US3159980A - Refrigerator including combination evaporator fan motor and defrost control - Google Patents

Description

Dec. 8, 1964 D. A. SOLLEY, JR 3,159,930

REFRIGERATOR INCLUDING COMBINATION EVAPORATOR FAN MOTOR AND DEFROST CONTROL Filed July 17, 1963 SUPPLY LINES INVENTOR.

DOUGLAS A SOLLEY. TR.

515% 2 H\ ATT RNEY F'IG.3

United States Patent 3,159,930 REFRIGERATOR INCLUDING CGMBINATIGN EVAPGRATGR FAN MOTOR AND DEFRGST CON'lROL Dougm A. Solley, Era, Fern Creek, Ky, assignor to General Electric Company, a corporation of New York Fiied Italy 17, 1963, Ser. No. 2%,e61 3 Qlaims. (Cl. 62155) The present invention relates to refrigerators of the type in which at least one compartment is maintained at the desired refrigerating temperatures by means of an air stream circulated over an evaporator positioned outside of or separate from the compartment and is particularly concerned with a refrigerator of this type including a combination fan and defrost control including a single drive motor.

Various refrigerators are known in which the storage compartment has been maintained at the desired refrigerating temperature by the forced circulation of air over an evaporator disposed outside of the compartment and through the compartment. By positioning the evaporator otuside the compartment, it may be periodically warmed to defrosting temperatures Without substantially afiecting the storage temperatures within the compartment. During the defrost operation of the evaporator, the fan for circulating air is de-energized and the present invention is particularly concerned with a forced air cooled refrigerator in which the fan motor also provides means for operating the defrost control means.

A primary object of the invention is to provide a forced air cooled refrigerator including a storage compartment, an evaporator positioned outside of the compartment, a fan for circulating air from the compartment over the evaporator and a defrost control means operated by the fan motor for controlling the periodic defrosting of the evaporator.

Another object of the invention is to provide a forced air cooled refrigerator including an evaporator disposed outside of the refrigerator storage compartment, a motor driven fan for circulating air over the evaporator and through the compartment and defrost control means dis posed in the relatively dry portion of the circulating air stream downstreamfrorn the evaporator. 1

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 part of this specification.

In accordance with one embodiment of the present invention, there is provided a refrigerator including a storage compartment, an evaporator disposed outside of that compartment and a duct defining an air flow passageway outside of the compartment for the circulation of air from the compartment over the evaporator. A fan is provided at the outlet end of the duct and means are provided for energizing the motor driving the fan only when refrigerant is being supplied to the evaporator. A defrost control means for initiating periodic warming of the evaporator to defrosting temperatures is driven by the fan motor so that the evaporator is periodically defrosted as a function of the fan motor running time. In the preferred embodiment of the invention, the combination fan, fan motor and defrost control means is disposed in the path of the air flowing from the evaporator to the storage compartment which air is relatively free from moisture.

For a better understanding of the invention reference may be had to the accompanying drawing in which:

FIGURE 1 is a side elevational view of a refrigerator cabinet embodying the present invention;

FIGURE 2 is an enlarged sectional view of a portion of the cabinet illustrated in FIGURE 1;

FIGURE 3 is a schematic illustration of a refrigerating system employed for refrigerating the cabinet of FIG- URE 1; and

FIGURE 4 is a sectional view taken generally along line 44 of FIGURE 2. v

While the invention is applicable to refrigerators containing one or more storage compartments, it will be described with specific reference to a refrigerator comprising a single storage compartment cooled by the forced circulation of air over an evaporator disposed outside of that compartment.

With reference to FIGURE 1 of the drawing, there is shown an embodiment of the present invention in the form of a household refrigerator including a storage compartment 1 defined by a plurality of insulated walls including a rear wall 2, the access opening to the compartment being closed by a door 3. The compartment 1 is maintained at desired refrigerating temperatures by means of a single evaporator 4 positioned in the insulated rear wall 2 of the cabinet. Condensed refrigerant is supplied to the evaporator 4 from a condensing unit positioned in the lower portion of the cabinet and including a compressor 5 and a condenser 6.

More specifically the evaporator 4 is disposed in an enlarged portion of a duct '7 having an inlet opening 8 communicating with the lower portion of the storage compartment 1 and an outlet 9 at the upper end of the duct. A fan 1% driven by a motor 11 is disposed in the outlet end of the duct 7 and is designed to draw air upwardly through the duct 7 over the evaporator 4 to discharge the cooled air into the storage compartment 1.

