MITSUBISHI ELECTRIC News Releases Mitsubishi Electric Develops Passive Rope-sway Control Device for Elevators in High-rise Buildings
TOKYO, February 7, 2019 – Mitsubishi Electric Corporation (TOKYO: 6503) announced today that it has developed a device that passively controls rope sway when high-rise building elevator sway due to strong winds or long-period earthquakes.
By enabling elevators to continue operating under such conditions, the new device will help to stabilize elevator operations and contribute to greater user convenience.
Mitsubishi Electric’s new passive rope-sway control device applies a magnetic force, called negative stiffness, to the bottom-end of the rope. Negative stiffness is a well-known principle, and it applies a force in the opposite direction against a normal spring’s restoring force.
Main Features
1)More stable elevator operation by greatly suppressing rope sway when building sways
-The magnetic force of permanent magnets is used to amplify the swing of the rope terminal at the top of the car in accordance with the amplitude.
-Lowering the rope’s resonant frequency, or the frequency at which it tends to sway, makes it difficult for the building and ropes to resonate and thereby drastically curbs rope sway.
-By reducing operational downtime, the device helps to stabilize elevator operations.
2)Successful vibration damping tests on actual elevators
A test that simulated a building swaying due to a long-period earthquake demonstrated that, compared to a rope without a passive rope-sway control device, rope sway could be reduced by at least 55% (magnitude of sway at center of undampened rope = 1).
In a test conducted at Mitsubishi Electric’s “SOLAé” elevator test tower (173 meters high) at Inazawa Works. in Japan, the upper end of a rope was shaken at a frequency simulating the sway of a building due to the long-period ground motion of an earthquake. In the absence of any damping device, rope sway exceeded the company’s recommended threshold for suspending elevator operation. When the damping device was applied, however, rope sway fell below the threshold.
http://www.mitsubishielectric.com/news/2019/0207-b.html?cid=rss