the outer part  98  and the inner part  112  (in the vicinity of an end portion of the inner part  112 -side and in the vicinity of the front end  99   a  in the flatly-deployed state). Specifically, the openings  104  are formed so as to discharge the rainwater, which is to be introduced between the wrapping material  97  and the folding completion body  130  when mounted to the vehicle, to an outside. In the illustrative embodiment, one opening  104  between the insertion holes  101 F and two openings  104  between the insertion hole  101 F and the insertion hole  102 F are arranged, so that a total of six openings  104  are arranged. That is, the openings  104  are formed so that the outer peripheral surface of the folding completion body  130  is exposed, in the region extending from the outer part  98  to cover a lower side of the folding completion body  130  when mounted to the vehicle. Also, an end portion (the rear end  99   b  in the flatly-deployed state) of the outer part  98 , which is distant from the inner part, is formed in regions between the insertion holes  101 R (regions to cover the lower of the front end  99   a  of the outer part  98 ) with cutout portions (openings)  105  formed by cutting an end edge (so as to be concave forward) at positions (refer to B of  FIG. 14 ) overlapping the openings  104  in the state where the outer part  98  is wrapped around the folding completion body  130 . 
     A substantial center of the outer part  98  in the width direction is intermittently formed with slits  107  along the longitudinal direction (the axial direction of the folding completion body  130 ). The slits  107  are formed to have intervals (coupling portions) therebetween by intermittently making linear cut lines at the outer part  98 , and are arranged at an upper position (the opening  20   a  for protrusion of the case  20 ) of the folding completion body  130  in the state where the outer part  98  is accommodated with being wrapped around the folding completion body  130  in the case  20  (refer to  FIGS. 2 and 15 ). The slits  107  are ruptured at peripheral edge portions (the portions between the slits  107 ; the coupling portions) upon the inflation of the airbag  50 . The slits  107  are configured so that end portions  107   a ,  107   b  are located in the regions of the attachment piece parts  101  beyond the main body part  99  (refer to  FIG. 12 ). 
     The inner part  112  is arranged to extend forward continuously from the front end  99   a  of the main body part  99  of the outer part  98  in the flatly-deployed state of the wrapping material  97 , and is configured to cover the lower of the slits  107  below (between the main body part  99  of the outer part  98  and the folding completion body  130 ) the main body part  99  of the outer part  98  in the state where the wrapping material  97  is wrapped around the folding completion body  130 . Specifically, as shown in  FIGS. 2 and 15 , upon the mounting to the vehicle, the inner part  112  is configured to cover a region from the front side to the rear side of the folding completion body  130  via the upper side, and is configured so that a terminal  112   a  (a front edge in the flatly-deployed state), which is an edge side distant from the region configuring the outer part  98 , is located below a central line CL extending substantially in a horizontal direction from a sectional center C of the folding completion body  130  upon the mounting to the vehicle. 
     The attachment brackets  120  for attaching the respective attachment piece parts  75  to the bottom wall part  21  of the case  20  have a substantially rectangular plate-shaped attachment plate  121  and the attachment bolts  122  protruding downward from the attachment plate  121 , respectively. As shown with the dashed-two dotted line in  FIG. 8 , the attachment plate  121  has a substantially rectangular outer shape of which a width in the right and left direction is larger, and is configured to cover a lower surface-side over a substantially entire region thereof by the attachment piece main body  76  upon attachment to the attachment piece part  75 . The attachment bracket  120  is configured to attach the attachment piece part  75  to the bottom wall part  21  of the case  20  by enabling the attachment bolts  122  protruding from the attachment piece main body  76  of the attachment piece part  75  to protrude from the wrapping material  97  and from the bottom wall part  21  of the case  20  and fixing the attachment bolts with the nuts  124  (refer to  FIGS. 15 and 16 ). Specifically, in the illustrative embodiment, the respective attachment piece parts  75  are attached to the regions of the left portion  21 L and right portion  21 R of the bottom wall part  21 . 
