ROPE FOR ELEVATOR

Abstract

 In an elevator rope, outer layer strands are twisted together on an outer circumference of an inner layer rope, and a resin outer layer coating body is coated on an outer circumference of the layer of outer layer strands. A fiber core that is made of synthetic resin is disposed centrally in the inner layer rope. A resin round bar core, or a resin twisted core, for example, is used as the fiber core. A plurality of inner layer strands are twisted together outside the fiber core. A resin inner layer coating body is coated on an outer circumference of the layer of inner layer strands. The inner layer strands and the outer layer strands are constituted by twisting together a plurality of steel wires.

Description

TECHNICAL FIELD

[0001] The present invention relates to an elevator rope that has a plurality of strands that are formed by twisting together a plurality of steel wires.

BACKGROUND ART

[0002] Conventional elevator ropes have: an inner layer rope; a resin inner layer coating body that coats an outer circumference of the inner layer rope; a plurality of outer layer strands that are twisted together on an outer circumference of the inner layer coating body; and a resin outer layer coating body that coats an outer circumference of the outer layer strand layer. The inner layer rope has: a core rope that includes a plurality of core strands; a core rope coating body that is coated onto an outer circumference of the core rope; and a plurality of inner layer strands that are twisted together on an outer circumference of the core rope coating body. The core strand, the inner layer strands, and the outer layer strands are each configured by twisting together a plurality of steel wires (see Patent Literature 1, for example).

CITATION LIST

PATENT LITERATURE

[0003] [Patent Literature 1]
Japanese Patent No. 4108607 (Gazette)

SUMMARY OF THE INVENTION

PROBLEM TO BE SOLVED BY THE INVENTION

[0004] In conventional elevator ropes such as that described above, a straight core strand is disposed centrally in the core rope. Because this straight core strand is not twisted together with other strands, it is less likely to be subjected to constraining forces from other strands. Because of that, due to manufacturing problems such as nonuniformity of wire tension during manufacturing, for example, there is concern that if strain is generated in a portion of the wire that constitutes the straight core strand, making the wire break early, or on the other hand, if loosening arises, making the wires become slack, broken or loose wire may protrude outside the elevator rope, making it necessary to replace the elevator rope early.

[0005] The present invention aims to solve the above problems and an object of the present invention is to provide an elevator rope that can extend service life by suppressing external wire protrusion.

MEANS FOR SOLVING THE PROBLEM

[0006] 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 a plurality of inner layer strands in which a plurality of steel wires are twisted together, and an outer circumference of which is coated by a resin outer layer coating body, wherein a fiber core that is made of synthetic fiber is disposed centrally in the inner layer rope.

EFFECTS OF THE INVENTION

[0007] In an elevator rope according to the present invention, because the fiber core that is made of synthetic fiber is disposed centrally in the inner layer rope, strands that are not twisted together with other strands are no longer disposed centrally in the inner layer rope, thereby enabling service life to be extended by enabling all of the strands to be subjected to constraining forces from other strands to suppress external wire protrusion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] 

Figure 1 is a cross section of an elevator rope according to Embodiment 1 of the present invention;

Figure 2 is a cross section of an elevator rope according to Embodiment 2 of the present invention;

Figure 3 is a cross section of an elevator rope according to Embodiment 3 of the present invention;

Figure 4 is a cross section of an elevator rope according to Embodiment 4 of the present invention;

Figure 5 is a cross section of an elevator rope according to Embodiment 5 of the present invention;

Figure 6 is a cross section of an elevator rope according to Embodiment 6 of the present invention; and

Figure 7 is a side elevation that shows an example of an elevator apparatus to which the elevator rope of Embodiments 1 through 6 is applied.

DESCRIPTION OF EMBODIMENTS

[0009] Preferred embodiments of the present invention will now be explained with reference to the drawings.

Embodiment 1

[0010] Figure 1 is a cross section of an elevator rope according to Embodiment 1 of the present invention. In the figure, a fiber core 1 is disposed centrally in an elevator rope. A synthetic fiber round bar core (a solid core) that is made of polypropylene or polyethylene, for example, is used as the fiber core 1.

