US3845637A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Defrost cycle initiation system
Assignee: Texas Instruments Inc
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Filing: 1973-09-06
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Granted: 1974-11-05
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Expires: 1993-09-06
Abstract
Abstract A defrost cycle initiation system for refrigeration apparatus (e.g., a refrigerator, a refrigerator-freezer, or a room air conditioner) in which operation of the defrost system is initiated by frost build-up on the refrigeration apparatus. Generally, the refrigeration apparatus has cooling means for absorbing heat from a refrigerated zone, this cooling means being subject to the build-up of frost. The refrigeration apparatus has a main flow path for the intake of air from the refrigerated zone and for passage of the air over the cooling means to chill the air, and for discharge of the chilled air into the refrigerated zone, and a blower for forcing air through the main flow path. The defrost cycle initiation system of this invention includes an auxiliary flow path providing communication between the main flow path and the refrigerated zone, air normally flowing in the auxiliary flow path from the refrigerated zone to the main flow path when the refrigeration apparatus is in its normal mode of operation. The system further includes means for sensing the temperature of air flowing through the auxiliary flow path. The sensing means initiates a defrost cycle upon sensing a predetermined initiation temperature of air. Means are also provided for effecting reversal of flow of air in the auxiliary flow path in response to build-up of frost on the cooling means thereby to direct air having a temperature less than the abovementioned predetermined initiation temperature through the auxiliary flow path to lower the temperature of the air sensed by the sensing means below the predetermined temperature and for reestablishing the flow of air in the auxiliary flow path from the refrigerated zone to the main flow path upon the clearing of the cooling means of frost.
Inventors
- 👤 G Shepherd
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 08:47
CPC Classifications
F; F25; F25D; F25D17/00; F25D17/04; F25D17/06; F25D17/062; F25D17/065; F25D21/00; F25D21/002; F25D21/02; F25D2317/00; F25D2317/06; F25D2317/067; F25D2400/00; F25D2400/04
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
240 words
A defrost cycle initiation system for refrigeration apparatus having cooling means for absorbing heat from a refrigerated zone, said cooling means being subject to frost build-up, said refrigeration apparatus having a main flow path for the intake of air from said refrigerated zone, for passage of the air over said cooling means to chill the air and for the discharge of the chilled air into the refrigerated zone, and a blower for forcing the air through said main flow path; said system comprising an auxiliary flow path providing communication between said main flow path and said refrigerated zone, air normally flowing in said auxiliary flow path from said refrigerated zone to said main flow path when said refrigeration apparatus is in its normal mode of operation, means for sensing the temperature of air flowing through said auxiliary flow path adapted to initiate a defrost cycle upon sensing a predetermined initiation temperature of air, and means for effecting a reversal of flow of air in said auxiliary path in response to build-up of frost on said cooling means there-by to direct air having a temperature less than said predetermined initiation temperature through said auxiliary flow path to lower the temperature of the air sensed by the sensing means below said predetermined initiation temperature and for reestablishing the flow of air in said auxiliary flow path from said refrigerated zone to said main flow path upon clearing the cooling means of frost.
Claim 2
Dependent Claim
240 words
A defrost cycle initiation system for refrigeration apparatus having cooling means for absorbing heat from a refrigerated zone, said cooling means being subject to frost build-up, said refrigeration apparatus having a main flow path for the intake of air from said refrigerated zone, for passage of the air over said cooling means to chill the air and for the discharge of the chilled air into the refrigerated zone, and a blower for forcing the air through said main flow path; said system comprising an auxiliary flow path providing communication between said main flow path and said refrigerated zone, air normally flowing in said auxiliary flow path from said refrigerated zone to said main flow path when said refrigeration apparatus is in its normal mode of operation, means for sensing the temperature of air flowing through said auxiliary flow path adapted to initiate a defrost cycle upon sensing a predetermined initiation temperature of air, and means for effecting a reversal of flow of air in said auxiliary path in response to build-up of frost on said cooling means there-by to direct air having a temperature less than said predetermined initiation temperature through said auxiliary flow path to lower the temperature of the air sensed by the sensing means below said predetermined initiation temperature and for reestablishing the flow of air in said auxiliary flow path from said refrigerated zone to said main flow path upon clearing the cooling means of frost.
