US2700532A - Temperature control apparatus for refrigerators - Google Patents

Description

Jan- 25, 1955 H. w. scHAEFER 2,700,532

TEMPERATURE CONTROEAPPARATUS FOR REFRIGERATORS Filed March 22, 1952 2 Sheets-Sheet l F/qn l..

. JNT/ENTOR. #Maw af. .wf/@5F09 A@ en r.:

Jan- 25, 1955 H. w. scHAl-:FER

TEMPERATURE CONTROL APPARATUS FOR REFRIGERATORS 2 Sheets-Sheet 2 Filed March 22, 1952 JNVENTOR H/IIEOLD w. .5U/MFM United States Patent() M TEMPERATURE CONTROL APPARATUS FOR REFRIGERATORS Harold W. Schaefer, Rosemont, Pa., assigner to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvania Application March 22, 19572, Serial No. 277,947

3 Claims. (Cl. 257-9) The invention hereinafter disclosed and claimed is concerned with refrigeration control, relating especially to refrigerators of the type in which a single evaporator, or other cooling means, provides refrigeration within each of a pair of adjacent compartments.

In considering the invention it is to be borne in mind that it has proven desirable to provide within a refrigerated cabinet not only a freezer compartment, but also a compartment maintained at a temperature above the freezing point of water, and in which may be preserved fresh fruits, vegetables, or other foodstuffs which should not be subjected to sub-freezing temperatures. A relatively simple and inexpensive way of constructing such a refrigerator comprises dividing the space defined by the inner liner of the cabinet into upper and lower compartments by means of a generally horizontal partition or baille which limits, but does not eliminate, circulation of air between said upper and lower compartments. The partition is so shaped and disposed within the cabinet as normally to provide for limited circulation of cooling air between the two compartments, and this may be accomplished most readily by spacing the front and rear edges of the partition from the adjacent walls of the cabinet. Commonly the refrigeration system is responsive to the temperature of the evaporator `which cools (and the walls of which may define) the freezerk compartment, and this invention has to do with refrigerators of the forcgoing type in which at least the major portion of thecooling within the higher temperature compartment is accomplished by circulating air from the latter compartment around said baille or partition and in heat exchange relation with the evaporator of the freezer compartment.

While constructions of the type described are well known and are advantageous, they have been found, in practice, to be subject to a difficulty, particularly in that a reduction in the ambientV temperaturek may result in r over-cooling of the fresh food' compartment and even in freezing of foods therein. This has proven yto be the case even though an adjustable', flow-restricting damper be provided to limit the pasage of air about the partition.

Accordingly, and with the foregoing in mind, it is the primary object of the present invention to overcome the above-mentioned difllculty by making it possible to restrict or to eliminate the circulation of air about the baille whichseparates the two compartments and, particularly, to provide for conjoint restriction of circulation and addition of heat to thevcabinet. More specifically the invention has as an object effecting advantageous control of the heating means through the agency of means which restricts circulation. v j

ln an important aspect of the invention it is contemf plated that the heat shall be applied in such a way as to operate to limit circulationof air between the two compartments of a refrigerator, and that application of the heat shall be under the control of a damper which further serves to restrict circulation of air around the baille.

Broadly, application of heat yin such manner as to serve as means limiting circulation of air about the baille of a refrigerator is fully described and claimed in the co- Y pending application of Lloyd A. Staebler, bearing Serial No. 277,774, tiled March 2l, 19,52, and assigned to'the assignee of the present invention. As indicated above it is withimproved apparatus for controlling the application of heat that the instant invention is particularly concerned,v

In accordancewith the said co-pending disclosure,l

2,760,532 s Patented Jan. 25, 1955 ICC means is provided which is effective to apply heat in the region of that edge or portion of the baille about which downow of cooled air normally takes place. It has been found that application of a relatively small quantity of heat in this region creates an upward current of warmed air which is in opposition to the normal downward ilow of air effective to cool the lower compartment. When heat is applied in this way the quantity of heat required to prevent undue reduction of the temperature within thelower compartment is considerably less than the quantity which would be required if the heat were to be applied at a location remote from the baille. There is created whatmight be referred to as a heat block impeding or substantially preventing the normal circulatory ilow ofy air around the baille and, consequently, serving to reduce the effectiveness of the upper evaporator in cooling the lower compartment. The Staebler invention is particularly concerned with utilization of this heat block as the sole means for rcontrolling the ilow of air around the baille.

