US2468105A - Absorption refrigerating system, including a defrosting arrangement and a control theefor - Google Patents

Description

P" 1949- s. w. E. ANDERSSON 2,463,105

. ABSORPTION REFRIGERATING SYSTEM, INCLUDING A DEFROSTING ARRANGEMENT AND A CONTROL THEREFOR Original Filed lay 3, 1945 3 Shasta-Sheet 1 INVENTOR ATTORNEY A 1949. s. w. E. ANDERSSON 2,468,105

' ABSORPTION REFRIGERATING' SYSTEM, INCLUDING A DEFROSTING ARRANGEMENT AND I A CONTROL THEREFOR Original Fi led May 3, 1945 3 Sheets-Sheet '2 INVENTOR j 'vwaanm ATTORNEY 3 snets-sneet a INVENTOR ORNEY A DEFROSTING ARRANGEMENT AND A CONTROL THEREFOR \\\\\\\\\&

M-WtQw-W f ATT April 1949- s. w E. ANDERSSON ABSORPTION REFRIGERATING SYSTEM, INCLUDING ori inal Filed my a, 1945 evaporator.

Patented Apr. 26,1949

, ABSORPTION REFRIGERATING SYSTEM,

INCLUDING A ,DEFROSTING ARRANGE,- MENT AND A CONTROL THEREFOR Sven W. E. Andersson, Evansville, Ind., assignor to Serve], Inc, New York, N. Y., a corporation of Delaware Continuation of application Serial No. 591,753,

May 3, 1945.

1948, Serial No. 57,876

16 Claims. (Cl. 62-5) My invention relates to refrigeration and particularly to control devices for domestic refrigerators. More particularly, my invention relates to defrosting" controls for domestic refrigerators of the unipressure absorption type.

This application is a continuation of and relates back for common subject matter to my earlier application Serial No. 591,753, filed May 3, 1945, now abandoned.

In domestic refrigerators provided with a low temperature evaporator or cooling element for freezing ice cubes and a high temperature evaporator for cooling the food storage compartment,

it is necessary to operate the low temperature.

evaporator at a temperature well below the freezing point of water and, due to the presence of water vapor in the air which comes in contact with this low temperature evaporator, moisture condenses and congeals on the surface of the low temperature evaporator. This congealed moisture produces a layer of frost or ice which gradually accumulates and decreases the efficiency of the refrigerator. This accumulated frost is undesirable also from the standpoint of sanitation. The high temperature evaporator, on the other hand, operates at a temperature above the freezingpoint of water; therefore, moisture does not congeal on the high temperature evaporator. With the type of refrigerators above referred to, it is desirable that the low temperature evaporator be defrosted without interfering with the normal operation of the high temperature Also, since the rate of accumulation of frost on the low temperature evaporator varies under diflerentconditions of operation, and since it is not always convenient to interrupt operation of the low temperature evaporator in order that it may be defrosted, it is desirable that defrosting may be started voluntarily. However, it is desirable that the refrigerator be automatically returned to normal operation after the frost or ice has been removed from the low temperature evaporator.

This application November 2,

evaporator without interrupting the production of refrigeration by another evaporator. This control further includes an arrangement whereby a. single conveniently-located dial is utilized for manually'initiating a, defrosting .cycle for one evaporator and for adjusting the temperature at which another evaporator shall operate.

These and other objects and advantages of my invention will be apparent from the, following description taken in connection with the accompanying drawings, wherein like reference numerals are used to designate like parts throughout the different views and wherein:

Fig. 1 illustrates more or less diagrammatically a refrigerating system incorporating my improved control;

Fig. 2 is a broken view in front elevation of a refrigerator, partly in section, showing the cooling elements and a, dual control incorporating my invention;

Fig. 3 is a; side view, partly in vertical section, of the arrangement illustrated in Fig. 2;

Fig. 4 is an enlarged horizontal sectional view of a part of the control device illustrated in Figs. 2 and 3;

Fig. 5 is a front view of the housing of the control device illustrated in Fig. 4.

