Abstract:
A belt for suspending and/or driving an elevator car of an elevator system includes a plurality of tension members arranged in a lengthwise direction and a jacket substantially retaining the plurality of tension members. The jacket includes a traction portion, a back portion, and an inner portion between the traction portion and the back portion. The traction portion is formed from a first material and the inner portion is formed from a second material having an increased fire resistance compared to the first material. A method of forming an elevator system belt includes arranging a plurality of tension members in a lengthwise direction and securing the plurality of tension members in a jacket by at least partially enclosing the plurality of tension members in the jacket. The jacket includes a traction portion, a back portion, and an inner portion having a greater fire resistance than the traction portion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 62/158,059 filed May 7, 2015, the contents of which are incorporated by reference herein in their entirety. 
     
    
     BACKGROUND 
       [0002]    The subject matter disclosed herein relates to elevator systems. More specifically, the subject disclosure relates to tension members for elevator suspension and/or driving. 
         [0003]    Elevator systems utilize a lifting means, such as ropes or belts operably connected to an elevator car, and routed over one or more sheaves, also known as pulleys, to propel the elevator along a hoistway. Lifting belts in particular typically include a plurality of wires at least partially within a jacket material. The plurality of wires are often arranged into one or more strands and the strands are then arranged into one or more cords. 
         [0004]    Lifting belts may be required to meet certain established standards to be certified for fire resistance, and/or may require the installation of fire mitigation systems. Thus, the jacket material is often formed of a material with increased fire resistant properties at the outer surface of the belt. Such materials, however, can have non-optimal wear durability and other mechanical performance characteristics. 
       BRIEF SUMMARY 
       [0005]    In one embodiment, a belt for suspending and/or driving an elevator car of an elevator system includes a plurality of tension members arranged in a lengthwise direction and a jacket substantially retaining the plurality of tension members. The jacket includes a traction portion, a back portion, and an inner portion between the traction portion and the back portion. The traction portion is formed from a first material and the inner portion is formed from a second material having an increased fire resistance compared to the first material. 
         [0006]    Additionally or alternatively, in this or other embodiments one or more intermediate layers are located between the traction portion and the inner portion, and/or between the inner portion and the back portion. 
         [0007]    Additionally or alternatively, in this or other embodiments the one or more intermediate layers are formed from a fiberglass fabric, another fire resistant fabric, or a wire metal mesh. 
         [0008]    Additionally or alternatively, in this or other embodiments the back portion has increased fire resistance relative to the traction portion. 
         [0009]    Additionally or alternatively, in this or other embodiments the traction portion and the back portion are formed from the same material. 
         [0010]    Additionally or alternatively, in this or other embodiments an edge treatment is located at one or more lateral edges of the belt to increase fire resistance of the lateral edges. 
         [0011]    Additionally or alternatively, in this or other embodiments the edge treatment includes a layer of material located at one or more lateral edges of the belt having increased fire resistance relative to the traction portion. 
         [0012]    Additionally or alternatively, in this or other embodiments the layer of material is formed from the second material. 
         [0013]    Additionally or alternatively, in this or other embodiments the edge treatment extends in board partially along the traction portion and/or the back portion. 
         [0014]    Additionally or alternatively, in this or other embodiments the edge treatment includes an at least partially exposed tension member. 
         [0015]    Additionally or alternatively, in this or other embodiments the tension member is one of a cord formed from a plurality of metal wires, or metallic strips located at the edge portion 
         [0016]    Additionally or alternatively, in this or other embodiments the edge treatment has a C-shaped cross-section and mechanically interlocks with the jacket. 
         [0017]    Additionally or alternatively, in this or other embodiments the edge treatment is preformed and secured to the jacket during formation of the jacket. 
         [0018]    In another embodiment, an elevator system includes an elevator car movable along a hoistway, a machine located in the hoistway to drive rotation of a traction sheave, and a belt operably connected to the elevator car and interactive with the traction sheave such that rotation of the traction sheave drives movement of the elevator car along the hoistway. The belt includes a plurality of tension members arranged in a lengthwise direction and a jacket substantially retaining the plurality of tension members. The jacket defines a traction portion interactive with the traction sheave, a back portion, and an inner portion between the traction portion and the back portion. The traction portion is formed from a first material and the inner portion is formed from a second material having an increased fire resistance compared to the first material. 
