Abstract:
An external airbag system for a vehicle is proved to be commercialized and which can absorb impact induced by a frontal collision of the vehicle and thus substantially protect passengers in the vehicle. The external airbag system may include a bumper cover, a cushion provided behind the bumper cover, and an inflator for generating a gas pressure to deploy the cushion, wherein the bumper cover moves in a forward direction by the deploying cushion.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Korean Patent Application Number 10-2008-0122422, filed on Dec. 4, 2008, the entire contents of which is incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an external airbag which is provided in a front portion of a vehicle and is deployed just before the vehicle collides with an obstacle in front of the vehicle in order to absorb impact. 
     2. Description of Related Art 
     Hitherto, development of airbags for vehicles has focused on airbags (hereinafter, referred to as “internal airbags”) which are installed in passenger compartments of vehicles to reduce a degree to which passengers are injured by collision with vehicle bodies or rigid parts in the passenger compartment. Driver-side airbags, passenger-side airbags, curtain airbags and seat-side airbags are representative examples of such internal airbags. 
     Recently, efforts have been made to reduce the impact to an entire vehicle which results from a collision with obstacles. An external airbag is one such effort. The external airbag is installed in a space between a bumper and a vehicle body. The external airbag is deployed forwards just before the vehicle collides with an obstacle, thus absorbing and mitigating impact. 
     However, to date, there has been taken only a conceptual approach to deploying an external airbag ahead of a bumper using gas pressure generated from an inflator. An external airbag system which can substantially exhibit the performance of protecting passengers has not yet been introduced. 
     The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
     BRIEF SUMMARY OF THE INVENTION 
     Various aspects of the present invention are directed to provide an external airbag system for a vehicle which can be commercialized and which can absorb impact induced by a frontal collision of the vehicle and thus substantially protect passengers in the vehicle. 
     In an aspect of the present invention, the external airbag system for a vehicle, may include a bumper cover, at least a cushion provided behind the bumper cover, and at least an inflator for generating a gas pressure to deploy the cushion, wherein the bumper cover moves in a forward direction by the deploying cushion, wherein a portion of the bumper cover is fixed to a back beam. 
     The back beam may be fixed to a medial portion of the bumper cover and the cushions are disposed behind the bumper cover symmetrically with respect to the medial portion thereof with equal numbers. 
     One of the cushions may be provided to one side of the bumper cover and one of the cushions is provided to the other side of the bumper cover so that each side of the bumper cover is configured to be rotated forwards around the portion that the bumper cover and the back beam are fixed each other by a deployment force of the corresponding cushion, wherein a degree to which a portion of the cushion adjacent to corresponding distal end of the bumper cover is inflated is larger than a degree to which a portion of the cushion adjacent to the portion that the bumper cover and the back beam are fixed each other is inflated. 
     The external airbag system may further include at least a seam line formed on an inner surface of the bumper cover near the fixed portion of the bumper cover and the back beam. 
     The external airbag system may further include a holding member to limit a movement distance of each side of the bumper cover within a predetermined distance while the cushion is deployed. 
     The holding member may be a tether connected to each side of the bumper cover to the back beam. 
     The cushion and the inflator may be installed in a back beam provided behind the bumper cover and a recess is formed in the back beam to contain the cushion and the inflator therein, wherein a support bracket is provided on at least one of an upper surface and/or a lower surface of the back beam to support, along with the back beam, a rear portion of the cushion that is in a deployed state, and wherein the recess has a first recess for containing the cushion therein, and a second recess extending a predetermined depth rearwards from the first recess to contain the inflator therein, 
     The external airbag system, may further include a retainer provided in the recess between the inflator and the back beam to fasten the inflator to the back beam, wherein the cushion is fastened to the retainer. 
     The external airbag system, may further include a retainer ring provided between the cushion and the back beam, the retainer ring having the inflator therein and fastened to the back beam. 
     The external airbag system, may further include a sensing unit for detecting an obstacle in front of the vehicle, and a control unit for determining whether the vehicle collides with the obstacle using a signal transmitted from the sensing unit and, when the collision is anticipated, operating the inflator before the vehicle collides with the obstacle. 
     In another aspect of the present invention, the external airbag system for a vehicle, may include a bumper cover, at least a cushion provided behind the bumper cover, at least an inflator for generating a gas pressure to deploy the cushion, and a back beam provided behind the bumper cover and having therein at least a recess for containing the cushion and the inflator, wherein at least one portion of the bumper cover is moved forwards away from an original position thereof by deployment force of the cushion, wherein a support bracket is provided on at least one of an upper surface and/or a lower surface of the back beam to support, along with the back beam, a rear portion of the cushion that is in a deployed state and a tether is connected between each of opposite sides of the bumper cover and the back beam. 
