Abstract:
An airbag canister vent is attached to or resides within an airbag module of an automobile. The module has a housing, within which resides a gas generator, an airbag, a tether cord, and a housing vent valve configured to close in accordance with the tether length that connects the airbag and the housing vent valve. The tension or any slack in the tether is governed by the discharge distance of the airbag from the canister. The canister vent may be a rotating disk that gradually closes as the airbag moves toward a seat occupant or a movable ball valve with a tether pin that remains open until the bag is discharged far enough from the canister to pull a tether pin from the ball causing the pressurized gas in the canister to forcibly lodge the ball against the vent hole wall thereby forming a seal and closing the valve.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an airbag system for a motor vehicle and more particularly to a mechanical vent in an airbag deployment canister.  
       BACKGROUND OF THE INVENTION  
       [0002]     Inflatable interior automotive safety devices are known as supplemental restraint systems (SRS) and supplemental inflatable restraints (SIR), or more generically as “airbags.” While current airbag systems have generally proven to be satisfactory for their applications, each is associated with its share of limitations. One limitation with current airbag systems is their venting systems. Because current airbag venting systems are located in the airbags themselves, current airbags are more complicated than they otherwise would be if the venting system were not located in the airbag. Additionally, when airbag venting systems are located in the airbag, the options for locating the venting systems are limited since the venting system location must take into consideration airbag deployment and passenger position relative to the deploying airbag. Furthermore, current airbag systems provide various stages of airbag inflation and cushioning to an impacting passenger by controlling the release of the fluid gas that fills the airbag. However, cushioning may be dependent upon the position of the passenger relative to the airbag.  
         [0003]     What is needed is a device that does not suffer from the above limitations. This, in turn, will provide a device that eliminates the need to use airbag venting systems in the airbags. Furthermore, a device will be provided that permits varying amounts of fluid gas to fill the airbag depending upon its stage of deployment, taking into consideration the relative position of a passenger to the deploying airbag. Finally, a device will be provided that permits fluid gas to be immediately discharged from the airbag system upon airbag deployment in order to provide a desirable level of cushioning to a passenger impacting the airbag, relative to the position of the passenger impacting the airbag.  
       SUMMARY OF THE INVENTION  
       [0004]     In accordance with the teachings of the present invention, an adjustable airbag canister vent is disclosed. A vehicle airbag having a tether resides within an airbag canister. An adjustable canister vent coupled to the tether activates in accordance with tension on the tether during airbag deployment to prevent gas from exiting the canister to fill the airbag at a faster rate.  
         [0005]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0007]      FIG. 1  is a top view of an automobile depicting the in-dash location of a front passenger supplemental restraint system relative to a vehicle front passenger seat according to the present invention;  
         [0008]      FIG. 2  is a side view of a discharging front supplemental restraint system with a front passenger sitting relatively close to the front dash area and the supplemental restraint system according to the present invention;  
         [0009]      FIG. 3  is a side view of a discharging front supplemental restraint system with a front passenger sitting relatively far from the front dash area and the supplemental restraint system according to the present invention;  
         [0010]      FIG. 4  is a perspective view of a supplemental restraint system canister depicting the location of a side discharge vent, in its open position, according to the present invention;  
         [0011]      FIG. 5  is a perspective view of a supplemental restraint system canister depicting the location of a bottom discharge, ball vent valve according to the present invention;  
         [0012]      FIG. 6  is a perspective view from the interior of the supplemental restraint canister depicting the side rotary vent, the airbag, and the airbag retainer according to the present invention;  
         [0013]      FIG. 7  is a side view of the side rotary vent in a partially open position according to the present invention;  
         [0014]      FIG. 8  is a side view of the side rotary vent in a fully closed position according to the present invention;  
