Abstract:
A gas generated by an inflator is supplied through a branching pipe to first and second air bags, which are deployed from a side of a seat to a space between an inner surface of a side of a vehicle compartment and an occupant. A one-way valve mounted in the branching pipe permits the gas to move from the second air bag to the first air bag and inhibits a back flow of the gas, whereby the internal pressure in the first air bag can be maintained higher than that in the second air bag, to thereby restrain the occupant&#39; waist more strongly than the occupant&#39;s breast. Moreover, the gas generated by the single inflator is diverted by the branching pipe and supplied to the two air bags. Therefore, the two air bags can be deployed while minimizing the number of the inflator.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a side air bag device comprising a plurality of air bags which are accommodated in folded states in a side of a seat for an occupant and which are expanded by a gas generated by an inflator upon side collision of a vehicle to be deployed between an inner surface of a side of a vehicle compartment and the occupant.  
           [0003]    2. Description of the Related Art  
           [0004]    A conventional side air bag devices is known, for example, from U.S Pat. No. 5,464,246 and U.S. Pat. No. 6,349,964. An air bag in the side air bag device described in U.S Pat. No. 5,464,246 is formed into a cylindrical shape and adapted to be deployed to connect an upper end of a seat back and a front end of a seat cushion, thereby restraining an occupant&#39;s body from a side of the breast to a side of the waist. An air bag in the side air bag device described in U.S Pat. No. 6,349,964 is divided into upper and lower chambers so that an occupant is effectively restrained by setting the internal pressure in the upper chamber at a lower value and the internal pressure in the lower chamber at a higher value.  
           [0005]    The side air bag device described in U.S Pat. No. 5,464,246 is provided in each seat and comprises the single air bag having a uniform internal pressure, and hence it is impossible to adjust a restraint force in such a manner that the hardness of the air bag can be varied in correspondence to each site of an occupant&#39;s body. On the other hand, the side air bag device described in U.S. Pat. No. 6,349,964 has the following problem: a difference in internal pressure is generated by setting different open areas of openings through which the gas flows from the inflator into the upper and lower chambers, but the internal pressure in the entire air bag eventually becomes uniform, because the two chambers communicate with each other.  
         SUMMARY OF THE INVENTION  
         [0006]    Accordingly, it is an object of the present invention to appropriately set the restraint force of the air bag of the side air bag device in accordance with the positional relationship to the occupant&#39;s body.  
           [0007]    To achieve the above object, according to a first feature of the present invention, there is provided a side air bag device comprising a plurality of air bags which are accommodated in folded states in a side of a seat for an occupant and which are expanded by a gas generated by an inflator upon side collision of a vehicle to be deployed between an inner surface of a side of a vehicle compartment and the occupant, wherein internal pressures in the plurality of deployed air bags are different from one another.  
           [0008]    With the above arrangement, the internal pressures in the plurality of air bags deployed from the side of the seat to a space between the inner surface of the side of the vehicle compartment and the occupant. Therefore, the restraint force of each air bag can be appropriately set in accordance with the positional relationship to the occupant&#39;s body.  
           [0009]    According to a second feature of the present invention, in addition to the first feature, the gas generated by the single inflator is diverted by a branching pipe and supplied to the plurality of air bags.  
           [0010]    With the above arrangement, the gas generated by the single inflator is diverted by a branching pipe and supplied to the plurality of air bags, and hence the plurality of air bags can be deployed while minimizing the number of the inflator.  
           [0011]    According to a third feature of the present invention, in addition to the second feature, a one-way valve is mounted in an outlet of the branching pipe communicating with any one of the air bags, thereby inhibiting a back flow of the gas from the one air bag.  
           [0012]    With the above arrangement, the one-way valve is mounted in an outlet of the branching pipe communicating with any one of the air bags, and hence the back flow of the gas from the one air bag can be inhibited, whereby the internal pressure in the one air bag can be maintained higher than that in the other air bags.  
           [0013]    According to a fourth feature of the present invention, in addition to the third feature, the side air bag device includes a first air bag deployed to a side of a waist of the occupant, and a second air bag deployed to a side of a breast of the occupant, and the one-way valve is mounted on the outlet of the branching pipe communicating with the first air bag.  
