Abstract:
An airbag includes an inner panel for partitioning an interior of the airbag into a first chamber and a second chamber surrounding the first chamber. The inner panel has communication ports for communication between the first chamber and the second chamber. In an airbag inflated state, at least some of the communication ports are located in a section of the inner panel that is, with respect to a steering wheel, on a side of the steering wheel opposite from the passenger position. Gas discharged from gas discharge ports is supplied to the second chamber via the communication ports. Inflation of the second chamber, therefore, is accomplished in the early stage of the airbag deployment.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT  
       [0001]     The present invention relates to an airbag apparatus provided on a high-velocity moving body, such as a vehicle, for inflating an airbag in case of an emergency such as a collision, and for protecting a human body.  
         [0002]     In order to protect a passenger in case of an emergency such as the collision of a motor vehicle, various types of airbag apparatus such as an airbag apparatus for a driver&#39;s seat are used. The airbag apparatus for a driver&#39;s seat includes an airbag formed by stitching peripheral edges of a front panel on the passenger&#39;s side and a rear panel on the opposite side. An inflator port for receiving a distal side of an inflator is provided at a center of the rear panel. The peripheral portion of this port is mounted to a retainer by bolts, pins, rivets or the like. The rear panel is provided with a vent hole for releasing gas in the bag and absorbing an impact when the passenger seated in the driver&#39;s seat strikes against the airbag.  
         [0003]     In Japanese Unexamined Patent Application Publication No. 1-311930, an airbag is provided with an inner panel (referred to as “inner air bag” in the aforementioned reference) so as to extend between the inflator port on the rear panel and the front panel. An interior of the airbag is partitioned into a first chamber at a center and a second chamber around the first chamber. The inner air bag is provided with a communication port for bringing the first chamber and the second chamber into communication. When the inflator is activated, the first chamber is inflated first, and the second chamber is inflated subsequently.  
         [0004]     It is an object of the present invention, in an airbag having an interior partitioned into a first chamber and a second chamber, to enable inflation of the second chamber to be accomplished in the early stage of the airbag deployment.  
         [0005]     Further objects and advantages of the invention will be apparent from the following description of the invention and the associated drawings.  
       SUMMARY OF THE INVENTION  
       [0006]     An airbag according to one embodiment of the present invention is an airbag for a driver&#39;s seat being inflated by gas from a gas generator. The airbag includes a front panel to be disposed on a passenger&#39;s side; a rear panel to be disposed on an opposite side from the passenger, the front panel and the rear panel being connected to each other at peripheral edges thereof; an inner panel for partitioning an interior of the airbag into a first chamber at a center and a second chamber surrounding the first chamber; and gas generator insertion ports formed on the rear panel and the inner panel.  
         [0007]     The inner panel is formed with communication ports for bringing the first chamber and the second chamber into communication. At least part of the communication ports are disposed on the opposite side from the passenger with respect to a surface of a steering wheel on the passenger side in a state in which the airbag is inflated.  
         [0008]     An airbag apparatus according to another embodiment of the present invention includes an airbag; a gas generator having a gas exhaust port, the gas generator being disposed at least a distal side thereof in the airbag and the gas exhaust port being disposed in the airbag. The airbag is the airbag according to the first embodiment of the present invention.  
         [0009]     According to the airbag and the airbag apparatus of the present invention, part of the communication ports are disposed on the opposite side from the passenger with respect to the surface of the steering wheel on the passenger side in a state in which the airbag is inflated. Therefore, gas in the first chamber is supplied quickly to the second chamber, and the second chamber can be inflated in the early stage of airbag deployment. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a cross-sectional view of an airbag and an airbag apparatus according to an embodiment of the invention.  
         [0011]      FIG. 2  is an exploded perspective view of the airbag and the airbag apparatus depicted in  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]     Referring now to the drawings, an embodiment of the present invention will be described.  
         [0013]      FIG. 1  is a cross-sectional view of an airbag for the driver&#39;s seat of a vehicle and an airbag apparatus according to an embodiment of the present invention.  FIG. 2  is an exploded perspective view of the airbag and the airbag apparatus depicted in  FIG. 1 .  
         [0014]     An airbag  10  includes a front panel  12 , a rear panel  14 , a first inner panel  22 A, and a second inner panel  22 B, which are formed of a circular woven cloth respectively. The front panel  12  and the rear panel  14  have the same diameter, and are formed into a bag shape by being stitched together at outer peripheral edge portions thereof by a seam  15  of yarn or the like. The stitched portion has an annular shape formed around the outer peripheries of the front panel  12  and the rear panel  14 .  
