Patent Publication Number: US-8113318-B2

Title: Elevator machine with integrated brake surface

Description:
FIELD OF THE INVENTION 
     This invention generally relates to elevator systems and, more particularly, to elevator machine brakes. 
     DESCRIPTION OF THE RELATED ART 
     Many elevator systems include some form of load bearing member, such as a rope or a belt for supporting and moving the cab through a hoistway as desired. The load bearing member typically couples a counterweight to the cab. Typical geared or gearless arrangements include a motorized elevator machine that moves the load bearing member to move the cab through the hoistway. 
     One typical motorized elevator machine includes a machine shaft supported by a pair of bearing stands. Each bearing stand includes a bearing that rotationally supports the machine shaft. A motor rotationally drives the machine shaft. A sheave on the machine shaft between the bearing stands and rotates with the machine shaft. The ropes or belts are typically tracked through the sheave such that the motor may rotate the sheave in one direction to lower the cab and rotate the sheave in the opposite direction to raise the cab. 
     In such arrangements, the machine shaft typically extends beyond one of the bearing stands into a brake. A typical brake includes a fixed brake plate, an electromagnet, springs, a moveable brake armature, and a disk that rotates with the machine shaft. The disk extends between the fixed brake plate and the brake armature. The brake armature selectively clamps the disk between the brake armature and the fixed brake plate to hold the machine shaft and sheave when the cab is at a selected landing. 
     In one particular arrangement, the electromagnet, springs, and brake armature are contained in a brake housing that is secured to the fixed brake plate. This assembly is then secured to the bearing stand of the elevator machine Alternatively, the fixed brake plate is secured to the bearing stand using bolts and the electromagnet, springs, and brake armature are contained in a brake housing that is secured to the bearing stand with the disk between the brake armature and the fixed brake plate. 
     In another arrangement shown in EP 0 736 477 B1, an elevator brake includes a base and an electromagnet that are built into a housing outer wall section of an elevator machine or gearbox. Several fixed brake plates are supported on dowel pins that extend from the machine housing. An armature selectively clamps several disks that extend between the fixed brake plates together to resist rotation of a shaft. 
     Although such arrangements are effective for braking, those skilled in the art are always striving to improve performance, economies or both. There is a desire to simplify and reduce the manufacturing expense of elevator machine brakes. 
     SUMMARY OF THE INVENTION 
     One example elevator machine includes a machine shaft and a sheave that rotates with the machine shaft. A motor selectively rotates the machine shaft. A brake having at least one brake armature selectively moves a brake rotor coupled for rotation with the shaft between a braking position and a released position. The brake rotor selectively contacts a braking surface formed directly on a housing to resist rotation of the machine shaft in the braking position. 
     In one disclosed embodiment, the housing is a bearing stand having a bearing that rotationally supports the machine shaft and the bearing stand is a single, monolithic structure that provides the braking surface and supports the shaft. 
     In another disclosed embodiment, the housing is a gearbox housing. In another disclosed embodiment, the housing is a motor housing. 
     The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates selected portions of an example elevator machine that includes a housing having a braking surface. 
         FIG. 2  illustrates selected portions of the brake shown in  FIG. 1 . 
         FIG. 3  illustrates a second example elevator machine that includes a housing having a braking surface. 
         FIG. 4  illustrates a third example elevator machine that includes a housing having a braking surface. 
         FIG. 5  illustrates a fourth example elevator machine that includes a housing having a braking surface. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates selected portions of an example elevator machine  10 . In this example, the elevator machine  10  includes a motor  12  that rotationally drives a machine shaft  14  about an axis  16 . In the arrangement shown, the machine  10  includes a housing  18  that supports the machine shaft  14 . The housing  18  in this example, includes a first bearing stand  20  and a second bearing stand  22 . Each bearing stand  20  and  22  includes a bearing  24  that rotationally supports the machine shaft  14  and generally prevents movement of the machine shaft in a direction perpendicular to the axis  16 . The bearing stands  20  and  22  also provide structural integrity to the machine  10  assembly to transmit a portion of the load on the machine  10  to other elevator elements, such as a bedplate or brackets, which eventually distribute the load to the building structure. A sheave  26  on the machine shaft  14  between the bearing stands  20  and  22  rotates with the machine shaft  14  to raise or lower a cab in a known manner. 
     In this example, the machine shaft  14  extends through the first bearing stand  20  into an elevator brake assembly  30 . The brake assembly  30  includes a rotor  28  that is coupled for rotation in a known manner with the machine shaft  14 , such as with a splined connection. The brake assembly  30  selectively applies a braking force on the machine shaft  14  to prevent rotation of the machine shaft  14 . A controller  32  selectively operates the motor  12  and the elevator brake assembly  30  to control movement of the cab. 
