US3115017A - Defrosting system for refrigeration installation - Google Patents

Description

Dec. 24, 1963 E. J. KOCHER ETAL 3,115,017

DEFROSTING SYSTEM FDR REFRIGERATION INSTALLATION 2 Sheets-Sheet 1' Filed March 7, 1962 CONDENSER VER (I RECEI CONDENSER (I RECEIVER I) INVENTORS E. J. KOCHER y J. /V. LONG MM! 8% A-rranmsys 3,115,017 DEFROSTING SYSTEM FOR REFRIGERATION INSTALLATION Erich J. Kocher and Joseph N. Long, Milwaukee, Wis,

assignors to Vilter Manufacturing Corporation, Milwaukee, Wis., a corporation of Wisconsin Filed Mar. 7, 1962, Ser. No. 178,004 3 Claims. (Cl. 62155) The present invention relates generally to improvements in the art of defrosting refrigeration installations, and it relates more specifically to an improved system and apparatus for defrosting the evaporators or cooling coils of space cooling installations with the aid of warm The primary object of this invention is to provide a simple but highly effective system for periodically defrosting refrigerated space cooling installations.

The defrosting of refrigeration installations has heretofore been effected primarily with three well known systems, namely, the water defrost system; the electrical system; and the hot gas system. The primary objections to these prior systems have been as follows:

The water defrost system requires large quantities of Water, special water disposal facilities, costly plumbing, danger of freeze-up due to leaky valves, and danger of water pan overflow due to ice accumulation or the like.

The electrical defrost system is not only somewhat hazardous but requires expensive electric power wiring, control switches, and heaters.

The hot gas defrosting system generally requires extra refrigerant piping such as hot gas and liquid return lines,

hot gas valves and liquid relief valves, storage space for condensed liquid or boil oif equipment such as thermo banks or heat cells.

While the idea of utilizing Warm air for defrosting purposes has also been proposed in connection with individual household refrigerator cabinets, these prior proposals lacked suitable structure sufiicient to effectively apply the principles in larger commercial space coolers embodying one or more independent or segregated spaces to be cooled.

It is therefore an important object of the present invention to provide an improved system and apparatus for utilizing warm air to effect automatic and eflicient defrosting of one or more cooling areas or spaces in a dependable manner.

Another object of the invention is to provide an improved air cooling system and apparatus with an extremely simple and economical automatically operable warm air defrosting means which obviates the disadvantages heretofore attendant and other available defrosting systems.

Another object of my invention is to provide a novel and improved warm air defrosting system for a refrigeration plant by means of which defrosting is accomplished automatically by merely closing the refrigerant valves and adjusting a pair of dampers so that warm air from an adjacent non-refrigerated space is forced over and about the cooling coil until defrosting has been accomplished.

Still another object of my present invention is to provide a simple and improved defrosting system which is highly flexible and readily adaptable for use in defrosting either a single or a multiplicity of refrigerated spaces in a most efficient manner.

These and other objects and advantages of the present invention will become apparent from the following detailed description reference being made to the accompanying drawings in which:

PEG. 1 is a fragmentary vertical section through a single typical refrigerated space or cooler embodying the improved defrosting system with the refrigerating apparatus tes Patent 2 being diagrammatically illustrated and with the dampers being shown in position whereby the defrosting cycle is inactive;

FIG. 2 is a similar section but showing the dampers moved to a position wherein the defrosting cycle is effective;

FIG. 3 is a somewhat reduced horizontal section through adjacent coolers of a typical multiple refrigerator system diagrammatically illustrating the improved defrosting system applied to and utilized in conjunction with the several coolers or compartments;

FIG. 4 is a similarly reduced rear elevation of the multiple system of FIG. 2;

FIG. 5 is a typical wiring diagram providing for automatic operation of the multiple system of FIGS. 2 and 3.

While the improvements have been shown and described herein as being advantageously embodied in either a single or multiple unit cooling system having cooling units of a particular construction and in which the defrosting cycles are automatically controllable in a specific manner, it is not desired or intended to thereby unnecessarily limit or restrict the use and operation of the invention by reason of such specific illustration; and it is furthermore contemplated that the descriptive terminology used herein shall be given the broadest possible interpretation consistent with the disclosure.

