Abstract:
An airbag apparatus for protecting an occupant of a vehicle comprises an inflatable chamber formed by at least one fabric panel and configured to be filled with an inflation gas and deploy into position to protect the occupant; and a tether connected to the panel to restrain deployment of the airbag. During the initial deployment sequence of the airbag, the tether fully extends to a first length. The tether unfolds in order to fully extend to a second length when a sufficient force is applied to the tether by the deploying airbag.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a Continuation-In-Part of U.S. patent application Ser. No. 12/149,347, filed Apr. 30, 2008, which is a Continuation-In-Part of U.S. patent application Ser. No. 11/523,810, filed Sep. 20, 2006, both of which are incorporated herein by reference in their entirety. This application also claims the benefit of and priority to U.S. Provisional Patent Application No. 61/193,111, filed Oct. 29, 2008. The foregoing provisional application is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The present application relates generally to the field of airbags for use within motor vehicles. More specifically, the application relates to a tension tether configured with a delay mechanism used to improve occupant protection by tailoring deployment trajectory of the airbag. 
     The deployment trajectory of an airbag is critical to its effectiveness to provide protection to an occupant during a dynamic impact by a vehicle. Conventional airbag systems have been constructed for the primary purpose to provide protection to in-position occupants. Other conventional airbags have been constructed using active and passive means of occupant detection for the secondary purpose to provide improved protection to an out-of-position (OOP) occupant or a rearward facing infant seat (RFIS). One such construction is constructed with a passive venting system, which allows gas to escape the airbag when it encounters an OOP occupant or a RFIS during deployment to mitigate the impact force, otherwise the passive venting system contains the gas and allows for the cushion to continue expanding to protect an in position occupant. 
     It has been known to provide fixed tethers, both internal and external to the airbag cushion, to aid the trajectory of an airbag during deployment. It has also been known to couple the tether to the airbag or to other vehicle components in providing such support. 
     SUMMARY 
     Based on the foregoing, it is desirable for an airbag apparatus to provide a tailored airbag profile or trajectory that protects both OOP and RFIS during a low risk deployment and also protects in position occupants by providing a standard cushion profile. It would be advantageous to provide this flexible cushion profile in a cost effective and reliable manner. 
     One disclosed embodiment relates to an airbag apparatus for controlling the trajectory of an airbag cushion. The apparatus includes an inflatable chamber formed by at least one fabric panel and configured to be filled with an inflation gas and deploy into position to protect the occupant; and a restraining tab connected to the panel to restrain deployment of the airbag. The restraining tab is configured to separate in a controlled manner when sufficient force is applied to it by the deploying airbag. 
     Another disclosed embodiment relates to an airbag apparatus for protecting an occupant of a vehicle. The apparatus includes an airbag for protecting a vehicle occupant, wherein the airbag is configured to be filled with inflation gas and deploy into a position for protecting the occupant; and a tether connected to the airbag and configured to restrain deployment of the airbag. Prior to deployment of the airbag, the tether is configured to extend to a first length. The tether includes a tear section configured to tear to thereby allow the tether to extend to a second length and wherein the second length is longer than the first length. The tether unfolds when the tear section tears. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below. 
         FIG. 1   a  is a cross sectional side view of an airbag system with a tether. 
         FIG. 1   b  is a top view of an exemplary embodiment of a tether for use in an airbag system. 
         FIG. 1   c  is a top view of the tether shown in  FIG. 1   b.    
         FIG. 1   d  is a cross-section taken along line  1   c  of  FIG. 1   c.    
         FIG. 2   a  is a top view of the tether of  FIG. 1   a , constructed to include a delay mechanism. 
         FIG. 2   b  is a top view of the tether of  FIG. 1   a.    
         FIG. 2   c  is a cross-section taken along line  2   c  of  FIG. 2   b.    
         FIG. 2   d  is a cross-section taken along line  2   d  of  FIG. 2   b.    
         FIG. 3  is a detail view taken from  FIG. 2   a , illustrating the construction of the delay mechanism of the tether. 
         FIG. 4  is a side view of another embodiment of an airbag panel having restraining tabs. 
