Abstract:
A belt for suspending and/or driving an elevator car includes a plurality of tension elements extending longitudinally along a length of the belt, and a jacket at least partially encapsulating the plurality of tension elements. The jacket defines a traction surface of the belt configured to be interactive with a drive sheave and a back surface opposite the traction surface. The jacket is formed from a first material. One or more material strips are located at one or more of the traction surface or the back surface to improve one or more operational characteristics of the belt. The one or more material strips formed from a second material different from the first material.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Provisional Application No. 62/293,078 filed Feb. 9, 2016, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    The subject matter disclosed herein relates to belts such as those used in elevator systems for suspension and/or driving of the elevator car and/or counterweight. 
         [0003]    Conventional elevator systems use rope formed from steel wires as a lifting tension load bearing member. Other systems utilize a belt formed from a number of steel cords, formed from steel wires, retained in a polymer jacket formed from, for example, thermoplastic polyurethane. The cords act as the load supporting tension member, while the jacket holds the cords in a stable position relative to each other, and provides a frictional load path to provide traction for driving the belt. 
         [0004]    Elevator belt surfaces need to meet specific performance and life requirements. Two critical requirements are traction within a specified range and wear sufficient to meet life targets, in some instances in the range of 10-20 years. Conventional belts are based on single elastomer jacket materials at the operating traction and non-traction surfaces. 
         [0005]    Complex formulations containing elastomers, polymeric additives, waxes, friction modifiers, carbon black and other additives make up the jacket composition. These single formulations are expected to meet all requirements over a range of varying conditions for the life of the belt. However, variations can and do occur owing to changes in surface composition due to temperature, aging and wear. In addition, uneven pressure and slip across a width of the belt can lead to uneven wear. The high wear typically occurs at locations on the belt where the combination of slip and pressure is the highest. The center of the belt is typically subject to high pressure and low slip, the sections of the belt closest to each edge, lower pressure and higher slip. 
         [0006]    Complete wearing of a section of the belt down to the inner tension members results in end of life. Strategies have been proposed to develop robust and complex formulations to improve jacket performance. Unfortunately this approach is complex and requires requalification of the jacket material. In addition, the goal of meeting multiple requirements over a product lifetime is difficult. 
       SUMMARY 
       [0007]    In one embodiment, a belt for suspending and/or driving an elevator car includes a plurality of tension elements extending longitudinally along a length of the belt, and a jacket at least partially encapsulating the plurality of tension elements. The jacket defines a traction surface of the belt configured to be interactive with a drive sheave and a back surface opposite the traction surface. The jacket is formed from a first material. One or more material strips are located at one or more of the traction surface or the back surface to improve one or more operational characteristics of the belt. The one or more material strips formed from a second material different from the first material. 
         [0008]    Additionally or alternatively, in this or other embodiments the second material is configured to counteract wear of the belt. 
         [0009]    Additionally or alternatively, in this or other embodiments the second material is one of a wear resistant elastomer, a wear resistant fabric or an elastomer having friction properties different from the first material. 
         [0010]    Additionally or alternatively, in this or other embodiments the one or more material strips are applied over the traction surface. 
         [0011]    Additionally or alternatively, in this or other embodiments one or more grooves are formed in the jacket, and the one or more material strips are inserted into the one or more grooves. 
         [0012]    Additionally or alternatively, in this or other embodiments the jacket includes a retaining feature to mechanically connect the one or more material strips to the first jacket material. 
         [0013]    Additionally or alternatively, in this or other embodiments one or more material strips are positioned at the back surface of the belt, opposite the traction surface. 
         [0014]    Additionally or alternatively, in this or other embodiments one or more undercuts are located in the jacket in regions of predicted high levels of wear. 
         [0015]    Additionally or alternatively, in this or other embodiments the one or more material strips are located at one or more belt width ends. 
         [0016]    Additionally or alternatively, in this or other embodiments one or more of the jacket or the material strips are formed from one or more of polyurethane, styrene butadiene rubber, nitrile rubber, neoprene, fluoroelastomer, silicone rubber, room temperature vulcanizate, natural rubber, or EPDM. 
         [0017]    Additionally or alternatively, in this or other embodiments one or more of the jacket or the material strips include one or more additives of small molecule additives such as liquids, oils, paraphinic waxes, ionic liquids, fire retardants, or particulate additives such as inorganics or organics. 
         [0018]    In another embodiment, an elevator system includes a hoistway, and an elevator car positioned in the hoistway and drivable along the hoistway. A drive sheave is positioned in the hoistway and a belt is operably connected to the elevator car and the drive sheave to drive the elevator car along the hoistway. The belt includes a plurality of tension elements extending longitudinally along a length of the belt and a jacket at least partially encapsulating the plurality of tension elements. The jacket defines a traction surface of the belt configured to be interactive with the drive sheave and a back surface opposite the traction surface. The jacket is formed from a first material. One or more material strips are positioned at one or more of the traction surface or the back surface to improve one or more operational characteristics of the belt. The one or more material strips are formed from a second material different from the first material. 