         [0015]      FIG. 9  is a perspective view of a ball vent valve depicting a ball retainer and a ball releasing pin according to the present invention;  
         [0016]      FIG. 10  is a bottom perspective view of a tab locking feature of the ball vent valve according to the present invention;  
         [0017]      FIG. 11  is a perspective view of the ball vent valve in its open position depicting a tether pin and a ball pin according to the present invention;  
         [0018]      FIG. 12  is a side view of the ball vent valve in its closed position depicting a ball and a ball pin according to the present invention;  
         [0019]      FIG. 13  is a top perspective view of an open ball vent valve depicting a retainer and a conical ball according to the present invention; and  
         [0020]      FIG. 14  is a bottom perspective view of a closed ball vent valve depicting a retainer and a conical ball according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0022]     Turning to  FIG. 1 , a vehicle  10  is depicted in which a passenger air bag system  14  of the present invention resides. Vehicular air bag systems are inflatable interior automotive safety devices and are also known as supplemental restraint systems (SRS), supplemental inflatable restraints (SIR), or more generically as “airbags,” which will be used throughout this writing. The airbag system  14  of the present invention is shown imbedded or recessed within the dash  16  of the vehicle interior  12 . While the location of the airbag system  14  is in the dash  16 , and cannot move, the location of the passenger front seat bottom  18  and passenger front seat back  20  are mobile and play a role in the operative workings of the present invention. More specifically, it is the position of a passenger on the passenger front seat bottom  18  that governs the operation of the passenger airbag system  14  of the present invention.  
         [0023]     Turning now to  FIGS. 2-8 , a first embodiment of the present invention will be described.  FIG. 2  depicts a vehicle occupant  30  in a more forward position, with a gap  28  between the occupant and the seat back  20 , relative to the occupant  31  depicted in  FIG. 3  who is embedded within the seat bottom  18  and seat back  20  in a more aft position. Additionally, in  FIG. 3 , the seat bottom  18  is adjusted farther away from the dash  16  as a user-selected option relative to the position of the seat bottom  18  in  FIG. 2 .  
         [0024]     Continuing with  FIG. 2  and  FIGS. 4-8 , the operative workings of the first embodiment will be described. During a front impact event of the vehicle  10 , the occupant  30  will tend to move forward in the direction of arrow  44 . When the vehicle  10  undergoes a front end impact, the airbag system  14  will discharge an airbag  64  from the airbag canister  15  residing in the dash  16  when an inflator  66 , residing in an inflator recession  22  of the airbag canister  15 , discharges a fluid gas from a plurality of inflator discharge holes  68  causing the opening of the airbag canister cover  24 . The airbag  64  moves toward the occupant  30  and may be guided by the vehicle windshield  34  above the airbag. The airbag has a tether  40 , a first end of which is attached to the airbag  64  and a second end of which is attached to a tether tab  84  of a rotary vent  70 , which will now be described.  
         [0025]      FIGS. 4 through 8  depict a rotary vent  70  in a side wall of the airbag canister  15 . The rotary vent  70  has a mounting plate  72  and may have mounting holes  74  for attaching the rotary vent  70  to the airbag canister  15  with rivets, screws or other suitable fasteners. Alternatively, the rotary vent  70  may be welded to the wall of the airbag canister  15 . The rotary vent  70  is shown adjacent to the non-inflated, folded airbag  64  in  FIG. 4 , with the inflator recession  22 , which houses the inflator  66 , positioned under the airbag  64 .  
         [0026]     Referring to  FIG. 2 , when the vehicle  10  undergoes impact and the airbag  64  discharges and fills with fluid gas, the tether  40  begins to have its slack taken-up, although the tether  40  still has slack. When the airbag  64  is in intermediate airbag position  36 , the rotary vent  70  is in its fully open position as indicated in  FIG. 4 . When the rotary vent  70  is open, fluid gas can escape from the airbag canister  15  interior to the airbag canister exterior. When the rotary vent  70  is open, gas is filling the airbag, but at the same time, gas is being vented through the open areas  80 ,  82  of the rotary vent  70 . This provides the airbag with the proper inflation characteristics. As the airbag  64  inflates, it moves to airbag position  38 , where the tether  42  still has an amount of slack.  
