Patent Abstract:
A cable drive assembly for opening and closing a sliding vehicle door has first and second drums that are drivingly connected to each other via a tension spring that biases the drums in opposite directions. The drums include a catch that holds the first and second drums in a cocked condition where the spring is tensioned to provide slack in a closed loop cable to facilitate inserting a traveler attached to the cable into a track. The cocked drums are manually rotated in a drum housing in one direction to move the traveler and insert it into the track. After the traveler is inserted, the cocked drums are manually rotated in the opposite direction. This releases the catch so that the tensioned spring takes up the slack in the closed loop cable.

Full Description:
RELATED APPLICATION 
   This patent application claims benefit of U.S. Provisional patent application 60/415,582 filed Oct. 2, 2002. 

   TECHNICAL FIELD 
   This invention relates generally to a power operated sliding door closure system for opening and closing a sliding door on a vehicle and more particularly to a cable drive assembly for such a system. 
   BACKGROUND OF THE INVENTION 
   Van type vehicles for passengers and for cargo are frequently equipped with sliding side doors. Many vans include a single sliding door on the passenger side of the van. However, the van may be equipped with sliding doors on both sides. Drivers and passengers can open or close sliding doors of this type manually from inside or outside of the vehicle. However, the sliding door is usually heavy and often inconvenient and/or difficult to move manually, particularly from inside the vehicle. 
   For convenience, power operated sliding door closure systems have been developed to allow drivers and passengers to open and close a sliding door virtually effortlessly. Moreover the sliding door usually can be opened or closed from the driver&#39;s seat and/or one or more other locations remote from the sliding door. 
   One type of power operated sliding door closure system, known as a “closed loop” system, is disclosed in U.S. Pat. No. 5,396,158 which issued Mar. 7, 1995 to Joseph D. Long et al. The Long et al. &#39;158 patent discloses a power operated sliding door closure system in which a sliding door is mounted on a van by travelers that are slidably supported in upper, center and lower tracks. An opening and closing module is mounted inside the van adjacent the center track. A front cable is attached to a front cable drive pulley or drum and extends from the front drum to the traveler through a front cable roller guide assembly. A rear cable is attached to a rear cable drive pulley or drum and extends from the rear drum to the traveler through a rear cable roller guide assembly. The front and rear cable drive drums each have a large diameter helical cable groove. 
   A motor drive unit rotates the front and rear cable drive drums to move the sliding door. The motor drive unit, as best shown in FIG. 3 of the Long et al. &#39;158 patent, comprises an electric motor that drives a drive gear that is coaxially aligned with the front and rear cable drive drums. A coil spring is seated in an annular opening in the cable drive drums. An upper spring end is anchored on the rear cable drive drum and a lower spring end is anchored on the front cable drive drum. The coil spring is a tension retaining spring that urges the front cable drive drum in the counterclockwise winding direction and the rear cable drive spool in the opposite clockwise winding direction so that the front and rear cables are maintained in tension at all times. 
   While the “closed loop” type of system disclosed in the Long et al. &#39;158 patent is satisfactory for its intended purpose, assembly of the system may be difficult because of the tension retaining spring that takes up slack and insures that the front and rear cables are maintained in tension at all times. Considerable slack is often desired to facilitate assembly of the closed loop system because the traveler (roller hinge assembly shown at 26 in the Long et al. &#39;158 patent) must be inserted into the track (usually the center track shown at 18 in the Long et al. &#39;158 patent) after the ends of the front and rear cables are attached to the traveler. However, the coil spring in the system noted above, must be tensioned or wound up to provide any slack at all and even then the slack may not be enough to facilitate insertion of the traveler into one end of the track. Furthermore even with sufficient slack, the cables may not position the traveler correctly for insertion into the one end of the track. 
   Another way to take up slack in a “closed loop” system is disclosed in the U.S. Pat. Nos. 5,319,880 and 5,319,881 granted to Howard W. Kuhlman Jun. 14, 1994. These patents disclose a mechanical take-up device comprising a small cable slack take-up pulley 174 and a cooperating tooth rack 172 mounted on the cable pulley. One end of one of the cables is attached to the small cable slack take-up pulley. After both cables are attached to the traveler and the traveler is inserted into the track, the cable slack is taken up by rotating the small cable slack take-up pulley with a special tool. See also pending patent application Ser. No. 09/970,167 filed Oct. 3, 2001. The mechanical take up device facilitates assembly by allowing sufficient slack in the cables. However, the cables still may not position the traveler correctly. Moreover, the take-up device is complicated and expensive and requires a special tool for operation. 
