Technical Field

This application relates to a capsule for a vertical transportation device. This application also relates to a drive system for a capsule. Further, this application relates to an autonomous capsule having a stator for a linear motor. This application also relates to a vertical transportation device.

Throughout this document both the terms "elevator" and "lift" are used to refer to vertical transportation devices.

Description of the Related Art

As architects and engineers design ever taller buildings the challenge for the vertical transportation designer is how to be able to move a desired number of people and goods to the upper floors of the building without the vertical transportation devices occupying a disproportionate amount of plan core space within the building.

Elevator companies have devised solutions such as double-deck lifts and "twin" lifts (where two lifts cabins travel independently in one shaft) to increase the handling capacity of a single shaft.

To take a simple example, suppose a vertical transportation system comprises a shaft with a capsule which can carry 40 people at a time travelling up 100 floors of a building (the floor to floor distance being 4m) at an average speed of lOm/sec. Suppose also that the downward journey of the capsule has an average speed of 10m/sec. Such a system would be able to carry 40 people up 100 floors every 80 seconds (the time to travel up the building from ground level to level 100 and back to ground level). This rate is equivalent to 1800 persons per direction per hour. A similar system with two such shafts each having one capsule would be able to carry 3600 persons per direction per hour. Of course taller buildings require more shafts and capsules to provide appropriate carrying capacity of people and goods to the upper floors. However, each shaft occupies a significant area of floor, so the taller the building the more lift shafts are needed and so less floor area is available for use.

US 2006/0163008, incorporated herein by reference, describes an autonomous linear retarder/motor for a direct drive gearless and ropeless elevator. Retarders are fixed to the passenger cabin such that under free fall conditions the gross weight of the passenger cabin is counter-balanced by a force generated in the retarders. Free-fall conditions may be encountered due to power failure. The retarders thus permit the passenger cabin to descend at a slow speed until resting on its buffers. The retarder unit can also function as a motor by applying an appropriate voltage to a stator of the retarder. The retarder unit also includes an uninterruptible power supply (UPS) unit capable of supplying the retarder with sufficient power for a few seconds to permit the passenger cabin and passengers to slowdown comfortably from high speed. Both are fed from an onboard continuously charged battery unit which also provides power supply to the logic control circuits and switches.

The retarder of US 2006/0163008 is described in the context of a known lift assembly wherein multiple passenger cabins can use a single shaft. In the example shown, two lift shafts are provided, an up-shaft and a down-shaft. Transfer mechanisms are provided at the top and bottom extents of the shafts to transfer passenger cabins between the two shafts. The top transfer mechanism lifts the passenger cabin out of the up-shaft and propels the passenger cabin sideways until it is over the down-shaft. The passenger cabin is then lowered into the down-shaft. Similarly, the bottom transfer mechanism lowers the passenger cabin out of the down-shaft and propels the passenger cabin sideways until it is under the up-shaft. The passenger cabin is then raised into the up-shaft.

A problem with such a lift assembly is that of how to deliver the required power to the passenger cabins. By way of example, a cabin ascending at 6m/s carrying 20 people requires approximately 25OkW. Clearly, in a system with multiple lifts per shaft as described above, a cable and counterweight operated system would be at least cumbersome, if not impractical. Such a lift assembly is possible using linear motors. A suitable motor would be a linear synchronous motor (LSM), which has a stator or active winding cooperating with a magnetic rail. The stator is separated from the magnetic rail by an air gap. The magnetic rail is usually created using permanent magnets.

