Abstract:
In a pedestrian protection airbag system, an airbag module extending in the lateral direction of a vehicle body is disposed between a rear edge of a hood and a front edge of a cowl top, thereby mounting the airbag module without affecting the intake of air into a vehicle compartment or the positioning of wipers; and the left and right ends of the airbag module are supported by upper parts of left and right front wheel damper housings, whereby the damper housings obtain a high rigidity to reliably bear a reaction force during deployment of an airbag without particularly enhancing the rigidity of the cowl top. Thus, it is possible to rigidly support the airbag module in the pedestrian protection airbag system while minimizing the influence on the shape or structure of the cowl top.

Description:
RELATED APPLICATION DATA  
       [0001]     The Japanese priority application No. 2004-246187 upon which the present application is based is hereby incorporated in its entirety herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a pedestrian protection airbag system comprising an airbag and an inflator that generates gas to deploy the airbag along an upper face of a cowl top and a front face of a windshield upon contact with a pedestrian.  
         [0004]     2. Description of the Related Art  
         [0005]     Japanese Patent Application Laid-open No. 2003-252140 discloses a pedestrian protection airbag system comprising an airbag module which is disposed within a cowl top positioned between a rear edge of a hood and a front edge of a windshield of an automobile; and when the automobile hits a pedestrian, the airbag is deployed from the cowl top so as to protect the pedestrian.  
         [0006]     However, in this conventional arrangement, since the airbag module is disposed within the cowl top, the airbag module disadvantageously impedes air being taken into a vehicle compartment through the cowl top and restricts the degree of freedom in a wiper layout or a cowl top shape. Further, since the airbag module receives a downward reaction load when the airbag is deployed, it is necessary to enhance the rigidity of the cowl top which supports the airbag module and the rigidity of a dashboard which is connected to the cowl top, disadvantageously leading to an increase in the vehicle body weight.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention has been accomplished under the above-mentioned circumstances, and it is an object thereof to rigidly support an airbag module in a pedestrian protection airbag system while minimizing the influence on the shape or structure of a cowl top.  
         [0008]     In order to achieve the above-mentioned object, according to a first feature of the invention, there is provided a pedestrian protection airbag system comprising: an airbag module disposed along a front face of a cowl top so as to extend in the lateral direction of a vehicle body, with its left and right ends supported on upper parts of left and right damper housings of left and right front wheels, the airbag module comprising: an airbag; and an inflator that generates gas to deploy the airbag along an upper face of the cowl top and a front face of a windshield upon contact with a pedestrian.  
         [0009]     According to a second feature of the present invention, in addition to the first feature, the upper parts of the left and right damper housings are connected to each other by a reinforcing member that functions as a retainer for housing the inflator and the airbag of the airbag module.  
         [0010]     According to a third feature of the present invention, in addition to the first feature, the airbag module comprises a cover that opens when the airbag is deployed, the cover being divided into a plurality of lids arranged in the lateral direction of the vehicle body by means of laser-processed breakable brittle portions.  
         [0011]     A strut tower bar of an embodiment corresponds to the reinforcing member of the present invention.  
         [0012]     With the first feature, since the airbag module, which extends in the lateral direction of the vehicle body, is disposed along the front face of the cowl top, it is possible to mount the airbag module without affecting the intake of air into a vehicle compartment or the positioning of wipers. Further, since the left and right ends of the airbag module are supported by the upper parts of the left and right damper housings of the left and right front wheels, the damper housings obtain a high rigidity to reliably bear the reaction force during deployment of the airbag, without particularly enhancing the rigidity of the cowl top.  
         [0013]     With the second feature, since the reinforcing member, which provides a connection between the upper parts of the left and right damper housings, functions as the retainer for housing the inflator and the airbag of the airbag module, it is possible to ensure the rigidity of the vehicle body by means of the reinforcing member while reducing the strength required for the airbag module by making the reinforcing member support the reaction load during deployment of the airbag.  
         [0014]     With the third feature, since the cover of the airbag module is divided into the plurality of lids arranged in the lateral direction of the vehicle body by means of the brittle portions, the cover can be opened smoothly by splitting it into the plurality of lids when deploying the airbag. Further, the brittle portions are laser-processed to be inconspicuous, thus improving the appearance.  
         [0015]     The above-mentioned object, other objects, characteristics, and advantages of the present invention will become apparent from an explanation of preferred embodiments that will be described in detail below by reference to the attached drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a plan view of a front part of a vehicle body of an automobile mounting a pedestrian protection airbag system according to a first embodiment of the present invention.  
