US3681933A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Defrost control
Assignee: Dynamics Corp of America
•
Filing: 1970-08-20
•
Granted: 1972-08-08
•
Expires: 1990-08-20
Abstract
Abstract A defrost control for a refrigerator wherein first and second thermistors are mounted in conductive contact with the evaporator coil and a third thermistor is mounted so as to be responsive to the ambient temperature within the unit. Defrost is initiated when a predetermined relative value occurs indicating the temperature differential between the evaporator and the ambient temperature. The thermistor transmits signals to a logic section which controls a defrost relay. A third thermistor deactivates the relay at a predetermined evaporator temperature.
Inventors
- 👤 Frank T Check Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 05:06
CPC Classifications
F; F25; F25D; F25D21/00; F25D21/002; F25D21/006; F25B; F25B2700/00; F25B2700/21; F25B2700/2117; F25D2700/00; F25D2700/12
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
113 words
A defrost control for a refrigerating unit including an evaporating coil comprising defroster means, first and second thermistors mounted in conductive contact with said evaporator coil, and responsive to the temperature therein, a third thermistor mounted so as to be responsive to the ambient temperature with said unit, a voltage divider including said first and third thermistors, control means coupled to said voltage divider and responsive to a predetermined voltage level output of said voltage divider, relay means coupled to said defroster means and responsive to the output of said control means, and means coupling said third thermistor to said relay means for deenergizing said relay means at a predetermined evaporator coil temperature.
Claim 2
Dependent Claim
113 words
A defrost control for a refrigerating unit including an evaporating coil comprising defroster means, first and second thermistors mounted in conductive contact with said evaporator coil, and responsive to the temperature therein, a third thermistor mounted so as to be responsive to the ambient temperature with said unit, a voltage divider including said first and third thermistors, control means coupled to said voltage divider and responsive to a predetermined voltage level output of said voltage divider, relay means coupled to said defroster means and responsive to the output of said control means, and means coupling said third thermistor to said relay means for deenergizing said relay means at a predetermined evaporator coil temperature.
Claim 3
Dependent Claim
72 words
A defrost control for a single compartment refrigerating unit including an evaporating coil comprising means for detecting the absolute temperature of said evaporating coil, means for detecting the ambient temperature within said unit, defrosting means, means for actuating said defrost means in response to a predetermined temperature differential between the temperature of said evaporating coil and said ambient temperature, and means for deactuating said defrosting means at a predetermined evaporating coil temperature.
Claim 4
Dependent Claim
72 words
A defrost control for a single compartment refrigerating unit including an evaporating coil comprising means for detecting the absolute temperature of said evaporating coil, means for detecting the ambient temperature within said unit, defrosting means, means for actuating said defrost means in response to a predetermined temperature differential between the temperature of said evaporating coil and said ambient temperature, and means for deactuating said defrosting means at a predetermined evaporating coil temperature.
Claim 5
Dependent Claim
16 words
The control of claim 2 wherein said temperature detecting means comprise thermistors and associated electrical circuitry.
Claim 6
Dependent Claim
53 words
The control of claim 2 wherein said means for detecting the temperature of said evaporating coil and said means for detecting said ambient temperature comprise first and second thermistors connected in an electrical bridge, and said means for actuating said defrost means comprises a relay responsive to the voltage output of said bridge.
Claim 7
Dependent Claim
18 words
The control of claim 4 further comprising voltage level detecting means coupled between said bridge and said relay.
Claim 8
Dependent Claim
35 words
The control of claim 4 further comprising a third thermistor in conductive contact with said evaporating coil and coupled to said relay for deenergizing said relay when said evaporator coil rises above a predetermined temperature.
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) | 1975-08-08 | 1976-02-07 | 1976-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-08 | 1980-02-07 | 1980-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-08 | 1984-02-07 | 1984-08-08 | $7700.00 | Window Closed / Lapsed |