US3248894A - Refrigeration apparatus - Google Patents

Description

y 1966 P. F. HARBOUR 3,248,894

REFRIGERATION APPARATUS Filed Feb. 8, 1965 2 Sheets-Sheet 1 I E I! g SWITCH s3 2 IO CLOSES AT E. THIS TEMPERATURE |O I I I I I I I I I o 2 3 4 5 s 7 s 9 TIME (MINUTES) WITNESSES INVENTOR Philip E Harbour j BY ' ATTORNEY P. F. HARBOUR REFRIGERATION APPARATUS May 3, 1966 2 Sheets-Sheet 2 Filed Feb.

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United States Patent 3,248,894 REFRIGERATIQN APPARATUS Philip F. Harbour, Columbus, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Feb. 8, 1965, Ser. No. 431,025 2 Claims. (Cl. 62-156) This invention relates to refrigeration systems, more particularly to single evaporator refrigeration systems for use in domestic referigerator-freezer cabinets.

Recently the trend in refrigerator design has been to producing a refrigerator-freezer cabinet in which the appearance of frost is eliminated from both the freshfood compartment and the freezer compartment. Generally, this is accomplished by the circulation of air over an evaporator disposed outside of the compartments with the frost collecting on the evaporator and with the cooled air from the evaporator passed through the various compartments. Frost is removed from the evaporator either by the introduction of warm refrigerant into the evaporator or by applying external heat to the evaporator through the use of electrical resistance heaters, or by a combination of these two means.

In such refrigeration systems there is an energy input to the system to cool the various compartments and a second energy input to the system to heat the evaporator for defrost purposes. In other words, the system must be capable of producing both a cooling cycle to provide heat exchange in the various compartments and a heating cycle to provide heat exchange at the evaporator.

Prior systems such as those just discussed wherein heat is removed from the apparatus by refrigerating means and then heat is supplied to the apparatus to remove the frost which has accumulated on the evaporator, are uneconomical both with respect to operation and manufacture.

The present invention has as an object to provide a multiple level refrigerating system of the single evaporator type in which the heating cycle is eliminated.

A further object of the invention is to improve a refrigeration system for a domestic refrigerator-freezer wherein, when the refrigerating apparatus is operating, that is, the compressor is energized and refrigerant is supplied to the evaporator, air is passed over the evaporator and then directed through a below-freezing compartment and continuously returned to the evaporator region until such time as the temperature in the belowfreezing compartment has reached the desired degree. Thereafter, with the compressor shutdown, air from the above-freezing compartment is continuously circulated over the evaporator and thence back to the above-freezing compartment until the frost which has accumuulated on the evaporator during operation of the refrigerating cycle has been melted. Thus, during this melting or defrost portion of the cycle the necessary features and results are obtained without operation of the refrigerating system but merely by the circulation of air thereover. Inasmuch as this circulated air utilized to defrost the evaporator is taken from the above-freezing compartment, no external source of heat need be added to melt the frost from the evaporator and the refrigeration system need not be operated in order to suitably cool the abovefreezing compartment, under normal operating conditions, since the air circulated from the above-freezing compartment, over the evaporator and back to above freezing compartment gives up heat as it passes over the evaporator to melt the frost thereon and consequently the temperature in the above-freezing compartment is correspondingly lowered. Such a refrigeration system is disclosed in application Serial No. 431,023, filed Feb.

3,248,894 Patented May 3, 1966 "ice 28, 1965, filed concurrently with this application by John A. McLean, and assigned to the assignee of this application.

In the copending McLean application there is disclosed a domestic refrigerator-freezer having a freezer compartment and a fresh-food compartment separated by a third compartment in which is located a single evaporator for refrigerating both the freezer compartment and the fresh-food compartment.

The evaporator compartment is provided with an inlet thereto from the freezer compartment and an outlet therefrom to the freezer compartment and similarly is provided with an inlet thereto from the above-freezing compartment and an outlet therefrom to the above-freezing compartment. There is also disclosed a damper construction and means for adjusting the dampers so that, when the compressor is operating and the evaporator is chilled so that air flowing thereover is refrigerated, the first two mentioned openings are open for flow of air from the freezer compartment to the evaporator compartment, in heat exchange relationship with the evaporator, and back to the freezer compartment in a continuous flow, thereby cooling the refrigerator compartment. At the same time, the openings to and from the above-freezing compartment are maintained closed by their dampers until such time as the control mechanism provided therefor shuts oif the compressor, where-upon the positions of the four dampers are reversed for shutting off flow of air between the freezer compartment and the evaporator compartment and establishing flow of air between the above-freezing compartment and the evaporator compartment.

