Abstract:
A brake device has magnets arranged on a frame that is fastened to a bearing pedestal of an elevator drive machine. The frame includes a pair of spaced stabilizers attached to a pair of magnet carriers on which the magnets are fastened. The magnets act on disk armatures arranged on brake arms pivoted on the pedestal. The magnetic forces act in opposition to the spring forces of compression springs and release the brake shoes from a brake drum, the forces which then occur being absorbed by the frame.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a brake device for a drive machine of an elevator, comprising brake arms which are supported in swiveling manner on a bearing pedestal and have brake shoes which act on a brake drum, the brake arms being guided at their free ends by means of a fixed guide element and pressed against by compression springs acting in the direction of the guide element, magnets being provided which act in opposition to the compression springs to release the brake shoes.  
           [0002]    European patent specification EP 0 603 644 shows a known brake device having a brake drum that is fastened to a traction sheave and against which brake shoes held in swiveling manner on brake arms rest. The brake arms are arranged at one end to pivot on axles. At the other end, a tie rod is provided which passes through the brake arms, and a compression spring is arranged at each end of the tie rod. The compression spring presses at one end against an end stop of the tie rod, and at the other end against the brake arm. The end stop can be moved by means of an adjusting screw, causing the brake shoe to be pressed to a greater or lesser degree against the brake drum. An actuating bolt passes through the free end of each brake arm. Both actuating bolts are acted on by a force originating in each case from a magnet, and acting in opposition to the spring force of the compression springs, so that the brake shoes are raised from the brake drum.  
           [0003]    A disadvantage of this known brake device is that with brake devices for larger drive machines, the transmission of large braking forces onto the brake drum is not possible without additional measures, for reasons of material deformation. Furthermore, monitoring the position of the brake shoes requires a substantial capital outlay.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention concerns a brake device that provides a solution to avoiding the disadvantages of the known brake devices and creates a brake device with which larger drive units can be reliably braked.  
           [0005]    The advantages achieved by the invention are that with a simple construction of the brake device, and of the bearing pedestal supporting the brake device, a rigid brake device can be made with which, especially, greater braking forces can be transmitted onto the brake drum without problem. Furthermore, the stability of form, and the function, of the brake release system can be improved at the same time as the material outlay and weight are reduced. With the brake device according to the present invention, the accuracy of the instant at which the brake is released can be improved, which again has a positive effect on the ride comfort of the elevator car. Arranging the sensors to monitor the brake arms, and wiring the brake magnets, is possible without great capital outlay. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0006]    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:  
         [0007]    [0007]FIG. 1 is a perspective view a drive machine with a brake device in accordance with the present invention; and  
         [0008]    [0008]FIG. 2 is an exploded perspective view of the brake device shown in FIG. 1. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0009]    [0009]FIG. 1 shows a gearless drive machine  1  with a motor  2  that has of a stator (not shown) and a rotor (not shown), and drives a traction sheave  3 . Guided over the traction sheave  3  and a return pulley  4  are ropes (not shown) that support and drive an elevator car (not shown) and a counterweight (not shown). The traction sheave  3  is held on a motor shaft  2 . 1  that at one end is supported in a bearing endplate (not shown) and at the other end in a bearing pedestal  5 . The motor  2 , the endplate, the bearing pedestal  5 , and the return pulley  4  are supported by a machine support structure  6 .  
         [0010]    The drive machine  1  further includes a brake device  7  with a first brake arm  8  and a second brake arm  9 , on each of which is arranged a brake shoe which acts on a brake drum (not shown). The brake drum takes the form of, for example, a collar of the traction sheave  3 . The brake arms  8  and  9  are held below in pivoting manner on the bearing pedestal  5 , and above they are guided on a rod  10 . The rod  10 , which serves as a guide element, is arranged centrally on a support  11  fastened to the bearing pedestal  5 . To actuate the brake shoes, a compression spring  12  and  13  is provided on each brake arm  8  and  9 . To release the brake shoes, each brake arm  8  and  9  is provided with a magnet which acts in opposition to the compression spring. The magnets are arranged on a frame  14  that is fastened to the bearing pedestal  5 .  