Claim 3
Dependent Claim
279 words
A defrost cycle initiation system as set forth in claim 1 wherein said refrigeration apparatus is a refrigerated unit, such as a refrigerator or the like, said refrigerated zone is a refrigerated compartment and said cooling means is an evaporator, said main flow path being in communication with said refrigerated zone and said evaporator being located in said main flow path so that air from said refrigerated compartment enters said main flow path, passes over said evaporator for being chilled, and is discharged into the refrigerated compartment, said auxiliary flow path being in communication with the refrigerated compartment for the intake of air from the refrigerated compartment and for the discharge of compartment air into the main flow path on the upstream and downstream side of the evaporator when the evaporator is substantially free of frost, said auxiliary flow path providing communication between the main flow path on the upstream side of the evaporator and the main flow path on the downstream side of the evaporator for the intake of air from the main flow path on the upstream side of the evaporator and for the discharge of said air from the main flow path back into the main flow path on the downstream side of the evaporator when the evaporator is at least partially blocked by frost, the temperature of said air from the main flow path on the upstream side of the evaporator being below said predetermined initiation temperature when said evaporator is at least partially blocked by frost, thereby to actuate said sensing means upon said air from the upstream side of said evaporator flowing through the auxiliary flow path and to initiate a defrost cycle.
Claim 4
Dependent Claim
180 words
A defrost cycle initiation system as set forth in claim 2 wherein said refrigerated unit is a refrigerator-freezer having a food compartment and a freezer compartment, said food and freezer compartments constituting said refrigerated zone, said freezer compartment being maintained at a colder temperature than said food compartment, said main flow path being in communication with the food compartment and the freezer compartment for the intake of air from both said compartments, said auxiliary flow path being in communication with said food compartment so that with the evaporator substantially free of frost said blower means draws in relatively warm air from said food compartment into the auxiliary flow path for discharge of this food compartment air into the main flow path on the upstream and downstream side of the evaporator, and upon build-up of frost on the evaporator said blower draws air from the main flow path on the upstream side of the evaporator into said auxiliary flow path for flowing over said sensing means thereby to cold-bias the latter below said predetermined initiation temperature and initiate a defrost cycle.
Claim 5
Dependent Claim
47 words
A defrost cycle initiation system as set forth in claim 3 wherein said refrigerator-freezer has a defrost heater located adjacent said evaporator, said heater, upon energization thereof, clearing said evaporator of frost, said heater being energized by said sensing means thereby to clear said evaporator of frost.
Claim 6
Dependent Claim
94 words
A defrost cycle initiation system as set forth in claim 4 wherein said refrigerator-freezer has a compressor and a cold control thermostat for energization and deenergization of said compressor there-by to regulate the temperature of the refrigerated zone, said sensing means comprising a thermostatic switch, said cold control thermostat and said thermostatic switch adapted to energize said heater upon said thermostatic switch sensing said predetermined initiation temperature and said cold control thermostat sensing a desired temperature in said food compartment, said thermostatic switch adapted to reset in a preselected time to deenergize said heater.
Claim 7
Dependent Claim
194 words
A defrost cycle initiation system as set forth in claim 1 wherein said refrigeration apparatus is an air conditioner, said refrigerated zone is a room which is to be cooled, and said cooling means is an evaporator, said auxiliary flow path being in communication with the room for the intake of room air and for the discharge of this room air into the main flow path on the upstream and downstream side of the evaporator when the evaporator is substantially frEe of frost build-up and for the intake of air from said main flow path on the upstream side of the evaporator and for discharge of said air from the main flow path back into the main flow path on the downstream of the evaporator when the evaporator is at least partially blocked by frost build-up, the temperature of said air from the main flow path on the upstream side of the evaporator being cooled by the at least partially blocked evaporator to a temperature below room temperature whereby said flow of air from the upstream side of the evaporator through said auxiliary flow path actuating said sensing means and initiating said defrost cycle.
