Abstract:
A door panel position control mechanism for a multiple panel horizontal sliding door assembly of a freight elevator landing. The mechanism comprises a multiple node scissors linkage that is configured to be easily installed and initially adjusted and which has its parts symmetrically balanced about a vertical plane such that excessive eccentric loading on the components is reduced and a long service life is obtained with reduced wear and a reduced need for periodic adjustment.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to improvements in elevator landing door assemblies and, more particularly, to a position control mechanism for multiple horizontal sliding door panels.  
       PRIOR ART  
       [0002]     Freight elevator landing doors of the multiple panel, horizontal sliding type typically have a device to produce simultaneous movement of the panels. A common type of control device uses a cable and pulley system to produce the desired movement rate and distance which, as between the panels are-typically different but proportional.  
         [0003]     Conventional cable systems are prone to go out of adjustment due to permanent stretching of the cables and/or wear of related parts. Generally, the cable systems are disposed above the door panels thereby making their original installation as well as subsequent service adjustments awkward, tedious and time-consuming.  
       SUMMARY OF THE INVENTION  
       [0004]     The invention provides a multi-panel motion control system for a freight elevator door landing having a simplified linkage arrangement that is easy to install, requires minimal initial adjustment, and is resistant to wear or other distortion effects that require periodic adjustment or replacement. The linkage of the invention is adapted to be mounted at mid-height on the door panels so that it can be easily installed and adjusted by a technician conveniently working on the level of the respective landing.  
         [0005]     Preferably, the linkage is in a multiple scissors or X-like configuration so that the forces on individual links and pivot connections or pins are balanced and relatively low forces are imposed on the linkage. Consequently, the linkage has the potential of operating over an extended service life with a minimum of wear, and thereby reduces the need for periodic service adjustment or replacement. Mounting brackets for the linkage can be directly secured to the panels and minimum initial adjustment is required. While a pinching hazard at the linkage is remote because in operation the linkage is ordinarily shielded by the elevator car door, the mechanism can include shields to minimize the risk of personal injury or mechanical damage when the linkage is exposed during periodic inspection or maintenance. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is an elevational view from the inside of the elevator shaft of a door position control system constructed in accordance with the invention shown with associated door panels in a closed position;  
         [0007]      FIG. 2  is a view similar to  FIG. 1 , with the door panels and position control system in an open position;  
         [0008]      FIG. 3  is an elevational edge view of the control system and door panels from a vantage point lateral of the shaft opening; and  
         [0009]      FIG. 4  is a plan view of the door control system and door panels in an open position. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0010]     An assembly  10  of horizontal sliding door panels  11   a - 11   c,  is illustrated in the figures. The panels  11 , for example, represent the right side of a six-panel door assembly. The left side of the assembly is symmetrical with and a mirror image of  FIGS. 1 and 2 . The panels  11  are supported on traction rollers  12  supported on overhead tracks  13  in a generally conventional manner.  
         [0011]     The door panel assembly  10 , as is typical, exists to close the shaft opening at a respective landing when an elevator car is elsewhere and opens for ingress and egress to the car when the car is present at the landing. The panels  11 , as seen most clearly in  FIGS. 3 and 4 , are horizontally spaced or in staggered vertical planes so that they are able to register one behind the other as shown in  FIG. 4  when in the open position.  
         [0012]     When the panels  11  move between their respective open and closed positions, it is desirable that they all depart from and arrive at these positions at the same time. It follows that the inner door  11   a,  i.e. the door that is spaced farthest from the shaft wall, must move the farthest and, therefore, the fastest, from and towards the center line of the shaft opening (or if the entire door assembly comprises only three panels, to the opposite side of the opening). The position and rate of travel of the door panels  11  in accordance with the present invention, is controlled by a linkage assembly or system  16 . The assembly  16  comprises a series of individual links pivotally connected to one another, to the panels  11 , and to a fixed referenced member or end bracket  17 . The links  18 ,  19  are substantially uniform in length being either a short length or a long length, respectively, the latter being substantially equal to twice the short length. The short length links  18  have operative pivot connections only at their ends, while the long length links  19  have operative pivot connections at their ends-and at their mid-lengths so that they form an X or scissors-like configuration with other links  19 . As shown, the links  18 ,  19  are proportioned so that in relation to the width of the door panels  11  such that when the panels are in the closed position of  FIG. 1 , they are inclined from the horizontal by a substantial angle preferably at least about 30° so that high compressive forces along the axis of the links are avoided and the linkage  16  operates smoothly. The door panel  11   c,  at the right in  FIG. 1 , i.e. the door required to move the least distance between open and closed positions, is referred to as the slow door panel; the door panel  11   a  at the left in  FIG. 1 , i.e. the door panel required to move the greatest distance between open and closed positions, is referred to as the fast door panel; and the door panel  11   b,  in between, is referred to as the middle door panel.  
