Elevator device and repair method for same

Abstract

In an elevator device according to the present invention, a hoist machine is designed to raise and lower an elevator car via a plurality of old wire ropes, which had been wound around a drive sheave, before being replaced with a plurality of new wire ropes. The tensile strength of each new wire rope is greater than the tensile strength of each old wire rope. The difference between the unit mass of each new wire rope and the unit mass of each old wire rope, and the difference between the diameter of each new wire rope and the diameter of each old wire rope are each within a range that does not require replacement of the hoist machine in association with rope replacement.

Description

Elevator equipment and its repair method

[0001] The present disclosure relates to elevator systems and methods for retrofitting the same.

[0002] In a conventional elevator wire rope, a plurality of steel side strands are arranged around the core, and a plurality of steel auxiliary strands are arranged around the layer made up of the plurality of side strands (see, for example, Patent Document 1).

[0003] JP 2014-237908 A

[0004] In conventional elevator wire ropes such as those described above, multiple auxiliary strands are added to increase the strength and service life, resulting in a high steel wire filling rate and a high unit mass. Therefore, if an existing wire rope without auxiliary strands is replaced with a wire rope having auxiliary strands in order to improve its performance, it will also be necessary to replace peripheral equipment such as the hoist, making it difficult to improve the performance of the wire rope.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an elevator device and a method for repairing the same that can easily improve the performance of the wire rope.

[0006] The elevator device of the present disclosure has a plurality of new wire ropes, a car suspended in a hoistway by the plurality of new wire ropes, and a drive sheave around which the plurality of new wire ropes are wound, and is equipped with a hoist that raises and lowers the car via the plurality of new wire ropes, and the hoist is designed to raise and lower the car via a plurality of old wire ropes that are wire ropes that were wound around the drive sheave before being replaced with the plurality of new wire ropes, and the tensile strength of each new wire rope is higher than the tensile strength of each old wire rope, and the difference between the unit mass of each new wire rope and the unit mass of each old wire rope and the difference between the diameter of each new wire rope and the diameter of each old wire rope are each within a range that does not require replacement of the hoist when replacing the ropes. The elevator equipment renovation method of the present disclosure includes a rope replacement process in which multiple old wire ropes wound around the drive sheave of a hoist are replaced with multiple new wire ropes, and the tensile strength of each new wire rope is higher than the tensile strength of each old wire rope, and the difference between the unit mass of each new wire rope and the unit mass of each old wire rope, and the difference between the diameter of each new wire rope and the diameter of each old wire rope, are each within a range in which replacement of the hoist is not necessary due to rope replacement.

[0007] According to the present disclosure, the performance of wire ropes can be easily improved.

[0008] FIG. 1 is a schematic diagram showing an elevator apparatus according to embodiment 1. FIG. 2 is a cross-sectional view of the new wire rope of FIG. 1. FIG. 3 is a cross-sectional view of the old wire rope of embodiment 1. FIG. 4 is a cross-sectional view showing a first modified example of the new wire rope according to embodiment 1. FIG. 5 is a cross-sectional view showing a second modified example of the new wire rope according to embodiment 1. FIG. 6 is a cross-sectional view showing a third modified example of the new wire rope according to embodiment 1. FIG. 7 is a cross-sectional view showing a fourth modified example of the new wire rope according to embodiment 1. FIG. 8 is a cross-sectional view showing a fifth modified example of the new wire rope according to embodiment 1. FIG. 9 is a cross-sectional view showing a sixth modified example of the new wire rope according to embodiment 1.

[0009] Hereinafter, embodiments will be described with reference to the drawings. Embodiment 1. Figure 1 is a schematic diagram showing an elevator system according to embodiment 1. In Figure 1, a machine room 2 is provided above a hoistway 1. A hoisting machine 3 and a deflector sheave 6 are installed in the machine room 2.

[0010] The hoist 3 has a hoist motor 4, a hoist brake (not shown), and a drive sheave 5. The hoist motor 4 rotates the drive sheave 5. The hoist brake keeps the drive sheave 5 stationary. The hoist brake also brakes the rotation of the drive sheave 5.

[0011] A plurality of new wire ropes 7 are wound around the drive sheave 5 and the deflector sheave 6. In FIG. 1, only one new wire rope 7 is shown.

