Abstract:
An inflatable curtain for protecting the occupants of a vehicle during a collision is provided. The inflatable curtain may include an inflatable portion. The inflatable portion may include a plurality of inflation chambers. The inflatable curtain may also include a non-inflatable portion. The non-inflatable portion may include one or more expandable sections disposed between adjacent inflation chambers. Deployment of the inflatable curtain typically causes the inflation chambers to contract in a horizontal direction. Deployment of the inflatable curtain also causes each of the expandable sections to expand horizontally, compensating for the contraction that occurs in the inflation chambers.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an inflatable curtain designed to protect the occupants of a vehicle during a side impact collision. More specifically, the invention relates to an expandable section in an inflatable curtain that compensates for horizontal contraction of the inflatable curtain during deployment. 
     2. Description of Related Art 
     In low-speed automobile collisions, occupants wearing safety belts are generally prevented from impact with the car&#39;s interior objects, such as the windshield, instrument panel, or steering wheel. In more severe collisions, however, even belted occupants may impact the car&#39;s interior objects because their forward motion is so great that they contact these objects before the belts can bring them to a complete stop. 
     Vehicle manufacturers and suppliers have developed air bag systems, including side impact air bag systems, to supplement safety belts by reducing the chances of contact with the vehicle&#39;s interior objects. In addition, to the extent that such contact cannot be prevented, air bag systems have been designed to distribute the impact more evenly over an occupant&#39;s head and torso. 
     A side impact air bag system typically consists of three parts: an inflatable curtain, an inflator, and a sensor mechanism. The inflatable curtain is typically made of a thin nylon fabric, and may be compacted by accordion folding, rolling, or any other suitable method, and mounted within a housing located in the vehicle over the doors. The inflatable curtain is typically in communication with the inflator, which is typically in communication with the sensor mechanism. A chemical compound and/or compressed gas may be sealed inside the inflator. After impact of sufficient severity, the sensor mechanism detects the sudden deceleration and sends an electrical signal to the inflator. The inflator then produces gas which inflates the inflatable curtain. As an occupant contacts the inflatable curtain, the gas is vented through openings in the sides of the inflatable curtain, thus absorbing the motion of the occupant&#39;s impact. 
     An inflatable curtain typically includes an inflatable portion, which may include one or more inflation chambers. An inflatable curtain typically also includes a non-inflatable portion. Adjacent inflation chambers are typically separated by part of the non-inflatable portion. Deployment of the inflatable curtain typically causes the inflation chambers to contract in a horizontal direction. Contraction of the inflation chambers during deployment may cause the inflation chambers to move out of position, thereby reducing the amount of protection that can be provided to a vehicle occupant during a collision. 
     One known solution to this problem involves cutting away the non-inflatable portion of the inflatable curtain between adjacent inflation chambers, thereby creating an opening. A connection fabric is then attached to the inflatable curtain inside the opening. The connection fabric has a length that is greater than the length of the opening. This allows the connection fabric to expand during deployment, thereby compensating for the contraction that occurs during deployment. This approach, however, requires that a certain amount of fabric be wasted (i.e., the part of the non-inflatable portion that is cut away), which can be expensive in terms of both material costs and labor. This approach also requires that the connection fabric be slack prior to deployment, which can make it difficult to compact the inflatable curtain in order to store it in the vehicle. 
     Accordingly, it would be an advancement in the art to provide a way to compensate for contraction that occurs in an inflatable curtain during deployment without requiring that a certain amount of fabric be wasted, and without adding to the complexity involved in storing the inflatable curtain in the vehicle prior to deployment. The present invention provides these advancements in a novel and useful way. 
     SUMMARY OF THE INVENTION 
     The apparatus of the present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available inflatable curtains. In accordance with the invention as embodied and broadly described herein, an inflatable curtain for protecting the occupants of a vehicle during a collision is provided. 
     According to one configuration, the inflatable curtain may include an inflatable portion. The inflatable portion may include a plurality of inflation chambers. The length of each inflation chamber will be referred to herein as a span length. The distance between adjacent inflation chambers will be referred to herein as a separation length. The inflatable portion may also include an inflation inlet for communication with an inflator. 
     The inflatable curtain may also include a non-inflatable portion. The non-inflatable portion may include one or more expandable sections disposed between adjacent inflation chambers. 
     Deployment of the inflatable curtain typically causes the inflation chambers to contract in a horizontal direction. Thus, the span length of each inflation chamber typically decreases during deployment. Advantageously, deployment of the inflatable curtain also causes each of the expandable sections to expand horizontally. Thus, the separation length between adjacent inflation chambers increases during deployment, compensating for the contraction that occurs in the inflation chambers. In one embodiment, the expandable sections may be configured so that the total length of the inflatable curtain remains substantially unchanged during deployment. 