Referring particularly to Fig. 1 of the drawing, there is illustrated an absorption refrigerating system of the unipressure type provided with a rapid defrosting device with which my improved dual control is adapted to be incorporatecl. This particular refrigerating system is not my invention, but is the invention of Benjamin A. Phillips andis described and claimed in his copending application Serial No. 591,609, filed May 2, 1945. This system includes a generator H], a rectifier l I, a condenser l2, an evaporator l3, a gas heat exchanger M, an absorber I5 and a liquid heat exchanger Hi all interconnected in a manner well known in the art which will be described more in detail hereinafter. The

I have invented a control for a refrigerator having a plurality ofcompartments maintained at distinctly different temperatures. This control includes mechanism whereby an evaporator for cooling one of the compartments may be defrosted while refrigerationv is continuously produced ,by another evaporator for maintaining another of the compartments at substantially constant temperature. This control also includes means whereby the defrosting cycle of one evaporator is manually initiated and automatically stopped responsive to the temperature of said one system is charged with a, solution of refrigerant and absorption liquid, and with a pressure-equalizing gas which is inert with respect to the refrig- "erant and absorption liquid. It is preferred to use ammonia as the refrigerant, water as the absorb-. cut, and hydrogen as the inert pressure-equalizmg gas.

The cooling element or evaporator l3 includes an upper or low temperature section l3a located in a, freezing compartment l8 of a thermallyinsulated refrigerator cabinet 20 and a lower or high temperature section l3b located in a food storage compartment 22 of the refrigerator cabtering through vapor lift duits 38 and 32 into the upper portion of low temperature section I8a of the evaporator where it evaporates and diffuses into weak inert gas flowing into said evaporator section through a conduit 84 connected to gas heat exchanger I4, thereby producing a desired refrigerating effect. The enriched inert gas along with liquid refrigerant flows from low temperature section I3a through conduit I3c to high temperature section .I3b where additional refrigerant vaporizes and diffuses into the inert gas producing additional refrigeration, but at a higher temperature. The resulting gas mixture of refrigerant and inert gas flows from evaporator section I3b through a conduit 36, inner passage 38 of gas heat exchanger I4, a conduit 48 and a vessel 4| into the lower portion of absorber I5.

In absorber I5 refrigerant vapor is absorbed by absorption liquid which enters the upper portion of the absorber through a conduit 42. The inert gas stripped of refrigerant vapor flows from the upper portion of the absorber, through outer passage 44 of gas heat exchanger I4 and conduit 34 back to low temperature evaporator section I3a to complete the inert gas circuit. The circulation of inert gas between the evaporator and absorber is due to the difference in specific weight of the column of inert gas rich in refrigerant flowing from evaporator section I3b to the absorber and the column weak in refrigerant vapor flowing from the absorber to evaporator section I 3a. The column of inert gas rich in refrigerant vapor being heavier than that weak in refrigerant, a force is produced which causes circulation of inert gas through and between the evaporator sections and the absorber.

Absorption liquid enriched in refrigerant flows from the lower portion of absorber I5 into and through vessel 4I, through a conduit 46, inner passage 48 of liquid heat exchanger I6 and a vapor lift pump 58 into generator I8. A flue 52 extends axially and concentrically through generator I8,

and is arranged to be heated by any suitable means such, for example, as a gas burner 54. As shown, the lower portion of vapor lift pump 58 is coiled about and is in intimate heat exchange relation with'thelower portion of flue 52. Refrigerant vapor is expelled from the refrigerant-absorbent solution in generator I8 due to heating by burner 54, and this vapor together with vapor enpump 58, flows through rectifier II, a conduit 58 and a liquid trap 58 into the upper portion of condenser I2. In passing through the rectifier any water vapor which may have been expelled from the generator with the refrigerant vapor is condensed and flows back to the generator. The refrigerant vapor is condensed and flows back to the generator. The refrigerant vapor is condensed in condenser I2 and the liquefied refrigerant is returned to the upper evaporator section through conduits 38 and 32 to complete the refrigerant circuit.

The absorption liquid which has been weakened by expulsion of refrigerant therefrom flows 4 conduit 68, outer passage 82 of liquid heat ex changer I6 and conduit 42 back to the upper portion of absorber I5 completing the absorption liquid circuit. The circulation of absorption liquid results from raising liquid into the generator by vapor lift action through pump 58. The heat produced in the absorber by the absorption of refrigerant vapor into absorption liquid may be transferred from the absorber by any suitable means such, for example, as by air-cooled heat transfer fins 84.

The outlet end of condenser I2 is connected by a conduit 86, a pressure vessel 68 and a conduit 18 to a part of the inert gas circuit, as at the upper end of gas heat exchanger I4, for example, so that any inert gas which passes through the condenser may flow back to the gas circuit. Refrigerant vapor not liquefied in the condenser flows through conduit 88 and into vessel 68, displacing inert gas therefrom and forcing said gas through conduit I8 into the gas circuit. In this manner, the total pressure in the entire system is increased to insure continuous refrigeration. The supply of fuel gas to burner 54 is controlled by a thermostatically-operated valve 84v to be described in more detail hereinafter.