         FIG. 5  is a detail view taken from  FIG. 5 , illustrating both ends of each restraining tab coupled to the inside of an exemplary airbag panel. 
         FIG. 6  is a side view of a variation of the airbag panel shown in  FIGS. 4-5  having restraining tabs. 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIG. 1   a , the airbag apparatus includes an airbag  15  and a tether  20 . An inflator  2  inflates a chamber of the airbag  15  with inflation gas to deploy the airbag into position to protect an occupant. 
     During deployment of the airbag  15  when an OOP occupant or rear facing child seat is not present, the airbag  15  trajectory may be tailored by the tether  20  by allowing for continued expansion of the airbag  15  until a force is applied to the tether  20 . When a force is applied to the tether  20 , the tether  20  restricts further expansion of the airbag  15  until a predetermined force is reached, whereby the tether  20  tears, allowing the airbag  15  to continue expanding. The force may be a tensile force on the tether. 
     When an OOP occupant or a rear facing child seat is present, the airbag  15  expands until contact occurs between the airbag  15  and the OOP occupant or rear facing child seat, then the airbag  15  remains uniform as the tether  20  is not subjected to the predetermined tension force. 
       FIGS. 1   b - 1   d  show a first embodiment of the tether  20 . The tether  20  includes a first end  21 , a second end  23 , a folded portion  25 , and a region of the tether  20  including a delay mechanism  30 . The tether  20  may be substantially rectangular in shape as shown or some other useful shape. The delay mechanism  30  may include one or more sections of the tether  20  that are designed to tear to allow the tether  20  to unfold and extend in length. These tearable or weakened sections  27  may be integrated into the tether  20  or alternatively be provided as separate strips, bands or pieces of fabric. For example, the weakened sections  27  may be cut out of the tether  20  and may form a rectangular shape as shown. Alternatively, the weakened sections  27  may be constructed in another suitable shape based on the airbag  15  or tether  20  design. For example, the weakened section  27  may be a tapered section having a having a width that is narrower than the first end  21  and the second end  23 . 
     The tether  20  may be coupled to an airbag  15 , internally or externally. In one embodiment, the first end  21  may be coupled to the trailing edge and the second end  23  may be coupled to the leading edge. The trailing edge is the edge or end farthest from the occupant which remains substantially fixed during deployment, of the airbag  15 . The leading edge is the edge or end closest to the occupant which expands toward the occupant during deployment of the airbag  15 . The tether  20  may be made out of any conventional or other useful material. For example, the tether  20  may be made out of nylon 6-6 fabric. 
     In  FIGS. 2   a - 2   d , the exemplary embodiment of the tether  20  of  FIG. 1   a  is shown including a delay mechanism  30 . The delay mechanism  30  may include a folded portion  25 , two creases  26 , the weakened section  27 , a plurality of voids  29 , and a coupling means  31 . There may be multiple folded portions  25 . There may also be more than two creases  26  and weakened sections  27 . 
     The folded portion  25  is constructed by taking the tether  20  and folding the tether  20  into a useful shape, which creates two creases  26 , one on each end of the folded portion  25 . As shown in  FIG. 2   c , the useful shape may be a z-shape fold. Other useful shapes are also possible. The length of the material folded into the folded portion  25  may be tailored to the specific requirements of a vehicle or to control the additional deployment distance following the delay. For example, for different sized passenger compartments, the length of material in the folded portion  25  may be increased or decreased to control proper trajectory of the airbag  15  during airbag  15  deployment. 
     According to one exemplary embodiment, the airbag  15  as shown in  FIGS. 1   a - 2   d  may be modified to tailor its trajectory by providing a series of or sequence of delays in deployment. For example, the tether may include multiple z-shaped folds, each fold being located on top of an adjacent fold and each fold including a delay mechanism  30 . The deployment of the airbag  15  may take place in a series of steps. Each delay mechanism  30  may be configured to release or give way when a specific tensile force is applied to the tether. The weakened section  27  may extend beyond one end of the tether  20  with its base being proximate to one crease  26  and be coupled to the other end of the tether  20  by the coupling means  31 . For example, as shown in  FIG. 2   a , the weakened section  27  may extend beyond the second end  23  of the tether  20  with its base being proximate to one crease  26  and coupled to the second end  21  of the tether  20  by the coupling means  31 . The coupling means  31  may be any conventional method of coupling. For example, the coupling means  31  may be a stitched seam. The portion of the weakened section  27  coupled to the tether  20  does not change position when the tether  20  unfolds. 
