US3004400A

US3004400A - Two compartment frost-free refrigerator

Info

Publication number: US3004400A
Application number: US41638A
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: 1961-10-17
Anticipated expiration: 1978-10-17

Description

Oct. 17, 1961 lmJ.MANN ETAL TWO COMPARTMENT FROST-FREE REFRIGERATOR Filed July 8, 1960 2 Sheets-Sheet 1 64 X 38 f 60 so 66 n}; 40 92 I zg j la5, 22 ea so -ss so 58 Fig. HVVENTURS Leonard J. Mann By John J O'Connell Their Attorney Oct. 17, 1961 L. J. MANN E TAL TWO COMPARTMENT FROST-FREE REFRIGERATOR Filed July 8, 1960 2 Sheets-Sheet 2 Fig. 3

INVENTORS Leonard J. Mann Y John JOConna/l T/reir Af/orney 3,004,400 Patented Oct. 17, 1961 3,004,400 TWO COMPARTMENT FROST-FREE REFRIGERATOR Leonard J. Mann and John J. OConnell, Dayton, Ohio, asslgnors to General Motors Corporation, Detroit,

Mrch., a corporation of Delaware Filed July 8, 1960, Ser. No. 41,638 4 Claims. (Cl. 62-156) Refrigerators are popular which are free of frost in thefood storage compartments. Because of the high selling price, they are limited to those having larger incomes. In such refrigerators, frost accumulates rapidly upon the colder evaporator. 'It is customary to provide an expensive clock defrosting device for periodically stopping the refrigerating system and using an electric heater to heat this evaporator during such a period to defrost it. This is inelficient since the electric heat uses energy in removing frost created by the previous expenditure of energy in making refrigeration.

It is an object of this invention to provide a simple economical refrigeration'and defrosting system for a frost free refrigerator.

It is another object of this invention to provide a simple refrigeration system in which the frost on the colder evaporator is removed every off cycle by the relatively warmer air circulated from the above freezing compartment.

It is another object of this invention to provide a refngerating system in which the air from the below freezmg compartment is circulated in heat transfer relation with the colder evaporator which thereby accumulates frost while the air from the above freezing compartment is circulated in heat' transfer relation with the warmer evaporator during the refrigeration cycle but during the off cycle the warmer air from the above freezing compartmentis circulated in heat transfer relation with the colder evaporator to defrost it.

These'and other objects are attained in the form shown in the drawings in which one of the vertical walls of the insulated refrigerator cabinet is provided with an evapo rator compartment having supply and return passages extending thereto from the upper, below freezing compartment. Shorter passages connect directly with the above freezing compartment. The above freezing compartment is also provided with an evaporator operating at all times above freezing temperatures which. reduces the required size of the first mentioned colder evaporator operating below freezing temperatures and accumulating frost during the refrigerating cycle. During the refrigerating cycle, a damper means closes the communication between the evaporator compartment and the abovefreezing compartment, and a continuously operating blower circulates air between the below freezing evaporator and the evaporator compartment containing the colder evaporator to keep the below freezing compartment cold while frost accumulates upon this colder evaporator.

A simple thermostatic switch operating upon a defrosting cycle in response to the temperature of the colder evaporator stops the operation of the refrigerating system at a predetermined low temperature thereof and starts it only after it has attained a temperature above freezing soas to insure its defrosting. This switch also controls the electrically operated damper so that, during the refrigerating cycle, the passages to the above freezing compartment are closed and circulation between the colder evaporator in the evaporator compartment and the below freezing compartment is assured. During the off cycle under the control of this thermostatic switch, the electrically operated damper is moved to open the passages to the above freezing compartment and to close the passages leading to the below freezing compartment so that the warmer air from the above freezing compartment circulates by the continuously operating fan over the colder evaporator to heat the evaporator to a point at which the frost thereon is melted and removed by the circulating air. The fan motor for the warmer evaporator is stopped by being connected in parallel with the compressor motor of the refrigerating system during the off cycle.

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

In the drawings:

FIGURE 1 is a vertical transverse front sectional view of a frost free refrigerator embodying one form of our invention;

FIGURE 2 is a side sectional view taken along the line 22 of FIGURE 1;

FIGURE 3 is a wiring diagram for the system shown in FIGURES l and 2; and

FIGURE 4 is a diagram of one form of refrigerating system for the system shown in FIGURES 1 and 2.

Referring now to the drawings, there is shown an insulated refrigerator cabinet 2-0 provided with vertical insulated side walls 22, an insulated top wall 24, an insu lated bottom wall 26, an insulated rear wall 28 and a horizontal insulated dividing wall 30 dividing the interior of the cabinet into an upper, below freezing compartment 32 and a lower, above freezing compartment 34. .A door .36 completes the enclosure of the compartments.