[0011] A plurality of (in this case, eight) inner layer strands 2 are twisted together on an outer circumference of the fiber core 1. Each of the inner layer strands 2 is configured by twisting together a plurality of steel wires. In more detail, each of the inner layer strands 2 has: a core wire that is disposed centrally; a plurality of intermediate wires that are twisted together on an outer circumference of the core wire; and a plurality of outer layer wires that are twisted together on an outer circumference of the layer of intermediate wires. Diameters of the intermediate wires are less than diameters of the core wire and the outer layer wires.

[0012] An outer circumference of the layer of inner layer strands 2 is coated by a resin inner layer coating body 3. An inner layer rope 4 is constituted by the fiber core 1, the inner layer strands 2, and the inner layer coating body 3. The inner layer coating body 3 contacts the fiber core 1 between mutually-adjacent inner layer strands 2. The fiber core 1 and the inner layer coating body 3 are maintained in a state of being interposed between the mutually-adjacent inner layer strands 2 even when tension acts thereon during service.

[0013] A plurality of (in this case, nineteen) outer layer strands 5 are twisted together on an outer circumference of the fiber core 1. Diameters of the outer layer strands 5 are less than diameters of the inner layer strands 2. Each of the outer layer strands 5 is configured by twisting together a plurality of steel wires. In more detail, each of the outer layer strands 5 has: a core wire that is disposed centrally; and a plurality of outer layer wires that are twisted together on an outer circumference of the core wire. Diameters of the outer layer wires are identical to the diameter of the core wire.

[0014] An outer circumference of the layer of outer layer strands 5 is coated by a resin outer layer coating body 6. The outer layer strands 5 and the outer layer coating body 6 are glued using an adhesive. The outer layer coating body 6 contacts the inner layer coating body 3 between mutually-adjacent outer layer strands 5. The inner layer coating body 3 and the outer layer coating body 6 are maintained in a state of being interposed between the mutually-adjacent outer layer strands 5 even when tension acts thereon during service.

[0015] 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 coating body 3. The inner layer coating body 3 is constituted by a resin that is cross-linked by introducing a cross-linking agent. In addition, the coefficient of friction of the inner layer coating body 3 should be reasonably low in order to increase flexibility of the elevator rope and also to reduce loss that occurs during flexing by sheaves.

[0016] Thus, it is preferable for the material of the inner layer coating body 3 to be harder than a material of the outer layer coating body 6 and to have a lower coefficient of friction relative to identical metal materials. In addition, it is preferable for the inner layer coating body 3 to have superior wear resistance since slippage arises against the inner layer strands 2.

[0017] Since it is necessary to ensure traction capacity on the sheaves, the outer layer coating body 6 is constituted by a resin that has sufficient wear resistance at a coefficient of friction on the sheaves that is greater than or equal to 0.2, such as a polyurethane, for example. The outer layer strands 5 are constituted by a resin that is cross-linked by introducing a cross-linking agent.

[0018] In an elevator rope of this kind, because the fiber core 1 is disposed centrally, steel strands that are not twisted together with other strands do not exist. In other words, all of the strands 2 and 5 are twisted together with the other strands 2 and 5 without exception. Because of that, the likelihood that broken or loose wires will protrude outside the elevator rope due to frictional force between the wires and between the strands 2 and 5 is suppressed.

[0019] When a load acts on the elevator rope, the respective strands 2 and 5 share the load, and a rope cross section is deformed in a direction in which gaps between the respective strands 2 and 5 decrease, but the gaps between the strands 2 and 5 can be ensured, or contact pressure between the strands 2 and 5 can be reduced, by the central fiber core 1 holding the pressure that acts on the respective strands 2 and 5.

