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Expired Canadian patentCanada

Method for stopping an electric motor

CA 1295659 C · Owner: Unsworth, Peter J. · Inventors: Unsworth, Peter J.; Rowan, Timothy M.; Merrison, John C.

CIPO record

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Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

An electric motor is braked by sensing the polarity of voltage of the alternating electricity for powering the motor and sensing the polarity of the voltage induced in the motor by the back electromotive force. When these polarities are opposite the electricity is applied to the motor to generate a braking torque. The application of the electricity is stopped a given interval after it begins to be applied during consecutive voltage cycles. This interval is derived from the time period between when braking commenced to when the electricity was applied during consecutive cycle.

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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

  • Granted February 11, 1992. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 11, 2009.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledDecember 21, 1988
GrantedFebruary 11, 1992
Term endedFebruary 11, 2009
Patent numberCA 1295659 C
Classification (IPC)H02P3/18

Timeline

Timeline From CIPO dates

1989199219951998200120042007Application filedDec 21, 1988Patent grantedFeb 11, 1992Term endedFeb 11, 2009

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.