SE540279C2

SE540279C2 - Elevator drive and elevator system

Info

Publication number: SE540279C2
Application number: SE1551008A
Authority: SE
Inventors: King Fritz
Original assignee: Funiculator Ab
Priority date: 2015-07-10
Filing date: 2015-07-10
Publication date: 2018-05-22
Also published as: WO2017010929A1; SE1551008A1

Abstract

Elevator drive (12) comprising a continuous elongated member (14) for driving at least one carriage (16) along an elevator path (18), the elevator path (18) including an upper section (20), a lower section (22), and at least one substantially straight section (24) vertically between the upper section (20) and the lower section (22); at least one main driving mechanism (26) for driving the elongated member (14); and at least one intermediate driving mechanism (30) for driving the elongated member (14) at an intermediate region (32) of the straight section (24) of the elevator path (18).

Description

ELEVATOR DRIVE AND ELEVATOR SYSTEM Technical Field The present disclosure generally relates to an elevator drive. In particular, an elevator drive comprising at least one intermediate driving mechanism for driving a continuous elongated member and an elevator system comprising the elevator drive are provided.

Background Various types of elevator systems for vertically transporting people and/or goods are known. Some elevator systems employ one or more cables to drive a passenger carriage along a travel path. The cables may be looped around an upper and a lower wheel. One or both of these wheels may be powered to drive the cables and the passenger carriage. It is also known to drive a plurality of passenger carriages on the same cable loop.

The Articulated Funiculator (R) is a new concept of vertical transportation which is described in WO 2013159800 A1. With this concept, two stations in a vertical building or in an underground shaft may be separated by a large distance of, for example, 100 meters.

As the length of the cables is increased between two wheels driving the cables, also the weight imposed on the wheels is increased due to the mass of the cables. The weight of additional carriages further increases the weight to be carried by the wheels and the cables. As a consequence, larger and heavier wheels for driving the cables are needed and large concentrated loads are imposed on the structural system (such as a building). There is also a risk of increased cable fluttering with an increased distance between the wheels.

JP H0930756 A discloses a regrabbing type elevator where four units of elevator cars are driven along a plurality of subloops. One drive wheel is provided in each subloop. With a regrabbing mechanism, the grip is shifted from the rope of one subloop to the rope of another subloop in a regrabbing interval. Thereby, the elevator can handle larger loads. The elevator in JP H0930756 A is however complicated and not suitable for driving the cars at high speed.

Summary Accordingly, one object of the present disclosure is to provide a simple and reliable elevator drive that enables a large separation between stations served by an elevator system and a fast drive of carriages between the stations.

According to one aspect, an elevator drive is provided, where the elevator drive comprises a continuous elongated member for driving at least one carriage along an elevator path, the elevator path including an upper section, a lower section, and at least one substantially straight section vertically between the upper section and the lower section; at least one main driving mechanism for driving the elongated member; and at least one intermediate driving mechanism for driving the elongated member at an intermediate region of the straight section of the elevator path.

The elevator drive thus constitutes a propulsion system for driving an elongated member with one or more carriages attached thereto in an elevator system. The carriages may be passenger carriages and/or load carriages. For example, the carriages may be constituted by pods driven either independently or collectively as trains. Several such trains may be driven by the elongated member.

Each carriage may be permanently attached to the elongated member or may be attachable and detachable thereto in any manner. The continuous elongated member may be constituted by any suitable combination of cables, wires, ropes etc. For example, the elongated member may be constituted by a single cable or by a plurality of parallel cables. The elongated member may extend along the entire or part of the elevator path.

In the case the elevator drive is implemented in an elevator system in a building, the upper section and lower section of the elevator path may be provided adjacent to the top and bottom, respectively, of the building. However, the upper section may be constituted by a top end of a loop of the elevator path, which is not necessarily adjacent to the top of a building. Since the upper section is vertically separated from the lower section, the upper section constitutes a vertically upper section and lower section constitutes a vertically lower section.

The elevator path may be provided in an elevator shaft within a building and/or be provided at the exterior of the building. The elevator path may also be provided in an underground shaft to serve one or more underground stations. The elevator path may for example comprise a track with a pair of rails on which the carriage can roll with wheels. The track may include any combination of straight, curved, twisted and/or helical sections. The elevator path may adopt any type of loop configuration including for example a single vertically elongated loop and several interconnected or separated loops. Thus, the elevator path may comprise one or more loops. For example, the elevator path may adopt an "8-shape" comprising two loops.