[0012] The car 8 and counterweight 9 are suspended within the hoistway 1 by a plurality of new wire ropes 7. The car 8 and counterweight 9 are raised and lowered within the hoistway 1 by rotating the drive sheave 5. That is, the hoisting machine 3 raises and lowers the car 8 and counterweight 9 via the plurality of new wire ropes 7.

[0013] A pair of car guide rails 10 and a pair of counterweight guide rails 11 are installed in the hoistway 1. In Fig. 1, only one car guide rail 10 and one counterweight guide rail 11 are shown.

[0014] A pair of car guide rails 10 guide the car 8 as it moves up and down. A pair of counterweight guide rails 11 guide the counterweight 9 as it moves up and down.

[0015] The car 8 has a car frame 12 and a car chamber 13. A plurality of new wire ropes 7 are connected to the car frame 12. The car chamber 13 is supported by the car frame 12.

[0016] Figure 2 is a cross-sectional view of the new wire rope 7 of Figure 1, showing a cross section perpendicular to the longitudinal direction of the old wire rope. The new wire rope 7 is an 8xS (21) type rope. The new wire rope 7 has a new rope core 31 and multiple new steel strands 32.

[0017] Although natural fibers may be used as the material for the new rope core 31, it is preferable to use long synthetic fibers. As the synthetic fiber, polyester multifilament fibers are particularly preferable in terms of mechanical properties and manufacturing costs.

[0018] The number of new strands 32 is eight. The multiple new strands 32 are arranged on the outer periphery of the new rope core 31. In addition, the multiple new strands 32 are twisted together on the outer periphery of the new rope core 31.

[0019] Each new strand 32 has a first central wire 33, a first outer layer 34, and a first inner layer 35. The first outer layer 34 is arranged on the outer periphery of the first central wire 33 via the first inner layer 35. The first outer layer 34 is also located on the outermost periphery of each new strand 32 and is in contact with the outer periphery of the new rope core 31. The first inner layer 35 is arranged between the first central wire 33 and the first outer layer 34.

[0020] The first outer layer 34 is made up of a plurality of first outer layer wires 36. The plurality of first outer layer wires 36 are twisted around the outer periphery of the first inner layer 35. The number of first outer layer wires 36 in each new strand 32 is preferably 10 to 15. In this example, the number of first outer layer wires 36 in each new strand 32 is 10.

[0021] The first inner layer 35 is made up of a plurality of first inner layer wires 37. The plurality of first inner layer wires 37 are twisted around the outer periphery of the first central wire 33. The number of first inner layer wires 37 in each new strand 32 is ten. The diameter of each first inner layer wire 37 is smaller than the diameter of each first outer layer wire 36. In this way, the cross-sectional configuration of each new strand 32 is sealed.

[0022] The elevator system renovation method of the first embodiment includes a rope replacement process. The rope replacement process is a process of replacing a plurality of old wire ropes wound around the drive sheave 5 with a plurality of new wire ropes 7. The plurality of old wire ropes are wire ropes that were wound around the drive sheave 5 before being replaced with the plurality of new wire ropes 7.

[0023] The hoist 3 is designed to raise and lower the car 8 and the counterweight 9 via a plurality of old wire ropes. In the first embodiment, the hoist 3 used before the rope replacement process is also used after the rope replacement process.

[0024] The drive sheave 5 is provided with a plurality of rope grooves into which the old wire ropes were inserted. Each new wire rope 7 is inserted into a corresponding one of the plurality of rope grooves.

[0025] 3 is a cross-sectional view of the old wire rope of the first embodiment, showing a cross section perpendicular to the longitudinal direction of the old wire rope. The old wire rope 20 is an 8xS(19) type rope conforming to JIS G 3525. In the EN region, it is designated as 8x19S.

[0026] The old wire rope 20 has an old rope core 21 and a plurality of old steel strands 22. The old rope core 21 is made of natural fiber.

[0027] The number of old strands 22 is eight. That is, the number of new strands 32 is the same as the number of old strands 22. The multiple old strands 22 are arranged on the outer periphery of the old rope core 21. In addition, the multiple old strands 22 are twisted together on the outer periphery of the old rope core 21.

[0028] Each old strand 22 has a second central wire 23, a second outer layer 24, and a second inner layer 25. The second outer layer 24 is arranged on the outer periphery of the second central wire 23 via the second inner layer 25. The second outer layer 24 is also located on the outermost periphery of each old strand 22 and is in contact with the outer periphery of the old rope core 21. The second inner layer 25 is arranged between the second central wire 23 and the second outer layer 24.

