US2741098A

US2741098A - Two temperature refrigerator

Info

Publication number: US2741098A
Application number: US503760A
Authority: US
Inventors: Alfred G Janos
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1955-04-25
Filing date: 1955-04-25
Publication date: 1956-04-10
Anticipated expiration: 1973-04-10

Description

April 10, 1956 A. G. JANOS TWO TEMPERATURE REFRIGERATOR Filed April 2, 1955 INVENTOR.

ALFRED G. JANOS HIS ATTORNEY United States Patent TWO TEMPERATURE REFRIGERATOR Alfred G. Janos, Louisville, Ky., assignor to General Electric Company, a corporation of New York Application April 25, 1955, Serial No. 503,760

4 Claims. (Cl. 62-4) The present invention relates to a two-temperature refrigerator and more particularly to an improved evaporator arrangement for maintaining both refrigerator compartments at the desired operating temperatures.

Most of the present day household refrigerators comprise both a fresh food storage compartment and a freezer compartment. In those refrigerators of the single evaporator type, the freezer compartment is normally positioned within the fresh food storage compartment and the single evaporator is disposed in direct heat exchange relationship with the walls defining the freezer compartment to maintain sub-freezing temperatures within the freezer compartment. In a second form of two-temperature refrigerator, separate evaporators are provided for the food storage compartment and the freezer compartment. The advantage of this arrangement is that only the freezer compartment evaporator need be designed to continuously maintain sub-freezing temperatures. During the operation of either type of refrigerator moisture from the air within the refrigerator cabinet collects on the evaporator surface in the form of frost when they are below freezing and if this frost layer is allowed to remain on the surfaces, it will actually decrease the efficiency of the refrigerating unit. In order to avoid the necessity for manually defrosting the evaporator surfaces, various schemes have been proposed and used to obtain the automatic defrosting thereof. A simple arrangement for defrosting an evaporator serving only a fresh food storage compartment comprises operating the evaporator within a range of temperatures such that during the idle period of the refrigerating unit, the evaporator rises to a sufiiciently high temperature to effect melting of all the frost collected thereon during the operating period of the unit. This scheme, while completely satisfactory for the defrosting of the fresh food compartment evaporator, cannot readily be employed for the automatic defrosting of an evaporator in contact with the walls of the freezer compartment. Operation of the freezer compartment evaporator for any substantial period of time at frost melting temperatures would also result in the melting of and damage to the frozen food contents of the freezer compartment. Automatic devices for defrosting freezer evaporators have included various means for supplying sufiicient heat to the freezer evaporator that the frost melts in a relatively short period of time and before any substantial thawing of the frozen foods results. These arrangements have been rather complicated and expensive particularly as compared with the relatively simple and inexpensive means and methods available for defrosting evaporators employed to cool only the food storage compartments.

An evaporator arrangement designed to refrigerate both the food storage compartment and the freezer compartment and one which can be automatically defrosted in the same manner as that employed for defrosting evaporators serving only the food storage compartment is described and claimed in the co-pending application of Harley H. Bixler, S. N. 503,606, filed concurrently herewith and assigned to the same assignee as the present invention. The evapora- 'ice tor which forms the invention of Harley H. Bixler is of the flooded recirculating type in which the refrigerating element or coil comprises two portions, one of which is positioned within the fresh food compartment and the second of which is positioned outside both the fresh food compartment and the freezer compartment. Means are provided for periodically circulating air from the freezer compartment over the second evaporator portion and back into the freezer compartment to maintain the contents thereof at sub-freezing temperatures. The automatic defrosting of the evaporator is obtained by natural circulation of warmed refrigerant from the fresh food evaporator portion to the freezer evaporator portion during each off-cycle of the refrigerating unit. In order to obtain satisfactory defrosting of both portions of the evaporator it is necessary that liquid refrigerant be present in the two portions during the defrosting or idle period of the refrigerating unit. It is an object of the present invention to provide an improved evaporator arrangement for refrigerating both compartments of a two-temperature refrigerator which does not require the presence of liquid refrigerant in the evaporator or the circulation thereof to obtain defrosting of the evaporator surface when the refrigerating unit is idle.

A further object of the invention is to provide a simple and inexpensive automatically defrosting evaporator which may be of the dry or non-recirculating type, arranged for the refrigeration of both compartments of a twotemperature refrigerator.

A further object of the invention is to provide a simple and inexpensive single evaporator disposed entirely Within the fresh food storage compartment and arranged to refrigerate both this compartment and a separate freezer compartment.

Further objects and advantages of the invention will become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of the specification.