         [0015]     The rear panel  14  is provided with an inflator (gas generator) port  16  and a vent hole  18 . The inflator port  16  is arranged at a center of the rear panel  14 . Provided around the inflator port  16  are bolt insertion holes  20 .  
         [0016]     The first inner panel  22 A and the second inner panel  22 B are provided inside the airbag  10 . The first and second inner panels  22 A,  22 B are disposed substantially concentrically with the front panel  12  and the rear panel  14 , and outer peripheral edge portions thereof are stitched together by a seam  23 B of yarn or the like. An inner peripheral edge of the first inner panel  22 A on the side of the front panel  12  (a peripheral edge of the inner panel  22 A on the distal side in a state in which the airbag  10  is inflated) is stitched with an intermediate portion between the center portion and the peripheral portion of the front panel  12  by a seam  23 A of yarn or the like.  
         [0017]     An inflator insertion port  24 , which is disposed substantially concentrically with the inflator port  16  on the rear panel  14 , is provided at a center portion of the second inner panel  22 B on the side of the rear panel  14  (a portion on the rear end of the second inner panel  22 B in a state in which the airbag  10  is inflated). These ports  16 ,  24  have substantially the same diameter. Provided around the port  24  on the inner panel  22 B are bolt insertion holes  26  which are aligned with the bolt insertion holes  20  on the rear panel  14 .  
         [0018]     Communication ports  28  are provided on the second inner panel  22 B at positions relatively close to the outer peripheral edge thereof, and communication ports  27  are provided on the inner peripheral side thereof. The communication ports  28  may be provided on the first inner panel  22 A.  
         [0019]     A peripheral edge portion of the inflator port  24  on the second inner panel  22 B is aligned with a peripheral edge portion of the inflator port  16  on the rear panel  14 , and then aligned with a peripheral edge portion of an inflator mounting port  32  of a retainer  30 . Then, the peripheral edge portions of the inflator ports  24 ,  16  are fixed to the retainer  30  through the bolt insertion holes  26 ,  20 . Accordingly, the peripheral edge portion of the inflator port  24  on the second inner panel  22 B is connected to the peripheral edge portion of the inflator port  16  on the rear panel  14 , the outer peripheral edge portions of the first and second inner panels  22 A,  22 B are connected together, and the inner peripheral edge portion of the first inner panel  22 A is connected to the front panel  12 .  
         [0020]     The first and second inner panels  22 A,  22 B partition an interior of the airbag  10  into a first chamber  1  at a center thereof and a second chamber  2  which surrounds the first chamber  1 . The first chamber  1  is positioned inside the inner panels  22 A,  22 B.  
         [0021]     The communication ports  27  are located on the opposite side from the passenger with respect to the surface of a steering wheel  50  on the passenger side in a state in which he airbag is inflated. In other words, in  FIG. 1 , the communication ports  27  are arranged below a virtual plane connecting an upper end surface of the steering wheel  50  in the drawing.  
         [0022]     In this embodiment, the communication ports  27  are formed at positions on extensions of the gas discharging directions of an inflator  36 , described later, disposed in the first chamber  1  via the inflator ports  16 ,  24 , that is, at positions opposing gas discharge ports  36   a  of the inflator  36 .  
         [0023]     In this embodiment, as shown in  FIG. 2 , the communication ports  27  and the communication ports  28  are formed at regular intervals circumferentially of the airbag at four positions each. The communication ports  27  are shifted from the communication ports  28  in circumferential phase about a center of the airbag.  
         [0024]     It is also applicable to attach reinforcing patches or the like at the peripheral edge portions of the ports  16 ,  24 , the communication ports  27 ,  28  and/or the vent holes  18 .  
         [0025]     The retainer  30  for mounting the airbag  10  is provided with an inflator mounting port  32  at a center and bolt insertion ports  34  in the periphery thereof.  
         [0026]     The inflator  36  has a substantially columnar shape, and is provided with the gas discharge ports  36   a  on a side peripheral surface on a distal side in a direction of a cylinder axis. In this embodiment, the gas discharge ports  36   a  are provided at regular intervals circumferentially of the inflator  36  at four positions. The inflator  36  is adapted to discharge gas from the gas discharge ports  36   a  in the discharging directions.  