[0029] The second outer layer 24 is made up of a plurality of second outer layer wires 26. The plurality of second outer layer wires 26 are twisted together on the outer periphery of the second inner layer 25. The number of second outer layer wires 26 in each old strand 22 is nine.

[0030] The second inner layer 25 is made up of a plurality of second inner layer wires 27. The plurality of second inner layer wires 27 are twisted around the outer periphery of the second central wire 23. The number of second inner layer wires 27 in each old strand 22 is nine.

[0031] The tensile strength of each new wire rope 7 is higher than the tensile strength of each old wire rope 20. The difference between the unit mass of each new wire rope 7 and the unit mass of each old wire rope 20, and the difference between the diameter of each new wire rope 7 and the diameter of each old wire rope 20, are each within a range that does not require replacement of the hoist 3 when replacing the rope.

[0032] That is, the difference between the steel wire occupancy rate in each new wire rope 7 and the steel wire occupancy rate in each old wire rope 20 is within the tolerance range, and the difference between the unit mass of each new wire rope 7 and the unit mass of each old wire rope 20 is within the tolerance range. In addition, the difference between the diameter of each new wire rope 7 and the diameter of each old wire rope 20 is also within the tolerance range.

[0033] The difference between the unit mass of the new rope core 31 and the unit mass of the old rope core 21, and the difference between the tensile strength of each first outer layer wire 36 and the tensile strength of each second outer layer wire 26 are within the tolerance ranges. The tensile strength of each first outer layer wire 36 is 1770 N / m ２ For example, 1620 N / mm ２ Grade or 1770N / mm ２ It is a grade.

[0034] The tensile strength of the first central strand 33 is higher than that of the second central strand 23. The tensile strength of each of the first inner layer strands 37 is higher than that of each of the second inner layer strands 27.

[0035] The number of first outer layer wires 36 in each new strand 32 is greater than the number of second outer layer wires 26 in each old strand 22. The number of first inner layer wires 37 in each new strand 32 is greater than the number of second inner layer wires 27 in each old strand 22.

[0036] The tensile strength of the first central strand 33 and the tensile strength of each first inner layer strand 37 are approximately 1.5 times the tensile strength of the second central strand 23 and the tensile strength of each second inner layer strand 27. That is, the tensile strength of the first central strand 33 and the tensile strength of each first inner layer strand 37 are each 2000 N / m ２ or more, for example, 2300 N / mm ２ Grade or 2400N / mm ２ It is a grade.

[0037] The diameter of each first outer layer wire 36 is smaller than the diameter of each second outer layer wire 26. Furthermore, the cross-sectional occupancy rate of the multiple first outer layer wires 36 in each new strand 32 is lower than the cross-sectional occupancy rate of the multiple second outer layer wires 26 in each old strand 22.

[0038] Normally, if the difference in unit mass between the wire rope before and after replacement exceeds a certain level, the mass balance between the car and the counterweight changes. This makes it impossible to use the existing hoist motor and hoist brake. This can also result in traction loss.

[0039] For this reason, wire ropes with a different unit mass than conventionally used wire ropes are used for newly installed elevator systems. However, a significant proportion of the demand for wire ropes is for rope replacement during maintenance of existing elevator systems.

[0040] Another method for increasing rope strength without changing the unit mass is to use high-strength fibers for the rope core material, but high-strength fibers are usually expensive, making the entire wire rope expensive.

[0041] Another way to simply increase the strength of a wire rope is to upgrade its strength class by one level. However, if the tensile strength of each wire in the strand is increased to achieve a higher strength wire rope, the hardness of each wire also increases. This increases the contact pressure of the wire rope against the drive sheave, causing the problem of premature wear of the drive sheave.

[0042] In contrast, in the elevator apparatus and its renovation method of the first embodiment, the tensile strength of each new wire rope 7 is higher than the tensile strength of each old wire rope 20. Furthermore, the difference between the unit mass of each new wire rope 7 and the unit mass of each old wire rope 20 is within a range in which replacement of the hoist 3 is not required when replacing the rope. Furthermore, the difference between the diameter of each new wire rope 7 and the diameter of each old wire rope 20 is within a range in which replacement of the hoist 3 is not required when replacing the rope.