Further, and as indicated above, efforts have been made to limit the cooling within the lower compartment by the use of a pivoted damper which may be moved, with relation to the baille, to a position such that it impedes the normal exchange of air around the baille, and thereby correspondingly reduces the circulatory llow of air which is the primary source of cooling for the lower compartment. As indicated above, this expedient has not alone proven to be satisfactory and, withrespect to the Staebler invention, it is to be noted that the Staebler apparatus necessitates the use of a switch or some suitable control circuit for energizing the heater when the ambient temperature is relatively low. ln particular accordance with my invention, a heater is utilized-preferably being mounted near the baflle in general accordance with the teaching of the aforesaid Staebler disclosure-and the baille damper is made to serve two purposes in that it not only contributes to the desired limitation of air llow, but also because it operates as a means for controlling energization of the heater. As will become more clear as the description proceeds, the present inventioninvolves recognition of the fact that the heater should preferably be energized conjointly with closing of the damper. l The manner in which the foregoing objects and advantages may best be achieved will be understood from a consideration of the following detailed description, taken together with the accompanying drawings, in which:

Figure l is a Vertical, sectional illustration of a refrigerator of the type to which the invention is particularly applicable;

Figure 2 is a somewhat diagrammatic view of the upper portion of the inner liner of a refrigerator, showing an advantageous way in which the heater may be applied to the outer surfaces of the liner, and illustrating the heater supply circuit and control switch;

Figure 3 is a fragmentary, front elevational view, on an enlarged scale, illustrating the upper portion of a refrigerator of the type shown in Figure l;

Figures 4 and 5 are fragmentary, sectional views illustrative of the manner in which air circulates under different conditions of operation; and,

Figure 6 is a sectional View showing latch means which may be employed to hold the damper in'open position.

Now making more detailed reference to the drawings, and particularly to Figures l, 2 and 3 thereof, it will be seen that the invention is therein illustrated as embodied in a domestic refrigerator comprising an outer shell 10 and an inner shell or liner member 11, spaced inwardly of and insulated from the outer shell 10 by `means of any suitable insulation, shown at 12. 13 and 14 are adapted -to seat against the forward face of the cabinet and provide independent access to different sections of the cabinet. It will be understood that the refrigerator also includes a compressor-condenser unit of any desired type, but illustration of this portion of the apparatus is not necessary herein since the present invention is not concerned therewith.

vAs clearly appears in the drawing, the space within the inner liner v11 is sub-divided into an upper rela.

tively low temperature storage compartment defined by A pair of doors 16, by means of a tray-like partition or baie designated by .the reference character l17. As is clearf-rom acomparison of Figures l and 3, vboth the evaporator 15 and the baiiie 17 substantially span the width of the space defined bythe inner f'liner, the baffle 17 :being s o shaped and 'fdisPQScd' .Within the .cabinet as :to l:provide en Vupflow zone or space 1 8 at the forward edge thereof and a downflow zone -19 along the rear edge thereof.

The center `cross-rail 2,0 against which -the adjacent edges of the doors seal, provides support, through the agency of a hinge member "2,1, for an adjustable damper 22 .having therein a depression or pocket 23 (see -particularly Figures 4 and 5). This damper also spans lthe width of the cabinet and, as aforesaid, serves not only as an aid inrlimitingcirculation of air around the batiie 17,

lhut `also .as a means .for controlling the application of eat.