     An expandable section may include a pleat that unfolds during deployment of the inflatable curtain. In one embodiment, an expandable section may include two layers, a first layer and a second layer. The first layer may include a first slit and a first edge adjacent the first slit. Similarly, the second layer may include a second slit and a second edge adjacent the second slit. The pleat may be formed by folding the second layer so that the second edge is aligned with the first edge. 
     In such an embodiment, a secure fastening mechanism may be provided to fasten the first edge to the second edge. The secure fastening mechanism may cause the first edge to remain fastened to the second edge after deployment of the inflatable curtain. The secure fastening mechanism may take the form of an attachment seam sewn through the first edge and the second edge. 
     In addition, a severable fastening mechanism may be provided which causes the pleat to remain folded prior to deployment of the inflatable curtain and which allows the pleat to unfold during deployment of the inflatable curtain. The severable fastening mechanism may take the form of a tear seam sewn through the pleat. 
     These and other features and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the manner in which the above-recited and other features and advantages of the invention are obtained will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
     FIG. 1 is a side plan view of an embodiment of an inflatable curtain; 
     FIG. 2 is a perspective of the inflatable curtain of FIG. 1 installed in a vehicle and shown in its stored position prior to deployment; 
     FIG. 3 is a side plan view of an expandable section of the inflatable curtain during formation of a pleat; 
     FIG. 4 is a side plan view of an expandable section of the inflatable curtain during formation of a pleat; 
     FIG. 5 is a side plan view of an expandable section of the inflatable curtain during formation of a pleat; 
     FIG. 6 is a side plan view of an expandable section of the inflatable curtain during formation of a pleat; and 
     FIG. 7 is a side plan view of the inflatable curtain of FIG. 1 installed in a vehicle and shown after deployment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The presently preferred embodiments of the present invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the present invention, as represented in FIGS. 1 through 7, is not intended to limit the scope of the invention, as claimed, but is merely representative of presently preferred embodiments of the invention. 
     FIG. 1 is a side plan view of an embodiment of an inflatable curtain  100 . The inflatable curtain  100  is configured to be mounted within a vehicle over its doors. The inflatable curtain  100  may become deployed during an accident to cover the windows, doors, and lateral surfaces of a vehicle. The front side  110  of the inflatable curtain  100  is shown in FIG.  1 . 
     The inflatable curtain  100  includes an inflatable portion  112 . The inflatable portion  112  includes a plurality of inflation chambers  114   a-c.  Each inflation chamber  114  includes a plurality of inflatable cells  116 . The inflatable portion  112  also includes an inflation inlet  118  that is configured to be in communication with an inflator (not shown). The inflator may be of any suitable type or construction for supplying a medium for inflating the inflatable portion  112  of the inflatable curtain  100 . 
     The inflatable curtain  100  also includes a non-inflatable portion  120 . The non-inflatable portion  120  is sealed off from the inflatable portion  112  so that inflation of the inflatable portion  112  does not cause the non-inflatable portion  120  to inflate. The non-inflatable portion  120  includes an upper edge  122 . A plurality of vertical protrusions  124  extend from the upper edge  122 . Each of the vertical protrusions  124  includes an opening  126 . The vertical protrusions  124  may be used to attach the inflatable curtain  100  to a vehicle. Specifically, a suitable fastener (e.g., screw, bolt, etc.) may be inserted through the openings  126  and through a portion of a vehicle frame to attach the inflatable curtain  100  to a vehicle. 
     The non-inflatable portion  120  also includes an expandable section  128  between adjacent inflation chambers  114 . In general terms, the expandable sections  128  expand during deployment of the inflatable curtain  100  in order to compensate for contraction that occurs in the inflation chambers  114  as they inflate. A boundary  130  divides each expandable section  128  from the rest of the non-inflatable portion  120 . The boundary  130  may be a seam  130 . 
     As shown in FIG. 1, each expandable section  128  includes a pleat  132 . A severable fastening mechanism  134  holds the pleat  132  in place prior to deployment of the inflatable curtain  100 . As the inflatable curtain  100  deploys, the severable fastening mechanism  134  breaks, causing the pleat  132  to unfold. Unfolding of the pleat  132  allows the expandable section  128  to expand. 
     The severable fastening mechanism  134  may take the form of a tear seam  134  sewn through the pleat  132 . As used herein, a tear seam  134  refers to a seam that is sufficiently strong to hold the pleat  132  in place prior to deployment of the inflatable curtain  100 , and that is sufficiently weak to break during deployment of the inflatable curtain  100 . Factors that may affect the strength of a seam include the weight of thread used to make the seam, and the stitching frequency (i.e., the number of stitches per unit length). In one embodiment, the tear seam  134  is sewn using T-16 or T-25 thread, and at a stitching frequency of 18-20 stitches per 100 mm of length. 
