One of the goals in elevator development work has been to achieve an economical and efficient utilization of building space. In recent years, this development work has produced, among other things, various solutions for implementing an elevator without machine room.

Good examples of elevators without machine room are disclosed e. g. in specifications EP 0 631 967 and EP 0 631 968. The elevators described in these specifica- tions are fairly efficient in respect of space utili- zation, because they have made it possible to elimi- nate the space required in the building by the eleva- tor machine room, without a necessity of enlarging the elevator shaft. In the elevators disclosed in these specifications, the machine is compact at least in one direction, but in other directions it may be much lar- ger than a conventional elevator machine.

In these otherwise good elevator solutions, however, the space required by the hoisting machine constitutes a limitation on elevator lay-out options. The arrange- ments for the passage of the hoisting ropes take up space. The space required by the elevator car itself on its path of movement and likewise the space re- quired by the counterweight can hardly be reduced, at least at a reasonable cost and without compromising the performance and quality of service of the eleva- tor. In a traction sheave elevator without machine room, especially in the case of a solution with ma- chine above, installing the hoisting machine in the elevator shaft is difficult because the machine is

relatively heavy and large. The size and weight of es- pecially a machine designed for larger loads, higher speeds and/or greater hoisting heights are such a problem in respect of installation that in practice it has even limited the range of application of the con- cept of elevator without machine room or at least re- tarded the introduction of this concept in the case of larger elevators.

Specification WO 99/43589 discloses an elevator sus- pended on flat belts, which achieves relatively small belt bending diameters on the traction and deflecting sheaves. However, this solution involves the problems of a restricted lay-out solution, disposition of com- ponents in the elevator shaft and orientation of de- flecting pulleys. Furthermore, orientation of the polyurethane-coated belts having a load-bearing steel part inside is a problem e. g. in a situation where the car is tilted. An elevator implemented in this manner has to be fairly massive, at least as regards the ma- chine and/or the structures supporting it, in order to avoid undesirable vibrations. Also, the massiveness of the rest of the elevator structures required to main- tain the mutual orientation of the deflecting and traction sheaves increases the weight and costs of the elevator. In addition, the task of installing and ad- justing such a system is difficult and requires great precision.

Specification WO 01/68973 discloses an elevator pro- vided with coated hoisting ropes, in which the rope has been twisted from a number of coated strands and finally coated even externally with plastic or a simi- lar material. The external diameter of the rope is specified as 12 mm, which is a large diameter in com- parison with the present invention. A problem with this type of a fairly thick rope, which combines a

steel wire rope and a relatively thick and soft outer layer, is that, as the rope is running around the driving or deflecting pulleys, the steel core sinks towards the bottom of the rope groove, forcing the relatively thick and soft sheath to yield out of its way. The only yielding direction is upward along the edges of the rope groove, and consequently the sheath of the rope tends to be squeezed out of the rope groove. This results in fast rope wear.

Another expedient used to achieve a small bending di- ameter of the rope is to employ rope structures in which the load-bearing part is made of artificial fi- ber. An elevator rope of this type, based on an arti- ficial fiber structure, is disclosed in European pat- ent application no. EP1022376. Although a solution like this does make it possible to achieve ropes lighter than steel ropes, artificial fiber ropes do not provide any essential advantage, at least not in elevators for the commonest hoisting heights, espe- cially because artificial fiber ropes are considerably more expensive than steel ropes. In addition, the heat resistance of artificial fiber ropes e. g. in the case of fire is certainly not as good as the corresponding resistance of steel ropes.

The object of the present invention is to overcome the above-mentioned drawbacks and/or to reduce the size and/or weight of the elevator or at least its machin- ery by providing the possibility of using traction and deflecting sheaves of a smaller diameter. A concurrent objective is to achieve more efficient space utiliza- tion in the building.

The elevator of the invention provided with a coated hoisting rope is characterized by what is disclosed in the characterization part of claim 1. Other embodi-

ments of the invention are characterized by what is disclosed in the other claims.

