Abstract:
A belted elevator system ( 10 ) includes a hoistway ( 14 ) and an elevator car ( 12 ) suspended in the hoistway ( 14 ) via a suspension member ( 16 ) and drivable along the hoistway ( 14 ). The suspension member ( 16 ) is routed over a plurality of sheaves ( 18 ). A sheave ( 18 ) of the plurality of sheaves includes a shaft ( 36 ) defining a central axis of the sheave ( 18 ), the sheave ( 18 ) rotatable about the central axis. A sheave outer member ( 38 ) is operably connected to the shaft ( 36 ) and rotatable about the central axis. The sheave outer member ( 38 ) includes a sheave outer surface ( 44 ) interactive with the suspension member ( 16 ). The sheave outer member ( 38 ) is formed from a molded plastic material.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to elevator systems. More particularly, the present disclosure relates to sheave configurations for elevator systems. 
         [0002]    A typical elevator system includes an elevator car that moves along a hoistway. The elevator car is suspended in the hoistway and driven along the hoistway by one or more tension members, such as a coated steel belt. The coated steel belt is operably connected to the elevator car, and driven by a motor to propel the elevator car along the hoistway. Coated steel belts in particular include a plurality of wires located at least partially within a jacket material. The plurality of wires is often arranged into one or more strands and the strands are then arranged into one or more cords. In an exemplary belt construction, a plurality of cords is typically arranged equally spaced within a jacket in a longitudinal direction. 
         [0003]    The motor drives a sheave, in this case a traction sheave, over which the coated steel belt is routed. The belt gains traction at the traction sheave, such that rotation of the traction sheave consequently drives movement of the elevator car. The coated steel belt is then routed over one or more idler or deflector sheaves to guide the belt between the traction sheave and the elevator car. The idler or deflector sheaves are utilized to route the tension member and to maintain a desired tension thereat. Such sheaves are typically formed from steel, with a coating, such as a nickel plating, applied to the outer sheave surface that is interactive with the tension member. Due to the high surface energy of the metal surface, the tension member to sheave interface can generate noise as a result of strain energy buildup and release in the jacket. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    In one embodiment, a sheave for a belted elevator system includes a shaft defining a central axis of the sheave, the sheave rotatable about the central axis. A sheave outer member is operably connected to the shaft via at least one bearing and rotatable about the central axis. The sheave outer member is interactive with a tension member of the elevator system. The sheave outer member is formed from a molded plastic material. 
         [0005]    Alternatively or additionally, in this or other embodiments the sheave outer member is supported at the bearing by a metallic support member. 
         [0006]    Alternatively or additionally, in this or other embodiments the metallic support member is a tubular insert disposed radially inboard of the sheave outer surface. 
         [0007]    Alternatively or additionally, in this or other embodiments the metallic support member is embedded in the sheave outer member. 
         [0008]    Alternatively or additionally, in this or other embodiments the metallic support member comprises a plurality of metallic rings molded into the sheave outer member. 
         [0009]    Alternatively or additionally, in this or other embodiments the sheave outer member is formed from one or more of filled or unfilled polymers including but not limited to an ultra high molecular weight polyethylene, nylon, polyethylene terephthalate (PET) material, or an acetal resin material such as polyoxymethylene. 
         [0010]    Alternatively or additionally, in this or other embodiments the sheave outer member includes a sheave outer surface interactive with the tension member, the sheave outer surface including one or more dimples, bumps, ridges, slits, depressions, or roughness elements configured to inhibit noise. 
         [0011]    In another embodiment, a belted elevator system includes a hoistway and an elevator car suspended in the hoistway via a suspension member and drivable along the hoistway. The suspension member is routed over a plurality of sheave. A sheave of the plurality of sheaves includes a shaft defining a central axis of the sheave, the sheave rotatable about the central axis. A sheave outer member is operably connected to the shaft and rotatable about the central axis. The sheave outer member includes a sheave outer surface interactive with the suspension member. The sheave outer member is formed from a molded plastic material. 
         [0012]    Alternatively or additionally, in this or other embodiments the sheave outer member is supported at the shaft by a metallic support member. 
         [0013]    Alternatively or additionally, in this or other embodiments the metallic support member is one of a tubular insert disposed radially inboard of the sheave outer surface or a plurality of metallic rings molded into the sheave outer member. 
         [0014]    Alternatively or additionally, in this or other embodiments the metallic support member is embedded in the sheave outer member. 
         [0015]    Alternatively or additionally, in this or other embodiments the sheave outer member is formed from one or more of filled or unfilled polymers including but not limited to an ultra high molecular weight polyethylene, nylon, polyethylene terephthalate (PET) material, or an acetal resin material such as polyoxymethylene (POM). 