     As shown in FIG. 1, each expandable section  128  includes two layers of fabric, a first layer  136  and a second layer (not shown in FIG.  1 ). The two layers of fabric may be formed from a one-piece weaving technique, in which a single piece of fabric is woven so as to create two distinct layers. Alternatively, the two layers of fabric may be formed from two separate pieces of fabric. 
     The first layer  136  includes a first slit  138 . A first edge  140  is adjacent and interior to the first slit  138 . A second slit (not shown in FIG. 1) is cut in the second layer. A second edge (not shown in FIG. 1) is adjacent and interior to the second slit. The first slit  138  and the second slit are used to form the pleat  132 . In general terms, this is accomplished by folding the second layer so that the second edge is aligned with the first edge  140 . A more detailed explanation of how the first slit  138  and the second slit may be used to form the pleat  132  will be provided below in connection with FIGS. 3-6. 
     A secure fastening mechanism  142  fastens the first edge  140  to the second edge. The secure fastening mechanism  142  causes the first edge  140  to remain fastened to the second edge after deployment of the inflatable curtain  100 . The secure fastening mechanism  142  may take the form of an attachment seam  142  sewn through the first edge  140  and the second edge. As used herein, an attachment seam  142  refers to a seam that is sufficiently strong to remain in place during deployment of the inflatable curtain  100 . Typically, a heavier thread is used to sew the attachment seam  142  than the tear seam  134 . Also, the attachment seam  142  is typically sewn with a higher stitching frequency than the tear seam  134 . In one embodiment, the attachment seam  142  is sewn using 96-132 weight thread, and at a stitching frequency of 30-40 stitches per 100 mm of length. 
     The inflatable curtain  100  has a total length  146 . The total length  146  of the inflatable curtain  100  is influenced by the length of each inflation chamber  114 . The length of a single inflation chamber  114  will be referred to herein as a span length  150 . There are three inflation chambers  114  shown in FIG.  7 : a first inflation chamber  114   a,  a second inflation chamber  114   b,  and a third inflation chamber  114   c.  The first inflation chamber  114   a  has a first span length  150   a,  the second inflation chamber  114   b  has a second span length  150   b,  and the third inflation chamber  114   c  has a third span length  150   c.    
     The total length  146  of the inflatable curtain  100  is also influenced by the distance between two adjacent inflation chambers  114 , which will be referred to herein as a separation length  148 . The first and second inflation chambers  114   a,    114   b  are separated by a first separation length  148   a.  The second and third inflation chambers  114   b,    114   c  are separated by a second separation length  148   b.    
     FIG. 2 is a perspective view of the inflatable curtain  100  of FIG. 1 installed in a vehicle  200  and shown in its stored position prior to deployment. The vehicle  200  includes a side portion  210 , with a front window  212  and a rear window  214  positioned on the side portion  210 . A front door  216  is positioned beneath the front window  212 , and a rear door  218  is positioned beneath the rear window  214 . A front seat  220  is positioned adjacent to the front door  216 , and a rear seat  222  is positioned adjacent to the rear door  218 . A steering wheel  224  is positioned in front of the front seat  220 . 
     An A-pillar  226  is provided toward the front part of the front door  216 . A B-pillar  228  is provided between the front window  212  and the rear window  214 . A C-pillar  230  is provided toward the rear part of the rear door  218 . A roof  232  is positioned over the top of the vehicle  200 . 
     A housing  234  defines an internal recess that accommodates the inflatable curtain  100  in the vehicle  200  prior to inflation. The housing  234  has a non-linear, elongated configuration, originating at a point on the C-pillar  230  and extending along the roof  232 . The inflatable curtain  100  may be compacted by accordion folding, rolling, or any other suitable method and stored in the housing prior to inflation. A plurality of fasteners  236  may be located on the housing  234  and used to secure the housing  234  to the vehicle  200 . 
     The vehicle  200  also includes a sensor mechanism  238 , which is adapted to sense a side impact to the vehicle. Lead wires  240  are attached to the sensor mechanism  238 . The lead wires  240  provide electrical communication between the sensor mechanism  238  and an inflator (not shown in FIG. 2) which is in communication with the inflatable curtain  100 . 
     FIGS. 3-6 illustrate one way in which the pleat  132  illustrated in FIG. 1 may be formed in an expandable section  128 . FIGS. 3-6 are arranged so as to illustrate successive steps in the formation of the pleat  132 . Of course, the steps illustrated in FIGS. 3-6 are intended to be illustrative, not restrictive. Those skilled in the art will recognize a variety of different ways in which the pleat  132  may be formed. 
