Abstract:
A motor vehicle has a sliding door supported by front and rear roller brackets that move through corresponding roller tracks. By extending the length of the rear roller track supporting the sliding door to beyond the rear end of the vehicle when the sliding door itself is opened beyond a particular location, a larger door and door opening are possible for any particular vehicle size. This provides better occupant access to rear seats and increases the maximum cargo size that can be loaded through the door opening.

Description:
BACKGROUND OF INVENTION 
       [0001]    The present invention relates generally to vehicular sliding doors in which the rearward side of the sliding door is supported by a roller bracket that traverses a roller track mounted along the exterior side of the vehicle. 
         [0002]    A typical sliding door for a passenger vehicle such as a van, minivan, or a crossover vehicle is supported and guided by upper and lower roller bracket assemblies at the front edge of the sliding door and a center roller bracket assembly attached to the rear edge of the door. The size of the door opening that may be uncovered when the sliding door opens is limited in the prior art to the available distance of rearward travel for the door. A large door opening is desired for ease of ingress/egress and for maximizing the size of loads that may pass through the door opening. However, door travel is typically limited by the length of the tracks in which the roller bracket assemblies traverse during opening of the sliding door. The center track which receives a roller bracket mounted to the rearward edge of the sliding door has not been able to extend beyond the back edge of the vehicle body. Therefore, the open door space for ingress/egress in prior art vehicles has been undesirably limited. 
       SUMMARY OF INVENTION 
       [0003]    By extending the length of the rear roller track supporting a sliding door to beyond the rear end of the vehicle when the sliding door itself is opened beyond a particular location, a larger door and door opening are possible for any particular vehicle size. This provides better occupant access to rear seats and increases the maximum cargo size that can be loaded through the door opening. 
         [0004]    In one preferred aspect of the invention, a sliding door system for a vehicle has a sliding door that slides from a door opening toward a rear end of the vehicle. A roller bracket has a hinged connection at one end for coupling to the sliding door and has orthogonal rollers at the other end. A fixed primary track mounts to a side of the vehicle and extends away from the door opening to a terminus. The primary track has a generally C-shaped cross section with a first vertical load portion and a first horizontal load portion. The first load portions receive the orthogonal rollers. A concentric track bracket mounts to the side of the vehicle and has at least a portion disposed between the terminus of the primary track and the rear end of the vehicle. The concentric track bracket has a generally C-shaped cross section greater than and substantially coaxial with the primary track. A track extension has a first end and an interlock end, the track extension being slidably received in the concentric track bracket between a retracted position and an extended position. The track extension is locked in coaxial abutment with the terminus when in the retracted position. The interlock end extends past the rear end of the vehicle when in the extended position. The track extension has a generally C-shaped cross section with a second vertical load portion and a second horizontal load portion, the second load portions aligned with the first load portions, respectively, for receiving the orthogonal rollers when the roller bracket moves from the primary track to the track extension. When the roller bracket moves in an opening direction from the primary track into the track extension and then to the interlock end, the track extension remains in the retracted position. When the orthogonal rollers enter the interlock end then they are captured and the track extension is released to slide within the concentric track to the extended position. When the track extension returns from the extended position to the retracted position then the orthogonal rollers are released from the interlock end, thereby enabling the roller bracket to slide through the track extension and back into the primary track. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0005]      FIG. 1  is a perspective view showing a vehicle with a sliding door in the closed position. 
           [0006]      FIG. 2  is a diagram showing the relationship between door opening size and sliding door travel for a vehicle body having a particular length. 
           [0007]      FIG. 3  is an end view of a track system with a roller bracket received in the track extension. 
           [0008]      FIG. 4  is a front plan view showing a track extension in the retracted position. 
           [0009]      FIG. 5  is a front plan view of a track extension in an extended position. 
           [0010]      FIGS. 6-10  are front plan views showing a roller interacting with an interlock on the track extension. 
           [0011]      FIG. 11  is an end view showing the embodiment of  FIGS. 6-10 . 
           [0012]      FIG. 12  is a top view showing the interlock system of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Referring now to  FIG. 1 , a vehicle  10  has a sliding door  11  supported along an upper roller track  12 , a lower roller track  13 , and a center roller track  14 . Respective roller brackets (not shown) slidable in each track are joined to respective door brackets (not shown) on the interior side of sliding door  11 . In a conventional system, a pair of brackets at the top and bottom of the forward edge of sliding door  11  is joined to the roller brackets sliding in tracks  12  and  13 , respectively. A door bracket attached at the center rear edge of sliding door  11  is coupled to a roller bracket slidably received in track  14 . The tracks have initial portions which move radially outward so that the door first moves outward from the vehicle body in order to clear the vehicle body and then slides toward the rear of vehicle  10 . Because of this compound movement, each roller bracket is pivotally connected to its respective door bracket. 
         [0014]    Sliding door  11  and the opening in vehicle  10  which receives sliding door  11  each have a front-to-back width designated D 1 . For conventional sliding doors, the rearward movement of sliding door  11  has a maximum distance designated D 2  which is the length of center track  14  from the edge of the door opening to the end of track  14 . The space available for track  14  is limited by the overall length of vehicle  10 . If distance D 2  is less than distance D 1 , then when a conventional sliding door  11  is at its maximum rearward travel position it continues to block a portion of the door opening. It would be desirable to obtain an extension of the sliding door travel. 
