Patent Publication Number: US-10773926-B2

Title: Elevator belt with additive layer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of 62/480,864, filed Apr. 3, 2017 which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Embodiments disclosed herein relate to elevator systems, and more particularly to load bearing members to suspend and/or drive elevator cars of an elevator system. 
     Elevator systems are useful for carrying passengers, cargo, or both, between various levels in a building. Some elevators are traction based and utilize load bearing members such as belts for supporting the elevator car and achieving the desired movement and positioning of the elevator car. 
     Where a belt is used as a load bearing member, a plurality of tension elements, or cords, are embedded in a common jacket. The jacket retains the cords in desired positions and provide a frictional load path. In an exemplary traction elevator system, a machine drives a traction sheave with which the belts interact to drive the elevator car along a hoistway. Belts typically utilize tension members formed from steel elements, but alternatively may utilize tension members formed from synthetic fibers or other materials, such as carbon fiber composites. 
     BRIEF DESCRIPTION 
     In one embodiment, a belt for an elevator system includes a plurality of tension members arranged along a belt width and extending longitudinally along a length of the belt, a jacket material at least partially encapsulating the plurality of tension members, and a primary overlay layer applied to one or more of the plurality of tension members or at least a portion of the jacket material. 
     Additionally or alternatively, in this or other embodiments the primary overlay layer is formed from a non-woven carbon nanotube sheet. 
     Additionally or alternatively, in this or other embodiments the carbon nanotubes are multi-walled carbon nanotubes. 
     Additionally or alternatively, in this or other embodiments the primary overlay layer is formed from an intrumenscent material. 
     Additionally or alternatively, in this or other embodiments a secondary overlay layer is applied over the primary overlay layer. 
     Additionally or alternatively, in this or other embodiments the secondary overlay layer defines a traction surface of the belt. 
     Additionally or alternatively, in this or other embodiments the secondary overlay layer is an elastomeric material. 
     Additionally or alternatively, in this or other embodiments the primary overlay layer is formed at the plurality of tension members by one or more of wrapping, dipping, spraying, laminating or pultrusion process. 
     Additionally or alternatively, in this or other embodiments the primary overlay layer is configured to improve thermal performance of the belt. 
     In another embodiment, an elevator system includes a hoistway, an elevator car located in the hoistway and movable therein, and a belt operably connected to the elevator car to suspend and/or drive the elevator car along the hoistway. The belt includes a plurality of tension members arranged along a belt width and extending longitudinally along a length of the belt, a jacket material at least partially encapsulating the plurality of tension members, and a primary overlay layer applied to one or more of the plurality of tension members or at least a portion of the jacket material. 
     Additionally or alternatively, in this or other embodiments the primary overlay layer is formed from a non-woven carbon nanotube sheet. 
     Additionally or alternatively, in this or other embodiments the carbon nanotubes are multi-walled carbon nanotubes. 
     Additionally or alternatively, in this or other embodiments the primary overlay layer is formed from an intrumenscent material. 
     Additionally or alternatively, in this or other embodiments a secondary overlay layer is applied over the primary overlay layer. 
     Additionally or alternatively, in this or other embodiments the secondary overlay layer defines a traction surface of the belt. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  is a schematic illustration of an embodiment of an elevator system; 
         FIG. 2  is a schematic cross-sectional view of an embodiment of an elevator system belt; 
         FIG. 3  is a cross-sectional view of an embodiment of a tension member for an elevator belt; 
         FIG. 4  is a another cross-sectional view of an embodiment of a tension member for an elevator belt; 
         FIG. 5  is another cross-sectional view of an embodiment of an elevator system belt; and 
         FIG. 6  is yet another cross-sectional view of an embodiment of an elevator system belt. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     Shown in  FIG. 1 , is a schematic view of an exemplary traction elevator system  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. 
     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  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 . 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 . 
     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  or only one side of the one or more belts  16  engages the one or more sheaves  18 . The embodiment of  FIG. 1  shows a  1 : 1  roping arrangement in which the one or more belts  16  terminate at the car  12  and counterweight  22 , while other embodiments may utilize other roping arrangements. 
     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 . 
       FIG. 2  provides a cross-sectional schematic of an exemplary belt  16  construction or design. The belt  16  includes a plurality of tension members  24  extending longitudinally along the belt  16  and arranged across a belt width  26 . The tension members  24  are at least partially enclosed in a jacket material  28  to restrain movement of the tension members  24  in the belt  16  and to protect the tension members  24 . The jacket material  28  defines a traction side  30  configured to interact with a corresponding surface of the traction sheave  52 . Exemplary materials for the jacket material  28  include the elastomers of thermoplastic and thermosetting polyurethanes, polyamide, thermoplastic polyester elastomers, and rubber, for example. Other materials may be used to form the jacket material  28  if they are adequate to meet the required functions of the belt  16 . For example, a primary function of the jacket material  28  is to provide a sufficient coefficient of friction between the belt  16  and the traction sheave  52  to produce a desired amount of traction therebetween. The jacket material  28  should also transmit the traction loads to the tension members  24 . In addition, the jacket material  28  should be wear resistant and protect the tension members  24  from impact damage, exposure to environmental factors, such as chemicals, for example. 