[0020] In addition, since the elevator rope according to Embodiment 1 has an inner layer rope 4 inside, strength is greater than that of ropes of identical diameter that have a fiber core at center and that have eight strands or six strands ("conventional ropes"). Because of that, it is conceivable that the load that acts on the elevator rope according to Embodiment 1 is greater than the loads that act on conventional ropes, and that the pressure that acts on the central fiber core 1 from the respective strands 2 and 5 is further increased.

[0021] In regard to this, if a twisted core of natural fiber (hemp, for example) that is generally used in conventional ropes were used as the fiber core 1, the fibers themselves would have cavities, and there would be gaps between the fibers, making reductions in diameter due to pressure from the strands 2 and 5 and overall collapse of rope shape more likely to occur. Coupled with age-related corrosion and deterioration, it is likely that become even more difficult to hold the pressure from the strands 2 and 5.

[0022] However, in Embodiment 1, because a synthetic fiber round bar core is used as the fiber core 1, the packing density of the fiber core 1 itself can be raised, enabling the occurrence of shape collapse to be suppressed in the face of greater loads.

[0023] In conventional ropes, contact pressure between the strands inside the ropes is reduced and frictional force is reduced by impregnating rope grease into the central fiber core. In contrast to that, in the elevator rope according to Embodiment 1, since the outer layer strands 5 are separated from sheave groove surfaces by the outer layer coating body 6, and the strands 2 and 5 are separated from each other by the outer layer coating body 6 and the inner layer coating body 3, and metal does not contact metal directly, abrasion of the strands 2 and 5 can be prevented, and flexural stresses that are generated inside the elevator rope can be reduced by a buffering action of the inner layer coating body 3 and the outer layer coating body 6.

[0024] Since the fiber core 1 is made of comparatively low-friction synthetic fiber, abrasion of the strands 2 and 5 can be reduced relative to movement of the respective strands 2 and 5 when the elevator rope tensile loads and bending loads act thereon. Consequently, it is not necessary to impregnate rope grease internally. Thus, there is no need to be concerned about effects of oil due to coating rupture during rope manufacturing, particularly during coating and molding.

[0025] In addition, because the number of outer layer strands 5 is greater than or equal to twice the number of inner layer strands 2, and is greater than or equal to sixteen, the pressure to which the outer layer strands 5 are subjected from sheave grooves can be reduced when the elevator rope is wound around the sheaves.

[0026] Furthermore, in order to generate traction on the sheaves, it is necessary to fix the outer layer coating body 6 to the outer layer strands 5 adhesively, and it is necessary to wash away extraneous contamination or oil satisfactorily during manufacturing of the outer layer strands 5 before fixing the outer layer coating body 6 to the outer layer strands 5 adhesively. Satisfactory washing in interior portions of the outer layer strands 5 is not possible if the construction of the outer layer strands 5 is complicated. In answer to that, because the outer layer strands 5 in Embodiment 1 have two-layer constructions in which a single layer of wires is bundled onto an outer circumference of a central wire, the construction is simple, sufficient strength is ensured, and the outer layer strands 5 are also sufficiently and easily washed, enabling the outer layer coating body 6 to be fixed firmly to the outer layer strands 5 adhesively.

[0027] Flexural stresses that are generated when passing through small-diameter sheaves can also be reduced compared to conventional ropes that have similar diameters by reducing wire diameters. The wires that constitute the outer layer strands 5 can also be reduced in diameter by increasing the number of outer layer strands 5.

[0028] In addition, because the inner layer strands 2 have a three-layer construction in which two layers of wires are bundled onto an outer circumference of a central wire, overall rope packing density is increased, and flexural stresses that are generated can be reduced. It is preferable for there to be six through eight inner layer strands 2. This is because if the number of inner layer strands 2 is less than six, the cross section of each of the inner layer strands 2 is increased, or gaps between the inner layer strands 2 increase, and if the number of inner layer strands 2 is greater than eight, on the other hand, it is necessary to increase the overall number of layers in the rope in order to raise the packing density.

[0029] One method for obtaining the effects of packing density improvements and bending stress reduction is to increase the overall number of layers in the rope further, but as the number of strands and the number of wires increase, the number of manufacturing steps increases, making this impractical in terms of manufacturing costs.

