HK1066519B - Elevator and traction sheave of an elevator - Google Patents

Description

Elevator and traction sheave of elevator

Technical Field

The invention relates to an elevator and an elevator traction sheave.

Background

The operation of conventional traction sheave elevators is based on a solution in which the steel ropes serving as hoisting ropes and simultaneously as suspension ropes are driven by means of a metal traction sheave, often cast iron, driven by a drive machine. The movement of the hoisting ropes causes movement of the counterweight and elevator car suspended by them. The driving force imparted to the hoisting ropes by the traction sheave and the braking force by means of the traction sheave during braking are transmitted by friction between the traction sheave and the ropes.

The coefficient of friction between the material of the metal traction sheave used and the hoisting ropes is conventionally insufficient in the normal conditions of elevator operation to maintain a proper grip between the traction sheave and the hoisting ropes. The friction and the forces transmitted by the ropes can be increased by shaping the rope grooves of the traction sheave or, for example, by arranging the rope grooves with a coating increasing the coefficient of friction. In elevators provided with coated traction sheaves it is possible that in exceptional cases, such as in the event of a fire, the coating on the surface of the traction sheave is damaged by being burned out and melted away, in which case the coefficient of friction between the traction sheave and the hoisting ropes becomes insufficient and the elevator motion cannot be controlled, and the loss of proper gripping force between the traction sheave and the hoisting ropes is a troublesome and dangerous situation in respect of elevator operation and safety. When the coating is damaged, the ability of the system to maintain the functionality of the elevator is affected, while at the same time the reliability of the elevator may change due to the reduced grip especially in situations with a great tendency of unbalance between elevator and counterweight. This situation occurs when the elevator is unloaded or heavily loaded.

A solution to the problem of reduced grip due to loss of coating is disclosed in specification US 4465161. The solution proposed here is to provide the traction sheave with teeth below the coating in order to achieve a better grip between the traction sheave and the rope after the coating has been damaged, a problem with such teeth implemented in the known art is that the hoisting ropes come into contact with the traction sheave when the coating disappears, which damages the hoisting ropes and their structure. Especially heavy load contact between the teeth and the hoisting ropes may damage the ropes and may even cause the ropes to be damaged. This is a definite security risk. The reliability of the elevator can also change due to damaged hoisting ropes, which can lead to dangerous situations especially in situations where the elevator is subjected to heavy loads, and the loss of coating in the traction sheave achieved by the prior-art methods also has the consequence that after the teeth have come into contact with the steel ropes, it is often necessary to replace both the traction sheave and the hoisting ropes, since both are damaged. This can result in a significant increase in cost.

Disclosure of Invention

The object of the invention is to achieve an elevator in which the grip of the traction sheave on the hoisting ropes is sufficient even in the troubled case of the coating of the traction sheave being lost or damaged. Another object of the invention is to eliminate or avoid the drawbacks of the prior-art solutions and to achieve a traction sheave that has a sufficient grip on the hoisting ropes even after the coating has been lost, but that is also durable and improves the resistance of the ropes against wear and damage. Another object of the invention is to disclose a new type of traction sheave that ensures a sufficient grip between the traction sheave and the hoisting ropes after the coating on the surface of the traction sheave has been lost. It is also an object of the invention to apply the engagement between the ropes and the traction sheave to diverting pulleys possibly comprised in the elevator system.

In order to achieve the above object, according to one aspect of the invention, an elevator is provided in which a rope set comprising hoisting ropes of substantially circular cross-section suspends a counterweight and an elevator car and has one or more rope pulleys provided with rope grooves, one of said rope pulleys being a traction sheave coated with a material increasing the coefficient of friction, said traction sheave being driven by a drive machine to move the hoisting rope set, characterized in that at least the traction sheave and the hoisting rope set together constitute a material counterpart allowing the hoisting ropes to bite into the traction sheave after the coating on the surface of the traction sheave has been lost.

Preferably, the coating of the rope pulleys is made of rubber, polyurethane or other elastic material.

Preferably, the hoisting ropes used are super-strong thin ropes having a diameter of less than 8 mm.

Preferably, the super-strong string has a diameter of 3-5 mm.

Preferably each hoisting rope comprises a load-bearing part twisted from steel wire.

Preferably, the elevator can be used safely even in exceptional situations where the coating on the traction sheave surface has been lost.