         [0017]      FIG. 2  is an enlarged sectional view along line  2 - 2  in  FIG. 1 .  
         [0018]      FIG. 3  is a view from arrow  3  in  FIG. 1 .  
         [0019]      FIG. 4  is an exploded perspective view of an airbag module.  
         [0020]      FIG. 5  is an enlarged sectional view along line  5 - 5  in  FIG. 3 .  
         [0021]      FIG. 6  is an enlarged sectional view along line  6 - 6  in  FIG. 2 .  
         [0022]      FIG. 7  is a diagram corresponding to  FIG. 2 , for explaining the operation when the airbag is deployed.  
         [0023]      FIG. 8  is a diagram corresponding to  FIG. 2 , of a second embodiment.  
         [0024]      FIG. 9  is an exploded perspective view of a cover and a hinge member.  
         [0025]      FIG. 10  is a diagram corresponding to  FIG. 2 , of a third embodiment.  
         [0026]      FIG. 11  is a diagram corresponding to  FIG. 1 , of a fourth embodiment. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0027]     As shown in  FIG. 1 , an airbag module  13  extending in the lateral direction of a vehicle body is disposed between a rear edge of a hood  11  and a front edge of a cowl top  12  of an automobile. When a pedestrian is hit by a front part of the vehicle body, an airbag  14  is deployed from the airbag module  13  to a position shown by the chain line so as to cover an upper face of the cowl top  12 , a front face of a lower part of a windshield  15 , and front faces of lower parts of left and right front pillars  16 , thus protecting the head of the pedestrian who has been bounced up onto the hood  11 .  
         [0028]     As is clear from  FIG. 2 , the cowl top  12  is formed into a duct-like shape extending in the lateral direction of the vehicle body by comprising a cowl top outer part  17 , a cowl top inner part  18  and a cowl top grill  19 . The front end of a dash panel inner part  20  is connected to a portion joining together the cowl top outer part  17  and the cowl top inner part  18 . The front end of a dash panel outer part  21  and the front end of the windshield  15  are connected to a portion joining together the cowl top inner part  18  and the cowl top grill  19 . The upper face of the dash panel outer part  21  is covered by an instrument panel  22 .  
         [0029]     As is clear from  FIG. 2  to  FIG. 4 , the airbag module  13  includes: a container-shaped retainer  23  having an open top face; an inflator  24  disposed in a central lower part of the retainer  23 ; an airbag  14  housed within the retainer  23  in a folded state; and a cover  25  made of a synthetic resin such as polypropylene covering the open top face of the retainer  23 . The cover  25  has an open lower face whose edge is fitted to the periphery of the retainer  23 , and secured to the retainer  23  by means of rivets  27  running through a metal band  26  wound around the cover  25 .  
         [0030]     The cover  25  includes an upper wall  25   a , a front wall  25   b  and a rear wall  25   c . The upper wall  25   a  is connected flush to the rear edge of the hood  11 , and curved in an arc shape so that a central part in the lateral direction of the upper wall  25   a  projects toward the front of the vehicle body. A hinge part  25   d  is formed to be a thin-walled part extending along the border between the upper wall  25   a  and the front wall  25   b  of the cover  25  in the lateral direction of the vehicle body. A brittle portion  25   e  is formed by perforations extending in the lateral direction of the vehicle body in the vicinity of the upper end of the rear wall  25   c , by laser processing the reverse face side of the cover  25 . A plurality of brittle portions  25   f  are formed by perforations extending in the longitudinal direction of the vehicle body, by laser processing the reverse face of the upper wall  25   a . The brittle portion  25   e  and brittle portions  25   f  are arranged in a comb shape, that is, forward ends of the brittle portions  25   f  are connected to the hinge part  25   d , thereby dividing the upper wall  25   a  of the cover into a plurality of strip-shaped lids  28 .  
         [0031]     As is clear from  FIG. 3  and  FIG. 5 , a damper housing  30  housing a suspension damper (not illustrated) projects from a rear part of each of left and right front wheelhouses  29  provided within an engine compartment. A bracket  31  is welded to a side face of an upper part of each of the damper housings  30 . A bracket  34  welded to the vicinity of an end part of the retainer  23  of the airbag module  13  is secured by bolts  35  to the upper end of a coupling member  33  which is secured by bolts  32  to the bracket  31 .  
         [0032]     The operation of the first embodiment of the present invention having the above-mentioned arrangement is now described.  