[0030]  In the case of the elevator rope according to Embodiment 1, not only does each of the outer layer strands 5 have a simple construction that is constituted by seven wires, but because the inner layer strands 2 also have a comparatively simple three-layer construction, the overall number of wires in the rope can be set to less than or equal to three hundred even though the number of strands is greater than or equal to twenty.

[0031] When conventional ropes are used, because sheave diameter D is set to greater than or equal to forty times rope diameter d, if the rope diameter is 12 mm, for example, the sheave diameter is set to greater than or equal to 480 mm. In the case of 8 x S (19), 12 mm in diameter (d), which is used most commonly, wire diameter δ of the outer layer strands is approximately 0.8 mm, and if a sheave of 480 mm (D) is used, then an index to evaluate generated flexural stresses D/δ = 600, and the ratio of wire diameter of the outer layer strands to rope diameter d/δ = 15.

[0032] In contrast to that, because the rope according to Embodiment 1 has the inner layer coating body 3 and the outer layer coating body 6, and the fiber core 1 is disposed centrally in the inner layer rope 4, metal does not contact metal directly. When metal does not contact directly in this manner, as also described in Patent Literature 1, even if used at D/d = 27, service life can be ensured that is equal to when D/d = 40 is used in a combination of conventional ropes and sheaves, and in that case D1/δ1 = 600 x 27/40 = 405.

[0033] From the above formula, δ1 = 240/405 = 0.59 mm, and by making the wire diameter of the outer layer strands relative to the rope diameter d1 such that d1/δ1 ≥ 12/0.59 = 20.3 ≈ 20.5, it becomes possible to reduce the sheaves by half (D/d = 20) compared to the minimum sheave diameter ϕ 480 that satisfies D/d ≥ 40 when using conventional ropes at a diameter of 12 mm.

[0034] Thus, by making the rope a multilayered lay, and increasing the number of outer layer strands 5, reductions in the constituent wire diameter are possible, and by satisfying the above conditions, it becomes possible to halve the diameter of the sheaves used and ensure equivalent service life, even if the rope diameter is identical to that of conventional ropes.

[0035] By making the diameters approximately equal in the outer layer wires (the wires on the outermost circumference), where stresses that are generated in the wires that constitute the respective strands 2 and 5 are most severe among the wires in the respective strands 2 and 5, generated flexural stresses can be made uniform in all portions. Thus, wire breakage is prevented from being generated early in specific portions, and the rope will not reach the end of its service life early due to collapse.

[0036] In order to achieve the above effects, the diameters of the outer layer wires should naturally be made equal, but when consideration is given to design tolerances of the rope, it is preferable in practice for diameter variations of the outer layer wires to be kept within 10 percent.

Embodiment 2

[0037] Next, Figure 2 is a cross section of an elevator rope according to Embodiment 2 of the present invention. In Embodiment 2, a synthetic fiber twisted core that is made of polypropylene or polyethylene, for example, is used as a fiber core 7. An outer circumference of the fiber core 7 is coated by a resin core coating body 8. A material that is similar or identical to that of an inner layer coating body 3 can be used as a material for the core coating body 8. An inner layer rope 4 according to Embodiment 2 is constituted by the fiber core 7, the core coating body 8, inner layer strands 2, and the inner layer coating body 3. The rest of the configuration is similar or identical to that of Embodiment 1.

[0038] In an elevator rope of this kind, because the core coating body 8 fills gaps in rope that constitutes the fiber core 7, filling factor is high, and age-related deterioration can be reduced, enabling similar effects to those in Embodiment 1, in which a round bar core is used as the fiber core 1, to be achieved.

