One of the objectives in elevator development work is to achieve an efficient and economical utilization of building space. In recent years, this development work has produced various elevator solutions without ma- chine room, among other things. Good examples of ele- vators without machine room are disclosed in specifi- cations EP 0 631 967 (A1) and EP 0 631 968. The eleva- tors described in these specifications are fairly ef- ficient in respect of space utilization as they have made it possible to eliminate the space required by the elevator machine room in the building without a need to enlarge the elevator shaft. In the elevators disclosed in these specifications, the machine is com- pact at least in one direction, but in other direc- tions it may have much larger dimensions than a con- ventional elevator machine.

In these basically good elevator solutions, the space required by the hoisting machine limits the freedom of choice in elevator lay-out solutions. Some space is needed to provide for the passage of the hoisting ropes. It is difficult to reduce the space required by the elevator car itself on its track and likewise the space required by the counterweight, at least at a reasonable cost and without impairing elevator per- formance and operational quality. In a traction sheave elevator without machine room, mounting the hoisting machine in the elevator shaft is difficult, especially in a solution with machine above, because the hoisting machine is a sizeable body of considerable weight. Es-

pecially in the case of larger loads, speeds and/or hoisting heights, the size and weight of the machine are a problem regarding installation, even so much so that the required machine size and weight have in practice limited the sphere of application of the con- cept of elevator without machine room or at least re- tarded the introduction of said concept in larger ele- vators.

Specification WO 99/43589 discloses an elevator sus- pended using flat belts in which relatively small di- version diameters on the traction sheave and diverting pulleys are achieved. However, the problem with this solution is the limitations regarding lay-out solu- tions, the disposition of components in the elevator shaft and the alignment of diverting pulleys. Also, the alignment of polyurethane-coated belts having a load-bearing steel component inside is problematic e. g. in a situation where the car is tilted. To avoid undesirable vibrations, an elevator so implemented needs to be rather robustly constructed at least as regards the machine and/or the structures supporting it. The massive construction of other parts of the elevator needed to maintain alignment between the traction sheave and diverting pulleys also increases the weight and cost of the elevator. In addition, in- stalling and adjusting such a system is a difficult task requiring great precision.

On the other hand, to achieve a small rope diversion diameter, rope structures have been used in which the load-bearing part is made of artificial fiber. Such a solution is exotic and the ropes thus achieved are lighter than steel wire ropes, but at least in the case of elevators designed for the commonest hoisting

heights, artificial-fiber ropes do not provide any substantial advantage, particularly because they are remarkably expensive as compared with steel wire ropes.

The object of the invention is to achieve at least one of the following aims. On the one hand, it is an aim the invention to develop the elevator without machine room further so as to allow more effective space utilization in the building and elevator shaft than before. This means that the elevator must be so con- structed that it can be installed in a fairly narrow elevator shaft if necessary. On the other hand, it is an aim of the invention to reduce the size and/or weight of the elevator or at least of the elevator ma- chine.

The object of the invention should be achieved without impairing the possibility of varying the basic eleva- tor layout.

The elevator of the invention is characterized by what is presented in the characterization part of claim 1.

Other embodiments of the invention are characterized by what is presented in the other claims.

By applying the invention, one or more of the follow- ing advantages, among others, can be achieved: - A small traction sheave makes it possible to achieve a compact elevator and elevator machine.

- By using a small coated traction sheave, the weight of the machine can easily be reduced even to about half or less of the weight of the machines now gen- erally used in elevators without machine room. For

example, in the case of elevators designed for a nominal load below 1000 kg, this means machines weighing 100-150 kg or even less. Via appropriate motor solutions and choices of materials, it is even possible to achieve machines weighing less than 100 kg.

- A good traction sheave grip and light-weight compo- nents allow the weight of the elevator car to be considerably reduced, and correspondingly the coun- terweight can also be made lighter than in current elevator solutions.

