Abstract:
A retractable safety edge mechanism includes a safety edge for projecting ahead of a leading edge of a door, a link attached to the safety edge for pivotal fixation to the door, a lever mechanism for pivotal fixation to the door; and switch means disposed on one or both of the link and the lever mechanism operable by relative movement therebetween. Rotation of the lever mechanism in a retraction direction causes rotation of the link to retract the extended safety edge and the lever mechanism projects ahead of the safety edge. The safety edge mechanism may be incorporated into a powered door system.

Description:
[0001]     The invention relates to the field of automatically operated sliding doors and, in particular, to a retractable safety edge mechanism for mounting on such a door, a method for installing the retractable safety edge mechanism on the door and the resultant door system obtained.  
       BACKGROUND OF THE INVENTION  
       [0002]     A conventional sliding door retractable safety edge mechanism generally includes a safety edge pivotally supported by links which in turn are rotatably mounted to the door so that the safety edge is parallel to, and projects ahead of, a leading edge of the door. In such an arrangement, if the safety edge encounters any obstruction during a dosing operation of the door it retracts and thereby the links are simultaneously rotated. This retraction of the safety edge or rotation of the support links is detected by switch means which immediately signals the halting, and preferably reopening, of the door.  
         [0003]     It is often necessary to retract the safety edge when the door nears its fully closed position. For example, in the case of two center-opening doors it is clearly desirable to retract the safety edges so that they will not be deformed by continually bumping against each other as the doors fully close. JP-02225287-A describes a frequently used retractable safety edge mechanism that protects objects during the closing operation of the door and also retracts the safety edge when the door approaches its fully closed position. A fulcrum fixed to the door rotatably supports not only one of the links attached to the safety edge, but also a lever which is biased in an extended direction. The switch means which is provided on the link and/or the lever is operable by relative rotation therebetween. Rotation of the lever in a retraction direction causes simultaneous rotation of the link to retract the extended safety edge. The mechanism of JP-02225287-A also includes a linkage arm which, at one end, is pivotally mounted to a stationary part of the door surround and, at the other end, is pivotally mounted to the door in close proximity to the fulcrum carrying the lever and link. As the door approaches its fully closed position, the linkage arm assumes a position where a cam thereon engages the lever causing simultaneous rotation of the lever and the link in the retraction direction and thereby the safety edge is retracted.  
         [0004]     The linkage arm is connected to and therefore adds weight to the door. Since the maximum kinetic energy of the sliding door is restricted by regulation (see for example European Standard EN 81-1:1998, §8.7.2.1.1.2 which limits the kinetic energy to 10 J), this additional weight from the linkage arm effectively reduces the maximum permissible closing speed of the door. Furthermore, the linkage arm increases both the initial and the maintenance costs of the door.  
         [0005]     Moreover, the function of the linkage arm is essentially distance dependent as it travels with, and spans the entire path of, the door to retract the safety edge as the door approaches its fully closed position. The linkage arm assumes its active state only when the door is at a specific position along its travel path. Hence, a given linkage arm can only be used on doors having the same travel path. Accordingly, doors systems having different travel paths require different linkage arms.  
         [0006]     Accordingly, an objective of the present invention is to overcome the problems associated with the prior art in particular, the invention seeks to reduce the number of components in a retractable safety edge mechanism without deteriorating its functionality so as to simplify installation and reduce weight, cost and complexity. Furthermore, the invention seeks to provide a retractable safety edge mechanism which can be universally applied to door systems used to close openings of different widths.  
         [0007]     These objectives are achieved by a retractable safety edge mechanism according to the invention, a powered door system incorporating the retractable safety edge mechanism and a method for installing the retractable safety edge mechanism in a powered door system.  
       BRIEF DESCRIPTION OF THE INVENTION  
       [0008]     A retractable safety edge mechanism for use on a powered door system in accordance with the present invention comprises a safety edge for projecting ahead of a leading edge of a door, a link attached to the safety edge for pivotal fixation to the door, a lever mechanism for pivotal fixation to the door, and switch means disposed on one or both of the link and the lever mechanism operable by relative movement therebetween wherein rotation of the lever mechanism in a retraction direction causes rotation of the link to retract the extended safety edge, characterized in that the lever mechanism projects ahead of the safety edge.  
