In most cases many elevators are needed in large and tall buildings for moving between floors and for transporting goods, the structures, and in particular the hoistways, of which elevators cause various problems. In such a case the design and implementation of an elevator arrangement for the building is challenging from the viewpoint of, inter alia, space usage, elevator traffic capacity and the smooth running of the elevator traffic. It would be advantageous in terms of space usage and costs if the same hoisting machine and the same power transmission means could be used for moving a number of different elevator cars and if different elevator cars could, if necessary, use the same elevator hoistways.

Known in the art are elevator arrangements in which a plurality of independently moving elevator cars are used in the same elevator hoistways. Such solutions are, for example, numerous elevator arrangements based on linear motor applications, wherein the fixed stator part of a linear motor is disposed in the elevator hoistway and the moving part on the elevator cars traveling in the elevator hoistway. Such solutions are disclosed, inter alia, in Chinese patent specification no. CN103303769 A and in US patent specification no. US2003000778 Al . One problem, among others, in these solutions is the transmission of a large amount of electric power to the moving elevator cars.

Also known in the art are other types of multicar elevator hoistway arrangements, in which each elevator car moving in the same elevator hoistway has its own hoisting machine, e.g. in a machine room above the elevator hoistway, and the hoisting ropes of the elevator cars are disposed to run from the elevator cars via the traction sheaves of the hoisting machines to the own counterweight of each elevator car. One such elevator hoistway arrangement is presented in US patent publication no. US2014367204 Al . A problem in this solution, as in other solutions of the same type, in addition to the transmission of electric power, is inter alia an extremely complex rope suspension arrangement with many counterweights. Likewise, the counterweights their tra ectories, and the hoisting rope bypasses of both the elevator cars and the counterweights, require a considerable amount of space. The aim of the present invention is to eliminate the aforementioned drawbacks and achieve an inexpensive and easy- to-implement elevator arrangement, in which e.g. only one main machine and one main power transmission means is used to move a plurality of different elevator cars in the same elevator hoistway. In this case one aim is also to achieve an elevator arrangement wherein the use of a number of elevator cars that are at least partly independently of each other in the same elevator hoistway with a small amount of electrical energy is enabled. Yet another aim is to achieve a coupling arrangement, by means of which an independent moving machine on the elevator car can easily be coupled to a main power transmission means, such as e.g. to a toothed belt functioning as a traction means, that is common to the elevator cars. The elevator arrangement according to the invention is characterized by what is disclosed in the characterization part of claim 1. Correspondingly, the coupling arrangement according to the invention is characterized by what is disclosed in the characterization part of claim 9. Other embodiments of the invention are characterized by what is disclosed in the other claims.

Some inventive embodiments are also discussed in the descriptive section of the present application. The inventive content of the application can also be defined differently than in the claims presented below. The inventive content may also consist of several separate inventions, especially if the invention is considered in the light of expressions or implicit sub-tasks or from the point of view of advantages or categories of advantages achieved. In this case, some of the attributes contained in the claims below may be superfluous from the point of view of separate inventive concepts. Likewise the different details presented in connection with each embodiment can also be applied in other embodiments. In addition it can be stated that at least some of the subordinate claims can, in at least some situations, be deemed to be inventive in their own right.

A preferred elevator system applying the invention has a plurality of independently moving elevator cars arranged on a track that essentially follows a traction means, e.g. a toothed belt, arranged into a loop, which traction means is driven with one or more hoisting machines supported in the elevator hoistway or otherwise in the building. The traction means transmits the moving force produced by the hoisting machine or hoisting machines to the elevator cars, where the moving force is distributed to become the driving force for the hoisting means on the elevator cars. Each elevator car has at least two hoisting means. One of the hoisting means of an elevator car is adapted to engage with a moving traction means. One hoisting means is adapted to engage with a static guide rail, e.g. with a toothed rack. The hoisting means are driven with a driving force obtained from the traction means, in which case the run speeds of the hoisting means are set in the power transmission apparatus in a controlled manner. Also set, in addition to the run speed, is the support force with which the hoisting means engages to the appropriate traction means or static guide rail.