- A compact machine size and thin, substantially round ropes permit the elevator machine to be relatively freely placed in the shaft. Thus, the elevator solu- tion can be implemented in a fairly wide variety of ways in the case of both elevators with machine above and elevators with machine below.

- The elevator machine can be advantageously placed between the car and a shaft wall.

- All or at least part of the weight of the elevator car and counterweight can be carried by the elevator guide rails.

- In elevators applying the invention, an arrangement of centric suspension of the elevator car and coun- terweight can readily be achieved, thereby reducing the lateral supporting forces applied to the guide rails.

- Applying the invention allows effective utilization of the cross-sectional area of the shaft.

- The invention reduces the installation time and to- tal installation costs of the elevator.

- The elevator is economical to manufacture and in- stall because many of its components are smaller and lighter than those used before.

- The speed governor rope and the hoisting rope are usually different in respect of their properties and they can be easily distinguished from each other during installation if the speed governor rope is thicker than the hoisting ropes; on the other hand, the speed governor rope and the hoisting ropes may also be of identical structure, which will reduce ambiguities regarding these matters in elevator de- livery logistics and installation.

- The light, thin ropes are easy to handle, allowing considerably faster installation.

- E. g. in elevators for a nominal load below 1000 kg and a speed below 2 m/s, the thin and strong steel wire ropes of the invention have a diameter of the order of only 3-5 mm.

- With rope diameters of about 6 mm or 8 mm, fairly large and fast elevators according to the invention can be achieved.

- The traction sheave and the rope pulleys are small and light as compared with those used in conven- tional elevators.

- The small traction sheave allows the use of smaller operating brakes.

- The small traction sheave reduces the torque re- quirement, thus allowing the use of a smaller motor with smaller operating brakes.

- Because of the smaller traction sheave, a higher ro- tational speed is needed to achieve a given car speed, which means that the same motor output power can be reached by a smaller motor.

- Either coated or uncoated ropes can be used.

- It is possible to implement the traction sheave and the rope pulleys in such a way that, after the coat- ing on the pulley has been worn out, the rope will bite firmly on the pulley and thus a sufficient grip between rope and pulley in this emergency is main- tained.

- The use of a small traction sheave makes it possible to use a smaller elevator drive motor, which means reduced drive motor acquisition/manufacturing costs.

- The invention can be applied in gearless and geared elevator motor solutions.

- Although the invention is primarily intended for use in elevators without machine room, it can also be applied in elevators with machine room.

The primary area of application of the invention is elevators designed for transporting people and/or freight. The invention is primarily intended for use in elevators whose speed range, in the case of passen- ger elevators, is normally about or above 1.0 m/s but may also be e. g. only about 0.5 m/s. In the case of freight elevators, too, the speed is preferably about

0.5 m/s, though slower speeds can also be used with large loads.

In both passenger and freight elevators, many of the advantages achieved through the invention are pro- nouncedly brought out even in elevators for only 3-4 people, and distinctly already in elevators for 6-8 people (500-630 kg).

The elevator of the invention can be provided with elevator hoisting ropes twisted e. g. from round and strong wires. From round wires, the rope can be twisted in many ways using wires of different or equal thickness. In ropes applicable with the invention, the wire thickness is below 0.4 mm on an average. Well ap- plicable ropes made from strong wires are those in which the average wire thickness is below 0.3 mm or even below 0.2 mm. For instance, thin-wired and strong 4 mm ropes can be twisted relatively economically from wires such that the mean wire thickness in the fin- ished rope is in the range of 0.15... 0.23 mm, in which case the thinnest wires may have a thickness as small as only about 0.1 mm. Thin rope wires can easily be made very strong. The invention employs rope wires having a strength of about 2000 N/mm2 or more. A suit- able range of rope wire strength is 2300-2700 N/mm2.

In principle, it is possible to use rope wires as strong as about 3000 N/mm2 or even more.

