EP1997706B1

EP1997706B1 - Cable transportation system and relative operating method

Info

Publication number: EP1997706B1
Application number: EP08157368A
Authority: EP
Inventors: Mark Lohr
Original assignee: Rolic Invest SARL
Current assignee: Rolic Invest SARL
Priority date: 2007-06-01
Filing date: 2008-05-30
Publication date: 2011-03-30
Anticipated expiration: 2028-05-30
Also published as: ITMI20071131A1; EP1997706A1; ES2361956T3; ATE503671T1

Abstract

A cable transportation system (1) having a cable (2) moved along a first path (P1); a number of transportation units (3) connectable selectively to the cable (2); a turnaround station (4) having a transportation device (5), which is equipped with positively-driven rollers (16) extending along a second path (P2) at the turnaround station (4) to move the transportation units (3) detached from the cable (2), and has a first portion (10; 13) for accelerating or decelerating the transportation units (3), and a second portion (11; 12) adjacent to the first portion (10; 13) and driven by the first portion (10; 13) via a mechanical drive (15) having a velocity ratio selectively variable as a function of a signal emitted by a control device (6) for monitoring the distance between the transportation units (3).

Description

The present invention relates to a cable transportation system.
More specifically, the present invention relates to a cable transportation system comprising a cable moved along a first path; a number of transportation units connectable selectively to the cable; a turnaround station comprising a transportation device, which is equipped with positively-driven rollers extending along a second path at the turnaround station to move the transportation units detached from the cable, and comprises a first portion for accelerating or decelerating the transportation units, and a second portion adjacent to the first portion; and a control device for monitoring the distance between the transportation units.
Cable transportation systems of the above type are normally used for passenger transport between two turnaround stations, and the tendency in this sector is to increase passenger-carrying capacity per unit of time by increasing the carrying capacity and reducing the distance between the transportation units along the cable. These measures, however, are limited by the risk of collision of the transportation units at the turnaround station.
More specifically, at the turnaround station, the transportation units are detached from the cable and moved by the transportation device, which engages the transportation units with drive rollers, slows down the transportation units to a speed enabling passengers to board and alight easily, and then accelerates the transportation units to the same speed as the cable before they are reconnected to the cable.
Being driven frictionally by the rollers, the distance between the transportation units may vary, thus possibly resulting in collision of the transportation units - a risk commonly encountered in the case of chair-lifts.
In fact, the tendency with chair-lifts is to make increasingly wide chairs (chairs with eight seats in a row are now widely used) to increase the carrying capacity of each chair and the system as a whole. The path at the turnaround station, however, has often very tight curved portions, which greatly increases the risk of the ends of two chairs colliding.
To prevent collision of the transportation units, each turnaround station comprises a control device for monitoring the distance between the transportation units travelling through the station, and, when the distance reading is below a given threshold value, the system is stopped.
Accordingly, the first deceleration portion is connected to a second portion by a mechanical drive - in this case, a clutch - to transfer motion from the rollers of the first portion to the rollers of the second portion.
In the event of possible collision, the clutch is released to prevent the transportation units from travelling along the second portion.
The clutch, however, even though sometimes assisted by a brake, fails to provide for rapidly stopping the transportation units, which, because of their own inertia and that of the rollers, continue travelling along part of the path. As a result, each transportation unit has a long braking distance, which prevents any further reduction in the distance between the transportation units and, hence, any further increase in passenger-carrying capacity.
US 4,744,506 teaches driving the first portion and the second portion separately by means of an high number of motors. Such a solution is too expensive to be implemented.
US 4,942,823 teaches driving the first and second portions by means of a single motor and two respective mechanical drives. The mechanical drive connecting the motor to the second portion includes clutches and cannot rapidly stop the second portion.
It is an object of the present invention to provide a cable transportation system of the above type, designed to eliminate the drawbacks of the known art, and which in particular is cheap to produce-According to the present invention, there is provided a cable transportation system comprising a cable moved along a first path; a number of transportation units connectable selectively to the cable; a turnaround station comprising a transportation device, which is equipped with positively-driven rollers extending along a second path at the turnaround station to move the transportation units detached from the cable, and comprises a first portion for accelerating or decelerating the transportation units, and a second portion adjacent to the first portion; and a control device for monitoring the- distance between the transportation units; the cable transportation system being characterized in that the second portion is driven by the first portion via a mechanical drive that has a velocity ratio selectively variable as a function of a signal emitted by the control device and correlated to the distance between the transportation units and comprises a mechanical gear drive with two degrees of freedom.
The velocity ratio may thus be zeroed rapidly to greatly reduce the braking distance along the second portion; and, when the system is stopped, the drive may be used to reposition the transportation units the given distance apart.
The present invention also relates to a method of operating a cable transportation system.
According to the present invention, there is provided a method of operating a cable transportation system, the method comprising the steps of moving a cable along a first path to transfer a number of transportation units, selectively connectable to the cable, between two turnaround stations; moving the transportation units, detached from the cable, along a second path at a turnaround station by means of a transportation device, which is equipped with positively-driven rollers extending along a second path at the turnaround station, and comprises a first portion for accelerating or decelerating the transportation units, and a second portion adjacent to the first portion; and monitoring the distance between the transportation units by means of a control device; the method being characterized by driving the second portion by the first portion via a mechanical drive; and selectively varying the velocity ratio of the mechanical drive as a function of a signal emitted by the control device and correlated to the distance between the transportation units; the mechanical drive comprising a mechanical gear drive with two degrees of freedom
A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a schematic plan view, with parts removed for clarity, of a cable transportation system in accordance with the present invention;
Figure 2 shows a larger-scale plan view, with parts removed for clarity, of a detail of Figure 1;
Figure 3 shows a larger-scale plan view, with parts in section and parts removed for clarity, of a detail of Figure 1 system.

