US3894404A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hot gas defrost refrigeration system
Assignee: Honeywell Inc
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Filing: 1974-07-29
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Granted: 1975-07-15
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Expires: 1994-07-29
Abstract
Abstract A control system for controlling the individual defrosting of a plurality of evaporators connected to a common refrigeration system wherein the defrosting is accomplished by the use of hot gas from the refrigeration system. The need for defrosting of a particular evaporator is called for either on demand by a frost sensor associated with the evaporator or by time by a time control. A sequential control apparatus is used to schedule the defrosting operation of the evaporators when they are defrosted on demand to limit the number of evaporators that are being defrosted at any particular moment as a limited amount of hot gas is available from the refrigeration system.
Inventors
- 👤 David J Stanton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:05
CPC Classifications
F; F25; F25B; F25B47/00; F25B47/02; F25B47/022; F25B5/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
266 words
In a control system for controlling the individual defrosting of at least one of a plurality of evaporators connected to a compressor system wherein the defrosting is accomplished by the use of hot gas from the compressor system, frost sensor means adapted to be connected to each of at least two of a plurality of evaporators of the refrigeration system for providing an output signal upon the need of defrosting of one of the evaporators, sequential control means having a plurality of output circuits for scanning and for individually initiating a defrost cycle of any one of the two evaporators which needs defrosting, a plurality of relay means each having two input circuits and an output circuit, said relay means is energized when each of said input circuits receive input signals, and circuit means connecting said output signal of each of said frost sensor means to one input of a respective relay means and one of said output circuits of said sequential control means to a second input of said relay means whereby upon a frost sensor means of one evaporator having an output to demand defrost, said relay means is energized when said sequential control means provides a signal to said relay means, said output of each of said relay means being adapted to control valve means in the compressor system to provide a hot gas defrosting operation for one of the evaporators at a time depending upon a demand for defrosting operation by said frost sensor means and said signal of said sequential control means while normal operation of the other evaporator is maintained.
Claim 2
Dependent Claim
266 words
In a control system for controlling the individual defrosting of at least one of a plurality of evaporators connected to a compressor system wherein the defrosting is accomplished by the use of hot gas from the compressor system, frost sensor means adapted to be connected to each of at least two of a plurality of evaporators of the refrigeration system for providing an output signal upon the need of defrosting of one of the evaporators, sequential control means having a plurality of output circuits for scanning and for individually initiating a defrost cycle of any one of the two evaporators which needs defrosting, a plurality of relay means each having two input circuits and an output circuit, said relay means is energized when each of said input circuits receive input signals, and circuit means connecting said output signal of each of said frost sensor means to one input of a respective relay means and one of said output circuits of said sequential control means to a second input of said relay means whereby upon a frost sensor means of one evaporator having an output to demand defrost, said relay means is energized when said sequential control means provides a signal to said relay means, said output of each of said relay means being adapted to control valve means in the compressor system to provide a hot gas defrosting operation for one of the evaporators at a time depending upon a demand for defrosting operation by said frost sensor means and said signal of said sequential control means while normal operation of the other evaporator is maintained.
Claim 3
Dependent Claim
45 words
The invention of claim 1 wherein each of said relay means has a second output circuit connected to said sequential control means to inhibit other outputs on said output circuits of said sequential control means until a defrosting operation for the one evaporator is completed.
Claim 4
Dependent Claim
44 words
The invention of claim 1 comprising input circuit means connected to said sequential control means adapted to receive an input from a timer means controlling the defrosting operation of other evaporators to inhibit said sequential control means when a time defrost operation is initiated.
Claim 5
Dependent Claim
90 words
The invention of claim 1 wheRein said output circuit of said relay means is adapted to close a refrigeration solenoid valve and open a hot gas solenoid valve when a defrosting operation is needed and comprising time delay means connected in said output circuit so that upon a termination of the defrosting operation said relay means is adapted to close the hot gas solenoid, and after a predetermined time to allow for the evaporator to drip free of water, said relay means is adapted to open the refrigeration solenoid valve.
Claim 6
Dependent Claim
25 words
The invention of claim 1 wherein said sequential control means is a BCD to decimal converter circuit for sequentially providing outputs on said output circuits.
Claim 7
Dependent Claim
46 words
The invention of claim 3 wherein each of said relay means has a second output connected to said sequential control means to maintain a demand defrost operation already initiated even though said input circuit of said sequential control means has an input from the timer means.
Claim 8
Dependent Claim
214 words
In a control system for controlling a selective demand defrost operation of individual sets of evaporators connected to a refrigeration system by furnishing hot gas to a particular set of evaporators a plurality of frost responsive means adapted to be connected to respond to the need of a defrosting operation of individual sets of evaporators, sequential control means having a plurality of output circuits upon which an individual output is provided in a sequential operation manner, a plurality of relay means each of which is adapted to control the delivery of hot gas to one set of evaporators, circuit means connecting each of frost responsive means for one set of evaporators to one of said relay means and one of said output circuits of said sequential control means to said one relay means, whereby upon said first responsive means of a set of evaporators providing an output said relay means is energized when said sequential control means output is available, and circuit means connected between each of said relay means and said sequential control means to inhibit said sequential operation once a defrosting operation of a particular set of evaporators is started until said relay means is de-energized at which time said sequential control operates in a sequential manner to the next relay means.
Claim 9
Dependent Claim
214 words
In a control system for controlling a selective demand defrost operation of individual sets of evaporators connected to a refrigeration system by furnishing hot gas to a particular set of evaporators a plurality of frost responsive means adapted to be connected to respond to the need of a defrosting operation of individual sets of evaporators, sequential control means having a plurality of output circuits upon which an individual output is provided in a sequential operation manner, a plurality of relay means each of which is adapted to control the delivery of hot gas to one set of evaporators, circuit means connecting each of frost responsive means for one set of evaporators to one of said relay means and one of said output circuits of said sequential control means to said one relay means, whereby upon said first responsive means of a set of evaporators providing an output said relay means is energized when said sequential control means output is available, and circuit means connected between each of said relay means and said sequential control means to inhibit said sequential operation once a defrosting operation of a particular set of evaporators is started until said relay means is de-energized at which time said sequential control operates in a sequential manner to the next relay means.
Claim 10
Dependent Claim
75 words
The invention of claim 7 wherein said sequential control means has an input circuit adapted to be connected to a timer control for controlling the time controlled defrosting operation of other evaporators connected to the compressor system, said input circuit upon receiving an input signal, indicative of a time controlled defrost operation taking place, inhibits the sequential operation of said sequential control means to stop any further demand defrost operation of other sets of evaporators.
References Cited (Backward Citations)
US3316731A
Cited
US3638444A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-07-14 | 1979-01-13 | 1979-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-14 | 1983-01-13 | 1983-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-14 | 1987-01-13 | 1987-07-15 | $7700.00 | Window Closed / Lapsed |