Abstract:
A latch assembly includes a plunger having a ramp and a lip, with a support member defining an opening through which the plunger extends. A support surface partially defines the opening and supports the plunger. The plunger is selectively movable between an extended position, in which the plunger protrudes a first distance from the opening, and a retracted position, in which the plunger protrudes a second distance from the opening, with the second distance being less than the first distance. In the extended position, the ramp and the lip are on a first side of the opening. In contrast, in the retracted position, the ramp and the lip are on a second side of the opening, with the lip engaging the support member to maintain the retracted position.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to roll-out load floors for automotive vehicles and, more particularly, to a locking mechanism for securely maintaining a sliding load floor in a desired position.  
       BACKGROUND OF THE INVENTION  
       [0002]     Typical roll-out load floors slide along a track between a rearward extended position for loading and unloading, and a forward stowed position for load transport. A locking mechanism maintains the load floor in the stowed position or the extended position, or in another position relative to the track. A typical locking mechanism includes a latch member fixed to one of either the load floor or the track, and a plurality of detent members fixed to the other of the load floor or the track. When the latch member engages one of the detent members, the load floor is in a locked condition with respect to the track. To unlock the load floor, an operator typically disengages the latch member from the detent member, thereby allowing the load floor to slide along the track.  
       SUMMARY OF THE INVENTION  
       [0003]     A latch assembly is provided. The latch assembly includes a plunger defining a ramp and a lip, a spring, and a support member defining an opening through which the plunger extends. The spring biases the plunger toward an extended position in which the plunger protrudes a first distance from the opening. The plunger is selectively movable from the extended position to a retracted position in which the plunger protrudes a second distance from the opening, the second distance being less than the first distance, and in which the lip engages the support member to counteract the spring and thereby maintain the plunger in the retracted position.  
         [0004]     The latch assembly may be used to selectively lock a movable member with respect to a stationary member. In the extended position, the plunger is engageable with a slot in a stop member to prevent or restrict relative movement between the movable and the stationary members. In the retracted position, the plunger is not engageable with the slot, and, accordingly, does not interfere with relative movement between the stationary member and the movable member.  
         [0005]     The latch assembly of the invention enables positive disengagement of the plunger from a slot, i.e., once an operator retracts the plunger, the plunger remains in the retracted position without continued operator effort. The latch assembly of the invention also enables automatic resetting of the plunger to the extended position so that it will automatically engage a slot without operator effort or intervention when appropriately aligned with respect to the stop member.  
         [0006]     Accordingly, an apparatus is provided having a first member, a second member selectively movable between a first position and a second position with respect to the first member, a stop member connected to one of the first and second members, and a latch assembly connected to the other of the first and second members. The stop member defines a slot and a ramp. The latch assembly includes a plunger defining a ramp and a lip, a spring, and a support member defining an opening through which the plunger extends. The spring biases the plunger toward an extended position in which the plunger protrudes a first distance from the opening sufficient for the plunger to engage the slot when the second member is in the first position to prevent or restrict relative movement between the first and second members.  
         [0007]     The plunger is selectively movable from the extended position to a retracted position in which the plunger does not engage the slot, and in which the lip engages the support member to counteract the spring and thereby maintain the plunger in the retracted position. Thus, when the plunger is in the retracted position, the second member is movable to the second position.  
         [0008]     The stop member includes a geometrical feature, such as a ramp, that is sufficiently positioned to contact the plunger during movement of the second member from the first position to the second position, and thereby cause the lip to disengage the support member so that the spring moves the plunger to the extended position. The plunger is thus automatically reset to engage another slot when the second member is in the second position.  
         [0009]     In an exemplary embodiment, the first member is a track, and the second member is a vehicle cargo load floor translatable along the track between a stowed position and an extended position. Accordingly, a load floor operator need only move the plunger to the retracted position to move the load floor from the stowed position. The latch assembly will automatically engage another stop when the load floor is in the extended position without operator effort, thereby reducing or eliminating the possibility of load floor over-extension beyond the extended position.  