In vertical transportation devices, the stator may extend along the length of the shaft with the magnetic rail attached to the passenger cabin. Such a system may be described as "fixed stator". A problem with such a system is that a large amount of power must be fed into the appropriate point of the stator track, along the entire height of the shaft. Further, the hardware for controlling the power distribution to the stator track must be distributed along the height of the shaft. Such hardware includes inverters, coils and switching circuitry at least. Particularly in the case of multiple lifts per shaft, complex control circuitry will be required to ensure that the substantially passive passenger cabins move as required. Also, passenger cabins require some on-board power for systems such as passenger control panels, lighting and air conditioning; fixed stator systems do not easily account for this. As an alternative to fixed stator systems, a "fixed magnet" system could be used. In a fixed magnet system the stator is attached to the passenger cabin with the magnet rail extending the length of the shaft forming a magnetic track. In such a system a trailing electrically conducting (and insulated) cable can be used to provide power to the passenger cabin allowing it to control and power the stator in order to propel the passenger cabin. However, where multiple passenger cabins can use the same shaft, trailing cables are not suitable. Current collectors (i.e. live rails with brushes or electrical pickups attached to the passenger cabin) are unsafe and impractical for powering a vertical transportation device. A possible solution is to use inductive coupling, wherein in addition to the magnetic track, a series of coils extend along the length of the shaft. These coils are appropriately powered such that a pick up coil on the passenger cabin can obtain sufficient electrical power to drive the stator part of the linear motor. In the above fixed magnet systems, the means for delivering power to the stator of the passenger cabin may also be used to provide power to the on-board systems such as passenger control panels, lighting and air conditioning.

Embodiments of the apparatus and methods disclosed herein seek to provide an improved power supply arrangement for a vertical transportation device.

Summary

According to a first aspect there is provided a capsule for a vertical transportation device. The capsule comprises a stator for cooperation with a magnetic track for driving the capsule and at least one capacitive device for providing power to the stator for driving the capsule. Embodiments of such a capsule allow a vertical transportation system having multiple capsules per shaft without complex power delivery systems for providing power to the capsules.

The stator for cooperation with a magnetic track may also be for retarding the capsule, and wherein the at least one capacitive device may receive power from the stator for retarding the capsule. The at least one capacitive device may accumulate charge when receiving power from the stator.

Embodiments of such a capsule allow the capacitive device to be recharged during its descent, substantially recovering the gravitational potential energy acquired during the ascent of the capsule.

The capsule may further comprise electrical contacts for receiving power from charge connections external to the capsule. The electrical contacts may be arranged to provide a top-up charge to the at least one capacitive device. I

The at least one capacitive device may have an energy density greater than 200 Joules per gram. The at least one capacitive device may have an energy density greater than 500 Joules per gram. The at least one capacitive device may have an energy density greater than 1000 Joules per gram.

Brief Description of the Drawings

Embodiments of the present invention will now be described, by way of example only, with reference to the attached drawings, in which:

Figure 1 shows a vertical transport system; and

Figure 2 shows a passenger cabin of a vertical transport system incorporating the power delivery system disclosed herein. Detailed Description of the Drawings

Figure 1 shows a vertical transport system 100 comprising a plurality of capsules 110. In the figure each capsule 110 is a passenger cabin. The vertical transport system 100 further comprises an up shaft 112, a down shaft 114, a top transfer mechanism 116, and a bottom transfer mechanism 118.

The passenger cabins feature linear motors comprising stators 120, guide wheels 122, and magnetic tracks 124. The passenger cabins also feature failsafe brakes which comprise calliper brakes arranged to provide an appropriate stopping force. The calliper brakes are incorporated into the linear motor arrangement. However, stopping an elevator mid- shaft under emergency power failure condition is not a satisfactory situation as far as the passengers are concerned as they become trapped. A role of the linear motors is to ensure that when the fail safe elevator brakes are lifted the elevator moves slowly downward to an exit level where the trapped passengers can be released. The motor unit can act as a retarder and provide a retardation force to decelerate a descending cabin at an appropriate rate, and can also providing the requisite motoring power to permit an ascending cabin to continue upward at an appropriate speed for several seconds to allow deceleration at an appropriate rate that would be comfortable for the passengers. Each motor comprises three tuned stator sections, Sl, S2, S3, each one meter in length located between the poles of permanent magnets arranged along a magnetic track 124 that extends top to bottom of the elevator shafts 112, 114. Typically, a single stator section is located in its permanent magnet track with an air gap of approximately 3 mm either side. A single 1 meter section can either produce 4000 Newtons of retarding force or alternatively 4000 Newtons of motoring force for slowdown from high speed in the up direction. In each three meter length of linear motor a battery may be incorporated to operate a fail safe calliper type brake.