         [0009]     Accordingly, as the door approaches its closed position, the lever mechanism which extends ahead of the safety edge will abut a door jamb (or alternatively a similar lever mounted on an opposing door of a center-opening door system) such that further movement of the door in the closing direction will cause the lever mechanism to rotate in the retraction direction thereby effecting simultaneous rotation of the link and retraction of the extended safety edge. Furthermore, if the safety edge engages with an obstruction during a closing operation of the door, the link rotates independently of the lever mechanism in the retraction direction to operate the switch means.  
         [0010]     The retractable safety edge mechanism according to the invention commences retraction of the safety edge when the leading edge of the door reaches a specific distance from its fully closed position. That specific distance is defined by the amount to which the lever mechanism projects ahead of the leading edge. Hence, the retractable safety edge mechanism will operate effectively irrespective of the total travel path of the door, and therefore can be universally applied to door systems having different travel paths.  
         [0011]     Preferably, the link and the lever mechanism are pivotally mounted alongside each other on a common fulcrum. Alternatively, the link can be mounted on a first fulcrum and the lever mechanism can be disposed above the link on a second fulcrum. With such an arrangement, the link and lever mechanism are in the same vertical plane enabling a reduction in the width of the retractable safety edge mechanism.  
         [0012]     Preferably, the retractable safety edge mechanism includes a mounting plate on which the link and lever mechanism are pivotally mounted. Accordingly, the components of the retractable safety edge mechanism can be pre-mounted on the mounting plate at a factory making on site installation easier.  
         [0013]     Preferably, the retractable safety edge mechanism further comprises a bracket for fixation to a stationary part of the door system and for abutment against the lever mechanism as the door approaches its fully opened position. Hence, when the door approaches the fully opened position, the bracket engages the lever mechanism such that further movement of the door in the opening direction will cause the lever mechanism to rotate in the retraction direction thereby effecting simultaneous rotation of the linkage and retraction of the extended safety edge.  
         [0014]     The horizontal length of the bracket depends on the width of the panel(s) used in the door. Clearly, the bracket can be supplied with a specific length for a door having a specific panel width, however, preferably the bracket is horizontally adjustable so that the one bracket can be used for all conceivable door systems.  
         [0015]     Preferably, a portion of the lever mechanism that projects ahead of the safety edge is positioned above the safety edge. Accordingly, the safety edge and the lever can be located in the same plane (saving space) without adversely affecting their respective functionality.  
         [0016]     Preferably, in a powered door system incorporating the retractable safety edge mechanism the portion of the lever mechanism that projects ahead of the safety edge is contained within or above a door transom. Hence, the lever mechanism does not obstruct the opening and is not visible to people passing through the opening. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The present invention is herein described by way of specific examples with reference to the accompanying drawings in which:  
         [0018]      FIG. 1  is a perspective view of a center-opening door system having doors incorporating retractable safety edge mechanisms according to a first embodiment of the invention;  
         [0019]      FIG. 2  is a plan view of the components of the retractable safety edge mechanisms illustrated in  FIG. 1 ;  
         [0020]      FIG. 3  is an exploded view of section A of  FIG. 2  illustrating the main components of the retractable safety edge mechanism in more detail;  
         [0021]      FIG. 4  is a partial view of the retractable safety edge mechanism of  FIG. 3  with the door in the fully opened position;  
         [0022]      FIG. 5  is a partial view of the retractable safety edge mechanism of  FIG. 3  as the door moves to an intermediate position along its travel path;  
         [0023]      FIG. 6  is a view similar to  FIG. 5  except it illustrates the situation when the safety edge encounters an obstruction during the closing operation of the door;  
         [0024]      FIG. 7  is a partial view of the retractable safety edge mechanism of  FIG. 3  with the door in the fully closed position;  
         [0025]      FIG. 8  is a partial view of a retractable safety edge mechanism according to a second embodiment of the invention as the door moves to an intermediate position along its travel path;  
         [0026]      FIG. 9  is a partial view of a retractable safety edge mechanism according to a third embodiment of the invention; and  
         [0027]      FIG. 10  is a partial view of a retractable safety edge mechanism according to a fourth embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]      FIG. 1  illustrates a center-opening door system  100  commonly used in modern elevator installations. The door system  100  comprises a left and a right door  102   a ,  102   b  respectively which for simplicity have each been shown as consisting of a single panel. It will be readily appreciated that the invention is not limited to such a construction as it can be used equally effectively on multi-panel doors and in telescopic rather than centre-opening door systems. The doors  102   a ,  102   b  are suspended in a conventional manner by hangers  104  from a door track  106 . The hangers  104  are connected to a transmission belt  108  which is driven by a motor  110  to move the door panels  102   a ,  102   b  in opposing directions. The function of the motor  110  is governed by a door controller  114 . The track  106 , hangers  104 , transmission belt  108 , motor  110  and controller  114  are generally invisible to passengers as they are all contained within or above a door transom  112  defining the uppermost part of a doorway. A retractable safety edge mechanism  1  according to the present invention is provided for each of the doors  102   a ,  102   b.    
