US3050956A

US3050956A - Refrigerating apparatus with frost free compartment

Info

Publication number: US3050956A
Application number: US41612A
Authority: US
Inventors: Leonard J Mann; John J O'connell
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1960-07-08
Filing date: 1960-07-08
Publication date: 1962-08-28
Anticipated expiration: 1979-08-28

Description

Aug. 28, 1962 1.. J. MANN ETAL 3,050,956

REFRIGERATING APPARATUS WITH FROST FREE COMPARTMENT Filed July 8, 1960 4 Sheets-Sheet 1 2 3 INVENTORS L eonard J. Mann The/r Attorney Aug. 28, 1962 1.. J. MANN ETAL REF RIGERATING APPARATUS WITH FROST FREE COMPARTMENT Filed July 8, 1960 4 Sheets-Sheet 2 lllllH l l lllllll I IIHIH w ll I/I'H PHI I I i l H III III: III! L'JJ.

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Their Attorney Aug. 28, 1962 L. J. MANN ETAL 3,050,956

REFRIGERATING APPARATUS WITH FROST FREE COMPARTMENT Filed July 8, 1960 4 Sheets-Sheet s INVENTORS Leonard 4. Mann BY J /m J. OGonne/l Their A/fom ey Aug. 28, 1962 1.. J. MANN ETAL REFRIGERATING APPARATUS WITH FROST FREE COMPARTMENT Filed July 8, 1960 4 Sheets-Sheet 4 Jill. M 26 L M 2 2 2 2 O M. n 3 8 5 T I 9 8 2 $3 2 2 (ll 2 9 0 2 7. 2 B 2 2 2 0 0 3 3 0 9 5 9 2 2 o L A wm mfl i l l ll mw mw am HHHHHH 1 IHIIHIIHH INVENTORS Leonard ,1. Mann Th'r Attorney Fig. 5

3,@5il,956 Patented Aug. 28, 1962 .513 filing REFRIGERATING AIPARATUS WITH FROST FREE COMPARTMENT Leonard J. Mann and John J. OConnell, Dayton, Uhio, assiguors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed July 8, 1360, Ser. No. 41,612 5 Claims. (Ul. 62-283) This invention relates to refrigerating apparatus and more particularly to household refrigerators with above and below freezing compartments in which frost will not collect.

Refrigerators that are free of frost are popular. Be-

cause of the high sale price, they are limited to those having larger incomes. This is particularly caused by the fact that these frost free refrigerators have been built with separate evaporators for each compartment. Attempts have been made to cool both compartments with a single evaporator. However, the rapid accumulation of frost from the air received from the above freezing compartment causes the evaporator air spaces to become rapidly clogged with frost so as. to prevent the proper circulation of the air between the compartments and the evaporator. This requires frequent defrosting. Furthermore, because of the relatively large accumulation of frost where the circulating air first contacts the evaporator, it is difficult to defrost the evaporator rapidly enough to prevent the below freezing compartment temperature from rising an undesirable amount.

It is an object of this invention to provide an arrangement in which a single evaporator, although it cools air from both the above and below freezing compartments, is shielded from substantially all the moisture carried by the above freezing compartment air in circulation.

It is another object of this invention to remove most of the moisture from the air from the above freezing compartment in the form of frost before it contacts the surfaces of the evaporator which cools the air of both the above and below freezing compartments.

These and other objects are attained in the two forms shown in the drawings in which the refrigerator cabinet is provided with separate above and below freezing compartments; In the one form, air from the below freezing compartment is drawn through the heat transfer duct within a duct from which air from the above freezing compartment is drawn. The heat transfer surfaces are maintained at a below freezing temperature by the cold air from the below freezing compartment. The moistore-laden air from the above freezing compartment flows through its outlet duct in heat transfer relation with the cold heat transfer surfaces and deposits the greater portion of its moisture in the form of frost upon the heat transfer surfaces. After this heat transfer, the air from both compartments is drawn through an evaporator maintained at about F. by a fan which discharges the air back into both the above and below freezing compartments. The air to the above freezing compartment is controlled by a thermostatically controlled valve controlled by the temperature of the air flowing out of the above freezing compartment. The refrigerating system supplying refrigerant to the evaporator is controlled by a thermostat bulb located adjacent the inlet to the below freezing compartment.