     Subsequently, a process of mounting the airbag device of the illustrative embodiment to the vehicle is described. The inflator  35  is inserted in advance in the inner tube  82  with the attachment bolts  44  protruding from the insertion holes  84  in a state where the inflator main body  36  is held to the attachment bracket  40  by using the clamps  45 . Then, the airbag  50  is folded so as to be accommodated in the case  20 . Specifically, although not shown in detail, in the flatly-deployed state of the airbag  50  with the vehicle body-side wall part  51   a  and the pedestrian-side wall part  51   b  overlapping with each other, the left and right edge portions, which are located at the outermore sides than the attachment piece parts  75  in the right and left direction, are accordion folded to reduce the width dimension in the right and left direction, and the folded airbag reduced in the right and left direction is roll-folded to wrap the vehicle body-side wall part  51   a  from the rear edge, so that the folding completion body  130  having a substantial rod shape extending in the right and left direction is formed (refer to  FIG. 13A ). The folding completion body  130  is wrapped by a rupturable tape material (not shown) for folding collapse prevention at predetermined places except the region adjacent to the opening part  55  for insertion and the region of the attachment piece parts  75 . Then, the cover panel  59  of the opening part  55  for insertion is opened, the inner tube  82  having the inflator  35  inserted therein is inserted into the bag main body  51  via the slit  56  for insertion, the respective attachment bolts  44  are arranged to protrude from the insertion holes  57  and the inflator  35  is accommodated in the bag main body  51 . Then, the cover panel  59  is closed to cover the slit  56  for insertion, and the respective attachment bolts  44  are inserted into the attachment holes  61 . Also, the attachment bolts  122  are arranged to protrude from the through-holes  77 , so that the attachment brackets  120  are attached to the attachment piece parts  75 . 
     Then, the wrapping material  97  is wrapped around the folding completion body  130 . First, as shown in  FIG. 13A , the folding completion body  130  is put at the front end  99   a -side of the outer part  98  of the wrapping material  97  in the flatly-deployed state, the attachment bolts  44  of the inflator  35  are arranged to protrude from the insertion holes  101 F and the attachment bolts  122  of the attachment brackets  120  are arranged to protrude from the insertion holes  102 F. Then, the inner part  112  is wrapped around the folding completion body  130  so as to cover the region from the front surface to the rear surface of the folding completion body  130  via the upper surface with the terminal  112   a  facing rearward (refer to  FIG. 13B ). Then, the outer part  98  is wrapped around the folding completion body  130  so as to cover the inner part  112 , the attachment bolts  44  of the inflator  35  are arranged to protrude from the insertion holes  101 R formed at the rear end  99   b -side and the attachment bolts  122  of the attachment bracket  120  are arranged to protrude from the insertion holes  102 R (refer to  FIG. 14A ). Thereafter, when the respective attachment piece parts  110  are arranged to cover both the left and right ends of the folding completion body  130  while the attachment bolts  122  are arranged to protrude from the insertion holes  110   a , the operation of wrapping the wrapping material  97  around the folding completion body  130  is completed, so that an airbag assembly can be manufactured, as shown in  FIG. 14B . 
     Thereafter, when the airbag assembly is accommodated in the case  20  with the respective attachment bolts  44 ,  122  protruding from the bottom wall part  21  and the nuts  47 ,  124  are fastened to the respective attachment bolts  44 ,  122  protruding from the bottom wall part  21 , the airbag  50  and the inflator  35  can be attached to the case  20 . Then, when the airbag cover  30  is attached to the case  20 , the case  20  is attached to the cowl panel  7   a  by using a bracket (not shown) and the inflator main body  36  is connected to the activation circuit (not shown), the airbag device M can be mounted to the vehicle V. 
