Abstract:
A door system includes a reel, a door interconnect at a first end to the reel for winding and unwinding thereupon and one or more guide channels. The reel is rotatably mounted on a lever which is pivotally mounted to a pivot axis. Thus, the reel can pivot about the pivot axis to ensure that, during operation, a point at which an outer layer of the door engages/disengages with the penultimate door layer remains in the same general location with respect to the guide channels and accordingly, an angle (if any) at which the door enters the guide channels remains constant throughout operation of the door system.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to doors systems and, in particular, to an elevator door system comprising a door that is wound upon a vertical axis during an opening operation.  
         [0002]     Such elevator door systems are well known from the prior art and are described, for example, in WO-A2-2005/070807 and WO-A2-2005/070808. Each elevator door is generally formed from a stainless steel sheet or interconnected vertical rigid panels, typically manufactured from a metal. In operation, as the elevator door is opened and closed it is guided across the entrance in guide channels, typically located above and below the entrance to which access is to be controlled by the door system. The plurality of panels or the sheet is wound onto and unwound from a vertical axis in the form of a motorized reel whereby the driving force from the motor is transmitted through the reel and onto the door to provide lateral movement thereof.  
         [0003]     As the door is wound and unwound, the diameter at which the outer layer of the door circumscribes the vertical axis continually changes. Accordingly, the angle at which the tangent of the outer layer intersects the plane of the guide channels continually changes. Therefore, during operation the door enters the guide channels at different angles.  
         [0004]     If the door enters the guide channels at an angle, the sudden change in its direction causes localized stress on both the door itself and the guide channels. This results in the production of unwanted noise, especially if the door is composed of interconnected vertical panels, and will damage the aesthetic appearance, and eventually the structure, of the door. These problems are amplified in the prior art since said angle continually changes during operation.  
       SUMMARY OF THE INVENTION  
       [0005]     An objective of the present invention is to improve the operation of the door system and thereby to reduce the stress on the door and the guide channels at the point here the door enters the guide channels. In so doing, the present invention drastically reduces the noise generated during operation thereby improving passenger comfort and reduces the structural and aesthetic damage to the door and guide channels which inherently reduces the maintenance costs.  
         [0006]     This objective is achieved by a door system comprising a reel, a door interconnect at a first end to the reel for winding and unwinding thereupon and one or more guide channels. The reel is rotatably mounted on a lever which is pivotally mounted to a pivot axis.  
         [0007]     Thus, the reel can pivot about the pivot axis to ensure that, during operation, the point at which the outer layer of the door engages/disengages with the penultimate door layer remains in the same general location with respect to the guide channels and accordingly, the angle (if any) at which the door enters the guide channels remains constant throughout operation.  
         [0008]     Preferably, the pivot axis is inline with a plane defined by the guide channels. Hence, if a force acts on a leading edge of the door, the lever is self-aligning to ensure that the point at which the outer layer of door engages/disengages with the penultimate door layer is always in the plane of the guide channels. Hence, the door smoothly enters the guide channels along the plane thereof without changing direction.  
         [0009]     The door system can further comprise a roller for engaging an outer layer of the door wound upon the reel. Hence, even if the pivot axis is not aligned in the plane defined by the guide channels, the resultant moment of any force acting to the door about the pivot axis can be used to bias the lever towards the roller to ensure that the engagement/disengagement point is always in the plane of the guide channels.  
         [0010]     If the resultant moment about the pivot axis is not sufficient to continually urge the outer layer of the wound door into contact with the roller, resilient means such as a spring can be used to produce the required biasing force on the lever.  
         [0011]     Preferably, the reel is rotatable about a rotation axis and a radius of an outer surface of the reel from the rotation axis gradually increases from a minimum value to a maximum value with a radial step transition therebetween. The height of the radial step is substantially equal to the depth of the door. Accordingly, upon being wound onto the reel, the diameter of the outer layer of the door gradually and smoothly increases without any step transitions which would otherwise cause noise and possibly damage.  
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0012]     The above, as well as other, advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which:  
         [0013]      FIG. 1  is an exploded perspective view an elevator door system according to the present invention;  
         [0014]      FIG. 2  is a cross-section plan view through the reel of the elevator door system of  FIG. 1 ;  
         [0015]      FIG. 3A  is a plan view from above showing the door system of  FIG. 1  in an almost fully open position;  
         [0016]      FIG. 3B  corresponds to  FIG. 3A  but shows the door system in an almost fully closed position; and  
         [0017]      FIG. 4  is similar to  FIG. 3A  but illustrates a second embodiment of the door system according to the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]      FIG. 1  is a general perspective view of an elevator door system  1  according to the present invention incorporating a car door  2  which, in use, is used to control access to an elevator car (not shown) through a doorway from a landing within a building. The door  2  is composed of a plurality of vertically aligned panels  4  each of which is preferably extruded from aluminium for its superior strength to weight ratio. The panels  4  are bound at their upper and lower extremities by flexible belts  6  and guided in upper and lower guide channels  8 . The belts  6  are attached at one end to a reel  10  mounted at one side of the doorway, rotation of which is controlled by a motor  12  to open and close the door  2 . The opposing ends of the belts  6  are attached by cables  14  to a counter-reel  16  which is biased in a door closing direction by a closing weight  18 . The reel  10  and the counter-reel  16  are contained and retained within opposing door jambs (not shown).  
         [0019]     In operation, the door  2  is unwound from the reel  10  and guided along the guide channels  8  under the influence of the biasing force of the closing weight  18 , and optionally by a closing force developed thereon by the motor  12 , to close the doorway. To open the door  2 , the motor  12  provides an opening force to overcome the biasing force of the closing weight  18  and the door  2  is guided along the guide channels  8  and drawn onto the reel  10 .  