Number 1 in Figure 1 indicates as a whole a cable transportation system comprising a cable 2 extending along an endless path P1; a number of transportation units 3, only one of which is shown by a dash line in Figure 1; two turnaround stations 4, only one of which is shown in Figure 1; a transportation device 5 at turnaround station 4; and a control device 6 for monitoring the distance between transportation units 3 and controlling transportation device 5.
At turnaround station 4, cable 2 is looped about a pulley 7 of axis A1, and feeds transportation units 3 into turnaround station 4, where each transportation unit 3 is detached, in known manner not shown, from cable 2 and moved by transportation device 5 along a path P2.
Each transportation unit 3 - which, in the Figure 1 example, comprises an eight-seater chair - comprises a known releasable clamp, not shown, which, in known manner not shown, is detached from cable 2 on entering turnaround station 4, and is connected to cable 2 on leaving turnaround station 4.
Turnaround station 4 comprises a frame 8 in turn comprising a U-shaped overhead beam 9, along which path P2 substantially extends.
Transportation device 5 is supported by beam 9 and divided into four portions 10, 11, 12, 13 arranged successively along path P2. Portion 10 provides for decelerating transportation units 3, portions 11 and 12 for generally moving transportation units 3 along at constant speed, and portion 13 for accelerating transportation units 3 to the same speed as cable 2. Portions 10 and 13 are straight, and are driven by cable 2 by means of respective drive devices 14; whereas portions 11 and 12 are at least partly curved, and are driven by portions 10 and 13 by means of respective mechanical drives 15.
There is no connecting mechanism between portions 11 and 12, so portions 10 and 11 are separated mechanically from portions 12 and 13.
With reference to Figure 2, each of portions 10 and 11 - and likewise also portions 12 and 13 not shown - comprises a succession of rollers 16, each of which rotates about an axis A2 and comprises a tyre 17 for pushing transportation units 3 by friction along path P2. As shown more clearly in Figure 3, rollers 16 of portion 10 are supported by respective axles 18 fixed to beam 9, and are connected to one another by pulleys 19 and 20 and belts 21.
In other words, each roller 16 comprises two pulleys 19 and 20, and is connected by a belt 21 to the preceding roller 16, and by a belt 21 to the following roller 16. The ratio between the radii of pulleys 19 and 20 provides for achieving the desired motion along path P2 : deceleration along portion 10, constant speed along portions 11 and 12, and acceleration along portion 13.
Along the curved portions of path P2, motion is transferred between rollers 16 by bevel gears 22 and 23. Each roller 16 along a curved portion of path P2 comprises a bevel gear 22, and is connected to the preceding roller 16 by a bevel gear 23 supported by beam 9, and is connected to the following roller 16 by a bevel gear 23.
With reference to Figure 3, mechanical drive 15 has a variable velocity ratio, is supported by beam 9, and is located between and over portions 10 and 11. An identical drive is located between portions 12 and 13. Mechanical drive 15 comprises a boxlike supporting structure 24 fixed to beam 9; an electric motor 25 controlled by control device 6; an input pulley 26 connected by a respective belt 27 to pulley 19 of a roller 16 of portion 10; an output pulley 28 connected by a respective belt 29 to pulley 20 of a roller 16 of portion 11; an epicyclic gear train 30; and a brake 31.
