Patent Publication Number: US-9902594-B2

Title: Elevator rope and elevator apparatus that uses same

Description:
TECHNICAL FIELD 
     The present invention relates to an elevator rope that has: a fiber core that is disposed centrally; and a plurality of strands that are formed by twisting together a plurality of steel wires, and to an elevator apparatus that uses the same. 
     BACKGROUND ART 
     In conventional high-strength wire ropes, an outer periphery of a steel core rope is coated with an elastomer, and a plurality of steel strands are twisted together on an outer circumference of the elastomer (see Patent Literature 1, for example). 
     In other conventional wire ropes, a coating is disposed on an outer circumference of a core rope. Pores for issuing small amounts of oil that is contained in the core rope over a long time are disposed on the coating (see Patent Literature 2, for example). 
     In addition, in conventional elevator ropes, a core rope that is formed by twisting three core rope strands together with each other is disposed centrally. Each of the core rope strands is constituted by a number of yarns that are formed by bundling fibers. An outer circumference of the core rope is coated by a resin core rope coating body. A plurality of steel strands are twisted together on an outer circumference of the core rope coating body. Each of the steel strands is formed by twisting together a plurality of steel wires (see Patent Literature 3, for example). 
     CITATION LIST 
     Patent Literature 
     
         
         [Patent Literature 1] 
       
    
     Japanese Patent No. 2992783 (Gazette)
     [Patent Literature 2]   

     Japanese Utility Model Laid-Open No. HEI 7-43870 (Gazette)
     [Patent Literature 3]   

     International Publication No. (WO) 2010/143249 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     In conventional ropes with steel cores such as that disclosed in Patent Literature 1, the configuration is such that occupied area of steel portions relative to rope diameter is maximized in order to increase strength by increasing effective cross-sectional area. Because of that, the configuration is such that the core rope has: a steel core strand that is disposed centrally therein; and a plurality of steel inner layer strands that are twisted together on an outer circumference of the core strand. However, in a core rope of this kind, portions that contain rope grease are limited, making it difficult to include the amount of oil that is conventionally required. Furthermore, since the core rope is configured using only steel wire, overall mass is increased. 
     In conventional wire ropes such as that disclosed in Patent Literature 2, compressive forces at a level that is accompanied by deformation are not applied when the strands are twisted together onto the outer circumference of the core rope, and the core rope is not tightened except in a step of twisting together the core rope itself. Because of that, more structural gaps than necessary can be expected to remain inside the core rope. 
     In conventional elevator ropes such as that disclosed in Patent Literature 3, because the core rope is constituted by fibers, there has been a risk that the fibers may melt and break due to heat from a molding machine as the core rope coating body is coated onto the outer circumference of the core rope. Furthermore, because the core rope is not tightened except during the step of twisting the core rope strands together, structural gaps remain inside the core rope, giving rise to deformation (loss of resilience) and reductions in diameter in the core rope due to extensive use, and contact pressure among the steel strands is thereby increased, giving rise to abrasion and wire breakages in the steel wires. 
     The present invention aims to solve the above problems and an object of the present invention is to provide an elevator rope and an elevator apparatus that uses the same that can suppress increases in mass and that can also suppress breakage of fibers that constitute a fiber core and deformation and reductions in diameter of the fiber core, while ensuring sufficient rope grease content. 
     Means for Solving the Problem 
     In order to achieve the above object, according to one aspect of the present invention, there is provided an elevator rope including: an inner layer rope that includes: an inner layer rope fiber core; a plurality of inner layer strands that are twisted together on an outer circumference of the inner layer rope fiber core; and a resin inner layer rope coating body that is coated onto an outer circumference; and a plurality of steel outer layer strands that are twisted together on an outer circumference of the inner layer rope, wherein the inner layer strands include: an inner layer strand fiber core that is disposed centrally; and a plurality of steel inner layer strand wires that are twisted together on an outer circumference of the inner layer strand fiber core. 
     According to another aspect of the present invention, there is provided an elevator apparatus including: a hoisting machine that includes a driving sheave; an elevator rope that includes: an inner layer rope; a plurality of steel outer layer strands that are twisted together on an outer circumference of the inner layer rope, the elevator rope being wound onto the driving sheave; and a car that is suspended by the elevator rope, and that is raised and lowered by the hoisting machine, wherein: the inner layer rope includes: an inner layer rope fiber core; a plurality of inner layer strands that are twisted together on an outer circumference of the inner layer rope fiber core; and a resin inner layer rope coating body that is coated onto an outer circumference; and the inner layer strands include: an inner layer strand fiber core that is disposed centrally; and a plurality of steel inner layer strand wires that are twisted together on an outer circumference of the inner layer strand fiber core. 
