Abstract:
A vehicle side air curtain has an inflator, a main inflatable chamber, and an integral separate, self-contained controlled pressure chamber in limited fluid communication with the main inflatable chamber of the side air curtain and disposed for impact by the head and upper thoracic region of a vehicle occupant. The main inflatable chamber is inflated to an initial pressure within an initial impact time period immediately following actuation of the inflator and a second lower stabilized pressure thereafter to extend the duration of the pressurization of the main inflatable chamber of the side air curtain beyond the initial impact time period. The controlled pressure chamber of the side air curtain is inflated to an initial pressure substantially lower than the first pressure of the main inflatable chamber and favorable to side impact occupant protection immediately following actuation of the inflator pressure.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to a side air curtain for a motor vehicle to optimize side impact protection while simultaneously providing occupant ejection mitigation from the vehicle during a vehicle side impact or rollover event, specifically a side air curtain that includes a controlled pressure chamber that provides a variable pressure chamber throughout the course of the impact event. 
       BACKGROUND OF THE INVENTION 
       [0002]    Side air curtain systems for use in motor vehicles have been adopted to mitigate occupant ejection during motor vehicle side impact or rollover events, and are generally well-known in the art. Traditionally, such side air curtain systems have been used in combination with exterior motor vehicle components to manage and control motor vehicle impact events with external objects and rollover events. In particular, Federal Motor Vehicle Safety Standard (FMVSS) No. 226 has been promulgated to address side impact and rollover events that potentially may result in occupant ejection from the interior of the motor vehicle. In sum, where a side air curtain is employed to mitigate occupant ejection, FMVSS 226 presently requires the side air curtain to maintain pressure for up to 6 seconds after deployment. 
         [0003]    Further, side impact airbag systems have been developed to address vehicle intrusion in the event of a side impact pursuant to FMVSS 214 and to provide occupant restraint against occupant collision with interior motor vehicle components, such as the so-called A pillar, B pillar, and interior upper rail assembly. In contrast to side air curtains, however, side airbag systems are designed to deploy very rapidly after detecting the first impact event and stay inflated for only about 100 milliseconds. 
         [0004]    Since side air curtain pressure must be sustained over the 6 seconds duration of inflation, the side air curtain initial pressure is typically raised to a level sufficient to provide stiffness in the side air curtain throughout the 6 seconds set forth in the requirements of FMVSS 226. However, higher initial side air curtain pressures have been found to aggravate head impact response criteria upon initial impact. Thus, to comply with both FMVSS 214 and FMVSS 226, a lower initial pressure in the side air curtain is desirable, with a higher sustained pressure provided later in the impact event. 
         [0005]    To achieve such a goal, a dual stage inflator can be used. A first stage inflator can be used to pressurize the side air curtain to a first pressure for a limited time after the first impact, with a second stage inflator used to pressurize the side air curtain to a second, higher pressure later in the impact event to mitigate ejection. However, such a dual stage inflator system presents a cost penalty, presents significant packaging challenges, and adds weight to the motor vehicle. Hence, solutions for providing side impact occupant protection while also mitigating occupant ejection during such side impact events would be advantageous. 
         [0006]    The vehicle side air curtain disclosed herein particularly accomplishes the foregoing optimization of vehicle performance and provides a cost-efficient approach to address the problem by employing a side air curtain having an integral separate, self-contained controlled pressure chamber in the location required for compliance with FMVSS 214 in limited fluid communication with the remainder of the side air curtain. For a limited period of time, the controlled pressure chamber of the side air curtain experiences an initial pressure favorable to head impact protection during the initial impact time period, while the remainder of the side air curtain experiences a significantly higher initial pressure adapted to optimize the longer duration of the side air curtain pressurization. After the initial impact time period, the pressure differential between the controlled pressure chamber and the remainder of the side air curtain causes the pressure in each of the controlled pressure chamber and the remainder of the side air curtain to equalize at a stabilized pressure that is optimized to sustain a sufficient inflation pressure for the time required for ejection mitigation protection. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one aspect of the present disclosure, a vehicle side air curtain for a motor vehicle has an inflator, a main inflatable chamber, and an integral separate, self-contained controlled pressure chamber in limited fluid communication with the main inflatable chamber of the side air curtain and disposed for impact by the head and upper thoracic region of a vehicle occupant. The main inflatable chamber of the side air curtain is inflated to an initial pressure substantially immediately following actuation of the inflator and a second lower stabilized pressure thereafter to extend the duration of the pressurization of the main inflatable chamber of the side air curtain beyond the initial impact time period. The controlled pressure chamber of the side air curtain is inflated to an initial pressure substantially lower than the initial pressure of the main inflatable chamber of the side air curtain and to a pressure favorable to side impact occupant protection substantially immediately following actuation of the inflator. 
