Abstract:
A brake system for an elevator car wherein only authorized elevator personnel shall have access to the brake release. The system includes a self locking device for maintaining the brake system locked and therefore rendering the elevator car inoperative to passengers until authorized personnel unlock the system.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to elevator braking systems and more particularly to a self locking assembly for elevator braking systems.  
       BACKGROUND OF THE INVENTION  
       [0002]     In certain instances, an elevator car may be caused to stop between building floors due to power failure, for example, whereupon it may be necessary to lock the elevator brake to allow the exit of any passengers. It is important that elevator brake system remain in a locked condition unavailable to release by the general public.  
         [0003]     It has been proposed, in elevators that use a cable brake release system actuated by a handle to make the handle removable and lock the handle with a padlock, for example, to prevent the general public from releasing the brake. In such a system, the handle may be left in place allowing the car to be moved; the handle may be misplaced or lost; or the padlock misplaced during the time the elevator system was being serviced.  
         [0004]     It is an object of the present invention to produce a brake release system for elevator systems that is accessible only by trained elevator personnel.  
         [0005]     Another object of the invention is to produce a self locking elevator braking system including a brake handle wherein a key is needed to release the brake handle and will automatically lock the handle against movement before the elevator mechanic leaves the vicinity of the locking system.  
       SUMMARY OF THE INVENTION  
       [0006]     Other objectives and advantages of the invention may typically be achieved by a self locking elevator brake comprising: an elevator drive brake element rotatable between a brake reset position and a brake released position; a handle attached to said brake element for moving between a locked position wherein said brake element is in said brake reset position and an unlocked position wherein said brake element is in said brake released position, said handle having a latch receiving aperture formed therein; and a selectively operated locking means for maintaining said handle in said locked position, said locking means including a latching plunger releasably engaging said latch receiving aperture when said handle is in said locked position. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The above objects and advantages of the invention will become readily apparent to those skilled in the art from reading the following detailed description of a preferred embodiment of the invention when considered in the light of the accompanying drawings, in which:  
         [0008]      FIG. 1  is a schematic perspective view of a portion of a self locking elevator braking system incorporating the features of the present invention;  
         [0009]      FIG. 2  is a front elevational view of the braking system illustrated in  FIG. 1 ;  
         [0010]      FIG. 3  is a fragmentary side view of the handle illustrated in  FIGS. 1 and 2 ;  
         [0011]      FIG. 4  is a fragmentary top plan view of the latching mechanism illustrated in  FIGS. 1 and 2  and an associated actuating key; and  
         [0012]      FIG. 5  is a top plan view of the latching mechanism illustrated in  FIG. 4  showing a safety switch and the handle illustrated in  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]     Referring to the drawings, there is illustrated a self locking elevator brake actuating element  10  including an elongate handle  12  having one end affixed to a brake element such as a drum  14  mounted to rotate about an axis  16 . The drum  14  is an integral portion of the elevator car drive braking system which may be in the form of the system illustrated and described in U.S. Pat. No. 5,971,109, for example. The handle  12  is provided with a latch receiving aperture  18 , as clearly shown in  FIG. 3 .  
         [0014]     Normally, the handle  12  is in a locked position within a lock assembly  20  as illustrated in  FIGS. 1 and 2 . In this position of the handle  12 , the drum  14  is in a reset position permitting the drive to move the elevator car as long as the drive brake (not shown) is not engaged. The lock assembly  20  includes a main housing securely mounted to a fixed surface  22 , such as a cabinet or wall in the elevator control closet, for example. The lock assembly  20  includes a recess  24  for receiving a portion of the handle  12  in the region of the latch receiving aperture  18 . The lock assembly  20  further includes a latching system similar in principle and structure to a standard residential or commercial door latch mechanism. In the illustrated embodiment, the latching system includes a latching plunger  26  which is normally spring biased to a closed position as clearly illustrated in  FIG. 4 . The latching plunger  26  is caused to be cammed inwardly toward an open position against the bias of a locking spring, not shown, by the camming action of the leading edge of the handle  12 . When the outermost end of the latching plunger  26  becomes aligned with the aperture  18  of the handle  12 , the latching plunger  26  is forced to its closed and locked position. The handle  12  thereupon is immobilized and locked in position and will remain in such condition until an authorized attendant inserts a key  28  into a lock cylinder  30  of the lock assembly  20  and properly unlocks the lock assembly  20  to allow the plunger  26  to be withdrawn from the locking position in the latch receiving aperture  18  of the handle  12 . When the handle  12  is moved out of the recess  24 , the drum  14  is rotated to a brake released position to release the drive brake and permit movement of the elevator car.  
         [0015]     It will be appreciated that with the illustrated embodiment of the invention, a safety switch contact  32  may be mounted within the recess  24  as illustrated in  FIG. 5 . The safety switch contact  32  is actuated by engagement with the handle  12  in the locked position as shown in  FIG. 5  to permit operation of the elevator drive. When the handle  12  is moved out of the recess  24 , the safety switch contact  32  is effective to switch off the power to the elevator car drive system and will not allow the car to run other than by hand operation until the handle  12  is returned to the closed and locked position.  
         [0016]     Further, in order to facilitate the depression of the plunger  26 , a leading edge  34  of the handle  12  may be rounded or beveled to assist in camming the plunger  26  and causing the same to slide against the bias of an operating spring.  
         [0017]     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 understood that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.