         [0027]     Before the conclusion of the discussion of the operative workings of the rotary vent  70 , an explanation of how the airbag  64  is situated relative to the rotary vent  70  will be explained. Turning to  FIG. 6 , with the rotary valve  70  shown in its fully open position, an airbag retainer  90  having an airbag retainer groove  92  is shown. The airbag retainer  90  attaches to an interior side wall of the airbag canister  15  using the retainer hole  91  and any suitable fastener such as a screw or rivet. Alternatively, the airbag retainer  90  could be welded to the interior of the airbag canister  15 . The airbag retainer  90  traverses around the opening  81  in the side wall through which fluid gas may discharge. The airbag  64 , shown in phantom, is secured within the airbag retainer groove  92  in such a way that the interior of the airbag  64  can vent gas through the rotary vent  70 . That is, when the airbag  64  is secured around the rotary vent  70 , a fluid path exits from the inflator  66 , through the airbag canister  15  and within the confines of the airbag  64 , through the rotary vent  70  to the exterior of the airbag canister  15 . More specifically, the fluid gas passes through the open areas  80 ,  82  when the rotating disk  76  is in a position to permit such a venting of gas.  
         [0028]      FIG. 2  depicts a situation where the rotary vent  70  remains open and permits gas to escape from the airbag canister  15  while filling the airbag at the same time. As can be seen from  FIG. 2 , when the airbag  64  is at airbag position  36 , there is slack in the tether  40 . Likewise, when the airbag  64  is at airbag position  38 , there is also slack in the tether  42  and the rotary vent  70  remains open. At the stage of deployment of airbag position  38  of the airbag  64 , contact with the occupant  30  has been made, and the airbag  64  will not deploy any farther than airbag position  38 . At airbag position  38 , the airbag has completely discharged from the area  26  of the airbag canister  15  and cushioned the forward motion, indicated with arrow  44 , of the occupant  30 . The rotary vent  70 , through its venting during deployment, provides the proper cushioning to the occupant  30 . At no stage of deployment did the vent close for the scenario explained above and depicted in  FIG. 2 . The above description is a possible deployment scenario of the airbag when the occupant  30  is situated in a forward position on the seat bottom  18 . More specifically, during the airbag deployment scenario of  FIG. 2 , the airbag tether does not become taught, which does not prompt closing of the rotary vent  70 .  
         [0029]     With reference to  FIGS. 3-4  and  FIGS. 6-8 , a second deployment scenario will be described.  FIG. 3  depicts a scenario in which the airbag  64  is permitted to completely deploy to airbag position  52 . When the occupant  31  sits in an aft position in the seat bottom  18  and seat back  20 , as depicted with the occupant back side  46 , and for example, may have the seat bottom  18  adjusted far enough away from the dash  16  to require the airbag  64  to deploy to its farthest airbag position, such as airbag position  52 , the following deployment scenario may occur. When a vehicle  10  experiences a front impact event, the airbag  64  of  FIG. 4  will deploy to a first intermediate airbag position  48  ( FIG. 3 ). At airbag position  48 , the tether  54  has an amount of slack in it such that the rotary vent  70  of  FIG. 4  remains in its fully open position. With reference to  FIG. 6 , when the rotary vent  70  is in its open position, in addition to filling the airbag  64 , fluid gas from the inflator  66  is discharged from the plurality of discharge holes  68 , through the airbag  64  residing in the airbag canister  15 , and out through the opening  81  to outside of the canister  15 .  
         [0030]     Continuing with the airbag deployment and reference to  FIG. 3 , since the occupant  31  is far enough away from the deploying airbag  64  such that at airbag position  48 , the airbag does not yet make contact with the occupant  31 , the airbag  64  proceeds to fill with gas from the inflator  66  until the airbag  64  reaches airbag position  50 . At airbag position  50 , the tether  56  becomes taught, which causes the rotary vent  70  to begin closing as the airbag continues to fill and move towards the occupant. With reference to  FIGS. 3 and 7 , as soon as the airbag fills beyond airbag position  50 , the tether  56  tension begins rotating the rotary disk  76  which begins the closing of the open areas  80 ,  82  ( FIGS. 4 and 7 ). When the rotary vent  70  begins closing, less gas is permitted to escape from the airbag canister  15  which causes a proportionately greater amount of gas to flow into the airbag  50 . As more gas flows into the airbag  50 , the rotary disk  76  continues to rotate about point  88  which continues the closing of the open areas  80 ,  82 , which causes an even larger amount of gas to flow into the airbag.  