         [0015]    As shown in  FIG. 2 , vehicle  10  may have a side passenger opening  16  allowing ingress to and egress from seats  17 . In the upper half of  FIG. 2 , opening  16  is sufficiently small compared to the length of the vehicle behind opening  16  that a center track  18  can be accommodated on vehicle  10  to allow opening of the sliding door to a position  19  using conventional door sliders. In the lower half of  FIG. 2 , a larger (i.e., wider) opening  16 ′ allows easier ingress and egress to rear seat  17 . However, the remaining length of the vehicle for accommodating a longer track is insufficient. Therefore, the sliding door cannot be moved to a desired position  19 ′ using the conventional sliding door support apparatus. Therefore, in addition to a primary track  20 , the present invention employs a track extension  21  that slides rearward beyond the rear end of the vehicle at the appropriate times so that the door is supported over a greater range of movement. 
         [0016]      FIG. 3  shows the main elements of the invention including a track extension  21  slidably retained inside a concentric track bracket  22  by means of sliders  23  and  24 . A roller bracket  25  is attached to a sliding door  26  via a door bracket  27  and hinge pin  28 . Roller bracket  25  has orthogonal rollers  30  and  31  as is known in the art. Track extension  21  has a generally C-shaped cross section with a horizontal load portion  32  for containing roller  30  and a vertical load portion  33  for supporting roller  31 . Concentric track bracket  22  has a similar but slightly larger C-shaped cross section for nestingly receiving track extension  21 . Concentric track bracket  22  is fixedly mounted to the side of the vehicle  34 . 
         [0017]    The tracks and track bracket are shown in greater detail in  FIGS. 4 and 5 . Concentric track bracket  22  preferably nestingly receives both primary track  20  and track extension  21 . Primary track  20  is also fixedly mounted to the side of the vehicle and extends away from the door opening to a terminus  36 . Primary track  20  has the same generally C-shaped cross section with a vertical load portion and horizontal load portion as discussed for track extension  21 . When track extension  21  is in its retracted position as shown in  FIG. 4 , it is locked in coaxial abutment with terminus  36  so that the orthogonal rollers can freely move between primary track  20  and track extension  21 . Track extension  21  has a first end  37  and an interlock end  38  to receive an interlock (described below) that prevents the roller bracket from sliding off the end of track extension  21 . In order to prevent track extension  21  from sliding off the end of concentric track bracket  22 , a stop feature  40  is provided on track extension  21  and a stop feature  41  is provided on concentric track bracket  22  for interfering with one another when track extension  21  reaches its maximum extended position, thereby preventing further movement in the rearward direction of track extension  21 . Stops  40  and  41  may preferably comprise an indent and an outdent which are stamped into the respective sheet metal components. A shock absorbing rubber bumper may be provided on the stop features to prevent the user from experience shock or noise at the end of the door travel. 
         [0018]      FIGS. 6-10  show the detailed functioning of the present invention. During the door opening process, roller bracket  25  first traverses primary track  20  beginning at the door opening. Roller bracket  25  moves in the opening direction from primary track  20  into track extension  21  and to interlock end  38  while extension track  21  remains locked in the retracted position. When the orthogonal rollers (or, alternatively, some other activating portion of roller bracket  25 ) enters interlock end  38  then the rollers or other feature are captured at the interlock end and track extension  21  is released within concentric track bracket  22  to slide to the extended position. During the door closing process, an occupant pulls the door in the closing direction so that track extension  21  returns from the extended position to the retracted position. Then the orthogonal rollers are released from the interlock end and track extension  21  is again locked in the retracted position enabling roller bracket  25  to slide through track extension  21  back into primary track  20  for normal closing of the sliding door. 
         [0019]    A preferred interlock mechanism of the present invention is also shown in  FIGS. 6-10 . A lever  45  is mounted by a hinge pin  46  onto track extension  21 . Lever  45  has a roller recess  47  adapted to capture a roller  30 . Lever  45  also has a capture slot  48  for receiving a fulcrum pin  50  which is mounted on concentric track bracket  22 . In the normal locked position shown in  FIG. 6 , lever  45  is rotated to the maximum extent in the counter clockwise direction with fulcrum pin  50  captured at the end of slot  48 . Lever  45  is preferably held in place by a detent mechanism (not shown). In this position, roller  30  clears the leading edge of recess  47  so that it can freely move into or away from recess  47 . As shown in  FIGS. 7-9 , movement of roller  30  toward the left causes clockwise rotation of lever  45  until fulcrum pin  50  escapes slot  48 . In the normal unlocked position, roller  30  is fully captured in recess  47  and track extension  21  is released and free to move rearward as shown in  FIG. 10  by forces transmitted through roller  30 . During the door closing process, the sequence of  FIGS. 6-10  is reversed whereby track extension  21  retracts within concentric track bracket  22  causing slot  48  to approach fulcrum pin  50 . Because of the sloped surface of slot  48 , the action of fulcrum pin  50  against slot  48  causes lever  45  to rotate in the counter clockwise direction until roller  30  is released from recess  47 , whereupon track extension  21  becomes locked in the retracted position. 
         [0020]      FIG. 11  shows the interlock in an end view wherein appropriate flanges are formed on track extension  21  and concentric track bracket  22  to retain hinge pin  46  and fulcrum pin  50 . In addition, bearing races  51  and  52  are shown for achieving the sliding capability of track extension  21  within concentric track bracket  22 . 
         [0021]      FIG. 12  shows a top view of the interlock mechanism. Concentric track bracket  22  has an upper slot  53  for accommodating the interlock mechanism. Concentric track bracket  22  is shown mounted to one section of a vehicle side panel  34 . Depending upon the particular styling of the vehicle, an opening or slot (not shown) may be provided elsewhere in panel  34  for accommodating the roller bracket and track extension (i.e., so that the track extension can slide out through the slot in order to extend beyond the rear end of the vehicle). For aesthetic purposes, it may be desirable to provide an end cap or other finish piece (not shown) at the end of the track extension that plugs the slot in the body panel when the track extension is in the retracted position. 
         [0022]    While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.