[0043] Therefore, compatibility between the old wire rope 20 and the new wire rope 7 can be ensured without replacing peripheral devices including the hoisting machine 3, and the performance of the wire rope that suspends the car 8 can be easily improved. This makes it possible to extend the maintenance and inspection cycle and replacement cycle of the new wire rope 7, thereby reducing the life cycle cost.

[0044] Furthermore, the new wire rope 7 can be used in both existing and new elevator systems, which allows for an increase in production volume of the new wire rope 7, improved production efficiency, and a reduction in the number of rope types.

[0045] Furthermore, since the new wire rope 7 is stronger than the old wire rope 20, it may be possible to reduce the number of new wire ropes 7 in a newly installed elevator compared to the number of old wire ropes 20. In this case, the number of rope grooves in the drive sheave of the new hoisting machine can be reduced, making it possible to reduce the thickness of the hoisting machine. It is also possible to reduce the thickness of the deflector sheave.

[0046] Furthermore, the hoist 3 used before the rope replacement process can be used after the rope replacement process, thereby facilitating repair work.

[0047] Furthermore, the tensile strength of the first central wire 33 is higher than the tensile strength of the second central wire 23. Furthermore, the number of first outer layer wires 36 in each new strand 32 is greater than the number of second outer layer wires 26 in each old strand 22. Furthermore, the difference between the unit mass of the new rope core 31 and the unit mass of the old rope core 21 is within the tolerance range. Furthermore, the difference between the tensile strength of each first outer layer wire 36 and each second outer layer wire 26 is within the tolerance range.

[0048] Therefore, the hardness of each of the first outer layer wires 36 in the new wire rope 7 that contacts the drive sheave 5 is the same as the hardness of each of the second outer layer wires 26. Therefore, compatibility with the old wire rope 20 is ensured while improving rope strength, and premature damage to the new wire rope 7 and premature wear of the drive sheave 5 can be suppressed.

[0049] Furthermore, the tensile strength of each of the first inner layer wires 37 is higher than the tensile strength of each of the second inner layer wires 27. Furthermore, the number of first inner layer wires 37 in each new strand 32 is greater than the number of second inner layer wires 27 in each old strand 22. This makes it possible to more reliably ensure compatibility with the old wire rope 20 while improving the rope strength.

[0050] The tensile strength of each of the first central wires 33 and each of the first inner layer wires 37 is 2000 N / m ２ As a result, the breaking load of the new wire rope 7 can be more reliably increased. Note that the upper limit of the tensile strength that can be achieved without increasing costs in steel wires used in elevator equipment is approximately 2500 N / mm ２ It is a grade.

[0051] The tensile strength of each of the first outer layer wires 36 is 1770 N / m ２ Therefore, damage to the new wire rope 7 and wear of the drive sheave 5 can be more reliably suppressed.

[0052] The number of new strands 32 is the same as the number of old strands 22. The number of first outer layer wires 36 in each new strand 32 is 10, which is more than the number of second outer layer wires 26 in each old strand 22. Therefore, compatibility with the old wire rope 20 is more reliably ensured, while the contact surface pressure of the new wire rope 7 against the drive sheave 5 is reduced, and damage to the new wire rope 7 and wear of the drive sheave 5 can be more reliably suppressed.

[0053] The new rope core 31 is made of long synthetic fibers, which allows the new wire rope 7 to have a longer life as a whole.

[0054] Furthermore, the cross-sectional configuration of each new strand 32 is a simple sealed shape. Therefore, the new wire rope 7 can be easily manufactured using the same manufacturing equipment as the old wire rope 20, and the manufacturing cost can be kept at the same level as the manufacturing cost of the old wire rope 20.

[0055] The diameter of wire ropes used in elevator systems is typically in the range of 8 mm to 12 mm. In such wire ropes, the greater the number of wires constituting the strand, the thinner the wires become. Furthermore, if the number of wires exceeds 30, limitations arise in the equipment for manufacturing the strand, increasing manufacturing costs. Therefore, it is preferable to limit the number of first outer layer wires 36 to 15 or less.

[0056] Furthermore, by making the number of new strands 32 six or more, the cross-sectional shape of the new wire rope 7 can be stabilized.

[0057] 4 is a cross-sectional view showing a first modified example of the new wire rope 7 according to embodiment 1. In the first modified example, the number of first outer layer wires 36 in each new strand 32 is 11. The number of first inner layer wires 37 in each new strand 32 is also 11. In other words, the new wire rope 7 of the first modified example is an 8xS(23) type rope.