Turning now vto the heating means, and making referen ce `to Figures 2., .4 and 5, the heater 24, which preferablycfmprises several loops of lrelatively -high resistance wire secured in convoluted arrangement across the outside of the Lback surface of inner liner 11, is disposed at the general level of the rear edge of the partition 17, that'is, in the region of the downflow gap or laperture 19. .It will be observed that the heater substantially sQtXlS Vthe width ofthe cabinet, thereby insuring that the applied heat will be effective along the entire back edge of bafe 1'7.

The heater, which is illustrated diagrammatically in Figures 4 and 5, is .secured to the back surface-of the inner liner in any convenient manner, a strip of adherent tape, 2S (Figure'Z.) being used for this purpose. Apair of terminals .shown at 26 are ladapted for connection to any suitable source of power, .and the heater is placed across the line through conductors 28 and 29 and through the agency of a plunger type switch 27, which is mounted in the cross-rail 2t).

As appears in Figures 4 and 5 the plunger 30 which actuates .the switch extends outwardly of the cross-rail 2 0 and toward .he aforesaid pocket 23 formed in the confrontingportion of damper 22. The damper is movable between an vopen position shown in Figure 4, in which position the .plunger 30 is depressed by contact with .the pocket v23 and the heater is de-energized, and a closed position in which the damper bridges the gap between fthe cross-rail structure and the baftie and bears against the forward edge of the latter. In this closed position lof the damper the plunger 3) is of course extended and the contacts of the switch are closed, thereby effecting energizaticn of the .heater 24. Referring to Figure 6 it will be seen that the damper may conveniently be provided with an aperture 3l cooper-able with a manual-ly operable latch member 32 effective to hold the damper in its open position. As will be pointed out hereinafter- ,the latch is released and the damper is lowered during seasons, and under conditions, when overcooling of the lower compartment 16 -might be expected.

When ,the damper 22 occupies the open position shown in Figure 4, that is, when there is no substantial possibility of over-cooling the lower compartment 16, the operation of the refrigerator is characteristic of 'known apparatus of the kind in which circulation of air around the baffle is utilized to provide cooling of the compartment below said baie. The normal circulatory iiow of air is represented by the arrows applied to Figure 4 and this .normal phase of operation will be understood without further description.

When it is desired to limit cooling of the lower comparrnent. a condition which most commonly obtains during the colder months of the year when the ambient temperature may drop rather sharply, the latch 32 is released and. the damper is moved to the closed position shown in Figure 5. Movement of the damper to this latter position serves not only yto limit the circulation of air lupwardly across the forward edge -of the bathe 17, but also7 as aforesaid, energizes the' heater element 24. The heat generated by the element 24 not only adds directly to the heat load .normal-ly resulting from leakage through the cabinet insulation, but also warms the adiacent portion of inner liner 1,1 and .results in turbulence at the vicinity of the rear ,edge of the baffle 17 and, ultimately, in creation of a zone .or column of warm air tending to flow upwardly ,around .the rear edge of the bafe, as is indicated by the .arrows applied to Figure This vturbulence and upward flore.7 cfu/armed which constitutes the heat block referred to hereinabove, to-

gether with the direct addition to the cabinet heat load, serves .very Yeffectively to prevent lexcessive cooling of the lower compartment 16,. It has been found that an input of approximately twelve Watts is sutiicient to accomplish the purposes of the invention, and it will be appreciated that application of wattage as low as this is not sufficient to interfere appreciably with the proper operation lof vthe evaporator 15 or with its ability to maintain frozen foods at the proper, predetermined temperature.

Under this 'latter condition of operation, and due to the l.conjoint action ofthe damper and the application of heat, the normal circulatory flow of air between the two compartments is virtually terminated, although a relatively slow circulatory flow of air continues to take place within said lower compartment, as is represented by arrows shown below lthe baffle in VFigure 5.