In order to rapidly defrost low temperature evaporator I3a, the refrigerant vapor is by-passe d around the condenser and conveyed directly from the rectifier to the low temperature evaporator. For this purpose, a conduit 12 is connected at one end to conduit 56 and at its opposite end to conduit 34 leading to the inlet end of evaporator section I 3a. Conduit I2 is formed with a U-shaped portion to provide a liquid trap I4. In order to retard or stop the flow of weak inert gas into evaporator section I3a during a defrosting period, a by-pass is provided in the inertgas circuit. This by-pass includes a conduit 16 connected at one end to conduit 34 and at its opposite end to conduit I3c which leads from the low to the high temperature evaporator section. Conduit I8 is formed with a U-shaped portion to provide a liquid trap I8. In practice, conduits 34 and I8 and gas heat exchanger I4 are provided with suitable thermal insulation (not shown). Trap I8 is connected to trap I4 by means of a conduit 88. Liquid in trap 14 is arranged to be heated by any suitable means, such for example as an electric change relation with low temperature evaporator section I3a and connected to switch 88 by a capillary tube 92, controls the deenergization of the heating element.

Referring now to Figs. 2 and 3, the'apparatus illustrated in Fig. 1 is mounted in the cabinet 28 with the low temperature evaporator 13a located in freezing compartment I8, the high temperature evaporator I3b located in food storage compartment 22 and a generator I8 located principally in an apparatus compartment I88. The otherparts of the apparatus are located either in apparatus compartment I88 or in a vertical passage I8I at the rear of the cabinet. Gas is supplied to the burner 54 from a supply conduit I82 and control vdevice 94. It is to be noted that the generator I8 audios erator. As stated above, per se is not a part of my invention and the useoi a horizontal generator inFig. 3 is merely for convenience in illustrating the relationship of my control device to a generator. The patent to Ullstrand No. 2,252,791, granted August 19,' 1941. for example, illustrates and describes a well known type of horizontal generator, portions of which I have illustrated in Fig. 3.

The control device 94, shown in detail in Fig. 4, comprises an annular casing or housing consisting of an annular body member I03, a front cover plate I04, and a rear cover plate I05, the cover plates being secured to the body member by suitable machine screws (not of body member shown). The interior I03 is divided by a partition I03 having a central boss I01 through which is drilled a valve opening I08. Extending through the valve opening is a valve stem I09 provided at one end with a valve member H in a valve chamber III. The boss I01 is machined to form a seat for valve member I I0 so that the latter may control flow of gas through the valve opening I03. The valve member is biased to its closed position by a suitable coil spring I I2. In a valve chamber I I3 on the other side of the partition I06 there is located an expansible diaphragm II4 of an expansible fluid thermostat. Expansible diaphragm II4 is mounted on a resilient diaphragm III which is secured at its edge with a suitable gasket between body member I03 and front cover member I04, thus sealing the valve chamber II3. Expansible diaphragm H4 is connected by acapillary tube 91 to a sensitive bulb 95 located in thermal transfer relation with the high temperature evaporator I3b, as shown in Figs. 1-3.. The sensitive bulb 95, capillary tube 91 and expansible diaphragm II4 are charged with a suitable temperature sensitive fluid as well known in the art. As shown, expansible diaphragm I I4 is located in operativerelation with the valve stem I09, whereby movement of the expansible diaphragm responsive to variation in temperature of the high temperature evaporator I3b is transmitted by valve stem I09 to valve member I I0 to control the flow of fuel gas through valve passage I08. Body member M13 is provided with an external boss I I3,

drilled for passage of gas therethrough into valve chamber I I3 and tapped for a gas pipe connection to supply conduit I02. 'A second external boss i i1 is drilled for passage of gas from the other valve chamber III and is tapped for a gas pipe connection to the burner 54. Thus, the supply of gas to burner 54 is controlled by valve member I I0 which is operated by the expansible diaphragm II4 in accordance with the temperature of the high temperature evaporator I3b.

In order to provide a minimum flow of gas to burner 54 to maintain a pilot flame when valve I I0 is closed, there is provideda by-pass conduit irom valve chamber II3 comprising passages i50,

iI, I52 and I53, as best seen in Fig. 5. The by-passed flow of gas from passage I5I into passage I52 is adjusted by a screw type needle valve (Fig. 2). Burner 54 is provided with a thermostatic safety cut-out valve I55, of a type well known in the art, and with a burner lighter tube E55 controlled by a normally-closed manuallyoperated push valve I51. As shown in Fig. 5, gas is admitted to the lighter valve through a passage I58 from valve chamber II3.

