Abstract:
A covering member for an airbag device includes a cover body having a door section that is opened when an airbag is inflated, and a backplate integrated with the back face of the cover body. A hinge section is formed in the backplate to bend when the door section is opened. The hinge section is formed of a flexible component to allow the door section to bend easily.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT  
       [0001]     The present invention relates to airbag devices and covering members thereof that are disposed in fast moving bodies such as automobiles, and in particular, it relates to airbag devices and covering members thereof that are suitable for passenger airbag devices. Specifically, the present invention relates to covering members including door sections and airbag devices including the covering members.  
         [0002]     A passenger airbag device is disposed in front of a front passenger seat, which includes a container having an opening in the front thereof, an airbag accommodated in the container, a gas generator for inflating the airbag, and a covering member that covers the front of the container. When the gas generator ejects gas and the airbag is inflated, the covering member is opened by the airbag that pushes the covering member. Thus, the airbag is deployed in the vehicle cabin.  
         [0003]     A covering member including an instrument panel serving as a plastic cover body, a plastic airbag bracket serving both as a backplate, and a connecting member fixed to the back face of the instrument panel by vibration welding is disclosed in Japanese Unexamined Patent Application Publication No. 2002-12116. This airbag bracket is connected to an airbag case serving as a container.  
         [0004]     According to Japanese Unexamined Patent Application Publication No. 2002-12116, the airbag bracket includes a mounting section connected to the airbag case and a back-face section fixed to the back face of a door section of the instrument panel. The mounting section and the back-face section are integrated via a U-shaped hinge section, and composed of the same synthetic resin. The hinge section allows the door section to start open smoothly.  
         [0005]     An object of the present invention is to provide a covering member that allows a back face in a backplate, the back face being fixed to a door section of a cover body, to start opening very easily during opening of the door section, and to provide an airbag device including the covering member.  
         [0006]     Further objects and advantages of the invention will be apparent from the following description of the invention.  
       SUMMARY OF THE INVENTION  
       [0007]     A covering member for an airbag device according to a first aspect of the invention includes a cover body having a door section that is opened when an airbag is inflated, and a backplate integrated with the back face of the cover body. In the invention, at least a hinge section in the backplate, which is bent when the door section is opened, is formed of a flexible component.  
         [0008]     In the covering member according to a second aspect, which is dependent on the first aspect, the backplate includes a first backplate integrated with the door section of the cover body and a second backplate, separated from the first backplate and integrated with a peripheral section of the cover body enclosing the door section. The first backplate and the second backplate are connected by the flexible component.  
         [0009]     A covering member for an airbag device according to a second invention (third aspect) includes a cover body having a door section that is opened when an airbag is inflated, and a backplate integrated with the back face of the cover body. The backplate is integrated with a peripheral section of the cover body enclosing the door section, and a flexible component extends along the back face of the door section, and is fixed to the backplate and the back face of the door section.  
         [0010]     In the covering member according to a fourth aspect, which is dependent on any one of the first to third aspects, the flexible component is a mesh, a sheet, or a metallic component.  
         [0011]     In the covering member according to a fifth aspect, which is dependent on any one of the first to fourth aspects, the cover body is a lid or an instrument panel.  
         [0012]     An airbag device according to the present invention (sixth aspect) includes a container having an opening in the front thereof, an airbag accommodated in the container, a gas generator for inflating the airbag, and a covering member that covers the front of the container. In the airbag device, the covering member is made according to the present invention.  
         [0013]     In the covering member of the airbag according to the first aspect and an airbag device including the same, the hinge section of the backplate is composed of a flexible material, and thus the door section starts opening smoothly when the cover body is opened.  
         [0014]     According to the second aspect, the first backplate fixed to the door section of the cover body and the second backplate fixed to the peripheral section of the cover body are separate components, and the backplates are connected to each other by the flexible component. Therefore, when the cover body is opened, the door section starts opening very smoothly without any or almost any flexing resistance from the first and second backplates.  
         [0015]     According to the third aspect, the backplate is not fixed to the door section of the cover body, and only the flexible component is fixed to the door section of the covering body. Therefore, when the cover body is opened, the door section starts opening smoothly without flexing resistance from the backplate.  
         [0016]     When the flexible component is formed of a mesh, a sheet, or a metallic component, the door section can start opening considerably more smoothly.  
         [0017]     The cover body may be either a lid or an instrument panel. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a cross-sectional view of a passenger airbag device according to an embodiment.  
         [0019]      FIG. 2  is a cross-sectional view of a passenger airbag device according to another embodiment. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     Embodiments of the present invention will now be described with reference to the drawings.  FIG. 1  is a cross-sectional view of a passenger airbag device according to an embodiment. The right side in  FIG. 1  is adjacent to the passenger, and the left side is adjacent to a windshield.  
         [0021]     A passenger airbag device  1  includes a container  2  that is approximately rectangular when viewed in plan, a folded airbag  3  disposed inside the container  2 , and an approximately columnar inflator  4  for inflating the airbag  3 . The airbag  3  is connected to the bottom portion of the container  2  via an airbag retaining plate  3 P extending along the bottom surface of the container  2 .  