     In the airbag device M of the illustrative embodiment, when the activation circuit (not shown) detects a collision between the vehicle V and a pedestrian, based on a signal from the sensor (not shown) arranged at the front bumper  5 , the inflator  35  is activated to enable the inflation gas to flow into the airbag  50 , so that the airbag  50  inflates. The airbag  50  being inflating ruptures the peripheral edge region of the slits  107  of the wrapping material  97  to separate the outer part  98  in the front and rear direction, to bounce the inner part  112  so that the terminal  112   a  is to face forward and to push and open the door part  31  of the airbag cover  30 , and protrudes upward from the opening  20   a  for protrusion of the case  20 , which is formed as the door part  31  is pushed and opened, and covers the region from the upper surface of the rear end  15   c  of the hood panel  15  to the front surface-side of the lower part  4   a  of the front windshield  4  and the lower parts  5   a -side of the front surfaces of the front pillars  5 L,  5 R via the upper surface of the cowl  7 , thereby completing the inflation (refer to the dashed-two dotted line in  FIG. 1 ). 
     In the airbag device M of the illustrative embodiment, the wrapping material  97  wrapped around the folding completion body  130  has the configuration where the slits  107  for rupturing the peripheral edges thereof upon the deployment and inflation of the airbag  50  are arranged in the region covering the upper of the folding completion body  130 . However, since the wrapping material  97  has the inner part  112  so as to cover the lower of the slits  107 , even when the rainwater W and the like are introduced into the wrapping material  97  from the slits  107 , the rainwater W is suppressed from being further introduced into the folding completion body  130  by the inner part  112  and flows along the inner part  112  (refer to  FIG. 15 ). Since the inner part  112  is configured so that the terminal  112   a  is located below the central line CL extending substantially along the horizontal plane from the sectional center C of the folding completion body  130 , it is possible to correctly drop the rainwater W flowing along the inner part  112  from the terminal  112   a  so that the rainwater W is to drop from the folding completion body  130  without being directed toward the folding completion body  130 , thereby causing the rainwater W to be collected at a part, which covers the lower surface-side of the folding completion body  130 , of the wrapping material  97  or to flow along the part, which covers the lower surface-side of the folding completion body  130 , and to be discharged to the outside. For this reason, in the airbag device M of the illustrative embodiment, even when the rainwater W and the like are introduced via the slits  107 , it is possible to correctly prevent the rainwater W from flowing toward the folding completion body  130 . Also, upon the deployment and inflation of the airbag  50 , the peripheral edge portions of the slits  107  are ruptured, so that it is possible to rapidly deploy the airbag  50 . 
     Therefore, according to the airbag device M of the illustrative embodiment, it is possible to rapidly deploy the airbag  50  and to correctly suppress the rainwater W from being introduced into the folding completion body  130 . 
     Also, in the airbag device M of the illustrative embodiment, the openings  104  for exposing the outer peripheral surface of the folding completion body  130  are formed in the region (the region of the front end  99   a -side) extending from the outer part  98 , which covers the lower side of the folding completion body  130 , of the wrapping material  97 . Therefore, it is possible to securely discharge the rainwater W dropped from the terminal  112   a  of the inner part  112  from the openings  104  to the outside. Specifically, in the airbag device M of the illustrative embodiment, the region, which covers the lower side of the folding completion body  130 , of the wrapping material  97  has the double structure of the region of the front end  9   a -side and the region of the rear end  99   b -side. However, in the central region in which the inflator  35  is arranged, the openings  104  are respectively formed at the position between the attachment bolts  44  for attaching the inflator  35  to the bottom wall part  21  and the cutout portions  105  are formed at the positions corresponding to the openings  104  in the region of the rear end  99   b -side of the outer part  98  covering the outer side (lower side) of the openings  104  (refer to  FIG. 14B ). For this reason, even when the rainwater W is introduced into the central region in which the inflator  35  is arranged, it is possible to immediately discharge the rainwater W dropped from the terminal  112   a  from the openings  104  and the cutout portions (openings)  105  to the outside of the wrapping material  97 . Also, in the airbag device M of the illustrative embodiment, the bottom wall part  21  of the case  20  configured to accommodate therein the folding completion body  130  is slightly inclined rearward and downward and the bottom wall part  21  is formed with the discharge holes  23  having a long hole shape in the rear region of the center in the front and rear direction. For this reason, the rainwater W discharged from the wrapping material  97  onto the central portion  21 C of the bottom wall part  21  flows along the bottom wall part  21  and can be immediately discharged from the discharge holes  23  to the outside of the case  20  (refer to  FIG. 15 ). The outer side (the lower) of the openings  104  of the wrapping material  97  formed in the regions of both the left and right ends is covered by the region of the rear end  99   b -side of the outer part  98 . Therefore, when the rainwater W is introduced therein, the rainwater W dropped from the terminal  112   a  of the inner part  112  flows on the region of the rear end  99   b -side of the outer part  98  via the openings  104 . In the airbag device M of the illustrative embodiment, the left portion  21 L and the right portion  21 R of the bottom wall part  21  of the case  20  are inclined downward toward the left and right outer sides. Therefore, the rainwater W flows along the region of the rear end  99   b -side of the outer part  98  due to the inclination and can be discharged from the left edge  99   c -side or right edge  99   d -side of the outer part  98  to the outside of the wrapping material  97  (refer to  FIG. 16 ). Also, the left portion  21 L and the right portion  21 R of the bottom wall part  21  are also slightly inclined rearward and downward and are respectively formed with the discharge holes  23  having a long hole shape in the rear region of the center in the front and rear direction. Therefore, the rainwater W discharged onto the left portion  21 L and the right portion  21 R also flows along the left portion  21 L and the right portion  21 R and can be immediately discharged from the discharge holes  23  to the outside of the case  20 . 
     That is, in the airbag device M of the illustrative embodiment, even when the rainwater W is introduced into the wrapping material  97  via the slits  107 , it is possible extremely suppress the rainwater W from flowing toward the folding completion body  130  and to rapidly discharge the rainwater W to the outside. Therefore, even when the airbag  50  is manufactured by a sewing operation using a sewing thread and is folded so that a seam is exposed to the outer surface-side of the folding completion body  130 , it is possible to correctly prevent the rainwater from being introduced into a region of the seam. 
     Also, as the wrapping material  97  wrapped around the folding completion body  130 , a wrapping material  135  having a configuration shown in  FIGS. 17 and 18  may also be used. Like the wrapping material  97 , the wrapping material  135  has a substantially rectangular outer shape in a flatly-deployed state and has a width dimension in the longitudinal direction, which substantially the same as the length dimension of the folding completion body  130 , and a double structure of an inner part  136  to be arranged at an inner side and an outer part  142  configured to cover an outer side of the inner part  136  in a state where the wrapping material is wrapped around the folding completion body  130 . The outer part  142  and the inner part  136  have the same width dimension in the longitudinal direction (the width dimension of the folding completion body  130  in the axial direction) and are configured to continue in the width direction. 
     The inner part  136  has a main body part  137  configured to cover the outer periphery-side of the folding completion body  130  over the entire circumference, and attachment piece parts  141  protruding from edge portions (a the left edge  137   c  and a right edge  137   d ) of the main body part  137  in the longitudinal direction. Each attachment piece part  141  is formed at a substantial central position of the main body part  137  in the width direction (the front and rear direction in the flatly-deployed state), and two insertion holes  145   a  for inserting therein the attachment bolts  122  are arranged at a tip end thereof. Both ends (a front end  137   a  and a rear end  137   b  in the flatly-deployed state) of the main body part  137  in the width direction are formed with insertion holes  138 F,  138 R,  139 F,  139 R for inserting therein the respective attachment bolts  44 ,  122 . The insertion holes  138 F,  138 R are respectively formed in a central region of the inner part  136  in the right and left direction three by three, in correspondence to the attachment bolts  44 , and the insertion holes  139 F,  139 R are respectively formed at both left and right ends of the inner part  136  two by two, in correspondence to the attachment bolts  122 . 