In the following, the invention will be described in detail by the aid of a few examples of its embodiments with reference to the attached drawings, wherein Fig. 1 presents a diagram representing a traction sheave elevator according to the invention,

Fig. 2 presents a diagram representing another trac- tion sheave elevator according to the inven- tion, Fig. 3 presents a traction sheave applying the in- vention, Fig. 4 presents a coating solution according to the invention, Fig. 5a presents a steel wire rope used in the inven- tion, Fig. 5b presents another steel wire rope used in the invention, Fig. 5c presents a third steel wire rope used in the invention, and Fig. 6 presents a diagram illustrating a rope pulley lay-out according to the invention.

Fig. 1 is a diagrammatic representation of the struc- ture of an elevator. The elevator is preferably an elevator without machine room, in which the drive ma- chine 6 is placed in the elevator shaft. The elevator shown in the figure is a traction sheave elevator with machine above. The passage of the hoisting ropes 3 of the elevator is as follows: One end of the ropes is immovably fixed to an anchorage 13 located in the up- per part of the shaft above the path of a counter- weight 2 moving along counterweight guide rails 11.

From the anchorage, the ropes run downward and are passed around diverting pulleys 9 suspending the coun- terweight, which diverting pulleys 9 are rotatably mounted on the counterweight 2 and from which the ropes 3 run further upward to the traction sheave 7 of

the drive machine 6, passing around the traction sheave along rope grooves on the sheave. From the traction sheave 7, the ropes 3 run further downward to the elevator car 1 moving along car guide rails 10, passing under the car via diverting pulleys 4 used to suspend the elevator car on the ropes, and going then upward again from the elevator car to an anchorage 14 in the upper part of the elevator shaft, to which an- chorage the second end of the ropes 3 is fixed. An- chorage 13 in the upper part of the shaft, the trac- tion sheave 7 and the diverting pulley 9 suspending the counterweight on the ropes are preferably so dis- posed in relation to each other that both the rope portion going from the anchorage 13 to the counter- weight 2 and the rope portion going from the counter- weight 2 to the traction sheave 7 are substantially parallel to the path of the counterweight 2. Simi- larly, a solution is preferred in which 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 so disposed in relation to each other 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. With this arrangement, no additional diverting pul- leys are needed to define the passage of the ropes in the shaft. The rope suspension acts in a substantially centric manner on the elevator car 1, provided that the rope pulleys 4 supporting the elevator car are mounted substantially symmetrically relative to the vertical center line passing via the center of gravity of the elevator car 1.

The drive machine 6 placed in the elevator shaft is preferably of a flat construction, in other words, the machine has a small depth as compared with its width and/or height, or at least the machine is slim enough to be accommodated between the elevator car and a wall of the elevator shaft. The machine may also be placed differently, e. g. by disposing the slim machine partly or completely between an assumed extension of the ele- vator car and a shaft wall. The elevator shaft can be provided with equipment required for the supply of power to the motor driving the traction sheave 7 as well as equipment for elevator control, both of which can be placed in 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 a geared or gearless type. A prefer- able solution is a gearless machine comprising a per- manent magnet motor. The drive machine may be fixed to a wall of the elevator shaft, to the ceiling, to a guide rail or guide rails or to some other structure, such as a beam or frame. In the case of an elevator with machine below, a further possibility is to mount the machine on the bottom of the elevator shaft. Fig.

1 illustrates the economical 2: 1 suspension, but the invention can also be implemented in an elevator using a 1: 1 suspension ratio, in other words, in an elevator in which the hoisting ropes are connected directly to the counterweight and elevator car without diverting pulleys. Other suspension arrangements are also possi- ble in an implementation of the invention. The eleva- tor presented in the figure has automatic telescoping doors, but other types of automatic doors or turning doors can also be used in the elevator of the inven- tion.

Fig. 2 presents a diagram representing another trac- tion sheave elevator according to the invention. In this elevator, the ropes go upward from the machine.