According to another aspect of the invention a traction sheave is provided having on its outer edge rope grooves for the hoisting ropes and a coating increasing the friction for the hoisting ropes, characterized in that the material used on the traction sheave below the coating at least on the outer edge of the traction sheave is a material that allows the hoisting ropes to bite into it.

Preferably the material of the traction sheave is selected from mild steel, aluminium, cast iron, brass, other metals or equivalent materials suitable for the purpose.

Preferably, the traction sheave has a groove shape at the bottom of the groove that makes the hoisting ropes bite into the groove more efficiently.

The groove provided in the rope groove below the coating into which the hoisting ropes are engaged more effectively may preferably be an undercut groove, a V-groove, a groove of another shape suited to the purpose or a number of parallel grooves.

Preferably the traction sheave further comprises an insert, such that the hoisting ropes bite into it, said insert being placed under the coating on the traction sheave, into which insert the hoisting ropes can bite, maintaining a bite between the traction sheave and the hoisting ropes sufficient to operate the elevator.

Preferably the traction sheave has a roughened area below the coating in the rope grooves on the outer edge of the traction sheave so that a sufficient grip between the hoisting ropes and the traction sheave can be maintained.

Preferably, the hoisting ropes are steel wire ropes.

In the elevator of the invention the traction sheave provided with a coating, or at least its outer edge, is made of a material such that the hoisting ropes will bite into it after the coating on the surface of the traction sheave has been lost, the traction sheave being made of a material that allows the ropes to bite effectively into the material of the traction sheave. Thus, the elevator will maintain the required gripping force even in exceptional cases where the traction sheave coating is lost or damaged, due to the hoisting ropes biting into the traction sheave material. The traction sheave and the hoisting ropes thus constitute mating materials, chosen so that a sufficient grip is also obtained in case the coating on the surface of the traction sheave has been lost. In such a counterpart material the hoisting ropes bite into the traction sheave, thus creating a grip between them that is needed for operating the elevator. The effect of protecting the hoisting ropes is achieved when the material used on the traction sheave is softer than the material used on the hoisting ropes, which material allows the hoisting ropes to bite into it. The hoisting ropes bite into the traction sheave material while retaining their properties, because it is very unlikely that the hoisting ropes themselves will be damaged. In this solution of the invention the hoisting ropes are made of thin hard wires that can bite into the material of the traction sheave, so that a sufficient grip is maintained therebetween. Since the wires of the hoisting ropes are made of a very hard material, especially in thin and extra-strong ropes, e.g. mild steel, aluminum, cast iron, brass or some other material suited to the purpose is used as the traction sheave material, a sufficient grip will be provided between the traction sheave surface after the coating on them has been lost. A sufficient grip between the traction sheave and the hoisting ropes can also be achieved by adding an insert below the coating of the traction sheave, into which insert the hoisting ropes will bite in the same way as it can bite into the traction sheave itself as described above. In this case it is not necessary that the traction sheave and the hoisting ropes constitute a counterpart in which the hoisting ropes bite into the material of the traction sheave; instead, the added inserts and the lift cords constitute the aforementioned mating materials. A sufficient grip between the traction sheave and the hoisting ropes in the event that the coating increasing the friction coefficient on the surface of the traction sheave has been lost can be achieved by providing a roughened area in the traction sheave material below the coating in the rope grooves, which area gives a sufficient grip when contacting the hoisting ropes. It is not the object that the elevator according to the invention should function optimally for a long time in the above-mentioned exceptional situations in which the coating on the traction sheave surface is lost or damaged, but the arrangement according to the invention will allow the elevator to perform the function safely for a desired period of time. This is a complete arrangement in an elevator to ensure that the elevator will work safely temporarily in the above-mentioned exceptional cases. The grip between the traction sheave and the hoisting ropes in the event that the coating of the traction sheave has been lost or damaged is a transient property, meaning that the elevator must be repaired as soon as possible after the coating has been damaged. The elevator or traction sheave of the invention may also be provided with a detector producing an indication that the coating of the traction sheave has been lost or damaged. The detector provides information about the damage of the coating of the traction rope groove.

