Abstract:
A braking system for an elevator system includes two or more braking surfaces located at an elevator car and frictionally engageable with a rail of an elevator system. One or more actuators are located at the elevator car and are operably connected to at least one braking surface of the two or more braking surfaces. The one or more actuators are configured to urge engagement and/or disengagement of the at least one braking surface with the rail to stop and/or hold the elevator car during operation of the elevator system. One or more braking guides are located at the elevator car to maintain a selected distance between the two or more braking surfaces and the rail.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to elevator systems. More specifically, the subject disclosure relates to braking systems for elevators. 
         [0002]    Traction elevator systems are driven by a motor having a traction sheave, referred to as a machine, which drives a lifting means, typically ropes or belts, attached to an elevator car. The speed and motion of the elevator car are controlled by a variety of devices scattered throughout the elevator system which are installed and adjusted individually. For example, a brake at the machine is used to hold the elevator car during normal operation and as a first response to stop and hold the elevator car during emergency operation. In addition, safety brakes are mounted on the elevator car are utilized as a redundant braking device to stop the car in the hoistway in the event of an emergency. Installation and setup of all of these separate devices is costly and time consuming. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    According to one aspect of the invention, a braking system for an elevator system includes two or more braking surfaces located at an elevator car and frictionally engageable with a rail of an elevator system. One or more actuators are located at the elevator car and are operably connected to at least one braking surface of the two or more braking surfaces. The one or more actuators are configured to urge engagement and/or disengagement of the at least one braking surface with the rail to stop and/or hold the elevator car during operation of the elevator system. One or more braking guides are located at the elevator car to maintain a selected distance between the two or more braking surfaces and the rail. 
         [0004]    Additionally or alternatively, the invention may include one or more of the following features, either individually or in various combinations: the one or more actuators including one or more electrical coils magnetically interactive with the at least one braking surfaces; the one or more electrical coils configured to urge the at least one braking surface away from the rail when energized; at least one biasing member to bias the at least one braking surface toward the rail; the at least one biasing member comprising a stack of disc springs; at least one support to connect the braking system to the elevator car; the braking system being slidably connected to the at least one support; and the at least one support at least partially formed of a compliant material. 
         [0005]    According to another aspect of the invention, an elevator system includes one or more rails fixed in a hoistway and an elevator car configured to move through the hoistway along the one or more rails. One or more braking systems are secured to the elevator car and include two or more braking surfaces frictionally engageable with the one or more rails. One or more actuators are operably connected to at least one braking surface of the two or more braking surfaces. The one or more actuators are configured to urge engagement and/or disengagement of the at least one braking surface with the rail to stop and/or hold the elevator car during operation of the elevator system. One or more braking guides are located at the elevator car to maintain a selected distance between the two or more braking surfaces and the rail. 
         [0006]    Alternatively in this or other aspects of the invention, the one or more braking systems is four braking systems. 
         [0007]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0009]      FIG. 1  is a schematic of an embodiment of an elevator system; 
           [0010]      FIG. 2  is a perspective view of an embodiment of a braking system for an elevator; 
           [0011]      FIG. 3  is a cross-sectional view of an embodiment of a braking system for an elevator; 
           [0012]      FIG. 4  is another cross-sectional view of an embodiment of a braking system for an elevator; 
           [0013]      FIG. 5  is a perspective view of another embodiment of a braking system for an elevator; 
           [0014]      FIG. 6  is a perspective view of yet another embodiment of a braking system for an elevator; 
           [0015]      FIG. 7  is a perspective view of still another embodiment of a braking system for an elevator; 
           [0016]      FIG. 8   a  is a perspective view of another embodiment of a braking system for an elevator; 
           [0017]      FIG. 8   b  is a perspective view of yet another embodiment of a braking system for an elevator; and 
           [0018]      FIG. 9  is a cross-sectional view of another embodiment of a braking system for an elevator. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Shown in  FIG. 1  is an embodiment of an elevator system  10 . The elevator system  10  includes a motor  11   a  having a traction sheave  11   b  for driving the elevator system, known as a machine  12 . The machine  12  drives a lifting means, for example, one or more belts or ropes, hereinafter referred to as “ropes”  14  over one or more pulleys to urge motion of an elevator car  16  up and/or down in a hoistway  18 . One or more rails  20 , typically at least two rails  20 , are located in the hoistway  18  and the elevator car  16  is positioned in the hoistway  18  such that the rails  20  guide the motion of the elevator car  16 . A braking system, generally shown at  22 , is secured to the elevator car  16 . The braking system  22  interacts with the rails  20  to hold the elevator car  16  during normal operation of the elevator  10 , for example, stopping at a floor to load and/or unload passengers. Further, some embodiments of the braking system  22  include the function of a traditional emergency brake, or safety, to slow and/or stop movement of the elevator car  16  in the event of an emergency, for example, the elevator car  16  exceeding a predetermined speed,. 