The solution according to the invention enables a multicar elevator arrangement that is not only reliable but also saves energy, space and costs, and that preferably comprises elevator cars moving independently in the same elevator hoistway. The elevator arrangement according to the invention comprises one or more hoisting machines with traction sheaves as well as a traction means, such as e.g. a toothed belt, functioning as the main power transmission means and transmitting moving force from the traction sheave to the elevator cars. In the elevator arrangement according to the invention one and the same common traction means is adapted to transmit the moving force produced by one or more hoisting machines to all the elevator cars of the same elevator arrangement. A coupling arrangement is used in the elevator arrangement, in which coupling arrangement toothed racks and toothed belts are used as the means transmitting moving force to the elevator cars, and in which the toothings of the toothed belts are provided with magnets and ferromagnetic metallic elements. In this case the force of attraction of the magnets prevents the tooth forces from pushing the moving toothed belts apart from one another, or from pushing a moving toothed belt apart from a toothed rack, and consequently a reliable and strong transmission of moving force is achieved for moving the elevator car and for keeping it in its position.

One advantage, among others, of the solution according to the invention is that one and the same main hoisting machine and one and the same traction means functioning as the main power transmission means, and also if necessary the same elevator hoistways, can be used for moving a plurality of elevator cars independently, in which case valuable space in the building is saved and also the requirement for electrical energy can be reduced. Instead of supplying electrical energy directly for moving the elevator cars, such as in linear motor solutions, the independent moving of a number of elevator cars can be realized more advantageously with a mechanical moving machine. In this way the solution according to the invention offers a different underlying principle and a more advantageous solution than arrangements known in the art for the use of elevator cars moving independently in the same elevator hoistway.

In the following, invention will be described in more detail by the aid some examples of its embodiment with reference to the simplified and diagrammatic drawings attached, wherein

Fig. 1 presents a schematic side view of the basic principle of the power transmission of the elevator arrangement according to the invention,

Fig. 2 presents a schematic side view of the practical power transmission principle of the elevator arrangement according to the invention, Fig. 3 presents a simplified and diagrammatic side view of one elevator arrangement according to the invention ,

Fig. 4 presents a simplified and diagrammatic magnified side view of the elevator arrangement according to Fig. 3 at the top end and at the bottom end of the elevator hoistway,

Fig. 5 presents a simplified and diagrammatic side view of one independently-functioning power transmission apparatus for an elevator car, the apparatus being applicable for use in an elevator arrangement according to the invention,

Fig. 6 presents a simplified and diagrammatic side view of another independently-functioning power transmission apparatus for an elevator car, the apparatus being applicable for use in an elevator arrangement according to the invention,

Fig. 7 presents a side view of toothed belts, cross- sectioned in the longitudinal direction, for use in a coupling arrangement according to the invention, the belts being separated,

Fig. 8 presents a side view of the toothed belts according to Fig. 7, cross-sectioned in the longitudinal direction, when attached to each other, and

Fig. 9 presents a side view of a toothed rack and a toothed belt, cross-sectioned in the longitudinal direction, for use in a coupling arrangement according to the invention, when attached to each other . Figs. 1 and 2 illustrate the theory on which the idea of the invention is based. Fig. 1 presents a schematic view of the basic principle of the power transmission of the elevator arrangement according to the invention. In the solution according to Fig. 1 a gear wheel 7d functioning as a power transmission means is disposed between a toothed rack or toothed belt 4 moving in its longitudinal direction and a toothed rack 5 that is static in its longitudinal direction. The speed of movement of the toothed belt 4 upwards is v _b =l and the speed of movement of the static toothed rack 5 is v _r =0. Acting on the gear wheel 7d, therefore, is a speed of movement v _b =l from the toothed belt 4 side and a speed of movement v _r =0 from the toothed rack 5 side. When drawing the speeds as vectors in the same diagram, it is evident that the speed Vi=0.5 upwards of the center of the gear wheel 7d is one-half of the speed of movement v _b =l of the toothed belt 4.