As shown, the control device 94 is positioned in the apparatus compartment of the refrigerator cabinet, which position renders the control somewhat inaccessible, or at least inconvenient, to adthe refrigerating system Just. Therefore,

thermostatically-operated valve stops (not shown) may be provided for limiting I provide a remotely-operated adjustment generally similar to that illustrated and described in my U. 5. Patent No. 2,123,920, granted July 19, 1938. Referring again more particularly to Fig. 4, there is provided in the outer cover plate I34 an insert bushing I II which is internally threaded to receive an adjusting screw I I8 provided with a rounded portion I20 on its inner end and an octagonal head I2I on its outer end. The outer end of screw H9 is drilled and tapped to receive a machine screw I22. The rounded inner end of screw III forms an abutment for a member I24. Member I24 projects centrally through the resilient diaphragm H5 and is secured thereto by a retaining nut I25, thus forming a means by which the expansibie diaphragm I I4 is mounted on resilient diaphragm II! and also a means by which capillary tube 91 is connected to expansible diaphragm II4; a

passage I25 through the-element I24 serves this purpose. A grooved pulley I21 formed with an octagonal recess, is mounted on the octagonal head of adjusting screw II9'and secured thereto by machine screw I22. Rotation of the pulley moves adjusting screw II9 toward or away from member [24, thereby varying the position of member I24 to eflect an adjustment or setting of H0. Suitable inward and outward movement of adjusting screw II9.

Referring againto Figs. 2 and 3, an adjusting knob I28 provided with a fixed dial or index plate I30, is mounted on the end of a rod I3I which extends from the front of the low temperature compartment I8 through the rear wall of said compartment into the vertical passage IOI where it-is provided with a grooved pulley I32 similar to pulley I21 .on control device 94. The two pulleys are operatively connected by a flexible wire belt I33 provided with a guide casing I34. Turning the knob I29 causes rotation of rod I3I, pulley I32, and pulley I21, whereby the adjustment of the control thermostat is varied as previously described. Dial I30 is provided with suitable stops I30a and I30b which respectively prevent counterclockwise rotation of knob I28 beyond the point A and clockwise rotation beyond the point M. e

In accordance-with my invention, switch 88, previously referred to for energizing and deenergizing heating element 82, is manually operated to initiate a defrosting cycle and thermostatically operated responsive to the temperature of the low temperature evaporator I3a for stopping the defrosting cycle and resuming normal operation of the refrigeratingapparatus. As shown par ticularly in Fig. 2, switch 88 comprises a housing or supporting member I35 suitably mounted adjacent control device 94 in the apparatus compartment I00. A-cover plate I36 is mounted on housing I35, as by screws (not shown), and clamps or secures the edge of a resilient diaphragm I31 to the housing. An expansible diaphragm I38 is centrally mounted on resilient diaphragm I31 by means of a member I39 which is generally similar to member I24 of control device 84. Member I39 is provided with a passage (not shown) by which capillary tube 92 is connected to expansible diaphragm I38. The sensitive bulb 80, located in thermal transfer relation with low temperature evaporator 13a, capillary tube 92 and expansible diaphragm I38, are charged with a temperature-sensitive fluid and together form a fluid thermostat. An abutment pin I40, mounted centrally on one side of expansibl diaphragm I38, operates a switch lever I H which is pivot-' ally mounted on housing I 88. The switch lever is bifurcated at its lower end and adapted to loosely engage a knob I42 connected to an electric switch I42. Switch I42 which may be of any suitable type, is arranged in the conductor 84 for opening and closing the circuit to the electric heating element 82. A flexible push rod I40 is mounted for reciprocating movement in a bracket I44 and is provided at one end with'an abutment pin I45 adapted to contact switch lever I. The opposite end of rod I48 is positloned adjacent the outer face of pulley I2I attached to control device 94 so that a boss I formed on said pulley moves the push rod to the right when said pulley is-rotated clockwise to the position shown in Fig. 2, whereby abutment pin I45 contacts and moves lever I and switch button I42 to the right to close switch I42 and energize heating element 02. Push rod I4! is biased toward boss I46 by a suitable tension spring (not shown). Cover plate I36 is drilled and tapped to receive an adjusting screw 1. Screw I4! is adjusted at the factory and held in fixed position by a set screw I50. Adjusting screw I4? is formed with a passage to receive a shaft I 48 on a reset button I48. The arrangement is such that movement of the reset button to the left, as viewed in Fig. 2, manually resets the switch I42. By this arrangement, defrosting may be interrupted if it has been started inadvertently or at an inop por-tune time. 7

