Abstract:
A cover for an airbag container includes a main cover body overlying a back plate and connectors. The connectors are configured to extend away from the main cover body to be connected to the container. The main cover body and the back plate include weakened regions configured to separate to permit an airbag to deploy into a vehicle cabin. The back plate, main cover body and connectors are separate non-integral elements of the cover.

Description:
BACKGROUND  
         [0001]    The present invention relates to airbag apparatuses used in high-speed moving objects such as vehicles or the like and covers of the airbag apparatuses, and particularly relates to an airbag apparatus suitable for use as an airbag apparatus for a passenger seat and a cover of the airbag apparatus. More specifically, the present invention relates to a cover having a main cover body and a back plate, and to an airbag apparatus including the cover.  
           [0002]    A typical airbag apparatus for a passenger seat is placed in front of the passenger seat and includes a container which is open at the front side, an airbag stored in the container, a gas generator for inflating the airbag, and a cover which covers the front side of the container. When the gas generator is activated and ejects gas, the airbag inflates and pushes the cover. Accordingly, the cover opens and the airbag expands into the vehicle cabin.  
           [0003]    Japanese Unexamined Patent Application Publication No. 2002-12116 (incorporated by reference herein) discloses a cover including an instrument panel composed of a synthetic resin which corresponds to a main cover body and an airbag bracket composed of a synthetic resin which corresponds to a component which serves both as a back plate and connectors. The airbag bracket is fixed on the back surface of the instrument panel by vibration welding, and is connected to an airbag housing which corresponds to the container.  
           [0004]    According to the Japanese Unexamined Patent Application Publication No. 2002-12116, although the instrument panel and the bag bracket can be composed of different materials, the component which serves both as the back plate and the connectors is integrally formed of a single synthetic resin.  
         SUMMARY OF THE INVENTION  
         [0005]    An object of the present invention is to provide an airbag apparatus in which a cover, a back plate and connectors may be composed of different materials.  
           [0006]    A cover of an airbag apparatus according to an exemplary embodiment of the present invention includes a main cover body having a door portion which opens when an airbag inflates and a back plate which is connected to the back surface of the main cover body, and connectors for connecting the cover to a container of the airbag apparatus which are provided separately from the back plate.  
           [0007]    An airbag apparatus according to an alternative embodiment of the present invention further includes a container which is open at the front side, an airbag stored in the container, a gas generator for inflating the airbag, and a cover according to the present invention which covers the front side of the container.  
           [0008]    In the cover for the airbag apparatus according to an embodiment of the present invention, the back plate is continuous to the main cover body and the connectors are provided separately from the back plate. Therefore, the back plate and the connectors may be composed of different materials, and the back plate, which is largely bent when the airbag inflates, may be composed of a suitable material. Accordingly, the expansion performance of the airbag apparatus increases.  
           [0009]    In the above-described cover, each of the connectors preferably include a front piece placed on the back plate and a leg piece which projects rearward from the front piece behind the main cover body and which is connected to the container. In addition, preferably, the main cover body is provided with projecting pieces which project rearward from the back surface of the main cover body, and the projecting pieces are inserted through openings formed in the front pieces of the connectors and openings formed in the back plate. As a result, the connecting strength between the main cover body and the connectors can be increased. In this case, each of the front pieces of the connectors may be provided with a pair of upright pieces which project from the edges of the opening formed in the front piece, and the upright pieces of each of the front pieces may be connected to one of the projecting pieces while the upright pieces and the projecting piece are placed on each other. Accordingly, the connecting strength between the connectors and the main cover body can be further increased.  
           [0010]    According to another embodiment of the present invention, a central portion of the back plate may be fixed to the door portion of the main cover body and edge portions of the back plate are formed continuously to the central portion such that the edge portions can be bent. In addition, the edge portions may be provided with the openings and the projecting pieces are inserted through the openings by placing the edge portions on the back surface of the main cover body. As a result, the projecting pieces can easily project rearward from the back plate. In addition, when the door portion of the main cover body opens, tensile stress applied to step portions of the back plate can be received by the projecting pieces.  
           [0011]    According to various embodiments of the present invention the main cover body may be a lid or an instrument panel.  
           [0012]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    These and other features, aspects, and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below.  
         [0014]    [0014]FIG. 1 is a sectional view of an airbag apparatus for a passenger seat according to an embodiment.  