       FIG. 2  illustrates a cross-section of the elevator brake assembly  30 . In this example, the elevator machine brake  30  includes an armature  36  for clamping the rotor  28  to apply a braking force on the machine shaft  14 . The armature  36  is shown in a split configuration in this example, however, a variety of known configurations other than a split armature can be used. Bias members  38  bias the armature  36  in a brake-applying direction toward the rotor  28 . 
     In this example, the first bearing stand  20  includes a braking surface  44 . The armature  36  clamps the rotor  28  against the braking surface  44  to resist rotation of the machine shaft  14 . In the illustrated example, the rotor  28  includes brake linings  40  for wear resistance. One of the brake linings  40  in this example directly contacts the braking surface  44 . Optionally, the brake lining  40  is on the braking surface  44  (shown in phantom in  FIG. 1 ) instead of the rotor  28  to resist wearing the braking surface  40 . 
     In this example, the braking surface  44  of the first bearing stand  20  is a flat surface. The braking surface  44  may be machined to achieve a desired level of flatness to promote uniform braking force distribution when the armature  36  clamps the rotor  28  against the braking surface  44 . In another example, the braking surface  44  is an as-formed surface, such as from a casting process without the aid of machining. As can be appreciated, machining may be necessary to achieve a desired flatness tolerance. Given this description, one of ordinary skill in the art will recognize suitable methods for achieving a particular desired flatness. 
     The controller  32  selectively activates an electromagnet  54  to overcome the bias force provided by the bias members  38 . In this example, when the machine shaft  14  starts rotating, the motion separates the rotor  28  from the braking surface  44  such that the rotor  28  rotates free from contact with the braking surface  44 . Upon deactivation of the electromagnet  54 , the bias members  38  actuate the armature  36  to again clamp the rotor  28  against the braking surface  44  of the first bearing stand  20 . As can be-appreciated from this movement, the rotor  28  slides along the machine shaft  14  such that it is spaced from the braking surface  44  and rotor  28  when in a released position to allow free rotation. 
     In the illustrated example, the armature  36 , bias members  38 , and electromagnet  54  are retained in a housing  56  that is secured to the bearing stand  20  using fasteners  58  in this example. 
     As can be appreciated from  FIGS. 1 and 2 , the first bearing stand  20  is a single, monolithic structure that integrates several different components to achieve several different functions in the elevator machine  10 . The term “monolithic” as used in this description refers to a single homogenous structure rather than an assembly of secured together pieces. In the disclosed example, the first bearing stand  20  is a single formed piece, such as a cast piece, that incorporates the braking surface  44  and supports the bearing  24 . The integration of the braking surface  44  and the bearing  24  into the housing  18  provides the benefit of reducing the number of components in the elevator machine  10  by eliminating the need for a separate, fixed brake plate as typically used in known elevator machine brakes. By eliminating the fixed brake plate, the elevator machine  10  also has a smaller footprint compared to prior elevator machines. 
       FIG. 3  shows a simplified illustration of a modified embodiment. In this example, the braking surface  44  is located on the second bearing stand  22  instead of the first bearing stand  20  as in the example shown in  FIGS. 1 and 2 . The brake assembly  30  is also between the bearing stands  20  and  22  such that the braking surface  44  faces toward the first bearing stand  20 . The braking surface  44  of this example provides similar benefits as the example shown in  FIGS. 1 and 2 . 
       FIG. 4  shows a simplified illustration of another modified embodiment. In this example, the machine  10  is a geared machine that includes a gearbox  80 . The gearbox  80  includes a gear set  82  (shown schematically) that couples the shaft  14  (a motor shaft in this example) with an output shaft  14 ′ on which the sheave  26  is disposed in a known manner. A gearbox housing  84  encloses the gear set  82  to shield it from the environment. In this example, the gearbox housing  84  includes the braking surface  44  for resisting rotation of the output shaft  14 ′ in a similar manner as previously described. Alternatively, the brake assembly  30  is attached to the motor  12  and acts on the shaft  14  (similar to  FIG. 5 ). The braking surface  44  of this example provides similar benefits as the example shown in  FIGS. 1 and 2 . 
       FIG. 5  shows a simplified illustration of another modified embodiment. In this example, the brake assembly  30  is located on the other end of the shaft  14  than in the example illustrated in  FIGS. 1 and 2 . A motor housing  90  that encloses the motor  12  to shield it from the environment includes the braking surface  44  for resisting rotation of the shaft  14  as previously described. The braking surface  44  of this example provides similar benefits as the example shown in  FIGS. 1 and 2 . 
     As can be appreciated from the disclosed examples, the braking surface  44  can be integrated into a variety of different types of housings in a variety of different elevator machine  10  arrangements. Although the disclosed examples show particular housings in particular arrangements, the principles and beneficial features demonstrated by the disclosed examples, alone or in combination, are not limited to the disclosed embodiments. 
     The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.