         [0027]     A flange  38  for fixing the inflator is formed so as to project from the side peripheral surface at a midsection (rear side from the gas discharge ports  36   a ) of the inflator  36  in the direction of a cylinder axis. The flange  38  is provided with bolt insertion holes  40 . The inflator  36  is fitted to the inflator mounting port  32  of the retainer  30  at a distal side thereof.  
         [0028]     When mounting the airbag  10  to the retainer  30 , the peripheral edge portions of the inflator ports  16 ,  24  of the rear panel  14  and the second inner panel  22 B are pressed against the peripheral edge portion of the inflator mounting port  32  of the retainer  30  by a holding ring  42 . A distal side of the inflator  36  fitted to the inflator mounting port  32  is inserted into the first chamber  1  via the inflator ports  16 ,  24 . The gas discharge ports  36   a  provided at the distal side of the inflator  36  oppose the communication ports  27  of the second inner panel  22 B, respectively.  
         [0029]     In this case, stud bolts  44  of the holding ring  42  are inserted into the bolt insertion ports  26 ,  20 ,  34 ,  40 , and nuts  46  are tightened on distal ends thereof, so that the second inner panel  22 B, the airbag  10 , and the inflator  36  are fixed to the retainer  30 . Then, the airbag  10  is folded and a module cover  48  is mounted to the retainer  30  so as to cover the folded body of the airbag  10 , whereby the airbag apparatus is configured. The airbag apparatus is installed inside the steering wheel  50  of a motor vehicle.  
         [0030]     Upon collision of the vehicle, the inflator  36  is activated and gas is exhausted into the airbag  10 . The airbag  10 , being inflated by the gas, presses and opens the module cover  48 , and is deployed into a cabin of the vehicle to protect the passenger in the driver&#39;s seat.  
         [0031]     In the airbag  10 , since the communication ports  27  for bringing the first chamber  1  and the second chamber  2  into communication are disposed on the retainer  30  side with respect to the surface of the steering wheel  50  on the passenger side, the exhaust gas from the inflator  36  is introduced into the second chamber  2 , and the second chamber  2  is inflated in the early stage of airbag deployment.  
         [0032]     In particular, according to the present embodiment, the communication ports  27  are positioned on the extensions of the gas discharging directions of the inflator  36  as shown in  FIG. 1 , the gas from the inflator  36  is directly discharged toward the portion near the communication ports  27  and then is flowed into the second chamber  2  from the communication ports  27 . Therefore, since the discharged gas from the inflator  36  is flowed directly into the second chamber  2 , the second chamber  2  is inflated quickly in the early stage of airbag deployment.  
         [0033]     When the passenger strikes against the inflated airbag  10 , the gas in the first chamber  1  and the second chamber  2  flows out through the communication ports  28  or the vent hole  18 , whereby an impact is absorbed.  
         [0034]     The above-described embodiment is only an example of the present invention, and hence the present invention is not necessarily limited to the embodiment. For example, although four each of the gas discharge ports  36   a  and the communication ports  27  are provided in the above-described embodiment, the numbers of those are not limited to four. Although the communication ports  27  are arranged on the extensions in the gas discharging directions of all the gas discharge ports  36   a  of the inflator  36 , the communication ports  27  may be arranged only on the directions of extensions of part of the gas discharge ports  36   a . Alternatively, the part of the communication ports may be arranged at positions shifted from the directions of extensions of the gas discharge ports  36   a , and there may exist a communication port which does not oppose the gas discharge port  36   a.    
         [0035]     Although the communication ports  28  are arranged at positions apart from the port  24  in the above-described embodiment, the communication ports  28  may also be disposed on the retainer  30  side with respect to the surface of the steering wheel  50  on the passenger side.  
         [0036]     In the present invention, a rectifier cloth for guiding gas from the inflator to the communication ports  27  may be provided in the first chamber  1 .  
         [0037]     Although the communication ports  28  are provided on the second inner panel  22 B in the above-described embodiment, the communication ports  28  may be provided on the first inner panel  22 A. The communication ports  28  may also be provided both on the first inner panel  22 A and the second inner panel  22 B. The communication ports  28  may be arranged at positions corresponding to the positions of the communication ports  27 .  
         [0038]     Although the above-described embodiment is an example in which the present invention is applied to the airbag for the driver&#39;s seat or the airbag apparatus for the driver&#39;s seat, the present invention may be applied to an airbag and airbag apparatus of other various applications.  
         [0039]     The disclosure of Japanese Patent Application No. 2004-379929 filed on Dec. 28, 2004, is incorporated herein.