     Slits  140  are intermittently formed at a substantial central position of the inner part  136  in the width direction, substantially along the longitudinal direction (the axial direction of the folding completion body  130 ). Like the slits  107  of the wrapping material  97 , the slits  140  are formed to have intervals (coupling portions) therebetween by intermittently making linear cut lines at the inner part  136 , and are arranged at an upper position (the opening  20   a  for protrusion of the case  20 ) of the folding completion body  130  in the state where the inner part  136  is accommodated with being wrapped around the folding completion body  130  in the case  20  (refer to  FIG. 17 ). The slits  140  are ruptured at peripheral edge portions (the portions between the slits  140 ; the coupling portions) upon the inflation of the airbag  50 . Like the slits  107  of the wrapping material  97 , the slits  140  are configured so that end portions are located in the regions of the attachment piece parts  141  beyond the main body part  137 . 
     The outer part  142  is arranged to extend forward continuously from the front end  136   a  of the inner part  136  in the flatly-deployed state of the wrapping material  135 . In the illustrative embodiment, the outer part  142  has a main body part  143  formed continuously from the inner part  136  and temporary joining piece portions  147  protruding from a terminal  143   a  (a front edge in the flatly-deployed state) in the width direction, which is distant from the inner part  136  of the main body part  143 . The main body part  143  is configured to cover the upper of the slits  140  at the outer periphery-side of the inner part  136  and to wrap a region beyond the slits  140  in the state where the wrapping material  135  is wrapped around the folding completion body  130 . Specifically, as shown in  FIG. 17 , the main body part  143  is configured to cover a region from the front side to the rear side of the folding completion body  130  via the upper side at the outer periphery-side of the inner part  136  and is configured so that the terminal  112   a  (a front edge in the flatly-deployed state), which is an edge side distant from the region configuring the inner part  136 , is located at a rear lower position of the folding completion body  130  when mounted to the vehicle. 
     In the illustrative embodiment, the temporary joining piece portions  147  have a band shape protruding from the terminal  143   a  of the main body part  143  and extending in the front and rear direction in the flatly-deployed state of the wrapping material  135 , respectively, and the three temporary joining piece portions are formed in correspondence to the attachment bolts  44  of the inflator  35 . Each temporary joining piece portion  147  is formed at a tip end  147   a  with an insertion hole  148  for inserting the attachment bolt  44 . Also, a base part  147   b  of each temporary joining piece portion  147  is provided with a slit  149 , which is formed by making a linear cut line. The slit  149  is configured to separate the main body part  143  and the temporary joining piece portion  147  by rupturing the peripheral edge upon the deployment and inflation of the airbag  50 . That is, the temporary joining piece portion  147  is configured to temporarily join the terminal  143   a  of the main body part  143  of the outer part  142 , which is an edge side distant from the region configuring the inner part  136 , to the side of the folding completion body  130  by inserting the attachment bolt  44  into the insertion hole  148 , and the slit  149  formed at the base part  147   b -side is ruptured upon the deployment and inflation of the airbag  50 , such that the joined state to the folding completion body  130  is released. 
     Although not shown in detail, a process of wrapping the wrapping material  135  around the folding completion body  130  is described. First, in the flatly-deployed state of the wrapping material  135 , the folding completion body  130  is put at the rear end  137   b -side of the main body part  137  of the inner part  136 , the attachment bolts  44  of the inflator  35  are arranged to protrude from the insertion holes  138 R and the attachment bolts  122  of the attachment bracket  120  are arranged to protrude from the insertion holes  139 R. Then, the main body part  137  of the inner part  136  is wrapped around the folding completion body  130 , the attachment bolts  44  are arranged to protrude from the insertion holes  138 F, and the attachment bolts  122  are arranged to protrude from the insertion holes  139 F. Thereafter, the attachment piece parts  141  are arranged to cover both the left and right ends of the folding completion body  130  with the attachment bolts  122  protruding from the insertion holes  141   a . Then, the main body part  143  of the outer part  142  is wrapped around the folding completion body  130  so as to cover the outer periphery-side of the inner part  136 , and the respective temporary joining piece portions  147  are temporarily joined to the terminal  143   a  of the main body part  143  by inserting the attachment bolts  44  into the insertion holes  148  formed at the tip end  147   a , so that the operation of wrapping the wrapping material  135  around the folding completion body  130  is completed. 
