Patent Publication Number: US-2006012156-A1

Title: Inflatable curtain with primary and secondary chambers

Description:
FIELD OF THE INVENTION  
      The present invention relates to an inflatable apparatus for helping to protect a vehicle occupant in the event of a side impact to the vehicle and/or a vehicle rollover.  
     BACKGROUND OF THE INVENTION  
      It is known to inflate an inflatable vehicle occupant protection device to help protect a vehicle occupant in the event of a vehicle collision. One particular type of inflatable vehicle occupant protection device is an inflatable curtain that inflates away from the roof of the vehicle downward inside the passenger compartment between a vehicle occupant and the side structure of the vehicle in the event of a side impact or rollover. A known inflatable curtain is inflated from a deflated condition by inflation fluid directed from an inflator to the inflatable curtain.  
     SUMMARY OF THE INVENTION  
      The present invention relates to an apparatus for helping to protect an occupant of a vehicle. The apparatus includes an inflatable curtain that is inflatable away from a vehicle roof of the vehicle to a position between a side structure of the vehicle and a vehicle occupant. The inflatable curtain includes a primary chamber extending from adjacent an upper edge of the inflatable curtain to adjacent a lower edge of the inflatable curtain. A secondary chamber extends from adjacent the upper edge to adjacent the lower edge. At least one passage directs inflation fluid from the primary chamber into the secondary chamber. The passage is spaced from the upper edge and the lower edge. The passage is the only means through which to direct inflation fluid into the secondary chamber.  
      The present invention also relates to an apparatus for helping to protect an occupant of a vehicle that has a side structure and a roof. The apparatus includes an inflatable curtain that is inflatable away from the vehicle roof to a position between the side structure of the vehicle and a vehicle occupant. An inflator provides inflation fluid for inflating the inflatable curtain. The inflatable curtain includes a primary chamber positioned for protecting the occupant&#39;s head in a side impact, a secondary chamber, and at least one passage for directing inflation fluid from the primary chamber into the secondary chamber. The passage is sized to restrict flow into the secondary chamber so that the primary chamber is inflated to at least a predetermined pressure within a predetermined time after actuation of the inflator. The passage is also sized so that the secondary chamber is inflated to at least the predetermined pressure within a predetermined time after the primary chamber is inflated to the predetermined pressure.  
      The present invention further relates to an apparatus for helping to protect an occupant of a vehicle that has a side structure and a roof. The apparatus includes an inflatable curtain that is inflatable away from the vehicle roof to a position between the side structure of the vehicle and a vehicle occupant. An inflation fluid source is actuatable to provide inflation fluid for inflating the inflatable curtain. The inflatable curtain includes a primary chamber, a secondary chamber, and at least one passage for directing inflation fluid from the primary chamber into the secondary chamber. The passage is sized such that the primary chamber is inflated to at least a predetermined pressure within 25 milliseconds after actuation of the inflation fluid source. The passage is also sized such that the secondary chamber is pressurized to at least the predetermined pressure after the primary chamber is pressurized to the predetermined pressure and within 1.5 seconds after actuation of the inflation fluid source. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, in which:  
       FIG. 1  is a schematic view of an apparatus for helping to protect a vehicle occupant illustrating the apparatus in a deflated condition in a vehicle, according to the present invention; and  
       FIG. 2  is a schematic view of the apparatus of  FIG. 1  in an inflated condition in the vehicle.  
    
    
     DESCRIPTION OF AN EMBODIMENT  
      Representative of the present invention, an apparatus  10  helps to protect occupants  100  of a vehicle  12 . As shown in  FIGS. 1 and 2 , the apparatus  10  includes an inflatable vehicle occupant protection device in the form of an inflatable curtain  14  that is mounted adjacent the side structure  16  of the vehicle  12  and the roof  18  of the vehicle. The side structure  16  of the vehicle  12  includes side windows  20 , an A pillar  30 , a B pillar  32 , a C pillar  34 , and a D pillar  36 . Depending on the vehicle, both the C and D pillars could be optional. An inflator  24  is connected in fluid communication with the inflatable curtain  14  through a conduit  22 , such as a fill tube. The fill tube  22  may be constructed of any suitable material, such as metal, plastic, or fabric. Also, those skilled in the art will appreciate that the fill tube  22  may be omitted, in which case the inflator  24  may be connected directly to the inflatable curtain  14 .  
      The fill tube  22  has a first end portion  40  for receiving fluid from the inflator  24 . The fill tube  22  may be connected directly to the inflator  24  or a manifold (not shown) may connect the fill tube to the inflator. The fill tube  22  has a second end portion  42  disposed in the inflatable curtain  14 .  