           [0014]    With the above arrangement, of the first air bag deployed to the side of the occupant&#39;s waist and the second air bag deployed to the side of the occupant&#39;s breast, the one-way valve is mounted in the outlet of the branching pipe communicating with the first air bag. Therefore, the internal pressure in the first air bag can be maintained higher than that in the second air bag to restrain the occupant&#39;s breast more strongly than the occupant&#39;s waist.  
           [0015]    According to a fifth feature of the present invention, in addition to any of the first to third features, the side air bag device includes a first air bag deployed to a side of a waist of the occupant, and a second air bag deployed to a side of a breast of the occupant, the first air bag being deployed from a seat cushion, and the second air bag being deployed from a seat back.  
           [0016]    With the above arrangement, the first air bag is deployed from the seat cushion to the side of the occupant&#39;s waist, and the second air bag is deployed from the seat back to the side of the occupant&#39;s breast, thereby minimizing an influence to the deployed shapes of the first and second air bags provided by a reclining angle of the seat back with respect to the seat cushion. Especially, because the first air bag is deployed from the seat back, even if the first air bag is made longer in a longitudinal direction, a bearing force against a lateral load can be sufficiently ensured, and the occupant&#39;s waist can be further effectively restrained.  
           [0017]    According to a sixth feature of the present invention, in addition to the first feature, the plurality of air bags are expanded by the gas supplied from corresponding inflators, respectively.  
           [0018]    With the above arrangement, the plurality of air bags are expanded by the gas supplied from th corresponding inflators, respectively, and hence the pressures in the deployed air bags can be differentiated with ease.  
           [0019]    A front seat  11  in each of embodiments corresponds to a seat of the present invention, and first and second air bags  12  and  13  in each of the embodiments correspond to the air bags of the present invention.  
           [0020]    The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    FIGS.  1  to  4 B show a first embodiment of the present invention, wherein  
         [0022]    [0022]FIG. 1 is a side view of a front seat in which a side air bag device is mounted;  
         [0023]    [0023]FIG. 2 is an enlarged view of a portion indicated by  2  in FIG. 1; and  
         [0024]    [0024]FIG. 3 is a view taken in a direction of an arrow  3  in FIG. 2;  
         [0025]    [0025]FIGS. 4A and 4B are views for explaining the operation during deployment of an air bag;  
         [0026]    FIGS.  5  to  7 B show a second embodiment of the present invention, wherein  
         [0027]    [0027]FIG. 5 is a perspective view of a branching pipe;  
         [0028]    [0028]FIG. 6 is a sectional view taken along a line  6 - 6  in FIG. 5; and  
         [0029]    [0029]FIGS. 7A and 7B are views for explaining the operation during deployment of an air bag;  
         [0030]    FIGS.  8  to  10  show a third embodiment of the present invention, wherein  
         [0031]    [0031]FIG. 8 is a side view of a front seat in which a side air bag device is mounted;  
         [0032]    [0032]FIG. 9 is an enlarged view of a portion indicated by  9  in FIG. 8; and  
         [0033]    [0033]FIG. 10 is a view taken in a direction of an arrow  10  in FIG. 9; and  
         [0034]    [0034]FIG. 11 is a side view of a front seat in which a side air bag device according to a fourth embodiment is mounted. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    A first embodiment of the present invention will now be described with reference to FIGS.  1  to  4 B.  
         [0036]    As shown in FIG. 1, a side air bag device is disposed in a right side of a front seat  11  of an automobile, namely, in a side opposed to a front door and a center pillar, and includes a first air bag  12  and a second air bag  13 . The first air bag  12  is deployed so that it extends to connect a vertically central portion of the seat back  14  to a front end of a seat cushion  15 , and protects a side of a waist of an occupant. The second air bag  13  is deployed so that it extends to connect an upper end of a seat back  14  to the front end of the seat cushion  15 , and protects a side of a breast of the occupant. The first and second air bags  12  and  13  in folded states before deployment are embedded in the right sides of the seat back  14  and the seat cushion  15 , as shown by dashed lines, and are each deployed in such a manner that it breaks a sewn portion of a skin of the front seat  11  by a pressure of expansion.  