         [0020]     If power to the motor  12  is interrupted during operation, the gravitational force acting on the closing weight  18  transmits a force through the counter-reel  16  and the cables  14  which is sufficient to overcome the inertia of both the motor  12  and the door  2  to automatically close the door  2 , thereby ensuring the safety of any passengers.  
         [0021]     The reel  10  has a central axle  20  which is received within corresponding holes provided in an upper and a lower support lever  24 . The central axle  20  defines a rotation axis R about which the reel  10  can rotate to wind and unwind the door. The support levers  24  are mounted on a stationary pivot axis P. The rotation axis R is parallel to but horizontally displaced from the pivot axis P, and accordingly the reel  10  can swing about the pivot axis P.  
         [0022]      FIG. 2  is a cross-section showing in greater detail the reel  10  of the elevator door system  1  of  FIG. 1 . The reel  10  has a profile which generally corresponds to the shape of an apostrophe. In circumscribing the outer surface of the reel  10 , its radius from the rotation axis R gradually increases from a minimum value “r 1 ” to a maximum value “r 2 ” with a radial step transition  22  therebetween. The height (r 2 −r 1 ) of the radial step  22  is substantially equal to a depth “d” of the door  2 . Accordingly, upon being wound onto the reel  10 , the diameter of the outer layer of the door  2  gradually and smoothly increases without any step transitions which would otherwise cause noise and possibly damage.  
         [0023]     The function of the support levers  24  is hereinafter described with reference to  FIGS. 3A and 3B . In particular,  FIG. 3A  shows the door  2  in an almost fully open position with the majority of the door panels  4  having been wound in layers onto the reel  10 . For clarity, the door layers have been drawn with spaces therebetween however in practice it will be readily understood that the door layers are tightly wrapped around the reel  10 .  
         [0024]     The support levers  24  at any given instant during operation of the door system  1  assume a position which produces the least moment about the pivot axis P. Since the rotational force generated by the motor  12  can be neglected as it has no significant effect on the moment of the system  1  about the pivot axis P, the only external force giving rise to the moment is the biasing force exerted by the closing weight  18  on the cables  14  and the door  2 . As shown in  FIG. 3A , the biasing force of the closing weight  18  acts along, and the pivot axis P is positioned in line with a plane of movement of the door  2  extending between the guide channels  8  and consequently, during operation, a point E at which the outer layer of door  2  engages/disengages with the penultimate door layer is always in the plane of the guide channels  8 . Hence, the door  2  is unwound from the reel  10  directly into the plane of the guide channels  8  without making an angle on entry into the guide channels  8 . This smooth operation of the door system  1  reduces the noise generated and damage sustained by the door  2  during operation.  
         [0025]     As the door  2  is unwound from the reel  10  of  FIG. 3A  in a closing operation, the diameter of the outer layer of the door  2  about the reel  10  gradually decreases. However, as discussed above, in order to minimize the moment about the pivot axis P, the engagement/disengagement point E of the door  2  is always in the plane of the guide channels  8 . To satisfy these two conditions, the support lever  24  turns anticlockwise about the pivot axis P as shown in the drawing. Eventually, the door  2  assumes the condition shown in  FIG. 3B  in which it approaches the fully closed position with the majority of the door panels  4  having been unwound from the reel  10 .  
         [0026]      FIG. 4  is similar to  FIGS. 3A and 3B  but illustrates an alternative embodiment door system  1 ′ of the present invention. In place of the vertical panels  4  and the belts  6  of the previous embodiment, a door  2 ′ is formed from a sheet of material, preferably stainless steel. Hence, the depth “d” of the door  2 ′ is substantially reduced and it is no so important that the reel  10  has a profile with the radial step  22  to accommodate the depth “d” of the door  2 ′. As can be seen from the drawing, a reel  10 ′ has a circular profile and the door  2 ′ is attached thereto by a strap  30 . The door system  1 ′ incorporates a closed-loop force transmission system, as described in the co-pending European Patent Application No. 05109847.3, and the tension of the closed-loop force transmission system effectively acts on opposing sides of the wound door  2 ′. Accordingly, it is more difficult in this arrangement to rely on the cancellation of the moment about the pivot axis P to ensure that the engagement/disengagement point E is in the plane of the guide channels  8 . Instead, the resultant moment about the pivot axis P tends to bias the support lever  24  counter-clockwise. Movement in this direction is restricted by a roller  26 , which ensures that the engagement/disengagement point E is always in the plane of the guide channels  8 .  
         [0027]     Although the pivot axis P is shown in the plane of the guide channels  8 , it need not be in this position. Indeed, instead of using the resultant moment about the pivot axis P to urge the outer layer of the wound door  2 ′ into contact with the roller  26 , a spring  28  can be used for this function.  
         [0028]     It will be readily understood that specific features of the described embodiments can be interchanged to give further embodiments according to the present invention. For example, if for some reason it is not possible to position the pivot axis P of the first embodiment of the present invention in line with the plane of the guide channels  8 , the roller  26 , and optionally the spring  28 , of the second embodiment can be incorporated to ensure that the engagement/disengagement point E is always in the plane of the guide channels  8 .  
         [0029]     Furthermore, although the present invention has been described with particular reference to its application in an automatic elevator door system, it can be applied to any automatic or manual door system.  
         [0030]     Although, the profiled reel  10  of the embodiment shown in  FIGS. 1-3B  has been described specifically with reference to the present invention wherein the rotation axis R of the reel  10  is pivotal about the pivot axis P, it can be used independently of the present invention to improve the performance of a door system in which the rotation axis R is fixed.  
         [0031]     In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.