This type of elevator is generally a traction sheave elevator with machine below. The elevator car 101 and the counterweight 102 are suspended on the hoisting ropes 103 of the elevator. The elevator drive machine 106 is mounted in the elevator shaft, preferably in the lower part of the shaft, and the hoisting ropes are passed via diverting pulleys 104,105 provided in the upper part of the elevator shaft to the car 101 and to the counterweight 102. The diverting pulleys 104,105 are placed in the upper part of the shaft and preferably separately mounted with bearings on the same axle so that they can rotate independently of each other. The hoisting ropes 103 consist of at least three parallel ropes.

The elevator car 101 and the counterweight 102 move in the elevator shaft along elevator and counterweight guide rails 110,111 guiding them.

In Fig. 2, the hoisting ropes run as follows: One end of the ropes is fixed to an anchorage 112 in the upper part of the shaft, from where it goes downward to the counterweight 102. The counterweight is suspended on the ropes 103 via a diverting pulley 109. From the counterweight, the ropes go further upward to a first diverting pulley 105 mounted on an elevator guide rail 110, and from the diverting pulley 105 further to the traction sheave 107 driven by the drive machine 106.

From the traction sheave, the ropes go again upward to a second diverting pulley 104, passing around it, af- ter which they pass via diverting pulleys 108 mounted on top of the elevator car and then go further to an

anchorage 113 in the upper part of the elevator shaft, where the other end of the hoisting ropes is fixed.

The elevator car is suspended on the hoisting ropes 103 by means of diverting pulleys 108. In the hoisting ropes 103, one or more of the rope portions between the diverting pulleys or between the diverting pulleys and the traction sheave may deviate from an exact ver- tical direction, a circumstance that makes it easy to provide a sufficient distance between different rope portions or a sufficient distance between the hoisting ropes and other elevator components. The traction sheave 107 and the hoisting machine 106 are preferably disposed somewhat aside from the path of the elevator car 101 as well as that of the counterweight 102, so they can easily be placed almost at any height in the elevator shaft below the diverting pulleys 104 and 105. If the machine is not placed directly above or below the counterweight or elevator car, this will al- low a saving in shaft height. In this case, the mini- mum height of the elevator shaft is exclusively deter- mined on the basis of the length of the paths of the counterweight and elevator car and the safety clear- ances needed above and below these. In addition, a smaller space at the top or bottom of the shaft will be sufficient due to the reduced rope pulley diameters as compared with earlier solutions, depending on how the rope pulleys are mounted on the elevator car and/or on the frame of the elevator car. Sometimes it may be advantageous to make all or some of the divert- ing pulleys larger than the traction sheave. Among these larger diverting pulleys may be especially those mounted in the upper part of the shaft. For example, in the case of 4: 1 suspension, a more spacious rope passage arrangement will be achieved by using somewhat

larger diverting pulleys in the upper part of the shaft. Of course, this also applies to elevators with machine above, not only to elevators with machine be- low.

Fig. 3 presents a partially sectioned view of a rope pulley 200 applying the invention. The rope grooves 201 on the rim 206 of the rope pulley are covered by a coating 202. Provided in the hub of the rope pulley is a space 203 for a bearing used to mount the rope pul- ley. The rope pulley is also provided with holes 205 for bolts, allowing the rope pulley to be fastened by its side to an anchorage in the hoisting machine 6, e. g. to a rotating flange, to form a traction sheave 7, in which case no bearing separate from the hoisting machine is needed. The coating material used on the traction sheave and the rope pulleys may consist of rubber, polyurethane or a corresponding elastic mate- rial increasing friction. The material of the traction sheave and/or rope pulleys may also be so chosen that, together with the hoisting rope used, it forms a mate- rial pair such that the hoisting rope will bite firmly on the pulley after the coating on the pulley has been worn out. This ensures a sufficient grip between the rope pulley 200 and the hoisting rope 3 in an emer- gency where the coating 202 has been worn out from the rope pulley 200. This feature allows the elevator to maintain its functionality and operational reliability in the situation referred to. The traction sheave and/or the rope pulleys can also be manufactured in such manner that only the rim 206 of the rope pulley 200 is made of a material forming a grip increasing material pair with the hoisting rope 3. The use of strong hoisting ropes that are considerably thinner than normally allows the traction sheave and the rope

pulleys to be designed to considerably smaller dimen- sions and sizes than when normal-sized ropes are used.

