US3796981A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fail safe thermostatic switch
Assignee: Kidde Inc
•
Filing: 1972-09-05
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Granted: 1974-03-12
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Expires: 1992-09-05
Abstract
Abstract Disclosed is a temperature responsive switch including a pair of contacts that open and close in response to temperature variations and are connected to lead wires by fusible coupling such as solder. In the event of contact overheating one or both of the fusible couplings melts and a bias spring separates the affected lead wire and contact, thus opening the switch.
Inventors
- 👤 E Poitras
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:24
CPC Classifications
H; H01; H01H; H01H71/00; H01H71/10; H01H71/12; H01H71/14; H01H71/20
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
112 words
A thermally responsive switch comprising: electrical contact means for opening and closing an electrical circuit; temperature responsive actuator means for opening and closing said contact means in response to temperature transitions spanning a preselected contact temperature; lead means for connecting said contact means to an electrical circuit; fusible coupling means connecting said lead means to said electrical contact means and exposed to the same ambient temperature therewith, said fusible coupling means adapted to melt at a preselected fuse temperature that is higher than said contact temperature; and separation means for insuring permanent separation of said lead means and said electrical contact means for producing disconnection therebetween when said fusible coupling means fuses.
Claim 2
Dependent Claim
112 words
A thermally responsive switch comprising: electrical contact means for opening and closing an electrical circuit; temperature responsive actuator means for opening and closing said contact means in response to temperature transitions spanning a preselected contact temperature; lead means for connecting said contact means to an electrical circuit; fusible coupling means connecting said lead means to said electrical contact means and exposed to the same ambient temperature therewith, said fusible coupling means adapted to melt at a preselected fuse temperature that is higher than said contact temperature; and separation means for insuring permanent separation of said lead means and said electrical contact means for producing disconnection therebetween when said fusible coupling means fuses.
Claim 3
Dependent Claim
38 words
A switch according to claim 1 wherein said separation means comprises bias means disposed so as to urge separation of said lead means and said electrical contact means for producing disconnection therebetween when said fusible coupling means fuses.
Claim 4
Dependent Claim
26 words
A switch according to claim 2 wherein said fusible coupling means is in thermal contact with said contact means and is responsive to the temperature thereof.
Claim 5
Dependent Claim
41 words
A switch according to claim 3 wherein said electrical contact means comprises a metal contact and said lead means comprises a lead wire and said fusible coupling means comprises a fusible metal for affixing said lead wire to said metal contact.
Claim 6
Dependent Claim
27 words
A switch according to claim 4 wherein said bias means comprises a spring for separating said lead wire from said metal contact when said fusible metal melts.
Claim 7
Dependent Claim
91 words
A switch according to claim 5 wherein said actuator means comprises a metal linear actuator with a given coefficient of thermal expansion and further comprises an arcuate metal member with a lower coefficient of thermal expansion that supports said metal contact, the ends of said arcuate member being secured to the ends of said linear actuator by attachment means and said metal contact being mounted on said arcuate member so as to move in a path substantially perpendicular to said linear actuator as the length thereof changes in response to temperature.
Claim 8
Dependent Claim
42 words
A switch according to claim 6 wherein said contact means comprises a second metal contact disposed to said substantially perpendicular path of said metal contact so as to be connected and disconnected therewith in response to changes in length of said actuator.
Claim 9
Dependent Claim
26 words
A switch according to claim 7 wherein said attachment means comprises adjustment means so that said preselected critical length and said preselected contact temperature are adjustable.
Claim 10
Dependent Claim
14 words
A switch according to claim 7 comprising casing means for enclosing the components thereof.
Claim 11
Dependent Claim
15 words
A switch according to claim 9 wherein said casing means comprises said linear actuator means.
Claim 12
Dependent Claim
61 words
A switch according to claim 7 wherein said lead means comprises a second lead wire and said fusible coupling means comprises a second fusible metal for affixing said second lead wire to said second metal contact and said bias means comprises a second spring for separating said second lead wire and said second metal contact when said second fusible metal melts.
Claim 13
Dependent Claim
39 words
A switch according to claim 11 comprising a second opposing arcuate member that is secured by said attachment means and wherein said second metal contact is mounted on said second arcuate member and travels in said substantially perpendicular path.
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) | 1977-03-11 | 1977-09-10 | 1978-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-11 | 1981-09-10 | 1982-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-11 | 1985-09-10 | 1986-03-12 | $7700.00 | Window Closed / Lapsed |