Abstract:
An airbag system includes an airbag having an occupant side surface facing an occupant and an opposite side surface facing a vehicle body in an inflated state, and having an interior partitioned into a plurality of chambers including at least an upper chamber and a lower chamber; a gas generator disposed in the airbag; and a gas distributor having a discharge port for discharging gas from the gas generator into at least the upper chamber and the lower chamber. The gas distributor has a gas-distributing connecting line extending substantially linearly for connecting the occupant side surface and the opposite side surface of the airbag.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
     The present invention relates to an airbag system for protecting an occupant of a vehicle such as an automobile in the event of a crash. More particularly, the present invention relates to an airbag system including an airbag having an interior partitioned into a plurality of chambers. 
     A conventional airbag system is constructed to inflate an airbag toward an occupant by a gas generator so that the inflated airbag receives a body of the occupant. Japanese Patent Publication (Kokai) No. 2000-177527 has disclosed a structure in which a lower part of an airbag is inflated at a higher inner pressure than that of an upper part for receiving a lumbar part of the occupant.  FIG. 5  is a side view of a seat equipped with the airbag system.  FIG. 6  is an enlarged sectional view of a section  6  of the side airbag system shown in  FIG. 5 . 
     An airbag  18  is partitioned into an upper chamber  20  and a lower chamber  22  with a seam  24 . A rear end of the seam  24  is positioned slightly away from a rear rim of the airbag  18 . A cylindrical gas distributor  30  is placed in a space between the rear end of the seam  24  and the rear rim of the airbag  18 . A rod-like gas generator  36  is placed in the gas distributor  30 . Upper and lower ends of the gas distributor  30  are formed with pipe clips  32  and  34  for fixing the gas generator  36 . The pipe clips  32  and  34  seal a portion between the gas generator  36  and the gas distributor  30 . The pipe clips  32  and  34  are attached to mounting sections  26  of a seat back  14 . 
     The gas distributor  30  has upper-chamber discharge ports  42  for discharging gas from the gas generator  36  into the upper chamber  20 , and lower-chamber discharge ports  44  for discharging the gas into the lower chamber  22 . The lower-chamber discharge ports  44  are larger than the upper-chamber discharge ports  42 . Therefore, when the gas generator  36  is activated, the airbag  18  is inflated so that the upper chamber  20  has an inner pressure about 0.5 bar and the lower chamber  22  has an inner pressure about 1.5 bars. 
     The side airbag system disclosed in Japanese Patent Publication (Kokai) No. 2000-177527 includes the gas distributor  30 , thereby increasing a cost. In the side airbag system, the discharge ports  42  and  44  are directed forward of the seat. Accordingly, the gas from the gas generator  36  first inflates the airbag  18  forward of the seat and then inflates the airbag  18  vertically, so that the airbag  18  is inflated vertically later. 
     In view of the problems described above, an object of the present invention is to provide an airbag system with a simple structure at a low cost. 
     It is another object of the present invention to provide an airbag system in which the airbag is quickly inflated vertically. 
     Further objects and advantages of the invention will be apparent from the following description of the invention. 
     SUMMARY OF THE INVENTION 
     According to the present invention, an airbag system includes an airbag having an occupant side surface facing an occupant and an opposite side surface facing a vehicle body in an inflated state, and having an interior partitioned into a plurality of chambers including at least an upper chamber and a lower chamber; a gas generator disposed in the airbag; and a gas distributor having a discharge port for discharging gas from the gas generator into at least the upper chamber and the lower chamber. The gas distributor has a gas-distributing connecting line extending linearly for connecting the occupant side surface and the opposite side surface of the airbag. 
     In the present invention, the airbag system has the gas distributor constructed by connecting the occupant side surface and the opposite side surface of the airbag. Accordingly, it is not necessary to provide a separate gas distributor, thereby making the airbag system simple and easy to produce. The airbag system of the invention protects the occupant in case of a side collision as well as roll over. 
     According to the invention, the gas-distributing connecting line extends vertically, and a gas generator housing chamber is formed between the gas-distributing connecting line and a side rim of the airbag. The housing chamber has a gas discharge port communicating with the lower chamber downwardly at a lower end thereof. The lower-chamber discharge port is larger than an upper-chamber discharge port. 
     In the present invention, the side airbag system has the lower-chamber discharge port directed downwardly. Therefore, when the gas generator is activated, the airbag is inflated downwardly quickly. Also, the lower-chamber discharge port is larger than the upper-chamber discharge port. Therefore, the lower chamber is inflated at a higher inner pressure than that of the upper chamber at an early stage of the inflation. In this case, the gas generator may be formed in a rod shape having a gas jet port at one end thereof, and may be disposed in the housing chamber with the gas jet port arranged downwardly. With such an arrangement, the gas generator ejects the gas easily into the lower chamber to inflate the lower chamber early. 
