Emergency braking system for a squirrel-cage elevator motor
CA 2037558 C · Owner: Hakala, Harri · Inventors: Hakala, Harri
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A procedure and apparatus are provided for braking a squirrelcage elevator motor fed by a frequency convertor in fault situations using a direct current supplied from a d.c. voltage source. In the procedure of the invention the current in at, least one of the motor phases and the rotational speed of the motor are measured. When the elevator speed exceeds the value corresponding the nominal slip and the motor current is less than the nominal magnetizing current, a switching device is caused to connect a direct current from a d.c. voltage source to the motor, thereby providing a magnetizing current and allowing the motor to act as an eddy current brake.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed March 5, 1991 and granted January 18, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 5, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 5, 2013.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.