      The inflator  24  contains a stored quantity of pressurized inflation fluid (not shown) in the form of a gas to inflate the inflatable curtain  14 . The inflator  24  alternatively could contain a combination of pressurized inflation fluid and ignitable material for heating the inflation fluid, or could be a pyrotechnic inflator that uses the combustion of gas-generating material to generate inflation fluid. As a further alternative, the inflator  24  could be of any suitable type or construction for supplying a medium for inflating the inflatable curtain  14 .  
      The apparatus  10  may include a housing  26  ( FIG. 1 ) that stores the inflatable curtain  14  in a stored and deflated condition. The fill tube  22 , the deflated inflatable curtain  14 , and the housing  26  have an elongated configuration and extend along the vehicle roof  18  and along the side structure  16  of the vehicle  12  above the side windows  20 . The fill tube  22 , inflatable curtain  14  and housing  26  are connected to the vehicle  12  by known means  28 , such as brackets.  
      Referring to  FIG. 2 , the inflatable curtain  14  includes panels  50  of material that are arranged in an overlying manner. Portions of the panels  50  are secured together. For example, the panels are secured together along at least a portion of a perimeter  52  of the inflatable curtain  14  to form a perimeter connection  54  of the curtain. The perimeter connection  54  helps define an inflatable volume  56  of the inflatable curtain  14 . The perimeter connection  54  may be formed in a variety of manners, such as by weaving the panels  50  as a single piece of material, stitching the panels together, or interconnecting the panels by ultrasonic welding, heat bonding, or adhesives.  
      The inflatable curtain  14  may also include interior connections  60  in which the overlying panels  50  are secured together within the perimeter  52  of the curtain. The interior connections  60  form non-inflatable portions of the inflatable curtain  14  within the perimeter  52  of the curtain. The interior connections  60  also help define inflatable chambers of the inflatable curtain  14 . These chambers include primary chambers  62  and secondary chambers  64 . The interior connections  60  also help define a central portion  66  of the inflatable curtain  14  and help define chambers  68  of the central portion  66 . The configuration of the interior connections  60 , and thus the chambers  62 ,  64 , and  68 , may vary depending on a variety of factors, such as the architecture of the vehicle  12 , the position of the inflatable curtain  14  in the vehicle, and the desired extent or coverage of the curtain.  
      The panels  50  are woven from a material, such as nylon yarn, and may be coated with a gas impermeable material, such as urethane, or laminated with a gas impermeable film. The inflatable curtain  14  thus may have a substantially gas-tight construction. Those skilled in the art will appreciate that alternative materials, such as polyester yarn, and alternatives coatings, such as silicone, may also be used to construct the inflatable curtain  14 .  
      The inflatable curtain  14  includes an upper edge  70 , an opposite lower edge  72 , and front and rear portions  74  and  76 , respectively, that extend between the upper and lower edges. The front portion  74  includes a front edge  80  formed by the merging upper and lower edges  70  and  72 . In an alternative configuration (not shown), the upper and lower edges  70  and  72  could be spaced from each other and the front edge  80  could extend between them. The front portion  74  includes a non-inflatable sail portion  82  defined by the front edge  80 , the upper and lower edges  70  and  72  and a front connection  84 .  
      The rear portion  76  includes a rear edge  86  of the inflatable curtain  14 . As shown in  FIG. 2 , the rear portion  76  may also include a tab portion  90  for receiving a flexible elongated member  92 , such as a tether, for connecting the rear portion to the vehicle  12 . The perimeter  52  of the inflatable curtain  14  is defined at least partially by the upper edge  70 , lower edge  72 , front edge  80 , and rear edge  86 .  
      The primary chambers  62  and secondary chambers  64  extend generally vertically from adjacent the upper edge  70  to adjacent the lower edge  72  of the inflatable curtain  14 . By “adjacent”, it is meant that the primary and secondary chambers  62  and  64  have upper and lower extents that terminate next to or near the upper and lower edges  70  and  72 , respectively. This is meant to take into account that the perimeter connection  54  and connections  60  may help define the primary chambers  62 , secondary chambers  64 , or both. Thus, for example, in  FIG. 2 , the primary chamber  62  adjacent the front seat occupant  100  has upper and lower extents that terminate at the perimeter connection  54  next to upper and lower edges  70  and  72 , respectively. The secondary chambers  64  adjacent this primary chamber  62  have lower extents that terminate at the perimeter connection  54  next to the lower edge  72  of the inflatable curtain  14 , whereas their upper extents terminate at respective connections  60  near the upper edge  70 .  