         [0022]     An instrument panel  5  covers an opening adjacent to the top of the container  2 , and a tear line  5   a  from which cleavage starts is formed on the back face of the instrument panel  5 . Both sides of the tear line  5   a  are defined as door sections  5   d  that are opened when the airbag  3  is inflated. A peripheral section  5   s  encloses the door sections  5   d.    
         [0023]     A backplate unit  10  is fixed to the back face of the instrument panel  5  by vibration welding or the like. The backplate unit  10  includes first backplates  11  fixed on the back face of the door sections  5   d , a second backplate  12  fixed on the peripheral section  5   s  enclosing the door sections  5   d , and a footboard  13  extending from the second backplate  12  so as to stand straight. The first backplates  11 , the second backplate  12 , and the footboard  13  are separate components, and gaps are provided between the first backplates  11  and the second backplate  12 . The first backplates  11 , the second backplate  12 , and the footboard  13  are composed of synthetic resin.  
         [0024]     Furthermore, the backplate unit  10  includes flexible components  14  that connect the first backplates  11  and the second backplate  12 . The flexible components  14  are formed of meshes composed of plastic fibers or metal wires, plastic sheets, metal sheets, or the like. First ends of the flexible components  14  are fixed to the first backplates  11  by embedding or the like, and second ends of the flexible components  14  are fixed to the second backplate  12  by embedding or the like.  
         [0025]     As shown in the drawing, base ends of the first backplates  11  are adjacent to the second backplate  12 , and leading ends of the first backplates  11  extend to the vicinity of the edge of the tear line  5   a.    
         [0026]     The footboard  13  is a plate extending approximately perpendicular to the instrument panel  5 . The footboard  13  includes openings  15  for attaching hook portions  21  of fixtures  20  (described below).  
         [0027]     The fixtures  20  are fixed on edge portions of the container  2  adjacent to the windshield and adjacent to the passenger by welding or the like. The approximately L-shaped hook portions  21  are integrally formed at ends of the fixtures  20  adjacent to the instrument panel  5 . The footboard  13  and the container  2  are connected by fitting the hook portions  21  into the openings  15  of the footboard  13 .  
         [0028]     In this airbag device  1  having the above-described structure, when the inflator  4  ejects gas and the airbag  3  is inflated, the door sections  5   d  cleave along the tear line  5   a  such that the door sections  5   d  start opening outward in the directions of arrows θ. Thus, the airbag  3  expands in front of the passenger to restrain the passenger.  
         [0029]     When the door sections  5   d  start opening, the first backplates  11  integrated with the door sections  5   d  start opening, and the flexible components  14  are bent. The flexible components  14  can be bent very easily, and do not apply resistance when the door sections  5   d  starts opening. Therefore, the door sections  5   d  can start opening very smoothly. Since the first backplates  11  and the second backplate  12  are connected via the flexible components  14 , the door sections  5   d  are not blown off even when large stress is concentrated in the vicinity of connections between the peripheral section  5   s  and the door sections  5   d.    
         [0030]      FIG. 2  is a cross-sectional view of an airbag device  1 A according to another embodiment.  
         [0031]     In this embodiment, a backplate unit  10 A does not include first backplates  11 , but includes only a second backplate  12  and footboard  13 . The second backplate  12  is fixed to the back face of a peripheral section  5   s  of an instrument panel  5 .  
         [0032]     First ends of flexible components  14 A are fixed to the second backplate  12  by embedding or the like. Second ends of the flexible components  14 A extend along the back faces of door sections  5   d , and are fixed on the back faces of the door sections  5   d  by bonding or the like.  
         [0033]     As shown in the drawing, the first ends of the flexible components  14 A are embedded in the second backplate  12  on the sides of the peripheral section  5   s  adjacent to the passenger and adjacent to the windshield. The second ends of the flexible components  14 A extend to the vicinities of a tear line  5   a.    
         [0034]     Structures other than these components are the same as those shown in  FIG. 1 , and components having the same reference numerals or symbols correspond to the same components.  
         [0035]     Also in this embodiment, when an inflator  4  ejects gas, the door sections  5   d  open outward in the directions of arrows θ. At this time, the door sections  5   d  can start opening very smoothly since the flexible components  14 A can easily be bent. Moreover, since the flexible components  14 A are fixed to both the door sections  5   d  and the peripheral section  5   s,  the door sections  5   d  are not blown off.  
         [0036]     The above-described embodiments are merely examples for carrying out the present invention, and embodiments other than those shown in the drawings are permissible within the scope of the present invention. For example, only one door section may be provided by forming the tear line  5   a  along the peripheral section  5   s  adjacent to the passenger. As a matter of course, three or more door sections that are opened in three or four directions may also be provided.  
         [0037]     Moreover, the backplate unit is fixed to the instrument panel  5  in the above-described embodiments, but it may be fixed to a lid of the airbag device.  
         [0038]     The disclosure of Japanese Patent Application No. 2005-255205 filed on Sep. 2, 2005 is incorporated herein as a reference.