Epicyclic gear train 30 is housed in boxlike supporting structure 24, is connected to motor 25 by two gears 32, 33 - in the example shown, a worm and a helical gear defining a reducer - and extends along an axis A3 parallel to axes A2 of rollers 16 underneath.
Epicyclic gear train 30 comprises a carrier 34 fixed to output pulley 28; an internally toothed ring gear 35 mounted to rotate about carrier 34 and fixed to input pulley 26; a shaft 36 supporting a sun gear 37 and connected to electric motor 25; and planet gears 38, each supported by carrier 34 and located between sun gear 37 and ring gear 35. Brake 31 is indicated schematically by an electric terminal 39, and by an actuator 40 which acts on electric motor 25.
The velocity ratio of rollers 16 connected directly by mechanical drive 15 is 1:1, and can be varied by releasing brake 31 and operating motor 25.
With reference to Figure 1, control device 6 comprises a number of sensors 41 - in the example shown, proximity sensors - arranged along path P2 to emit signals on detecting passage of a transportation unit 3; and a control unit 42, which receives and processes the signals from sensors 41, and emits signals for controlling electric motors 25 and brakes 31.
Detection of successive transportation units 3 travelling past each sensor 41 produces time intervals which are compared with reference values.
Control unit 42 comprises a clock 43 which, together with each sensor 41, determines time intervals relative to passage of transportation units 3; and a comparing block 44, in which the time intervals detected by each sensor 41 are compared with a threshold value : when the detected interval is below the threshold value, control unit 42 emits a signal to release brake 31 and operate electric motor 25.
The speed of electric motor 25 and the selected velocity ratio of gears 32 and 33 are such that operation of the motor stops ring gear 35 and therefore all the rollers 16 of portion 11. Similarly, operation of motor 25 and release of brake 31 of drive 15 between portions 12 and 13 stop rollers 16 of portion 12.
The solution described has the big advantage of rapidly stopping rollers 16 of portions 11 and 12, by electric motor 25 rapidly reaching steady-operating speed and so preventing rollers 16 from rolling along further by inertia.
In a variation of the present invention, electric motor 25 is a variable-speed electric motor capable of slowing portion 11 with respect to portion 10, and portion 12 with respect to portion 13, and so reestablishing the desired distance between transportation units 3.
In a further variation, electric motor 25 is reversible, in the sense of rotating in two opposite directions, to accelerate, if necessary, portions 11 and 12 with respect to respective portions 10 and 13.
In other words, epicyclic gear train 30 may be replaced by any type of gear train with two degrees of freedom, without departing from the scope of the present invention.
In actual use, the velocity ratio of the differential mechanical drive with two degrees of freedom is varied by electric motor 25, the speed of which depends on the signal emitted by control unit 42.
Brake 31 is released simultaneously with start-up of motor 25.
In one operating mode of the present invention, mechanical drive 15 is used solely as a brake to rapidly stop second portions 11 and 12 : the signal activating motor 25 is an on/off signal, and motor 25 is operated at maximum speed to produce a zero velocity ratio of mechanical drive 15.
In a second operating mode, the speed of electric motor 25 is modulated to modulate the velocity ratio of mechanical drive 15 between zero and one.
Mechanical drives 15 may also be used to reposition transportation units 3 the given distance apart.

