Cable drive assembly

A cable drive unit for opening and closing a sliding door on a vehicle (not shown) has a cup-shaped front drum having a helical front cable groove and a rear cup-shaped drum having a helical rear cable groove. The front drum is rotated about a longitudinal axis in a first direction to open the sliding door. The rear drum is partially nested in the front drum and rotated about the longitudinal axis in an opposite direction to close the sliding door. The front drum and the rear drum are drivingly connected to each other via a tension spring that biases the front drum and the rear drum in opposite directions when in tension. The front and rear drums are rotated by a concentric clutch that is nested in the rear drum. The clutch includes a drive member that is drivingly connected to the front drum via a first lost motion connection and drivingly connected to the rear drum via a second lost motion connection. The first drum has an arcuate slot forming part of the first lost motion connection, the rear drum has an arcuate slot forming part of the second lost motion connection, and the drive member has a tab that projects through both arcuate slots to form part of the first lost motion connection and part of the second lost motion connection.

TECHNICAL FIELD

This invention relates generally to a sliding door closure apparatus for opening and closing a sliding door on a vehicle.

BACKGROUND OF THE INVENTION

Van type vehicles for passengers and for cargo are frequently equipped with sliding side doors. Rollers support and guide such sliding doors by running in fixed tracks. Sliding doors may be positioned on both sides of a vehicle or a single sliding door may be positioned on one side of the vehicle. However, most vans include a single sliding door positioned on the side of the van opposite the vehicle operator's station. When seated at the vehicle operator's station, a vehicle operator can open or close sliding doors of this type only by leaving the operator's station and either walking around the outside of the vehicle to the sliding door or crossing inside the vehicle to the sliding door. Crossing inside the vehicle is often difficult or impossible due to the presence of cargo and/or passengers positioned inside the van between the operator's station and the door. If a sliding door is positioned on the same side of the van as the operator's station, the operator still must leave the operator's station to open and shut the sliding door from either the inside or outside of the vehicle.

To allow an operator to open and close a sliding door from the operator's station and/or another location remote from the sliding door, power operated sliding door closure systems have been developed. An example of such a 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. patent discloses a sliding door closure apparatus that includes a sliding door mounted in a van on rollers and 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 sliding door 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 sliding door 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 inFIG. 3of the '158 patent, comprises an electric motor that drives a drive gear that is coaxially aligned with the front and rear cable drive drums. A lost motion connection is provided between the drive gear and the front cable drive drum in the form of a drive lug that is carried by the drive gear and a complementary drive lug that is carried by the front cable drive drum. A lost motion connection is also provided between the drive gear and the rear cable drive drum in the form of a second drive lug that is carried by the drive spool and a second complementary lug that is carried by the rear cable drive drum. As seen inFIGS. 2 and 3of the '158 patent, 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.

SUMMARY OF THE INVENTION

According to the invention, a cable drive assembly for opening and closing a sliding door on a vehicle is provided. 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 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 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 direction to maintain the front and rear cables in tension.

The front and rear drums are configured to provide a nesting chamber for an electromagnetic clutch resulting in a very compact arrangement in the axial direction. The electromagnetic clutch is preferably coaxially arranged with the drums and the output shaft of an electric motor subassembly to contribute to the axial compactness of the cable drive assembly. The front drum is adapted to drive the side door to a closed position by including a decreasing earn portion that increases the tensile force in the cable to overcome the opposing load created by the door seals during the final closing operation with the cam portion preferably being elliptical to increase cable life.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following is a description of a cable drive assembly10constructed according to the invention and configured for use in a closed loop cable closure system such as that described in U.S. Pat. No. 5, 396,158 which is incorporated herein by reference.

The cable drive assembly10comprises a motor sub-assembly12that is attached to the exterior of a housing14. Motor sub-assembly12includes a reversible electric motor16that drives a reduction gear unit18that has an output shaft20. Output shaft20extends into housing14on a longitudinal axis21to drive an electromagnetic clutch indicated generally at22. Electromagnetic clutch22is disposed inside housing14along with an interrupter24, a front drum26, a tension spring28, and a rear drum30. Housing14is closed by a cover32.

Interrupter24comprises a plate34having an integral annular sleeve36that is journalled on shaft20for concentric rotation about shaft20and longitudinal axis21. Sleeve36extends through respective bores of front and rear drums26,30and supports the front and rear drums26,30rotationally on axis21. The free end of sleeve36attaches to a friction output plate38of electromagnetic clutch22. Plate34has a plurality of circumferentially spaced windows40that cooperate with an optical sensor42to determine the speed and location of the van door (not shown) in the opening and closing operations. The output shaft20of the motor sub-assembly12extends through the annular sleeve36and drives the input member44of the electromagnetic clutch22. Electromagnetic clutch22operates in a conventional manner to drive plate38when energized while allowing free rotation of plate38when deenergized. This facilitates manual operation of the van door by eliminating the necessity to back drive electric motor16.