Correspondingly Fig. 2 presents a schematic view of the power transmission principle of the elevator arrangement according to the invention in practice. In the solution according to Fig. 2 the single gear wheel has been replaced with a power transmission means 7e having two gear wheels 10 similar to each other, between which is made a suitable mechanical transmission, e.g. a V-belt transmission 11 with belt pulleys and V-belt. With the transmission and structure according to Fig. 2, it can be seen that when the upward speed of the toothed belt 4 is v _b =l, the upward speed of the whole power transmission means 7e is v _b =l/3*v _b .

Fig. 3 presents one type of elevator arrangement according to the invention. In the embodiment presented in Fig. 3 the elevator arrangement comprises at least two parallel elevator hoistways la and lb with elevator cars 6 and a storage channel lc for servicing and repairing the elevator cars 6 as well as for storing the elevator cars 6 not needed in the run cycle between traffic peaks. The storage channel lc is preferably in connection with the lowermost floor level 9, but it can also be some other floor level.

A traction means 4, such as a toothed belt, functioning as the main power transmission means is fitted to circulate around the elevator hoistways la and lb. Additionally, disposed in the top and bottom corners of the elevator hoistways la, lb are diverting pulleys 3a and 3b, around which the toothed belt 4 is arranged to pass. In addition, the elevator arrangement comprises a hoisting machine 2 with traction sheave 2a, the hoisting machine being fitted e.g. in one bottom corner instead of a diverting pulley. The hoisting machine 2 functions as the main hoisting machine of the elevator arrangement and is arranged to move the toothed belt 4 by means of the traction sheave 2a and the diverting pulleys 3a, 3b. Alternatively the arrangement can, if necessary, comprise more than one hoisting machine 2. In this case there can be e.g. either two, three or four hoisting machines 2 with traction sheaves 2a, in which case e.g. in the lattermost option all the diverting pulleys 3a, 3b would be replaced with a hoisting machine 2 and traction sheave 2a. When there is more than one hoisting machine 2, the hoisting machines 2 can be smaller and the load is distributed to all the hoisting machines 2 evenly.

The toothed belt 4 functioning as a traction means is adapted to form a closed loop having two longer vertical sections and two shorter sections remaining between them and connecting them. The directions and routes of the connecting sections are not of critical importance, but preferably the connecting sections are essentially horizontal. In this way the closed belt loop, when viewed from the side, forms a rectangle having a height longer than the width and having rounded corners.

The first vertical section of the toothed belt 4 travels upwards beside the outer wall of the first elevator hoistway la, turns by means of the diverting pulley 3a in the top corner of the hoistway la into the horizontal direction to travel towards the second elevator hoistway lb and after passing around the diverting pulley 3a in the top corner of the second hoistway lb turns back into the vertical direction to become the second vertical section, which travels downwards towards the diverting pulley 3b in the bottom corner of the second hoistway lb, after passing around the bottom of which diverting pulley 3b the toothed belt 4 travels again in an essentially horizontal direction to the traction sheave 2a of the main hoisting machine 2 in the bottom corner of the first hoistway la, and after passing around the bottom of which traction sheave 2a unites with its first vertical section to form a closed toothed belt loop.

The elevator arrangement additionally comprises a first essentially vertical toothed rack 5, static in the vertical direction, for the upward movement of the elevator car 6 and a second essentially vertical toothed rack 5, static in the vertical direction, for the downward movement of the elevator car 6. Preferably the toothed racks 5 are fastened to the inner walls of the elevator hoistways la and lb, one toothed rack per hoistway, but if the hoistways la and lb are joined into one hoistway the toothed racks 5 are in the same hoistway. The toothed racks 5 are arranged to be static in such a way that they do not move in the vertical direction. Instead, depending on the structural solutions, at the top end of the static toothed racks 5 on the uppermost floor level 8 and, correspondingly, at the bottom end of the static toothed racks 5 on the lowermost floor level 9 can be a separate toothed rack section, which can be moved in the lateral direction from the first elevator hoistway la to the second elevator hoistway lb and vice versa when transferring elevator cars 6 at the ends of the elevator hoistways from the first elevator hoistway la to the second elevator hoistway lb and vice versa. The transfer of elevator cars 6 from one elevator hoistway to another is not presented in more detail in this context.