         [0008]    Still another aspect of the present disclosure is a side air curtain where the pressure differential between the main inflatable chamber of the side air curtain and the controlled pressure chamber causes the pressure in the controlled pressure chamber to equalize with the second stabilized pressure in the main inflatable chamber after the initial impact time period, such that the pressure of each of the controlled pressure chamber and the main inflatable chamber of the side air curtain remain at relatively elevated levels thereafter to mitigate occupant ejection. 
         [0009]    Yet another aspect of the present disclosure is a side air curtain where the initial pressure in the main inflatable chamber is at least 100 KPa within 30 milliseconds after actuation of the inflator and the second lower stabilized pressure in the main inflatable chamber is about 80 KPa within 100 milliseconds after actuation of the inflator. 
         [0010]    An additional aspect of the present disclosure is a side air curtain where the initial pressure of the controlled pressure chamber of the side air curtain is less than 20 KPa within 30 milliseconds after actuation of the inflator and the pressure of the controlled pressure chamber of the side air curtain is about 80 KPa within 100 milliseconds after actuation of the inflator. 
         [0011]    Another aspect of the present disclosure is a side air curtain where the pressure in each of the main inflatable chamber and the controlled pressure chamber is about 80 KPa at 100 milliseconds, which maintains sufficient pressure level in both for at least 6 seconds for ejection mitigation. 
         [0012]    An additional aspect of the present disclosure is a side air curtain mounted on the upper side rail assembly of the motor vehicle. 
         [0013]    A further aspect of the present disclosure is a side air curtain where the main inflatable chamber is in fluid communication with the controlled chamber via a gas vent that regulates the rate of fluid flow between the main inflatable chamber and the controlled pressure chamber. 
         [0014]    Yet a further aspect of the present disclosure is a side air curtain where the main inflatable chamber is in fluid communication with the controlled pressure chamber via a plurality of gas vents. 
         [0015]    An additional aspect of the present disclosure is a side air curtain where the main inflatable chamber comprises a plurality of interconnected cavities in fluid communication one to the other about their peripheries to form a substantially flat side panel to prevent occupant ejection and the controlled pressure chamber is disposed within the plurality of the cavities. 
         [0016]    Yet another aspect of the present disclosure is a side air curtain where the controlled pressure chamber is disposed proximate the head and upper thoracic region of a vehicle occupant when deployed. 
         [0017]    A still further aspect of the present disclosure is a side air curtain where the main inflatable chamber comprises a non-inflated vent panel that is interconnected about its periphery to the plurality of cavities. 
         [0018]    Another aspect of the present disclosure is a side air curtain where the main inflatable chamber comprises a non-inflated vent panel disposed longitudinally proximate the middle of the flat panel and the controlled pressure chamber is disposed longitudinally forward on the flat panel and proximate the head and upper thoracic region of a vehicle occupant when deployed. 
         [0019]    A yet additional aspect of the present disclosure is a side air curtain comprising an inflator, a main chamber, and an impact chamber in limited fluid communication with the main chamber, wherein the main chamber is inflated to a first pressure immediately after actuation of the inflator and a second pressure thereafter, and the impact chamber is inflated to a pressure substantially lower than the first pressure of the main chamber immediately after actuation of the inflator. 
         [0020]    A further aspect of the present disclosure is a method of mitigating occupant ejection and occupant injury, the method comprising the steps of providing a vehicle side air curtain having an inflator, a main inflatable chamber, and an integral separate controlled, self-contained pressure chamber in limited fluid communication with the main inflatable chamber of the side air curtain and disposed for impact by the head and upper thoracic region of a vehicle occupant, inflating the main inflatable chamber of the side air curtain in response to a side impact or rollover event to an initial pressure substantially immediately following actuation of the inflator and a second lower stabilized pressure thereafter to extend the duration of the pressurization of the main inflatable chamber of the side air curtain beyond the initial impact time period, inflating the controlled pressure chamber of the side air curtain to an initial pressure favorable to side impact occupant protection and substantially lower than the initial pressure of the main inflatable chamber of the side air curtain substantially immediately following actuation of the inflator, and equalizing the pressure differential between the main inflatable chamber of the side air curtain and the controlled pressure chamber after the initial impact time period to the second lower stabilized pressure, such that the pressure of each of the controlled pressure chamber and the main inflatable chamber of the side air curtain remain at elevated levels to mitigate occupant ejection. 