         [0011]    A guard  15  covers the ropes between the traction sheave  3  and the return pulley  4 . A further guard (not shown) behind the drive machine  1  covers the ropes between the traction sheave  3  and the machine support structure  6 . To cool the drive unit  1 , a ventilating fan  16  is provided. A terminal box  17  serves as interface for power supply cables and as interface for control wiring.  
         [0012]    For emergency operation of the elevator a removable hand drive  18  is provided, which can be connected to the motor shaft  2 . 1  without tools. A cover plate  19  of the bearing pedestal  5  has an opening  20  through which the hand drive  18  can be connected to the motor drive  2 . 1 . The hand drive  18  can be driven by means of a removable handwheel  18 . 1 . In an emergency, the elevator car is moved manually, in either an upward or downward direction depending on the load, to the next stop and the passengers evacuated. By actuating the handwheel  18 . 1 , and simultaneously releasing the brake shoes by means of a removable brake release lever  21 , the motor shaft  2 . 1  is moved manually, thereby lowering or raising the elevator car. The brake release lever  21  has a yoke  22  with a first claw  23  and a handle  24  with a second claw  25 , the yoke being fastened by a swiveling joint  26  to the handle  24 . To release the brake shoes, or specifically the brake arms  8  and  9 , the brake release lever  21  is placed on the rod  10  and the handle  24  moved forward, as a result of which a force opposed to the spring force of the compression springs  12  and  13  acts by means of the claws  23  and  25  on the brake arms  8  and  9  and releases the brake shoes.  
         [0013]    [0013]FIG. 2 shows the construction of the brake device  7 . The brake arms  8  and  9  are arranged at one end to pivot on lever axles  49  and  50 , the lever axles being fastened to the bearing pedestal  5 . Arranged on each brake arm  8  and  9  to pivot on a shoe axle  53  and  54  is a brake shoe  51  and  52  which acts on the brake drum. Each brake arm  8  and  9  is guided at its other end by means of the rod  10  which is fastened to the holder  11  of the bearing pedestal  5 . The compression springs  12  and  13 , which act in the direction of the axis of the rod  10 , press the rod ends of the arms in the direction of the holder  11 , causing the brake shoes  51  and  52  to brake the brake drum and/or hold it fast. At the guided end, each brake arm  8  and  9  has a wider part  55  and  56  which serves as a bearing surface for a disk armature  57  and  58 . The disk armature  57  and  58  is pulled by the magnetic force of an electromagnet  59  and  60  against the spring force of the compression spring  12  and  13 , causing the brake shoe  51  and  52  to be raised from the brake drum, and the brake to be released. The electromagnet  59  and  60  is arranged on a magnet carrier  61  and  62 . Together with stabilizers  63  and  64 , the magnet carriers  61  and  62  form the frame  14 , the magnet carriers  61  and  62  being immovably fastened on their underside to the bearing pedestal  5 . The rigid frame  14  absorbs the forces which arise when the brake is released. Arranged on the inner side of each magnet carrier  61  and  62  with fastening angles  66  is a microswitch  65 . A plunger  67  of the microswitch  65  is actuated by a cam  68  arranged on the disk armature  57 . The switching status of the microswitch  65  indicates to the control of the elevator whether the brake is activated or released. Instead of the microswitch  65 , other sensors, for example proximity switches, can be used. The inner side of the magnet carrier  61  and  62  is covered by means of a cover  70  fastened to the magnet carrier  61  and  62  with a fastening plate  69 , there being provided on the cover  70 , which serves as a guard, recesses  71  for the plunger  67  of the microswitch  65  and for electric wires.  
         [0014]    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.