Thermal protection apparatus for electric motors
CA 2296180 A1 · Owner: Berfield, Robert C. · Inventors: Berfield, Robert C.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A thermal protection mechanism for electric motors is disclosed. A brush is urged into electrical contact with a commutator by a primary brush spring. A thermally deformable fastener releasably secures the primary brush spring to a brush housing. A secondary brush spring urges the brush away from the commutator with a force less than that of the primary spring. A thermal overload condition within the motor causes the thermally deformable fastener to substantially deform so that the force exerted on the brush by the primary spring is substantially reduced. The force exerted by the secondary spring overcomes the primary spring so that the brush is forcefully disengaged from electrical contact …
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 January 17, 2000. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended January 17, 2020.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 17, 2022.
- 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.