On Monday, June 10, at 9.30 a.m. in London, while most of us in the U.S. are fast asleep, the world of vertical transportation may change radically. At that time, KONE, a maker of elevators, will reveal its new system for supertall towers that it promises will “revolutionize the future of building design and urban living.”
It's no surprise that KONE won’t release any details, in advance, about the new elevator system. (I have been asking about it since October, when, in Shanghai to cover the Council on Tall Buildings Congress, I learned something was afoot directly from the horse's mouth.)
KONE will only say it is announcing “new technologies that will take ‘the next leap’ in elevator and building intelligence technology, meeting the demands of ever-higher buildings.”
I have no idea what the system is all about. Unconfirmed reports say the announcement is about a direct-drive system, free of heavy cables that limit the longest travel of current lifts to 560 to 600 m.
I do know that cables, with weight that increases exponentially with building height, have long been the bane of supertower developers and designers.
The longest vertical travel at present is slightly over 500 m at the world’s tallest building—the 828-m-tall Burj Khalifa. That record will soon belong to the under-construction Shanghai Tower, which will have a maximum travel distance of about 560 m. The tower will be 632 m tall.
I don't know whether the KONE system is a direct-drive system, cable-less system. But I asked around for a description of direct drive elevators and also googled the subject. One elevator expert describes a system in this way: "Normally the rails would be static and made from iron. The stator would be copper windings mounted to the car. The alternating current through the windings generates a magnetic field around the rails and produces a force in the up or down direction depending on the phase and magnitude of the current/magnetic field.
"Also [there is] a horizontal force between the motor and rails. It will try to pull the rails and motor together or push them apart depending on the phase of the current. It's like a standard AC induction motor. If you reverse two phases of the three-phase connection, the motor reverses direction."
I also found this in a 2006 presentation paper written by M. Kostelac, Z. Herold and Z. Maljkovićm, in which the authors call direct drives with high torque motors with permanent magnets “a new solution for elevator driving mechanisms. The key advantage of the direct drive is a reduced number of mechanical parts, thus making maintenance easier and cheaper. An additional important advantage is noise reduction during operation, primarily because of reduced number of components that produce noise (gears, belts, worm gears).
"Despite its simple and compact construction, direct drives with high-torque synchronous motors with permanent magnets are not competitive with conventional drives in terms of price primarily because they are custom made, they have high development expenses and there is not all that much production."
Perhaps come June 10, all that will change. We can only wait and see.