[0058] 5 is a cross-sectional view showing a second modified example of the new wire rope 7 according to embodiment 1. In the second modified example, the number of first outer layer wires 36 in each new strand 32 is 12. The number of first inner layer wires 37 in each new strand 32 is also 12. In other words, the new wire rope 7 of the second modified example is an 8×S(25) type rope.

[0059] Figure 6 is a cross-sectional view showing a third modified example of the new wire rope 7 according to embodiment 1. In the third modified example, the number of first outer layer wires 36 in each new strand 32 is 13. The number of first inner layer wires 37 in each new strand 32 is also 13. In other words, the new wire rope 7 of the 36th modified example is an 8xS(27) type rope.

[0060] 7 is a cross-sectional view showing a fourth modified example of the new wire rope 7 according to embodiment 1. In the fourth modified example, the number of first outer layer wires 36 in each new strand 32 is 14. The number of first inner layer wires 37 in each new strand 32 is also 14. In other words, the new wire rope 7 of the fourth modified example is an 8xS(29) type rope.

[0061] Figure 8 is a cross-sectional view showing a fifth modified example of the new wire rope 7 according to embodiment 1. In the fifth modified example, the number of first outer layer wires 36 in each new strand 32 is 15. The number of first inner layer wires 37 in each new strand 32 is also 15. In other words, the new wire rope 7 of the fifth modified example is an 8xS(31) type rope.

[0062] 4 to 8 can also achieve the same effect as the new wire rope 7 in Fig. 2. In addition, the contact area between the new wire rope 7 and the drive sheave 5 increases, reducing the contact pressure. This allows the new wire rope 7 to have a longer life.

[0063] 9 is a cross-sectional view showing a sixth modified example of the new wire rope 7 according to embodiment 1. In the sixth modified example, each new strand 32 is composed only of a first central wire 33 and a first outer layer 34. The first outer layer 34 is in direct contact with the outer periphery of the first central wire 33 without the first inner layer 35 therebetween. In other words, the new strand 32 of the sixth modified example is a single lay type. The number of first outer layer wires 36 in each new strand 32 is 13.

[0064] The configuration shown in FIG. 9 can also provide the same effect as the new wire rope 7 shown in FIG.

[0065] Furthermore, the diameter of the first central wire 33 in the single lay type is larger than the diameter of the first central wire 33 in the sealed type. Therefore, the new wire rope 7 of the sixth modified example is suitable for application to elevator devices with small rope diameters.

[0066] The number of strands in each of the new wire rope 7 and the old wire rope 20 is not limited to eight.

[0067] Furthermore, the configuration of the new wire rope 7 can also be applied to wire ropes other than the wire rope that suspends the car 8, such as balancing ropes or governor ropes.

[0068] Furthermore, the layout of the entire elevator system is not limited to the layout shown in Fig. 1. For example, the roping system may be a 2:1 roping system.

[0069] The elevator system may also be a machine room-less elevator, a double-deck elevator, a one-shaft multi-car elevator system, etc. In the one-shaft multi-car system, an upper car and a lower car located directly below the upper car each independently ascend and descend in a common elevator shaft.

[0070] 3 Hoisting machine, 5 Drive sheave, 7 New wire rope, 8 Cage, 20 Old wire rope, 21 Old rope core, 22 Old strand, 23 Second central wire, 24 Second outer layer, 25 Second inner layer, 26 Second outer layer wire, 27 Second inner layer wire, 31 New rope core, 32 New strand, 33 First central wire, 34 First outer layer, 35 First inner layer, 36 First outer layer wire, 37 First inner layer wire.

Claims

1. An elevator apparatus having a plurality of new wire ropes, a cage suspended in a hoistway by the plurality of new wire ropes, and a drive sheave around which the plurality of new wire ropes are wound, the elevator apparatus comprising a hoisting machine configured to raise and lower the cage via the plurality of new wire ropes, the hoisting machine being designed to raise and lower the cage via a plurality of old wire ropes which were wound around the drive sheave before being replaced with the plurality of new wire ropes, the tensile strength of each of the new wire ropes being higher than the tensile strength of each of the old wire ropes, and the difference between the unit mass of each of the new wire ropes and the unit mass of each of the old wire ropes and the difference between the diameter of each of the new wire ropes and the diameter of each of the old wire ropes being within ranges such that replacement of the hoisting machine associated with the rope replacement is unnecessary.