   SUMMARY OF THE INVENTION 
   According to the invention, a cable drive assembly for a power operated sliding door closure system on a vehicle is provided that facilitates insertion of a traveler into a track and takes up slack in the cables attached to the traveler in an efficient and unique manner. 
   The drive assembly includes front and rear drums with helical front and rear cable grooves respectively that are supported for rotation about a longitudinal axis. A front cable extends from the front cable groove to a traveler attached to a vehicle sliding door in a position to be wound into and unwound from the front cable groove in response to front drum rotation in respective opposing directions about the longitudinal axis. A rear cable extends from the rear cable groove to the traveler for the sliding door in a position to be unwound from and wound onto the rear cable groove in response to rear drum rotation in respective opposing directions about the longitudinal axis. The cable drive unit also includes a spring that biases the front drum and the rear drum in opposite directions to maintain the front and rear cables in tension. 
   The front and rear drums are configured to provide a catch that holds the front and rear drums in a cocked condition where the spring is tensioned so that the cable purposely has slack to facilitate inserting the traveler into a track during assembly. The cocked drums are rotatable in a drum housing which has a catch release. The cocked drums are manually rotated in the drum housing in one direction, preferably by pulling on one of the cables, to move the traveler and position the traveler for insertion into one end of the track. After the traveler has been inserted into the track, the cocked drums are manually rotated in the drum housing in the opposite direction, preferably by pulling on the other cable. This operates the catch release in the drum housing which releases the catch holding the drums in the cocked condition. When released, the spring rotates the drums relative to each other and takes up the slack in the cables. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the invention will become apparent to those skilled in the art in connection with the following detailed description and drawings, in which: 
       FIG. 1  is a schematic perspective view of a power operated sliding door closure system having a cable drive assembly constructed according to the invention. 
       FIG. 2  is an exploded perspective view of a cable drive assembly constructed according to the invention; 
       FIG. 3  is an opposite end view of one of the cable drums shown in  FIG. 2 ; 
       FIG. 4  is a section of the cable drive assembly showing the cable drums, in a cocked position; 
       FIG. 5  is a section similar to  FIG. 4  showing the cocked cable drums being rotated in the cable drum housing in a first direction to position a traveler for insertion into the end of a guide track; 
       FIG. 6  is a section similar to  FIG. 4  showing the cocked cable drums being rotated in the cable drum housing in an opposite direction to release the cocked cable drums so that the cable tensioning spring takes up the slack in the cables; 
       FIG. 7  is a section taken substantially along the line  7 — 7  of  FIG. 5  looking in the direction of the arrows. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A closed loop power operated sliding of a door closure system for opening and closing a sliding door on a vehicle is generally shown at  20  in FIG.  1 . In  FIG. 1  the system  20  is shown configured to be installed in a van that includes a sliding door supported on a plurality of tracks mounted on a vehicle frame, typically a top track, a bottom track and a center track. The system  20  includes a traveler, shown at  22  in  FIG. 1 , that connects the closure system  20  to the sliding door (not shown). The door closure system moves the sliding door and traveler  22  along one of the tracks, usually the center track shown at  21  in  FIG. 1 , between a closed position and an open position. The closed loop cable closure system  20  is mounted on the vehicle frame and includes a cable drive assembly  24 . 
   The cable drive assembly  24  constructed according to the invention may be used in a closed loop cable closure system  20  such as that described in U.S. Pat. No. 5,396,158 which is described above and incorporated herein by reference. 
   Referring now to  FIG. 2 , the cable drive assembly  24  comprises a motor sub-assembly  26  that is attached to the exterior of a housing  28 . Motor sub-assembly  26  includes a reversible electric motor  30  that drives a reduction gear unit  32  that has an output shaft  34 . Output shaft  34  extends into housing  28  on a longitudinal axis  36  to drive an electromagnetic clutch indicated generally at  38 . Electromagnetic clutch  38  is disposed inside housing  28  along with an interrupter  40 , a front drum  42 , a tension spring  44 , and a rear drum  46 . Housing  28  is closed by a cover  48 . 
   Interrupter  40  comprises a plate having an integral annular sleeve  41  that is journalled on shaft  34  for concentric rotation about shaft  34  and longitudinal axis  36 . Sleeve  41  extends through respective bores of front and rear drums  42 ,  46  and supports the front and rear drums  42 ,  46  rotationally on axis  36 . The free end of sleeve  41  attaches to a friction output plate of electromagnetic clutch  38 . The plate of the interrupter  40  has a plurality of circumferentially spaced windows that cooperate with an optical sensor (not shown) to determine the speed and location of the van door (not shown) in the opening and closing operations. The output shaft  34  of the motor sub-assembly  26  extends through annular sleeve  41  of the interrupter  40  and drives the input member of the electromagnetic clutch  38 . Electromagnetic clutch  38  operates in a conventional manner to drive the friction plate of the electromagnetic clutch  38  when energized while allowing free rotation of the friction plate when deenergized. This facilitates manual operation of the van door by eliminating the necessity to back drive electric motor  30 . 