         [0029]     The retractable safety edge mechanisms  1  are shown in more detail in  FIG. 2 , however, so as to avoid unnecessary repetition, the following description refers to the components, construction and function of only one of the retractable safety edge mechanisms  1  (the other being identical). The retractable safety edge mechanism  1  includes a safety edge  2  configured to extend substantially the full length of the door  102   a ,  102   b  and to project ahead of the leading edge of the door  102   a ,  102   b . The safety edge  2  is supported by means of pivots  14 , 34  on a pair of links, the upper link being designated  8  and the lower link  28 . These support links  8 , 28 , in turn, are rotatably mounted on fulcrums  16 , 36  provided on mounting plates  18 , 38 , which in use are secured to the door  102   a ,  102   b  using any conventional fastening technique. A retraction lever  22  is also pivotally mounted on the fulcrum  16  of the upper link  8 . As can be clearly seen from the figure, a protruding end  23  of the retraction lever  22  extends above and ahead of the safety edge  2 .  
         [0030]     The retractable safety edge mechanism  1  also includes a bracket  40  having a vertical support  42  which in use is secured to the door transom  112  as shown in  FIG. 1 , and a horizontal abutment  44 . Preferably the abutment  44  is extensible in the horizontal direction x and includes a bumper  46  secured to an end facing the safety edge  2 . The bumper  46  can be manufactured from a sound and vibration absorbing material such as rubber.  
         [0031]      FIG. 3  is an exploded view of section A of  FIG. 2  illustrating in greater detail the upper mounting plate  18  and the components of the retractable safety edge mechanism  1  attached thereto. The fulcrum  16  is inserted through a hole  19  provided in the mounting plate  18  so that a head of the fulcrum  16  abuts a rear surface of the mounting plate  18 . The retraction lever  22  and the upper support link  8  are mounted, by way of corresponding holes  25 , 9  provided therein, on the fulcrum  16 . The retraction lever  22  and the upper support link  8  are retained on, and prevented from axial movement along, the fulcrum  16  by a circlip  17 . The upper mounting plate  18  also supports two stoppers  20 ,  21  which limit rotation of the retraction lever  22  and the upper support link  8  about the fulcrum  16  in an extension direction E and a retraction direction R, respectively.  
         [0032]     The retraction lever  22  includes a protruding end  23  positioned above and extending ahead of the safety edge  2 , a stopper  24  mounted in close proximity to an end remote to the protruding end  23 , and a magnet  26  suspended underneath the retraction lever  22 . The upper support link  8  includes the pivot  14  on which the safety edge  2  is mounted, a chamfered end  10  remote from the pivot  14  for engagement with the stopper  24  mounted on the retraction lever  22 , and a magnetically operable contact switch  12  suspended underneath the link  8 . The safety edge  2  comprises a rigid support channel  6  having a hole  7  into which the pivot  14  on the link  8  is inserted, and a deformable member  4  positioned ahead of the rigid support channel  6  for impacting with an object obstructing the path of the closing door  102   a.    
         [0033]     The center of gravity of the retraction lever  22  lies between its mounting hole  25  and the protruding end  23  (or to the right of the fulcrum  16  as shown in the FIG.). Accordingly, with no external forces acting on the retraction lever  22 , gravitational force biases the lever  22  in the extension direction E to its rest position where it abuts against the upper stopper  20  on the mounting plate  18 . Similarly, the weight of the safety edge  2  pivotally mounted on the support link  8  biases the link  8  in the extension direction E to its rest position where the chamfered end  10  abuts against the stop  24  on the retraction lever  22 . In their respective rest positions, the lever  22  and the link  8  lie alongside each other as do the magnet  26  and the contact switch  12 . This alignment of the magnet  26  with the contact switch  12  maintains the switch  12  in an ON state. In use, the contact switch  12  is connected by means of a conventional cable (not shown) to the door controller  114 .  