During this portion of the cycle, which is referred as a defrost portion, relatively warm air from the abovefreezing compartment flows in heat exchange relation with respect to the evaporator to melt from the latter any frost which has accumulated thereon during its last operating cycle. Not only does the warm air from the above-freezing compartment melt any accumulated frost from the evaporator, but also such air is chilled due to its contact with the evaporator with the result that the temperature within the above-freezing compartment is lowered to a desirable level.

While the operation of the apparatus disclosed in the above-identified McLean application it is entirely satisfactorily under normal operating conditions, for example, with an ambient temperature of say 70 B, there may not be sufficient cooling of the fresh-food compartment when the ambient temperature is around to F.

This present application discloses means for providing the additional refrigeration necessary to maintain the temperature of the fresh-food compartment at a satisfactory lower level during such periods of high ambient temperature.

In accordance with the present invention, the system disclosed in the McLean application is supplemented by the provision, in the evaporator compartment, of -a temperature sensing bulb or other corresponding device which, as long as the air coming from the fresh-food compartment to the evaporator chamber is above a predetermined temperature level, maintains in open position a switch which interrupts the normal electrical circuit to the damper operating motor. As long as this damper operating motor is unable to function, the dampers will remain in a position where the air flows from the evaporator to the fresh-food compartment, even after the control mechanism has called for starting of the evaporator compressor. Therefore, there is provided for the fresh-food compartment a further period of cooling which continues until such time as the control senses the desired low temperature in the fresh-food compartment.

3 Thereafter, the control closes the switch which has been interrupting the circuit to the damper operating motor, with the result the damper positions are shifted so that air now passes from the chilled evaporator to and through the freezer compartment rather than to and through the fresh-food compartment.

Accordingly, it is a further object of the present invention to provide, in a system of the type disclosed in the McLean copending application, means for insuring maintenance of a desired low temperature in the above-freezing compartment regardless of the existence of special conditions such as, for example, abnormally high amlbient temperatures, etc.

These and other objects, features and advantages of the invention will appear more fully from the following detailed description, taken in connection with the accompanying drawings forming a part of the application, in which:

FIGURE 1 is a rear elevational view, partially in section, of a refrigerator freezer cabinet having the invention employed therein and showing air flow through the compartments;

FIG. 2 is a vertical sectional view of a portion of the cabinet of FIG. 1 taken on an enlarged scale to show the invention in detail; and,

FIG. 3 is a curve of temperature versus time plotted from test results showing the rate of temperature decrease at the evaporator inlet during compressor operation for two widely differing ambient temperatures.

Referring to the drawings, especially FIGS. 1 and 2, there is shown a refrigerator-freezer cabinet having walls defining a top positioned freezer compartment 11 and a bottom positioned above-freezing compartment 12, these two compartments being sometimes referred to as a below-freezing temperature compartment 11 and an above-freezing temperature compartment 12. Between the freezer compartment 11 and the above-freezing compartment 12, and preferably adjacent the rear of the cabinet 10, there is disposed an evaporator compartment 13 containing a refrigerant evaporator 14. The refrigerant evaporator 14 is of the finned tube type, and is connected into a refrigerating system of the compressorcondenser-evaporator type. The refrigerating system is not shown in its entirety and may be of any type well known in the art, and the details are not shown since they form no part of the present invention.

The evaporator compartment 13 is provided with a pair of outlet openings 16 and 17 at one side thereof communicating with the freezer compartment 11 and the above-freezing compartment 12, respectively. At the opposite side of the evaporator compartment 13 there is provided a pair of inlet openings 18 and 19 likewise communicating with the freezer compartment 11 and the above-freezing compartment 12, respectfully. Flow control means includes a single damper 47 adjacent the outlet side of the evaporator compartment 13, movable from the position shown in which outlet 16 is closed and outlet 17 is open, to the dot dash position shown wherein output 17 is closed and outlet 16 is open. At the inlet side of the evaporator compartment 13 a damper 48 similar to damper 47 is provided and functions in a like manner to move from the position shown, in solid lines, in which inlet 18 is closed and inlet 19 is open, to the dot dash line position in which inlet 19 is closed and inlet 18 is opened. The dampers 47 and 48 are retained on link members 49 and 51 respectively. The link members 49 and 51 have their outer ends pivotally connected to actuating rods 52 and 53 respectively, each having an end thereof pivotally connected to a crank arm 54 at a pin 56. Crank arm 54 is mounted to the drive shaft 43 of a damper drive motor 44 and is rotated unidirectionally.