         [0021]    Still another aspect of the present disclosure is a method of mitigating occupant ejection and occupant injury where the initial pressure in the main inflatable chamber is at least 100 KPa within 30 milliseconds after actuation of the inflator and the second stabilized pressure in each of the main inflatable chamber and the controlled pressure chamber is about 80 KPa within 100 milliseconds after actuation of the inflator. 
         [0022]    Yet another aspect of the present disclosure is a method of mitigating occupant ejection and occupant injury where the initial pressure of the controlled pressure chamber of the side air curtain is less than 20 KPa within 30 milliseconds after actuation of the inflator and the second stabilized pressure in each of main inflatable chamber and the controlled pressure chamber is about 80 KPa within 100 milliseconds after actuation of the inflator. 
         [0023]    These and other aspects, objects, and features of the present disclosure will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    In the drawings: 
           [0025]      FIG. 1  is a side perspective view of the interior of a motor vehicle incorporating the vehicle side air curtain with a controlled pressure chamber in accordance with the present disclosure in the inflated condition; 
           [0026]      FIG. 2A  is a front side perspective view of a typical vehicle side air curtain without a controlled pressure chamber in the partially inflated condition 20 milliseconds after deployment; 
           [0027]      FIG. 2B  is a front side perspective view of a typical vehicle side air curtain without a controlled pressure chamber in the fully inflated condition 50 milliseconds after deployment; 
           [0028]      FIG. 3A  is a front side perspective view of a vehicle side air curtain with a controlled pressure chamber in accordance with the present disclosure, where the main side air curtain is in the fully inflated condition and the controlled pressure chamber is in the semi-inflated condition 20 milliseconds after deployment; 
           [0029]      FIG. 3B  is a front side perspective view of a vehicle side air curtain with a controlled pressure chamber in accordance with the present disclosure, where the main side air curtain is in the fully inflated condition and the controlled pressure chamber is in the fully inflated condition 50 milliseconds after deployment; 
           [0030]      FIG. 4  is a rear top side perspective view of the controlled pressure chamber integrated in the main side air curtain in accordance with the present disclosure; 
           [0031]      FIG. 5  is a rear top side perspective view of the interior of the bottom of one of the cavities of the main side air curtain and the gas inlets on a transition panel between the controlled pressure chamber and the main side air curtain in accordance with the present disclosure; and 
           [0032]      FIG. 6  is a graphical representation of the pressures within the main inflation chamber and the controllable pressure chamber in the initial period of inflation of the side air curtain of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0033]    For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in  FIG. 1 . However, it is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
         [0034]    Referring to  FIG. 1 , a motor vehicle  10  includes an interior occupant compartment  12  including a front seat assembly  14 , a rear seat assembly  16 , and a dashboard  18 , the occupant compartment  12  defined substantially by a floor  20 , windshield  22 , and a roof portion  24 . As is conventional, the rear end  26  of the motor vehicle  10  comprises a rear backlight  28 , such as that installed in a hatchback that may be selectively opened to allow access to a cargo area  30  situated above a cargo floor  32 . Of course, the motor vehicle  10  can employ a traditional trunk and truck lid assembly behind a rear window to enclosed the cargo area  30 . As shown in  FIG. 1 , the roof portion  24  includes an upper side rail assembly  34  to which may be mounted the side air curtain  36  in accordance with the present disclosure. 
         [0035]    As shown, the side air curtain  36  when deployed extends forward to the windshield  22  and rearward to the hatchback  28  and sufficiently downwardly so as to essentially obscure the front and rear side window assemblies (not shown). The side air curtain  36  is thus able to mitigate occupant ejection during a side impact event. As noted above, FMVSS 226 requires that the side air curtain  36 , if employed, maintains a sufficient pressure to mitigate ejection for a period of 6 seconds after impact and deployment. 