         [0015]    [0015]FIG. 2 is a sectional view of the airbag apparatus shown in FIG. 1 in a state in which the airbag is inflated.  
         [0016]    [0016]FIG. 3 is a perspective view of a main cover body and a back plate.  
         [0017]    [0017]FIG. 4 is an exploded perspective view of a cover.  
         [0018]    [0018]FIG. 5 is an assembly diagram of the cover.  
         [0019]    [0019]FIG. 6 is a top view of an embodiment of the back plate according to an embodiment of the present invention.  
         [0020]    [0020]FIG. 7 is a top view of the back plate according to an alternative embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0021]    An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view of an airbag apparatus for a passenger seat according to the embodiment, FIG. 2 is a sectional view of the airbag apparatus shown in FIG. 1 in a state in which an airbag is inflated, FIG. 3 is a perspective view of a main cover body and a back plate, FIG. 4 is an exploded perspective view of a cover, and FIG. 5 ( a ), ( b ), ( c ), and ( d ) are assembly diagrams of the cover.  
         [0022]    The airbag apparatus  10  includes a container  12  which is open at the front side, an airbag  14  which is stored in the container  12  in a folded state, a gas generator  16  for inflating the airbag  14 , and a cover  18  which covers the front side of the container  12 .  
         [0023]    The cover  18  includes a main cover body  20  positioned at the front, a back plate  30  provided on the back surface of the main cover body  20 , and connectors  40  provided behind the back plate  30 .  
         [0024]    The main cover body  20  has a door portion  22  which faces the container  12  at the central region of the main cover body  20 . The door portion  22  is provided with a tear line  24  which is a concavity, such as a groove or the like, used for breaking the door portion  22 .  
         [0025]    In addition, the main cover body  20  has flange portions  26  at the peripheral regions of the main cover body  20  which protrude beyond the sides of the container  12  at an area in front of the container  12 . The flange portions  26  are provided with projecting pieces  28  which projects substantially perpendicularly from the back surfaces of the flange portions  26 . Each of the projecting pieces  28  is provided with through holes  28   a  for receiving bolts  60  which will be described below. The main cover body  20  is composed of a synthetic resin, and is formed integrally with the projecting pieces  28 .  
         [0026]    The back plate  30  includes a central portion  32  which is placed on the door portion  22  of the main cover body  20 , a slit  34  which is formed in the central portion  32  such that it is positioned directly behind the tear line  24 , edge portions  36  which are continuous to the central portion  32 , and openings  38  which are formed in the edge portions  36  and through which the projecting pieces  28  are inserted. The back plate  30  is also composed of a synthetic resin, and the central portion  32  of the back plate is formed integrally with the door portion  22  of the main cover body  20 .  
         [0027]    In order to form the central portion  32  and the door portion  22  integrally with each other, the main cover body  20  and the back plate  30  are formed by a co-injection molding process in which the main cover body  20  and the back plate  30  are successively formed by injection molding such that the central portion  32  and the door portion  22  are formed integrally with each other.  
         [0028]    According to an alternative embodiment of the present invention, the main cover body  20  and the back plate  30  may first be formed separately, and then be combined together by a fixing method such as vibration molding.  
         [0029]    As shown in FIG. 6, the back plate  30  may include a pair of plates  31  separated by the slit  34 . Alternatively, as shown in FIG. 7, the back plate  30  may include a single plate having a series of aligned slits or openings  35 .  
         [0030]    As shown in FIG. 5( a ), the back plate  30  is formed such that the edge portions  36  are approximately perpendicular to the central portion  32 . The edge portions  36  can be bent with respect to the central portion  32 , as shown in FIG. 5( b ).  
         [0031]    The connectors  40  are composed of a synthetic resin, and each of the connectors  40  includes a front piece  42  which is placed on one of the edge portions  36  of the back plate  30 , a leg piece  44  which projects rearward from the front piece  42 , an opening  46  through which one of the projecting pieces  28  is inserted, and a pair of upright pieces  48  which project from both edges of the opening  46 . The upright pieces  48  are provided with through holes  48   a  for receiving the bolts  60 , and the leg piece  44  is provided with openings  44   a  which engage with hook members  64  provided on the container  12 .  