One or more elevator cars 6 are fitted into the elevator hoistway la between the upward moving toothed belt 4 and the static toothed rack 5 and likewise one or more elevator cars 6 are fitted into the elevator hoistway lb between the downward moving toothed belt 4 and the static toothed rack 5. To the top part of each elevator car 6 is fastened a power transmission apparatus 7, which is arranged to function at least partly independently, regardless of the power transmission apparatuses 7 of the other elevator cars 6, said power transmission apparatus being a means supporting the elevator car 6 and transmitting at least moving force to it. Fig. 4 presents a simplified and diagrammatic magnified side view of the elevator arrangement according to Fig. 3 at the top end and at the bottom end of the elevator hoistways la and lb. The power transmission apparatus 7 supporting and moving an elevator car 6 preferably comprises e.g. two hoisting means 7a, 7b and the moving machine 7c driving them. The first hoisting means 7a is fitted to the edge of the power transmission apparatus 7, said edge being on the side of the outer wall of the elevator hoistway, to engage with the moving toothed belt 4 and the second hoisting means 7b is fitted to the edge of the power transmission apparatus 7, said edge being on the side of the inner wall of the elevator hoistway, to engage with the static toothed rack 5. The moving machine 7c of the power transmission apparatus 7 is arranged to adjust the forces and torques exerted on the hoisting means 7a and 7b and therefore simultaneously whether the power transmission apparatus 7, and the elevator car 6 coupled to it, is able to stay in its position in the vertical direction or whether it moves and, if it moves, at what speed and in which direction. The elevator arrangement according to the invention presented in Figs. 3 and 4 enables the use of a number of elevator cars 6 independently of each other, or at least almost independently of each other, in the same elevator hoistway la, lb in such a way that all the elevator cars 6 can be driven independently of each other by means of only one main hoisting machine 2 and one traction means 4. The traction means 4 is arranged to move along its trajectory all the time at a constant speed, moved by the main hoisting machine 2. In this case the traction means 4 functions all the time just like a main shaft rotating at constant speed all the time and the elevator cars 6 engage with the traction means 4 in such a way that they can stay, if necessary, in their position or move at the desired speed along with the constant motion of the traction means 4. If there are no calls the control system of the elevator drives the main hoisting machine 2 more slowly and even stops it for a while.

In the elevator arrangement according to the invention the elevator cars 6 travel in parallel elevator hoistways la and lb at least partly independently of each other by means of the moving force transmitted by the own power transmission apparatus 7 of each elevator car 6. Since the direction of movement of the common traction means, i.e. the moving toothed belt 4, of the elevator arrangement is upwards in the first elevator hoistway la and downwards in the second elevator hoistway lb, all the elevator cars 6 can therefore be driven with one main hoisting machine 2. The elevator cars 6 running downwards function in this case as counterweights for the elevator cars running upwards. As already described above, each elevator car 6 has its own power transmission apparatus 7, in which is e.g. variator machinery functioning as a moving machine 7c, by means of which the elevator car 6 can start moving from a floor level and accelerate to the speed of the moving toothed belt 4 and when arriving at a floor decelerate its speed again to zero.

There are e.g. two or more elevator cars 6 in one elevator system, depending on the height of the building. There can therefore be e.g. four, six, eight, ten or even more elevator cars, instead of two, preferably however an even number so that the elevator cars 6 function well as counterweights to each other .

The elevator arrangement can also have smart transfer means and a suitable transfer mechanism, with which some of the elevator cars 6 are arranged to be transferred out of the run cycle during a period between traffic peaks. The transfer mechanism can be at the top end or bottom end of the elevator hoistways la, lb or on a suitable intermediate floor. With the same transfer mechanism the elevator cars 6 can also be transferred to servicing or repair or back into duty. As already mentioned above, the elevator arrangement has a storage channel lc for elevator cars 6 to be transferred to the side, the channel having both waiting space as well as servicing and repair space for the elevator cars 6. The total weight of one elevator car 6 is preferably smaller than the payload of the elevator car 6. In this case a defective elevator car can be transferred, by means of another elevator car, out of the run cycle, e.g. just into the mouth of the storage channel lc.