In carrying out the objects of the present invention, there is provided a cabinet comprising an insulating partition dividing the cabinet into a freezer compartment and a fresh food compartment. A plate-type evaporator is disposed within the fresh food compartment in spaced relationship with the top wall of the compartment liner and with its peripheral edges in sealing engagement with the vertical compartment walls. The air within the fresh food compartment is cooled as a result of the natural circulation of this air into contact with the bottom surface of the plate-type evaporator while the freezer compartment is refrigerated by forced air recirculating means arranged to pass freezer compartment air through the space between the top liner wall and the fresh food compartment and into contact with the upper surface of the evaporator. As the evaporator is disposed entirely of the food storage compartment and out of contact with the freezer compartment, the evaporator can be periodically raised to defrosting temperatures without disturbing the contents of the freezer compartment.

For a better understanding of the present invention, reference may be had to the accompanying drawing in which the single figure is a side elevational view partially in section of a portion of a refrigerator including an embodiment of the invention.

Referring now to the drawing, there is shown a refrigerator including an outer metal Wall 1, an inner liner 2 delining a food storage compartment 3 and an inner liner 4 forming a freezer compartment 5. The spaces between the outer wall or shell 1 and the liners 2 and 4 are filled with suitable heat insulation 6 while the freezer compartment is insulated from the storage compartment 3 by means of the insulating partition 7. Access to the interior of the cabinet is obtained through an access opening 8 closed by an insulating door 9. A second inner door 16 closes the access opening to the freezer compartment? 5.

The liner 2 includes a top wall 11 which is preferably formed to slope downwardly from the front to the rear of the food storage compartment 3 and includes a depending portion or flange 12 at the forward end thereof having an interior surface portion 13 forming a short front wall section for the food storage compartment 3. The liner 2 also comprises two side walls 14, only one of which. is shown, and the rear wall 15..

.Means for coolingor refrigerating both the food storage. compartment 3 and the freezer compartment 5 *areuprovided in the form of a plate-type evaporator .16- positioned in the upper portion of the food storage compart-- merit 3 in spaced relationship with the top wall 11 of this compartment. The term,plate-type evaporator as used herein and in the appended claims is intended to cover any evaporator structure composed of a relatively large sheet or plate of imperforate construction. In the form. shown the evaporator comprises a sheet 17 and a serpentine evaporator tubing 18 afiixed toone side thereof. The side, rear, and forward edges of the platetype evaporator are preferablyin abutting or substantially sealing contact with the side walls 14, rear wall 15, and front wall 13 of the liner 2 so that the evaporator, the liner top wall 11, side walls 14 and front wall 13, form a'substantially closed duct or passageway.

Cooling of the food storage compartment '3 is 'obtained by the natural circulation of air upwardly along the front of this compartment into contact with the bottom surface of the plate-type evaporator and down the rear Wall 15. In accordance with the present invention the same evaporatoris also employed to maintain the freezer compartment at sub-freezing temperatures. The refrigeration of the freezer compartment 'S-is effected by the. forced circulation of air over the upper surface of the plate-type evaporator 16 forming the bottom of the passageway 20 and into the freezer compartment through an aperture 21 adjacent the freezer door 10. This circulation of air is obtained by means of the fan 23 positioned outside the rear wall 24 of the freezer compartment and driven by an electric motor 25. The fan 23 withdraws air from the freezer compartment through an aperture 26 and discharges this air through a conduit 27 the outlet end of which is connected to the rear end of the passageway .20. By this arrangement the air passing through the passageway '20 in contact withthe upper surface of the plate condenser 16 'is cooled to sub-freezing temperatures by contact with the evaporator surface before being discharged through theaperture 21 into the freezer compartment.

Liquid refrigerant is supplied to the evaporator 16 from refrigerant compressing and condensing apparatus including amotor driven compressor 30 and condensen31. Liquid refrigerant from the condenser 31 is introduced into the evaporator through the capillary tube 32 and vaporized refrigerant from the evaporator is withdrawn by the compressor through the suction line 33 in heat exchange relationship with the capillary tube 32.

The operation of the refrigerating system, specifically the compressor 30 is under the control of a control switch 34 which includes as part of its operating mechanisma feeler bulb 35 arranged to sense the evaporator tempersensed by the bulb35 whereupon the compressor is again.

deenergized and the flow of liquid refrigerant to the evaporator ceases.

.In order to maintain the freezer compartment 5 at safe sub-freezing temperatures at all times, i. e. both during the operating and idle periods of the compressor, the motor 25 which drives the fan 23 is connected in parallel with the compressor 30 and under the same control switch 34. By this arrangement the motor 25 is energized and hence the fan 23 withdraws air from the freezer compartment 5 only during the periods when the compressor is also supplying liquid refrigerant to and withdrawing'vaporized refrigerant from the evaporator whereby the evaporator is operating at sub-freezing temperatures. During idle periods of the refrigerating system when the evaporator 16 warms up, the fan motor 25 is also deenergized to prevent any substantial heat exchange between the freezer compartment 5 and the evaporator 16.