     According to the invention, the housing chamber may be arranged between the upper chamber and the side rim of the airbag. Accordingly, it is possible to increase a capacity of the lower chamber. The housing chamber may extend vertically along the side rim of the airbag, so that the gas generator inflates the housing chamber to deploy the airbag upward quickly. 
     According to the invention, a lower part of the gas-distributing connecting line may be positioned close to the side rim of the airbag. Accordingly, it is possible to control an amount of the gas supplied to the lower chamber and the upper chamber. 
     According to the invention, the airbag may be partitioned into a plurality of chambers with a partitioning connecting line extending linearly and connecting the occupant side surface and the opposite side surface. The gas-distributing connecting line and the partitioning connecting line may be overlapped. Accordingly, it is possible to make the airbag system further simple and easy to produce. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a vehicle seat equipped with an airbag system according to an embodiment of the present invention; 
         FIG. 2(   a ) is a sectional view of the airbag taken along line  2 - 2  in  FIG. 1 ; 
         FIG. 2(   b ) is a sectional view of the airbag taken along line  2 ( b )- 2 ( b ) in  FIG. 2(   a ); and 
         FIG. 2(   c ) is a sectional view of the airbag taken along line  2 ( c )- 2 ( c ) in  FIG. 2(   a ); 
         FIGS. 3(   a ) and  3 ( b ) are sectional views of airbags according to other embodiments of the invention; 
         FIGS. 4(   a ) and  4 ( b ) are sectional views of airbags according to further embodiments of the invention; 
         FIG. 5  is a side view of a conventional airbag system; 
         FIG. 6  is a sectional view of the conventional airbag system shown in  FIG. 5 ; and 
         FIG. 7  is a side view of an airbag according to a still further embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereunder, embodiments of the present invention will be described with reference to the accompanying drawings.  FIG. 1  is a perspective view of a vehicle seat equipped with an airbag system according to an embodiment of the present invention.  FIG. 2(   a ) is a sectional view of the airbag taken along line  2 ( a )- 2 ( a ) in  FIG. 1 ,  FIG. 2(   b ) is a sectional view of the airbag taken along line  2 ( b )- 2 ( b ) in  FIG. 2(   a ), and  FIG. 2(   c ) is a sectional view of the airbag taken along line  2 ( c )- 2 ( c ) in  FIG. 2(   a ). 
     As shown in  FIG. 1 , an airbag  1  is inflated along a window side of a seat  10 . The seat  10  includes a seat cushion  11 , a seat back  12 , and a headrest  13 . A casing (not shown) of the airbag system is provided at a side of the seat back  12 , in which the airbag  1  is housed in a folded state and covered with a module cover (not shown). 
     The airbag  1  is formed such that a sheet such as a cloth and a resin sheet (cloth in the embodiment) is formed in a bag shape. An interior of the airbag  1  is partitioned into a lower chamber  1   a  and an upper chamber  1   b  with a linear connecting portion (a seam  2  in this embodiment). The seam  2  connects an occupant side surface  1   p  of the airbag  1  and an opposite side surface  1   q  together. The seam  2  has a substantially L-shape having a substantially horizontal section  2   a  and a vertical section  2   b.    
     As shown in  FIG. 2(   a ), the vertical section  2   b  of the seam  2  extends vertically and is positioned slightly away from a rear end of the airbag  1 . A vertically extending housing chamber  4  is formed at a portion between the vertical section  2   b  and the rear rim of the airbag  1 . A front end of the horizontal section  2   a  of the seam  2  is connected to a front rim of the airbag  1 . 
     The housing chamber  4  houses a rod-shaped gas generator  3 . A longitudinal direction of the gas generator  3  is aligned in a vertical direction. The gas generator  3  includes gas jet ports  3   b  at a lower end thereof. Two stud bolts  3   a  project from the gas generator  3  backward of the airbag  1  through the rear rim of the airbag  1 . The stud bolts  3   a  are fastened to the casing of the airbag system with nuts. With this arrangement, the gas generator  3  and the airbag  1  are fixed to the casing. 
     As shown in  FIG. 2(   a ), a clearance for a gas passage is provided between an outer circumference of the gas generator  3  and the vertical section  2   b  of the seam  2 . A gas discharge port  4   a  is provided at a lower end of the housing chamber  4  between a rear end of the horizontal section  2   a  and the rear rim of the airbag  1 , and opens downwardly into the lower chamber  1   a . A gas discharge port  4   b  is provided at the upper end of the housing chamber  4  between an upper end of the vertical section  2   b  and an upper rim of the airbag  1 , and opens forward into the upper chamber  1   b . The upper chamber  1   b  includes a vent hole  5 . 
     In the airbag system with such a structure, when a vehicle receives an impact or rolls over, the gas generator  3  ejects the gas. The gas flows into the lower chamber  1   a  and the upper chamber  1   b  from the gas discharge ports  4   a  and  4   b  to inflate the lower chamber  1   a  and the upper chamber  1   b , respectively. Thus, the airbag  1  deploys along the window side of the seat  10 , as shown in  FIG. 1 . 