         [0036]    A standard side air curtain  36 , without the improvement disclosed herein, is shown in  FIGS. 2A-2B . Such a side air curtain  36  is commonly mounted on the interior on both sides of the motor vehicle  10  at the upper side rail assembly  34 . Preferably, a sensor (not shown) is used to send a signal to an electronic control unit to actuate an inflator  38  and initiate inflation of the side air curtain  36  through duct  40  upon impact with a side external body or a rollover event, preferably within 5 to 10 milliseconds after the impact event begins. As shown in  FIG. 6 , the typical inflation profile for a standard side air curtain  36  is an initial pressurization of less than 20 KPa about 10 milliseconds after inflation initiation, with an abrupt rise in pressure to about 60 KPa about 30 milliseconds after inflation initiation. As shown in  FIG. 2A , the side air curtain  36  is typically inflated to 30 KPa after about 20 milliseconds after inflation initiation. As shown in  FIG. 2B , the pressure in the side air curtain  36  is about 75 KPa about 50 milliseconds after inflation initiation. A final pressure of about 80 KPa is reached about 60 to 70 milliseconds after inflation, which allows maintaining sufficient pressure level for at least 6 seconds to mitigate occupant ejection. 
         [0037]    As can be seen in  FIGS. 2A-2B , the side air curtain  36  includes a plurality of inflatable cavities  42  that are interconnected one to the other about their peripheries and are in fluid communication one to the other via passages  44 . A center portion of the side air curtain  36  is preferably provided with a flat and non-inflatable panel  46  that is designed to provide an ejection barrier, but save the time and gas necessary to positively inflate the side air curtain  36  when deployed. 
         [0038]    Further, when a side impact or rollover event occurs, the occupant tends to move toward the vehicle side structure by inertia. However, instead of impacting the A pillar, B pillar, or upper rail of the roof assembly, the occupant&#39;s head and upper thoracic region preferably impacts a side impact airbag that is designed to optimize impacts from the head and/or thoracic regions of the vehicle occupant by being inflated to a relatively soft structure. The de-acceleration experienced by the occupant&#39;s head is thus reduced. Preferably, the region impacted by an occupant&#39;s head and upper thoracic region is less than 20 KPa at about 30 milliseconds after inflation initiation. 
         [0039]    As noted above, however, the relative stiffness of the standard side air curtain  36  renders optimization of a relatively soft impact surface desired for alleviation of side impacts under FMVSS 214 difficult. That is, the pressure within the standard side air curtain  36  at a time period 30 milliseconds after inflation initiation, when contact of the head and thoracic region of the occupant typically occurs, is typically about 60 KPa, even though it is desirable that the region near the vehicle occupant&#39;s head and thoracic region of the side air curtain be at a pressure of less than 20 KPa at 30 milliseconds after actuation of the inflator. 
         [0040]    The side air curtain incorporating the improvement disclosed herein is shown in  FIGS. 3A-3B . As can be seen, the side air curtain  36  forms a relatively flat panel that includes a main inflatable chamber  48  and a separate controlled pressure chamber  50 . The controlled pressure chamber  50  is disposed forward on the flat panel of the side air curtain  36  so that it is adjacent the vehicle occupant situated in the front seat. That is, the controlled pressure chamber  50  is located forward on the side air curtain  36  relative to the vehicle and proximate the front occupant&#39;s head and upper thoracic region. 
         [0041]    As shown in  FIG. 3A , at 20 milliseconds after deployment or ignition of the inflator  38 , the main inflatable chamber  48  of the side air curtain  36  is nearly fully inflated to about 90 KPa, but, as shown, the controlled pressure chamber  50  remains slightly underinflated at 2-3 KPa. In the preferred embodiments, after 30 milliseconds, the pressure in the main inflatable chamber  48  of the side air curtain  36  is overinflated to between 100 and 120 KPa. In contrast, the pressure within the controlled pressure chamber  50  after about 30 milliseconds is at a much lower pressure, preferably less than 20 KPa, and more preferably less than 5 KPa. Thus, the controlled pressure chamber  50  is situated and pressurized to provide the greatest opportunity for mitigation of occupant injuries from a side impact event, while the possibility of subsequent occupant ejection is also reduced. 