This also makes it possible to use a motor of a smaller size with a lower torque as the drive motor of the elevator, which leads to a reduction of the acqui- sition cost of the motor. For example, in an elevator according to the invention designed for a nominal load below 1000 kg, the traction sheave diameter is pref- erably 120-200 mm, but it may even be less than this.

The traction sheave diameter depends on the thickness of the hoisting ropes used. In the elevator of the in- vention, the use of a small traction sheave, e. g. in the case of elevators for a nominal load below 1000 kg, makes it possible to achieve a machine weight even as low as about one half of the weight of currently used machines, which means producing elevator machines weighing 100-150 kg or even less. In the invention, the machine is understood as comprising at least the traction sheave, the motor, the machine housing struc- tures and the brakes. The diameter of the traction sheave depends on the thickness of the hoisting ropes used. The diameter ratio conventionally used is D/d=40 or higher, where D = traction sheave diameter and d = hoisting rope thickness. At the expense of wear resis- tance of the ropes, this ratio could be somewhat re- duced. Alternatively, without compromising 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 stress for each rope is smaller. Such a D/d ratio be- low 40 could be e. g. a D/d ratio equal to about 30 or even less, e. g. D/d=25. However, reducing the D/d ra- tio considerably below 30 often radically reduces the service life of the rope, although this can be compen- sated for by using ropes of special construction. In

practice it is very difficult to achieve a D/d ratio below 20, but it might be accomplished by using a rope specifically designed for this purpose, although such a rope would most probably be expensive.

The weight of the elevator machine and its supporting elements used to hold the machine in place in the ele- vator shaft is at most about 1/5 of the nominal load.

If the machine is exclusively or almost exclusively supported by one or more elevator and/or counterweight guide rails, then the total weight of the machine and its supporting elements may be less than about 1/6 or even less than 1/8 of the nominal load. Nominal load of an elevator means a load defined for elevators of a given size. The supporting elements of the elevator machine may include e. g. a beam, carriage or suspen- sion bracket used to support or suspend the machine on/from a wall structure or ceiling of the elevator shaft or on the elevator or counterweight guide rails, or clamps used to hold the machine fastened to the sides of the elevator guide rails. It will be easy to achieve an elevator in which the machine deadweight without supporting elements is below 1/7 of the nomi- nal load or even about 1/10 of the nominal load or 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 machine weight in 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 combined weight of the machine and its supporting elements may be only 75 kg when the traction sheave diameter 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 ele- vator. As another example, using the same 2: 1 suspen- sion ratio, the same 160 mm traction sheave diameter and the same 4 mm hoisting rope diameter, in an eleva- tor for a nominal load of about 1000 kg, the total weight of the machine and its supporting elements is about 150 kg, so in this case the machine and its sup- porting elements have a total weight equaling about 1/6 of the nominal load. As a third example, let us consider an elevator designed for a nominal load of 1600 kg. In this case, when the suspension ratio is 2: 1, the traction sheave diameter 240 mm and the hoisting rope diameter 6 mm, the total weight of the machine and its supporting elements will be about 300 kg, i. e. about 1/7 of the nominal load. By varying the hoisting rope suspension arrangements, it is possible to reach a still lower total weight of the machine and its supporting elements. For example, when a 4: 1 sus- pension ratio, a 160 mm traction sheave diameter and a 4 mm hoisting rope diameter are used in an elevator designed for a nominal load of 500 kg, a total weight of machine and its supporting elements of about 50 kg will be achieved. In this case, the total weight of the machine and its supporting elements is as small as only about 1/10 of the nominal load. When the traction sheave size is substantially reduced and a higher sus- pension ratio introduced, the motor torque output re- quirement falls to a fraction of the level required in the starting situation. For example, if a 4: 1 suspen- sion ratio is used instead of 2: 1 suspension and if a traction sheave having a diameter of 160 mm is used instead of one with a diameter of 400 mm, then, if the increased losses are ignored, the torque requirement