         [0019]    Additionally or alternatively, in this or other embodiments the second material is configured to counteract wear of the belt. 
         [0020]    Additionally or alternatively, in this or other embodiments the second material is one of a wear resistant elastomer, a wear resistant fabric or an elastomer having friction properties different from the first material. 
         [0021]    Additionally or alternatively, in this or other embodiments the one or more material strips are applied over the traction surface. 
         [0022]    Additionally or alternatively, in this or other embodiments one or more grooves are formed in the jacket and the one or more material strips are inserted into the one or more grooves. 
         [0023]    Additionally or alternatively, in this or other embodiments the jacket includes a retaining feature to mechanically connect the one or more material strips to the jacket. 
         [0024]    Additionally or alternatively, in this or other embodiments one or more material strips are positioned at a back surface of the belt, opposite the traction surface. 
         [0025]    Additionally or alternatively, in this or other embodiments one or more undercuts are located in the jacket in regions of predicted wear. 
         [0026]    Additionally or alternatively, in this or other embodiments the one or more material strips are positioned at one or more belt width ends. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The subject matter which is regarded as the present disclosure 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 present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0028]      FIG. 1A  is a schematic of an exemplary elevator system having a 1:1 roping arrangement; 
           [0029]      FIG. 1B  is a schematic of another exemplary elevator system having a different roping arrangement; 
           [0030]      FIG. 1C  is a schematic of another exemplary elevator system having a cantilevered arrangement; 
           [0031]      FIG. 2  is an end view of an embodiment of an elevator belt; 
           [0032]      FIG. 3  is a cross-sectional view of an embodiment of a tension element of an elevator belt; 
           [0033]      FIG. 4  is a cross-sectional view of an embodiment of an elevator belt; 
           [0034]      FIG. 5  is a cross-sectional view of another embodiment of an elevator belt; 
           [0035]      FIG. 6  is a cross-sectional view of yet another embodiment of an elevator belt; 
           [0036]      FIG. 7  is a cross-sectional view of still another embodiment of an elevator belt; and 
           [0037]      FIG. 8  is a cross-sectional view of another embodiment of an elevator belt. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]    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 disclosure (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. 
         [0039]    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 would be a traction sheave  52 . The traction sheave  52  is driven by a machine  50 . Movement of drive sheave by the machine  50  drives, moves and/or propels (through traction) the one or more belts  16  that are routed around the traction sheave  52 . 
         [0040]    At least one of the sheaves  18  could be a diverter, deflector or idler sheave. Diverter, deflector or idler sheaves are not driven by a machine  50 , but help guide the one or more belts  16  around the various components of the elevator system  10 . 
         [0041]    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  FIGS. 1A, 1B or 1C ) or only one side of the one or more belts  16  engages the one or more sheaves  18 . 
         [0042]      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).  FIG. 1C  also provides a so-called rucksack or cantilevered type elevator. The present embodiments could also be used on elevator systems other than the exemplary types shown in  FIGS. 1A, 1B and 1C . 
         [0043]    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). Referring to  FIG. 3 , 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 . 
         [0044]    Referring again to  FIG. 2 , 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 . 
         [0045]    The jacket  30  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 . 
         [0046]    Referring now to  FIG. 4 , shown is an embodiment of a belt  16  having  10  cords  28  arrayed along a belt width  40 . The belt  16  is roughly rectangular in cross-section and in some embodiments a belt width  40  is in the range of 20-50 millimeters and a belt thickness  42  is in the range of 3-8 millimeters. The jacket  30  includes a traction surface  36  interactive with and contacting the drive sheave  26  and a back surface  38  opposite the traction surface  36 . The back surface  38  may be interactive with other sheaves  18 , such as diverter, deflector or idler sheaves  18 . One or more of the sheaves  18  may have a crowned sheave surface to steer or guide the belt  16 . The crowned sheave surface  18 , alone or in combination with other factors, results in uneven pressure on the traction surface  36  and/or the back surface  38  causing uneven slip and/or wear of the belt  16 . Referring again to  FIG. 4 , the belt  16  includes material strips  46  on the traction surface  36  to counteract high wear of select portions of the traction surface  36  due to, for example, uneven pressure on the traction surface  36  during operation of the elevator system  10 . In one embodiment, the material strips are applied over cord  28   b  and cord  28   i , corresponding to anticipated high levels of wear in those areas of belt  16 . The material strips  46  are configured to counteract high levels of wear and may be formed from, for example, a wear resistant elastomer, a wear resistant fabric or an elastomer with higher or lower friction properties to raise or lower the friction and traction of the belt  16 . In particular, a lower friction material is beneficial to help reduce wear of the belt  16 , and may include a damped material to reduce belt  16  noise during operation. Further, in some embodiments, material strips  46  may be utilized not only at the traction surface  36  but at the back surface  38  in addition to or as an alternative to material strips  46  at the traction surface  36 . In some embodiments, the material strips  46  cover 5% to 50% of the traction surface  36 . Application of material strips  46  is not limited to over cord  28   b  and  28   i , but in some embodiments may be applied at other locations of the traction surface  36  and/or the back surface  38 . For example, in some embodiments, a material strip  46  of a low coefficient of friction material may be applied at a center of the traction surface  36  to promote microslip at the belt  16  center, while reducing microslip at outboard regions of the belt  16 . In some embodiments, material strips  46  in different belt  16  locations may be formed from different materials to enhance different properties of the belt  16  operation. 