Claim 8
Dependent Claim
184 words
A defrost cycle initiation system as set forth in claim 6 wherein said air conditioner has a main inlet for intake of room air into said main flow path and an auxiliary air inlet for intake of room air into the auxiliary flow path, an enclosure housing said sensing means, said enclosure constituting a portion of said auxiliary flow path, a first opening in said enclosure providing communication between said housing and said main flow path on the upstream side of said evaporator and a second opening in said enclosure in communication with said main flow path on the downstream side of the evaporator, whereby with said evaporator substantially free of frost, room air enters said enclosure via said auxiliary inlet and at least part of said room air entering said enclosure is discharged into said main flow path via said first opening and whereby upon frost accumulating on said evaporator, air is drawn into said enclosure from said main flow path via said first opening, said air from said main flow path drawn into the first opening being chilled below said room temperature.
Claim 9
Dependent Claim
88 words
A defrost cycle initiation system as set forth in claim 7 wherein said first opening is adjacent a portion of said evaporator whereby upon said flow of air in said main flow path through the evaporator becoming at least partially restricted by the build-up of frost on the evaporator, said flow of air from the main flow path on the upstream side of the evaporator into the enclosure via said first opening is chilled by said evaporator thereby to cold-bias said sensing means to initiate a defrost cycle.
Claim 10
Dependent Claim
174 words
A defrost cycle initiation system as set forth in claim 8 wherein said evaporator is a coiled refrigerant line having a plurality of end turns, said apparatus including a compartment enclosing said end turns of the evaporator, said end turn compartment being in communication with said main flow path on the upstream side of the evaporator and being in communication with the enclosure via said first opening whereby with said evaporator substantially free of frost build-up at least part of said air flows from said auxiliary air inlet into said main flow path on the upstream side of the evaporator via said enclosure and said end turn compartment, and with said evaporator at least partially blocked by frost, the flow of air in said auxiliary flow path is reversed so that air from the main flow path on the upstream side of the evaporator enters the end turn compartment thereby to be chilled by the evaporator end turns and then enters said enclosure thereby to cold-bias said sensing means and initiate a defrost cycle.
Claim 11
Dependent Claim
119 words
A defrost cycle system as set forth in claim 7 wherein said air conditioner includes a compressor and wherein said sensing means is a bimetal thermostat, said thermostat being operable to initiate operation of said compressor upon sensing air at a first predetermined temperature and to terminate operation of the compressor upon sensing air at a second and lower predetermined temperature, whereby with said evaporator substantially free of frost and with said thermostat sensing the room air temperature said thermostat initiating operation of the compressor upon the temperature of the room air rising to said first predetermined temperature and said thermostat terminating operation of said compressor upon the temperature of the room air dropping to Said second predetermined temperature.
Claim 12
Dependent Claim
155 words
A defrost cycle initiation system as set forth in claim 1 wherein said refrigeration apparatus includes a refrigeration system comprising a compressor and an evaporator, the latter constituting said cooling means, said sensing means being operable to initiate operation of the compressor upon sensing a first predetermined temperature and to terminate operation of the compressor upon sensing a second and lower predetermined temperature, whereby with said evaporator substantially clear of frost the temperature sensing means senses the temperature of air from the refrigerated zone so that upon the temperature of the air in the refrigerated zone rising to said first predetermined temperature said sensing means initiates operation of the compressor, and upon the temperature of the air in the refrigerated zone falling to said second predetermined temperature said sensing means terminates operation of the compressor and thus maintains the temperature of the air in the refrigerated zone between said compressor start and compressor stop temperatures.
Claim 13
Dependent Claim
29 words
A defrost cycle initiation system as set forth in claim 11 wherein said refrigeration apparatus is a room air conditioner and said temperature sensing means is a bimetal thermostat.
Claim 14
Dependent Claim
29 words
A defrost cycle initiation system as set forth in claim 1 wherein said refrigeration apparatus is a room air conditioner and said temperature sensing means is a bimetal thermostat.
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) | 1977-11-04 | 1978-05-06 | 1978-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-04 | 1982-05-06 | 1982-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-04 | 1986-05-06 | 1986-11-05 | $7700.00 | Window Closed / Lapsed |