         [0037]    As can be seen in FIGS. 2 and 3, a columnar inflator  16  is fixed to the right side of a front portion of the seat cushion  15 . An F-shaped branching pipe  17  is fixed to a front end of the inflator  16 . The branching pipe  17  includes a collecting portion  18  extending forwards from the inflator  16 , a first branch portion  19  extending upwards from the middle of the collecting portion  18 , and a second branch portion  20  extending upwards from a front end of the collecting portion  18 . A lower end of a front portion of the first air bag  12  and a lower end of a one-way valve  21  are fitted over an outer periphery of the first branch portion  19  and fixed by a fixing band  19   a . A lower end of a front portion of the second air bag  13  is fitted over an outer periphery of the second branch portion  20  and fixed by a fixing band  20   a . The one-way valve  21  is formed into a pipe shape by superposing two oblong base fabrics of the same material as base fabrics of the first and second air bags  12  and  13  and sewing opposite side edges of the base fabrics at  21   a ,  21   a . A lower end of the one-way valve  21  is fitted over the first branch portion  19  in a state in which it is covered by an inner periphery of the lower end of the front portion of the first air bag  12 .  
         [0038]    When an acceleration equal to or larger than a predetermined value is detected upon the side-collision of the vehicle including the side air bag device of the above-described structure, a high-pressure gas generated by the inflator  16  is supplied to the collecting portion  18  of the branching pipe  17 , thereby expanding the first and second air bags  12  and  13  connected to the first and second branch portions  19  and  20  diverging from the collecting portion  18 . The first and second air bags  12  and  13  break the sewn portions of the skins of the seat back  14  and the seat cushion  15 , so that the first air bag  12  is deployed to protect the side of the occupant&#39;s waist, and the second air bag  13  is deployed to protect the side of the occupant&#39;s breast.  
         [0039]    As shown in FIG. 4A, when the first air bag  12  is expanded, the one-way valve  21  is cylindrically expanded to permit the gas to pass therethrough. The internal pressures in the first and second air bags  12  and  13  change in correspondence to occupant restraint loads. When the internal pressure in the second air bag  13  becomes higher than that in the first air bag  12 , the one-way valve  21  is opened to transfer the gas in the second air bag  13  into the first air bag  12 , as shown in FIG. 4A. When the internal pressure in the first air bag  12  becomes higher than that in the second air bag  13 , the one-way valve  21  is crumpled to be closed and inhibits the transfer of the gas in the first air bag  12  into the second air bag  13 . As a result, the internal pressure in the first air bag  12  becomes higher than that in the second air bag  13 , so that the first air bag  12  abutting against the side of the waist can be made harder than the second air bag  13  abutting against the side of the breast, to thereby effectively restrain the occupant&#39;s body. Since the one-way valve  21  is formed by sewing the opposite side edges of the two base fabrics at  21   a ,  21   a , the one-way valve  21  is liable to be flattened and reliably closed.  
         [0040]    As described above, the first and second air bags  12  and  13  are mounted in the side air bag device, and the internal pressure in the two air bags  12  and  13  are different from each other, so that a restraint force can be appropriately set in correspondence to a region of the occupant&#39;s body. Moreover, the gas generated by the single inflator  16  is diverted by the branching pipe  17  to expand the two air bags  12  and  13 , so that it is possible to reduce the number of parts to provide reduction in cost and size, as compared with a case where two inflators are mounted.  
         [0041]    A second embodiment of the present invention will now be described with reference to FIGS.  5  to  7 B. The second embodiment is different from the first embodiment with respect to the structure of a one-way valve  21  mounted at a first branch portion  19  of a branching pipe  17 , but the structure of all the other components is the same as that in the first embodiment.  
         [0042]    The one-way valve  21  in the second embodiment is comprised of a cylindrical valve housing  22  closed at its upper end by an upper wall  22   a , and a valve member  23  vertically movably disposed in the valve housing  22 . The valve member  23  includes a downward-convex conical body  23   a  and four arm portions  23   b  protruding radially from an outer periphery of the body  23   a . The arm portions  23   b  are slidably fitted into four quadrilateral openings  22   b  formed in a side of the valve housing  22 .  