         [0032]    As shown in FIG. 3, when the cover  18  is assembled, each of the edge portions  36  which projects from the central portion  32  is bent in the direction shown by θ in FIGS. 3 and 5( a 0, and is placed on the flange portion  26  of the main cover body  20  such that the projecting piece  28  is inserted into the opening  38  (FIG. 5( b )). Then, the front piece  42  of one of the connectors  40  is placed on this edge portion  36  such that the projecting piece  28  is inserted into the opening  46  (FIGS. 4 and 5( c )).  
         [0033]    Next, U-shaped clip fittings  50  are fitted to the pair of upright pieces  48  and  48 . Each of the clip fittings  50  has a pair of parallel plates  52  and  52 , and each of the parallel plates  52  and  52  is provided with a bolt hole  54 . One the bolt holes  54  and  54  has an internal thread.  
         [0034]    The upright pieces  48  and  48  are clamped with the clip fittings  50 , and the bolts  60  are screwed into the bolt holes  54  and the through holes  48   a  and  28   a . Accordingly, the connectors  40  and the edge portions  36  of the back plate  30  are combined with the main cover body  20 , and the cover  18  is completed.  
         [0035]    The cover  18  is engaged with the container  12  from the front. By engaging the hook members  64  of the container  12  with the openings  44   a  formed in the leg pieces  44  of the connectors  40 , the cover  18  is connected to the container  12  and the airbag apparatus  10  is completed.  
         [0036]    In the airbag apparatus  10  which is constructed as described above, when the gas generator  16  is activated and ejects gas, the airbag  14  inflates and the door portion  22  breaks along the tear line  24 . Thus, the door portion  22  opens outward as shown in FIG. 2. At this time, stress concentration occurs at regions around the boundaries between the door portion  22  and the flange portions  26 , so that the main cover body  20  breaks at the regions around these boundaries and two halves of the door portion  22  are separated from the flange portions  26 . Since the back plate  30  is connected to the door portion  22  and the edge portions  36  of the back plate  30  are restrained by the projecting pieces  28 , the two halves door portion  22  can be prevented from being released.  
         [0037]    According to an alternative embodiment of the present invention, the two halves of the door portion  22  may also be continuous to the flange portions  26 .  
         [0038]    When the door portion  22  starts to open, the back plate  30  is bent at regions around the boundaries between the central portion  32  and the edge portions  36 , and the door portion  22  and the central portion  32  opens together. Accordingly, the airbag  14  expands into the vehicle cabin to cushion and protect the passenger.  
         [0039]    In the cover  18  of this airbag apparatus  10 , the main cover body  20 , the back plate  30 , and the connectors  40  may be composed of different materials, and each of them is composed of a material having characteristics suitable for the use. For example, the connectors  40  may be composed of a high-strength material, the back plate  30  may be composed of a highly flexible material, and the main cover body  20  may be composed of a material which provides attractive appearance and good tactile feel.  
         [0040]    The main cover body  20  may be composed of, for example, polypropylene, modified polyphenylene oxide (PPO), or AIBS. The back plate  30  may be composed of, for example, a thermoplastic elastomer. The connectors  40  may be constructed of a thermoplastic elastomer which has a higher strength than that used as the material of the back plate  30  or polypropylene.  
         [0041]    According to an embodiment of the present invention, the projecting pieces  28  are engaged with the openings  38  formed in the edge portions  36  of the back plate  30 . As a result, the back plate  30  is attached to the main cover body  20  and the connectors  40  with high strength. In addition, as shown in FIGS.  5 ( a )- 5 ( d ), the cover  18  can be extremely easily assembled.  
         [0042]    Although a lid which is larger than the container  12  is used as the main cover body  20  in the above-described embodiment, an instrument panel may also be used as the main cover body  20 . In addition, although the projecting pieces  28  and the upright pieces  48  are fixed by using the clip fittings  50  and the bolts  60 , the projecting pieces  28  and the upright pieces  48  may also be fixed by attaching the clip fittings by hot-air welding or ultrasonic welding.  
         [0043]    As described above, according to the present invention, each of the main cover body, the back plate, and the connectors may be composed of a material suitable for the use, and an advantage in that the expansion performance of the airbag increases can be obtained.  
         [0044]    The priority application, Japanese Patent Application No. 2002-262960 filed on Sep. 9, 2002, is hereby incorporated by reference herein in its entirety.  
         [0045]    Given the disclosure of the present invention, one versed in the art would appreciate that there may be other embodiments and modifications within the scope and spirit of the invention. Accordingly, all modifications attainable by one versed in the art from the present disclosure within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is to be defined as set forth in the following claims.