      The connections  60  defining the primary chambers  62  are configured such that respective portions  110  of the fill tube  22  are exposed to the primary chambers. This places outlet apertures (not shown) of each portion  110  of the fill tube  22  in direct fluid communication with the primary chamber  62  associated with the respective portion of the fill tube. By “direct fluid communication”, it is meant that inflation fluid from the outlet apertures (not shown) flows into the primary chamber  62  without first flowing into any other chamber.  
      The connections  60  defining the secondary chambers  64  are configured such that the secondary chambers are blocked from direct fluid communication with outlet apertures of the fill tube  22 . This can be achieved, for example, by configuring the connections  60  to block direct fluid communication between the secondary chambers  64  and the outlet apertures of the fill tube  22 , by configuring the fill tube to be free from outlet apertures in direct fluid communication with the secondary chambers, or both. In the illustrated embodiment, the connections  60  that define the secondary chambers  64  also help block direct fluid communication with the outlet apertures in the fill tube  22 .  
      The inflatable curtain  14  includes passages  120  that provide fluid communication between the primary and secondary chambers  62  and  64 . The passages  120  are defined between rounded terminal end portions  122  of certain connections  60  that help define boundaries between the primary and secondary chambers  62  and  64 .  
      The vehicle  12  includes a sensor mechanism  130  (shown schematically in  FIGS. 1 and 2 ) for sensing the occurrence of an event for which occupant protection is desired, such as a side impact to the vehicle  12  and/or a vehicle rollover. Upon sensing the occurrence of such an event, the sensor mechanism  130  provides an electrical signal over lead wires  132  to the inflator  24 . The electrical signal causes the inflator  24  to be actuated in a known manner. The inflator  24  discharges fluid under pressure through fill tube  22 , which directs the fluid into the inflatable curtain  14 .  
      The inflatable curtain  14  inflates under the pressure of the inflation fluid from the inflator  24 . The inflatable curtain  14  inflates away from the roof  18  in a downward direction as shown in the drawings and in a downward direction with respect to the direction of forward travel of the vehicle  12  into the position illustrated in  FIG. 2 .  
      The inflatable curtain  14 , when inflated, extends along the side structure  16  of the vehicle  12  and is positioned between the side structure and any occupant  100  of the vehicle. The inflatable curtain  14  extends between the A pillar  30  and the C pillar  34  of the vehicle  12  and may overlie portions of the A pillar, C pillar, and B pillar  32  of the vehicle.  
      When the inflatable curtain  14  is in the inflated condition of  FIG. 2 , certain ones of the primary chambers  62  are positioned adjacent the occupants  100  of the vehicle  12  and between occupants and the vehicle side structure  16 . Each of these primary chambers  62 , when inflated, covers a portion of the side structure  16  adjacent its respective occupant&#39;s head  102  and a portion of its respective occupant&#39;s torso  104 . The inflatable curtain  14 , when inflated, thus helps to protect the vehicle occupants  100  in the event of a vehicle rollover and/or a side impact to the vehicle  12 . The inflatable curtain  14 , when inflated, helps to absorb the energy of impacts with the curtain and helps to distribute the impact energy over a large area of the curtain.  
      The primary and secondary chambers  62  and  64 , when inflated, expand radially, which causes the inflatable curtain  14  to contract along its length. Since the passages  120  are positioned generally midway between the upper edge  70  and lower edge  72  of the inflatable curtain  14 , the chambers  62  and  64  extend down to adjacent the lower edge of the curtain. As a result, the radial expansion of the chambers  62  and  64  causes the inflatable curtain  14  to contract lengthwise along the lower edge  72 . This helps tension the inflatable curtain  14  along the lower edge  72 .  
      The rate at which inflation fluid flows into the primary chambers can be determined through sizing the inflator  22 , the fill tube  24 , or the apertures (not shown) in the fill tube, or any combination of these three. The size or cross-sectional flow area of the apertures  120  can help determine the rate at which inflation fluid flows into the secondary chambers  64  from the primary chambers  62  and, thus, can help determine the time required to inflate and pressurize the secondary chambers. The apertures  120  can also help determine the time required to inflate and pressurize the primary chambers  62 .  
      Upon actuation of the inflator  24 , inflation fluid flows directly into the primary chambers  62  from the portions  110  of the fill tube  22 . According to the present invention, the passages  120  are configured to help control the timing for the inflation and pressurization of both the primary chambers  62  and the secondary chambers  64 . The passages  120  are sized to choke inflation fluid flow from the primary chambers  62  into the secondary chambers  64 . The degree to which flow into the secondary chambers  64  is choked is determined based on the rate at which inflation fluid is directed into the primary chambers  62 , as dictated by the sizing of the inflator  24 , fill tube  22 , and fill tube apertures (not shown). Knowing the rate at which inflation fluid enters the primary chambers  62  and the volume of the primary chambers, the passages  120  can be sized such that the primary chambers and secondary chambers  64  are inflated and pressurized within a desired time after actuation of the inflator  24 .  