In the second form, separate air circuits are provided for the below and above freezing compartments. The air from the below freezing compartment is drawn through the evaporator maintained at about 0 F. by a fan which discharges the air back into the below freezing compartment. The air from the above freezing compartment is drawn through a heat transfer device which is cooled by the cold air discharged from the fan which circulates the air from and to the below freezing compartment. This air from the above freezing compartment is drawn through the second air circuit and heat transfer device and returned to the above freezing compartment. The above freezing compartment air is cooled by the heat transfer device and the moisture in this air is removed in the form of frost on the heat transfer device during the operating periods. In both the forms, the moisture-laden air is prevented from contacting the evaporator so that the evaporator does not frost rapidly and does not become so frosted as to prevent the how of air through it. Any form of defrosting means may be provided to separately defrost the evaporator and the heat transfer device.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein [preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a front vertical sectional view taken along the line 1-1 of FIGURE 2 of a two-compartment refrigerator embodying one form of our invention;

FIGURE 2 is a transverse vertical sectional view taken along the line 2-2 of FIGURE 1;

FIGURE 3 is a fragmentary vertical sectional view taken along the line 33 of FIGURE 1;

FIGURE 4 is a front vertical sectional view taken substantially along the line 4-4 of FIGURE 5 of a second form of the invention;

FIGURE 5 is a transverse vertical sectional view taken along the line 5-5 of FIGURE 4;

FIGURE 6 is a wiring diagram for the form shown in FIGURES l to 3; and

FIGURE 7 is a wiring and control diagram for the form shown in FIGURES 4 and 5.

Referring now to FIGURES 1 to 3, there is shown an insulated refrigerator cabinet 20 having side walls 22, insulated top wall 24, insulated bottom wall 26 and a horizontal intermediate wall 28 dividing the cabinet into an upper above freezing compartment 30 and a lower below freezing compartment 32. The below freezing compartment 32 is provided with an evaporator intake air duct 34 extending out from the upper sides down into the interior of a larger discharge air duct 36 located in the same side wall 22 extending downwardly from the lower side of the above freezing compartment 30. Between the evaporator intake duct 34 of the below freezing compartment and the discharge duct 36 of the above freezing compartment are provided fins or other heat transfer surfaces to provide an extensive surface by which air from the above freezing compartment can attain adequate contact and be cooled. The air passing through the evaporator intake duct 34 is at a temperature normally below 5 F. so that it is maintained at a relatively cold temperature. Since it is of metal, it provides a aoeasee cold surface on which moisture from the moisture-laden air discharged from the above freezing compartment will collect upon in the form of frost. This dries the moistore-laden air.

Above [the bottom wall 26 there is provided a primary refrigerant evaporator 33 of the vertical fin and tube type located directly beneath the false bot-tom wall to of the compartment 32. Preferably, this wall it is in direct contact with the fins of the evaporator 38 to provide direct conduction for freezing water in ice trays 41 and maintaining frozen foods at a low temperature. This evaporator 33 is located within an evaporator compartment 46 provided between he false bottom wall 40 directly above the insulated bottom wall 26. The vertical fins of the evaporator 33 extend from side to side. On the left side of the evaporator 38, there is provided a centrifugal fan 42 having an inlet 44 communicating with the evaporator compartment 45 and having a fan scroll '48 formed in the bottom wall. The fan 42 is driven by an electric motor t) extending through the bottom wall 26.

The air from the scroll 48 is discharged through an evaporator discharge air duct 52 formed in the left side wall 22. Some of this air is discharged through an opening 54 in the upper left side of the below freezing compartment 32, while the remainder is discharged through an evaporator discharge duct 56 in the left side wall of the above freezing compartment 36. The duct 56 discharges the air through an upper discharge outlet 58 in the upper side Wall of the above freezing compartment 30. The discharge through this outlet 58 is controlled by a damper 60 which in turn is controlled by a thermostatic device including an actuating bellows 62 connected by a capillary tube 64 with a thermostat bulb 66 located adjacent the air outlet 68 of the above freezing compartment 30.