Embodiment 3

[0039] Next, Figure 3 is a cross section of an elevator rope according to Embodiment 3 of the present invention. An inner layer rope 4 according to Embodiment 3 is constituted by a core rope 9, inner layer strands 2, and an inner layer coating body 3. The core rope 9 is constituted by: a fiber core 10; a plurality of (in this case, six) core strands 11 that are twisted together on an outer circumference of the fiber core 10; and a core rope coating body 12 that is coated onto an outer circumference of the layer of core strands 11. A synthetic fiber round bar core is used as the fiber core 10 in a similar manner to Embodiment 1. A material that is similar or identical to that of the inner layer coating body 3 can be used as a material for the core rope coating body 12.

[0040] Each of the core strands 11 is configured by twisting together a plurality of steel wires. In more detail, each of the outer layer strands 5 has: a core wire that is disposed centrally; and a plurality of outer layer wires that are twisted together on an outer circumference of the core wire. Diameters of the outer layer wires are identical to a diameter of the core wire. Diameters of the core strands 11 are less than diameters of the outer layer strands 5. Diameters of the wires in the core strands 11 are less than diameters of the wires in the outer layer strands 5. The rest of the configuration is similar or identical to that of Embodiment 1.

[0041] In an elevator rope of this kind, because the core rope 9 is disposed centrally, packing density of the steel wires in the entire rope is further improved, enabling the breaking strength to be improved.

Embodiment 4

[0042] Next, Figure 4 is a cross section of an elevator rope according to Embodiment 4 of the present invention. In Embodiment 4, a synthetic fiber twisted core is used as a fiber core 13 in a similar manner to Embodiment 2. An outer circumference of the fiber core 13 is coated by a resin core coating body 14. A material that is similar or identical to that of an inner layer coating body 3 can be used as a material for the core coating body 14.

[0043]  A core rope 9 according to Embodiment 4 is constituted by the fiber core 13, the core coating body 14, core strands 11, and a core rope coating body 12. The rest of the configuration is similar or identical to that of Embodiment 3.

[0044] In an elevator rope of this kind, because the core coating body 14 fills gaps in rope that constitutes the fiber core 13, filling factor is high, and age-related deterioration can be reduced, enabling similar effects to those in Embodiment 3, in which a round bar core is used as the fiber core 10, to be achieved.

Embodiment 5

[0045] Next, Figure 5 is a cross section of an elevator rope according to Embodiment 5 of the present invention. In the figure, a fiber core 15 that is constituted by a synthetic fiber twisted core is disposed centrally in a core rope 9 without modification (without using a core coating body). The rest of the configuration is similar or identical to that of Embodiment 4.

[0046] If an overall rope cross-sectional construction is a three-layer construction (a layer that includes the core strands 11, a layer that includes the inner layer strands 2, and a layer that includes the outer layer strands 5), then occupied area in a central portion is smaller than in a two-layer construction such as that of Embodiment 1 or 2. Because of that, in a three-layer construction, even if a fiber core 15 that is constituted by a twisted core is used without modification, gaps that form in each portion are reduced, enabling effects that are almost identical to those of Embodiment 4 to be achieved.

[0047] In Embodiment 5, the numbers of outer layer strands 5, inner layer strands 2, and core strands 11 are reduced sequentially (outer layer strands 5 > inner layer strands 2 > core strands 11). The numbers of outer layer strands 5 and inner layer strands 2 are also as explained in Embodiment 1, and steel wire packing density can be increased by further reducing the number of core strands 11 compared to the number of inner layer strands 2. Not only can the wire diameter thereby be reduced compared to conventional ropes, but the overall number of strands and number of wires in the rope can also be suppressed.

[0048] In addition, by making the outer layer wire diameter of the core strands 11 smaller than the diameter of the outer layer wires in the other strands 2 and 5, flexural stresses that arise in the core rope 9 during bending action can be reduced compared to other layers. Thus, the core rope 9 is prevented from being damaged before the other layers, enabling the occurrence of overall collapse of rope shape due to damage to the core rope 9 to be prevented.

Embodiment 6

[0049] Next, Figure 6 is a cross section of an elevator rope according to Embodiment 6 of the present invention. In Embodiments 3 through 5, six core strands 11 that have a two-layer construction were used, but in Embodiment 6, three core strands 11 are twisted together on an outer circumference of a fiber core 10. Each of the core strands 11 has a three-layer construction in which two layers of wires are bundled on an outer circumference of a central wire. The rest of the configuration is similar or identical to that of Embodiment 3.