The substantially straight section may be constituted by a vertical, horizontal or inclined section of the elevator path. For example, in case the elevator path adopts an "8-shape" with two loops, two vertical straight sections may be provided in each loop and three horizontal straight sections may be provided at the top of the upper loop, at the bottom of the lower loop and between the two loops, respectively. It is also possible to arrange two portions of the elongated member (e.g. an upbound portion and a downbound portion) within one single straight section of the elevator path.

The intermediate region may constitute the entire or any part of the straight section. Several intermediate regions may be provided along one single straight section.

The main driving mechanism may be provided at the upper section and/or at the lower section of the elevator path. The main driving mechanism may be of any type including, for example, a powered driving wheel for driving the elongated member by friction. The mechanism is named "main driving mechanism" since it typically provides more driving power to the elongated member than the intermediate driving mechanisms combined. However, the main driving mechanism may also provide less driving power to the elongated member than the intermediate driving mechanisms combined.

The elevator drive may include two substantially straight sections vertically between the upper section and the lower section and at least one intermediate driving mechanism for driving the elongated member may be positioned adjacent to an intermediate region of each straight section. For this purpose, two intermediate driving mechanisms may be vertically and/or horizontally separated. For example, a first intermediate driving mechanism may be provided at a first straight section and a second intermediate driving mechanism may be provided at a second straight section, vertically separated from the first straight section (e.g. when the elevator path adopts an "8-shape" comprising two loops).

Alternatively, or in addition, a first intermediate driving mechanism may be provided at a first straight section and a second intermediate driving mechanism may be provided at a second straight section, horizontally separated from the first straight section (e.g. when the elevator path comprises an elongated loop). Two or more intermediate driving mechanisms may also be provided at one single straight section.

Furthermore, the elevator path may include two substantially straight sections vertically aligned between the upper section and the lower section and one intermediate driving mechanism may be configured to drive the elongated member at intermediate regions of both straight sections. For this purpose, the intermediate driving mechanism may comprise a continuous driving member with an engaging structure. As an example, the continuous driving member may be rotated such that the driving member engages and drives the elongated member at an intermediate region of a first straight section in a first direction (e.g. upwards) and such that the driving member engages and drives the elongated member at an intermediate region of a second straight section, horizontally opposite to the first straight section, in a second direction (e.g. downwards).

The intermediate driving mechanism may be configured to drive the elongated member substantially linearly along the intermediate region. This linear drive may be performed in a direction substantially parallel with an extension direction of the elongated member at the intermediate region. The intermediate driving mechanism may be configured to simultaneously engage the elongated member at a plurality of engagement points along the intermediate region.

The intermediate driving mechanism may comprise a continuous driving member, such as a belt. The driving member may be wrapped around two rotatable pulleys to form an elongated loop with two substantially straight portions. One of these straight portions may be used to realize the linear drive of the elongated member along the intermediate region. One or both of the pulleys may be powered to drive the driving member of the intermediate driving mechanism. Alternatively, a drive motor may drive the intermediate driving mechanism by engaging the straight portion opposite to the elongated member.

A drive motor may be provided between two intermediate driving mechanisms. The drive motor may engage the intermediate driving mechanisms in the same manner as the intermediate driving mechanisms engage the elongated member at the respective intermediate region. For example, one single drive motor may engage two continuous driving members of two different intermediate driving mechanisms. The drive motor may engage the intermediate driving mechanisms at straight portions opposite to the intermediate region associated with the respective intermediate driving mechanism. However, each intermediate driving mechanism may also have a separate drive motor instead of sharing one.

In case continuous driving members are used in the intermediate driving mechanisms, the drive motor may rotate in a first direction to drive the two intermediate driving mechanisms in a second direction. Thereby, two intermediate regions driven by the respective intermediate driving mechanism at opposite sides to the drive motor may be driven in opposite directions. For example, the motor may be rotated clockwise to drive the two intermediate driving mechanisms on opposite sides of the motor counter clockwise. Thereby, the elongated member may be driven upwards at an intermediate region to the right of the right intermediate driving mechanism and the elongated member may be driven downwards at an intermediate region to the left of the left intermediate driving mechanism.