A conventional refrigerating system is provided including a sealed motor-con1pressor unit '70, a condenser 72 and a capillary tube rest-rictor 74 located in the machinery compartment 76 operatively connected to the evaporator 38. The duct 34 is provided with an electric defrost heater 78 for melting frost from the outer surfaces of the duct 34 and the fins 35 in between the duct 34 and the duct 36. The evaporator 38 is provided with a separate defrost heater St} located in the bottom of its fins. The frost water during the energization of the defrost heaters 78 and 8b is collected by a discharge device or drain 82 directly beneath the duct 34 which carries away the defrost water from both the duct 34 and the evaporator 38. It is located in a shallow well beneath the duct 34.

The evaporator 38 is provided with a defrost limiter thermostat 84 to terminate the defrosting periods. The refrigerating system is normally cont-rolled by a thermostat bulb 86 located adjacent the discharge opening 54- in the left side wall of the below freezing compartment 32. The outlet opening is designated by the reference character 88 and connects directly with the duct 34 As shown in FIGURE 6, the motor for the sealed unit 70 as well as the fan motor 50 has one terminal connected to the supply conductor 9d. The second terminal of each of these

motors

70 and 50 is connected in series with the thermostatic switch contacts 92 controlled according to the temperature of the thermostat bulb 86 which is responsive to the air delivered to the below freezing compartment 32. This thermostatic switch 92 is connected in series with a defrost timer 94 which in turn is connected to the second supply conductor 96. An additional conductor 93 connects the conductor 90 with the defrost timer 94 to supply current for the timin g mechanism, such as a clock mechanism.

The defnost timer 94 is arranged to periodically disconnect the thermostatic switch 52 from the supply conductor 96 to prevent the operation of the compressor motor 70 and the fan motor 5%. During this time, the

timer closes switch contacts which energize the defrost circuit which includes a conductor E21 connecting in parallel with the defrost heaters 73 and 8t) and a conductor 123 connecting with defrost limiter thermostat and a conductor 125 connecting the limiter thermostat with the timer. When the limiter thermostat 84 reaches a high enough temperature to insure defrosting of the evaporator 33, it operates through an operating connection 127 to return the defrost timer 94 to the normal refrigerating condition in which the thermostat 92 is connected through the timer 9% to the conductor as.

Through this arrangement, periodically, refrigeration is stopped and the defrost heaters 78 and 89 energized for a sufficient period of time to melt the frost from the evaporator intake duct 34 and the fins 35 as well as the evaporator 33. This defrost water is collected in the well beneath the duct 34 and discharged through the defrost water discharge device 82 into the machinery compartment 76. In this form, the humid air from the above freezing compartment is dehumidified by the heat transfer with the evaporator intake duct 34 prior to its joining with the cold air issuing from the duct 34. Thus, all the air is at a low relative humidity prior to its contact with the evaporator 38. This reduces the amount of frost depositing on the evaporator 38 in the flow of air to the inlet 44 of the fan 42 so that the evaporator will not become so clogged with frost that free air flow is retarded. The reduction in the accumulation of frost also makes possible rapid and complete defrosting of the evaporator 33 during the defrosting periods.

In FIGURES 4 and 5, there is shown a form in which the cabinet is similar but slightly different and is designated generally by the reference character 22%. It includes side walls 222, an insulated top wall 224, an insulated bottom wall 226 and a horizontal intermediate wall 228 which separates the upper above freezing compartment 23% from the lower below freezing compartment 232. The lower below freezing compartment 232 has a false bottom wall 246 providing an evaporator compartment are between it and the insulated bottom wall 226. A vertically finned evaporator 238 is provided in the evaporator compartment 246 with the tops of the fins in contact'with the false bottom wall 24% to promote freezing of the ice in the ice trays usually provided in this compartment. The below freezing compartment 232 is provided with an outlet 238 connecting with an evaporator inlet duct 234 in turn connecting with one side of the evaporator compartment 246.

