US3719798A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermostatically controlled heating implement
Assignee: 3M Co
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Filing: 1971-02-19
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Granted: 1973-03-06
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Expires: 1991-02-19
Abstract
Abstract A thermostatically controlled heating implement in which one surface of a formed sheet of metal defines the heating surface of the implement and in which the formed sheet forms one element in a bimetal bow-type thermomechanical switch to control the heating temperature of the implement.
Inventors
- 👤 D Nelson
- 👤 T Shevlin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 09:10
CPC Classifications
H; H01; H01H; H01H37/00; H01H37/02; H01H37/32; H01H37/52; B; B01; B01L; B01L7/00
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
246 words
A thermostatically controlled heating implement comprising: a frame including a formed sheet of metal having a relatively high coefficient of thermal expansion, one surface of said formed sheet defining a heating surface of said implement, means for heating said Formed sheet to heat substances contacting said heating surface thereof, a strip of metal having a relatively low coefficient of thermal expansion rigidly secured at its ends to the surface of said formed sheet opposite said heating surface, said points of securement of said metal strip being spaced a lesser distance than the length of said metal strip between them to bow said metal strip away from said opposite surface of said formed sheet, and means for controlling said means for heating in response to changes in the bowing of said metal strip to cause heating of said formed sheet when the bowing of said metal strip is greater than a predetermined minimum extent, whereby when the temperature of said formed sheet is below a preset temperature it has lesser dimensions, said strip of metal is bowed away from said opposite surface of said formed sheet greater than said predetermined minimum extent and said means for controlling activates said means for heating; as said formed sheet is heated it expands thereby causing said metal strip to be less bowed and when the temperature of said formed sheet reaches said preset temperature said metal strip is bowed said predetermined minimum extent and said means for heating is deactivated.
Claim 2
Dependent Claim
246 words
A thermostatically controlled heating implement comprising: a frame including a formed sheet of metal having a relatively high coefficient of thermal expansion, one surface of said formed sheet defining a heating surface of said implement, means for heating said Formed sheet to heat substances contacting said heating surface thereof, a strip of metal having a relatively low coefficient of thermal expansion rigidly secured at its ends to the surface of said formed sheet opposite said heating surface, said points of securement of said metal strip being spaced a lesser distance than the length of said metal strip between them to bow said metal strip away from said opposite surface of said formed sheet, and means for controlling said means for heating in response to changes in the bowing of said metal strip to cause heating of said formed sheet when the bowing of said metal strip is greater than a predetermined minimum extent, whereby when the temperature of said formed sheet is below a preset temperature it has lesser dimensions, said strip of metal is bowed away from said opposite surface of said formed sheet greater than said predetermined minimum extent and said means for controlling activates said means for heating; as said formed sheet is heated it expands thereby causing said metal strip to be less bowed and when the temperature of said formed sheet reaches said preset temperature said metal strip is bowed said predetermined minimum extent and said means for heating is deactivated.
Claim 3
Dependent Claim
246 words
A thermostatically controlled heating implement comprising: a frame including a formed sheet of metal having a relatively high coefficient of thermal expansion, one surface of said formed sheet defining a heating surface of said implement, means for heating said Formed sheet to heat substances contacting said heating surface thereof, a strip of metal having a relatively low coefficient of thermal expansion rigidly secured at its ends to the surface of said formed sheet opposite said heating surface, said points of securement of said metal strip being spaced a lesser distance than the length of said metal strip between them to bow said metal strip away from said opposite surface of said formed sheet, and means for controlling said means for heating in response to changes in the bowing of said metal strip to cause heating of said formed sheet when the bowing of said metal strip is greater than a predetermined minimum extent, whereby when the temperature of said formed sheet is below a preset temperature it has lesser dimensions, said strip of metal is bowed away from said opposite surface of said formed sheet greater than said predetermined minimum extent and said means for controlling activates said means for heating; as said formed sheet is heated it expands thereby causing said metal strip to be less bowed and when the temperature of said formed sheet reaches said preset temperature said metal strip is bowed said predetermined minimum extent and said means for heating is deactivated.
Claim 4
Dependent Claim
246 words
A thermostatically controlled heating implement comprising: a frame including a formed sheet of metal having a relatively high coefficient of thermal expansion, one surface of said formed sheet defining a heating surface of said implement, means for heating said Formed sheet to heat substances contacting said heating surface thereof, a strip of metal having a relatively low coefficient of thermal expansion rigidly secured at its ends to the surface of said formed sheet opposite said heating surface, said points of securement of said metal strip being spaced a lesser distance than the length of said metal strip between them to bow said metal strip away from said opposite surface of said formed sheet, and means for controlling said means for heating in response to changes in the bowing of said metal strip to cause heating of said formed sheet when the bowing of said metal strip is greater than a predetermined minimum extent, whereby when the temperature of said formed sheet is below a preset temperature it has lesser dimensions, said strip of metal is bowed away from said opposite surface of said formed sheet greater than said predetermined minimum extent and said means for controlling activates said means for heating; as said formed sheet is heated it expands thereby causing said metal strip to be less bowed and when the temperature of said formed sheet reaches said preset temperature said metal strip is bowed said predetermined minimum extent and said means for heating is deactivated.
Claim 5
Dependent Claim
89 words
The implement of claim 1 wherein said means for heating and said means for controlling said means for heating comprise an electrical heating circuit including electrical contact means supported from said opposite surface of said formed sheet and extending over said bowed strip of metal at a fixed operating distance from said opposite surface for closure by said strip of metal to complete said electrical heating circuit when said strip of metal is bowed away from said opposite surface of said formed sheet greater than said predetermined minimum extent.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-05 | 1976-09-04 | 1977-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-05 | 1980-09-04 | 1981-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-05 | 1984-09-04 | 1985-03-06 | $7700.00 | Window Closed / Lapsed |