In FIG. 2 there is shown a schematic circuit diagram which is applicable to the system disclosed in the copending McLean application. The circuit of FIG. 2 provides a temperature sensing element in the form of a control bulb 59 located in the evaporator compartment 13 in the path of outlet air flowing from the compartment. The control bulb 59 is connected to a thermostatic element 61 controlling a single throw switch 62 in the circuit. A second single pole switch 63 is controlled by thermostat 64 oppositely connected to a temperature sensing bulb 66 located in the compartment 13, preferably in close proximity to the refrigerant inlet tube of the evaporator 14.

The circuit furnishes power to a motor compressor 67 forming part of the refrigeration system, and to the damper drive motor 44. One wire connecting the motor 44 in the circuit is also connected to a snap action single pole double throw switch 68 which is actuated by a cam 69 connected to the drive shaft 43 of the damper drive motor. The snap acting switch 68 is biased toward the cam surface to snap one way as the rise on the cam engages it and 180 later to snap the other way, as it falls off the rise in the cam and rides along the flat side of the latter.

An electric fan 46 is connected into the circuit through loop which includes a single pole switch 71 which remains closed when the refrigerator door is in the closed position and is biased open when the refrigerator door is in an open position. Both the major refrigeration circuit loop and the loop containing the blower or fan 46 are connected across a pair of supply lines L1 and L2 which may be any standard volt house current outlet.

The circuitry as disclosed by Mr. McLean in his copending application did not include the control bulb 66, the thermostatic device of the switch 63. These -features have been added to the McLean construction or system by applicant to effect the object of the present invention.

With respect to the operation of this device, first assume that the three parts just mentioned, identified as 66, 64 and 63 of FIG. 2, are not present in the circuit. With the switch 71 closed and the dampers 47 and 48 closing the openings 16 and 18 to the freezer compartment 11, the air is circulated from the above-freezing compartment 12 through the open-ing 19 into the evaporator compartment 13 where it flows over the chilled and usually frosted evaporator and discharges through the opening 17 back to the above-freezing compartment. Due to the air being drawn across the evaporator 14, and thereby chilled, switch 62, which is set to close at a relatively high temperature, is maintained in an open position and the compressor 67 is not operating. During this cycle, the air leaving the evaporator is gradually warming due to the shutdown of the compressor 67 and the melting of any frost formed on the evaporator 1'4. The water resulting from melting of frost or ice on the evaporator may be carried from the evaporator compartment to a point of disposal by any suitable means (not shown).

The temperature sensing bulb 59 and the thermostat 61 are so calibrated that when a temperature in the range of from 35 Fahrenheit to 40 Fahrenheit is sensed by the bulb, the switch 62 is closed. Closing of the switch 62 places a line potential across the compressor motor 67 and the damper motor 44, thereby initiating operation of both electrical devices. The damper motor 44 operates through a turn of the shaft 43, thereby moving the dampers 47 and 48 to positions where their operation is reversed in that the openings 16 and 18 are opened and the openings 17 and 19 are closed. At the end of the 180 turn of the shaft 43, the switch 68 will move from the high side of the cam 6-9 to the low side thereof and consequently moves from the contact point 72 to the contact point 73.

The compressor 67 continues to operate and to lower the temperature of the evaporator 14, while the blower 46 circulates air through the freezer compartment 11 from the evaporator 13, thereby cooling the freezer compartment. During this cycle frost may form on the evaporator 14. However, when the temperature sensed by the bulb 59 drops to with-in a range of zero degrees Fahrenheit to 5 Fahrenheit the thermostat 6-1 actuates the switch 62 to the opened position. With the switch 62 in the open position a line potential is established across the damper motor 44 and the shaft 43 again turns 180, moving the switch 68 from the contact 73 to the contact 72, and correspondingly moving the dampers 47 and 48 to a position closing off the freezer compartment 11 from the evaporator compartment 13 and establishing communication between the above-freezing compartment 12 and the evaporator compartment. With the switch 68 connected to the contact 72 and switch 62 open, the compressor 67 is shut off and the defrost cycle, with which this description of operation started) again begins, during which the above-freezing compartment is cooled and the evaporator deiced or defrosted.

The cycling and control as just described is inherent in the disclosure of the -M'cLean application Serial No. 431,023, filed Feb. 28, 1965 and does not include the present invention.