         [0010]     The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a schematic perspective view of a sliding load floor incorporating a locking mechanism according to the present invention;  
         [0012]      FIG. 2  is a schematic perspective view of a latch assembly and a detent member of the locking mechanism of  FIG. 1 ;  
         [0013]      FIG. 3  is a schematic, partial cutaway, perspective view of the latch assembly and the detent member of  FIG. 2 ;  
         [0014]      FIG. 4  is a schematic sectional side view of the latch assembly and the detent member of  FIG. 2  with the latch assembly plunger in an extended position; and  
         [0015]      FIG. 5  is a schematic sectional side view of the latch assembly and the detent member of  FIG. 2  with the latch assembly plunger in a retracted position.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     Referring to  FIG. 1 , a sliding load floor assembly incorporating a locking mechanism  10  according to the present invention is shown at  4 . The sliding load floor assembly  4  includes a sliding member  6  for receiving a load floor slidable along a track  8 . Each side of the sliding load floor assembly  4  includes a locking mechanism, shown at  10  in  FIGS. 2-5 , comprising at least one latch assembly  12  and first and second stop members  14 ,  15 , also referred to herein as “detent members.” For ease of description, it will be assumed throughout that the detent members  14 ,  15  attach to a stationary member such as the track  8  or a vehicle floor, while the latch assembly  12  attaches to a movable member such as the sliding platform  6 . However, it should be appreciated that the detent members  14 ,  15  could attach to the movable member and the latch assembly  12  to the stationary member without changing the inventive concept.  
         [0017]     An exemplary load floor assembly with which the locking mechanism may be employed is described in commonly assigned U.S. patent application Ser. No. 11/007871 filed Dec. 9, 2004, entitled “Sliding Vehicle Load Floor,” Bartos et al., and hereby incorporated by reference in its entirety.  
         [0018]     Referring to  FIGS. 2 and 3 , the latch assembly  12  comprises a plunger  16  supported within a housing  20 , which acts as a support member. The plunger  16  extends at least partially through a plunger opening  22  within the housing  20 , and rests upon a supporting surface  23  that partially defines the plunger opening  22 . The plunger  16  includes a distal end  34 , a lip  40 , an inclined plunger ramp  38  slanting downward from the lip  40 , a shoulder  24 , and a rod  18 . The shoulder  24  interferes with the housing  20  to prevent overextension of the plunger  16  through the plunger opening  22 . The rod  18  extends through a rod opening  26  within a biasing plate  28  extending from the plunger housing  20 . A spring  30  surrounds the rod  18  and extends between the shoulder  24  and the biasing plate  28  to bias the plunger  16  toward an extended position, as shown in  FIG. 3 . The distal end  34  of the plunger  16  is noncircular in cross-section (preferably square as shown, and interacts with the detent members  14 ,  15  as described herein to lock the sliding platform  6  in a plurality of positions with respect to the track  8 . The opening  22  is also noncircular in cross section, and is square in the embodiment depicted. The noncircular cross sections of the plunger and the opening prevent rotation of the plunger about its axis.  
         [0019]     Referring to  FIGS. 4 and 5 , wherein like reference numbers refer to like components from  FIGS. 1-3 , the locking mechanism  10  includes a flexible Bowden-style cable  48  movable within a sheath  44 . The cable  48  is preferably operatively connected to a handle assembly, shown generally at  49  in  FIG. 1 . The cable  48  attaches to a post  50  extending upward toward the rod  18 . A rod pin  52  extends through the rod  18  and attaches the post  50  thereto.  
         [0020]     To retract the plunger  16 , i.e., to move the plunger from the extended position shown in  FIG. 4  to the retracted position shown in  FIG. 5 , a force is applied to the handle assembly, shown at  49  in  FIG. 1 . The cable  48  transmits the force from the handle assembly to the plunger  16  via the post  50 , thereby compressing the spring  30  and drawing the ramp  38  and lip  40  through the opening  22 . Since the cable  48  is attached to the plunger via pin  50 , the vector of the force exerted by the cable is not coincident with the axis of the plunger, thereby inducing, in addition to lateral translation of the plunger, a tendency of the plunger to rotate about an axis perpendicular to the force vector. As the plunger  16  moves into the housing  20 , the plunger ramp  38 , being inclined, traverses the supporting surface  23  of the plunger opening  22 , and as the plunger  16  tilts downward, a vertical clearance  54  is established between the plunger  16  and the housing  20  within the plunger opening  22 .  
         [0021]     The rod opening  26  is slightly larger than the rod  18 , allowing the rod  18  to pivot about the rod opening  26  as the plunger  16  rotates. The plunger  16  continues movement into the housing  20  until the lip  40  on the plunger  16  drops into the housing  20  such that the plunger  16  reaches the retracted position shown in  FIG. 5 . In the retracted position, the vertical clearance  54  is maximized. A plunger pin  56  extending through the plunger  16  prevents overretraction of the plunger  16  into the housing  20  by interfering with the housing  20 . Movement of the plunger  16  into the housing compresses the spring  30  between the shoulder  24  and the biasing plate  28 . The lip  40  on the plunger  16  interferes with the plunger housing  20 , preventing the spring  30  from urging the plunger  16  back out of the housing  20  and into the extended position.  