         [0019]    Additionally or alternatively, in this or other embodiments one or more intermediate layers are located between the traction portion and the inner portion, and/or between the inner portion and the back portion. 
         [0020]    Additionally or alternatively, in this or other embodiments the one or more intermediate layers are formed from a fiberglass fabric, another fire resistant fabric, or a wire metal mesh. 
         [0021]    Additionally or alternatively, in this or other embodiments the back portion has increased fire resistance relative to the traction portion. 
         [0022]    Additionally or alternatively, in this or other embodiments the back portion and the traction portion are formed from the same material. 
         [0023]    Additionally or alternatively, in this or other embodiments an edge treatment is positioned at one or more lateral edges of the belt to increase fire resistance of the lateral edges. 
         [0024]    Additionally or alternatively, in this or other embodiments the edge treatment comprises a layer of material having increased fire resistance relative to the traction and/or back portions. 
         [0025]    Additionally or alternatively, in this or other embodiments the layer of material is formed from the second material. 
         [0026]    Additionally or alternatively, in this or other embodiments the edge treatment extends partially along the traction portion. 
         [0027]    Additionally or alternatively, in this or other embodiments the edge treatment includes an at least partially exposed tension member. 
         [0028]    In yet another embodiment, a method of forming an elevator system belt includes arranging a plurality of tension members in a lengthwise direction and securing the plurality of tension members in a jacket by at least partially enclosing the plurality of tension members in the jacket. The jacket includes a traction portion, a back portion, and an inner portion having a greater fire resistance than the traction portion. 
         [0029]    Additionally or alternatively, in this or other embodiments the jacket is trimmed to expose the inner portion at a lateral edge of the jacket thus forming an edge treatment having an increased fire resistance. 
         [0030]    Additionally or alternatively, in this or other embodiments one or more fire retardant edge portions are formed, and the one or more edge portions are secured to one or more lateral edges of the jacket. 
         [0031]    Additionally or alternatively, in this or other embodiments the one or more edge portions are preformed, and the one or more edge portions are guided into a forming tool together with the plurality of tension members. The plurality of tension members are at least partially enclosed in the jacket at the forming tool, and the one or more preformed edge portions are secured to the jacket at the forming tool. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    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: 
           [0033]      FIG. 1A  is a schematic view of an exemplary embodiment of a traction elevator system; 
           [0034]      FIG. 1B  is a schematic view of another exemplary embodiment of a traction elevator system; 
           [0035]      FIG. 1C  is a schematic view of yet another embodiment of a traction elevator system; 
           [0036]      FIG. 2  is cross-sectional view of an embodiment of a belt for a traction elevator system; 
           [0037]      FIG. 3  is a cross-sectional view of another embodiment of a belt for a traction elevator system; 
           [0038]      FIG. 4  is an illustration of a trimming process for an exemplary traction elevator belt; 
           [0039]      FIG. 5  is a cross-sectional view of still another embodiment of a traction elevator belt. 
           [0040]      FIG. 6  is a cross-sectional view of another embodiment of a traction elevator belt; 
           [0041]      FIG. 7  is a cross-sectional view of yet another embodiment of a traction elevator belt; and 
           [0042]      FIG. 8  is a cross-sectional view of still another embodiment of a traction elevator belt. 
       
    
    
       [0043]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION 
       [0044]    Shown in  FIGS. 1A, 1B and 1C  are schematics of exemplary traction elevator systems  10 . Features of the elevator system  10  that are not required for an understanding of the present invention (such as the guide rails, safeties, etc.) are not discussed herein. The elevator system  10  includes an elevator car  12  operatively suspended or supported in a hoistway  14  with one or more belts  16 . The one or more belts  16  interact with one or more sheaves  18  to be routed around various components of the elevator system  10 . The one or more belts  16  could also be connected to a counterweight  22 , which is used to help balance the elevator system  10  and reduce the difference in belt tension on both sides of the traction sheave during operation. 
         [0045]    The sheaves  18  each have a diameter  20 , which may be the same or different than the diameters of the other sheaves  18  in the elevator system  10 . At least one of the sheaves could be a drive sheave  26 . The drive sheave  26  is driven by a machine  24 . Movement of the drive sheave  26  by the machine  24  drives, moves and/or propels (through traction) the one or more belts  16  that are routed around the drive sheave  26 . 
         [0046]    At least one of the sheaves  18  could be a diverter, deflector or idler sheave  18 . Diverter, deflector or idler sheaves  18  are not driven by the machine  24 , but help guide the one or more belts  16  around the various components of the elevator system  10 . 