Claims

A cable transportation system (1) comprising a cable (2) moved along a first path (P1); a number of transportation units (3) connectable selectively to the cable (2); a turnaround station (4) comprising a transportation device (5), which is equipped with positively-driven rollers (16) extending along a second path (P2) at the turnaround station (4) to move the transportation units (3) detached from the cable (2), and comprises a first portion (10; 13) for accelerating or decelerating the transportation units (3), and a second portion (11; 12) adjacent to the first portion (10; 13); and a control device (6) for monitoring the distance between the transportation units (3); the cable transportation system (1) being characterized in that the second portion (11; 12) is driven by the first portion (10; 13) via a mechanical drive (15) that has a velocity ratio selectively variable as a function of a signal emitted by the control device (6) and correlated to the distance between the transportation units (3) and comprises a mechanical gear drive (30) with two degrees of freedom.
A system as claimed in Claim 1, characterized in that the mechanical drive (15) comprises a differential mechanical gear drive (30) with two degrees of freedom.
A system as claimed in Claim 1, characterized in that the mechanical drive (15) comprises an epicyclic gear train (30).
A system as claimed in any one of the foregoing Claims, characterized in that the mechanical drive (15) comprises an electric motor (25) activated selectively by the signal emitted by the control device (6) to vary the velocity ratio of the mechanical drive (15).
A system as claimed in any one of the foregoing Claims, characterized in that the mechanical drive (15) comprises a first shaft (36) connected to the electric motor (25); and a brake (31) to lock the first shaft (36) as a function of a further signal emitted by the control device (6).
A system as claimed in Claim 5, characterized in that the mechanical drive (15) comprises an input pulley (26) connected to the first portion (10; 13) and to the mechanical gear drive (30); and an output pulley (26) connected to the second portion (11; 12) and to the mechanical gear drive (30).
A system as claimed in any one of the foregoing Claims, characterized in that the first portion (10; 13) is straight, and the second portion (11; 12) is at least partly curved.
A system as claimed in any one of the foregoing Claims, characterized in that the transportation device (5) comprises two first portions (10; 13) and two second portions (11; 12) complementary with one another to define the whole second path (P2).
A system as claimed in any one of the foregoing Claims, characterized in that the control device (6) comprises a control unit (42); and a number of sensors (41) for determining the position of the transportation units (3) along the second path (P2).
A method of operating a cable transportation system (1), the method comprising the steps of moving a cable (2) along a first path (P1) to transfer a number of transportation units (3), selectively connectable to the cable (2), between two turnaround stations (4); moving the transportation units (3), detached from the cable (2), along a second path (P2) at a turnaround station (4) by means of a transportation device (5), which is equipped with positively-driven rollers (16) extending along a second path (P2) at the turnaround station (4), and comprises a first portion (10; 13) for accelerating or decelerating the transportation units (3), and a second portion (11; 12) adjacent to the first portion (10; 13); and monitoring the distance between the transportation units (3) by means of a control device (6); the method being characterized by driving the second portion (11; 12) by the first portion (10; 13) via a mechanical drive (15); and selectively varying the velocity ratio of the mechanical drive (15) as a function of a signal emitted by the control device (6) and correlated to the distance between the transportation units (3); the mechanical drive (15) comprising a mechanical gear drive (30) with two degrees of freedom.
A method as claimed in Claim 10, characterized in that the mechanical drive (15) comprises a differential mechanical gear drive (30) with two degrees of freedom, in particular an epicyclic gear train (30); the method varying the velocity ratio by means of an electric motor (25) connected to the mechanical gear drive (30) .
A method as claimed in Claim 11, characterized by comprising the step of selectively locking one degree of freedom of the mechanical gear drive (30) by means of a brake (31) and a further signal emitted by the control device (6) and correlated to the distance between the transportation units (3).
A method as claimed in any one of Claims 10 to 12, characterized by zeroing the velocity ratio of the mechanical drive (15) to stop the second portion (11; 12).
A method as claimed in any one of Claims 10 to 12, characterized by imposing a velocity ratio ranging between zero and one .