     The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view illustrating an exemplary external airbag system for a vehicle, according to the present invention. 
         FIG. 2  is a view showing deployment of the external airbag system on the basis of  FIG. 1 . 
         FIG. 3  is a schematic sectional view of the external airbag system of  FIG. 1 . 
         FIG. 4  is an exploded view of the external airbag system shown in  FIG. 3 . 
         FIG. 5  is a view showing deployment of the external airbag system shown in  FIG. 3 . 
         FIG. 6  is a view showing tethers of the external airbag system of  FIG. 2  which are connected between a bumper cover and a back beam. 
         FIG. 7  is a schematic view illustrating an exemplary external airbag system for a vehicle, according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     As shown in  FIG. 1 , an external airbag system according to various embodiments of the present invention includes cushions  20  which are installed in a front portion of the vehicle, a sensing unit which detects an obstacle in front of the vehicle, and a control unit  40  which determines whether the vehicle will collides with the obstacle using a signal transmitted from the sensing unit and, when the collision is anticipated, deploys the cushion  20  before the vehicle collides with the obstacle. A radar sensor  30   a  or/and a camera  30   b  can be used as the sensing unit. In  FIG. 1 , the reference numeral  1  and  2  respectively denote a driver&#39;s seat airbag and a passenger seat airbag. 
     Referring to  FIG. 2 , the cushions  20  are installed in respective recesses  51  which are formed in a back beam  50  behind opposite sides of the bumper cover  10 . The bumper cover  10  can be moved forwards from its original position by deployment force of the cushions  20  and, in detail, the opposite sides of the bumper cover  10  can be respectively rotated forwards around the medial portion thereof. 
     To facilitate this rotational motion of the bumper cover  10 , in various embodiments of the present invention, seam lines  13  which extend in the vertical directions may be formed in the inner surface of the bumper cover  10  at positions corresponding to a boundary with a license plate  4 . When the cushions  20  are completely deployed, a degree to which outer portions of the cushions  20  corresponding to the opposite sides of the bumper cover  10  are inflated is larger than that of inner portions thereof corresponding to the medial portion of the bumper cover  10 . A degree to which the opposite sides of the bumper cover  10  are moved away from the back beam  50  or are opened is determined by the tethers  95  running between the bumper cover  10  and the back beam  50 . The number of the seam lines  13  may be increased so as to prevent a crack that may occur along the seam lines. 
     Meanwhile, the bumper cover  10  includes a bumper skin  11  and an absorber  12 . Front side members  3  are connected to the rear surface of the back beam  50 . 
     Referring to  FIG. 3 , an inflator  60  along with the cushion  20  is installed in each of the recesses  51  of the back beam  50 . The inflator  60  generates gas pressure for deploying the cushion  20 . For this, the recess  51  has a first recess  51   a  which contains the cushion  20  therein, and a second recess  51   b  which extends rearwards from the first recess  51   a  to a predetermined depth to contain the inflator  60  therein. The inflator  60  is disposed outside the cushion  20 . A communication structure for transmission of gas pressure between the inflator  60  and the cushion  20  is provided therebetween. Support brackets  80  are provided on and under the back beam  50  to support the rear portion of the cushion  20  when it is deployed. 
     The structure for fastening the cushion  20  and the inflator  60  to the back beam  50  using a retainer  70  in the recess  51  will be explained with reference to  FIGS. 3 and 4 . 
     The retainer  70  includes a retainer frame  71  which has a mounting hole  71   a  on a central portion thereof, and a flange  72  which is provided along the outer edge of the retainer frame  71 . The retainer  70  is disposed in a front surface of the cushion  20 . The cushion  20  and the retainer  70  are fastened to the back beam  50  using fastening bolts  75  which are tightened from the interior of the cushion  20  into fastening holes  53  of the back beam  50  via through holes  73  of the retainer  70 . The fastening bolts  75  are previously welded or fixed to the retainer  70 . The cushion  20  is fastened to the retainer  70  by the fastening bolts  75 . A nut on the rear surface of the back beam  50  is tightened over each fastening bolt  75 . The fastening holes  53  are formed through a stepped portion  52  which forms a boundary between the first recess  51   a  and the second recess  51   b . The flange  72  guides the direction in which the cushion  20  is deployed, and prevents the cushion  20  from being damaged by the sharp edge of the retainer frame  71 . 
     Furthermore, the inflator  60  which is disposed between the cushion  20  and the back beam  50  is mounted to the rear surface of the retainer  70  using mounting brackets  90 . To reliably mount the inflator  60  to the retainer  70 , semicircular seating portions  71   b  are formed in the retainer  70 . The inflator  60  is mounted to the retainer  70  in such a way as to insert it forwards into the semicircular seating portions  71   b . The inflator  60  is fastened to the retainer  70  using the mounting bracket  90  which is fastened to the retainer  70  by mounting bolts  76  which are tightened into mounting holes  74  of the retainer frame  71  via through holes  91  of the mounting bracket  90 . A connection hole  55  is formed in the second recess  51   b , into which the inflator  60  is seated, so that an external electric wire  61  is connected to the inflator  60  through the connection hole  55 . 