         [0033]     When the impact of a pedestrian being hit by the vehicle is detected, the inflator  24  generates gas to inflate the folded airbag  14 , and the resultant pressure acts on the reverse face of the upper wall  25   a  of the cover  25 . Since the comb-shaped brittle portions  25   e  and  25   f  are formed in the synthetic resin cover  25 , the brittle portions  25   e  and  25   f  are ruptured by the pressure of the airbag  14 , so that the plurality of lids  28  which are divided into strips open forward with the hinge part  25   d  at the front end serving as a fulcrum, thereby deploying the airbag  14  through the resultant opening. As shown in  FIG. 1  and  FIG. 7 , the deployed airbag  14  covers the upper face of the cowl top  12 , the front face of the windshield  15 , and the front faces of the front pillars  16 , thereby protecting the pedestrian who has been bounced up onto the hood  11 .  
         [0034]     Since the airbag module  13  is disposed along the front face of the cowl top  12  as described above without being housed within the cowl top  12 , the airbag module  13  does not affect the intake of air into the vehicle compartment and the wiper positioning. Further, since the left and right ends of the airbag module  13  are supported by the upper parts of the left and right front wheel damper housings  30 , the damper housings  30  obtain a high rigidity to reliably bear the reaction force during deployment of the airbag  14  without particularly enhancing the rigidity of the cowl top  12 , the dash panel inner part  20 , the dash panel outer part  21  and the other parts. Furthermore, the airbag module  13  having the above-described structure reinforces the vehicle body to enhance the rigidity.  
         [0035]     In this embodiment, if the upper wall  25   a  was a single body, it could not pivot smoothly around the hinge part  25   d , because the hinge part  25   d  at the front edge of the cover  25  is curved in the arc shape. However, since the upper wall  25   a  is divided into the strip-shaped lids  28  by the brittle portions  25   e  and  25   f , the lids  28  can smoothly pivot as shown in  FIG. 6 . Further, since the brittle portions  25   e  and  25   f  are laser-processed to be perforations, they become inconspicuous to improve the appearance.  
         [0036]     A second embodiment of the present invention is now described by reference to  FIG. 8  and  FIG. 9 .  
         [0037]     In the above-described first embodiment, the hinge part  25   d  is formed integrally with the synthetic resin cover  25 , providing a possibility that the hinge part  25   d  might become brittle to split at low temperature. In the second embodiment, a cover  25  includes an iron hinge member  41  in place of a front wall  25   b  and a hinge part  25   d . The hinge member  41  includes: a front wall  41   a  secured by rivets  27  to a retainer  23 ; and upper wall strips  41   b  which are formed by splitting an upper wall and secured by hot upsetting to lower faces of a plurality of lids  28 .  
         [0038]     In accordance with the second embodiment, since the iron hinge member  41  functions as a fulcrum when the upper wall  25   a  of the cover  25  opens while splitting into the plurality of lids  28 , the hinge member  41  does not break to fly asunder even at low temperature. The other components and operational effects of the second embodiment are the same as those of the first embodiment.  
         [0039]     A third embodiment of the present invention is now described by reference to  FIG. 10 .  
         [0040]     In the cover  25  of the second embodiment, the upper wall  25   a  and the rear wall  25   c  are integral components; however, in a cover  25  of the third embodiment, a rear wall  25   c  is formed from a member that is separate from an upper wall  25   a , and is secured to the upper wall  25   a  by hot upsetting.  
         [0041]     In accordance with the third embodiment, forming the upper wall  25   a  and the rear wall  25   c  as separate members enables the cover  25  to be easily molded. The other components and operational effects of the third embodiment are the same as those of the second embodiment.  
         [0042]     A fourth embodiment of the present invention is now described by reference to  FIG. 11 .  
         [0043]     In the fourth embodiment, upper ends of left and right damper housings  30  are connected by a strut tower bar  51  which is a metal reinforcing member, thus enhancing the rigidity of a vehicle body. Since the load generated by an airbag  14  being deployed can be supported by the strut tower bar  51 , an airbag module  13  includes a synthetic resin casing  52  in place of the metal retainer  23 , and this casing  52  is fixed to an upper face of the strut tower bar  51  by means of bolts  53  and nuts  54 .  
         [0044]     In accordance with the fourth embodiment, since the strut tower bar  51  which provides a connection between the upper ends of the left and right damper housings  30  functions as a retainer  23  for the airbag module  13 , the retainer  23  can be eliminated while enhancing the rigidity of the vehicle body by the strut tower bar  51 , thereby reducing the cost of the airbag module  13 . The other components and operational effects of the fourth embodiment are the same as those of the first embodiment.  
         [0045]     Although embodiments of the present invention have been described in detail above, the present invention is not limited to the above-mentioned embodiments and can be modified in a variety of ways without departing from the subject matter of the present invention.