The elongated member may comprise a plurality of parallel cables interconnected with plate members and the intermediate driving mechanism may comprise at least one paddle member configured to engage the plate members to drive the elongated member. The plate members may be referred to as lifting plates. The plate members may extend between some or all of the parallel cables. In addition, the plate members may extend laterally outside one or both of the outermost cables. A lateral direction is a direction perpendicular to the extension direction of the cables and perpendicular to the parallel direction between the cables. The paddle member may engage the plate member at one or more points on the plate member next to the cables.

The one or more paddle members may be provided on a continuous driving member, such as a belt. In this case, the driving member may be laid around two or more rotatable pulleys. However, the one or more paddle members may also be provided directly on a single drive pulley, i.e. without the provision of a continuous belt. In this case, the drive pulley may be powered or driven by a motor at the opposite side of the intermediate driving mechanism with respect to the elongated member. The drive pulley may however be driven in various ways, such as with an axle.

The intermediate driving mechanism may comprise at least one clamping member configured to clamp the elongated member. The clamping member may be used with an elongated member with or without plate members interconnecting parallel cables of the elongated member. Each clamping member may be electrically or mechanically controlled between a closed state, where the clamping member grasps the elongated member, and an open state, where the elongated member is allowed to pass through the clamping member.

A plurality of paddle members or a plurality of clamping members may be used in an intermediate driving mechanism to realize a simultaneous engagement of the elongated member at a plurality of engagement points along the intermediate region.

The elevator drive may comprise an electric linear motor for driving the elongated member. A primary part of the linear motor may be disposed on the intermediate driving mechanism and a secondary part of the linear motor may be disposed on the elongated member. Thus, the intermediate driving mechanism may be said to comprise a linear motor.

The elevator drive may utilize any combination of intermediate driving mechanisms according to the present disclosure. In particular, any combination of paddle members, clamping members and linear motors may be used for the intermediate driving mechanisms.

According to a further aspect, an elevator system is provided, where the elevator system comprises an elevator drive according to the present disclosure and at least one carriage for being driven by the continuous elongated member. The carriage may be a passenger carriage and/or a load carriage. At least one intermediate driving mechanism may be arranged adjacent to an intermediate floor level. Intermediate floor levels may be used both in buildings and in underground shafts.

More than one propulsion system may be used in the elevator system. For example, in addition to the elevator drive, a further propulsion system may be provided at the stations served by the elevator system that accelerates/decelerates the carriages before/after these are attached/detached to/from the elongated member. The elevator drive may then be driven at a substantially constant speed and mainly used to lift and lower carriages.

The elevator system may comprise four driving motors and serve four stations. In this variant, the motors may constitute two main driving mechanisms adjacent to an upper and a lower station and two drive motors, each for driving two intermediate driving mechanisms adjacent to a station. In the corresponding manner, the elevator system may comprise three or more driving motors for serving the same number of stations, where an upper and lower motor constitute main driving mechanisms and one or more intermediate motors drive opposing intermediate driving mechanisms adjacent to a station.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Brief Description of the Drawings Further details, advantages and aspects of the present disclosure will become apparent from the following embodiments taken in conjunction with the drawings, wherein: Fig. 1: shows a schematic representation of an elevator system comprising an elevator drive; Fig. 2: shows a schematic representation of a further elevator system comprising a further elevator drive; Fig. 3a: shows a schematic representation of an intermediate driving mechanism and an elongated member; Fig. 3b: shows a schematic representation of a plate member of the intermediate driving mechanism in Fig. 3a; Fig. 4a: shows a schematic representation of a further intermediate driving mechanism and an elongated member; and Fig. 4b: shows a schematic representation of a clamping member of the intermediate driving mechanism in Fig. 4a.

Detailed Description In the following, an elevator drive comprising at least one intermediate driving mechanism for driving a continuous elongated member and an elevator system comprising the elevator drive will be described. The same reference numerals will be used to denote the same or similar structural features.

Fig. 1 shows a schematic representation of an elevator system 10 comprising an elevator drive 12. The elevator drive 12 comprises a continuous elongated member 14. The elongated member 14 is constituted by a plurality of parallel cables (only the outermost cable is seen in Fig. 1).