         [0031]     With continued reference to  FIG. 3 , since the airbag  64  at airbag position  50  has not yet made contact with the occupant  31 , the airbag continues to fill and moves toward the occupant  31 . Since the rotary disk  76  is rotating during this time, the rate of gas flowing into the airbag  64  continues to increase. When the airbag reaches airbag position  52 , the state of the tether is as depicted by tether  58  ( FIG. 8 ). Because the rotary disk  76  continues to rotate, the angle of the tether  58  in  FIG. 8 , is different from that of  FIG. 7 . At this position, with reference to  FIG. 8 , the rotary disk  76  of rotary vent  70  may be in a fully-closed position in which all of the gas being discharged from the inflator  66  is being directed into the airbag, which enables the airbag to continue its deployment toward the occupant  31  at a more rapid pace than at previous stages when the rotary vent  70  was open. When the rotary vent  70  is closed, the normally open, open areas  80 ,  82  are closed and non longer permit the passage of inflator gas. Upon closing of the rotary vent  70 , it remains in a closed position and all of the inflator gas is used to fill the airbag at a more rapid pace than when the rotary vent  70  is open.  
         [0032]     There are multiple advantages of using a rotary vent  70  of the present invention in the airbag canister  15 . A first advantage is that when an occupant is sitting in accordance with  FIG. 2 , the open rotary vent  70  will permit gas to discharge out the rotary vent  70  open areas  80 ,  82  when the occupant  30  strikes the airbag, after the inflator  66  has stopped discharging gas. This provides a cushioned landing for the occupant. Even in the event the occupant is positioned particularly close to the dash  16  and the airbag discharges in a front end collision, when the occupant  30  makes contact with the airbag at airbag position  38 , the gas will be directed out of the rotary vent  70  open areas  80 ,  82  because the occupant  30  will prevent the airbag from expanding, and thus the gas will seek an outlet through the open areas  80 ,  82 .  
         [0033]     There are also advantages of the rotary vent  70  in an occupant arrangement according to  FIG. 3 , in which the occupant  31  is sitting relatively far away from the dash  16 . One advantage is that as the airbag continues to deploy but has not yet contacted the occupant  31  who is moving in accordance with direction arrow  60 , a taught tether will cause the rotary vent  70  to close beginning at about airbag position  50  thereby directing all of the discharging gas from the inflator  66  into the airbag to cause the bag to reach the occupant  31  at a more rapid pace and eventually reach airbag position  52 . This controlled expansion and venting feature permits the occupant  31  to take advantage of the protection offered by the airbag  52 , even if the occupant is sitting relatively far from the dash  16 . Of course, when the occupant  31  contacts the airbag at airbag position  52 , the airbag will cushion the impact of the occupant  31 .  
         [0034]     An overall advantage of the rotary vent  70 , regardless of whether the occupant is sitting relatively close to, or far from, the dash  16 , is that sensors may not needed in the seat(s) that have traditionally determined various parameters such as occupant weight and relative seat position to determine if the airbag should be in an “on” or “off” mode. Because of this advantage, a broad range of passengers may be afforded cushioned airbag protection. Another advantage is the cost of the airbag system  14 . Because the system is mechanical, and eliminates electronic sensors that may be costly to purchase, monitor and troubleshoot, there is a cost advantage to the airbag system.  