         [0020]    Referring to  FIG. 2 , shown is an embodiment of a braking system  22 . The braking system  22  is secured to the elevator car  16  via, for example one or more supports  24  with the various components of the braking system  22  secured thereto. In the embodiment of  FIG. 2 , each support  24  is u-shaped, with a support  24  located at each end of the braking system  22 . In some embodiments, four braking systems  22 , are fixed to the elevator car  16 , with two braking systems  22  at each of the two rails  20 . The braking system  22  includes a backing block  26  located at each side of the rail  20 . The backing blocks  26  are secured to a brake bracket  28 . A braking plate  30  with a brake pad  32  affixed thereto is located between each backing block  26  and the rail  20 . The braking plate  30  is articulable toward the rail  20  such that the brake pads  32  engage the rail  20  to slow, stop or hold the elevator car  16  via friction. 
         [0021]    Referring to  FIG. 3 , the braking plate  30  and brake pads  32  are biased toward the rail  20  by a plurality of springs, for example one or more disc spring stacks  34 . Each spring stack  34  is located in a spring pocket  36  in the backing block  26 , and in some embodiments are arranged around a spring pin  38  which acts as a spring guide for the spring stack  34 . Alternatively, a pocket wall  40  may act as the spring guide. One or more electrical coils  42  are located in the backing block  26 . When energized, the electrical coils  42  generate a magnetic field to overcome the bias of the spring stacks  34  to draw the brake pads  32  away from the rail  20  to allow movement of the elevator car  16  along the rail  20 . When it is desired to slow, stop or hold the elevator car  16 , the electrical coils  42  are deenergized, thereby allowing the spring stacks  34  to urge the brake pads  32  into contact with the rail  20 . The necessary braking force to slow, stop or hold the elevator car  12  is provided by spring force of the spring stacks  34  forcing the brake pads  32  into contact with the rail  20 , and by frictional forces of the brake pad  32  on the rail  20 . 
         [0022]    Referring to  FIG. 4 , the braking system  22  is secured to the supports  24  with side-to-side “play” to allow side-to-side movement of the braking system  22  relative to the supports  24 . This allows the braking system  22  to follow any waves or other such changes in rail position along the length of the rail  20 . In some embodiments, the play is achieved by mounting the braking system  22  to the supports  24  via one or more mounting pins  44  extending from the backing block  26  through the support  24 . The mounting pins  44  may be slidably located at the supports  24  to allow the side to side movement of the braking system  22 . It is to be appreciated, however, that the mounting scheme of  FIG. 4  is merely exemplary. 
         [0023]      FIGS. 5-8  illustrate exemplary alternative mounting schemes for the braking system  22 . In  FIG. 5 , the brake bracket  28  includes a bracket tab  46 , with the mounting pin  44  extending through the bracket tab  46  into the support  24 .  FIG. 6  illustrates an embodiment where the supports  24  are connected to the braking system  22  at a flange  50  of the brake bracket  28 .  FIG. 7  illustrates an embodiment where a single support  24  extending the length of the braking system  22  is utilized. In the embodiment of  FIG. 8 , the supports  24  are formed from a compliant material such as an elastomer. The compliant material allows the side to side movement of the braking system  22 . 
         [0024]    Referring again to  FIG. 2 , the braking system  22  includes one or more brake guides  48 . The brake guides  48  are formed from a low friction material and are located at each side of the rail  20  and extend toward the rail  20  such that when the brake pads  32  are in a retracted position, the brake guides  48  contact the rail  20  before the brake pads  32  and are utilized to maintain a selected distance between the brake pads  32  and the rail  20  when the braking system  22  is not activated. The brake guides  48  are fixed relative to the braking system  22  to urge the side to side movement of the braking system  22  when variation in the rail  20  position is encountered. When activated, the braking plate  30  and brake pads  32  move relative to the backing blocks  26  and guides  48  and move towards the rail  20 . As shown in  FIG. 2 , the brake guides  48  may be fixed to the backing blocks  26 , or alternatively may be integral to the backing blocks  26 . Use of the brake guides  48  allows the brake pads  32  to be positioned closer to the rail  20  when the brake pads  32  are in a retracted position. Maintaining a selected distance between the braking surfaces and the rail  20  permits the braking system to reduce the required travel of the braking plate  30  to engage the rail  20 . Reducing the clearance between the rail  20  and the brake pads  32  reduces the force necessary to retract the brake pads  32  and thereby the size of the actuator, such as the coils  42 , required for this function. 
         [0025]    Alternatively the guides  48  could be rollers on one or both sides of the rail  20 . If the guides  48  were only located on one side of the rail  20 , the braking system  22  would be biased in such a way—by a spring or other such device—that the guides  48  would normally be in contact with the rail  20  when the braking system  22  is not activated. 
         [0026]    Further, as shown in  FIG. 8 , the brake guides  48  may alternatively extend through the braking plate  30  through a guide opening in the braking plate  30 , with the braking plate  30  moving past the brake guides  48  during actuation of the brake assembly  22 . 
         [0027]    Referring now to  FIG. 9 , in addition to the dual-sided braking systems  22  described above, the braking system  22  may be single-sided, with a fixed brake pad  32  at a first side of the rail  20  and a movable braking plate  30  and brake pad  32  located at a second side of the rail  20 . When the electrical coils  42  are deenergized, the movable braking plate  30  and brake pad  32  is urged into contact with the rail  20  and further draws the fixed brake pad  32  into contact with the rail  20 . 
         [0028]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.