A plurality of carriages 16 are attached to the elongated member 14. Thus, the carriages 16 may be driven by the elongated member 14. The carriages 16 are passenger pods provided with an interior structure movable within an exterior structure in order to maintain passengers standing or seated upright.

As the elongated member 14 is driven, the carriages 16 travel along a common elevator path, indicated by arrows 18. Since the carriages 16 are attached to the elongated member 14, the elevator path 18 substantially corresponds to the path of the elongated member 14. The elongated member 14 may for example be positioned between a pair of rails of a track (not shown) on which the carriages 16 may roll with wheels.

The elevator path 18 includes an upper section 20, a lower section 22 and two substantially straight sections 24 vertically between the upper section 20 and the lower section 22. Each straight section 24 is substantially vertically oriented along the elevator path 18. The elevator path 18 in Fig. 1 adopts a single vertically elongated loop.

The elevator drive 12 in Fig. 1 comprises two main driving mechanisms 26 although only one could also be used. A first main driving mechanism 26 is provided adjacent to the upper section 20 of the elevator path 18 and a second main driving mechanism 26 is provided adjacent to the lower section 22 of the elevator path 18. In Fig. 1, each main driving mechanism 26 is constituted by a powered driving wheel for driving the elongated member 14 by frictional contact therebetween. The upper and lower driving wheels could also use plate members, clamping members or linear motors to drive the elongated member 14.

The elevator drive 12 further comprises a plurality of intermediate driving mechanisms 30. Each intermediate driving mechanism 30 is configured to drive the elongated member 14 at an intermediate region 32 of the straight section 24 of the elevator path 18. As can be seen in Fig. 1, each straight section 24 of the elevator path 18 comprises two vertically separated intermediate regions 32.

In the elevator drive 12 in Fig. 1, four intermediate driving mechanisms 30 are provided. Two upper intermediate driving mechanisms 30 are horizontally separated from each other and two lower intermediate driving mechanisms 30 are horizontally separated from each other. Thus, each intermediate driving mechanism 30 is configured to drive the elongated member 14 at a unique intermediate region 32.

An upper drive motor 34 is positioned horizontally between the two upper intermediate driving mechanisms 30 and a lower drive motor 34 is positioned horizontally between the two lower intermediate driving mechanisms 30. Each intermediate driving mechanism 30 in Fig. 1 comprises a continuous driving member (discussed in detail below) with at least one engaging structure, such as a plate member or a clamping member, for engaging the elongated member 14 and transmit driving power thereto. However, linear motors may also be used to drive the elongated member 14.

As indicated by the arrows in Fig. 1, by driving the drive motors 34 in a counter clockwise direction, each drive motor 34 engages two intermediate driving mechanisms 30 such that the respective continuous driving members are driven in a clockwise direction. Each intermediate driving mechanism 30 in turn engages the elongated member 14 at a respective intermediate region 32 such that the elongated member 14 is driven in the clockwise direction.

Fig. 2 shows a schematic representation of a further elevator system 10 comprising a further elevator drive 12. Mainly differences with respect to Fig. 1 will be described.

The elevator drive 12 in Fig. 2 comprises a continuous elongated member 14 with a plurality of carriages 16 attached thereto. The elevator path 18 comprises two interconnected vertically elongated loops. Thus, the elevator path 18 adopts an "8-shape" with two loops.

The elevator path 18 comprises four substantially straight sections 24. Each straight section 24 is oriented substantially vertically. Two upper straight sections 24 are provided in the upper loop and two lower straight sections 24 are provided in the lower loop.

The elevator drive 12 comprises four intermediate driving mechanisms 30. An intermediate driving mechanism 30 is provided for driving the elongated member 14 at an intermediate region 32 of each of the four straight sections 24. The two upper intermediate driving mechanisms 30 are horizontally separated from each other. Also, the two lower intermediate driving mechanisms 30 are horizontally separated from each other. The two upper intermediate driving mechanisms 30 are vertically separated from the two lower intermediate driving mechanisms 30.

The two loops of the elevator path 18 are interconnected at a crossing region 36. Several supporting wheels 38 may be provided in the crossing region 36 to support and guide the elongated member 14. A station 40 for passengers may be arranged adjacent to the crossing region 36.