     Effects of the Invention 
     Because the inner layer strands are twisted together on the outer circumference of the inner layer rope fiber core, and inner layer strand fiber cores are disposed centrally in the inner layer strands, and inner layer strand wires that are made of steel are twisted together on the outer circumference of the inner layer strand fiber core, the elevator rope and the elevator apparatus that uses the same according to the present invention can suppress increases in mass and can also suppress breakage of fibers that constitute the fiber cores and deformation and reductions in diameter of the fiber core, while ensuring sufficient rope grease content. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration diagram that shows an elevator apparatus according to Embodiment 1 of the present invention; 
         FIG. 2  is a cross section of an elevator rope from  FIG. 1 ; 
         FIG. 3  is a cross section of an elevator rope according to Embodiment 2 of the present invention; and 
         FIG. 4  is a cross section of an elevator rope according to Embodiment 3 of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments for implementing the present invention will now be explained with reference to the drawings. 
     Embodiment 1 
       FIG. 1  is a configuration diagram that shows an elevator apparatus according to Embodiment 1 of the present invention. In the figure, a machine room  22  is disposed in an upper portion of a hoistway  21 . A machine base  23  is installed inside the machine room  22 . A hoisting machine  24  is supported on the machine base  23 . The hoisting machine  24  has a driving sheave  25  and a hoisting machine main body  26 . The hoisting machine main body  26  has: a hoisting machine motor that rotates the driving sheave  25 ; and a hoisting machine brake that brakes the rotation of the driving sheave  25 . 
     A deflecting sheave  27  is mounted onto the machine base  23 . A plurality of elevator ropes  28  (only one is shown in the figure) that function as a suspending means are wound around the driving sheave  25  and the deflecting sheave  27 . A plurality of rope grooves into which the elevator ropes  28  are inserted are disposed on an outer circumference of the driving sheave  25 . 
     A car  29  and a counterweight  30  are suspended inside the hoistway  21  by the elevator ropes  28  so as to be raised and lowered inside the hoistway  21  by the hoisting machine  24 . A pair of car guide rails  31  that guide raising and lowering of the car  29  and a pair of counterweight guide rails  32  that guide raising and lowering of the counterweight  30  are installed inside the hoistway  21 . A safety device  33  that makes the car  29  perform an emergency stop by engaging with the car guide rails  31  is mounted onto the car  29 . 
       FIG. 2  is a cross section of an elevator rope  28  from  FIG. 1 . The elevator rope  28  has: an inner layer rope  1 ; and a plurality of (in this example, eight) outer layer strands  2  that are twisted together on an outer circumference of the inner layer rope  1 . The outer layer strands  2  are positioned in an outermost layer of the elevator rope  28  so as to be exposed externally. 
     The inner layer rope  1  has: an inner layer rope fiber core  3  that is disposed centrally; a plurality of (in this example, eight) inner layer strands  4  that are twisted together directly onto an outer circumference of the inner layer rope fiber core  3 ; and a resin inner layer rope coating body  5  that is coated onto an outer circumference. 
     The inner layer rope fiber core  3  is configured by twisting fibers together. A rope grease is impregnated into the inner layer rope fiber core  3 . 
     Each of the inner layer strands  4  has: an inner layer strand fiber core  6  that is disposed centrally; a plurality of (in this example, twelve) first inner layer strand wires (intermediate wires)  7  that are twisted together on an outer circumference of the inner layer strand fiber core  6 ; and a plurality of (in this example, twelve) second inner layer strand wires (outer layer wires)  8  that are twisted together on an outer circumference of the layer of first inner layer strand wires  7 . 
     The inner layer strand fiber cores  6  are configured by twisting fibers together. A rope grease is impregnated into all of the inner layer strand fiber cores  6 . 
     The first and second inner layer strand wires  7  and  8  are all steel wires. A diameter of the second inner layer strand wires  8  is smaller than a diameter of the inner layer strand fiber cores  6 , and larger than a diameter of the first inner layer strand wires  7 . In other words, the diameter of the first inner layer strand wires  7  is smaller than the diameter of the second inner layer strand wires  8 . 