The invention makes it possible to achieve one or more of the following advantages, among others: - the strong steel material employed allows the use of thin ropes - due to the thin and hard surface material, the mo- tion of the steel core towards the bottom of the rope groove is smaller, so the rope remains better in shape - the thin surface material layer also makes it possi- ble to achieve a rope with no large differences in the thickness of the filler material layer, which would make the rope non-homogeneous - the surface material layer makes it possible to achieve a good friction between the rope and the rope groove - as the elevator ropes are thin, the traction and rope sheaves are small and light as compared with those in conventional elevators - a small traction sheave allows the use of smaller operating brakes in the elevator - a small traction sheave involves a lower torque re- quirement, and consequently both the motor and its operating brakes can be smaller - the use of a smaller traction sheave requires a higher rotational speed for a given elevator car speed to be achieved, which means that the same mo- tor power output can be achieved by a smaller motor - the use of a small traction sheave allows a smaller elevator drive machine to be used, which means a re- duction in the acquisition/manufacturing costs of the drive machine - a good grip between the traction sheave and the rope and the use of light-weight components allow the

weight of the elevator car to be reduced considera- bly, and correspondingly a lighter counterweight can also be used than in present solutions a small machine size and thin, substantially round ropes allow a relatively free disposition of the elevator machine in the shaft. Thus, the elevator solution can be implemented in a variety of ways, both in the case of elevators with machine above and in the case of elevators with machine below the weight of the elevator car and counterweight can be completely or at least partially borne by the elevator guide rails in elevators applying the invention, centric suspen- sion of the elevator car and counterweight can be easily implemented, thus reducing lateral supporting forces applied to the guide rails by applying the invention, efficient utilization of the cross-sectional area of the shaft is achieved the invention shortens the time required for the in- stallation of the elevator and reduces the total in- stallation costs the light and thin ropes are easy to handle and fa- cilitate and accelerate the installation process considerably the thin and strong steel ropes of the invention have a diameter of the order of only 3-5 mm e. g. in the case of elevators designed for a nominal load below 1000 kg and speeds below 2 m/s using rope diameters of about 6 or 8 mm, fairly large elevators for relatively high speeds can be achieved by applying the invention, the invention can be applied in gearless and geared elevator motor solutions although the invention is primarily designed for use in elevators without machine room, it can be applied for use in elevators with machine room as well.

The primary area of application of the invention is elevators designed for the transportation of people or freight. Another primary area of application of the invention in passenger elevators whose speed range is conventionally about 1.0 m/s or higher but may also be e. g. only about 0.5 m/s. In the case of freight eleva- tors, too, the speed is preferably at least about 0.5 m/s, although with large loads even lower speeds may be used. In the elevator of the invention, elevator hoisting ropes twisted from substantially round and strong wires coated with e. g. polyurethane are used.

With round wires, the rope can be twisted in many ways using wires of different or equal thicknesses. In ropes applicable to the invention, the average wire thickness is below 0.4 mm. Well applicable ropes made from strong wires are ropes having an average wire thickness below 0.3 mm or even below 0.2 mm. For exam- ple, thin-wired strong 4-mm ropes can be twisted rela- tively economically from wires such that the average wire thickness in the finished rope is between 0.15...

0.25 mm, in which case the thinnest wires may even have a thickness of only about 0.1 mm. Thin rope wires can easily be made very strong. The invention uses rope wires having a strength over about 2000 N/mm2. A suitable range of rope wire strengths is 2300-2700 N/mm2. In principle, it is possible to use rope wires having a strength as high as about 3000 N/mm2 or even higher.

In the following, the invention will be described in detail by the aid of an embodiment example with refer- ence to the attached drawings, wherein Fig. 1 presents an oblique top view of a typical elevator solution according to the invention in which coated steel ropes are used,

Fig. 2 presents a cross-section of a prior-art coated steel rope, Fig. 3 presents a cross-section of a coated steel rope used in an elevator according to the in- vention, and Fig. 4 presents a longitudinal section of a part of a rope sheave used in the elevator of the in- vention.

Fig. 1 presents a typical elevator solution in which the hoisting rope 9 used is a coated steel rope. The elevator is preferably an elevator without machine room in which the hoisting machine 3 is connected via a traction sheave 5 to the hoisting ropes, which are coated hoisting ropes 9 of a substantially round cross-section, arranged side by side and supporting a counterweight 2 and an elevator car 1 moving on their paths, i. e. along guide rails 8 and 7. The hoisting ropes 9 placed side by side are fastened to a fixed starting point 10, from where the ropes go downwards towards a deflecting pulley 6 mounted in conjunction with the elevator car 1, substantially below the ele- vator car. From the deflecting pulley 6, the hoisting ropes go to a similar second deflecting pulley to the other lower edge of the elevator car and, having passed around this second deflecting pulley, the ropes go upwards to the traction sheave 5 of the elevator drive machine 3 mounted in the upper part of the ele- vator shaft. Having passed around the traction sheave 5 via its upper edge, the hoisting ropes go again down to the deflecting pulleys 6 connected to the counter- weight 2, pass around these pulleys by their lower edge and go up again to their fixed end point 11. The functions of the elevator are controlled by a control system 4.