Referring now to the drawings and particularly FIGS. 1 and 2 thereof, the refrigerated space or cooler is designated generally by the numeral 6, the walls 7 thereof being well insulated from the surrounding area in the usual manner. Access to the refrigerated space 6 is obtained through a door, not shown, and a compartment 8 within or immediately adjacent to the space 6 contains an open-ended casing 9 which houses the heat exchanger or cooling coils it) of the refrigerant circulating system. Refrigerant is supplied to and circulated through the cooling coil 10 by a motor driven compressor 11 which has its suction or inlet side communicating with one end of the coil 10 by way of the conduit 12 with its discharge or high pressure side communicating with the other end of the coil 10 via the usual condenser 13 and receiver 14 through the conduit 15 and expansion valve 19. In accordance with customary practice, a fan or blower 16 driven by a motor 16' is also housed in the casing 9 and is adapted to circulate air from within the space 6 through the end opening 17 of the casing 9 as indicated by the arrows in FIG. 1 and over the cooling coils 9 where the air is cooled and is then conducted through the casing opening 18 and back into the space 6. The system and apparatus thus far described is old and well-known with various means for periodically defrosting the cooling coils 9 having heretofore been employed.

In practicing the present invention, the ice accumulations which build up on the cooling coils 9 during operation of the re rigerating apparatus are periodically removed by ntilizing the relatively warm air from the space 20 outside of the insulated walls 7 which define the refrigerated space 6 for defrosting purposes. A motor driven fan or blower 21 is thus mounted in the warm space or room 20 adjacent the exterior of one of the walls 7 in proximity to the compartment 8, and the discharge side of the blower 21 is placed in communication with the interior of the casing 9 by means of a .warm air duct 22. terminating at 23 Within the casing 9 upstream of the coils 1t) and between these coils and the casing end opening 17. To provide for circulation of warm air over the cooling coils and entirely within the casing 9 as will hereinafter more fully appear, a return air duct 24 is provided, one end of the return air duct terminating at 25 downstream of the coils 16' and between these coils and a partition 26 provided with an opening 27 and located in the casing 9 somewhat in advance of the fan 16.

3 The return air duct leads to the space exteriorly of the refrigerated space or room, and a drain passage 28 located below the cooling coils 1t) communicates with the duct 24 to conduct defrost water thereto for disposal in an exteriorly located waste pipe 29 or the like.

During the refrigerating cycle, the ends 23, 25 of the ducts 22, 24 respectively are closed and the openings 17, 27 of the casing 9 are open. For this purpose, a pair of swingably mounted dampers 31, 32 respectively are provided, and these dampers are shown in their effective positions for the refrigerating cycle in FIG. 1 with damper 31 closing the end 23 of the warm air duct 22 and damper 32 closing the end 25 of the return air duct 24. Obviously, during the refrigerating cycle, the circulating fan 16 is in operation and the warm air blower 21 is off. When an excess of frost or ice has accumulated on the cooling coils 10, the dampers 31, 32 are swung to the positions shown in FIG. 2 to close the casing openings 17, 27 respectively and open the warm air duct 22 and the return air duct 24. For this purpose, a damper act-uating motor 33 or the like may be provided, the motor 33 being operatively coupled to the dampers 31, 32 by suitable actuating mechanism such as the levers 34, 35, 36 and the links 27, 38 shown. With the cooling coil section of the casing 9 thus sealed off from the refrigerated space by the dampers 31, 32 and with the ducts, 22, 24 open to the sealed area, the fan 16 is shut off and the blower 21 is turned on. Warm defrost air is thereby circulated through the duct 22 over and about the coils 19 and then exteriorly of the space 6 to exhaust, and the defrost water from the coils 10 is simultaneously conducted with the return air to exhaust via the drain 28 and duct 24. This operation continues until the coils 10 are sutficiently defrosted whereupon the dampers are returned to the positions shown in FIG. 1 and the blower 21 is turned off and fan 16 placed in operation.