In the right side wall 22, there is provided a centrally located evaporator compartment 38 containing the colder evaporator 40. A cold air evaporator discharge duct 42 extends upwardly from the evaporator compartment 38 and discharges through an outlet 44 into the upper portion of the below freezing compartment 32 which is maintained at about 0 F. The air leaves the below freezing compartment 32 through two outlets 46 located on opposite sides of the evaporator air discharge duct 42 which connect with evaporator inlet ducts 48 extending downwardly on opposite sides of the evaporator compartment 38 to a semicircularair chamber 50 which connects with the inlet 52 of the fan 54 driven by an electric motor 56. The fan 54 is located in a separate scroll 58 which discharges into the bottom of the centrally located evaporator compartment 38.

The inner liner 60 of the above freezing compartment 34 is provided with two openings 62 in the right side wall 22 connecting directly with the dual evaporator inlet ducts 48. This right side wall 22 is also provided with an opening 64 connecting with the top portion of the evaporator chamber 3-8 immediately above the evaporator 40 as shown in FIGURE 2. Thus, each compartment has two openings connecting with the downwardly extending evaporator inlet ducts 48. Also, each compartment has an opening connecting with the upper portion of the evaporator chamber 38.

To carry out our invention, we provide an electrically operated damper means, designated by the reference character 66, shown in the full line position in FIGURE 1 closing the

openings

62 and 64 in the inner liner 60 of the above freezing compartment 34. The dotted line position 68 is also shown in FIGURE 1 in which the damper 66 closes the evaporator discharge and

inlet ducts

42 and 48 to shut off communication between the below freezing compartment 32 and the evaporator compartment 38. The damper 66 is shown as operated by a pinion 70 and a rack 72 operated by the solenoid 74 in a circuit 76 connected in parallel with the compressor motor 78 and the motor 80 which drives a fan 82 for circulating air through a warmer evaporator 84 located.

of the colder evaporator 40. These three circuits are connected in parallel with a thermostatic snap-acting switch 86 having a bulb 88 mounted upon a lower portion of the evaporator 40 and adjusted to operate upon a defrosting cycle. Preferably, this switch '86 opens when the evaporator 46 reaches a defrosting temperature, such as 36 F., and closes when the evaporator 40 reaches a temperature of -l2 F. This will maintain an average temperature of about F. in the below freezing compartment 32.

When the switch 36 is closed, the fan 82 operates to cool the above freezing compartment 34 by drawing air in through the fan inlet 90 in the baffle 92 and discharging the air through a scroll 94 connecting with the bottom of the evaporator 84 for discharging air upwardly behind the baffle 92 into the upper part of the above freezing compartment 34. The closing of the switch 86 also causes operation of the compressor motor 78 and energizes the electromagnet 74 so as to move the damper 66 from its dotted line position 68 to its full line position as shown in FIGURES 1 and 3; Connected in series with the solenoid 74 is a bimetal switch 93', preferably located in the evaporator compartment 38 and set to a close at 15 B, so as to insure that no warm air will be delivered to the below freezing compartment 32. The fan motor 56 is connected directly across the supply conductors L and L and operates continuously to circulate air through the evaporator 40 at all times.

The evaporator 84 preferably operates at a temperature of about 33 F. maintained by means of a restrictor line 127 between the evaporator 84 and the evaporator 40 so that it never accumulates any frost. Therefore,

this evaporator does not need to be defrosted at any time;

The provision of the two evaporators makes it possible for each of the evaporators to be relatively small and also makes it possible to rapidly defrost the colder evaporator 40. This is accomplished when the colder evaporator 40 reaches the cut-off point of l2 F. and opens the switch 86. This not only stops the compressor motor 78 and the fan 82 but it also deenergizes the solenoid 74 which thereby moves the damper 66 from the full line position to the dotted line position, indicated by the reference character 687 As long as the switch 86 remains in the open position, air will be drawn from the above freezing compartment 34 which is at about 36 F. in through the openings 62 in the inner liner 6% and down through the evaporator inlet ducts 48 into the inlet 52 of the fan 54 which discharges the air through the evaporator 40 to warm the evaporator rapidly and remove the frost therefrom, after which the air is discharged back into the above freezing compartment 34 through the evaporator compartment 38 and the discharge opening 64. This maintains the above freezing compartment 34 at a relatively cool temperature. This circulation continues until the evaporator 40 rises above the freezing temperature to completely melt any frost thereon. Because of the high volume of air circulated over the surfaces of the evaporator 40 from the above freezing compartment 34 at the temperature of about 36 F., the defrosting is rapid and the evaporator 49 rapidly reaches the cut-on temperature of 36. This is sufiiciently rapid that the compartment 32 which is disconnected from the evaporator compartment 38 and the

openings

44 and 46 during the off cycle does not substantially rise in temperature.