As indicated earlier in the specification, the system just described operates, satisfactorily under most operating conditions, but under extreme conditions of operation, for example, with an ambient temperature around 100 to 110, there may not be sufficient cooling of the fresh-food compartment during the normal defrost-ing of the evaporator. Accordingly, applicant has modified the control system just described and proposed by Mr. Mc- Lean in his copending application by adding thereto the control bulb 66, the thermostatic device 64 and the switch 63.

Assuming now that these three above-mentioned elements have been added to the circuitry disclosed by McLean and as now illustrated in FIG. 2, and that the freshafood compartment is being cooled and the evaporator defrosted as previously discussed, then when the temperature of the control bulb 59 is raised to a predetermined temperature in the range of 35 Fahrenheit to 40 Fahrenheit, the switch 62 will be closed. However, should the air being returned from the fresh-food compartment be at an abnormally and undesirably high temperature, then the control bulb 66 will be effected thereby with the result that the switch 63 will be held in an open position. With the switch 63 in the open position, only the compressor 67 is activated and the damper drive motor is not energized to move the dampers to the position closing the openings 17 and 19. Consequently, as the evaporator 14 is lowered in temperature, cooler air is circulated through the fresh-food compartment to bring it to the desired temperature. In other words, the switch over from defrosting to refrigeration is not accompanied by a corresponding shitting of the dampers to direct air flow through the freezer compartment rather than the fresh-food compartment and consequently cooling of the fresh-food compartment continues even though the compressor is now operating.

The control bulb 66 and thermostat 64 are so calibrated that when the bulb 66 senses a temperature within the range of from 5 to 15 Fahrenheit, the thermostat actu'ates the switch 63 to close the circuit to the drive motor 44. The damper drive motor then operates through a 180 turn of the shaft 43 to move the dampers to the position closing openings 17 and 19 and opening the openings 16 and 18, thereby directing flow of cooling air to the freeze-r compartment. By employing a thermostat 64 which opens the switch 63 in a temperature range of 20 to 30 Fahrenheit, and closing the switch in the temperature range as previously mentioned, a suitable time delay is established during which the evaporator 14 is being lowered in temperature while air is being circulated through the fresh-food compartment 12.

In this connection, reference should be had at this point to FIG. 3 of the drawing where there is shown a temperature curve plotted from the operation of a unit in the manner described. The temperatures plotted are taken at that portion of the evaporator which the control bulb 66 is located. During operation of the unit in the 70 Fahrenheit ambient, with the control bulb and thermostat 64 calibrated to close the switch 63 at a 10 Fahrenheit temperature, the change in damper locations is delayed approximately one minute after the compressor operation commences. (Note that the lower curve marked 70 ambient has crossed the 10 Fahrenheit line in slightly less than one minute of time.) This is generally a sufficient period of time to cool the fresh-food compartment due to the small amount of leakage of heat into the compartment at the relatively low ambient.

However, with an ambient of, for example, Fahrenheit, it will be observed that the closing of switch 63 and hence of the dampers is delayed for approximately six minutes. (Note that the upper curve marked 110 ambient crosses the 10 temperature line at approximately six minutes on the chart of FIG. 3). This time delay is sufficient to bring the firesh-food compartment 12 to the desired low temperature under the relatively high ambient conditions.

During operation of the refrigeration system as described above, the switch 61 remains in a closed position and the fan 46 is continuously operating whether the dampers are set to supply air to the freezer compartment 11 or to the fresh-food compartment 12. However, the switch 71 is so arranged that, should the cabinet door he opened at any time, the circuit to the fan 46 is interrupted, thereby assuring that cool air within either of the refrigerated spaces or compartments is not forced out into the room to be replaced by warm or moist air therefrom due to the door being open.

It is believed clear from the above description that applicant has contributed to the system disclosed by McLean in his copending application Serial No. 431,023, filed Feb. 28, 1965, a desirable feature which extends the area of practical use of the McLean system.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible to various changes and modifications without departing from the spirit thereof.

I claim as my invention:

1. In apparatus having a freezing compartment and an above-freezing compartment, a refrigeration system for said compartment including a compressor, a condenser and an evaporator, means defining a compartment for said evaporator, said evaporator compartment having an inlet thereto from the freezer compartment and an outlet therefrom to said freezer compartment and having an inlet thereto from the above-freezing compartment and an outlet therefrom to said above-freezing compartment, means for controlling flow of air through said evaporator compartment inlets and outlets, means for adjusting said control means from a first position wherein the inlet and outlet communicating with the freezer compartment are open and the inlet and outlet communicating with the abovefreezing compartment are closed to a second position wherein the inlet and outlet communicating with the freezer compartment are closed and the inlet and outlet communicating with the above-freezing compartment are open, said adjusting means under normal conditions of ambient temperature providing for operation of the compressor to chill the evaporator when the control means is in said first position and preventing operation of said compressor when said control means is in said second position, said adjusting means including means operable under conditions of abnormal ambient temperature to cause operation of the compressor when the control means is in said second position while the temperature of air in said above-freezing compartment is above a predetermined desired level.