In operation, assume that the refrigerating system has been operating normally for a period of time and that frost or ice has accumulated on the low temperature evaporator Isa and should be removed; in other words, evaporator I311 should be defrosted. For rapid defrosting and automatic return to normal operation, control knob I29 is rotated counter-clockwise to the position shown in Fig. 2; that is, to the position where the pointer on the knob registers with the mark A on dial I30. Rotation of knob I29 to this position causes the pulley I21 of control device 94 to rotate clockwise to the position shown in Fig. 2, whereby the boss I46 on pulley I21 will have contacted and moved push rod M3 to the right causing the switch lever Hi to move switch button I42 to close switch I42, thereby energizing heating element 82. After the knob has been rotated to this defrosting position, it is immediately returned to the desired or former setting which causes thermostatic valve IEO to continue to supply gas to burner 54 and refrigerant vapor to continue to be generated by generator I in accordance with the demands of high temperature evaporator I3b. Turning knob I20 clockwise to the point marked M would cause the burner to remain on by-pass or pilot flame as long as the knob remains in this position for slow manual defrosting.

-Referring again more particularly to Fig. l, the energization of heating element 82 causes the liquid in trap 14 to be heated, whereby the liquid is vaporized and removed from the trap. The removal of liquid from trap I4 may be effected entirely by vaporization of the liquid or by vapor liquid lift action. It is preferred to utilize the latter method; therefore, the internal diameter of conduit I2 is made sufficiently small so that vapor bubbles cannot freely pass liquid therein, whereby the liquid is removed from trap I4 by lifting of liquid in conduit 12 by vapor lift action. As the liquid level in trap 14 lowers, liquid flows from trap I8 through conduit 80 into trap 14. In this manner, the liquid'is drained from trap 18 causing weak inert gas to by-pass the low temperature evaporator I3a and flow directly through conduit I8 into high temperature evaporator section I3b. Heating element 82 is so arranged relative to trap I4 that, if necessary, the last portion of liquid is removed from the bottom of the trap by vaporizing the liquid. When trap I4 is depleted of liquid, rectified refrigerant vapor flows from conduit 56 through conduits 72 and 34 into evaporator section I8a.

The flow of refrigerant vapor directly into evaporator section I 3a, together with the bypassing of inert gas around evaporator section I8a, greatly increases the partial pressure of refrigerant vapor in said section which causes the refrigerant vapor to condense therein and the heat of condensation rapidly melts the frost from the exterior of said section. The liquefied refrigerant accumulates in evaporator section I3a until it overflows the dams 26 at which time it flows through conduit I30 into high temperature evaporator section I3b. In the high temperature evaporator section, the liquid refrigerant vaporizes and difiuses into the inert gas flowing thereinto through by-pass conduit I6. In this manner, food storage compartment 22 continues to be reirigerated even though the low temperature evaporator is being defrosted. It is to be noted that the melting of frost from the low temperature section of the evaporator causes refrigerant vapor to be condensed therein, which liquefied refrigerant produces refrigeration in the high temperature section of the evaporator. In other words, the refrigerating effect of the frost on the low temperature section is used to produce refrigeration in the high temperature section.

The size and arrangement of conduit 34 and by-pass I6 is such that during a defrosting period sumcient inert gas is by-passed around the low temperature section of the evaporator to cause an appreciable increase in the partial pressure of refrigerant vapor in this section, resulting in condensation of refrigerant'v-apor therein, while at the same time this quantity of inert gas is not sumcient to reduce the partial pressure of refrigerant vapor in the high temperature evaporator section to the point that this latter section would become a freezing section. To insure that all the refrigerant vapor that is expelled from generator I0 during a defrosting period passes directly to the low temperature section of the evaporator, the trap 58 is provided at the in let to condenser I2. When trap I4 is open, the

' liquid head in trap 58, through which the refrigerant vapor bubbles during normal operation, prevents the vapor from dividing between the evaporator and condenser.

Referring again to Fig. 2, the expansible diaphragm I38 of switch control 88 is so designed that upon increase in temperature of the low temperature evaporator I3a to the melting point of ice, the pressure therein increases sufficiently to expand the diaphragm to the point that the abutment I40 contacts and moves switch lever IM to the left, thereby snapping switch button I42 to the left, whereby switch I42 is opened and heating element 82 (Fig. l) is deenergized. As shown, thermal bulb 90 is arranged in heat exchange relation with the low temperature evaporator at a point some distance from the outlet The heat capacity of been deenergized, 'condensation of refrigerant vapor continues in the low temperature evaporator until trap I4 cools to a temperature that liquid refrigerant collects therein and stops the flow of refrigerant vapor to the evaporator, dur; ing'which interval the remainder of the low temperature evaporator will have been defrosted. heating element 82 and of the vapor lift pump portion of conduit 12 is low so that after the heating element has been deenergized, this assembly cools rapidly, causing refrigerant vapor to be condensed therein and fill trap 14,1 In order to expedite the filling of trap I4, conduit 12 may be cooled in any suitable manner, as by heat transfer fins (not shown). As refrigerant vapor condenses and fills traps 1|, liquefied refrigerant flows therefrom through conduit 80 into trap 18, thereby closing by-pass l6 and causing all of the weak inert gas to flow through conduit 34 into the low temperature evaporator. Liquid refrigerant having been accumulated in the low temperature evaporator section during the defrosting period, refrigeration is resumed in this section immediately upon the closing of trap It in by-pass 16.