Fig. 2 presents a prior-art elevator rope 13 coated with polyurethane 15 or equivalent. The thickness of the polyurethane layer 15 and the cross-sectional de- formation of the rope have been somewhat exaggerated for the sake of clarity. Due to the thickness of the polyurethane layer 15 or equivalent and its relatively soft mass, the force F acting on the elevator rope tends to press the steel core 14 of the rope towards the bottom of the rope groove of the rope sheave 12.

This pressure correspondingly tends to displace the filler, with the result that that filler moves upwards in the direction of the bottom surface of the rope groove as indicated by the arrows and tends to expand outside the rope groove. This large deformation pro- duces a hard strain on the rope and is therefore an undesirable situation.

Fig. 3 correspondingly presents the hoisting rope 9 of an elevator according to the invention. The core of the rope mainly consists of thin and strong steel wires 16 twisted in a suitable manner. The figure is not depicted in scale. The covering layer of the hoisting rope consists of a substantially thin sheath 17, which is softer than the core and is made of rub- ber, polyurethane or some other suitable non-metallic material having substantially hard properties and a high coefficient of friction. The hardness of the sheath is at least over 80 Shore A, preferably between 88-95 Shore A. The thickness of the sheath has been optimized with respect to durability, but it is still substantially small in relation to the diameter of the load-bearing core formed from steel wires 16. A suit- able diameter of the steel wire core is between 2-10 mm, and the ratio of the core diameter to the thick- ness of the sheath 17 is substantially greater than 4, preferably between 6-12 and suitably e. g. about 8. A suitable thickness of the steel wire core is about 4-6

mm, and in this case the sheath has a thickness sub- stantially between about 0.4-0. 6 mm, preferably e. g.

0.5 mm. The sheath should preferably have a thickness at least such that it will not be immediately worn away e. g. when a sand grain is caught between the hoisting rope 9 and the surface of the rope groove 18.

In practice, a suitable range of variation of the sheath thicknesses could be e. g. 0. 3-lmm, depending on the thickness of the core used.

The mutual structure of the sheath 17 and the core is so constructed that the friction between the sheath 17 and the core is greater than the friction between the sheath 17 and the rope groove 18 of the traction sheave 5. Thus, any undesirable sliding that eventu- ally may occur will occur at the desired place, i. e. between the traction sheave and the rope surface and not inside the hoisting rope between the core and the sheath, which could damage the hoisting rope 9.

Fig. 4 presents a sectional view of a part of a rope sheave 5 applying the invention. The rope grooves 18 have a semi-circular cross-sectional form. Because the hoisting ropes 9 use are considerably thinner and stronger than in a normal situation, the traction sheave and other rope sheaves can be designed to di- mensions considerably smaller than when ropes of a normal size are used. This also makes it possible to use an elevator drive motor of smaller size and lower torque, which leads to a reduction in the acquisition costs of the motor. For example, in an elevator ac- cording to the invention for a nominal load below 1000 kg, the traction sheave diameter is preferably 120-200 mm, but it may even be smaller than this. The diameter of the traction sheave depends on the thickness of the hoisting ropes used. Conventionally, a diameter ratio of D/d=40 is used, where D = diameter of traction

sheave and d = thickness of hoisting rope. At the ex- pense of wear resistance of the ropes, this ratio may be somewhat reduced. Alternatively, without compromis- ing on service life, the D/d ratio can be reduced if the number of ropes is increased at the same time, in which case the strain on each rope will be smaller.

Such a D/d ratio below 40 may be e. g. a D/d ratio of about 30 or even less, e. g. D/d=25. However, reducing the D/d ratio to a value considerably below 30 often impairs the service life of the rope, radically reduc- ing it, although this can be compensated by using ropes of special construction. Achieving a D/d ratio below 20 is very difficult in practice, but it might be achieved by using a rope specially designed for this purpose, although such a rope would most probably be expensive.