2. In apparatus having a freezing compartment and an 7 above-freezing compartment, a refrigeration system for said compartments including a compressor, a condenser and an evaporator, means defining a compartment for said evaporator, said evaporator compartment having an inlet thereto from the freezer compartment and having an outlet therefrom to said freezer compartment and having an inlet thereto from the above-freezing compartment and an outlet therefrom to said above-freezing compart ment, damper means for controlling flow of air through said evaporator compartment inlets and outlets, control means for adjusting said damper means from a first position wherein the inlet and outlet communicating with the freezer compartment are open and the inlet and outlet communicating with the above-freezing compartment are closed to a second position wherein the inlet and outlet communicating With the freezer compartment are closed and the inlet and outlet communicating with the abovefreezing compartment are open, means for translating air through said evaporator compartment in heat transfer relation to said evaporator, said control means under normal conditions of ambient temperature providing for operation of the compressor to chill the evaporator When the damper means is in said first position and preventing operation of said compressor when said damper means is in said second position, said control means including means operable under conditions of abnormal ambient temperature to cause operation of the compressor when the damper means is in said second position while the temperature of air in said above-freezing compartment is above a predetermined desired level.

References Cited by the Examiner UNITED STATES PATENTS 3,107,501 10/1963 Stickel 62-156 3,126,716 3/1964 De Witte 62-187 3,174,297 3/1965 Kuhn 62156 WILLIAM J. WYE, Primary Examiner.

Claims (1)

1. IN APPARATUS HAVING A FREEZING COMPARTMENT AND AN ABOVE-FREEZING COMPARTMENT, A REFRIGERATANT, SYSTEM FOR SAID COMPARTMENT INCLUDING A COMPRESSOR, A CONDENSER AND AN EVAPORATOR, MEANS DEFINING A COMPARTMENT FOR SAID EVAPORATOR, SAID EVAPORATOR COMPARTMENT HAVING AN INLET THERETO FROM THE FREEZER COMPARTMENT AND AN OUTLET THEREFROM TO SAID FREEZER COMPARTENT AND HAVING AN INLET THERETO FROM THE ABOVE-FREEZING COMPARTMENT, MEANS LET THEREFROM TO SAID ABOVE-FREEZING COMPARTMENT, MEANS FOR CONTROLLING FLOW OF AIR THROUGHN SAID EVAPORATOR COMPARTMENT INLETS AND OUTLETS, MEANS FOR ADJUSTING SAID CONTROL MEANS FROM A FIRST POSITION WHEREIN THE INLET AND OUTLET COMMUNICATING WITH THE FREEZER COMPARTMENT ARE OPEN AND THE INLET AND OUTLET COMMUNICATING WITH THE ABOVE FREEZING COMPARTMENT ARE CLOSED TO A SECOND POSITION WHEREIN THE INLET AND OUTLET COMMUNICATING WITH THE FREEZER COMPARTMENT ARE CLOSED AND THE INLET AND OUTLET COMMUNICATING WITH THE ABOVE-FREEZING COMPARTMENT ARE OPEN, SAID ADJUSTING MEANS UNDER NORMAL CONDITIONS OF AMBIENT TEMPERATURE PROVIDING FOR OPERATING OF THE COMPRESSOR TO CHILL THE EVAPORATOR WHEN THE CONTROL MEANS IS IN SAID FIRST POSITION AND PREVENTING OPERATION OF SAID CONPRESSOR WHEN SAID CONTROL MEANS IS IN SECOND POSITION, SAID ADJUSTING MEANS INCLUDING MEANS OPERABLE TO CAUSE CONDTIONS OF ABNORMAL AMBIENT TEMPERATURE TO CAUSE OPERATION OF THE COMPRESSOR WHEN THE CONTROL MEANS IN SAID SECOND POSITION WHILE THE TEMPERATURE OF AIR IN SAID ABOVE-FREEZING COMPARTMENT IS ABOVE A PREDETERMINED DESIRED LEVEL.

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