     The belt  16  has a belt width  26  and a belt thickness  32 , with an aspect ratio of belt width  26  to belt thickness  32  greater than one. The belt  16  further includes a back side  34  opposite the traction side  30  and belt edges  36  extending between the traction side  30  and the back side  34 . 
     As shown in  FIG. 3 , in some embodiments, the tension members  24  are cords formed from a plurality of steel wires  38 , which may be arranged into strands  40 . Alternatively, referring to  FIG. 4 , the tension members  24  may be formed from synthetic fibers or from a composite constructions, such as a plurality of load-carrying fibers  42  disposed in a matrix material  44 . 
     Exemplary load carrying fibers  42  include, but are not limited to, carbon, glass, aramid, nylon, and polymer fibers, for example. Each of the load carrying fibers  42  may be substantially identical or may vary. In addition, the matrix material  44  may be formed from any suitable material, such as polyurethane, vinylester, and epoxy for example. The materials of the load carrying fibers  42  and the matrix material  44  are selected to achieve a desired stiffness and strength of the tension member  24 . 
     The tension member  24  may be formed as thin layers, in some embodiments by a pultrusion process. In a standard pultrusion process, the load carrying fibers  42  are impregnated with the matrix material  44  and are pulled through a heated die and additional curing heaters where the matrix material  44  undergoes cross linking. A person having ordinary skill in the art will understand that controlled movement and support of the pulled load carrying fibers  42  may be used to form a desired linear or curved profile of the tension member  24 . In an exemplary embodiment, the tension member  24  has a cross-sectional thickness of about 0.5 millimeters to about 5 millimeters. Further, in some embodiments the tension member  24  has a circular cross-section, while in other embodiments the tension member  24  may have other cross-sectional shapes, such as rectangular or oval. Further, in some embodiments, the tension members  24  may include a tension element member coating layer  46  to, for example, promote adhesion with the jacket material  28 . 
     While eight tension members  24  are illustrated in the embodiment of  FIG. 2 , other embodiments may include other numbers of tension members  24 , for example, 6, 10 or 12 tension members  24 . Further, while the tension members  24  of the embodiment of  FIG. 2  are substantially identical, in other embodiments, the tension members  24  may differ from one another in number of wires  38 , materials or arrangement. 
     The belt  16  includes one or more primary overlay layers  48  formed from a carbon nanotube sheet. In some embodiments, the carbon nanotube sheet is a non-woven carbon nanotube sheet, and further may be a non-woven sheet of multi-walled carbon nanotubes. The primary overlay layer  48  is configured to enhance fire and thermal performance of the belt  16 , protecting the tension members  24  and the jacket material  28  during a thermal event. While in some embodiments, the primary overlay layer  48  is formed from a carbon nanotube sheet. 
     In other embodiments the primary overlay layer may be formed from an intrumenscent material to promote char formation and therefore retards heat conduction and flame formation and spread. Examples of intrumenscent materials include a paper formed from such a material, or a coating including an intrumenscent material. Intumenscent coatings may include three halogen-free flame-retardant additives: an acid source such as phase II ammonium polyphosphate, a carbon source such as pentaerythritol, and a blowing agent such as melamine mixed together with flame-retardant fillers and a polymer binder. Aluminum hydroxide (Al(OH) 3 ) and magnesium hydroxide (Mg(OH) 2 ) are examples of flame-retardant fillers. 
     The primary overlay layer  48  may be applied entirely around a perimeter of the jacket material  28 , or on selected surfaces, such as the traction side  30 , the back side  34  and/or the belt edges  36 . A secondary overlay layer  54  is applied over the primary overlay layer  48  to protect the primary overlay layer  48  from wear or other damage during operation of the elevator system  10 . In some embodiments, the secondary overlay layer  54  is applied at the traction side  30  and the back side  34 , while in other embodiments the secondary overlay layer  54  is selectably applied to the traction side  30 , the back side  34  and/or the belt edges  36 . The second overlay layer  54  may be formed from the same material as the jacket material  38  or alternatively may be formed from a different material to enhance traction and wear performance of the belt  16 . 
     Referring now to  FIG. 5 , in some embodiments the primary overlay layer  48  may be applied to the tension members  24  to protect the tension members  24  directly. Such application of the primary overlay layer  48  may be performed by, for example, wrapping the tension members  24 , applying a liquid or solid coating of primary overlay layer  48  to the tension members  24  via, for example, dip or spray processes, or by a lamination process. After application of the primary overlay layer  48  is applied to the tension members  24 , subsequent processes such as application of the jacket material  38  are performed to complete the belt  16 . Further, the application of the primary overlay layer  48  may be incorporated into a pultrusion process used for formation of the tension members  24 . 
     Referring now to  FIG. 6 , in some embodiments the primary overlay layer  48  is applied to both the tension members  24  and to the jacket material  38  at, for example, the traction side  30  and the back side  34 . 
     Use of the primary overlay layer  48  improves fire and thermal performance of the belt  16  and maintains friction and traction performance of the belt  16 , especially when used in conjunction with the secondary overlay layer  54 . 
     The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.