         [0043]    Thus, when the inflator  16  generates the gas and when the internal pressure in the second air bag  13  becomes higher than that in the first air bag  12 , the arm portions  23   b  of the valve member  23  of the one-way valve  21  are guided and moved upwards in the openings  22   b  of the valve housing  22 , as shown in FIG. 7A, so that the gas is supplied through the thus-opened openings  22   b  into the first air bag  12 . On the other hand, when the internal pressure in the first air bag  12  becomes higher than that in the second air bag  13 , the arm portions  23   b  of the valve member  23  of the one-way valve  21  are guided and moved downwards in the openings  22   b  of the valve housing  22 , so that the openings  22   b  are closed to close the one-way valve  21 , whereby the gas in the first air bag is inhibited from moving into the second air bag  13 .  
         [0044]    According also to the second embodiment, the internal pressure in the first air bag  12  can be increased to be higher than that in the second air bag  13 , and the same function and effect as in the first embodiment can be achieved.  
         [0045]    A third embodiment of the present invention will now be described with reference to FIGS.  8  to  10 .  
         [0046]    In each of the side air bag devices according to the above-described first and second embodiments, the first and second air bags  12  and  13  in the folded states are embedded in and astride the sides of the seat back  14  and the seat cushion  15 , and opposite ends of the deployed first and second air bags  12  and  13  extend to connect the seat back  14  and the seat cushion  15  to each other. In the side air bag device according to the third embodiment, a first air bag  12  is deployed upwards from the seat cushion  15  to protect an occupant&#39;s waist, and a second air bag  13  is deployed forwards from the seat back  14  to protect an occupant&#39;s breast.  
         [0047]    A common inflator  16  for deploying the first and second air bags  12  and  13  is disposed in a rear portion of the seat cushion  15 , and an F-shaped branching pipe  17  is fixed to a rear end of the inflator  16 . The branching pipe  17  includes a collecting portion  18  extending rearwards from the inflator  16 , a first branch portion  19  extending upwards from the middle of the collecting portion  18 , and a second branch portion  20  extending upwards from a rear end of the collecting portion  18 . A rear end of the first air bag  12  and a lower end of a one-way valve  21  are fitted over an outer periphery of the first branch portion  19  and fixed by a fixing band  19   a . A lower end of a bellows pipe  24  is fitted over an outer periphery of the second branch portion  20  and fixed by a fixing band  20   a . The bellows pipe  24  extends upward within the seat back  14  and is connected to the second air bag  13 . The one-way valve  21  is formed into a pipe shape by superposing two base fabrics of the same material as that of the base fabrics of the first and second air bags  12  and  13  and sewing opposite side edges of the base fabrics at  21   a ,  21   a . A lower end of the of the one-way valve  21  is fitted over the first branch portion  19  in a state in which it is covered by an inner periphery of a rear end of the first air bag  12 .  
         [0048]    According to the third embodiment, in addition to the function and effect in each of the first and second embodiments, even if the reclining angle of the seat back  16  with respect to the seat cushion  15  is changed, the influence to the deployed shapes of the first and second air bags  12  and  13  can be minimized, because the first air bag  12  is supported only in the seat cushion  15  and the second air bag  13  is supported only in the seat back  14 .  
         [0049]    Moreover, since the first air bag  12  is deployed from the seat cushion  15 , even if the first air bag  12  is formed to be longer in a longitudinal direction, the connection thereof with the seat cushion  15  is longer, so that the resisting force of the first air bag  12  to a lateral load becomes large, thereby further effectively restraining the occupant&#39;s waist.  
         [0050]    A fourth embodiment of the present invention will now be described with reference to FIG. 11.  
         [0051]    The fourth embodiment is a modification to the third embodiment. As in the third embodiment, a first air bag  12  is deployed upwards to protect an occupant&#39;s waist, and a second air bag  13  is deployed forwards to protect an occupant&#39;s breast. However, the first air bag  12  is deployed by a gas supplied from an exclusive inflator  16  mounted in the seat cushion  15 , and the second air bag  13  is deployed by a gas supplied from an exclusive inflator  16 ′ mounted in the seat back  14 .  
         [0052]    Since the first and second air bags  12  and  13  are deployed by the corresponding inflators  16  and  16 ′, respectively, as described above, the internal pressures in the first and second air bags  12  and  13  do not interfere with each other at all and can be set differently from each other with ease.  
         [0053]    Although the embodiments of the present invention have been described in detail, it will be understood that various modifications in design may be made without departing from the spirit and scope of the invention defined in the claims.  
         [0054]    For example, the side air bag device in each of the embodiments includes the two air bags  12  and  13 , but may include three or more air bags.