         [0047]    In some embodiments, the elevator system  10  could use two or more belts  16  for suspending and/or driving the elevator car  12 . In addition, the elevator system  10  could have various configurations such that either both sides of the one or more belts  16  engage the one or more sheaves  18  (such as shown in the exemplary elevator systems in  FIG. 1A, 1B or 1C ) or only one side of the one or more belts  16  engages the one or more sheaves  18 . 
         [0048]      FIG. 1A  provides a 1:1 roping arrangement in which the one or more belts  16  terminate at the car  12  and counterweight  22 .  FIGS. 1B and 1C  provide different roping arrangements. Specifically,  FIGS. 1B and 1C  show that the car  12  and/or the counterweight  22  can have one or more sheaves  18  thereon engaging the one or more belts  16  and the one or more belts  16  can terminate elsewhere, typically at a structure within the hoistway  14  (such as for a machineroomless elevator system) or within the machine room (for elevator systems utilizing a machine room. The number of sheaves  18  used in the arrangement determines the specific roping ratio (e.g. the 2:1 roping ratio shown in  FIGS. 1B and 1C  or a different ratio). One skilled in the art will readily appreciate that the configurations of the present disclosure could be used on elevator systems other than the exemplary types shown in  FIGS. 1A, 1B and 1C . 
         [0049]    Referring to  FIG. 2 , a cross-sectional view of an exemplary belt  16  is shown. The belt  16  is constructed of one or more cords  28  in a jacket  30 . The cords  28  of the belt  16  may all be identical, or some or all of the cords  28  used in the belt  16  could be different than the other cords  28 . For example, one or more of the cords  28  could have a different construction, formed from different materials, or size than the other cords  28 . As seen in  FIG. 2 , the belt  16  has an aspect ratio greater than one (i.e. belt width is greater than belt thickness). Each cord  28  comprises a plurality of wires  32 , which in some embodiments are formed into strands  34 , which are then formed into the cord  28 . 
         [0050]    The belt  16  is constructed to have sufficient flexibility when passing over the one or more sheaves  18  to provide low bending stresses, meet belt life requirements and have smooth operation, while being sufficiently strong to be capable of meeting strength requirements for suspending and/or driving the elevator car  12 . 
         [0051]    The jacket  30  includes a traction portion  36  interactive with and contacting the drive sheave  26  and a back portion  38  opposite the traction portion  36 . Further, a width of the belt  16  is defined by edge portions  40 . An inner portion  42  of the belt  16  may be located between the traction portion  36  and the back portion  38 . The traction portion  36  and back portion  38  each have thicknesses extending across a thickness of the belt  16  so that the desired materials of the traction portion  36  and back portion  38  are present at these locations over a service life of the belt  16 . 
         [0052]    The jacket  30 , for example, inner portion  42 , can substantially retain the cords  28  therein. The phrase substantially retain means that the jacket  30  has sufficient engagement with the cords  28  such that the cords  28  do not pull out of, detach from, and/or cut through the jacket  30  during the application on the belt  16  of a load that can be encountered during use in an elevator system  10  with, potentially, an additional factor of safety. In other words, the cords  28  remain at their original positions relative to the jacket  30  during use in an elevator system  10 . The jacket  30  could completely envelop the cords  28  (such as shown in  FIG. 2 ), substantially envelop the cords  28 , or at least partially envelop the cords  28 . 
         [0053]    The portions  36 ,  38 ,  40  and  42  of the jacket  30  may be formed from a number of different materials. For example, in one embodiment, the traction portion  36  is formed from a first material, for example a thermoplastic polyurethane (TPU) material. The first material has desired mechanical properties for desired traction, low noise and wear properties. Further, in embodiments of elevator systems  10  where the back surface  38  back portion  38  contacts sheaves  18 , it may be desired to form back portion  38  from the first material to provide the same mechanical properties at the back portion  38  as at the traction portion  36 . 