     Also in the airbag device in which the wrapping material  135  configured as described above is used, the slits  140  formed in the region covering the upper of the folding completion body  130  are formed at the inner part  136 , and the outer periphery-side of the inner part  136  is wrapped up to the region beyond the slits  140  by the outer part  142 , so that it is possible to securely prevent the rainwater from being introduced to the folding completion body  130  through the slits  140 . 
     Therefore, also in the airbag device in which the wrapping material  135  configured as described above is used, it is possible to rapidly deploy the airbag  50  and to correctly suppress the rainwater from being introduced into the folding completion body  130 . 
     Also, according to the wrapping material  135  configured as described above, the outer part  142  (the main body part  143 ) has the configuration where the terminal  143   a  of the edge side distant from the region configuring the inner part  136  of the wrapping material  135  is temporarily joined to the side of the folding completion body  130  such that the joined state to the folding completion body  130  can be released upon the rupture of the slit  140 . For this reason, it is possible to securely wrap the outer periphery-side of the inner part  136  having the slits  140  by the outer part  142 . Also, even in the configuration where the outer periphery-side of the inner part  136  is wrapped by the outer part  142 , since the joined state of the terminal  143   a  to the side of the folding completion body  130  is also released upon the rupture of the slits  140  at the early stage of the inflation of the airbag  50 , it is possible to rapidly deploy the airbag  50  upon the deployment and inflation of the airbag  50 , without interference with the rapid deployment and inflation of the airbag  50 . On the other hand, when the above points are not considered, the outer part may be simply arranged to wrap the outer periphery-side of the inner part up to the region beyond the slits, without temporarily joining the terminal of the outer part to the side of the folding completion body. 
     In the illustrative embodiment, as the means for temporarily joining the terminal  143   a  of the main body part  143  of the outer part  142  to the side of the folding completion body  130 , the temporary joining piece portion  147  configured integrally with the main body part  143  and having the rupturable slit  149  arranged at the base part  147   b -side, which is the main body part  143 -side, is used. However, the temporary joining means is not limited thereto. For example, a configuration where a terminal is bonded to an inner member-side by using a separate tape material capable of rupturing or releasing a bonded state to release a joined state upon the deployment and inflation of the airbag is also possible. 
     Also, in the illustrative embodiment, the main body part  143  of the outer part  142  is configured so that the terminal  143   a  is arranged in the region of the rear lower end-side of the folding completion body  130  upon the mounting to the vehicle. However, the main body part may have the smaller width dimension in the width direction inasmuch as it can wrap even the region beyond the slit. 
     In the illustrative embodiment, as the airbag device that is to be arranged at the outer side of the vehicle interior, the airbag device M for pedestrian that is mounted in the vicinity of the rear end  15   c  of the hood panel  15  has been exemplified. However, the airbag device to which the present invention can be applied is not limited to the illustrative embodiment. For example, the present invention can be applied to an airbag device that is to be accommodated in a front grill at the front of the hood panel or left and right side fender parts of the hood panel, too. 