By applying the invention, the following advantages can be obtained:

after the coating has been lost, a sufficient grip for operating the elevator is still maintained between the traction sheave and the hoisting ropes;

the probability of damage of the hoisting ropes associated with contact between the traction sheave and the hoisting ropes is considerably lower than the solutions implemented by the prior-art methods;

after coating loss the properties of the hoisting ropes are not impaired, which ensures that the functionality and reliability of the elevator are maintained even in exceptional situations;

the elevator is safe for the user and can perform functions even in exceptional situations where the coating of the rope pulleys, especially the traction sheave, has been lost;

after contact has occurred between the outer edge of the traction sheave and the hoisting ropes due to coating loss, often only the traction sheave needs to be replaced, without the need to replace the hoisting ropes, which means a significant cost saving;

since it is possible to use fine wires in the ropes and since the finer wires can be made stronger, the hoisting ropes can be correspondingly thinner, which again results in space saving and a less costly lay-out solution;

the required gripping force between the hoisting rope and the indexing sheave can be easily achieved;

the bottom of the rope grooves below the coating may also be provided with various groove shapes allowing a faster and stronger grip, making it possible to obtain a stronger grip between the traction sheave and the hoisting ropes;

a sufficient grip between the traction sheave and the hoisting ropes can also be achieved by providing a roughened area on the bottom of the traction sheave groove below the coating;

it is possible to make only the outer edge of the traction sheave of a material that allows the rope to bite effectively into it;

elevator operation is temporarily safe in case the traction sheave coating has been lost.

Drawings

The invention will be described in detail hereinafter with reference to the accompanying drawings, in which

Fig. 1 presents a diagrammatic view of an elevator according to the invention;

FIG. 2 is a rope pulley to which the present invention is applied;

fig. 3 and 4 are rope grooves of a traction sheave according to the invention.

Detailed Description

Fig. 1 presents a diagrammatic illustration of the structure of an elevator. The elevator is preferably an elevator without machine room and the drive machine 6 is placed in the elevator shaft, although the invention can also be applied in elevators with machine room. The hoisting ropes 3 of the elevator run as follows: one end of the rope set is immovably fixed to an anchorage 13 in the upper part of the shaft above the track of the counterweight 2 moving along the counterweight guide rails 11, from where the ropes go downwards to diverting pulleys 9 suspending the counterweight and rotatably connected to the counterweight 2, and from these diverting pulleys 9 the ropes 3 go further upwards to the traction sheave 7 of the drive machine 6, passing around the traction sheave along rope grooves provided on the sheave. From the traction sheave 7 the ropes go downwards to the elevator car 1 moving along guide rails 10 of the elevator car, passing under it via diverting pulleys 4 used to suspend the elevator car on the roping, and finally, from the elevator car upwards to an anchorage 14 in the upper part of the shaft, to which the second end of the roping 3 is fixedly secured. The anchorage 13 in the upper part of the shaft, the traction sheave 7 and the diverting pulley 9 suspending the counterweight on the ropes are preferably so disposed in relation to each other that both the rope portion going from the anchorage 13 to the counterweight and the rope portion going from the counterweight 2 to the traction sheave 7 are substantially parallel to the path of the counterweight 2. Also a preferred solution is one in which the anchorage 14 in the upper part of the shaft, the traction sheave 7 and the diverting pulleys 4 suspending the elevator car on the ropes are disposed relative to each other so that the rope portion going from the anchorage 14 to the elevator car 1 and the rope portion going from the elevator car 1 to the traction sheave 7 are substantially parallel to the path of the elevator car 1. In this arrangement no further diverting pulleys are needed to define the passage of the ropes in the shaft. The rope suspension acts on the elevator car in a substantially aligned manner provided that the rope pulleys 4 supporting the elevator car are mounted substantially symmetrically with respect to a vertical center line passing through the center of gravity of the elevator car 1.

The drive machine 6, which is preferably placed in the elevator shaft, has a flat construction, in other words a machine having a small thickness compared to its width and/or height, or at least a machine which is slim enough to be accommodated between the elevator car and a wall of the elevator shaft. The machine may be otherwise housed. Especially an elongated machine, can be mounted fairly easily above the elevator car. It is advantageous to arrange the equipment needed for supplying power to the motor driving the traction sheave 7 as well as the equipment for elevator control in the elevator shaft, both of which can be placed on a common instrument panel 8 or mounted separately from each other or integrated partly or wholly with the drive machine 6. The drive machine may be of the geared or gearless type. The best solution is a gearless machine comprising a permanent magnet motor. The drive machine may be fixed to the wall of the elevator shaft, the ceiling, a guide rail or guide rails, or to some other structure, such as a beam or frame. Another possibility is to mount the machine on the bottom of the elevator shaft in the case of an elevator with machine below. Fig. 1 presents a practical 2: 1 suspension, but the invention can also be implemented in elevators employing a 1: 1 suspension ratio, in other words in elevators in which the hoisting ropes are connected directly to the counterweight and to the elevator car without diverting pulleys, or in elevators implemented using some other suspension arrangement suitable for traction sheave elevators.