         [0022]     It should be appreciated that the detent members  14 ,  15  are substantially identical, such that description of detent member  14  suffices as a description of detent member  15 . Referring again to  FIGS. 2 and 3 , the detent member  14  comprises a locking portion  58  and two resetting portions  60 . The detent member  14  may be comprised of one or more pieces within the scope of the claimed invention. The locking portion  58  defines a locking slot  64  for receiving the distal end  34  of the plunger  16 . The locking slot  64  is substantially the same width as the distal end  34  of the plunger  16  to sufficiently lock the plunger  16  within the locking slot  64  as described herein. A pair of locking ramps  66  define the locking slot  64  therebetween. Each of the resetting portions  60  includes an inner resetting ramp  72  extending upward from a clearance slot  70  to a top face  74 , and an outer ramp  76  sloping downward away from the top face  74 .  
         [0023]     In operation, the plunger  16  is retracted as described above, freeing the sliding platform  6  to move along the track  8 . When the plunger  16  is fully retracted, the distal end  34  rests within the clearance slot  70  between the resetting ramps  72 . Since the clearance slot  70  is wider than the locking slot  64 , and thus wider than the distal end  34  of the plunger  16 , the plunger  16  will not contact the detent member  14  during initial load floor movement. Thus the latch assembly  12  initially moves, with the sliding platform  6  to which it is attached, within the clearance slot  70  to a position where the plunger  16 , even if released, will not reengage the locking slot  64  due to interference with one of the ramps  66 .  
         [0024]     As the latch assembly  12  continues movement with respect to the detent member  14 , the plunger  16  contacts the inner resetting ramp  72  of one of the resetting portions  60 . Relative movement of the plunger and the ramp  72  will cause the plunger to rotate, thereby disengaging the lip  40  from the housing  20  and allowing the spring  30  to force the plunger  16  out of the housing  20  toward the locking slot  64 . As the plunger  16  extends, the plunger ramp  38  acts against the plunger opening  22  to increase rotation of the plunger  16 . One of the locking ramps  66  initially pushes against the plunger  16 , disallowing full extension thereof. However, once the plunger  16  clears the locking ramp as the load floor is moved, full extension is realized, and the plunger  16  reaches the extended position shown in  FIG. 4 .  
         [0025]     To relock the locking mechanism  10 , the sliding platform  6  moves along the track  8 , thereby moving the latch assembly  12  toward one of the detent members  14 ,  15 . For ease of description, it will be assumed that the sliding platform  6  moves the latch assembly  12  toward detent member  15  to lock the sliding platform  6  in a different position. However, it should be appreciated that the sliding platform  6  could also move back toward detent member  14  without changing operation of the invention. The plunger  16  contacts one of the locking ramps  66  of detent member  15 , which pushes the plunger  16  back into the housing  20 , thereby compressing the spring  30 . The locking ramp  66  is designed so as not to push the plunger  16  fully into the retracted position. Instead, the plunger  16  slides along the locking ramp  66  to store potential energy within the spring  30 . When the plunger  16  reaches the locking slot  64 , the potential energy stored within the spring  30  pushes the plunger  16  into the locking slot  64  to lock the sliding platform  6  in position.  
         [0026]     In the preferred embodiment, three detent members  14 ,  15 ,  15 ′ are included to lock the load floor in three positions: stowed, mid-extension and full extension. Each detent member  14 ,  15 ,  15 ′ works as described herein. The locking ramps  66  are identical, such that relocking is facilitated from either direction. Additionally, it should be appreciated that a plurality of latch assemblies  12  may be utilized in conjunction with a single detent member  14  without changing the inventive concept. However, since the detent members  14 ,  15 ,  15 ′ have fewer parts and cost less than the latch assembly  12 , this is not the preferred method of practicing the invention.  
         [0027]     While the best modes for carrying out the invention have been described in detail, it is to be understood that the terminology used is intended to be in the nature of words and description rather than of limitation. Those familiar with the art to which this invention relates will recognize that many modifications of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced in a substantially equivalent way other than as specifically described herein.