At the top end and bottom end of the elevator hoistways la, lb is also a separate transfer mechanism, by means of which the elevator cars 6 are transferred from one elevator hoistway to another. In this case an elevator car 6 that has arrived at the topmost floor level 8 is transferred in an essentially horizontal direction from the first elevator hoistway la into the second elevator hoistway lb e.g. in such a way that a short section of the guide rails of the elevator car 6 and a short section of the toothed rack 5 are attached to the transfer mechanism and are transferred by the transfer mechanism from the first elevator hoistway la into the second elevator hoistway lb together with the elevator car 6. At the same time sections of guide rails and of the toothed rack 5 corresponding in size to those that were in the second elevator hoistway displace, without an elevator car, into the first elevator hoistway la. In the first phase of the transfer the power transmission apparatus 7 of the elevator car 6 detaches its grip of the toothed belt 4 moving in one direction and in the last phase the power transmission apparatus 7 grips the toothed belt 4 moving in the other direction. There can be many different types of transfer mechanisms, and they are not relevant from the standpoint of the present invention, so they are not described in more detail than this in this context. The steplessly-operating power transmission apparatus 7 of an elevator car 6 can comprise e.g. a V-belt variator, as is presented in Fig. 2, or two electric machines, in which case one acts as a generator and, controlled by an inverter, drives the other electric machine functioning as an electric motor. A corresponding power transmission apparatus 7 can also comprise e.g. two or three hydraulic machines, such as in Figs. 5 and 6 that present the two embodiments of the invention. In such a case the hydraulic machine 17 coupled to the moving toothed belt 4 acts as a pump and the hydraulic machine 18, 19 coupled to the static toothed belt 5 acts as a hydraulic motor.

As presented in Figs. 5 and 6, the hoisting means 7a and 7b of the power transmission apparatus 7 of each elevator car 6 are composed in this embodiment of two diverting pulleys 12 and 13 fitted at a distance from each other in the vertical direction and of a toothed belt 14 fitted to travel around them. The toothed belt 14 of the first hoisting means 7a is arranged into tooth contact with the moving toothed belt 4 functioning as a traction means and the toothed belt 14 of the second hoisting means 7b is arranged into tooth contact with the toothed rack 5 that is fixed to the inner wall of the elevator hoistway and is essentially static in the vertical direction.

Fig. 5 presents one independently-functioning power transmission apparatus 7 for an elevator car 6, the apparatus being applicable for use in an elevator arrangement according to the invention, the moving machine 7c of which power transmission apparatus is a hydrostatic variator with hydraulic machines 17 and 18. In the moving machine 7c are two hydraulic machines 17 and 18 disposed concentrically in opposite directions to each other, of which the first hydraulic machine 17 functions as an axial piston pump and the second hydraulic machine 18 functions as an axial piston motor. The hydraulic machines 17, 18 are connected to each other with a pressure channel system 20. The drive shaft 17a of the first hydraulic machine 17 is connected via a first coupling 16 to the first hoisting means 7a of the power transmission apparatus 7 via a first gearbox 15 and the drive shaft 18a of the second hydraulic machine 18 is connected via a second coupling 16 to the second hoisting means 7b of the power transmission apparatus 7 via a second gearbox 15.

Fig. 5 presents a situation in which the elevator car 6 is stationary at a floor level and the weight of the elevator car 6 is supported entirely by the second hoisting means 7b on the static toothed rack 5. In this case the second hydraulic machine 18 stays in position adjusted to full displacement per cycle and produces full operating pressure. The same pressure acts via the pressure channel system 20 in the first hydraulic machine 17, but its displacement per cycle is adjusted to zero, so that the torque is also zero and the hydraulic machine 17 rotates idly rotated by the moving toothed belt 4. When the displacement per cycle is increased in the first hydraulic machine 17, it starts to pump hydraulic fluid via the pressure channel system 20 into the second hydraulic machine 18, which consequently starts to rotate. In such a case the elevator car 6 starts to ascend. When the displacement per cycle of both hydraulic machines 17, 18 is adjusted to 50%, the elevator car 6 drives upwards at half the speed of the toothed belt 4. When at the end of the acceleration phase the displacement per cycle of the first hydraulic machine 17 is adjusted to full displacement per cycle, the speed of rotation of the first hydraulic machine 17 is zero and the torque supports the whole weight of the elevator car 6. In this case the elevator car 6 drives upwards at the speed of the toothed belt 4 and the second hydraulic machine 18 rotates at zero displacement without torque.