Fig. 2 is a partial cross-sectional view of a rope pulley applying the invention. The rope grooves 101 on the outer edge 106 of the rope pulley are coated with a coating 102. The rope pulley hub houses a space 103 for mounting the rope pulley bearings. The rope pulley is also provided with holes 105 for bolts allowing the pulley to be fastened by its side to an anchorage, such as a turning flange, of the hoisting machine 6 to constitute the traction sheave 7, in which case no bearing separate from the hoisting machine is needed. The material of the rope pulley used as a traction sheave is chosen such that it forms a counterpart material with the hoisting ropes used, so that the hoisting ropes 3 bite into the rope grooves 101 after the coating 102 has been lost. This ensures that the rope pulley 100 coating 102 has a sufficient grip between the rope pulley 100 and the hoisting ropes 3 in an emergency situation where it has been lost. This feature allows the elevator to maintain its functionality and operational reliability in the mentioned situations. The traction sheave can also be made in such a way that the outer edge 106 of the rope pulley 100 serving only as a traction sheave is made of a material that constitutes a material pair with the hoisting ropes 3 that increases the gripping force.

Figure 3 is a cross-sectional view of a rope groove illustrating a structural solution for improving the grip after the coating has been lost or worn away. The groove shape 203 in the groove below the coating 202 at the bottom of the rope groove 201 allows the rope to bite into the rope groove more effectively. After the coating 202 has disappeared, the groove shape 203 or a comparable groove shape makes the rope bite more firmly into the rope pulley, ensuring a sufficient grip between the hoisting rope 3 and the rope pulley 100 functioning as a traction sheave, while at the same time protecting the hoisting rope against damage in connection with contact. The groove shape that allows the cord to bite into the cord groove more effectively may be a root cut, a V-groove or the like. It may also consist of many different shapes of parallel grooves below the coating 202 at the bottom of the rope groove 201, ensuring that the hoisting ropes 3 will bite into the rope pulley 100 after the coating 202 has been stripped off and the gripping force has been weakened.

Fig. 4 presents a rope pulley 100 functioning as a traction sheave and having a coating 202 in rope grooves 201, in which inserts 204 made of different materials have been added under the coating to enhance the biting effect. In this solution, in case the coating 202 has been lost on the surface of the rope pulley 100, the hoisting ropes 3 will penetrate into the insert 204, maintaining a sufficient grip between the hoisting ropes 3 and the rope pulley 100. The use of inserts makes it unnecessary to form a counterpart material that enhances the biting effect between the material of the hoisting rope and the entire rope pulley 100; but instead only an insert constituting such a counterpart material needs to be added. The insert material used may be mild steel, cast iron, brass or some other metal, or equivalent material suitable for the purpose. The insert 204 added on the bottom of the rope groove 201 below the coating 202 may also be a tube or a half-tube, encircling the entire rope pulley 100 along the bottom of the rope groove 201.

At least the material of the rope pulley 100 functioning as a traction sheave constitutes a counterpart material together with the hoisting ropes 3 used, in which the ropes 3 can bite into the rope pulley 100. The temporary reduction of friction between the rope pulley 100 and the hoisting ropes 3 occurring before the ropes 3 start to bite into the rope pulley 100 after the loss of coating 102 can be eliminated by grooves 203 made in different shapes on the bottom of the rope groove 201. In this arrangement a faster and stronger grip between the rope pulley 100 and the hoisting rope 3 is achieved. The coating material 202 used on the rope groove 201 may be rubber, polyurethane, or some other elastic material. The use of a coating 202 makes it possible to achieve a high friction between the rope pulley 100 and the hoisting ropes 3 and to form a uniform support for the hoisting ropes 3, reducing the strain in the rope inner parts. In the troubling case that the coating 202 disappears from the surface of the rope pulley 100, the chosen counter material and the final auxiliary groove 203 at the bottom of the rope groove 201 can quickly and reliably provide a sufficient coefficient of friction between the hoisting rope 3 and the rope pulley 100. This makes it possible to obtain guarantees about elevator operation and safety in respect of elevator functionality in troublesome situations. Using a number of thin and stiff steel wires in the hoisting ropes 3, the rope pulley 100 may be made of mild steel, cast iron, aluminium, brass or some other metal, or a comparable material suitable for the purpose and having various properties that make it suitable as rope pulley 100 material and allow the hoisting ropes 3 to bite into it, thus creating a grip sufficient for elevator operation and an effect that protects the hoisting ropes from damage in case the coating material 202 has been lost on the surface of the rope pulley 100. A sufficient grip between the traction sheave 100 and the hoisting ropes 3 in exceptional situations where the coating 202 has been lost can also be achieved by forming a roughened area on the surface of the traction sheave material below the coating 202 at the bottom of the rope grooves 201, which roughened area creates friction between the hoisting ropes 3 and the rope pulley 100 sufficient for the operation of the elevator.