         [0054]    As stated above, the inner portion  42  of the belt  16  is located between the traction portion  36  and the back portion  38 . The inner portion  42  is configured to have a degree of fire resistance greater than the traction portion  36 . The inner portion  42  may be formed from a second material, such as a material including a percentage of melamine cyanurate (MC) to increase its fire resistance relative to the traction portion  36  material. In some embodiments, the inner portion  42  is approximately  60 % to 90% of a thickness  44  of the belt  16 . The material layer thickness of the traction portion  36  and/or the back portion  38  may vary in thickness. Some embodiments may include an intermediate layer  46 , for example, a fiberglass fabric or wire metal mesh between the traction portion  36  and the inner portion  42  or as a replacement for the inner portion  42 . The intermediate layer  46  may be either embedded in the belt  16  or located at the back portion  38 . The inner portion  42  and/or the intermediate layer  46  are positioned and configured to prevent burn through or melt through of the belt  16  thus leading to improved fire resistance of belt  16 , while the traditional first material is utilized at the traction portion  36  to provide the expected traction, noise level, wear rate and other properties of belt  16  operation. 
         [0055]    Referring to  FIG. 3 , in an alternate embodiment the traction portion  36  is formed from the first material, and the remaining thickness of the belt  16 , extending to the back portion  38 , is formed from the second material, the inner portion  42  extending from the traction portion  36  and extending to an defining the back portion  38 . 
         [0056]    Referring again to  FIG. 2 , embodiments may include one or more edge treatments to reduce the effect of flame spread and wraparound from the traction portion  36  to the back portion  38 , or vice versa. In the embodiment of  FIG. 2 , the belt edge portion  40  are formed from the fire resistant second material, but in other embodiments may be formed from a different fire resistant material. The edge portion  40  extends inboard partially across the traction portion  36  and/or the back portion  38 . It is desired to minimize the wraparound flame spread so that the fire resistance of the edge portion  40  is maintained while minimizing the impact on performance of the traction portion  36 . In some embodiments, the edge portion  40  extends laterally inboard about 3 mm, but can vary according to desired performance. 
         [0057]    The edge portions  40  may be formed in any one of several ways. One method of forming the edge portion  40  is illustrated in  FIG. 4 . In the embodiment of  FIG. 4 , the edge portion  40  is formed oversized in both thickness  50  and width  52 , and may be formed via, for example, co-extrusion with the traction portion  36 , the back portion  38  and the inner portion  42 , or may be formed via a secondary extrusion or other process. After forming, the edge portion  40  is trimmed along trim lines  54  to a selected shape to expose the fire retardant material of the edge portion  40 . The trimming operation allows for a well-defined transition area  56  between the first material of the traction portion  36  and the second material of the edge portion  40 , and ensures a selected thickness of the first material at the transition area  56 . 
         [0058]    Referring now to  FIG. 5 , in another embodiment the edge portion  40  is formed by trimming or by extruding or otherwise forming the belt  16  so that at least a portion of an end cord  28  is exposed. The metal material of the cord  28  acts as a fire resistant material to protect the belt  16 . In some embodiments, about 25% to 50% of a lateral width of the cord  28  is exposed, so the cord  28  provides fire resistance while still being securely retained in the jacket  30 . The cord cross-section for these end cords could deviate from circular and, for example, could be constructed of metallic strips or other fire resistant materials. 
         [0059]    In other embodiments of belt  16  shown in  FIGS. 6 and 7 , the edge portion  40  is pre-formed separately rather than being formed as the material flowing through the extruder screw in an extrusion process. The pre-formed edge portion  40  is then fed into the extrusion die along with the cords  18 . The preformed edge portion  40  then joined to the other jacket portions  36 ,  38 ,  42  of the belt  16  via a combination of adhesion and mechanical interlocking. In the embodiments of  FIGS. 6 and 7 , the edge portion  40  is formed as a “C” geometry shape that achieves mechanical interlocking, but those skilled in the art will readily appreciate that edge portions  40  may be formed to other geometric shapes. In some embodiments, such as in  FIG. 7 , one or more cords  18  may be positioned within an envelope of the edge portion  40 , particularly in those embodiments where edge portion  40  material has desired wear and noise performance properties. With this approach, materials with greater fire resistance can be used without the need to be processable in the extruder screw and/or at the same time as the remaining jacket material. These preformed edge portions  40  can be made by separate extrusion, machining, lamination and other continuous processes. 
         [0060]    In another embodiment, illustrated in  FIG. 8 , the edge portion  40  is located at an edge distance  60  from the end cord  28  that is at least one half of a cord diameter  58  with a maximum preferred edge distance  60  of about two cord diameters  58  so that stresses imparted to the jacket material by the cord  18  as it presses the jacket  30  against the sheave is substantially reduced. 
         [0061]    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.