falls to one fifth. Thus, the size of the machine is also really substantially reduced.

Fig. 4 presents a solution in which the rope groove 301 is in a coating 302 which is thinner at the sides of the rope groove than at the bottom. In such a solu- tion, the coating is placed in a basic groove 320 pro- vided in the rope pulley 300 so that deformations pro- duced in the coating by the pressure imposed on it by the rope will be small and mainly limited to the rope surface texture sinking into the coating. Such a solu- tion often means in practice that the rope pulley coating consists of rope groove-specific sub-coatings separate from each other, but considering manufactur- ing or other aspects it may be appropriate to design the rope pulley coating so that it extends continu- ously over a number of grooves.

By making the coating thinner at the sides of the groove than at its bottom, the strain imposed by the rope on the bottom of the rope groove while sinking into the groove is avoided or at least reduced. As the pressure cannot be discharged laterally but is di- rected by the combined effect of the shape of the ba- sic groove 320 and the thickness variation of the coating 302 to support the rope in the rope groove 301, lower maximum surface pressures acting on the rope and the coating are also achieved. One method of making a grooved coating 302 like this is to fill the round-bottomed basic groove 320 with coating material and then form a half-round rope groove 301 in this coating material in the basic groove. The shape of the rope grooves is well supported and the load-bearing surface layer under the rope provides a better resis- tance against lateral propagation of the compression

stress produced by the ropes. The lateral spreading or rather adjustment of the coating caused by the pres- sure is promoted by thickness and elasticity of the coating and reduced by hardness and eventual rein- forcements of the coating. The coating thickness on the bottom of the rope groove can be made large, even as large as half the rope thickness, in which case a hard and inelastic coating is needed. On the other hand, if a coating thickness corresponding to only about one tenth of the rope thickness is used, then the coating material may be clearly softer. An eleva- tor for eight persons could be implemented using a coating thickness at the bottom of the groove equal to about one fifth of the rope thickness if the ropes and the rope load are chosen appropriately. The coating thickness should equal at least 2-3 times the depth of the rope surface texture formed by the surface wires of the rope. Such a very thin coating, having a thick- ness even less than the thickness of the surface wire of the rope, will not necessarily endure the strain imposed on it. In practice, the coating must have a thickness larger than this minimum thickness because the coating will also have to receive rope surface variations rougher than the surface texture. Such a rougher area is formed e. g. where the level differ- ences between rope strands are larger than those be- tween wires. In practice, a suitable minimum coating thickness is about 1-3 times the surface wire thick- ness. In the case of the ropes normally used in eleva- tors, which have been designed for a contact with a metallic rope groove and which have a thickness of 8- 10 mm, this thickness definition leads to a coating at least about 1 mm thick. Since a coating on the trac- tion sheave, which causes more rope wear than the

other rope pulleys of the elevator, will reduce rope wear and therefore also the need to provide the rope with thick surface wires, the rope can be made smoother. Rope smoothness can naturally be improved by coating the rope with a material suited for this pur- pose, such as e. g. polyurethane or equivalent. The use of thin wires allows the rope itself to be made thin- ner, because thin steel wires can be manufactured from a stronger material than thicker wires. For instance, using 0.2 mm wires, 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 on other reasons, the wires in the steel wire rope may preferably have a thickness 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 individual wire has a sufficient wear resis- tance and a sufficiently low susceptibility to damage.