A preferred method of eifecting automatic defrosting of the evaporator 16 comprises operating the evaporator within a range of temperatures extending above and below the freezing point of water. The higher temper.- ature is chosen such that in combination with the duration of theidle period of the refrigerating unit, all of the frost which is collected on the evaporator during the operating period of the unit is melted during the :idle period. The water which forms on the evaporator by the melting of the frost flows down the sloping upper and lower surfaces of the evaporator and .into a trough 39 mounted on the back wall 15 of the cabinet liner 2 below the-rear edge 40 of the plate-type evaporator. A drain tube 41'adjacent the edge 40 provides a passageway to the trough 39 for the water draining from the upper surface of the evaporator 16.

By positioning the entire evaporator lfi within thefresh food compartment andhence within heat exchange relationship with the air contained in this compartment, there is provided an evaporator arrangement which can be raised to defrosting temperatures during each idle period of .the refrigerating .unit without materially raising the temperatures :within the freezer compartment 5.

This automatic defrosting can also be obtained regardless of the type of evaporator employed. During each operatingperiod of the refrigerating unit the introduction of liquid refrigerant into the evaporator coils 18 and the withdrawal of vaporized refrigerant by the compressor quickly lowers the temperature of the evaporator structure tobelow freezing temperatures at which temperatures the freezer air circulated over the evaporator 16 is cooled to sub-freezing temperatures before being returned to the freezer compartment. .During the subsequent idle period for the refrigerating unit, the evaporator 16 attainsa temperature above freezing so that frost formed during the coolingcycleis melted and collected in trough 39 from which it may be disposed of by flowing the defrost-water downalong one corner of the liner 2 and out through :the drain .43 positioned in the bottom of the liner .2. .A.'suitable drip pan 44 may be provided in heat exchange relationship with the compressor '30 or condenser for receiving and :evaporating the defrost water.

While there has been shown and described a'specific embodiment of the invention, .it is to be understood that the invention is not limitedto'the particnlar construction shown and described audit is intended, by the appended claims, to :cover all modifications within the spirit and scope of the present invention.

What I claimasnew and desire .to secureby Letters Patent-of the United .States is:

1. A refrigerator cabinet including an insulating partition dividing ,said'cabinet into an upper freezer compartmerit and a lowergfresh food compartment, a single'evaporatorzfor icooling both .of said compartments, said evaporator being of the plate type and being disposed in said fresh food compartment .in spaced relationship with 1 the top wall thereof, the peripheraledges of said evaporator being in sealing contact with the side, front and rearwalls of-said 'fresh'food compartment, and means for circulating air from said freezer compartment over the upper surface of said evaporator and back into said freezer compartment whereby said freeze compartment is cooled by air circulated by said circulating means over the upper surface of said evaporator and said fresh food compartment is convection cooled by the lower surface of said evaporator.

2. A refrigerator cabinet including an insulating partition dividing said cabinet into an upper freezer compartment and a lower fresh food compartment, a single evaporator for cooling both of said compartments, said evaporator being of the plate-type and being disposed in the top of said fresh food compartment in spaced relationship with said partition and inclined downwardly toward the rear of said compartment, the edges of said evaporator substantially contacting the adjacent walls of said fresh food compartment, a drip trough mounted on said rear wall below said evaporator having a forward edge extending beneath the rear edge of said evaporator, means for circulating air from said freezer compartment over the upper surface of said evaporator and back into said freezer compartment over the upper surface of said evaporator and back into said freezer compartment whereby said freezer compartment is cooled by air circulated by said circulating means over the upper surface of said evaporator and said fresh food compartment is convection cooled by the lower surface of said evaporator.

3. A refrigerator cabinet including an insulating partition dividing said cabinet into an upper freezer compartment and a lower fresh food compartment, a single evaporator for cooling both of said compartments, said evaporator being of the plate-type and being disposed in said fresh food compartment in spaced relationship with said partition and with the peripheral edges thereof in sealing contact with the side, front and rear walls of said fresh food compartment, electrically operated means for cir' culating air from said freezer compartment over the upper surface of said evaporator and back into said freezer compartment whereby said freezer compartment is cooled by air circulated by said circulating means over the upper surface of said evaporator and said fresh food compartment is convection cooled by the lower surface of said evaporator, electrically operated compressor means for periodically supplying liquid refrigerant to said evaporator, and common means for controlling the energization of both said circulating means and said compressor means.

4. A refrigerator cabinet including an insulating partition dividing said cabinet into an upper freezer compartment and a lower fresh food compartment, a single evaporator for cooling both of said compartments, said evaporator being of the plate-type and being disposed in said fresh food compartment in spaced relationship with said partition, the peripheral edges of said evaporator being in sealing engagement with the side, front and rear walls of said fresh food compartment, means for circulating air from said freezer compartment over the upper surface of said evaporator and back into said freezer compartment whereby said freezer compartment is cooled by air circulated by said circulating means over the upper surface of said evaporator and said fresh food compartment is convection cooled by the lower surface of said evaporator.

References Cited in the file of this patent UNITED STATES PATENTS 2,511,851 lwashita June 20, 1950 2,647,375 Zearfoss Aug. 4, 1953 2,692,482 Shoemaker Oct. 26, 1954