         [0016]    Alternatively or additionally, in this or other embodiments the sheave outer surface includes one or more dimples, bumps, ridges, slits, depressions, or roughness elements configured to inhibit noise. 
         [0017]    In yet another embodiment, a sheave assembly for a belted elevator system includes a shaft defining a central axis of the sheave assembly and a plurality of sheaves disposed along the shaft. Each sheave of the plurality of sheaves is rotatable about the central axis and includes a sheave outer member operably connected to the shaft via at least one bearing and rotatable about the central axis. The sheave outer member is interactive with a tension member of the elevator system. The sheave outer member is formed from a molded plastic material and includes one or more dimples, bumps, ridges, slits, depressions, or roughness elements configured to inhibit noise. 
         [0018]    Alternatively or additionally, in this or other embodiments a first sheave of the plurality of sheaves utilizes a first configuration of noise inhibiting features and a second sheave of the plurality of sheaves utilizes a second configuration of noise inhibiting features, different from the first configuration. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1A  is a schematic of an exemplary elevator system having a 1:1 roping arrangement; 
           [0020]      FIG. 1B  is a schematic of another exemplary elevator system having a different roping arrangement; 
           [0021]      FIG. 1C  is a schematic of another exemplary elevator system having a cantilevered arrangement; 
           [0022]      FIG. 2  is a schematic view of an embodiment of an elevator belt for an elevator system; 
           [0023]      FIG. 3  is a cross-sectional view of an embodiment of a cord for an elevator belt; 
           [0024]      FIG. 4  is a partially exploded view of an embodiment of a sheave for an elevator system; 
           [0025]      FIG. 5  is a perspective view of an embodiment of a sheave outer surface having exemplary noise inhibiting features; 
           [0026]      FIG. 6  is a partially exploded view of another embodiment of a sheave for an elevator system; 
           [0027]      FIG. 7  is a cross-sectional view of an embodiment of a sheave for an elevator system; 
           [0028]      FIG. 8  is a cross-sectional view of another embodiment of a sheave for an elevator system; 
           [0029]      FIG. 9  is a cross-sectional view of yet another embodiment of a sheave for an elevator system; 
           [0030]      FIG. 10  is a cross-sectional view of an embodiment of a sheave assembly for an elevator system; and 
           [0031]      FIG. 11  is a cross-sectional view of another embodiment of a sheave assembly for an elevator system. 
       
    
    
       [0032]    The detailed description explains the invention, together with advantages and features, by way of examples with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    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. It is to be appreciated that while the embodiments herein are described as applied to coated steel belts, it is to be appreciated that the disclosure herein may similarly be applied to steel ropes, either coated or uncoated. 
         [0034]    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 traction sheave  24 . The traction sheave  24  is driven by a machine  26 . Movement of the traction sheave  24  by the machine  26  drives, moves and/or propels (through traction) the one or more belts  16  that are routed around the traction sheave  24 . 
         [0035]    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 . 
         [0036]      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 cantilevered type elevator. The present invention could be used on elevator systems other than the exemplary types shown in  FIGS. 1A, 1B and 1C . 
         [0037]      FIG. 2  provides a schematic of a belt construction or design. Each belt  16  is constructed of a plurality of wires  28  (e.g. twisted into one or more strands  30  and/or cords  32  as shown in  FIG. 3 ) in a jacket  34 . As seen in  FIG. 2 , the belt  16  has an aspect ratio greater than one (i.e. belt width is greater than belt thickness). The belts  16  are 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 . The jacket  34  could be any suitable material, including a single material, multiple materials, two or more layers using the same or dissimilar materials, and/or a film. In one arrangement, the jacket  34  could be a polymer, such as an elastomer, applied to the cords  32  using, for example, an extrusion or a mold wheel process. In another arrangement, the jacket  34  could be a woven fabric that engages and/or integrates the cords  32 . As an additional arrangement, the jacket  34  could be one or more of the previously mentioned alternatives in combination. 
         [0038]    The jacket  34  can substantially retain the cords  32  therein. The phrase substantially retain means that the jacket  34  has sufficient engagement with the cords  32  to transfer torque from the machine  26  through the jacket  34  to the cords  32  to drive movement of the elevator car  12 . The jacket  34  could completely envelop the cords  32  (such as shown in  FIG. 2 ), substantially envelop the cords  24 , or at least partially envelop the cords  32 . 