   Front drum  42  is cup shaped having an end wall with a large diameter rim  50  that includes a helical front cable groove  52  and a cable anchor slot  54  in rim  50  that communicates with the front cable groove  52  as best shown in FIG.  2 . Front drum  42  has an integral pin shaped lug  55  that extends from rim  50  in an axial direction. Lug  55  serves as a spring anchor and as well as a catch lug as explained below. 
   Rear drum  46  is also cup shaped having a large diameter outer rim  56  that includes a helical rear cable groove  58  and a reduced diameter hub  60 . A radial wall  62  and radial ribs  64  connect rim  56  to hub  60 . The radial ribs  64  are on one side of wall  62 . The space between rim  56  and hub  60  on the other side of wall  62  provides an annular spring chamber  66  of about 350° as best shown in FIG.  3 . Chamber  66  has a pin shaped spring anchor lug  68  at one end and a fixed stop  70  at the other end. Stop  70  is part of a trapezoidal lug  72  of about 10° that fills the space between rim  56  and hub  60 . Lug  72  also provides a cable anchor slot  74 . 
   Rear drum  46  includes a spring catch  76  comprising an accurately shaped, flexible cantilever arm  78  attached to an end of radial wall  62 . Catch  76  includes a moveable stop face  80  near the free end of flexible arm  78  and a ramp  82  leading up to stop face  80  from a point closer to the fixed end of the flexible arm  78 . Catch  76  also has a cam follower  84 . Cam follower  84  is bidirectional having inner and outer cam follower surfaces  86  and  88  that are ramped at opposite ends resulting in a diamond or parallelogram like shape for the follower  84 . The cam follower  84  is attached to the free end of the flexible arm  78  at one side so that the entire peripheral surface of the cam follower  84  that provides the cam follower surfaces  86  and  88  is engageable by a cam as explained below. 
   Rear drum  46  is partially nested in front drum  42  with its rim  50  juxtaposed rim  56  as best shown in FIG.  4 . Tension spring  44  is disposed in spring chamber  66  with one end attached to spring anchor lug  55  and the other end attached to spring anchor lug  68 . When in tension, tension spring  44  biases front drum  42  counterclockwise and rear drum  46  clockwise as viewed in FIG.  2 . 
   Tension spring  44  is pre-tensioned by rotating front drum  42  clockwise with respect to rear drum  46  until spring anchor lug  55  engages ramp  82  as shown in phantom in FIG.  4  and then continues along the ramp  82  until it snaps behind stop face  80  of spring catch  76  as shown in solid line in FIG.  4 . Drums  42  and  46  are now in a cocked condition. Stop  70  of lug  72  limits further clockwise rotation. Cocked drums  42  and  46  are disposed inside housing  28  which has a catch release  90  attached to cover  48 . 
   Catch release  90  comprises a flexible strip  92  of cover  48  which supports a cam  94 . Cam  94  is bidirectional having inner and outer cam surfaces  96  and  98  that are ramped at opposite ends resulting in a diamond or parallelogram like shape for the cam  94 . Cam  94  is attached to the flexible strip  92  at one side so that the entire peripheral surface of cam  94  that provides cam surfaces  96  and  98  is engageable by cam follower  84  as shown in FIG.  7  and further explained below. 
   Front and rear cables  100  and  102  shown in  FIG. 1 , are anchored in drums  42  and  46  respectively and wound in opposite circumferential directions around the respective drums  42  and  46 . Cables  100  and  102  extend from the respective drums  42  and  46  in the opposite tangential directions and out respective exits of housing  28 . In operation, front cable  100  wraps onto front drum  42  while rear cable  102  unwraps from rear drum  46  and vice-versa. 
   The front cable  100  extends from the front cable groove of drum  42  to the sliding door traveler  22  in a position to be wound onto the drum  42  and into the front cable groove in response to front drum  42  and front cable groove rotation about the longitudinal axis  36  in a forward direction (counterclockwise as shown in  FIG. 1 ) which closes the sliding door of the van (not shown). When the drum  42  and front cable groove rotate in a reverse or clockwise direction, opposite the forward direction to open the sliding door, the front cable  100  winds off of the drum  42  and out of the front cable groove. 