     As shown in  FIG. 2   a , the tether  20  may be modified to include a delay mechanism  30  having two weakened sections  27 . In the alternative, the delay mechanism  30  may have one weakened section  27  or more than two weakened sections  27 . The number of weakened sections  27  and the tear strength of each weakened section  27  may be constructed to respond to a specific tension force that is exerted on the tether  20  during the deployment of the airbag  15  in order to tailor deployment of the airbag based on several factors such as, for example, the vehicle, the vehicle seat, mounting location of the airbag, etc. Additionally, other useful shapes may be utilized in constructing the delay mechanism  30  to tailor the deployment and deployment trajectory of the airbag  15 . 
     According to yet another embodiment, a multiple delay system may be constructed that has more than one weakened section  27 . A multiple delay system may include two weakened sections  27 . One of the two weakened sections  27  may be more resistant to tearing than the other weakened section. As a result, the time for the first weakened section to tear will be greater than the time required for the other weakened section to tear. For example, the weakened section  27  may be coupled so that a tension force is not experienced by the section until a tension force applied to the other weakened section causes the shorter weakened section  27  to tear. As the airbag  15  deploys, the expansion of the airbag  15  exerts tension on the first weakened section, delaying further expansion of the airbag  15 , until the first weakened section tears. When the first weakened section  27  tears, the airbag  15  continues expanding until a predetermined tension force is applied to the second weakened section. The second delay occurs as the tension force applied to the second weakened section reaches a predetermined force, whereby the second weakened section tears. When the second weakened section tears, the airbag  15  may continue to deploy. 
     An airbag  15  may be designed with a varying amount of weakened sections  27  to accommodate varying customer requirements or specifications. Meeting the accommodations ensures that optimal protection is provided to an out of position occupant or to a rearward facing child seat. 
       FIG. 3  shows an exemplary embodiment of the delay mechanism  30  of the tether  20 , as previously shown in  FIGS. 2   a - 2   d , in more detail. Each weakened section  27  may be constructed with a plurality of voids  29 , which create tear sections  33 . The tear sections  33  may be a variety of shapes. The shape of the tear section  33  may be dependent on the desired strength of the delay mechanism  30 . When a predetermined force P is applied along the longitudinal axis of the tether  20 , the weakened section  27  tears through the tear sections  33 . The continued application of force P, allows the folded portion  25  of the airbag to unfold, thereby allowing expansion of the airbag  15  to resume. The predetermined force P may be tailored to meet specific requirements of the airbag deployment by controlling the length of the tear sections  33  or by controlling the size and quantity of the voids  29 . The coupling means  31  is configured to be a structural attachment method such as, for example, a stitched seam. Alternatively, the weakened sections  27  may be integrated into the tether. 
     The tear sections  33 , as illustrated in  FIG. 3 , may be designed to tear in varying ways. As shown in  FIG. 3 , a first embodiment of a weakened section  27  includes tear sections  33  which run substantially laterally between a series of voids  29  in a direction generally perpendicular relative to the primary direction of the tensile force applied to the tether. According to a alternative embodiment, also shown in  FIG. 3 , the weakened section  27  may include tear sections  33  which extend between the voids  29  in a generally diagonal direction relative to the direction of the tensile force P applied to the tether. 
     The tether  20  may include a fabric pattern where the weakened section  27  is integrated into the fabric pattern. The fabric pattern or weave pattern may be constructed at an angle to the longitudinal axis of the tether  20 . The angled weave pattern facilitates the tearing of the fibers through tear sections  33  when a predetermined force is applied to the tether  20 , by allowing for initiation and propagation of the tear. The angle may, for example, be a 45 degree angle. Other angles are also possible. 