A suitable automatic defrost refrigerating system is shown schematically in FIGURE 3 of the drawing. In addition to the evaporator 4, the compressor 5 and the condenser 6, the system includes a capillary flow restrictor 12 connecting the outlet end of the condenser 6 to the evaporator 4, these components being connected in series flow relationship so that the evaporator 5 withdraws vaporized refrigerant from the evaporator 4 through a suction line 13 and discharges high pressure refrigerant to the condenser 6 through the discharge line 14. For the purpose of periodically warming the evaporator 4 to defrosting temperatures there is provided a bypass or defrost line 15 connecting the compressor discharge line 14- to the inlet end of the evaporator 4. A normally closed defrost valve 17 provided in the line 15 and controlled by means or" a solenoid 18 is periodically opened so that hot compressed refrigerant vapor is bypassed to the evaporator through the defrost line 15 for warming the evaporator to defrosting temperatures. The valve 17 is of a construction such that whenthe bypass line 15 is open, the valve 17 also introduces a restriction into the suction line 13 controlling the flow of condensed refrigerant from the defrosting evaporator 4 back to the compressor 6.

The operation of the compressor 5 and the fan motor 11 is controlled by a control circuitry including a cold control thermostat 21 having its sensing bulb 22 positioned Within the storage compartment 1 for sensing the temperatures within that compartment. The thermostat 21 is adapted to energize both the compressor 5 and the fan motor 11 whenever the temperature within the compartment 1 is below a predetermined minimum and to de-energize the compressor and the fan motor when the compartment temperature reaches a predetermined maximum. As is shown in FIGURE 2, the compressor 5 and the fan motor 11 are connected in parallel so that the fan operates only when the compressor 5 is also energized during normal refrigerating operation of the refrigerating system.

:J In accordance with the present invention, the control circuitry also includes defrost control means for operating tained within a housing 24 which along with the fan motor 11 is disposed in the upper end of the. duct 5. The switch 23 includes a magnetic switch arm 25 movable into engagement with either a fan motor energizing contact 26 or a defrost valve energizing contact 27. As is shown in FIGURE 4 of the drawing, a magnetfid provided within the housing 24 is provided for operating the switch arm 25 from one contact to the other. More specifically, the switch 23 is of the type in which the arm 25 is spring biased into engagement with the contact 27 when the switch is not subjected to the field of the magnet 28 but is designed to be magnetically transferred into engagement with the contact 26 when the magnet 28 is brought into close proximity with the non-magnetic switch envelope 30.

The purpose of the switch 23 is to energize the fan motor 11 whenever the compressor is running under normal refrigerating operation of the refrigerator and to energize the defrost valve 17 with the compressor running during defrost operation of the refrigerator. In order to periodically initiate a defrost cycle and also time the length of that cycle, means are provided for moving the magnet 28 out of operating position relative to the switch 23 after a given period of operation of the fan motor 11 and for again establishing magnetic contact between the magnet 28 and the switch 23 after a predetermined time sufficient to insure the removal of all of the frost from the defrosting evaporator 4.

The structure of the defrost control means designed to accomplish these results is shown in FIGURE 4 of the drawing. With reference to that figure, it will be seen that the switch 23 is secured by means of an arm 32 to one end of a bellows 35 forming part of a double bellows structure including a bellows 36. The two bellows 35 and 36 are filled with a liquid and are connected by means of a timing orifice or aperture 37. The liquid fill for the bellows may be a silicone oil, an alcohol or a similar liquid which has a freezing point lowerthan any anticipated operating condition of the control. The bellows 36 is biased to a retracted or compressed position by means of a spring 39, the compressive force of which can be ad justed by means of an adjusting screwed. When the spring compresses the bellows 36, the fluid contained within the double bellows structure is displaced into the bellows 35 so that this bellows is in turn extended.

The magnet 28 is carried on the free end of a pivoted lever arm 41 and this arm is normally biased into magnetic engagcrnentwith the switch 23 and mechanical engagement with the foot or pad 42 at the end of the bellows 35 by means of a cam 43. The cam 43 in turn is connected to the fan motor Ill through a suitable gear train (not shown) so that, for example, the cam 43 will rotate one revolution during normal operation of the fan motor 11 during a 12 hour period.

The cam 43 includes a shoulder 45 which is designed to function as a timing means and initiate a defrost cycle after one complete revolution thereof. More specifically, during normal operation of the defrost control means, rotation of the cam 43 normally maintains the magnet 28 in operating position relative to the switch 23 and also maintains the arm 41 in engagement with the pad 42 provided on the bellows 35. c As the cam rotates in a counterclockwise direction as viewed in FIGURE 4, thearm 41 is gradually moved to the right thereby slowly'compressing the bellows 35 while at the same time maintaining the magnet 28 in operative position relative to the switch 23 supported on the bellows 35 so that the fan motor is energized through that switch. After a predeterminedperiod 4 of time, the cam rotates to the point such that the arm 41 trips off of the shoulder 45' under the action of the biasing spring 46. This results in the magnet 28 being removed from operating proximity to the switch 23 whereby the switch arm 25 becomes disengaged from the contact 26 and engages the contact 27 thereby energizing the defrost valve 17. At the same time, the switch arm 41 becomes disengaged from the pad or foot 42 removing the compressive forces thereof from the bellows 35. As the bellows 35 slowly expands by the return of fiuid thereto through the aperture 37 due to the retoring spring forces of each bellows and the force of the spring 39 on the bellows 36, the switch 23 carried by the bellows 35 moves to the left until it is again positioned adjacent to the magnet 28. At this point, the switch 23 is returned to its r normal position in which the switch arm 25 is in engagement with the contact 26 thereby terminating the defrost cycle and again placing the operation of the fan motor 11 under the control of the thermostat 21. A new refrigerating cycle is thus initiated and the fan It) and compressor 5 will cycle on and off to maintain the desired temperatures within the compartment 1. Also when contact of the switch arm 25 with the contact 27 is broken, the solenoid valve 17 is de-energized so that flow of the defrost gas through the line 15 is stopped and normal refrigerant flow through the condenser 6 to the evaporator is reestablished. 7 V

