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19 April, 2018

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Linear motors cure the high-rise shakes

01 March, 2002

Linear motors cure the high-rise shakes

High-speed elevators suffer from a design problem - small deformations or misalignments in their guide rails can make then vibrate vigorously from side-to-side, making passengers feel uncomfortable.

Various techniques have been applied to tackle this problem, including the use of damping technologies, and machining and installing the guide rails to a precision of better than 1mm. But these approaches can be costly and are of limited effectiveness when the lifts are travelling at high speeds.

Engineers working for Mitsubishi in Japan have therefore come up with an alternative technique which uses linear motors to stabilise the passenger compartment as it moves. They claim that their system, which can be fitted to new or existing lifts, can cut lateral movements by more than half.

The system uses accelerometers to sense the minuscule lateral vibrations. It feeds this information to a small electronics package which controls a pair of active roller guides attached to the bottom of the lift. The guides use high-performance permanent magnet linear motors to compensate for the vibrations. The motors draw less than 20W.

Mitsubishi says that the system will allow lifts to travel at more than 5m/s, with lateral vibration levels of just 10cm/s2 - less than half the usual level. The active damping system will have its debut at an elevator exhibition in China in April, and its first commercial installation will be in a high-rise building due for completion during 2003.




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