In the above, ropes made of 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. A traction sheave coating well suited for such a rope is already clearly below 1 mm thick. However, the coating should be thick enough to ensure that it will not be very easily scratched away or pierced e. g. by an occasional sand grain or similar particle having got between the rope groove and the hoisting rope. Thus, a desirable minimum coating thickness, even when thin-wire hoisting ropes are used, would be about 0.5... 1 mm. For hoisting ropes hav- ing small surface wires and an otherwise relatively smooth surface, a coating having a thickness of the form A+Bcosa is well suited. However, such a coating is also applicable to ropes whose surface strands meet the rope groove at a distance from each other, because if the coating material is sufficiently hard, each strand meeting the rope groove is in a way separately supported and the supporting force is the same and/or as desired. In the formula A+Bcosa, A and B are con- stants so that A+B is the coating thickness at the bottom of the rope groove 301 and the angle a is the angular distance from the bottom of the rope groove as measured from the center of curvature of the rope groove cross-section. Constant A is larger than or equal to zero, and constant B is always larger than zero. The thickness of the coating growing thinner to- wards the edges can also be defined in other ways be- sides using the formula A+Bcosa so that the elasticity decreases towards the edges of the rope groove. The elasticity in the central part of the rope groove can also be increased by making an undercut rope groove and/or by adding to the coating on the bottom of the

rope groove a portion of different material of special elasticity, where the elasticity has been increased, in addition to increasing the material thickness, by the use of a material that is softer than the rest of the coating.

Fig. 5a, 5b and 5c present cross-sections of steel wire ropes used in the invention. The ropes in these figures contain thin steel wires 403, a coating 402 on the steel wires and/or partly between the steel wires and in Fig. 5a a coating 401 over the steel wires. The rope presented in Fig. 5b is an uncoated steel wire rope with a rubber-like filler added to its interior structure, and Fig. 5a presents a steel wire rope pro- vided with a coating in addition to a filler added to the internal structure. The rope presented in Fig. 5c has a non-metallic core 404, which may be a solid or fibrous structure made of plastic, natural fiber or some other material suited for the purpose. A fibrous structure will be good if the rope is lubricated, in which case lubricant will accumulate in the fibrous core. The core thus acts as a kind of lubricant stor- age. The steel wire ropes of substantially round cross-section used in the elevator of the invention may be coated, uncoated and/or provided with a rubber- like filler, such as e. g. polyurethane or some other suitable filler, added to the interior structure of the rope and acting as a kind of lubricant lubricating the rope and also balancing the pressure between wires and strands. The use of a filler makes it possible to achieve a rope that needs no lubrication, so its sur- face can be dry. The coating used in the steel wire ropes may be made of the same or nearly the same mate- rial as the filler or of a material that is better suited for use as a coating and has properties, such

as friction and wear resistance properties, that are better suited to the purpose than a filler. The coat- ing of the steel wire rope may also be so implemented that the coating material penetrates partially into the rope or through the entire thickness of the rope, giving the rope the same properties as the filler men- tioned above. The use of thin and strong steel wire ropes according to the invention is possible because the steel wires used are wires of special strength, allowing the ropes to be made substantially thin as compared with steel wire ropes used before. The ropes presented in Fig. 5a and 5b are steel wire ropes hav- ing a diameter of about 4 mm. For example, when a 2: 1 suspension ratio is used, the thin and strong steel wire ropes of the invention preferably have a diameter of about 2.5-5 mm in elevators for a nominal load below 1000 kg, and preferably about 5-8 mm in eleva- tors for a nominal load above 1000 kg. In principle, it is possible to use ropes thinner than this, but in this case a large number of ropes will be needed.

Still, by increasing the suspension ratio, ropes thin- ner than those mentioned above can be used for corre- sponding loads, and at the same time a smaller and lighter elevator machine can be achieved.