As already indicated, the defrosting system thus shown and described is applicable either to a single refrigeration unit or to a multiple unit system as shown diagrammatically in FIGS. 3 and 4. In such a multiple unit system, each of the refrigerated spaces 6 is provided with one of the cooling units above described and comprising the casing 9 and the circulating fan 16 and cooling coils 10 housed therein. However, only a single warm air blower 21 need be provided for circulating warm defrost air through a main supply duct 4t) to each of the cooling units via their respective branch ducts 22, and the warm air and waste water is removed from each cooling unit through their respective return ducts 24 and drains 28 to a common return air and condensate duct 41. In such multiple system, the refrigeration cycle may likewise be effected by a single centrally located compressor, condenser and receiver.

The control of the refrigerating and defrosting systems may be performed in any desired manner either manually or automatically, and the wiring diagram shown in FIG. 5 typifies a control for the multiple unit system shown in FIGS. 3 and 4, such control also being readily applicable to a single unit system. In FIG. 5, the switches and timers are shown in their positions for the normal cooling cycle with each of the three loads being controllable by its respective temperature control to maintain the individual temperature desired for each unit. In this control system, a suitable thermostat 43 is located in each of the refrigerated spaces 6, and each thermostat is electrically connected to a suitable timer 44 set for timing the defrosting cycle. In addition, each room thermostat 43 is electrically coupled to a solenoid valve 45 controlling flow through the liquid refrigerant line 15 between the receiver 14 and coils 10, and each thermostat is additionally coupled to a solenoid valve 46 controlling flow through the suction line 12 between the coils 10 and compressor 11. Each timer 44 is electrically connected to its respective damper motor 33 which in turn throws a switch 47 controlling the respective cold air cir- 4 culating fans 16 through its motor 16, the switches 47 likewise controlling the operation of the warm air defrost blower 21 through its motor 21'.

Accordingly, when one thermostat 43 is satisfied, it will open the circuit to its respective liquid and suction solenoid valves 45, 46, respectively, thus stopping the circulation of refrigerant. Periodically at preset times, the defrost timer 44 through a double-throw switch therein will also stop the refrigerant circulation by disconnecting the thermostat 43 and solenoid valves 45, 46 and the position of the damper motor 33 will be reversed. At the first movement of the damper motor 33, the end switch attached to its shaft breaks the circuit to the fan motor 16 to stop the cool air circulating fan 16. As the damper motor 33 approaches the opposite end of travel, the end switch on its shaft closes the circuit to start the defrosting blower motor 21 and thereby operate the blower 21. During operation of the motor 21, the dampers 31, 32 are in the position shown in FIG. 2 so that warm defrost air is circulated through the ducts 22, 24 and over the cooling coils 10. At the end of the defrost period, the timer 44 reverses the position of its single-pole, double-throw switch which runs the damper motor 33 back to its original position. At this time, the liquid and suction valves 45, 46 are also opened to restore refrigeration, and as soon as the damper motor 33 starts to move, the end switch on its shaft stops the defrosting blower 21. As the dampers 31, 32 approach the positions shown in FIG. 1, the fan motor 16 is restarted to operate the cool air circulating fan 16. It should be understood that one defrosting blower may be used for all of the air units as above indicated, and the end switch on the shaft of each of the damper motors 33 will start the blower 21 whenever defrosting is required. It is, of course, preferable to set the defrosting timers so as to defrost the several units at staggered intervals whenever this control system is used in a multiple unit system.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

We claim:

1. In a refrigerator defrosting system, means providing an enclosed space to be refrigerated, a housing having open ends and located within said space, a refrigerant air cooling coil confined within said housing, a refrigerant supply means, valve means for normally connecting said refrigerant supply means to said coil, a fan for normally circulating air from said space through said housing in contact with said coil and back to said space, means for periodically interrupting the delivery of refrigerant to said coil by said valve means and for simultaneously arresting operation of said fan, means for sealing the interior of said housing on both sides of said coil from said space during such periods of interruption and for simultaneously placing the interior of said housing in communication with the atmosphere exterior of said enclosed space, and a blower for circulating warm air from the exterior through said sealed housing portion in contact with said coil and back to the exterior whenever said refrigerant delivery and fan operation is interrupted.

