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Patent US3781737A successfully refreshed from Google Patents.
US3781737A
Expired / Lapsed
US
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Thermal circuit protector
Assignee: Emerson Electric Co
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Filing: 1973-02-20
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Granted: 1973-12-25
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Expires: 1993-02-20
Abstract
Abstract A thermal circuit protector for automatically opening a circuit when the ambient temperature becomes too high. The protector comprises a fusible pellet disposed inside a conductive case. A first conductor electrically contacts the case while a second conductor is electrically insulated from the case. Contact is made from the first conductor to the second by three electrically conductive balls which contact the case and the second conductor. A first spring maintains the electrical contact between the case, the balls and the second conductor. A second spring acts to break the contact between the case, the balls and the second conductor when the fusible pellet melts.
Inventors
- 👤 W Henry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 19:48
CPC Classifications
H; H01; H01H; H01H1/00; H01H1/12; H01H1/14; H01H1/16; H01H37/00; H01H37/74; H01H37/76; H01H37/764; H01H37/765
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
106 words
A thermal circuit protector which comprises: a tubular, electrically and thermally conductive case; a normally solid fusible pellet occupying one end of said case; an insulating plug occupying the other end of said case having a bore extending therethrough; a first conductor electrically contacting said case; a second conductor extending through the bore of said insulating plug; electrically conductive balls normally in electrical contact with the inside of said case and said second conductor; and spring means for maintaining said balls in electrical contact with said case and said second conductor when said pellet is solid and for breaking said electrical contact when said pellet melts.
Claim 2
Dependent Claim
106 words
A thermal circuit protector which comprises: a tubular, electrically and thermally conductive case; a normally solid fusible pellet occupying one end of said case; an insulating plug occupying the other end of said case having a bore extending therethrough; a first conductor electrically contacting said case; a second conductor extending through the bore of said insulating plug; electrically conductive balls normally in electrical contact with the inside of said case and said second conductor; and spring means for maintaining said balls in electrical contact with said case and said second conductor when said pellet is solid and for breaking said electrical contact when said pellet melts.
Claim 3
Dependent Claim
80 words
The thermal circuit protector as claimed in claim 1, wherein said spring means comprises: a pressure spring exerting a first force on said conductive balls; and a release spring exerting a second force on said conductive balls, said second force opposing said first force, said second force being smaller than said first force when said pellet is solid, said second force being larger than said first force after said pellet melts to disengage said conductive balls and said second conductor.
Claim 4
Dependent Claim
23 words
The thermal circuit protector as claimed in claim 2, wherein an insulating member is disposed between said conductive balls and said release spring.
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) | 1976-12-24 | 1977-06-25 | 1977-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-24 | 1981-06-25 | 1981-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-24 | 1985-06-25 | 1985-12-25 | $7700.00 | Window Closed / Lapsed |