         [0047]    The jacket  30  and material strips  46  may be formed from of any of but not limited to the following materials: polyurethane, styrene butadiene rubbers, nitrile rubber, neoprene, fluoroelastomer, silicone rubber, room temperature vulcanizates, natural rubber, EPDM. 
         [0048]    Materials utilized in the jacket  30  and/or the material strips  46  may have additives which influence friction, traction and wear properties. These additives may include but are not limited to small molecule additives such as liquids, oils, paraphinic waxes, ionic liquids, fire retardants etc. Other additives could also include blends of other polymers, or particulate additives such as inorganics (clay, glass, etc.) or organics (rubber, etc.). Any combination of additives can be incorporated at a range of total additive concentration from 0.001 wt. % to 50 wt. %; more specifically 0.01 wt. % to 25 wt. % and even more specifically 0.01 wt. % to 15 wt. %. 
         [0049]    In some embodiments, as shown in  FIG. 4 , the material strips  46  are applied over the traction surface  36 , and may be added during the extrusion process used to form the jacket  30  over the cords  28 . Alternatively, the material strips  46  may be imparted to the traction surface  36  during a mold wheel operation, after extrusion of the jacket  30 . Referring now to  FIG. 5 , in some embodiments, a groove  48  is formed in the jacket  30 , either during extrusion or in a post-extrusion process. An additive material  54  is added into the groove  48  to change the belt  16  performance, reducing wear of the belt  16 , compared to a belt without the additive material  54  of the material strips  46 . The additive material  54  is added in a post extrusion process, such as thermal fusion or adhesion of a secondary tape or fabric including the additive material  54  to the groove  48 . This allows for standardization of the jacket  30  manufacturing process and also the manufacturing process of the additive material  54 . The additive material  54  may include fluoropolymers, polyesters or other thermoplastic materials. Additional exemplary materials include uncoated or coated fabrics, such as Kevlar, graphite, urethane, rubber or other materials to modify friction properties of the belt  16 . Further, in some embodiments, the additive material  54  may be utilized not only at the traction surface  36  but at the back surface  38 . 
         [0050]    Referring now to  FIG. 6 , in some embodiments, the groove  48  may have an interlocking notch  56  extending outwardly from the groove  48 , into which the additive material  54  may be inserted to lock the additive material  54  in place at the groove  48 . In an alternate embodiment, the locking feature of  54  is preformed in the second material and integrated into the belt  16  during the primary extrusion operation of the jacket material. 
         [0051]    In another embodiment, as illustrated in  FIG. 7 , the belt  16  may include undercuts  58  where material is removed from the jacket  30  in locations where high degrees of wear are predicted. Such configurations move high pressure and/or slip to other locations along the belt  16 . In addition, belt  16  thickness may be enhanced in other regions, such as belt width ends  60 . Wear in the normal wear track, such as at cords  28   b  and  28   i  is deferred until the additional material is removed via wear from the belt width ends  60 . Further, the material added at the belt width ends  60  may be a wear resistant material or fabric. Such modifications may be through the extrusion process of the jacket  30  and/or via a secondary process. In some embodiments, such as shown in  FIG. 8 , the additive materials  54  may be wrapped around an edge surface  62  of the belt  16  from the traction surface  36  to the back surface  38 . 
         [0052]    The configurations disclosed herein allow for modifications to a base belt  16  configuration to address performance issues such as wear, slip and noise through the use of added features such as material strips  46  and additive materials  54 . These features may be added without changing the manufacturing processes of the baseline belt  16 . 
         [0053]    While the disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Rather, the disclosure 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 disclosure. Additionally, while various embodiments have been described, it is to be understood that aspects of the disclosure may include only some of the described embodiments. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.