While I have illustrated and described but one specific embodiment of my invention, it obviously may take other forms and be variously applied within the scope of the following claims.

What is claimed is:

1. A refrigerating apparatus provided with a low temperature evaporator, a high temperature evaporator and means for supplying liquid refrigerant to said evaporators, a first control mechanism for controlling the supply of refrigerant to said evaporators responsive to the temperature of said high temperature evaporator, a second control mechanism for stopping the flow of liquid refrigerant to said low temperature evaporator and for flowing refrigerant vapor thereto while continuing the flow of liquid refrigerant to said high temperature evaporator, a common control knob for adjusting said first control mechanism and for energizing said second control mechanism, and a third control mechanism thermostatically operated responsive to a predetermined high temperature of said low temperature evaporator for deenergizing said second control mechanism.

2. An absorption refrigerating apparatus including a generator, a low temperature evaporator and a high temperature evaporator, a valve for controlling a supply of heat to said generator, a thermostat for actuating said valve to normally maintain the temperature of said high temperature evaporator substantially constant, a defrosting device for said low temperature evaporator, mechanism for manually energizing said defrosting device, means thermostatically operated responsive to the temperature of said low temperature evaporator for deenergizing said defrosting device, and a common actuating mechanism for adjusting the setting of the thermostat that actuates said valve and for manually energizing said defrosting device.

3. A unipressure absorption refrigerating system including a generator, a condenser, an evaporator, an absorber, conduits, including a defrosting device, interconnecting said elements and a control mechanism, said control mechanism including a thermostatically-operated valve for controlling a supply of heat to said generator, a switch for controlling a supply of heat to said defrosting device, said switch being arranged to be closed manually andopened automatically responsive to the temperature of said evaporator, and a. common actuating member for adjusting said thermostatically-operated valve and for manually closing said switch.

4. A dual regulating and defrosting control for a unipressure absorption refrigerating system having a generator. a condenser, an evaporator, an absorber, conduits, including a defrosting device, interconnecting said elements to form a refrigerant circuit, an absorbent circuit and an inert gas circuit, said defrosting device including means for by-passing said condenser and flowing refrigerant vapor directly into said evaporator and for retarding flow of inert gas to said evaporator, said dual control including a thermostatically-operated mechanism for controlling a supply of heat to said generator, an element manually operated for energizing said defrosting device, and automatically operated for deenergizing said defrosting device, and a common adjusting member for adjusting said thermostatically-operated mechanism and for energizing said defrosting device.

5. A dual regulating and defrosting control for a unipressure absorption refrigerating system having a generator, a condenser, an evaporator, an absorber and conduits interconnecting said elements to form a refrigerant circuit, an absorbent circuit, an inert gas circuit, and a plurality of defrosting circuits, said defrosting circuits including means for-by-passing said condenser and flowing refrigerant vapor directly into said evaporator and for by-passing inert gas around said evaporator, said dual control including a thermostatically-operated valve for supplying heat to said generator in accordance with the'temperature of said evaporator, an element manually energized ior'opening said defrosting circuits and automatically deenergized responsive to the temperature of said evaporator for closing said defrosting circuits, and a common remotely-operated adjustment for adjusting said thermostatically-operated valve and for manually energizing said element.

6. An absorption refrigerating system of the unipressure type including a generator, a rectifier, a condenser, an evaporator, an absorber and conduits connecting said elements to form a refrigerant circuit and an inert pressure-equalizing gas circuit, means for by-passing said condenser and for conveying refrigerant vapor from said rectifier into said evaporator, means in said inert pressureequalizing gas circuit for by-passing at least a part of said evaporator, liquid traps in each of said by-pass means for rendering said means ineffective, a gas burner for heating said generator, a thermostatic control operated responsive to the temperature of said evaporator for supplying gas to said burner, means including a heating element for removing liquid from said traps, a switch manually operated for energizing said heating element and thermostatically operated for deenergizing said heating element, and a single adjusting element for adjusting said thermostatic control and for operating said switch.