By virtue of the small traction sheave, in an elevator according to the invention for a nominal load e. g. be- low 1000 kg, a machine weight as low as about one half of the present machine weights can easily be achieved, which means elevator machines having a weight as low as below 100-150 kg. In the invention, the machine is regarded as comprising at least the traction sheave, the motor, the machine housing structures and the brakes.

It will be easy to achieve an elevator in which the machine without supporting elements has a dead weight below 1/7 of the nominal load or even about 1/10 of the nominal load or even still less. Basically, the ratio of machine weight to nominal load is given for a conventional elevator in which the counterweight has a weight substantially equal to the weight of an empty car plus half the nominal load. As an example of ma- chine weight in the case of an elevator of a given nominal weight when the fairly common 2: 1 suspension

ratio is used with a nominal load of 630 kg, the com- bined weight of the machine and its supporting ele- ments may be only 75 kg when the traction sheave di- ameter is 160 mm and hoisting ropes having a diameter of 4 mm are used, in other words, the total weight of the machine and its supporting elements is about 1/8 of the nominal load of the elevator. More generally, when a suspension ratio of 2: 1 is used, the thin and strong steel ropes of the invention have a diameter of 2.5-5 mm in elevators for a nominal load below 1000 kg and preferably about 5-8 mm in elevators for a nominal load over 1000 kg. In principle, it is possible to use ropes thinner than this, but in this case a large num- ber of ropes will be needed unless e. g. the suspension ratio is increased.

By using a polyurethane or similar coating, the smoothness of the rope is also improved. The use of thin wires allows the rope itself to be made thinner, because thin steel wires can be made stronger in mate- rial than thicker wires. For instance, using wires of about 0.2 mm, a 4 mm thick elevator hoisting rope of a fairly good construction can be produced. Depending on the thickness of the hoisting rope used and/or for other reasons, the wire thicknesses in the steel wire rope may preferably range between 0.15 mm and 0.5 mm, in which range there are readily available steel wires with good strength properties in which even an indi- vidual wire has a sufficient wear resistance and a sufficiently low susceptibility to damage.

In the above, ropes made from round steel wires have been discussed. Applying the same principles, the ropes can be wholly or partly twisted from non-round profiled wires. In this case, the cross-sectional ar- eas of the wires are preferably substantially the same as for round wires, i. e. in the range of 0.015 mm2 _

0.2 mm2. Using wires in this thickness range, it will be easy to produce steel wire ropes having a wire strength above about 2000 N/mm2 and a wire cross- section of 0.015 mm2-0. 2 mm2 and comprising a large cross-sectional area of steel material in relation to the cross-sectional area of the rope, as is achieved e. g. by using the Warrington construction. For the im- plementation of the invention, particularly well suited are ropes having a wire strength in the range of 2300 N/m2-2700 N/mm2, because such ropes have a very large bearing capacity in relation to rope thick- ness while the high hardness of the strong wires in- volves no substantial difficulties in the use of the rope in elevators.

The coating material selected for use in the steel ropes is a material that has good frictional proper- ties and a good wear resistance and is substantially hard as mentioned before. The coating of the steel ropes can also be so implemented that the coating ma- terial penetrates into the rope partially or through the entire rope thickness.

It is obvious to the person skilled in the art that the invention is not limited to the example described above, but that it may be varied within the scope of the claims presented below. In accordance with the ex- amples described above, the skilled person can vary the embodiment of the invention e. g. by using a suit- able coating in the rope grooves.

It is also obvious to the person skilled in the art that the ropes may be twisted in many different ways.

Likewise, the average of the wire thicknesses may be understood as referring to a statistical, geometrical or arithmetical mean value. To determine a statistical av- erage, it is possible to use e. g. the standard deviation or the Gauss distribution. It is further obvious that

the wire thicknesses in the rope may vary, e. g. even by a factor of 3 or more.

It is further obvious to the person skilled in the art that the ropes may be constructed in many different ways. The sheath may have e. g. a double-layer struc- ture comprising a somewhat softer outer layer of poly- urethane or equivalent that has good frictional prop- erties and a harder inner layer of polyurethane or equivalent.

It is also obvious to the skilled person that the lay- out of the elevator solution used may differ in may ways from that described above. Thus, the elevator drive machine 3 may be placed lower in the elevator shaft than in the above description, for instance so that the hoisting ropes 9 pass around the traction sheave 5 by its lower side. In this case, the deflect- ing pulleys may correspondingly be fixedly placed in the upper part of the elevator shaft.