Abstract:
Reliable and durable tether clips that continue to tether two panels together while allowing for a controlled displacement between the two panels in response to a predetermined force are disclosed. The tether clips according to the present invention include a first retaining means near a first end that is adapted to be securable to a first panel, a second retaining means that is engageable with the second panel and limits the relative separation between the panels, and a releasable fastener means intermediate the first and second retaining means that normally maintains the two panels in a closed configuration relative to one another but that releases at least one of the panels relative to the other panel in response to a predetermined force tending to separate the panels.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of Invention  
           [0002]    This invention relates generally to a panel fastener or clip that normally fastens two panels together but allows for a predetermined displacement between the panels in response to a predetermined force applied to the panels.  
           [0003]    2. Brief Description of the Related Art  
           [0004]    In many applications the need arises to fasten one panel to another. For example, in the automotive industry the interior door panels of the vehicle must be securely fastened to the sheet metal forming part of the vehicle door. Many fasteners for this purpose have been proposed in the art. Examples of such panel fasteners can be seen in U.S. Pat. Nos. 5,758,987 and 6,042,296. However, there remains a need in the art for panel fasteners that, while securing two panels together under normal circumstances, will also allow for a controlled displacement between the two panels in response to the application of a predetermined force. An example, of an application requiring this type of fastener is in cars having side airbags that are concealed by the interior door panels. In such cars, when the side airbag inflates in an accident, the panels must be allowed to be displaced relative to one another to allow the airbag to be deployed properly, however, the panels should not be allowed to become completely disconnected. If an interior panel is allowed to separate completely upon deployment of the airbag, then the loose panel could act as a projectile that can cause injury to a vehicle&#39;s occupants. Furthermore, by limiting the displacement between the panels, reinstallation of the panel subsequent to the deployment of the airbag becomes much easier. The need persists in the art for a reliable and durable panel fastener or clip that will continue to tether two panels together while allowing for a controlled displacement between the two panels in response to a predetermined force.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention is directed to reliable and durable panel fasteners or tether clips that continue to tether two panels together while allowing for a controlled displacement between the two panels in response to a predetermined force. The panel fasteners or tether clips according to the present invention include a first retaining means near a first end that is adapted to be securable to a first panel, a second retaining means that is engageable with the second panel and limits the relative separation between the panels, and a releasable fastener means intermediate the first and second retaining means that normally maintains the two panels in a closed configuration relative to one another but that releases at least one of the panels relative to the other panel in response to a predetermined force tending to separate the panels. The type of panel fasteners that, while securing two panels together under normal circumstances, will also allow for a controlled displacement between the two panels in response to the application of a predetermined force, are referred to herein as tether clips.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    FIGS.  1 - 3  are views of a first embodiment of a tether clip system according to the present invention.  
         [0007]    FIGS.  4 - 8  are views of a second embodiment of a tether clip system according to the present invention. 
     
    
       [0008]    Like reference numerals indicate like elements throughout the several views.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0009]    Referring to FIGS.  1 - 3 , an illustrative example of a tether clip system according to the present invention can be seen. The tether clip system of FIGS.  1 - 3  includes a tether clip  100  for fastening a first panel  102  relative to a second pane  104 . The tether clip  100  comprises a first retaining means  106  adapted to be securable to the first panel  102 ; a second retaining means  108  that is engageable with the second panel  104  and limits the relative separation between the first and second panels; and a releasable fastener means  110  intermediate said first and second retaining means  106  and  108 . The releasable fastener means  110  is adapted to be releasably engageable with the second panel  104 . The releasable fastener means  110  is adapted to normally maintain the first and second panels in a closed configuration relative to one another as shown in FIG. 2. The releasable fastener means  110  is designed to release the second panel  104  in response to a force tending to separate the first and second panels that is greater than a first predetermined value, thus allowing the panel  104  to move to the position shown in FIG. 3.  
         [0010]    The first panel  102  has a first opening  112  and the second panel  104  has a second opening  114 . The first retaining means  106  comprises a shoulder  116 ; a first body portion  118  projecting from a first side of said shoulder  116  and having an end distal from said shoulder  116 . The first body portion  118  has a first longitudinal axis that is coincident with the longitudinal axis of the tether clip  100 . The first retaining means  106  further includes a first pair of resilient snap legs  120  attached to said first body portion  118  proximate said end of said first body portion distal from said shoulder  116 .  
         [0011]    Each of said first pair of resilient snap legs  120  has a proximal end and a distal end. Each of said first pair of resilient snap legs  120  is attached to said first body portion  118  proximate said proximal end of each of said first pair of resilient snap legs. Each of said first pair of resilient snap legs  120  extends from said proximal end thereof generally in a direction toward a plane coincident with said first side  122  of said shoulder  116  and at least in part diverging away from said longitudinal axis of the tether clip  100 .  