7. An absorption refrigerating system of the unipressure type including a generator, a rectifier, a condenser, a low temperature evaporator, a high temperature evaporator, an absorber and conduits connecting said elements to form a refrigerant circuitand an inert pressure-equalizing gas circuit, means for by-passing said condenser and for conveying refrigerant vapor from said rectifier into said low temperature evaporator, means in said inert pressure-equalizing gas circuit for by- 11 passing said low temperature evaporator and for conveying inert pressure-equalizing gas directly into said high temperature evaporator, liquid traps in each of said by-pass means for rendering said means ineffective, a gas burner for heating said generator, a thermostatic control operated responsive to the temperature of said high temperature evaporator for supplying gas to said burner, means including a heating element for removing liquid from said traps, a switch which is manually closed for energizing said heating element and thermostatically opened responsive to the temperature of said low temperature evaporator for deenergizing said heating element, and a single adjusting element for adjusting said thermostatic control and for closing said switch.

8. In an absorption refrigerating system of the unipressure type, a generator, a condenser, an evaporator, an absorber, conduits interconnecting said elements to form a refrigerant circuit, additional conduits interconnecting said evaporator and said absorber to form an inert pressure-equalizing gas circuit, a defrosting device for said evaporator including a by-pass in said refrigerant cirsuit for conveying refrigerant vapor directly into said evaporator, a liquid trap in said by-pass, a second by-pass in said inert pressure-equalizing gas circuit for retarding the flow of inert pressureequalizing gas to said evaporator, a liquid trap in said second by-pass and means interconnecting said by-passes for flow of liquid therebetween, means for heating said generator, a thermostatically-controlled valve operated responsive to the temperature of said evaporator for controlling the supplyof heat to said generator, means for re-' moving the liquid from said traps to render the traps ineffective and thereby initiate a defrosting cycle, said last-named means being manually started and automatically stopped responsive to the temperature of said evaporator, and a common control element for remotely adjusting said thermos'tatically-controlled valve and for inanually initiating a defrosting cycle.

9. In an absorption refrigerating system of the unipressure type, a generator, a condenser, a low temperature evaporator, a high temperature evaporator, an absorber, conduits interconnecting said elements to form a refrigerant circuit, additional conduits interconnecting said evaporators and said absorber to form an inert pressureequalizing gas circuit, a defrosting device for said low temperature evaporator including a bypass in said refrigerant circuit for conveying refrigerant vapor directly into said low temperature evaporator, a liquid trap in said by-pass, a second by-pass in said inert pressure-equalizing gas circuit for retarding the flow of inert pressure-equalizing gas to said low temperature evaporator, a liquid trap in said second by-pass, means interconnecting said by-passes for flow ofliquid therebetween, means for heating said generator, a thermostatically-controlled valve operated responsive to the temperature of said high temperature evaporator for controlling the supply of heat to said generator, means for removing the liquid from said traps to render the traps ineffective, said last-named means being manually started and automatically stopped responsive to the temperature of said low temperature evaporator, and a common control element for remotely adjusting said thermostatically-com trolled valve and for manually initiating a defrosting cycle.

10. In a refrigerating system of the unipressure type, a generator, a condenser, a low tempera- 12 ture evaporator, a high temperature evaporator, an absorber, conduits interconnecting said elements to form a refrigerant circuit, additional conduits interconnecting said evaporators and said absorber to form an inert pressure-equalizing gas circuit, a defrosting device including a conduit connecting said generatorand the low temperature evaporator for flow of refrigerant vapor therethrough, a liquid trap in said lastmentioned conduit for blocking flow of refrigerant vapor therethrough, a conduit in said inert pressure-equalizing gas circuit for by-passing the low temperature evaporator and-for conveying inert pressure-equalizing gas directly into the high temperature evaporator, a liquid trap in said last-mentioned conduit for blocking flow of inert pressure-equalizing gas therethrough, a dual regulating and defrosting control, said dual control including a thermostatically-operated valve for controlling a supply of heat to said generator responsive to the temperature of said high temperature evaporator, a mechanism that is manually operated to initiate a defrosting cycle and thermostatically operated responsive to the temperature of the low temperature evaporator for interrupting said defrosting cycle, and a common control knob for adjusting said thermostaticallyoperated valve and for operating said mechanism to initiate a defrosting cycle.