2. In a refrigerator defrosting system, means providing an enclosed space to be refrigerated, a housing having open ends and located within said space, a refrigerant air cooling coil confined within said'housing, means forming passageways extending from the atmosphere exterior of said space to opposite sides of said coil within said housing, means normally closing said passageways to seal the interior of said housing from the exterior atmosphere, a refrigerant supply means, valve means for normally connecting said refrigerant supply means to said coil, a fan for normally circulating air from said space through said housing in contact with said coil and back to said space, means for periodically interrupting the delivery of refrigerant to said coil by said valve means and for simultaneously arresting operation of said fan, means for actuating said closure means to open said passageways and simultaneously seal the interior of said housing on both sides of said coil from said space during such periods of interruption, and a blower for circulating warm air from the exterior through said sealed housing portion in contact with said coil and back to the exterior whenever said refrigerant delivery and fan operation is interrupted.

3. In a refrigerator defrosting system, means providing an enclosed space to be refrigerated, a housing having open ends and located within said space, a refrigerant air cooling coil confined within a medial portion of said housing between the open ends thereof, means forming passageways extending from the atmosphere exterior of said space to opposite sides of said coil within said housing, a pair of swingably mounted dampers normally closing said passageways to seal the interior of said housing from the exterior atmosphere, a refrigerant supply means, valve means for normally connecting said refrigerant supply means to said coil, a fan for normally circulating air from said space through said housing in contact with said coil and back to said space, means for periodically interrupting the delivery of refrigerant to said coil by said valve means and for simultaneously arresting operation of said fan, means for simultaneously swinging said dampers to open said passageways and simultaneously seal the interior of said housing on both sides of said coil beyond said passageways from said space during such periods of interruption, and a blower for circulating warm atmospheric air from the exterior only through said sealed housing portion and in contact with said coil and then back to the exterior whenever said refrigerant delivery and fan operation is interrupted.

References Cited in the file of this patent UNITED STATES PATENTS 2,525,868 Corhanidis Oct. 17, 1950 2,896,425 Dunbar July 28, 1959 2,939,295 Robson June 7, 1960 3,004,400 Mann et al. Oct. 17, 1961 3,028,734 Weinstein Apr. 10, 1962

Claims (1)

1. IN A REFRIGERATOR DEFROSTING SYSTEM, MEANS PROVIDING AN ENCLOSED SPACE TO BE REFRIGERATED, A HOUSING HAVING OPEN ENDS AND LOCATED WITHIN SAID SPACE, A REFRIGERANT AIR COOLING COIL CONFINED WITHIN SAID HOUSING, A REFRIGERANT SUPPLY MEANS, VALVE MEANS FOR NORMALLY CONNECTING SAID REFRIGERANT SUPPLY MEANS TO SAID COIL, A FAN FOR NORMALLY CIRCULATING AIR FROM SAID SPACE THROUGH SAID HOUSING IN CONTACT WITH SAID COIL AND BACK TO SAID SPACE, MEANS FOR PERIODICALLY INTERRUPTING THE DELIVERY OF REFRIGERANT TO SAID COIL BY SAID VALVE MEANS AND FOR SIMULTANEOUSLY ARRESTING OPERATION OF SAID FAN, MEANS FOR SEALING THE INTERIOR OF SAID HOUSING ON BOTH SIDES OF SAID COIL FROM SAID SPACE DURING SUCH PERIODS OF INTERRUPTION AND FOR SIMULTANEOUSLY PLACING THE INTERIOR OF SAID HOUSING IN COMMUNICATION WITH THE ATMOSPHERE EXTERIOR OF SAID ENCLOSED SPACE, AND A BLOWER FOR CIRCULATING WARM AIR FROM THE EXTERIOR THROUGH SAID SEALED HOUSING PORTION IN CONTACT WITH SAID COIL AND BACK TO THE EXTERIOR WHENEVER SAID REFRIGERANT DELIVERY AND FAN OPERATION IS INTERRUPTED.

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