      In the event of a side impact with the vehicle  12 , an occupant&#39;s head  102 , torso  104 , or both are likely to strike the primary chambers  62  of the inflatable curtain  14 . The occupants  100  may also strike the secondary chambers  64 . In a scenario involving normally seated occupants, such as that illustrated in  FIGS. 1 and 2 , the occupants will most likely strike the primary chambers  62  first. Therefore, in the event of a side impact with the vehicle  12 , such might occur if the vehicle struck a pole or another vehicle, it may be desirable to inflate and pressurize the primary chambers  62  to a predetermined minimum pressure before the secondary chambers  64  are inflated and pressurized to the predetermined minimum pressure. This predetermined minimum pressure may, for example, be a minimum pressure required to prevent strikethrough in the primary chamber  62 , i.e., a minimum pressure required to prevent an occupant&#39;s head having a given mass from striking the side structure  16  through the inflated primary chamber when traveling at a given velocity. It will thus be appreciated that the predetermined minimum pressure may vary depending on a variety of factors, such as the inflated thickness of the primary chambers  62  and the desired criteria for strikethrough prevention.  
      In a rollover scenario of the vehicle  12 , the inflatable curtain  14  serves the additional purpose of helping prevent the occupants  100  or portions of the occupants, such as limbs, from exiting the vehicle, for example, through the window openings  20 . The inflatable curtain  14  is suited for this purpose because it is tensioned along its length and along the vehicle side structure  16 . In the event of a pure rollover scenario, such as a rollover that results from a lateral skid of the vehicle  12  (with no side impact), the rollover evolves over a period of time greater than that over which a side impact evolves. Therefore, in the pure rollover scenario, the time within which the inflatable curtain  14  is inflated and deployed may be greater than that required for a side impact scenario. If, however, a vehicle impact, such as a side impact or an offset impact, occurs or is otherwise is involved in a rollover scenario, quicker inflation and pressurization of the primary chambers  62  may be required.  
      In view of the foregoing, those skilled in the art will appreciate that rapid inflation and pressurization of the primary chambers  62  is desirable in both a side impact and a vehicle rollover. According to the present invention, the passages  120  are configured such that the primary chambers  62  are inflated and pressurized before the secondary chambers  64 . The time within which the primary chambers  62  are inflated and pressurized may depend on a variety of factors, such as the architecture of the vehicle  12  and the configuration of the inflatable curtain  14 . For example, for the inflatable curtain  14  of  FIGS. 1 and 2 , the passages  120  may be configured such that the primary chambers  62  are inflated and pressurized within 25 milliseconds after actuation of the inflator  24 .  
      The passages  120  are also configured such that the secondary chambers  64  are pressurized after the primary chambers  62  are pressurized. Inflation of the secondary chambers  64  may begin shortly after inflation of the primary chambers  62  begins and before the primary chambers are pressurized to the predetermined minimum pressure. The time within which the secondary chambers  64  are inflated and pressurized to the predetermined minimum pressure may depend on a variety of factors, such as the architecture of the vehicle  12  and the configuration of the inflatable curtain  14 . For example, for the inflatable curtain of  FIGS. 1 and 2 , the passages  120  may be configured such that the secondary chambers  64  are inflated and pressurized to the predetermined minimum pressure within 1.5 seconds after actuation of the inflator  24 . It will be appreciated, however, that the secondary chambers  64  may be inflated and pressurized to the predetermined minimum pressure more rapidly, such as within 50 milliseconds after actuation of the inflator  24 .  
      The desired pressure to which the chambers  62 ,  64 , and  68  are inflated may depend on a variety of factors, such as the inflated thickness of the curtain. For example, the desired pressure may be at least 5 psi. Thus, in the example set forth above, for the inflatable curtain  14  of  FIGS. 1 and 2 , the primary chambers  62  would be inflated to at least 5 psi within 25 milliseconds after actuation of the inflator  24 . The secondary chambers  64  would be inflated to at least 5 psi after the primary chamber  62  is pressurized and within 1.5 seconds after actuation of the inflator  24 .  
      From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. For example, the connections  60 , the fill tube  22 , or both could be re-configured such that the rearwardmost chamber of the inflatable curtain  14  in  FIG. 2  is a secondary chamber  64 . In this configuration, inflation fluid would be directed into this rearwardmost secondary chamber  64  only through the passage  120  from the adjacent primary chamber  62 . The primary chamber  62  and secondary chamber  64  would be inflated and pressurized in a manner similar or identical to that described above with regard to the other primary and secondary chambers of the curtain. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.