         [0013]     The linkage assembly  16  comprises a series of nodes  21 - 23  corresponding to the number of sliding door panels it controls. The nodes  21 ,  23  associated with the slow and fast doors, respectively, comprise short links  18  and portions of long links  19 , while the intermediate or middle panel  11   b  has its node comprised of portions of long links  19 .  
         [0014]     The end bracket  17  provides a fixed reference point for the linkage system  16 . The bracket  17  is fixed by bolts to a rigid strut  24  or other stationary member spaced laterally of the landing-opening. The slow and middle door panels  11   c,    11   b,  have associated L-shaped brackets  26 ,  27 , as viewed in the plan view of  FIG. 4 , screwed to vertical edges  28  of their respective door panels. The fast door panel  11   a  has a bracket  29  attached to its side facing the shaft. This fast door panel bracket  29  carrying a pivot pin  30  is horizontally adjustable on the panel  11   a  by virtue of slots  31  receiving screws attaching it to the panel. At the other end of the linkage  16 , a pivot pin  32  in the form of a shoulder bolt, is horizontally adjustable in a slot  33  in the bracket  17 . The slow and middle door panel brackets  26 ,  27  support pivot pins  35 .  
         [0015]     As shown in  FIGS. 1 and 2 , the ends of the links remote from the bracket pins  30 ,  32 ,  35 , are each pivotally connected to one or two link ends by common pins. The links  18 ,  19  are assembled on the bracket pins  30 ,  32 ,  35  and, as shown in  FIG. 4 , the pins are arranged to support the links in three closely spaced parallel, vertical planes. Alternate links are doubled (going from left or right in  FIGS. 1 and 2 , above or below the bracket pins) to straddle intervening single links. This straddling of intervening single links with double links tends to balance the operating forces on the links and pins and, thereby, avoids excessive eccentric loading on the parts and wear which would otherwise be attendant to such eccentric loading.  
         [0016]     The slow, middle and end brackets  26 ,  27  and  17 , are configured with pivot pin-supporting legs  36 ,  37 ,  38  that lie generally in a common vertical plane with the bracket  29  parallel to the door panels  11 . To accomplish this, the slow and middle brackets  26 ,  27 , have legs  41 ,  42  perpendicular to these pin supporting legs  36 ,  37  of different lengths, each sufficient to reach the edges of their respective door panels to which they are attached by suitable screws. Additionally, the pivot pin supporting legs  36 ,  37  are U-shaped so that the end bracket leg  38  can nest in the slow bracket leg  36 , and the slow bracket leg  36  can nest in the middle bracket leg  37 .  
         [0017]     It can be seen that the pivot pin supporting bracket  29  on the fast door panel  11   a  is horizontally adjustable with slots  31  that accept screws that fix it to this door panel. The horizontal adjustability of the shoulder bolt  32  on the end bracket  17  and the fast bracket  29  enables the linkage  16  to be adjusted so that in the open position, the door panels  11  can be aligned with the landing opening frame.  
         [0018]     A set of guards  46  is mounted on the linkage  16  to reduce the already limited risk that a serviceman&#39;s hand or tools might be pinched between the links  18 ,  19  when the door panels are being opened. The guards can be in the form of sheet metal or plastic strips that are assembled on pivot pins  47  coupling the ends of the links remote from the bracket pins  30 ,  32 ,  35 . The guards  46  are U-shaped when viewed from the edge in  FIG. 3 . This U-shaped-configuration, with both vertical parts of the guard  46  pivoted on a respective pin  47 , allows the guard to be relatively stiff so that it remains in a vertical plane. The illustrated curved profiles of the brackets  17 ,  26  and  27  also reduce the risk of a pinching hazard.  
         [0019]     It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.