Due to the fact that in a refrigerator of the type to which the invention is applicable there is normally provided freedom for air -flow across both the forward and the rear edges of `the baie, or through suitably spaced apertures .provided Ain the baie, it will be appreciated that closing of the damper alone isnot sufficient to eliminate interchange of air between the two compartments, since air cooled within the upper compartment is still free to flow .downwardly into the lower compartment through the .gap or aperture not yprovided with a damper, displacing an equal amount of air which tiows upwardly through the same gap .or aperture. When, on the other hand, a small amount of heat is applied coniointly with closing of the .damper 22 it is readily possible to prevent'excessive cooling within the lower compartment.

During 'the day, the temperature of the kitchen or other room in which the refrigerator is located tends to rise considerably, as compared with the vover-night temperature, and it might at tirst appear that application of heat together with closing of the damper would result in in sucient cooling of the lower compartment or in objectionable interference with the recovery characteristics of 'the refrigerator. This however has not proven to be the case, as will be appreciated when it is recognized that during colder seasons .of the year, when closing of thedamper and use of the heater is most advantageous, the relative humidity of the amibent atmosphere is low. Under conditions .of low relative humidity the evaporator Aand other cooled surfaces of the refrigerator are fully effective in transferring sensible heat, rather than having `a `considerable portion of -the capacity utilized in eifectingtransfer of latent heatwith resultant condensation .of moisture-,as occurs during warmer seasons when the relative humidity is higher.

In practice it has been found that maintenance of satisfactory temperatures within the lower compartment during the winter season requires no more attention from the user of the refrigerator .than is necessitated by closing of the damper with resultant automatic energization of the heating. means.

From the yforegoing description it will be understood that my invention provides an improved refrigerator in which undue reduction in the temperature of the fresh food compartment is prevented by the simple expedient of causing the damper to serve the dual purposes described above, .and this result is accomplished without in any way interfering with the maintenance of the low tem- Piaturcs lesir'ed within the freezer compartment.

They invention, in its broader aspect, contemplates location of the 'heater Ain positions other than the position shown and .described herein; for example, the heater might be so situated, at a level further down the -inner lliner within the food storage compartment, that the a-ir heated thereby rises towardy the normal downflow aperture of the baffle assembly and therefore creates a rising current of air which is in .counter-How relation with respect to the circulation which obtains under normal operating conditions. YIt will ,be recognized however that the foregoing, and such other changes as may come within .the scope of the appended claims, are within the purview of the invention.

I claim:

l. 111 refrigeration apparatus, a cabinet, a baffle or partition disposedy within said cabinet and separating the space therein into upper and lower compartments, the upper ofsaid compartments .having cooling means in heat exchange relation'therewith, and said baflie having a first edge portion spaced from a wall portion of the cabinet and another edge portion spaced from another wall portion of the cabinet, whereby to provide for limited circulation of cooling air between said two compartments, and means preventing over-cooling of said lower compartment, comprising: heating means associated with the said other wall portion of said cabinet in substantial adjacency to the said other edge portion of said baille; movable damper means cooperable with said first edge portion of said baille to restrict the stated circulation of air; and control means including said movable damper means and effective to initiate operation of said heating means.

2. Refrigeration apparatus in accordance with claim 1, and further characterized in that said heating means comprises an electrical resistance heater extending along the said other wall portion of the cabinet, and being of a length substantially equal to the length of the said other edge portion of the baile.

3. In refrigeration apparatus, a metallic inner liner member dening a storage compartment, a bale mounted generally horiozntally within said inner liner member and having portions disposed in spaced adjacency with respect to interior surface portions of one wall of the inne. liner member to provide a gap through which air ma: ow, the construction and arrangement being such that ai: normally circulates downwardly through the gap an( thence returns upwardly past other portions of said baf e, and means for impeding such normal circulation o: air, comprising: an adjustable damper providing foi variation in the flow of air through said gap; an electrica resistance heater mounted upon an exterior surface portion of the saidadjacent wall of the inner liner member; and switching means for controlling said heater said switching means being operable in response to adjustment of said damper.

References Cited in the file of this patent UNITED STATES PATENTS 2,126,285 Schaaf Aug. 9, 1938 2,272,302 Krackowizer Feb. 10, 1942 20 2,600,297 Janos June 10, 1952

Images