         [0012]    Each of said first pair of resilient snap legs  120  has at least one notch  124  provided proximate said distal end of each of said first pair of resilient snap legs  120 . When said first retaining means  106  is secured to the first panel  102 , at least a portion of the first panel  102  proximate the first opening  112  is captured between at least a portion of said shoulder  116  and said notch  124  in each of said first pair of resilient snap legs  120  to thereby secure the tether clip  100  to the first panel  102 .  
         [0013]    The releasable fastener means  110  comprises a second body portion  126  projecting from a second side  128  of said shoulder  116  and has an end distal from said shoulder  116 . The second body portion  126  has a second longitudinal axis in line with said first longitudinal axis and thus coincident with the longitudinal axis of the tether clip  100 . The releasable fastener means  110  further comprises a second pair of resilient snap legs  130  attached to said second body portion  126  proximate said end of said second body portion distal from said shoulder  116 .  
         [0014]    Each of said second pair of resilient snap legs  130  has a proximal end and a distal end. Each of said second pair of resilient snap legs  130  is attached to said second body portion  126  proximate said proximal end of each of said second pair of resilient snap legs  130 , and a portion of each of said second pair of resilient snap legs  130  extends from proximate said proximal end of each of said second pair of resilient snap legs generally in a direction toward a plane coincident with said second side  128  of said shoulder and that diverges away from said longitudinal axis of the tether clip  100 .  
         [0015]    Each of said second pair of resilient snap legs  130  has a surface portion  132  proximate said distal end thereof that converges toward said longitudinal axis of the tether clip with decreasing distance from said second side  128  of said shoulder  116 . When said releasable fastener means  110  is secured to the second panel  104  (as shown in FIGS. 2, 7, and  8 ) at least a portion of the second panel  104  proximate the second opening  114  is captured between at least a portion of said shoulder  116  and said surface portion  132  proximate said distal end of each of said second pair of resilient snap legs  130  to thereby secure the second panel  104  to the first panel  102  in the closed configuration of FIGS. 2, 7, and  8 . The surface portion  132  proximate said distal end of each of said second pair of resilient snap legs  130  cooperates with the portion of the second panel  104  proximate the second opening  114  to bend said second pair of resilient snap legs  130  toward said longitudinal axis of the tether clip to thereby allow the second panel  104  to be released from said releasable fastener means  110  to the positions shown in FIGS. 3, 5 and  6  when said releasable fastener means is initially secured to the second panel  104  and a force tending to move the first and second panels apart and of a magnitude greater than said first predetermined value is applied.  
         [0016]    The said second retaining means  108  comprises a third body portion  138  attached to said releasable fastener means  110  proximate said proximal end of each of said second pair of resilient snap legs  130 . The third body portion  138  has an end distal from said releasable fastener means  110 . The third body portion  138  has a third longitudinal axis in line with said second longitudinal axis and the longitudinal axis of the tether clip  100 . The third body portion  138  has a third pair of resilient snap legs  136  attached to said third body portion  138  proximate said end of said third body portion distal from said releasable fastener means  110 .  
         [0017]    Each of said third pair of resilient snap legs  136  has a proximal end and a distal end. Each of said third pair of resilient snap legs  136  is attached to said third body portion  138  proximate said proximal end of each of said third pair of resilient snap legs  136 . Each of said third pair of resilient snap legs  136  extends from said proximal end thereof generally in a direction toward a plane coinciding with said second side  128  of said shoulder  116  and at least in part diverges away from said longitudinal axis of the tether clip.  
         [0018]    Each of said third pair of resilient snap legs  136  has at least one notch  134  provided proximate said distal end of each of said third pair of resilient snap legs  136 . The notch  134  in each of said third pair of resilient snap legs  136  can engage at least a portion of the second panel  104  proximate the second opening  114  to limit the separation between said first and second panels  102  and  104  when the second panel  104  is released by said releasable fastener means  110  (as shown in FIGS. 3, 5, and  6 ) after being initially secured to the first panel  102  by said releasable fastener means  110 . The snap legs  136  will maintain the panel  104  in the position shown in FIGS. 3, 5, and  6  as long as any applied force tending to move the first and second panels  102  and  104  further apart is of a magnitude less than a second predetermined value.  
         [0019]    In the tether clip  100 , wherein a medial plane passing through both said second pair of resilient snap legs  130  is substantially at a right angle measured about said longitudinal axis of the tether clip  100  relative to a medial plane passing through both said third pair of resilient snap legs  136 .  