When the elongated member 14 is driven, the part of the elongated member 14 in the upper loop of the elevator path 18 is driven in a first direction (clockwise in Fig. 2) and the part of the elongated member 14 in the lower loop of the elevator path 18 is driven in a second direction (counter clockwise in Fig. 2), opposite to the first direction. Therefore, the main driving mechanisms 26, here implemented as powered driving wheels, are driven in opposite directions (if there are two). As a consequence to the layout of the elevator path 18 in Fig. 2, also the drive motors 34 for driving the intermediate driving mechanisms 30 are driven in opposite directions.

Various configurations of the elevator path 18 and the track in and adjacent to the crossing region 36 are possible in order to avoid carriages 16 colliding and enabling exit/entrance for passengers at the station 40 within the crossing region 36. Several stations 40 may be arranged along the elevator path 18, in addition to the top, bottom and crossing region 36.

The layouts of the elevator path 18 and the elongated member 14 illustrated in Figs. 1 and 2 merely constitute illustrative examples. The elevator system 10 may comprise more than one elevator drive 12, the elevator path 18 and the elongated member 14 do not have to be oriented perfectly vertical etc.

Fig. 3a shows a schematic representation of an intermediate driving mechanism 30 and an elongated member 14 and Fig. 3b shows a schematic representation of a plate member 42 of the intermediate driving mechanism 30 in Fig. 3a. The intermediate driving mechanism 30 comprises a continuous driving member 44, here implemented as a belt. An engaging structure in the form of a plurality of paddle members 46 are attached to the driving member 44. The intermediate driving mechanism 30 in Fig. 3a comprises eight paddle members 46. However, the number of paddle members 46 may of course be varied. Each paddle member 46 is directed substantially perpendicular to the surface of the driving member 44.

The intermediate driving mechanism 30 further comprises two rotatable pulleys 48. At least one of the pulleys 48 may be driven to rotate the driving member 44 by frictional contact therewith.

The elongated member 14 comprises a plurality of parallel cables. A plurality of plate members 42 are attached to the elongated member 14, interconnecting the parallel cables. As can be seen in Fig. 3b, the plate member 42 extends between and outside of the cables of the elongated member 14. These surfaces are used by the paddle members 46 to engage the plate members 42 at engagement points 50 to drive the elongated member 14. The paddle members 46 may therefore be regarded as lifting plates.

By rotating the pulleys 48 in the clockwise direction, the driving member 44 and the paddle members 46 attached thereto are driven to rotate. As one paddle member 46 enters the path of the elongated member 14, it engages with a plate member 42 and drives this upwards. The layout of the paddle members 46 and/or the plate members 42 may be varied to provide a reliable drive of the elongated member 14.

As can be seen in Fig. 3a, since the driving member 44 adopts the shape of an elongated loop, it comprises a substantially straight portion parallel with elongated member 14 at the intermediate region 32. Thereby, the intermediate driving mechanism 30 is configured to drive the elongated member 14 substantially linearly along the intermediate region 32 and in a direction substantially parallel with the extension direction of the elongated member 14 at the intermediate region 32.

Furthermore, since the driving member 44 is configured such that a plurality of paddle members 46 are present at the straight portion simultaneously, the elongated member 14 is simultaneously engaged at a plurality of engagement points 50 along the intermediate region 32.

Fig. 4a shows a schematic representation of a further intermediate driving mechanism 30 and an elongated member 14 and Fig. 4b shows a schematic representation of a clamping member of the intermediate driving mechanism in Fig. 4a. Mainly differences with respect to the intermediate driving mechanism 30 in Figs. 3a and 3b will be described.

Instead of paddle members 46, the intermediate driving mechanism 30 in Fig. 4a comprises a plurality of clamping members 52. Each clamping member 52 is configured to clamp at least one cable of the elongated member 14. As can be seen in Fig. 4b, in the illustrated variant, each clamping member 52 is configured to clamp the outer cables of the elongated member 14. However, all cables of the elongated member 14 may be clamped by the clamping member 52.

In case clamping members 52 are employed, the elongated member 14 may or may not comprise plate members 42. If plate members 42 are present on the elongated member 14, the clamping members 52 may clamp the cables of the elongated member 14 between the plate members 42.