11. In a refrigerator, a cabinet having a freez-= ing compartment, a food storage compartment and an apparatus compartment, an absorption refrigerating apparatus including a low temperature evaporator in said freezing compartment. a high temperature evaporator in said food storage compartment'connected to the low temperature evaporator 4 for flow of refrigerant fluid from the low to the high temperature evaporator and a generator and control mechanism in said apparatus compartment, a defrosting device including means for increasing the vapor pressure of refrigerant vapor in the low temperature evaporator, for decreasing the vapor pressure of refrigerant vapor in the-high temperature evaporator and for conveying refrigerant vapor into the low temperature evaporator which vapor is condensed therein and liquid refrigerant produced thereby flows into the high temperature evaporator to produce refrigeration therein, said control mechanism including a thermostaticallyoperated valve for supplying heat to said generator, a switch manually operated for energizing said defrosting device and thermostatically operated responsive to the temperature of said low temperature evaporator for deenergizing said defrosting device, and a common adjusting knob accessibly located in an upper part of said cabinet for adjusting the setting of said thermostatically-controlled valve and for energizing said defrosting device.

12. In a refrigerator, a cabinet having a freezing compartment, a food storage compartment and an apparatus compartment, an absorption refrigerating apparatus including a low temperature evaporator in said freezing compartment, a high temperature evaporator in said food storage compartment and a generator and control mechanism in said apparatus compartment, a defrosting device including means for conveying refrigerant vapor to said low temperature evaporator, means for increasing the vapor pressure veyed thereto is condensed therein and the latent heat of condensation is utilized to heat said low 13 temperature evaporator, means for conveying liquid refrigerant from the low temperature evaporator to the high temperature evaporator whereby refrigeration is produced by the high temperature evaporator during the defrosting of the low a condenser, an evaporator, an absorber and con-- duits, including a defrosting device, interconnectin said elements, said control including a thermostatically-operated valve for controlling a supply of heat to said generator, a mechanism for controlling a supply of heat to said defrosting device, said mechanism being arranged to be manually energized and automatically deenergized responsive to the temperature of said evaporator, a common actuating member for adjusting said thermostatically-operated valve and for manually energizing said mechanism, and a manually-operated device for deenergizing said mechanism.

14. In a refrigerating system of the unipres sure type, a generator, a condenser, a low temperature evaporator, a high temperature evaporator, an absorber, conduits interconnecting said elements to form a refrigerant circuit, additional conduits interconnecting said evaporators and said absorber to form an inert pressure-equalizing gas circuit, a defrosting device including a conduit connecting said generator and the low temperature evaporator for flow of refrigerant vapor therethrough, a liquid trap in said last-mentioned conduit for blocking flow of a refrigerant vapor v 14 interrupting said defrosting cycle, a common control knob for adjusting said-thermostatically-operated valve and for operating said mechanism to initiate a defrosting cycle, and a reset mechanism for manually interrupting a defrosting cycle.

15. In a refrigerator, a cabinet havin a freezing compartment, a food storage compartment and an apparatus compartment, an absorption refrigerating apparatus including a low temperature evaporator in said freezing compartment, 9.

high temperature evaporator in said food storage compartment and a generator and control mechanism in said apparatus compartment, a defrosting device including means for conveying refrigerant vapor into said low temperature evaporator wherein said vapor is condensed and the latent heat of condensation is utilized to heat said low temperature evaporator, and means for conveying liquid refrigerant from the low temperature evaporator to the high temperature evaporator whereby refrigeration is produced in said high temperature evaporator during the defrosting of said low temperature evaporator, said control mechanism including a thermostaticallyoperated valve for supplying heat to said generator, a switch manually operated for energizing said defrosting device and thermostatically operated responsive to the temperature of said low temperature evaporator for deenergizing said defrosting device, a common adjusting knob accessibly located in an upper part of said cabinet for adjusting thesetting of said thermostaticallycontrolled valve and for energizing said defrosting device, and a reset mechanism for manually,

deenergizing said defrosting device.

16. Refrigeration apparatus including a cooling element, automatic control means comprising a first thermostat operative to maintain the temperature of said cooling element within a subtherethrough, a conduit in said inert pressureequalizing as circuit for by-passing the low temperature evaporator and for conveying inert pressure-equalizing gas directly into the high tem-' -controlling a supply of heat to said generator responsive to the temperature of said high temually operated to initiate a defrosting cycle and thermostatically operated responsive to the temperature of the low temperature evaporator for perature evaporaton'a mechanism that is manstantially constant value or range, means operative to cause the temperature of said cooling means,"automatic means comprising a second thermostat for stopping said modifying means upon a predetermined rise in a temperature condition affected by said cooling element, and manual means for stopping said modifying means independently of the operative condition of said automatic means.

SVEN W. E. ANDERSSON.

REFERENCES CITED The following references are of record in the file of this patent:

' rmrrnn sra'rns PATENTS Name Date Dick May 14,1985 2,109,607 Andersson' Mar. 1, 1948 Number

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