Fig. 6 presents another independently-functioning power transmission apparatus 7 for an elevator car 6, the apparatus being applicable for use in an elevator arrangement according to the invention, the moving machine 7c of which power transmission apparatus is a hydrostatic variator having three hydraulic machines 17, 18 and 19. The first hydraulic machine 17 of the moving machine 7c acts as an axial piston pump and the two other hydraulic machines 18 and 19 disposed concentrically in opposite directions to each other act as axial piston motors. The second hydraulic machine 18 is a variable displacement axial piston motor and the third hydraulic machine 19 is a fixed displacement axial piston motor. The hydraulic machines 17, 18 and 19 are connected to each other with a pressure channel system 20.

The drive shaft 17a of the first hydraulic machine 17 is connected via a first coupling 16 to the first hoisting means 7a of the power transmission apparatus 7 via a first gearbox 15. Correspondingly, the first hoisting means 7a is coupled via the toothed belt 14 to the moving toothed belt 4.

The drive shaft 18a of the second hydraulic machine 18 is connected via a second coupling 16 to the second hoisting means 7b of the power transmission apparatus 7 via a second gearbox 15, which second hoisting means 7b is further connected via the toothed belt 14 to the first static toothed rack 5. In addition to these, the drive shaft 19a of the third hydraulic machine 19 is connected via a third coupling 16 to the third hoisting means 7b of the power transmission apparatus 7 via a third gearbox 15, which third hoisting means 7b is further connected via the toothed belt 14 to the second static toothed rack 5.

Fig. 6 presents a situation in which the elevator car 6 is stationary at a floor level and the weight of the elevator car 6 is even distributed onto the second and third hoisting means 7b. In such a case both hydraulic machines 18, 19 stay in a stationary position. The toothed belt 4 moves now at double the speed with respect to the arrangement presented in Fig. 5 and the hydraulic machine 17 that is connected to the moving toothed belt 4 and that acts as the pump of the first hoisting means 7a rotates along with the toothed belt 4 while unloading with zero displacement. When the displacement of the first hydraulic machine 17 is increased, the second and third hydraulic machines 18, 19 start to rotate and the elevator car 6 starts to rise upwards along with the motion of the moving belt 4. The speed of the elevator car 6 reaches its peak when the first hydraulic machine 17 pumps hydraulic fluid into the pressure channel system 20 at full displacement. In this case the second hydraulic machine 18 rotates idly at zero displacement and the elevator car 6 drives upwards at half the speed of the toothed belt 4. The supporting of the elevator car 6 has in this case been transferred from the toothed racks 5 to the moving toothed belt 4. An advantage of this solution compared to the solution according to Fig. 5 is that the supporting of a stationary elevator car 6 is distributed evenly to both toothed racks 5, so the support is symmetrical. One drawback, on the other hand, is that the moving machinery 7c is more complex.

Figs. 7-9 present a coupling arrangement between toothed belts 4, 14 and toothed racks 5 applicable to an elevator arrangement according to the invention.

Power transmission between the toothed belt 14 of the power transmission apparatuses 7 and the moving toothed belt 4 functioning as a traction means and also between the toothed belt 14 and the fixed toothed rack 5 can be made to be extremely reliable when the moving toothed belt 4 is provided with small ferromagnetic metallic elements 4e and the toothed belts 14 of the power transmission apparatuses 7 are provided with at least small permanent magnets 14f and preferably also small ferromagnetic metallic elements 14e. The metallic elements 4e and 14e are, in terms of their material, of a suitable ferromagnetic substance, such as e.g. steel. In this case when the toothed belt 14 is up against either the toothed belt 4 or the steel toothed rack 5 the permanent magnets 14f strongly grip the metallic elements 4e or the ferromagnetic toothed rack and the teeth 4c, 14c of the belts 4 and also 14 are able to reliably transmit force from one belt to another, even if the teeth 4c, 14c of the belts were straight.