2. Each of the new wire ropes has a new rope core and a plurality of steel new strands disposed on the outer periphery of the new rope core. Each of the new strands has a first central wire and a first outer layer composed of a plurality of first outer layer wires disposed on the outer periphery of the first central wire. Each of the old wire ropes has an old rope core and a plurality of steel old strands disposed on the outer periphery of the old rope core. Each of the old strands has a second central wire and a second outer layer composed of a plurality of second outer layer wires disposed on the outer periphery of the second central wire. The tensile strength of the first central wire is higher than the tensile strength of the second central wire. The number of the first outer layer wires in each of the new strands is larger than the number of the second outer layer wires in each of the old strands. The difference between the unit mass of the new rope core and the unit mass of the old rope core and the difference between the tensile strength of each of the first outer layer wires and the tensile strength of each of the second outer layer wires are within tolerances respectively. The elevator apparatus according to claim 1.

3. Each of the new strands is composed of a plurality of first inner layer strands, and further has a first inner layer disposed between the first central strand and the first outer layer. Each of the old strands further has a second central strand and a plurality of second inner layer strands, and a second inner layer disposed between the second central strand and the second outer layer. The tensile strength of each of the first inner layer strands is higher than that of each of the second inner layer strands, and the number of the first inner layer strands in each of the new strands is larger than the number of the second inner layer strands in each of the old strands. The elevator apparatus according to claim 2.

4. The tensile strength of the first central wire and the tensile strength of each of the first inner layer wires are each 2000 N / m ２ or more, and the elevator apparatus according to claim 3.

5. The tensile strength of each of the first outer layer strands is 1770 N / m ２ The elevator apparatus according to any one of claims 2 to 4, wherein the tensile strength is 1770 N / m or less.

6. The number of the new strands is the same as the number of the old strands, and the number of the first outer layer strands in each of the new strands is 10 or more and 15 or less. The elevator apparatus according to any one of claims 2 to 5.

7. The material of the new rope core is long fibers of synthetic fiber. The elevator apparatus according to any one of claims 2 to 6.

8. A rope replacement process for replacing a plurality of old wire ropes wound around a drive sheave of a hoist with a plurality of new wire ropes. The tensile strength of each of the new wire ropes is higher than that of each of the old wire ropes, and the difference between the unit mass of each of the new wire ropes and the unit mass of each of the old wire ropes, and the difference between the diameter of each of the new wire ropes and the diameter of each of the old wire ropes are each within a range where replacement of the hoist associated with the rope replacement is unnecessary. A method for modifying an elevator apparatus.

9. The hoist used before the rope replacement process is also used after the rope replacement process. The method for modifying an elevator apparatus according to claim 8.

10. The number of the new wire ropes is less than the number of the old wire ropes. The method for modifying an elevator apparatus according to claim 8 or claim 9.

11. Each of the new wire ropes has a new rope core and a plurality of steel new strands disposed on the outer periphery of the new rope core. Each of the new strands has a first central strand and a first outer layer composed of a plurality of first outer strands disposed on the outer periphery of the first central strand. Each of the old wire ropes has an old rope core and a plurality of steel old strands disposed on the outer periphery of the old rope core. Each of the old strands has a second central strand and a second outer layer composed of a plurality of second outer strands disposed on the outer periphery of the second central strand. The tensile strength of the first central strand is higher than the tensile strength of the second central strand. The number of the first outer strands in each of the new strands is larger than the number of the second outer strands in each of the old strands. The difference between the unit mass of the new rope core and the unit mass of the old rope core and the difference between the tensile strength of each of the first outer strands and the tensile strength of each of the second outer strands are each within the range of tolerance. The method for modifying an elevator device according to any one of claims 8 to 10.

12. Each of the new strands further has a first inner layer composed of a plurality of first inner strands disposed between the first central strand and the first outer layer. Each of the old strands further has a second central strand and a second inner layer composed of a plurality of second inner strands disposed between the second central strand and the second outer layer. The tensile strength of each of the first inner strands is higher than the tensile strength of each of the second inner strands. The number of the first inner strands in each of the new strands is larger than the number of the second inner strands in each of the old strands. The method for modifying an elevator device according to claim 11.

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