Fig. 4b shows that the clamping member 52 comprises two clamping mechanisms 54 for clamping the outer cables of the elongated member 14. In Fig. 4b, the clamping mechanisms 54 are in a closed state, grasping the cables. As indicated by the arrows, the clamping mechanisms 54 of the clamping member 52 may be controlled between this closed state and an open state where the cables of the elongated member 14 is allowed to pass through the clamping member 52. In the open state, the clamping member 52 is also enabled to be moved away from the elongated member 14 to rotate around the upper pulley 48. An electrical or mechanical control of the clamping members 52 may be employed. For example, position sensors may be used to trigger the opening and closing of the clamping members 52.

As an alternative to the above described paddle members 46 and clamping members 52, a linear motor may be employed in the intermediate driving mechanism 30 to drive the elongated member 14.

Due to the intermediate driving mechanisms according to the present disclosure, the load imposed on the drive mechanisms by the elongated member and the carriages can be reduced. The intermediate driving mechanisms also contribute to handle the inertia of the elongated member and the carriages, which may be crucial during starting and stopping procedures. Thereby, a main driving mechanism such as a powered driving wheel can be reduced in terms of power and size.

The elevator drive according to the present disclosure also enables a large separation between stations served by an elevator system and a fast drive of carriages between these stations. Therefore, the elevator drive opens up a wide range of architectural possibilities in buildings and/or underground shafts.

While the present disclosure has been described with reference to exemplary embodiments, it will be appreciated that the present invention is not limited to what has been described above. For example, it will be appreciated that the dimensions of the parts may be varied as needed. Accordingly, it is intended that the present invention may be limited only by the scope of the claims appended hereto.

Claims

1. Elevator drive (12) comprising: - a continuous elongated member (14) for driving at least one carriage (16) along an elevator path (18), the elevator path (18) including an upper section (20), a lower section (22), and at least one substantially straight section (24) vertically between the upper section (20) and the lower section (22); - at least one main driving mechanism (26) for driving the elongated member (14); and - at least one intermediate driving mechanism (30) for driving the elongated member (14) at an intermediate region (32) of the straight section (24) of the elevator path (18); characterized in that the intermediate driving mechanism (30) is configured to drive the elongated member (14) substantially linearly along the intermediate region (32); and in that the intermediate driving mechanism (30) is configured to simultaneously engage the elongated member (14) at a plurality of engagement points (50) along the intermediate region (32).

2. The elevator drive (12) according to claim 1, wherein the elevator path (18) includes two substantially straight sections (24) vertically between the upper section (20) and the lower section (22) and wherein at least one intermediate driving mechanism (30) for driving the elongated member (14) is positioned adjacent to an intermediate region (32) of each straight section (24).

3. The elevator drive (12) according to claim 1 or 2, wherein the elevator path (18) includes two substantially straight sections (24) vertically aligned between the upper section (20) and the lower section (22) and wherein one intermediate driving mechanism (30) is configured to drive the elongated member (14) at intermediate regions (32) of both straight sections (24).

4. The elevator drive (12) according to any of the preceding claims, wherein the intermediate driving mechanism (30) comprises a continuous driving member (44), such as a belt or wheel.

5. The elevator drive (12) according to claim 4, wherein the elongated member (14) comprises a plurality of parallel cables interconnected with plate members (42) and wherein the intermediate driving mechanism (30) comprises at least one paddle member (46) provided on the driving member (44) and configured to engage the plate members (42) to drive the elongated member (14).

6. The elevator drive (12) according to claim 4, wherein the intermediate driving mechanism (30) comprises at least one clamping member (52) provided on the driving member (44) and configured to clamp the elongated member (14).

7. The elevator drive (12) according to any of the preceding claims, wherein the elevator drive (12) comprises an electric linear motor for driving the elongated member (14) and wherein a primary part of the linear motor is disposed on the intermediate driving mechanism (30) and the secondary part of the linear motor is disposed on the elongated member (14).

8. Elevator system (10) comprising an elevator drive (12) according to any of the preceding claims and at least one carriage (16) for being driven by the continuous elongated member (14).

9. The elevator system (10) according to claim 8, wherein at least one intermediate driving mechanism (30) is arranged adjacent an intermediate floor level.