The opposite side of the evaporator compartment is provided with the fan 242 having an inlet 244 communieating directly with the evaporator compartment 246 on the outlet side of the evaporator 23%. The fan 242 is driven by an electric motor 259 and has a discharge scroll 248 discharging into an upwardly extending evaporator outlet or discharge duct 252 along the left side wall of the evaporator compartment 246. This evaporator outlet duct 252 terminates in a discharge outlet 254 at the upper portion of the left side of the below freezing compartment 232. The evaporator 238 is maintained at about -12 F. by a conventional refrigerating system including a sealed motor-compressor unit 270, a condenser 272 and a capillary tube restrictor 274 located in the machinery compartment 276 beneath the bottom insulated wall 226. The circulation of the air from the below freezing compartment in heat transfer with the evaporator 238 by the fan 242 keeps the compartment 232 at temperatures between 0 and 5 F. insuring good storage conditions for frozen foods and rapid freezing of water in any ice trays.

For the purpose of cooling the above freezing compartment 234 the outer side of the evaporator outlet duct 252 is provided with a heat transfer wall 253 provided with outwardly extending fins 235. Air flows in a second air circuit out of the above freezing compartment 230 through two outlets 266 on the lower left side wall thereof which connect with downwardly extending ducts 236 forming part of the duct 256 and containing the two portions of the fins 235 located on opposite sides of the dual spaced dividing walls 251 between which is provided an upwardly extending duct. This air passes downwardly in the ducts 236 through the fins 235 on the outermost side of the dividing wall 251 to the bottom 249 of the duct 256 in the left side wall. This duct 256 encloses the vertical fins 235 and conveys the moisture-laden air from the above freezing compartment 230 through the outer ducts 236, through the fins 235 where the air is cooled and the moisture deposited in the form of frost. The air then flows beneath the lower edges of the fins 235 and the dividing walls 251 into the upwardly extending duct portion 257 located between the dividing walls 251 and containing a central set of vertical fins 235. This duct portion 257 extends upwardly to the inlet of the centrifugal fan 320 driven by the electric motor 322. The fan 320 has its inlet on the motor side and discharges the air upwardly through the discharge outlet 324 forming a duct which connects with the outlet 326 discharging into the upper left side of the above freezing compartment 230.

A thermostat ibulb 328 adjacent the outlet 326 controls the operation of the fan motor 322 while a thermostat bulb 286 located adjacent the outlet 254 of the below freezing compartment 232 controls the operation of the sealed motor-compressor unit 220 and the fan 250 as shown in the wiring diagram in FIGURE 7. The evapo- T8201 238 is provided with a defrost heater 280 while the heat transfer surface 253 is provided with a separate defrost heater 278. The control system shown in FIG- URE 7 includes a supply conductor 290 connecting with the compressor motor 270 and the

fan motors

250 and 322. The second terminals of the compressor motor 270 and the fan motor 250 are connected to a snap acting switch 292 controlled according to the temperature of its thermostat bulb 286. The second terminal of the fan motor 322 is connected through the snap acting switch 331 and the conductor 333 to a junction connecting with the second terminal of the switch 292. This junction is connected to one terminal of the defrost timer 294 having its second terminal connected to the second supply conductor 296. The defrost timer is supplied independently through a conductor 298 from the supply conductor 290 to operate the clock or other timing device.

According to this arrangement, the compressor motor 270 and the fan motor 250 will cycle according to the temperature of the thermostat bulb 286 to maintain the below freezing compartment 232 at a desired temperature. The switch 292 may be set, for example, to close at +2 F. and to open at 10 F. The switch 331 may be set to close at 36 F. and to open at 32 F. Periodically, the timer 294 will disconnect from the junction to deenergize [the compressor motor 270 and the

fan motors

250 and 322 and energize the

defrost heaters

278 and 280 through the limiter thermostat 284. This energization will continue until the limiter thermostat 2S4 reaches its tripping point at a temperature sufiiciently high, such as 50 F, to insure defrosting of both the evaporator 238 and the heat transfer surfaces 253 and the fins 235. When this temperature is reached, the defrost limiter 284 will return the defrost timer 294 to the normal condition, thus reenergizing the compressor motor 270 and the

fan motors

250 and 322 and at the same time deenergizing the

defrost heaters

278 and 280.