Fig. 6 illustrates the manner in which a rope pulley 502 connected to a horizontal beam 504 comprised in the structure supporting the elevator car 501 is placed in relation to the beam 504, said rope pulley being used to support the elevator car and associated structures. The rope pulley 502 presented in the fig- ure may have a diameter equal to or less than the height of the beam 504 comprised in the structure. The beam 504 supporting the elevator car 501 may be lo- cated either below or above the elevator car. The rope

pulley 502 may be placed completely or partially in- side the beam 504, as shown in the figure. The hoist- ing ropes 503 of the elevator in the figure run as follows: The hoisting ropes 503 come to the coated rope pulley 502 connected to the beam 504 comprised in the structure supporting the elevator car 501, from which pulley the hoisting rope runs further, protected by the beam, e. g. in the hollow 506 inside the beam, under the elevator car and goes then further via a second rope pulley placed on the other side of the elevator car. The elevator car 501 rests on the beam 504 comprised in the structure, on vibration absorbers 505 placed between them. The beam 504 also acts as a rope guard for the hoisting rope 503. The beam 504 may be a C-, U-, I-, Z-section beam or a hollow beam or equivalent.

It is obvious to the person skilled in the art that different embodiments of the invention are not limited to the examples described above, but that they may be varied within the scope of the following claims. For instance, the number of times the hoisting ropes are passed between the upper part of the elevator shaft and the counterweight or elevator car is not a very decisive question as regards the basic advantages of the invention, although it is possible to achieve some additional advantages by using multiple rope passages.

In general, embodiments should be so implemented that the ropes go to the elevator car at most as many times as to the counterweight. It is also obvious that the hoisting ropes need not necessarily be passed under the car. In accordance with the examples described above, a skilled person can vary the embodiment of the invention as the traction sheaves and rope pulleys, instead of being coated metal pulleys, may also be un-

coated metal pulleys or uncoated pulleys made of some other material suited to the purpose.

It is further obvious to the person skilled in the art that the metallic traction sheaves and rope pulleys used in the invention, which are coated with a non- metallic material at least in the area of their grooves, may be implemented using a coating material consisting of e. g. rubber, polyurethane or some other material suited to the purpose.

It is also obvious to the person skilled in the art that the elevator car, the counterweight and the ma- chine unit may be laid out in the cross-section of the elevator shaft in a manner differing from the lay-out described in the examples. Such a different lay-out might be e. g. one in which the machine and the coun- terweight are located behind the car as seen from the shaft door and the ropes are passed under the car di- agonally relative to the bottom of the car. Passing the ropes under the car in a diagonal or otherwise oblique direction relative to the form of the bottom provides an advantage when the suspension of the car on the ropes is to be made symmetrical relative to the center of mass of the elevator in other types of sus- pension lay-out as well.

It is further obvious to the person skilled in the art that the equipment required for the supply of power to the motor and the equipment needed for elevator con- trol can be placed elsewhere than in connection with the machine unit, e. g. in a separate instrument panel.

It is likewise obvious to the skilled person that an elevator applying the invention may be equipped dif- ferently from the examples described above.

It is also obvious to the skilled person that, instead of using ropes with a filler as illustrated in Fig. 5a and 5b, the invention may be implemented using ropes without filler, which are either lubricated or unlu- bricated. In addition, it is also obvious to the per- son skilled in the art that the ropes may be twisted in many different ways.

As average of the wire thicknesses, a statistical aver- age or mean value-e. g. the geometrical or arithmeti- cal mean value-of the thicknesses of all wires of a hoisting rope is understood. For statistical average or mean value, the standard deviation, Gauss distribution, medium error square or deviation square method etc. could be used. Often wires of the same thickness are used in a rope, in which case the average thickness de- scribes the thickness of each wire of the rope. If wires of different thicknesses should be used, for the same reason the maximum wire thickness in the rope should preferably not exceed the factor 4, more pref- erably 3 or most preferably 2 of the average wire thickness.