   Similarly, the rear cable  102  extends from the rear cable groove to the sliding door traveler  22  in a position to be wound off of the drum  46  from the rear cable groove in response to drum  46  and rear cable groove rotation about the longitudinal axis  36  in the forward or counterclockwise direction which closes the sliding door. When the drum  46  and rear cable groove rotate in the reverse or clockwise direction to open the sliding door, the rear cable  102  winds onto the drum  46  into the rear cable groove. 
   The cable drive assembly  24  with cables  100  and  102  is manufactured at one location and then delivered to an assembly plant where it is attached to a vehicle so as to become a part of the power operated sliding door closure system shown in FIG.  1 . 
   In initial steps of the assembly process, cable drive assembly  24  is attached to a vehicle and cables  100  and  102  are attached to the traveler  22 . Traveler  22  must then be inserted into the guide track  21  which has already been attached to the vehicle as part of the body build. 
   When attached to the vehicle, cable drive assembly  24  is in the cocked condition which provides slack in cables  100  and  102  to facilitate insertion of traveler  22  into guide track  21 . However, traveler  22  may not be positioned correctly for insertion into the end of the guide track  21 . For instance, the traveler  22  should be positioned at  23  as shown in  FIG. 1  whereas traveler may be positioned a few feet away from this ideal location. 
   Traveler  22  can be moved to the ideal location at  23  easily because of the bidirectional nature of cam  94  and cam follower  84 . The cocked drums  42  and  46  are simply rotated relative to the housing  28  in the proper direction as shown in FIG.  5 . When the cocked drums  42  and  46  are rotated in this direction, catch  76  is not released. When catch  76  approaches catch release  90  from the right as shown in  FIG. 5 , inner cam surface  96  of cam  94  engages outer cam follower surface  88  of cam follower  84 . This simply raises cam  94  and/or pushes catch  76  deeper into spring chamber  66 . In either event, catch lug  55  is held in the cocked position of  FIG. 4  by spring catch  76 . 
   Traveler  22  is moved to the ideal location, preferably by pulling cable  102  to rotate the cocked drums  42  and  46  in the proper direction. Traveler  22  is then inserted into guide track  21 . The cables  100  and  102  are then properly located on any guide pulleys, such as guide pulleys  25  and  27  shown in FIG.  1 . 
   Once the system is assembled, slack in cables  100  and  102  is taken-up by releasing spring catch  76 . Spring catch  76  is released simply by rotating the cocked drums  42  and  46  in the opposite direction. When the cocked drums  42  and  46  are rotated in the opposite direction, spring catch  76  is released. When catch  76  approaches catch release  90  from the right as shown in  FIG. 6 , outer cam surface  98  of cam  94  engages inner cam follower surface  86  of cam follower  84 . This lifts catch  76  away from catch lug  55  and tension spring  44  contracts, rotating drum  42  with respect to drum  46  to take up slack in cables  100  and  102 . 
   Cable drive assembly  24  now operates in the following manner. 
   As shown in  FIG. 2 , electric motor  30  is drivingly connected to the input member of electromagnetic clutch  38 . For closure, electric motor  30  is energized to drive output shaft  34  and the input member connected to it in the forward direction, i.e. clockwise. At the same time electromagnetic clutch  38  is energized so that the input member drives the friction plate which in turn rotates drum  42  and its cable groove  50  in the forward or clockwise direction. Clockwise rotation about the longitudinal axis  36  winds front cable  100  onto drum  42  to close the sliding door (not shown). As drum  42  is driven clockwise, drum  46  is pulled clockwise via tension spring  44 , winding rear cable  102  off of drum  46 ; with drum  46  being biased counterclockwise by tension spring  44  to maintain tension in cables  100  and  102 . 
   When the sliding door of the van door is closed, electric motor  30  and electromagnetic clutch  38  are deenergized through a suitable control (not shown). 
   To open the sliding door (not shown), electric motor  30  and electromagnetic clutch  38  are energized to drive output shaft  34  and the friction plate in the rearward direction, i.e. counterclockwise. The friction plate in turn rotates the rear drum  46  and its cable groove in the rearward or counterclockwise direction. Counterclockwise rotation about the longitudinal axis  36  winds rear cable  102  onto drum  46  to open the sliding door (not shown). As drum  46  is driven counterclockwise, tension spring  44  pulls front drum  42  counterclockwise winding front cable  100  out of cable groove and off of drum  42 ; with drum  42  being biased clockwise by tension spring  44  to maintain tension in cables  100  and  102 . 
   The above description is intended to illustrate a preferred embodiment of the invention rather than to limit the invention. Therefore, it uses descriptive rather than limiting words. Obviously, it&#39;s possible to modify this invention from what the description teaches. Within the scope of the claims, one may practice the invention other than as described.

Technology Classification (CPC): 4