     A resin that has a certain amount of hardness, such as polyethylene or polypropylene, for example, is used as a material for the inner layer rope coating body  5 . The inner layer rope coating body  5  is interposed between adjacent outer layer strands  2 , between adjacent inner layer strands  4 , and also between the outer layer strands  2  and the inner layer strands  4 . 
     Each of the outer layer strands  2  has: a first outer layer strand wire (a core wire)  9  that is disposed centrally; a plurality of (in this example, nine) second outer layer strand wires (intermediate wires)  10  that are twisted together on an outer circumference of the first outer layer strand wire  9 ; and a plurality of (in this example, nine) third outer layer strand wires (outer layer wires)  11  that are twisted together on an outer circumference of the layer of second outer layer strand wires  10 . 
     The first through third outer layer strand wires  9  through  11  are all steel wires. A diameter of the third outer layer strand wires  11  is smaller than a diameter of the first outer layer strand wires  9 , and larger than a diameter of the second outer layer strand wires  10 . In other words, the diameter of the second outer layer strand wires  10  is smaller than the diameter of the third outer layer strand wires  11 . 
     A diameter of the inner layer strands  4  is smaller than a diameter of the outer layer strands  2 . In this example, the diameter of the inner layer strands  4  is less than or equal to one half of the diameter of the outer layer strands  2 . Furthermore, the inner layer strands  4  are equal in number to the outer layer strands  2 . 
     The diameters of the inner layer strand wires  7  and  8  are smaller than the diameters of any of the outer layer strand wires  9 ,  10 , and  11 . The tensile strength of the inner layer strand wires  7  and  8  is higher than the tensile strength of any of the outer layer strand wires  9 ,  10 , and  11 . 
     In an elevator rope  28  of this kind, because the inner layer rope fiber core  3  is disposed centrally in the inner layer rope  1  and the inner layer strand fiber cores  6  are disposed centrally in each of the inner layer strands  4 , rope grease content can be increased compared to inner layer ropes that are configured using only the steel wire. 
     By increasing the cross-sectional area of the fiber portion and reducing the cross-sectional area of the steel wire, increases in the unit mass of the elevator rope  28  can be suppressed. Specifically, increases in unit mass due to the inner layer strands  4  can be kept to within fifteen percent compared to ropes with fiber cores in which the portion occupied by the inner layer strands  4  is instead occupied by the fiber core. The elevator rope  28  according to Embodiment 1 can thereby be used instead of elevator ropes that are used in existing elevator apparatuses, for example, without modification. 
     In addition, because the inner layer strands  4  are disposed between the inner layer rope fiber core  3  and the inner layer rope coating body  5 , and the inner layer strand wires  7  and  8  are disposed around the outer circumferences of the inner layer strand fiber cores  6 , the fiber cores  3  and  6  are prevented from being fused and cut by the high-temperature resin when applying the inner layer rope coating body  5 . 
     Furthermore, because the inner layer rope fiber core  3  is tightened when the inner layer strands  4  are twisted together, structural gaps inside the inner layer rope fiber core  3  are reduced significantly, enabling reductions in diameter due to deformation (loss of resilience) of the inner layer rope  1  over periods of extended use to be suppressed. Thus, increases in contact pressure among the outer layer strands  2  due to reductions in diameter are prevented, enabling abrasion of the outer layer strands  2  to be suppressed. 
     By using a resin such as polyethylene or polypropylene, for example, that has self-lubricating properties as the material for the inner layer rope coating body  5 , deterioration in lubricity between the inner layer strands  4  and the outer layer strands  2  is prevented if the rope grease dries up due to an extended period of use, enabling deterioration in strength due to wire abrasion or core rope abrasion to be suppressed. 
     In addition, by making the number of inner layer strands less than or equal to eight, manufacturing using manufacturing equipment that is conventionally used in elevator manufacturing of the elevator is possible, enabling increases in the manufacturing costs of the elevator rope  28  to be suppressed. 
     Furthermore, because the diameters of the inner layer strand wires  7  and  8  are smaller than the diameters of any of the outer layer strand wires  9 ,  10 , and  11 , and the tensile strength of the inner layer strand wires  7  and  8  is higher than the tensile strength of any of the outer layer strand wires  9 ,  10 , and  11 , the inner layer strands  4  can be prevented from breaking before the outer layer strands  2 , enabling overall rope deterioration to be easily determined from the external appearance of the rope. 