Front drum26is cup shaped having an end wall50with a large diameter rim52that includes a helical front cable groove54and a decreasing diameter cam portion56on one end that includes a continuation of the front cable groove54. Front drum26has a cable anchor58in rim52that communicates with the front cable groove54at the opposite end as best shown inFIGS. 2 and 3. End wall50includes an arcuate lost motion slot60while rim52includes a spring groove62in its end face and a spring tab64that projects from the end face of rim52in an axial direction.

Rear drum30is also cup shaped having an end wall66with a large diameter rim68that includes a helical rear cable groove70and a reduced diameter annular cylindrical wall72that connects rim68to end wall66. Rear drum30is partially nested in front drum26with its rim68juxtaposed rim52as best shown infigure 2. Rim68includes a cable anchor71that communicates with helical rear cable groove70and a spring cavity74that aligns with spring groove54so that spring tab64extends into spring cavity74. Spring cavity74has an abutment76at one end. End wall66and reduced diameter cylindrical wall72form a nesting chamber77for electromagnetic clutch22.

Tension spring28is disposed in spring cavity74so that one end of tension spring28engages abutment76and the other end of tension spring28engages spring tab64. When in tension, tension spring28biases drum26counterclockwise and drum30clockwise as viewed inFIGS. 1 and 5.

Rear drum30includes an arcuate lost motion slot78in the end wall66that aligns or at least overlaps lost motion slot60of front drum26when rear drum is nested part way in front drum26. When so nested, stop63(FIG. 3) of front drum26is disposed in lost motion slot78of rear drum30while stop79of rear drum30is disposed in lost motion slot60of front drum26. Stops63and79cooperate with the respective lost motion slots78and60to limit the relative angular displacement of front drum26with respect to rear drum30.

The output friction plate38of electromagnetic clutch22fits inside and is rotatable in nesting chamber77as best shown inFIG. 2. Friction plate38includes a drive lug80,FIG. 5, that projects through the lost motion slots60and78when the cable drive assembly10is put together.

Front and rear cables82,84shown partially inFIG. 1, are anchored in drums26and30respectively and wound in opposite circumferential directions around the respective drums26and30. Cables82and84extend from the respective drums26and30in the opposite tangential directions and out respective chutes85and87of housing14. In operation, front cable82wraps onto front drum26while rear cable84unwraps from rear drum30and vice-versa.

Cable drive assembly10operates in the following manner.

The front cable82extends from the front cable groove of drum26to a sliding door bracket (not shown) in a position to be wound onto the drum26and into the front cable groove54in response to drum26and front cable groove54rotation about the longitudinal axis21in a forward direction (clockwise as shown inFIG. 1) which closes the sliding door of the van (not shown). When the drum26and front cable groove54rotate in a reverse or counterclockwise direction, opposite the forward direction to open the sliding door, the front cable82winds off of the drum26and out of the front cable groove54.

Similarly, the rear cable84extends from the rear cable groove70to the sliding door bracket (not shown) in a position to be wound off of the drum30from the rear cable groove70in response to drum30and rear cable groove70rotation about the longitudinal axis21in the forward or clockwise direction which closes the sliding door. When the drum30and rear cable groove70rotate in the reverse or counterclockwise direction to open the sliding door, the rear cable84winds onto the drum30into the rear cable groove28.

As shown inFIG. 1, electric motor16is drivingly connected to the input member44of electromagnetic clutch22. For closure, electric motor16is energized to drive output shaft20and input member44connected to it in the forward direction, i.e. clockwise. At the same time electromagnetic clutch22is energized so that input member44drives friction plate38. Friction plate38in turn rotates drum26and its cable groove54in the forward or clockwise direction when drive lug80, after taking up any lost motion, engages the left end of lost motion slot60shown infigure 1. Clockwise rotation about the longitudinal axis21winds front cable82onto drum26to close the sliding door (not shown). As drum26is driven clockwise, spring tab64drives drum30clockwise via tension spring28, winding rear cable84off of drum30and out of cable groove70; with drum30being biased counterclockwise by tension spring28to maintain tension in cables82and84.

When the sliding door of the van door is closed, electric motor16and electromagnetic clutch22are deenergized through a suitable control (not shown) that receives input signals from the optical scanner42.

To open the sliding door (not shown), electric motor16and electromagnetic clutch22are energized to drive output shaft20and friction plate38in the rearward direction, i.e. counterclockwise. Friction plate38in turn rotates the rear drum30and its cable groove70in the rearward or counterclockwise direction when drive lug80, after taking up any lost motion, engages the right end of lost motion slot78shown inFIG. 1. Counterclockwise rotation about the longitudinal axis21winds rear cable84onto drum30to open the sliding door (not shown). As drum30is driven counterclockwise, tension spring63and spring tab64drive front drum26counterclockwise winding front cable82out of cable groove54and off of drum26; with drum26being biased clockwise by tension spring28to maintain tension in cables82and84.

The decreasing cam portion56of front drum26serves to increase the tensile force in the cable to a level that is sufficient to overcome the opposing load created by the door seals during the final closing operation. Decreasing cam portion56is elliptical to increase cable life.

This 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'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.