The invention has been described above by way of example with reference to the accompanying drawings, and different embodiments of the invention are possible within the scope of the inventive idea. It is obvious in the scope of the inventive idea that a sufficient grip between the ropes and the traction sheave is created with the exception that the coating of the counterpart material consisting of hoisting ropes together with the traction sheave has been lost in the rope sheave grooves.

Claims (16)

1. Elevator, in which the rope set (3) comprising hoisting ropes of substantially circular cross-section suspends the counterweight (2) and the elevator car (1) and has one or more rope pulleys provided with rope grooves, one of said rope pulleys being a traction sheave (7) coated with a material increasing the coefficient of friction, said traction sheave being driven by a drive machine to move the hoisting rope set (3), characterized in that at least the traction sheave (7) forms a counterpart material with the hoisting rope set (3), allowing the hoisting ropes (3) to bite into the traction sheave (7) after the coating (102) on the surface of the traction sheave (7) has been lost.

2. Elevator according to claim 1, characterized in that the coating of the rope pulleys is made of rubber, polyurethane or other elastic material.

3. Elevator according to claim 1, characterized in that the hoisting ropes (3) used are super-strong thin ropes having a diameter of less than 8 mm.

4. Elevator according to claim 2, characterized in that the hoisting ropes (3) used are super-strong thin ropes having a diameter of less than 8 mm.

5. Elevator according to claim 3, characterized in that the super-strong strings have a diameter of 3-5 mm.

6. Elevator according to claim 4, characterized in that the super-strong strings have a diameter of 3-5 mm.

7. Elevator according to any one of the preceding claims, characterized in that the hoisting ropes (3) comprise a load-bearing part twisted from steel wire.

8. Elevator according to any one of claims 1-6, characterized in that the elevator can be used safely even in exceptional situations where the coating (102) on the surface of the traction sheave (7) has been lost.

9. Elevator according to claim 7, characterized in that the elevator can be used safely even in exceptional situations in which the coating (102) on the surface of the traction sheave (7) has been lost.

10. Traction sheave (7) having on its outer edge (106) rope grooves (101) for the hoisting ropes (3) and a coating (102) increasing the friction to the hoisting ropes (3), characterized in that the material used on the traction sheave (7) at least below the coating (102) on the outer edge (106) of the traction sheave (7) is a material allowing the hoisting ropes (3) to bite into it.

11. Traction sheave (7) as defined in claim 10, characterized in that the material of the traction sheave (7) is selected from mild steel, aluminium, cast iron, brass, other metals or equivalent materials suitable for the purpose.

12. Traction sheave (7) according to claim 10 or 11, characterized by a groove shape (203) at the bottom of the rope groove (201) of the traction sheave (7) that makes the hoisting ropes (3) bite into the groove more effectively.

13. Traction sheave (7) as claimed in claim 12, characterized in that the groove (203) provided in the rope groove (201) below the coating (202) into which the hoisting ropes (3) bite more effectively can be an undercut groove, a V-groove, a groove of another shape suited to the purpose or a number of parallel grooves.

14. Traction sheave (7) according to claim 10 or 11, characterized in that it further comprises an insert (204) into which the hoisting ropes bite, said insert being placed under the coating (201) on the traction sheave (7) into which the hoisting ropes (13) can bite, maintaining a bite between the traction sheave (7) and the hoisting ropes (3) sufficient for operating the elevator.

15. Traction sheave (7) as defined in claim 10 or 11, characterized in that the traction sheave has a roughened area below the coating (102) in the rope grooves (201) on the outer edge (106) of the traction sheave (7) so that a sufficient grip between the hoisting ropes (3) and the traction sheave (7) can be maintained.

16. Traction sheave (7) according to claim 10, characterized in that the hoisting ropes are steel wire ropes.