[0050] According to an elevator rope of this kind, similar or identical effects to those of Embodiment 3 can be achieved while reducing the number of core strands 11.

[0051] Now, Figure 7 is a side elevation that shows an example of an elevator apparatus to which the elevator rope of Embodiments 1 through 6 is applied. 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 sheave 25 and a hoisting machine main body 26. The hoisting machine main body 26 has: a hoisting machine motor that rotates the sheave 25; and a hoisting machine brake that brakes the rotation of the sheave 25.

[0052]  A deflecting sheave 27 is mounted to the machine base 23. A plurality of elevator ropes 28 that function as a suspending means are wound around the sheave 25 and the deflecting sheave 27.

[0053] A car 29 is suspended on first end portions of the elevator ropes 28. Specifically, the car 29 is suspended inside the hoistway 21 by the elevator ropes 28 on a first side of the sheave 25. A counterweight 30 is suspended on second end portions of the elevator ropes 28. Specifically, the counterweight 30 is suspended by the elevator ropes 28 on a second side of the sheave 25.

[0054] 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 to the car 29.

[0055] Moreover, the type of elevator apparatus to which the elevator rope according to the present invention is applied is not limited to the type in Figure 7. For example, 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.
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.

Claims

1. An elevator rope comprising an inner layer rope that includes a plurality of inner layer strands in which a plurality of steel wires are twisted together, and an outer circumference of which is coated by a resin outer layer coating body,
the elevator rope being characterized in that:

a fiber core that is made of synthetic fiber is disposed centrally in the inner layer rope.

2. The elevator rope according to Claim 1, characterized in that the fiber core is a round bar core that is made of a resin.

3. The elevator rope according to Claim 1, characterized in that the fiber core is a twisted core that is made of a resin.

4. The elevator rope according to Claim 1, characterized in that an outer circumference of the fiber core is coated by a resin core coating body.

5. The elevator rope according to Claim 1, characterized in that all steel strands, including the inner layer strands, are twisted together with other strands.

6. The elevator rope according to Claim 1, characterized in that a total number of wires is less than or equal to three hundred.

7. The elevator rope according to Claim 1, characterized in further comprising a plurality of outer layer strands that are twisted together on an outer circumference of the inner layer rope,
the outer layer strands and the outer layer coating body being glued by an adhesive.

8. The elevator rope according to Claim 1, characterized in further comprising a plurality of outer layer strands that are twisted together on an outer circumference of the inner layer rope,
the number of the outer layer strands being greater than or equal to twice the number of the inner layer strands, and being greater than or equal to sixteen.

9. The elevator rope according to Claim 1, characterized in further comprising a plurality of outer layer strands that are twisted together on an outer circumference of the inner layer rope,
overall rope diameter being greater than or equal to 20.5 times an outer layer wire diameter of the inner layer strands and the outer layer strands, and
a difference between a maximum wire diameter and a minimum wire diameter of the outer layer wire diameter being within ten percent.

10. The elevator rope according to Claim 1, characterized in that:

a core rope is disposed centrally in the inner layer rope; and

the core rope comprises:

the fiber core that is disposed centrally;

a plurality of core strands that are twisted together outside the fiber core; and

a resin core rope coating body that is coated onto an outer circumference of a layer of the core strands.

11. The elevator rope according to Claim 10, characterized in further comprising a plurality of outer layer strands that are twisted together on an outer circumference of the inner layer rope,
the number of the outer layer strands, the inner layer strands, and the core strands being reduced sequentially.

12. The elevator rope according to Claim 10, characterized in further comprising a plurality of outer layer strands that are twisted together on an outer circumference of the inner layer rope,
an outer layer wire diameter of the core strands being less than an outer layer wire diameter of the inner layer strands and the outer layer strands.

Drawing