         [0039]    Referring now to  FIG. 4 , in some embodiments, the sheave  18  includes a shaft  36  and a sleeve  38 , with a tubular sheave insert  40  and a bearing  42  interposed between the sleeve  38  and the shaft  36  to transfer loads therebetween. The sheave insert  40  is formed from, for example, a metal or composite material having a high lateral stiffness and a high bending stiffness. The sleeve  38 , however, is formed from a plastic material, for example, filled or unfilled polymers including but not limited to an ultra high molecular weight polyethylene, nylon, polyethylene terephthalate (PET) material, or an acetal resin material such as polyoxymethylene (POM). The sleeve  38  is secured to the sheave insert  40  to prevent lateral and circumferential sliding between the two components. For example, the sleeve  38  may be molded onto the sheave insert  40 , or may be pressed onto the sheave insert  40  with an interference fit. In other embodiments, the sleeve  38  is secured to the sheave insert  40  via mechanical fasteners such as a plurality of bolts installed through noise inhibiting holes in the sleeve  38 . 
         [0040]    The plastic sleeve  38  allows for tuning of the sheave  18  structure to reduce noise. The plastic material typically has a lower surface energy than a steel material utilized in a typical sheave, thus more easily enabling a low friction interface between the sheave  18  and belt  16  at a sheave outer surface  44  of the sleeve  38 . In some embodiments, the outer surface  44  is crowned. Further, the sheave  18  may include multiple sheave outer surfaces  44  to interface with multiple belts  16 . For example, the sheave  18  may have three sheave outer surfaces  44  arranged across a width of the sheave  18  to interface with three belts  16 . Further, as shown in  FIG. 5 , the plastic sleeve  38  allows for optimally choosing friction and surface roughness of the plastic sleeve  38 , by molding noise inhibiting features such as the shown dimples  46 , or other features such a bumps, ridges, slits, depressions, roughness elements or the like, into the plastic sleeve  38  to reduce noise between the belt  16  and the sheave  18 . 
         [0041]    Referring now to  FIG. 6 , in some embodiment if load conditions allow, the sheave  18  may be formed with the plastic sleeve  38 , but without the tubular sheave insert  40  further saving weight and material and thus cost. In embodiments with or without the tubular sheave insert  40 , the sleeve  38  may include other reinforcement of metal or composite materials to strengthen the sheave  18  and allow for effective load transfer to the bearing  42 , as shown in  FIGS. 7-9 . In the embodiment of  FIG. 7 , reinforcing rings  48  formed from, for example, steel, are inserted into the plastic sleeve  38 . The reinforcing rings  48  are positioned at a same axial position as the bearing  42  for effective load transfer from the sleeve  38  to the bearing  42 . In some embodiments, the reinforcing rings  48  are molded into the sleeve  38 , while in other embodiments the reinforcing rings  48  are installed in the sleeve  38  after sleeve  38  molding is completed. In some embodiments, multiple reinforcing rings  48  are utilized, as shown in  FIG. 7 , while in other embodiments such as those of  FIG. 7A , a single reinforcing ring  48  extends across a width of the sheave  18 . 
         [0042]    Referring now to  FIGS. 8 and 9 , embodiments are illustrated wherein the bearings  42  are external to the sleeve  38 , and the shaft  36  rotates with the sleeve  38  as the belt  16  passes over the sleeve  38 . This is contrasted with other embodiments, such as those of  FIG. 6 , where the shaft  36  is fixed relative to the sleeve  38 , and the sleeve  38  rotates about the shaft  36  as the belt  16  passes across the sleeve  38 . The shaft  36  is formed from plastic, and in some embodiments is integral to the sleeve  38 . The bearings  42  are located at the shaft  36 , and the shaft  36  is reinforced with either a shaft reinforcing ring  50  as in  FIG. 8 , or a shaft reinforcing rod  52  as in  FIG. 9 . As with the embodiment of  FIG. 6 , the shaft reinforcing ring  50  or the shaft reinforcing rod  52  may be molded into the sleeve  38  or alternatively installed in the sleeve  38  after molding is completed. 
         [0043]    Referring to  FIG. 10 , a sheave assembly  54  may be constructed utilizing a plurality of sheaves  18 , arranged along the shaft  36 . In some embodiments, a bearing  42  is located at each sheave  18  of the plurality of sheaves. Alternatively, as shown in  FIG. 11 , bearings  46  are located at end sheaves  18  of the sheave assembly  54 , and the remaining sheaves  18  are connected to the end sheaves  18  via a connecting means  56 , such as a pin, fastener, weld or adhesive. Such modular construction of the sheave assembly  54  allows individual sheaves  18  to be tuned differently based on specific operating conditions by utilizing different configurations of noise inhibiting features, utilizing different materials, different reinforcing means or the like. 
         [0044]    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.