       FIGS. 4-6  disclose an alternative embodiment of an inflatable airbag  15 . The airbag  15  may include two panels  17  sewn together to form an inflatable chamber. The deployment of the airbag  15  may be restrained by restraining tabs  50 . The restraining tabs  50  may prevent unfolding of the airbag  15  until a predetermined force is applied to the airbag  15  and correspondingly to the retraining tabs  50 . 
     As shown in  FIGS. 4-5 , the first end  55  of the restraining tab  50  may be coupled to the inside of one or both of the airbag panels  17  through a conventional coupling means or mechanism  51  such as, for example, a stitched seam  51 . The restraining tabs may be attached at one or more locations along either or both of the airbag panels  17 . 
     The restraining tabs  50  may each be constructed with a weakened section  53  being narrower in width than the first end  55  and the second end  56  of each restraining tab  50 . Each weakened section  53  may have other shapes. For example, each restraining tab  50  may have a tensile bar, “dog bone” or hourglass shape, where the weakened section  53  is the narrower part of the restraining tab  50 . 
     The tear section  53  may be constructed to tear at a predetermined tensile force applied to the restraining tab  50 , which may be tailored to a specific vehicle or airbag  15  design requirement. During deployment of the airbag  15 , the airbag panel  17  will expand until a force is applied to the restraining tabs  50 . Then deployment of the airbag  15  may be delayed for the required period of time. The delay may be used to provide improved protection to an out of position occupant or a rearward facing child seat, or the delay may provide improved trajectory during deployment to improve protection to an in position occupant. The delay time may be tailored by modifying the geometry, material or material properties of the restraining tab  50 . For example, the thickness, tearing section, or fabric weave orientation of the restraining tab  50  may be altered. 
     The restraining tabs  50  shown in  FIGS. 4-5 , may be constructed so that a tear line through the restraining tab is positioned at a 45 degree angle to the fabric pattern or weave pattern of the restraining tabs  50 . The 45 degree weave pattern facilitates the tearing of the fibers through tear section  53  when a predetermined force is applied to the restraining tab  50 , by allowing for initiation and propagation of the tear. While other embodiments may be constructed using a different weave angle, the 45 degree weave offers good reliability to ensure that a predetermined force or tensile force will induce tearing of the restraining tabs  50 . According to an alternative embodiment, the tear line extends in a direction at a 90 degree angle to the fabric or weave pattern of the restraining tab. The width of the weakened section  53  as well as the overall geometry of the restraining tabs  50  may vary to achieve properties required to accommodate specific customer or vehicle requirements. 
     According to another embodiment, as shown in  FIG. 6 , the restraining tabs  60  may include a plurality of holes  65 , instead of having a weakened section  53  with a width that is narrower than the first section  55  and the second section  56  as shown in  FIGS. 4-5 . The plurality of holes  65  creates a weakened section  63 . The plurality of holes  65  may allow for initiation and propagation of a tear, thereby causing the weakened section  63  to tear. 
     The restraining tabs  60  shown in  FIG. 6 , may be constructed so that a tear line through the restraining tab is positioned at a 90 degree angle to the longitudinal axis of the restraining tabs  60 . The orientation of the tear line relative to the weave pattern facilitates the tearing of the fibers through tear section  63  when a predetermined force is applied to the restraining tab  60 , by allowing for initiation and propagation of the tear. The number and orientation of the holes  65  may be varied along with as the overall geometry of the restraining tabs  60  in order to achieve properties required to accommodate specific vehicle requirements. 
     According to yet another embodiment (not shown), the coupling means may give way to allow deployment of the airbag  15  when a predetermined force is applied to the restraining tabs. The coupling means may be a structural attachment mechanism. 
     As utilized herein, the terms “approximately,” “about,” “substantially”, and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims. 
     It should be noted that the term “exemplary” as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples. 
     The terms “coupled,” “connected,” and the like as used herein means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another. 
     References herein to the positions of elements, for example “top,” “bottom,” “above,” “below,” etc., are merely used to describe the orientation of various elements in the FIGURES. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure. 
     Given the disclosure of the present invention, one versed in the art would appreciate that there may be other embodiments and modifications within the scope and spirit of the invention. Accordingly, all modifications attainable by one versed in the art from the present disclosure within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is to be defined as set forth in the following claims.