         [0035]     Turning to a second embodiment of the invention, a ball valve style vent  100  is depicted in  FIG. 5 , and in  FIGS. 9-14  as part of an airbag system  14 . As depicted in  FIG. 5 , the ball vent  100  lies under the inflator  66 , while the inflator  66  lies under the airbag  64 . Alternate arrangements are possible and the arrangement of the ball vent  100  relative to the other parts of the airbag system  14  is not to be limited to that depicted in  FIG. 5 . Because the ball vent  100  operates in accordance with the discharging gas pressure, its functioning is not dependent upon gravity and provides options regarding its placement relative to the airbag  64  and the inflator  66 .  
         [0036]     Continuing with reference to  FIG. 5 , and  FIGS. 9-14 , the operative workings of the ball vent  100  will be explained. The ball vent  100  has a tether  102 , one end of which is attached to the airbag  64  while the other end is attached to a tether pin  104 . The tether pin  104  passes through a top plate  114  and is held in position by a tether pin stop  112  that is located between the top of the tether pin  104  and the top plate  114 . The tether pin  114  passes through the center of a group of valve guide posts  116 . While  FIG. 9  depicts four valve guide posts  116 , a varying number of valve guide posts are permissible, as long as the mobile valve element  122  ( FIG. 11 ), also known as a ball  122 , which is pierced by the tether pin  104 , is held in position when in motion, which will be discussed later.  
         [0037]     Before discussing how the ball vent  100  functions as a vent of the air bag system  14 , its attachment to the air bag canister  15  will be explained. The ball vent  100  attaches to the bottom surface of the airbag canister  15  from inside of the canister  15 . The ball vent  100  has a locking post  123 , which protrudes through the bottom of the mounting plate  120 , and a locking tab  124  that protrudes from the locking post  123 . To secure the ball vent  100  to the bottom wall  108  of the airbag canister  15 , the locking post  123  is fitted through the mounting hole  131  and turned counterclockwise, when viewed from the tether pin  104 , to lock the ball vent  100  to the bottom wall  108  in a wedge fit. From the discharge side, the ball vent is turned clockwise in accordance with arrow  136 . The ball vent  100  can also be secured by fasteners such as screws, rivets, welding, etc.  
         [0038]     Now, ball vent  100  functioning as a vent during the operation of the airbag system  14  will be discussed. With reference to  FIG. 2 , when a vehicle undergoes a front end collision, the airbag  64  will discharge to a first airbag position  36  in which the tether  40  has slack. As depicted in  FIG. 2 , the occupant  30  is sitting in a forward position on the seat bottom  18  and closer to the dash  16 , relative to the occupant  31  of  FIG. 3  who is sitting in a more relaxed position and farther from the dash  16 . When the airbag  64  deploys, gas from the inflator  66  discharges through a group of inflator discharge holes  68  in the inflator  66 . Since there is slack in the tether  40 , while the fluid gas is filling the airbag  64  at airbag position  36 , and causing the airbag to move toward the occupant, who is moving toward the airbag in accordance with the arrow  44 , gas also is venting out of the airbag canister  15 . With reference to  FIGS. 10 and 11 , inflator gas exits the canister  15  through the mounting plate hole  126  and the bottom wall hole  127 .  
         [0039]     With continued reference to  FIG. 2 , as the airbag continues to discharge to airbag position  38 , the airbag makes contact with the occupant  30 . At this stage of deployment, since the ball vent  100  is still in its open position, gas continues to vent outside of the canister  15  until the inflator  66  has finished discharging gas, and the cushioned impact of the occupant  30  with the airbag at airbag position  38  has concluded. Because the occupant  30  is positioned in a more forward position, as discussed above, the ball vent  100  never closes because the tether pin  104  remains intact and is not extracted from the ball  122 . An advantage of this embodiment of the present invention is that the ball vent  100  remains open to vent gas outside of the canister  15  which provides cushioning to the impacting occupant  30  and an outlet for gas when the occupant impacts the airbag at airbag position  38 . A situation in which the ball vent  100  closes will now be discussed.  