     According to an aspect of the invention, there is provided an airbag device comprising: an airbag accommodated with being folded in an accommodation part to be arranged at an outer side of a vehicle interior and configured to protrude toward an outside of a vehicle upon inflation, the airbag accommodated in the accommodation part in a state where a wrapping material formed of a flexible sheet body is wrapped around a folding completion body formed by folding the air bag, wherein the accommodation part has an opening for protrusion at an upper side so as to enable the airbag to protrude therefrom, wherein the wrapping material is wrapped over an entire circumference around the folding completion body and a region thereof configured to cover an upper of the folding completion body has a double structure of an outer part and an inner part, wherein the outer part has slits that are intermittently formed substantially along an axial direction of the folding completion body so that peripheral edges thereof can be ruptured upon deployment and inflation of the airbag, and wherein the inner part is configured to cover a lower of the slits and is configured so that a terminal, which is an edge side distant from a region configuring the outer part of the wrapping material, is located below a central line extending substantially in a horizontal direction from a sectional center of the folding completion body. 
     In the airbag device of the present invention, the wrapping material wrapped around the folding completion body has the configuration where the slits for rupturing the peripheral edges thereof upon the deployment and inflation of the airbag are arranged in the region covering the upper of the folding completion body. However, since the wrapping material has the inner part so as to cover the lower of the slits, even when the rainwater and the like are introduced into the wrapping material from the slits, the rainwater is suppressed from being further introduced into the folding completion body by the inner part and flows along the inner part. Since the inner part is configured so that the terminal, which is the edge side distant from the region configuring the outer part of the wrapping material, is located below the central line extending substantially along the horizontal plane from the sectional center of the folding completion body, it is possible to correctly drop the rainwater flowing along the inner part from the terminal so that the rainwater is to drop from the folding completion body without being directed toward the folding completion body, thereby causing the rainwater to be collected at a part, which covers the lower surface-side of the folding completion body, of the wrapping material or to flow along the part, which covers the lower surface-side of the folding completion body, and to be discharged to an outside. For this reason, in the airbag device of the present invention, even when the rainwater and the like are introduced via the slits, it is possible to correctly prevent the rainwater from flowing toward the folding completion body. Also, upon the deployment and inflation of the airbag, the peripheral edge portions of the slits are ruptured, so that it is possible to rapidly deploy the airbag. 
     Therefore, according to the airbag device of the present invention, it is possible to rapidly deploy the airbag and to correctly suppress the rainwater from being introduced into the folding completion body. 
     Also, in the airbag device of the present invention, a region, which extends from the outer part so as to cover a lower side of the folding completion body, is preferably formed with an opening for exposing an outer peripheral surface of the folding completion body because it is possible to securely discharge the rainwater dropped from the terminal of the inner part from the opening to the outside. 
     Also, in an airbag device, the wrapping material may be wrapped over an entire circumference around the folding completion body and a region thereof configured to cover the upper of the folding completion body may have a double structure of an outer part and an inner part, slits that are intermittently formed substantially along an axial direction of the folding completion body so that peripheral edges thereof can be ruptured upon deployment and inflation of the airbag may be arranged in a region, which covers the upper of the folding completion body, of the inner part, and the outer part may be arranged to cover even a region beyond the slits. 
     In the airbag device configured as described above, the slits formed in the region covering the upper of the folding completion body are formed at the inner part, and the outer periphery-side of the inner part is wrapped up to the region beyond the slits by the outer part, so that it is possible to securely prevent the rainwater from being introduced to the folding completion body via the slits. 
     Therefore, also in the airbag device configured as described above, it is possible to rapidly deploy the airbag and to correctly suppress the rainwater from being introduced to the folding completion body. 
     Also, in the airbag device configured as described above, the outer part is preferably configured so that a terminal, which is an edge side distant from a region configuring the inner part of the wrapping material, is temporarily joined to a side of the folding completion body such that a joined state to the folding completion body can be released upon rupture of the slits. That is, thereby, it is possible to securely wrap the outer periphery-side of the inner part having the slits by the outer part. Also, even in the configuration where the outer periphery-side of the inner part is wrapped by the outer part, since the joined state of the terminal to the side of the folding completion body is also released upon the rupture of the slits at the early stage of the inflation of the airbag, it is possible to rapidly deploy the airbag upon the deployment and inflation of the airbag, without interference with the rapid deployment and inflation of the airbag.