This arrangement completely isolates the air of the above freezing compartment from the evaporator 238 and the air circuit of the below freezing compartment 232. By providing separate air circuits, the major por-- 6 herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A refrigerator including insulating means enclosing a below freezing compartment and an above freezing compartment, means forming an evaporator compartment outside said compartments, an evaporator portion within said evaporator compartment, first air duct means having a first portion extending from said below freezing compartment to said evaporator compartment and having a second portion extendingfrom said evaporator compartment to said below freezing compartment, said air duct means in said first portion including an air to air heat transfer device having heat transfer wall means normally maintained at below freezing temperatures by air flow through said first duct means, second air duct means having a first portion extending from and carrying air from said above freezing compartment first into heat transfer relation with said heat transfer wall means of said heat transfer device and thereafter to said evaporator compartment and having a second portion extending from said evaporator compartment to said above freezing compartment, said heat transfer wall means being located to keep separated the air from said below and above freezing compartments in said heat transfer device, and means for circulating air simultaneously through said first and second duct means into heat transfer relation with said heat transfer device and thereafter through said evaporator compartment into heat transfer with said evaporator portion.

2. A refrigerator including insulating means enclosing at below freezing compartment and an above freezing compartment, means forming an evaporator compartment outside said compartments, an evaporator portion within said evaporator compartment, means for circulating air from said below and above freezing compartments simultaneously through said evaporator compartment in heat transfer with said evaporatorportion and in contact with each other and returning the cooled air to said below and above freezing compartments, means for controlling the circulating air to maintain the above freezing compartment at temperatures above freezing, and air to air heat transfer means having heat transfer Wall means located between and separating the colder air leaving the- 3. A refrigerator including insulated means enclosing a below freezing compartment and an above freezing compartment, means forming an evaporator compartment outside said compartments, refrigerant evaporating means associated with said evaporator compartment, means for circulating air from said below and above freezing com-v partments through said evaporator compartment in heat transfer with said evaporating means and returning the cooled air to said below and above freezing compartments, and means for removing moisture from the air circulating from said above freezing compartment while it is separated from the below freezing compartment air prior to contacting said evaporating means.

4. A refrigerator including insulated means enclosing a below freezing compartment and an above freezing compartment insulated from each other, means forming an evaporator compartment outside said compartments, refrigerant evaporating means associated with said evaporator compartment, means for circulating air from said below and above freezing compartments through said evaporator compartment in intermixture with each other and in heat transfer with said evaporating means and returning the cooled air to said below and. above freezing compartments, and means for removing moisture from the air circulating from said above freezing compartment prior to contacting air circulating from said below freezing compartment and prior to its entrance into the evaporator compartment.

5; A refrigerator including insulated means enclosing a below freezing compartment and an above freezing compartment, means forming an evaporator compartment outside said compartments, refrigerant evaporating means associated with said evaporator compartment, means for circulating air from said below and above freezing compartments through said evaporator compartment in heat transfer with said evaporating means and returning the cooled air to said below and above freezing compartment, and means for substantially cooling the air circulating from said above freezing compartment while it is sepa- :2: rated from the below freezing compartment air prior to its circulation in heat transfer with said evaporating means.

References Cited in the file of this patent UNITED STATES PATENTS 2,265,634 Cumming Dec. 9, 1941 2,416,354 Shoemaker Feb. 25, 1947 2,481,616 Richard Sept. 13, 1949 2,546,363 Iaeger Mar. 27, 1951 2,863,300 Murphy Dec. 9, 1958 2,889,692 McGraw June 9, 1959 2,982,115 Wurtz May 2, 1961