In a vertical transportation device as disclosed herein, a capacitive device is used as the primary power delivery system to provide power to the stator of a fixed magnet linear motor system. The capacitive device is carried by the passenger cabin and may be used instead of or in conjunction with an emergency power supply. During ascent of the passenger cabin the capacitive device provides power to the stator 120. In this way, the passenger cabin may make an upward journey without receiving power from an external source after it has left the ground floor. The capacitive device receives a full charge or a top-up charge at the lowest point of its cycle. The charge is delivered to the capacitive device from an external power source via electrical contacts on the passenger cabin.

In descent of the passenger cabin, the linear motor may be used as a generator by connecting an electrical load to the stator. The linear motor then acts to retard the descent of the cabin and to generate electricity, which is used to recharge the capacitive device. Thus, in a complete ascent and descent cycle of the passenger cabin, the capacitive device loses only a small proportion of its charge, the proportion dependent on the motor and generator efficiency, and losses due to, for example, friction. Top-up charging is also required to replace the power consumed by the on-board electrical systems of the passenger cabin during its cycle around the shafts. This charge loss is overcome by top-up charging the capacitive device at least once during a cycle of ascent and descent. This charge takes place at the bottom of the cycle to ensure the passenger cabin has enough energy to reach the top of the building. Figure 2 shows a capsule 110 in accordance with the vertical transportation device disclosed herein. The capsule 110 has linear motors/retarders (120, 122) as described above. The capsule 110 also has a capacitive device 132, control circuitry 134, and electrical contacts 130 for top-up charging.

The capacitive device is used instead of a chemical battery primarily because of the fast re-charge capability of a capacitive device as compared to a chemical battery. The fast recharge capability has the advantage that recovered energy on the descent can be easily stored, and that the capsule 110 can receive its top- up charge quickly, thus improving the handling capacity of the vertical transport system.

An example of an appropriate capacitive device 132 for use with the system disclosed herein is described in US 7,033,406, incorporated herein by reference. This document describes an electrical-energy-storage unit (EESU). The EESU has a high-permittivity composition-modified barium titanate ceramic powder as a basis material. This powder is coated twice, the first coating being aluminum oxide and the second coating calcium magnesium aluminosilicate glass. The components of the EESU are manufactured with the use of classical ceramic fabrication techniques which include screen printing alternating multilayers of nickel electrodes and high-permittivitiy composition- modified barium titanate powder, sintering to a closed-pore porous body, followed by hot-isostatic pressing to a void-free body. The components are configured into a multilayer array with the use of a solder-bump technique as the enabling technology so as to provide a parallel configuration of components that has the capability to store electrical energy in the range of 52 kWh or 187 MJ. The total weight of an EESU with this range of electrical energy storage is about 152 kg. The EESU described above has an energy density of around 1230 J/g. We will now consider this in relation to the earlier example of a 20 person lift travelling at a speed of 6 m/s and requiring 250 kW. Given a 40 second journey to the top of a 240 m building, then the energy required is 10 MJ. This may be provided by a 9 kg EESU. In practice a mach larger EESU is used in order to allow for multiple stops (and the associated acceleration and deceleration) and to allow sufficient power for the on-board systems of the capsule.

The capacitive device 132 may be used to power the transfer mechanisms that transfer the capsules 110 between shafts. To do this, each capsule 110 requires additional drive components to propel the capsule sideways at the appropriate point.

An EESU as described above operates at voltages up to 3500 V. Accordingly, control circuitry 134 includes conversion circuitry for stepping down this voltage for driving the motors and stepping up this voltage for charging the EESU when the linear motor is used as a generator.

The method and apparatus disclosed herein has been described in the context of a vertical transport system. It should be understood that the method and apparatus disclosed herein may also be applied to transport systems that operate substantially vertically or on any incline.

Embodiments of the present invention have been described with particular reference to the examples illustrated. However, it will be appreciated that variations and modifications may be made to the examples described without departing from the scope of the present invention.