     FIG. 3 is a side plan view of an expandable section  128  of the inflatable curtain  100  during formation of a pleat  132 . Specifically, FIG. 3 illustrates the front side  110  of the inflatable curtain  100  and the first layer  136  of an expandable section  128 . As shown in FIG. 3, formation of a pleat  132  may involve cutting a first slit  138  in the first layer  136  of an expandable section  128 . As stated previously, a first edge  140  may be located adjacent and interior to the first slit  138 . 
     FIG. 4 is a side plan view of an expandable section  128  of the inflatable curtain  100  during formation of a pleat  132 . Specifically, FIG. 4 illustrates the back side  410  of the inflatable curtain  100  and the second layer  412  of the expandable section  128 . As shown in FIG. 4, formation of a pleat  132  may involve cutting a second slit  414  in the second layer  412  of the expandable section  128 . A second edge  416  may be located adjacent and interior to the second slit  414 . Cutting the second slit  414  causes there to be a flap portion  418  in the second layer  412 . 
     FIG. 5 is a side plan view of an expandable section  128  of the inflatable curtain  100  during formation of a pleat  132 . Specifically, FIG. 5 illustrates the back side  410  of the inflatable curtain  100  after a second slit  414  has been cut in the second layer  412 . As shown in FIG. 5, formation of a pleat  132  may involve folding the flap portion  418  of the second layer  412  so that the second edge  416  is aligned with the first edge  140  of the first layer  136 . The flap portion  418  may be folded under the rest of the second layer  412  so that the second edge  416  touches the first edge  140 . 
     FIG. 6 is a side plan view of an expandable section  128  of the inflatable curtain  100  during formation of a pleat  132 . Specifically, FIG. 6 illustrates the front side  110  of the inflatable curtain  100  after the flap portion  418  of the second layer  412  has been folded under the rest of the second layer  412 . As shown in FIG. 6, formation of a pleat  132  may involve providing a secure fastening mechanism  142  that fastens the first edge  140  to the second edge  416  and that causes the first edge  140  to remain fastened to the second edge  416  after deployment of the inflatable curtain  100 . As described previously, the secure fastening mechanism  142  may take the form of an attachment seam  142 . Formation of a pleat  132  may also involve providing a severable fastening mechanism  134  that causes the pleat  132  to remain folded prior to deployment of the inflatable curtain  100  but that allows the pleat  132  to unfold during deployment of the inflatable curtain  100 . As described previously, the severable fastening mechanism  134  may take the form of a tear seam  134 . 
     FIG. 7 is a side plan view of the inflatable curtain  100  of FIG. 1 installed in a vehicle  200  and shown after deployment. The housing  234  is in an open position, so that the inflatable curtain  100  is not contained within the housing  234 . An inflator  710  is shown in communication with the inflation inlet  118 . The inflator  710  includes lead wires  712  that are in electronic communication with the lead wires  240  attached to the sensor mechanism  238 . The inflator  710  has discharged, and the inflatable curtain  100  is shown in its inflated position, located between the front seat  220  and rear seat  222  and the side portion  210  of the vehicle  200 . 
     Deployment of the inflatable curtain  100  has caused the inflation chambers  114  to contract. That is, the first inflation chamber  114   a  has a span length  750   a  after deployment that is less than its span length  150   a  prior to deployment, the second inflation chamber  114   b  has a span length  750   b  after deployment that is less than its span length  150   b  prior to deployment, and the third inflation chamber  114   c  has a span length  750   c  after deployment that is less than its span length  150   c  prior to deployment. 
     Deployment of the inflatable curtain  100  has also caused the expandable sections  128  to expand. In the embodiment shown in FIG. 7, deployment of the inflatable curtain  100  has caused the severable fastening mechanisms  134  to break, allowing the pleats  132  to unfold and causing the expandable sections  128  to expand. Expansion of the expandable sections  128  increases the separation length  748  between adjacent inflation chambers  114 . That is, the separation length  748   a  between the first inflation chamber  114   a  and the second inflation chamber  114   b  after deployment is greater than the separation length  148   a  between the first inflation chamber  114   a  and the second inflation chamber  114   b  prior to deployment. Similarly, the separation length  748   b  between the second inflation chamber  114   b  and the third inflation chamber  114   c  after deployment is greater than the separation length  148   b  between the second inflation chamber  114   b  and the third inflation chamber  114   c  prior to deployment. 
     The expandable section  128  may be configured so that the expansion of the expandable sections  128  compensates for the contraction of the inflation chambers  114  during deployment. In this way, the total length  146  of the inflatable curtain  100  may remain substantially unchanged during deployment. In the embodiment shown in FIG. 7, the expansion of the expandable sections  128  is proportional to the size of the pleat  132 . Thus, the amount of expansion that occurs in the expandable sections  128  during deployment may be adjusted by adjusting the size of the pleat  132 . 
     The present invention may be embodied in other specific forms without departing from its structures, methods, or other essential characteristics as broadly described herein and claimed hereinafter. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.