         [0040]     With reference to  FIGS. 3, 5  and  11 - 14  a situation in which the ball vent  100  closes will be described. When the vehicle  10  undergoes a front end impact with an object, the airbag  64  may deploy. In a situation in which the occupant  31  is sitting deep in the seat bottom  18  and seat back  20 , and with the seat bottom  18  adjusted relatively far from the vehicle dash  16 , the airbag  64  first deploys to an airbag position  48 . At airbag position  48 , there is still slack in the tether  54  and the inflator  66  is propelling fluid gas into the airbag and through the open ball vent  100 . The open ball vent  100  permits gas to escape from inside the airbag canister  15  through the mounting plate hole  126  and through the bottom wall hole  127  of the canister  15 . Next, because the airbag has not yet made contact with the occupant  31 , the airbag continues inflating to airbag position  50 . At airbag position  50 , the tether is void of slack as indicated by tether  56 . At airbag position  50 , an additional feature of the present invention is invoked which will now be described.  
         [0041]     With the slack eliminated in the airbag tether  56 , the tether pin  104  of  FIG. 11  will begin to receive tension from the taught tether  56 . Still at this time, the inflator  66  is discharging gas into the airbag  64  such that the airbag continues to inflate and move toward the occupant  31 . Additionally, gas is discharging, that is, “venting” exterior to the canister  15  via the holes  126 ,  127 . As the airbag continues to inflate and move toward airbag position  52 , the tension in direction  128  of the tether  56  increases such that the tether pin  104  is extracted from the mobile valve element  122 . When the airbag is at airbag position  52 , and the tether  58  has even greater tension in it than at tether  56 , the tether pin  104  is in its extracted state and the ball  122  is forced according to arrow  121  to the position shown in  FIG. 12 . Although the size of the ball  122  will prevent it from passing through the mounting plate  120  and the bottom wall  108 , the ball  122  may be equipped with a ball pin  125  to ensure that the ball stops at the surface of the mounting plate  120 . Once the ball  122  moves in the direction of arrow  121 , the ball  122  will not move in the opposite direction as indicated by direction arrow  128 . Additional ball vent valve explanation follows.  
         [0042]     The pin is extracted from the ball  122  by bending or breaking the hook  119  due to the force of the tension in the tether  58  ( FIG. 3 ) caused by the filling airbag. The pressure inside the airbag canister  15 , caused by the inflator  66 , forces the ball  122  to travel within valve guide posts  116  of the valve guide  118  until the ball  122  stops and becomes lodged against the mounting plate  120 . This stops the flow of gas through the mounting plate hole  126  and directs all discharging gas from the inflator  66  into the airbag such that the gas discharges at a faster rate.  
         [0043]     As depicted in  FIG. 3 , the airbag is permitted to continue to inflate and move toward the occupant  31 . However, since all of the gas from the inflator  66  is being directed into the airbag at airbag position  52 , the airbag inflates at a more rapid pace to reach the occupant  31 , who is sitting relatively far away from the vehicle dash  16 . The advantage of the ball vent  100  is that when the ball  122  blocks the discharge of gas from the canister  15  through the mounting plate  120 , the airbag  52  is able to fill faster, and as a result, the airbag  52  can travel toward the occupant at a faster rate. By filling in this manner, the airbag  52  is able to provide adequate cushioned protection to the occupant  31  who sits relatively far from the dash.  
         [0044]     While the ball vent  100  is depicted in  FIGS. 10-12  as a sphere, the ball vent  100  may also employ a conical valve element  132  as depicted in  FIG. 13 . In such a case, the conical valve element  132  is forced in the direction indicated by the arrow  130 , when the tether pin  104  is pulled by the tether  102  in the direction indicated by the arrow  128 , which causes the conical valve element  132  to lodge in the mounting plate hole  126  and prevent gas from escaping though the mounting plate hole  126 . Because of its elongated conical shape, an advantage of the conical valve element  132  is that it is able to stop the flow of gas through the mounting plate hole faster than a the ball  122  of  FIG. 11  because the conical surface  134  of the conical valve element  132  begins its travel to the mounting plate hole  126  closer to the hole when the tether pin  104  is pulled.  
         [0045]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.