         [0034]     FIGS.  4  to  7  illustrate all the operating conditions and positions that the retractable safety mechanism  1  undergoes in use.  FIG. 4  illustrates the retractable safety edge mechanism  1  with the door  102   a  at its fully opened position. As the door  102   a  moves to this position, the bumper  46  mounted on the horizontal abutment  44  of the bracket  40  engages with the stop  24  mounted on the retraction lever  22  (or alternatively, the bumper  46  can be positioned for direct engagement with the retraction lever  22 ) causing simultaneous rotation of the lever  22  and the support link  8  in the retraction direction R about the fulcrum  16 . Since there is no relative rotation between the lever  22  and the link  8 , the magnet  26  and the contact switch  12  remain in alignment during this operation and therefore the switch  12  remains ON. Thereby, the safety edge  2  is retracted without the switch  12  signalling the door controller  114  to halt or reverse the motor  110 .  
         [0035]      FIG. 5  illustrates the retractable safety edge mechanism  1  with the door  102   a  in an intermediate position. In this position, no external forces act of the retractable safety edge mechanism  1  and thus both the retraction lever  22  and the support link  8  are at their rest positions with the lever  22  abutting the upper stopper  20  mounted on the mounting plate  18  and the chamfered end  10  of the support link  8  resting against the stop  24  of the retraction lever  22 . Here again, there is no relative rotation between the lever  22  and the link  8  and therefore the contact switch  12  remains ON permitting normal operation of the controller  114 .  
         [0036]      FIG. 6  illustrates the retractable safety edge mechanism  1  when the safety edge  2  comes into contact with an obstruction, represented by a force F, during a closing operation of the door  102   a . The force F acting on the safety edge is translated into rotation of the support link  8  in the retraction direction R about the fulcrum  16 . However, the retraction lever  22  remains in its rest position in abutment against the upper stopper  20  mounted on the mounting plate  18 . This relative rotation between the link  8  and the lever  22  brings the magnet  26  and the contact switch  12  out of alignment with the switch thereby sending an OFF signal to the door controller  114  which immediately halts or reverses the operation of motor  110 . Accordingly, the door  102   a  is stopped or re-opened to prevent further movement against the obstruction.  
         [0037]      FIG. 7  illustrates the retractable safety edge mechanism  1  with the door  102   a  at its fully closed position. As the door  102   a  approaches this position (as shown in  FIG. 2 ), the protruding end  23  of the retraction lever  22  comes into contact with the corresponding protruding end of the retraction lever mounted on the opposing door  102   b . This causes simultaneous rotation of the lever  22  and the link  8  in the retraction direction R. Since there is no relative rotation between the lever  22  and the link  8 , the magnet  26  and the contact switch  12  remain in alignment during this operation and therefore the switch  12  remains ON. Thereby, the safety edge  2  is retracted without the switch  12  signalling the door controller  114  to halt or reverse the motor  110 .  
         [0038]     The skilled person will appreciate that many different variations are possible to achieve the same objective. For example, any lever mechanism can be used in place of the retraction lever  22  so long as it is capable of translating a horizontal force exerted on the protruding end  23  into a rotation of the link  8  about the fulcrum  16  in the retraction direction R to retract the safety edge  2 . Such an example is given in  FIG. 8  which illustrates a partial view of a retractable safety edge mechanism  200  according to a second embodiment of the invention. The figure generally corresponds with  FIG. 5  in that it shows the retractable safety edge mechanism  200  with the door  102   a  in an intermediate position. However, instead of having a single lever  22  mounted on the fulcrum  16 , the lever mechanism  122  comprises a first lever  122   a  mounted on the fulcrum  16  and a self-levelling second lever  122   b  mounted on a frictionless pivot  122   c  provided on the first lever  122   a . In the position shown, no external forces act of the retractable safety edge mechanism  200  and thus both the first lever  122   a  and the support link  8  are at their rest positions with the first lever  22  abutting the upper stopper  20  mounted on the mounting plate  18  and the chamfered end  10  of the support link  8  resting against the stop  24  of first lever  22 . As the door  102   a  approaches the fully closed position, the protruding end  23  of the self-levelling second lever  122   b  comes into contact with the corresponding protruding end of the retraction lever mounted on the opposing door  102   b . Although the second lever  122   b  remains substantially horizontal during further movement of the door  102   a  in the closing direction, it transmits horizontal force through the pivot  122   c  to the first lever  122   a  causing simultaneous rotation of the first lever  122   a  and the support link  8  in the retraction direction R. As in the previous embodiment, the magnet  26  and the contact switch  12  remain in alignment for all operating conditions except for when the safety edge  2  comes into contact with an obstruction during a closing operation of the door  102   a . Here again, the force F representative of the obstruction causes independent rotation of the link  8  in the retraction direction R bringing the magnet  26  and the contact switch  12  out of alignment and causing the door controller  114  to immediately halt or reverse the operation of motor  110 .  