     Meanwhile, as is well-known to those skilled in the art, each cushion  20  is covered with a cover  21  such that it maintains a folded shape. A tear line  22  is horizontally formed in the cover  21  so that when the cushion  20  is inflated, it is extracted from the cover  21  through the tear line  22 . 
     In various embodiments of the present invention, as shown in  FIGS. 4 and 5 , the support brackets  80  are respectively provided on the upper surface of the back beam  50  and under the lower surface thereof at positions corresponding to the recess  51 . Each support bracket  80  includes a mounting part  81  which is fastened to the back beam  50 , and a support part  82  which perpendicularly extends from the mounting part  81 . When the vehicle collides with a preceding vehicle  6 , the cushions  20  withstand impact transmitted from the preceding vehicle  6  and are inflated upwards and downwards. At this time, the support brackets  80  support portions of the corresponding cushion  20  which are other than those portions supported by the back beam  50 , in other words, the support brackets  80  increase the area and force of support for the cushion  20 . 
     As shown in  FIG. 6 , a structure for mounting the tethers  95  is provided on the inner surface of each of the opposite sides of the bumper cover  10 . In detail, brackets  12  are provided on the inner surface of the bumper skin  11 . A holder  13  is provided on each bracket  12 . One end of each tether  95  is fastened to the holder  13  of the corresponding bracket  12 . The holder  13  is rotatable on the bracket  12  around a point at which the holder  13  is coupled to the bracket  12 . In addition, a structure for mounting the tethers  95  is also provided on the back beam  50  to correspond to the above tether mounting structure. When the cushions  20  are completely deployed, the opposite sides of the bumper cover  10  may rattle in the state of being bent forwards. Such rattling of the bumper cover  10  can be prevented by the tethers  95 . 
     Next, an external airbag system for a vehicle according to various embodiments of the present invention will be described with reference to  FIG. 7 . The general construction of the airbag system according to various embodiments, besides the installation structure of the inflator, remains the same. Therefore, further explanation of structures or elements that have been mentioned in the description of the above-described embodiment(s) is deemed unnecessary. 
     Referring to  FIG. 7 , an inflator  60  of the airbag system may be installed in a cushion  20 . The inflator  60  is fastened to a back beam  50  using a retainer ring  100  which is of a ring shape and surrounds the inflator  60 . In detail, the inflator  60 , the cushion  20  and the retainer ring  100  are fastened to the back beam  50  by a coupling unit  110  which is fastened to the back beam  50  via the retainer ring  100  and the cushion  20 . Reference numeral  56  is an insert hole for a nut positioned in the back beam  50 . 
     In various embodiments of the present invention, the numbers of the cushions may be increased. In this case, the cushions may be disposed symmetrically with respect to a medial portion of the bumper cover with equal numbers. 
     As described above, in an external airbag system for a vehicle according to the present invention, a cushion does not need to be extracted to outside a bumper cover. Thus, performance of deployment of the cushion can be maintained constant, unlike the conventional art in which the cushion is deployed to outside the bumper cover, with the result that the deployment thereof may be incomplete because of contact with other objects. 
     In addition, since the cushion supports the bumper skin in the bumper cover, the external force of collision applied to the bumper skin can be effectively distributed along the bumper cover. 
     Furthermore, in the case where the cushion is deployed to outside the bumper cover, a range within which the cushion can move, particularly in the vertical direction, is increased, so that the cushion is very unstable. However, in the case of the external airbag system of the present invention, the cushion is deployed between the bumper cover and the back beam, so that a range within which the cushion can move is reduced. In addition, when the cushion is completely deployed, the bumper cover can maintain a constant shape. Therefore, the airbag system of the present invention can reliably maintain constant performance. 
     As well, in the external airbag system of the present invention, the cushion and the inflator are mounted to the back beam, so that the necessity for varying the design of a front structure of the vehicle is reduced. 
     Moreover, in the external airbag system of the present invention, variation in shape of the bumper cover between before and after the cushion is deployed is relatively small. The cushion is installed in each of the opposite sides of the bumper which are portions at which collisions are most frequent. Therefore, the present invention can be put to practical use. In addition, the present invention can absorb impact induced by a frontal collision of the vehicle and thus can substantially protect passengers in the vehicle. 
     For convenience in explanation and accurate definition in the appended claims, the terms “inner”, “interior”, and “rearward” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
     The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.