In the structures according to Figs. 7-9 the moving toothed belt 4 is composed of e.g. an essentially straight back part 4a having a plurality of reinforcements 4b, i.e. cords, in the longitudinal direction of the belt, which cords can be e.g. reinforcements made of carbon fiber, textile fiber, Aramid fiber or polyethylene fiber or steel wire reinforcements or other reinforcements, e.g. composite reinforcements. The back part 4a is on the rear side of the moving toothed belt 4 while on the front side, i.e. the contact side, there is toothing 4c, which can be either straight, inclined or herringbone in shape. At the point of each interval 4d between teeth 4c is a thin metallic element 4e of ferromagnetic material, such as a steel piece, embedded into the back part 4a. Correspondingly, the toothed belt 14 of the power transmission apparatuses 7 is composed e.g. of an essentially straight back part 14a having a plurality of reinforcements 14b, i.e. cords, in the longitudinal direction of the belt, which cords can be e.g. similar to those in the moving toothed belt 4 presented above. The back part 14a is on the rear side of the toothed belt 14 while on the front side, i.e. the contact side, there is toothing 14c, which can be either straight, inclined or herringbone in shape. A permanent magnet 14f is embedded into each tooth 14c and preferably under the permanent magnet 14f, e.g. between the permanent magnet 14f and the back part 14a of the toothed belt 14, a thin metallic element 14e of ferromagnetic material, such as a steel piece, is disposed.

The metallic elements 4e and 14e as well as the magnets 14f are, in the width direction of the belts 4, 14, e.g. the whole width of the belt or only a part of the width of the belt. In the lattermost case, there can be number of metallic elements 4e and 14e as well as magnets 14f one beside another at suitable intervals. A metallic element 14e under the magnet 14f, embedded into a tooth 14c of the toothed belt 14 of the power transmission apparatus 7, functions as a pathway for magnetic flux. Since the magnets 14f are small, thin metallic elements 14e can be used to convey the flux from one magnet to another. In this way the density of the magnetic flux remains high and the force attracting the belts together remains large, in which case the force of attraction of the magnets 14f prevents the tooth forces from pushing a toothed belt 14 apart from a moving toothed belt 4 and from pushing a toothed belt 14 apart from a toothed rack 5.

The toothed belt 14 detaches from the toothed belt 4 and from the toothed rack 5 at the point of the diverting pulleys 12 and 13 of the hoisting means 7a and 7b, one tooth at a time. In principle, pulling a magnet 14f away requires work, but at the same time on the other diverting pulley the magnet 14f comes into contact and performs the same amount of work. Producing magnetic flux in the metallic elements 4e, 14e creates an eddy current, and simultaneously heat loss, which however is so small that it does not stress the coupling arrangement.

The coupling arrangement according to Figs. 7-9 enables an elevator arrangement according to the invention, in which the elevator car 6 climbs upwards along a static toothed rack 5 and also descends downwards along a static toothed rack 5 while conveyed by a moving toothed belt 4. In this case the power transmission from one toothed belt to another succeeds reliably and the toothed belt loop 14 of the hoisting means 7a and 7b can move freely along the longer toothed belt 4 functioning as a traction means fully independently of the speed at which the longer toothed belt 4 is moving.

From the standpoint of the invention, it should be noted that the different solutions presented above can be inventive features together with one or more other features of the invention . It is obvious to the person skilled in the art that the invention is not limited solely to the examples described above, but that it may be varied within the scope of the claims presented below. Thus, for example, some other type of machine than the hydrostatic variators presented in more detail above can be used as the moving machine of the elevator car. The moving machinery can be e.g. mechanical or electrical.

It is also obvious to the person skilled in the art that the toothed belts of the hoisting means of the power transmission apparatuses specific to an elevator car can be different to the toothed belts presented above, which have toothing on both sides of the belt. The belts can be e.g. such that the toothing is on a first side of the belt and on the other side, i.e. the side of the back, the belt is a V-belt, a poly-V belt or a flat belt.