         [0039]      FIG. 9  is a partial view of a retractable safety edge mechanism  300  according to a third embodiment of the invention. Instead of providing the fulcrum  16  at an intermediate along the retraction lever  22  and the support link  8 , the fulcrum  16  of the present embodiment is disposed on the lever  22  at an end remote from the protruding end  23  and on the link  8  at an end remote from the safety edge mounting pivot  14 . In the rest position as shown, no external forces act of the retractable safety edge mechanism  300  and thus both the retraction lever  22  and the support link  8  are at their rest positions with the lever  22  abutting the lower stopper  21  mounted on the mounting plate  18  and the support link  8  resting against a bracket  124  extending from the lever  22  underneath the link  8 . The bracket  124  ensures simultaneous rotation of the lever  22  and the link  8  in the retraction direction R as the door  102   a  approaches its fully closed position. If the safety edge  2  engages with an obstruction during a closing operation of the door  102   a , the link  8  rotates independently of the lever  22  in the retraction direction causing the switch  12  to signal the door controller  114  to immediately haft or reverse the operation of motor  110 . Although the retractable safety edge mechanism  300  of the present embodiment cannot be used to retract the safety edge  2  when the door  102   a  approaches its fully opened position (and therefore the bracket  40  is redundant), the skilled person will appreciate that with minor modification to the lever  22  this function can be accommodated. In particular, if the lever  22  was extended beyond the fulcrum  16  and the link  8  to provide an abutment surface for the bumper  46  on the bracket  40 , then as the door  102   a  approaches its fully opened position, the bumper  46  will engage with the lever  22  causing simultaneous rotation of the lever  22  and the link  8  in the retraction direction R.  
         [0040]     In the previously described embodiments, the lever mechanism  22 , 122  is always disposed alongside the link  8  on the same fulcrum  16 .  FIG. 10  is a partial view of a retractable safety edge mechanism  400  according to a fourth embodiment of the invention wherein the retraction lever  22  is disposed on a second fulcrum  116  above the support link  8  within the same vertical plane. In the rest position as shown, no external forces act of the retractable safety edge mechanism  400  and thus both the retraction lever  22  and the support link  8  are at their rest positions with the lever  22  abutting the upper stopper  20  mounted on the mounting plate  18  and the support link  8  resting against an abutment  224  mounded on the underside of the lever  22 . As the door  102   a  approaches its fully opened position, the bumper  46  mounted on the horizontal abutment  44  of the bracket  40  engages with the retraction lever  22  causing simultaneous movement of the lever  22  and the support link  8  in the retraction direction R about their respective fulcrums  116 , 16 . The same simultaneous movement is exhibited when the door  102   a  approaches its fully closed position. If the safety edge  2  engages with an obstruction during a closing operation of the door  102   a , the link  8  rotates independently of the lever  22  in the retraction direction R. This independent rotation of the link  8  breaks a contact between a switch  212  mounted on the link  8  and a switch operator  226  mounted on the lever  22  causing the switch  12  to signal the door controller  114  to immediately halt or reverse the operation of motor  110 .  
         [0041]     In all of the preferred embodiments described, the lever mechanism  22 , 122  is biased by gravity in the extension direction E. However, it is equally feasible to bias the lever mechanism  22 , 122  using a resilient member such as a spring. Furthermore, as well established by the prior art, a spring can also provided on the link  8  to partially counteract the weight of the safety edge  2 .  
         [0042]     The invention has been specifically described for use on a center-opening door system  100 . However, the skilled person will easily acknowledge that the invention is equally applicable to door systems  100  incorporating a single telescopic door. In such a case, as the door  102   a  approaches its fully closed position (where the leading edge lies next to a doorjamb), the protruding end  23  of the lever mechanism  22 , 122  would abut the door jamb such that further movement of the door in the closing direction will cause simultaneous rotation of the lever mechanism  22 , 122  and link  8  to retract the safety edge  2 .  
         [0043]     Instead of mounting the lever mechanism  22 , 122  for engagement with the upper support link  8 , it is technically feasible (although not as practical) to mount the lever mechanism  22 , 122  on the lower mounting plate  38  for engagement with the lower support link  28 .