The reclosing of the switch 36 first resumes operation of the compressor motor 78 and the refrigerating system and, subsequently, upon the closing of the thermostat 5 3, causes the movement of the damper 66 from the dotted line position 68 to the full line position. This restores the normal refrigeration cycle to lower the temperature in the below freezing compartment as well as in the above freezing compartment 34. The

evaporators

40 and 84 are connected in series in an arrangement capable of maintaining the desired temperature differences; As

shown in FIGURE 4, the motor 78 drives a compressor 121 discharging into a condenser 123 which connects through a long restrictor 125 with the warmer evaporator 84 while a shorter restrictor12-7 connects with the colder evaporator 40. The outlet of the evaporator 40 connects through the suction conduit 129 with the compressor 121.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows: 7

1. Refrigerating apparatus including insulated walls enclosing an above freezing compartment and a below freezing compartment, said insulated walls being provided with at below freezing evaporatorcompartment, a cold evaporator located in said evaporator compartment, means forming in said insulated walls an air circuit connecting said below freezing compartment and said evaporator compartment, an above freezing evaporator located in heat transfer relation withsaid above freezing compartment, means providing communication between said evaporator compartment and said above freezing compartment, damper means for shutting oif communication from said evaporator compartment alternately with said above freezing and below freezing compartments, fan means for forcibly circulating air alternately from said below and above freezing compartments through said evaporator compartment in heat transfer relation with said below freezing evaporator and return to said below and above freezing compartments alternately, and means for stopping refrigeration in said below freezing evaporator during the time communication is shut ofi between said below freezing and evaporator compartments.

2. Refrigerating apparatus including insulated walls enclosing an above freezing compartment and a below freezing compartment, said insulated walls being provided with a below freezing evaporator compartment, a cold evaporator located in said evaporator compartment, means forming in said insulated walls an air circuit connecting said below freezing compartment and said evaporator compartment, an above freezing evaporator located in heat transfer relation with said above freezing compartment, means providing communication between said evaporator compartment and said above freezing compartment, damper means for shutting off communication from said evaporator compartment alternately with said above freezing and below freezing compartments, fan means for forcibly circulating air alternately from said below and above freezing compartments through said evaporator compartment in heat transfer relation with said below freezing evaporator and return to said below and above freezing compartments alternately, refrigerant liquefying means operably connected to said below and above freezing evaporators, and a thermostatic control operating upon a defrosting cycle and responsive to the temperature of said cold evaporator for starting the operation of said liquefying means and moving said damper means to shut off communication with said above freezing compartment after said cold evaporator reaches a temperature'above freezing and for stopping the operation of said liquefying means and moving said damper means to shut off communication with said below freezing compartment after said cold evaporator reaches a predetermined temperature below freezing.

3. Refrigerating apparatus including insulated vertical walls and insulated horizontal walls enclosing an above freezing compartment and a below freezing compartment, one of the vertical walls adjacent the above freezing compartment being provided with an evaporator compartment and supply and return passages extending from said evaporator compartment to said above and below freezing compartments, a cold evaporator located in said evaporator compartment, a second evaporator upon one of the vertical walls in the above freezing compartment, a

refrigerant liquefying means operably connected to said evaporators and operable to cool said cold evaporator to below freezing temperatures and to cool said second evaporator to above freezing temperatures, damper means having a first alternate position for shutting olf communication between said evaporator compartment and said below freezing compartment and a second position for shutting off communication between said evaporator compartment and said above freezing compartment, fan means for circulating air through said evaporator compartment and said passages and said below and above freezing compartments in accordance with the position of said damper means, and control means having one position for operating said liquefying means to cool said cold evaporator to below freezing temperatures to cause frost to form thereon and to cool said second evaporator to above freezing temperatures and setting said damper means in said second position and having another position for stopping the operation of said liquefying means and setting said damper means in said first position to cause the circulation of air between said above freezing compartment and said evaporator compartment to quickly defrost said cold evaporator.

4. Refrigerating apparatus including insulated vertical walls and insulated horizontal walls enclosing an above freezing compartment and a below freezing compartment, one of the vertical walls adjacent the above freezing compartment being provided with an evaporator compartment and supply and return passages extending from freezing compartments, a cold evaporator located in said evaporator compartment, a second evaporator upon one of the vertical walls in the above freezing compartment, a refrigerant liquefying means operably connected to said evaporators and operable to cool said cold evaporator to below freezing temperatures and to cool said second evaporator to above freezing temperatures, damper means having a first alternate position for shutting oflE communication between said evaporator compartment and said below freezing compartment and a second position for shutting oif communication between said evaporator compartment and said above freezing compartment, fan means for circulating air through said evaporator compartment and said passages and said compartments in accordance with the position of said damper means, and control means having one position for operating said liquefying means to cool said cold evaporator to below freezing temperatures to cause frost to form thereon and to cool said second evaporator to above freezing tempera.- tures and setting said damper means in said second position and having another position for stopping the operation of said liquefying means and setting said damper means in said first position to cause the circulation of air between said above freezing compartment and said evaporator compartment to quickly defrost said cold evaporator, a second fan means for circulating air from said above freezing compartment into heat transfer with said said evaporator compartment to said above and below 30 second evaporator, said control means having means effective in said another position for stopping said second fan means during the defrosting of the cold evaporator.

References Cited in the file of this patent UNITED STATES PATENTS 2,812,642 Jacobs Nov. 12, 1957 2,863,300 Murphy et a1. Dec. 9, 1958 2,866,323 Candor Dec. 30, 1958