         [0020]    The tether clip system of FIGS.  1 - 3  also includes up turned portions  140 . The first pair of regions  140  of said portion of the second panel  104  adjacent said second opening  144  are located on opposite sides of said second opening  114  along a first axis. Each of said first pair of regions  140  at least in part project outward from a first side of the second panel  104  facing the first panel  102  to form a pair of ramped surfaces inclined relative to a medial plane of said portion of the second panel  104  having said second opening  114  therein. The regions  140  present a smooth surface for engagement with the snap legs  130  when the second pair of resilient snap legs  130  engage with the portions of the second panel  104  proximate the second opening  114  to bend said second pair of resilient snap legs  130  toward said longitudinal axis of the tether clip to thereby allow the second panel  104  to be released from said releasable fastener means  110 . This feature provides better control of the force required to release the panel  104  from the releasable fastener means  110  and helps prevent snags.  
         [0021]    The tether clip system of FIGS.  4 - 8  is identical to that of FIGS.  1 - 3  except for the differences noted below. The tether clip system of FIGS.  4 - 8  has a means  142  for increasing retention strength between said second retaining means  108  and the second panel  104  when the second panel has been released from said releasable fastener means  110 .  
         [0022]    In the tether clip system of FIGS.  4 - 8 , the means  142  for increasing retention strength comprises a portion of the second panel  104  having a second opening  114   a  therein. The portion of the second panel  104  surrounding the second opening  114   a  has a first pair of regions  146  that are located on opposite sides of said second opening  114   a  along a first axis. Each of said first pair of regions  146  at least in part project outward from a first side of the second panel  104  facing the first panel  102  to form a pair of ramped surfaces inclined relative to a medial plane of said portion of the second panel  104  having said second opening  114   a  therein. A second pair of regions  144  of said portion of the second panel  104  adjacent said second opening  114   a  are also located on opposite sides of said second opening  114   a , but along a second axis that is perpendicular to said first axis between the regions  146  in plan view. Each of said second pair of regions  144  at least in part project outward from a second side of the second panel opposite the first side of the second panel  104  and provide a catch that more positively engages the snap legs  136  as shown in FIGS. 5 and 6. The means  142  for increasing retention strength comprises the regions  144 .  
         [0023]    As an example of the use of the tether clip  100 , Panel  102  may be the interior panel of the door of a motor vehicle and the panel  104  may be the sheet metal of the door. The retaining means  106  is attached to the panel  102  by pressing in the portion  118  into the hole  112 . The sides of the hole  112  deform the snap legs  120 . Once the notches  124  clear the panel  102 , the snap legs  120  snap open behind the panel  102  to secure the tether clip  100  to the panel  102 . Once the airbag is in place the second retainer  108  is pushed through the hole  114  or  114   a . As with snap legs  120 , snap legs  136  deform by the action of the sides of the hole  114  or  114   a  to allow the snap legs  136  to pass through the hole  114  or  114   a  and open up behind the panel  104  to prevent the tether clip  100  from being pulled completely out of the hole  114  or  114   a  unless a force exceeding the second predetermined force is applied to the panels. The panel  104  can now move freely between the retaining mean  108  and the releasable fastener means  110 . To secure the panel  102  in its normal position, the releasable fastener means  110  is snapped into the hole  114  or  114   a . The snap legs  130  deform by the action of the sides of the hole  114  or  114   a  to allow the snap legs  130  to pass through the hole  114  or  114   a  and open up behind the panel  104  to secure the panel  102  in the normal position of FIGS. 2, 7, and  8 .  
         [0024]    When the airbag inflates, a force in excess of the first predetermined value and tending to pull the panels apart is created. The ramped surfaces  132  catch the edges of the hole  114  or  114   a  in a cam action that bends the snap legs  130  toward the longitudinal axis of the tether clip  100 . This allows the insertion process of the releasable fastener means  110  to be reversed and for the releasable fastener means  110  to release the panel  104 . As the airbag inflates further, the snap legs  136  catch the panel  104  and prevent the panel  102  from being pulled completely free from the vehicle door panel  104 . Thus, an opening between panels  102  and  104  can be provided for the proper inflation of the airbag without allowing the panel  102  to become a projectile. The snap legs  136  are designed such that they fail at forces greater than a second predetermined value that is higher than the forces encountered during airbag deployment. The second predetermined value is usually greater that the first predetermined value. The first predetermined value can range from 10 to 50 lbs., and preferably from about 20 to about 30 lbs., and even more preferably from 20 to 30 lbs. The second predetermined value can be in the range of 75 lbs. and greater, and preferably is in the range of about 150 lbs. and greater, and even more preferably about 150 lbs. The travel between the panels  102  and  104  during airbag deployment is about 25 mm.  
         [0025]    It is to be understood that the present invention is not limited to the embodiments described above, but includes any and all embodiments within the scope of the appended claims. Furthermore, it is to be understood that the embodiments of the present invention disclosed above are susceptible to various modifications, changes and adaptations by those skilled in the art, without departing from the spirit and scope of the invention.