Patent US3760310A successfully refreshed from Google Patents.
US3760310A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermoferrite switch with ptc resistor temperature compensation
Assignee: Honeywell Inc
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Filing: 1972-05-11
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Granted: 1973-09-18
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Expires: 1992-05-11
Abstract
Abstract Disclosed are temperature responsive switches wherein a permanent magnet cooperates with a piece of thermoferrite (TF) to close or open contacts depending on whether the temperature of the TF is below or above its Curie point and hence is or is not attracted by the magnet. A positive temperature coefficient (PTC) resistor is connected electrically in series with the TF and is in intimate heat conducting relationship with it. The TF and PTC resistor are heated by passing current through them and the PTC resistor limits the ultimate temperature attained by greatly increasing its resistance as a predetermined upper limit temperature is attained.
Inventors
- 👤 K Carson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 22:09
CPC Classifications
H; H01; H01H; H01H37/00; H01H37/02; H01H37/64; H01H37/68; H01H37/32; H01H37/58; H01H61/00; H01H61/01; H01H61/013
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
80 words
A temperature responsive switch comprising: circuit controlling contact means; permanent magnet means attached to said contact means; thermally responsive magnetic means having states of magnetism or non-magnetism dependent upon temperature, said magnetic means being positioned in controlling relation to said permanent magnet means; and PTC resistor means connected in electrical series to said magnetic means for supplying heat thereto, whereby said magnetic means, dependent upon its magnetic state, attracts or releases said permanent magnet means to operate said contact means.
Claim 2
Dependent Claim
80 words
A temperature responsive switch comprising: circuit controlling contact means; permanent magnet means attached to said contact means; thermally responsive magnetic means having states of magnetism or non-magnetism dependent upon temperature, said magnetic means being positioned in controlling relation to said permanent magnet means; and PTC resistor means connected in electrical series to said magnetic means for supplying heat thereto, whereby said magnetic means, dependent upon its magnetic state, attracts or releases said permanent magnet means to operate said contact means.
Claim 3
Dependent Claim
58 words
A temperature responsive switch of claim 1 wherein said thermally responsive magnetic means comprises a Curie point temperature responsive thermoferrite which is magnetic when the temperature to which said thermoferrite is exposed is below said Curie point temperature and wherein said thermoferrite is non-magnetic when the temperature to which it is exposed is above said Curie point temperature.
Claim 4
Dependent Claim
35 words
The temperature responsive switch of claim 2 wherein said contact means comprises a normally open switch having first and second switch arms and wherein said permanent magnet means is fixed to one of said arms.
Claim 5
Dependent Claim
48 words
The temperature responsive switch of claim 1 wherein said contact means comprises a normally closed switch having a first switch arm and a second flexible switch arm and further comprising a spring bias reset button having said permanent magnet means affixed thereto for resetting said normally closed switch.
Claim 6
Dependent Claim
34 words
The temperature responsive switch of claim 4 wherein said thermally responsive magnetic means comprises a thermoferrite having a Curie point temperature below which said thermoferrite is magnetic and above which said thermoferrite is non-magnetic.
Claim 7
Dependent Claim
28 words
The temperature responsive switch of claim 5 wherein said thermoferrite and said PTC resistor means are so constructed to form a chip attached to said flexible switch arm.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-17 | 1977-03-19 | 1977-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-17 | 1981-03-19 | 1981-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-17 | 1985-03-19 | 1985-09-18 | $7700.00 | Window Closed / Lapsed |