     Now, if minute cracks arise in the inner layer rope coating body  5  due to an extended period of use, the rope grease is supplied to the outer layer strands  2  through the cracks. In contrast to that, if the thickness of the inner layer rope coating body  5  were too great, the rope grease might not be supplied, and the cross-sectional area of the inner layer rope fiber core  3  would be reduced, also reducing rope grease content. 
     In order to prevent direct contact between the inner layer strands  4  and the outer layer strands  2 , it is necessary for the inner layer rope coating body  5  to be interposed between the two. However, the thickness of the inner layer rope coating body  5  need only be in the order of one percent of the rope diameter in order to prevent direct contact. Because of that, allowing for manufacturing errors during coating application and laying of the outer layer strands  2 , it is preferable for the thickness of the inner layer rope coating body  5  that is interposed between the inner layer strands  4  and the outer layer strands  2  to be greater than or equal to one percent and less than or equal to two percent of an overall diameter of the elevator rope  28 . 
     By using fiber cores  3  and  6  that are made of a synthetic resin, internal gaps are reduced compared to natural fibers such as sisal that are commonly used as a core rope material in elevator ropes, further suppressing deformation (loss of resilience) over periods of extended use, and enabling corrosion in high-humidity environments to be suppressed. Thus, internal damage that was at risk of arising among the outer layer strands and between the outer layer strands  2  and the inner layer rope  1  can be more reliably prevented. 
     Embodiment 2 
     Next,  FIG. 3  is a cross section of an elevator rope  28  according to Embodiment 2 of the present invention. In Embodiment 2, a synthetic fiber round bar core (a solid core) that is made of polypropylene or polyethylene, for example, is used as an inner layer rope fiber core  12 . The round bar core is configured by twisting together three core strands  2  and applying pressure from an outer circumference. Each of the core strands is constituted by a number of yarns that are formed by bundling synthetic fibers. 
     Six inner layer strands  4  are twisted together onto an outer circumference of the inner layer rope fiber core  12 . In other words, the inner layer strands  4  are fewer in number than the outer layer strands  2 . The rest of the configuration is similar or identical to that of Embodiment 1. 
     In an elevator rope  28  of this kind, because a synthetic fiber round bar core is used as the inner layer rope fiber core  12 , packing density of the fibers in a central portion can be improved, enabling decreases in diameter due to deformation (loss of resilience) of the inner layer rope  1  over periods of extended use to be further suppressed. Thus, abrasion of the outer layer strands  2  can be further suppressed. 
     Because internal gaps are reduced in the inner layer rope fiber core  12  according to Embodiment 2 compared to the inner layer rope fiber core  3  according to Embodiment 1, the rope grease content is reduced. In contrast to that, the cross-sectional area of the inner layer strand fiber cores  6  can be increased by increasing the cross-sectional area of the inner layer strands  4  while reducing the number of the inner layer strands  4 , enabling the required rope grease content to be ensured. 
     Embodiment 3 
     Next,  FIG. 4  is a cross section of an elevator rope  28  according to Embodiment 3 of the present invention. In this example, outer layer strands  2  are compressed (by plastic working) from an outer circumference by a die during manufacturing. Cross-sectional shapes of outer layer wires  10  are thereby modified. The rest of the configuration is similar or identical to that of Embodiment 1. 
     According to a configuration of this kind, contact surface pressure between the rope grooves of the driving sheave  25  ( FIG. 1 ) and the elevator rope  28  can be reduced, enabling damage to the outer layer strands  2  to be suppressed while suppressing internal damage to the elevator rope  28 , and enabling additional extension of service life of the elevator rope  28  to be achieved. 
     Moreover, the shape of the third outer layer strand wires  11  according to Embodiment 2 may be modified in a similar or identical manner to Embodiment 3. 
     In Embodiment 2, the inner layer rope fiber core  12  is a round bar core, but the inner layer strand fiber cores  6  may also be synthetic fiber round bar cores. 
     In addition, the type of elevator apparatus to which the elevator rope according to the present invention is applied is not limited to the type in  FIG. 1 . The present invention can also be applied to machine-roomless elevators, elevator apparatuses that use two-to-one (2:1) roping methods, multi-car elevators, or double-deck elevators, for example. 
     Furthermore, the elevator rope according to the present invention can also be applied to ropes other than ropes for suspending a car  29 , such as compensating ropes or governor ropes, for example.