         [0042]      FIG. 3B  shows the side air curtain  36  including the present main inflation chamber of the disclosure 50 milliseconds after inflation initiation. As shown, the pressure in the side air curtain  36  has preferably reduced to between 85 and 110 KPa. The pressure in the controlled pressure chamber  50 , however, has been increased in the 20 millisecond interval to preferably between 30 and 60 KPa, depending on pressure regulation, discussed below. In one embodiment, after a period of approximately 65 milliseconds, the pressure in the main chamber of the side air curtain and the controlled pressure chamber  50  becomes equalized at preferably approximately 80 KPa and stays inflated at that pressure for at least 6 seconds, in compliance with FMVSS 226. In another embodiment, the pressure can be equalized at approximately 85 milliseconds at about 80 KPa. 
         [0043]      FIGS. 4 and 5  show the controlled pressure chamber  50 , which is formed as a single integral separate chamber relative the main inflation chamber  48  of the side air curtain  36 . It is comprised of two opposite sheets layers of a flexible air tight material, such as nylon or polyester, as is the remainder of the side air curtain  36 , and is fabricated by either stitching or heat welding about its periphery. The controlled pressure chamber  50  is provided with gaseous fluid from the inflator  38  that is delivered to the main chamber  48  and then allowed to pass through one or more vents  52  provided in a transition panel  54  situated between the main inflation chamber  48  and the controlled pressure chamber  50 .  FIG. 5  shows the controlled pressure chamber  50  with the outer sheet of a portion of the main inflation chamber  48  adjacent the controlled pressure chamber  50  removed to illustrate a pair of gas vents  52  that allow gas to flow from the main inflation chamber  48  into the controlled pressure chamber  50 . 
         [0044]    The rate of inflation of the controlled pressure chamber  50  from main chamber  48  can be controlled through the size, number, and disposition of the gas vent  52  provided between the two chambers in the transition panel  54 . That is, where a larger gas vent  52  is provided or where a plurality of gas vents  52  are provided to create a relatively large combined cross-sectional area, a higher initial pressure within the controlled pressure chamber  50 , with relatively lower peak gas pressure in the main inflation chamber  48 , will be experienced, as depicted in  FIG. 6 . However, in the event that lower initial pressures are desired in the controlled pressure chamber  50 , smaller gas vents  52  or fewer gas vents  52  can be used. Thus, the pressure in the controlled pressure chamber  50  can be adjusted accordingly, so long as the pressure in the controlled pressure chamber  50  is only allowed to a relatively low initial pressure, preferably less than 20 KPa, and more preferably less than 5 KPa. 
         [0045]    Further, the time for pressure equalization can be regulated. For example, as noted above, in a first embodiment of the vent, as shown in  FIG. 6 , a pair of vents  52 , each having a diameter of about 25 millimeters for a larger combined cross-sectional area of about 980 square millimeters can provide pressures that are equalized at approximately 65 milliseconds after inflation initiation to a pressure of about 80 KPa, with pressures in the main inflation chamber  48  of about 110 KPa and the controlled pressure chamber  50  of less than 20 KPa at 30 milliseconds after inflation initiation. In a second embodiment, using a pair of vents  52  each having a diameter of 20 millimeters, for a smaller overall cross-sectional area of about 625 square millimeters, the stabilization time can be extended to roughly 85 milliseconds. With the smaller combined cross-sectional area, pressures may reach about 120 KPa in the main inflation chamber  48  and less than 5 KPa in the controlled pressure chamber  50  at 30 milliseconds after inflation initiation. 
         [0046]    Thus, it can be readily contemplated that the performance of the controlled pressure chamber  50  to provide side impact protection under FMVSS 214 can be adjusted to provide optimal performance by controlling the size and number of the vents  52  in the transition panel  54  provided between the main inflation chamber  48  and the controlled pressure chamber  50  of the side air curtain  36 . Preferably, the vent  52  provides for the main inflation chamber  48  to experience a pressure of at least 110 KPa within 30 milliseconds after actuation of the inflator  38  and approximately 80 KPa within 100 milliseconds after actuation of the inflator  38 . Similarly, the air pressure in the controlled pressure chamber  50  is preferably less than 20 KPa within 30 milliseconds after actuation of the inflator  38 , and more preferably less than 5 KPa, but approximately 80 KPa within 100 milliseconds after actuation of the inflator  38 . 
         [0047]    In accordance with the foregoing disclosure, the need for a second inflator to provide a higher inflation pressure to the main inflation chamber  48  of the side air curtain  36  can be avoided, while simultaneously providing the necessary relative softness to the controlled pressure chamber  50  as the side impact portion of the side air curtain  36  so as to optimize the side impact crash criteria. 
         [0048]    It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.