The size of the orifice or opening 37 of course determines the length of the defrost cycle using any given bellows charging liquid. The exact size will depend upon the viscosity of the liquid fill for the bellows 35 and 36 under the operating conditions of the defrost control means and the amount of heat which can be supplied to the evaporator '4 during the defrost cycle. It will be understood, of course, that while a hot gas has been illustrated as means for warming the evaporator 4 to defrost temperatures, other suitable means such as electric heat may also be employed in which case the control of the heating means will be the same as that used in the control of the defrost valve 17 but the compressor 5 is also placed under this control so thatthe refrigerating efiect resulting from the operation of the compressor during the defrost cycle will not oppose the defrost action of the electric or resistance heating. However, in the preferred embodi merit of the. invention, hot gas is employed for defrosting the evaporator 4 and thecompressor 5 is operated during the defrost cycle.

It will also be apparent from the foregoing that other types of switches with suitable'mechanisms for operating them may be used instead of the hydraulic escapement and reed switch 23. For example, a mechanical escapement such as is used in clock mechanisms may be used. However, the disclosed means including a reed switch which is completely sealed within the glass or similar envelope 30 is preferred because of its simplicity and high reliability under the operating conditions prevailing in a refrigerator.

While there has been shown and described a particular embodiment of the invention it will be understood that the invention is not limited thereto and it is intended by the appended claims to cover all such changes and modifications as come within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A refrigeratoncomprising a storage compartment, an evaporator disposed outside of said compartment, condensing means including a compressor for normally supplying condensed refrigerant to said evaporator, defrost means for periodically defrosting said evaporator, a fan for circulating air from said compartment over said evaporator, a motor for driving said fan, a motor circuit for energizing said motor only when said compressor is energized to supply condensed refrigerant to said evaporator, and defrost control means including timing means driven by said motor for initiating operation of said defrost means. 7

2. A refrigerator comprising a storage compartment, an evaporator disposed outside of said compartment, defrost means for periodically warming said evaporator to defrost temperatures, condensing means including a compressor for normally supplying condensed refrigerant to said evaporator, a fan for circulating air from said compartment over said evaporator, a motor for driving said fan, a motor circuit for energizing said motor only when said compressor is energized to supply condensed refrigerant to said evaporator, and defrost control means including timing means driven by said motor for initiating operation of said defrost means, said motor and said defrost control means being disposed in the path of the air flowing from said evaporator to said compartment.

3. A refrigerator comprising insulated walls defining a storage compartment, a duct in one of said walls having the inlet and outlet ends thereof communicating with said compartment, an evaporator disposed in said duct, condensing means including a compressor for normally supplyingcondensed refrigerant to said evaporator, de frost means for periodically defrosting said evaporator, a fan in the outlet end of said duct for circulating air cooled by said evaporator through said compartment, a motor for driving said fan, a motor circuit for energizing said motor only when said compressor is energized to supply condensed refrigerant to said evaporator, defrost control means including timing means driven by said motor for initiating operation of said defrost means, 'said motor and defrost control means being disposed in said duct adjacent the outlet end thereof.

Mann Oct. 6, 1959 Jacobs Nov. 28, 1961

Claims (1)

1. A REFRIGERATOR COMPRISING A STORAGE COMPARTMENT, AN EVAPORATOR DISPOSED OUTSIDE OF SAID COMPARTMENT, CONDENSING MEANS INCLUDING A COMPRESSOR FOR NORMALLY SUPPLYING CONDENSED REFRIGERANT TO SAID EVAPORATOR, DEFROST MEANS FOR PERIODICALLY DEFROSTING SAID EVAPORATOR, A FAN FOR CIRCULATING AIR FROM SAID COMPARTMENT OVER SAID EVAPORATOR, A MOTOR FOR DRIVING SAID FAN, A MOTOR CIRCUIT FOR ENERGIZING SAID MOTOR ONLY WHEN SAID COMPRESSOR IS ENERGIZED TO SUPPLY CONDENSED REFRIGERANT TO SAID EVAPORATOR, AND DEFROST CONTROL MEANS INCLUDING TIMING MEANS DRIVEN BY SAID MOTOR FOR INITIATING OPERATION OF SAID DEFROST MEANS.

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