     In the airbag system, the housing chamber  4  extends vertically, and the lower-chamber discharge port  4   a  is directed downwardly. Also, the gas jet ports  3   b  are arranged downwardly in the vicinity of the lower-chamber discharge port  4   a . Therefore, when the gas generator  3  is activated, the lower chamber  1   a  of the airbag  1  is first inflated quickly, then the housing chamber  4  deploys vertically quickly, and thereafter the upper chamber  1   b  is inflated. 
     The lower gas-discharge port  4   a  has a size larger than that of the upper gas-discharge port  4   b . Accordingly, a larger amount of the gas is supplied to the lower chamber  1   a  at a higher pressure than that in the upper chamber  1   b . Furthermore, the gas jet ports  3   b  of the gas generator  3  are arranged at the lower end of the gas generator  3 . Accordingly, it is possible to supply a larger amount of the gas to the lower chamber  1   a  at a higher pressure. As a result, the lower chamber  1   a  is inflated early at a high inner pressure to receive a lateral movement of the lumbar part of the occupant. The upper chamber  1   b  is inflated at a lower inner pressure than that of the lower chamber  1   a , thereby receiving an upper part of the occupant softly. 
     According to the invention, it is possible to make the arrangement simple in which the lower chamber  1   a , the upper chamber  1   b , and the housing chamber  4  are partitioned with seam  2 , thereby making it easy to produce. 
       FIGS. 3(   a ) and  3 ( b ) are sectional views of side airbag systems according to other embodiments of the invention, respectively. In an airbag  1 A shown in  FIG. 3(   a ), the gas discharge port  4   a  of the seam  2  (a connecting section of the horizontal section  2   a  and the vertical section  2   b ) closely contacts the rear rim of the airbag  1 A. Accordingly, the gas discharge port  4   a  connecting to the lower chamber  1   a  has an opening smaller than that in  FIG. 2 . 
     With this arrangement, it is possible to control an inflation speed and an inner pressure of the lower chamber  1   a  by adjusting a distance between the seam  2  and the airbag  1 A. It is also possible to change a size of the gas discharge port  4   b  to control an inflation speed and an inner pressure of the upper chamber  1   b  and the lower chamber  1   a  by adjusting a distance between the upper end of the vertical section  2   b  of the seam  2  and the upper rim of the airbag  1  (not shown). In the embodiment, the gas discharge port  4   b  may be disposed in the middle of the vertical section  2   b  of the seam  2 , as in an airbag  1 B shown in  FIG. 3(   b ). 
     In the embodiments described above, the airbags  1 ,  1 A, and  1 B are partitioned into two chambers, i.e. the upper chamber  1   b  and the lower chamber  1   a . Alternatively, the airbags  1 ,  1 A, and  1 B may be partitioned into three or more chambers. 
       FIGS. 4(   a ) and  4 ( b ) are sectional views showing airbags  1 C and  1 D, respectively. Each of the airbags  1 C and  1 D has a substantially horizontal seam  6 , and a middle chamber  1   c  is provided between the upper chamber  1   b  and the lower chamber  1   a . A front end of the seam  6  is connected to front rims of the airbags  1 C and  1 D, respectively. In the airbag  1 C, the vertical section  2   b  of the seam  2  has a gas discharge port  4   c  communicating with the middle chamber  1   c  between the horizontal section  2   a  and the seam  6 . In the airbag  1 D, the gas discharge port  4   c  is provided in the seam  6 . 
     Other arrangements of the airbags  1 C and  1 D are the same as those of the airbag  1  shown in  FIGS. 1 ,  2 ( a ) and  2 ( b ). Accordingly, the same reference numerals in  FIGS. 4(   a ) and  4 ( b ) indicate the same components as those in  FIGS. 1 ,  2 ( a ) and  2 ( b ). 
     In the embodiments shown in  FIGS. 4(   a ) and  4 ( b ), the gas discharge port  4   a  is directed downwardly in the lower chamber  1   a , and the housing chamber  4  extends vertically. Accordingly, when the gas generator  3  is activated, the airbags  1 C and  1 D are first inflated vertically quickly. In the airbag  1 C shown in  FIG. 4(   a ), the gas flows into the middle chamber  1   c  from the gas discharge port  4   c  at a rear of the middle chamber  1   c . Therefore, the middle chamber  1   c  is inflated forward quickly. In the airbag  1 D shown in  FIG. 4(   b ), when the occupant plunges into the inflated upper chamber  1   b , a part of the gas in the upper chamber  1   b  flows into the middle chamber  1   c  through the gas discharge port  4   c , thereby absorbing an impact applied to the occupant. 
     According to the invention, the seam  24  may extend diagonally, as shown in an airbag  1 E in  FIG. 7 . 
     The embodiments described above are only examples of the invention and various modifications may be possible in the invention. For example, the invention may include three or more partitioning seams to form four chambers or more. 
     As described above, the present invention provides the airbag system that can be produced at a low cost. According to the invention, the airbag can be quickly inflated vertically. 
     While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.