US2307168A - Refrigeration - Google Patents

Description

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D. G. SMELLIE 37mm 5, MM

REFRIGERATION Filed Feb. 5, 1940 INVENTOR @mmd M www@ ATTORNEY imateuted en. 5, i943 Zwm untrue. autres eur-eur uretra REIFRMGERATION Donald G. Smellie, Danton, Ohio, assigner to rlhe Hoover Company, North Canton, Ohio v Application February 5, 1940, Serial No. 317,37'l

(Ci. 62-1l9.5)

18 Claims.

in which a circulating motor is hermetically sealed within the system in order to circulate the duids therein. Motors of this type must be lubricated. However, considerable difficulty may arise in handling and installing the system due to the iact that under such circumstances the lubricant in the motor shell may be displaced by foreign material such as absorption solution and once displaced it will be very diicult to return-the lubricant to its normal environment without mafactor, however, is not disadvantageous by reason Y of the fact that there is an appreciable lapse of 2 time between energization of the boiler heater and discharge of Aliquid refrigerant into the evaporator and circulation of inert gas and absorption solution during this period of time is not desirable. Therefore, the delay in action -of the motor with respect to the actuation of the refrigeration control mechanism and energization of the boiler heater may advantageously be utilized to improve the operating characteristics of the system.

With some lubricants, such as those having a high paramn content, the period required to liquefy the same by the heat generated by the very small current flowing through the windings of motors is excessive, wherefore it is an object of the present invention to provide an additional heating element so designed and arranged that the motor will come into operation substantially simultaneously with supply oi liquid refrigerant to the evaporator and will be de`energized Biltomatically after liqueflcation or softening of the lubricating material in which the motor issubmerged. l

It is a further object of the invention to provide an apparatus of the above character in which the geal or become non-duid at ordinary temperatures and which includes a heating apparatus constructed and arranged to maintain the lubricant in the liquid orfluid state substantially continuously after initial installation of the apparatus. It is a still further object of the present invention to provide an absorption refrigerating system which includes a lubricated circulator provided with a lubricant heater for softening the lubricant, which heater is rie-energized in response to a temperature change in a particular portion of the refrigeratingsystem.

Other objects and advantages of the invention will become apparent as the description proceeds when taken in connection with the accompanying drawing, in which:

Figure 1 is a diagrammatic representation of a three-ud absorption refrigerating system embodying the present invention;

Figure 2 is a partial sectional elevational view drawn on an enlarged scale of the motor circulator unit of the system; l

Figure 3 is a schematic wiring diagram of a modified form of control circuit.

Referring now to the drawing in detail and first to Figure 1 thereof, there is illustrated a threefluid absorption refrigerating system comprising a boiler B, an analyzer D, an air-cooled rectifier R, a tubular air-cooled condenser C, an evaporator E. a gas heat exchanger G, a tubular iny clined air-cooled absorber A, a liquid heat exchanger L, a solution reservoir S, and a circulating fan F which is driven by an electrical motor M. These elements are suitably connected by various conduits to form a plurality of gas and liquid circuits constituting a complete refrigerating system burner H which will be described in more detail' hereinafter. The application of heat to the boiler B generates refrigerant vapor from the solution therein contained. The vapors so generated pass upwardly through the analyzer D in counteriiow to the strong solution owingdownwai-diy therethrough. After traversing the analyzer D the vapor is conveyedfrom the upper pormotor is immersed in a lubricant which will con- Ition thereof to the upper portion of the condenser C by means of a conduit II which includes the rectifier R.

The lean solution formed in the boiler by the generation of refrigerant vapor therefrom is conveyed from the boiler to the solution reservoir S by way of the conduit I2, the liquid heat exchanger L, and a finned looped conduit I3 which also serves as a solution precooler.

The solution reservoir S is vented by means of a conduit I4 which connects to the suction conduit I5 of the circulating fan F. The conduit I5 extends between the suction side of the fan F and the upper portion of the absorber A.

The lean solution is conveyed from the reservoir S to the conduit I5 adjacent its point of connection with the absorber A by means of a gas lift pumping conduit I6. Pumping gas is supplied to the conduit I6 by means of a conduit II which is connected between the discharge conduit I8 of the circulating fan F and the gas lift pump I 6 below the liquid level normally prevailing therein and in the solution reservoir S.

The lean solution ows downwardly through the absorber A in counterflow relationship to a rich mixture of inert gas and refrigerant vapor which is supplied to the bottom portion of the absorber from the evaporator in a manner to be described hereinafter.

In its traverse through the absorber the lean solution absorbs refrigerant vapor from the gas mixture flowing therethrough and the resulting heat of absorption is rejected by the cooling ns to cooling air flowing over the exterior Walls of the absorber vessel. 1

The strong solution thus formed in the absorber is conveyed therefrom to the upper portion of the analyzer D by way of the'conduit I9, the-liquid heat exchanger L, and a conduit 2l), thus completing the absorption solution circuit.

Lean inert gas is formed in the absorber A by the absorption of refrigerant vapor and is then conveyed from the upper portion of the absorber to the suction side of the circulating fan F by means of the conduit I5. The inert gas is placed under pressure in the fan F and is then conveyed therefrom to the lower portion of the evaporator E by Way of the conduit I8, the outer path of the gas heat exchanger G and an evaporator gas supply conduit 22.

The refrigerant vapor which is supplied to the condenser C is liquefied therein by heat exchange relationship vwith atmospheric air and is then conveyed therefrom to the bottom portion of the evaporator E by way of the conduit 23 and a conduit 24 which includes a downwardly extending U-shaped looped portion which is designed to carry a liquid seal and a pressure balancing column of the liquid refrigerant. The conduits 23' and 24 are vented by means of a conduit 25 to the rich gas side of the gas heat exchanger G. As a result of this construction the pressure prevailing in the condenser and the condenser side of the conduit 24 is` that prevailing on the discharge side of the evaporator whereas the pressure prevailing on the discharge side of the conduit 24 is that prevailing .at the inlet to the evaporator. This pressure difference is compensated by a pressure balancing liquid column which is supported in the condenser side of the conduit 24.

The evaporator E may be of any desired type of construction. However, as diagrammatically illustrated herein, it is of the type in which the high velocity gas stream iiowing through the evaporator serves to sweep or drag liquid refrig- CII erant upwardly therethrough as it is evaporating to produce refrigeration. A preferred construction of this type evaporator is disclosed and claimed in the co-pending application of Curtis C. Coons and William H. Kitto, Serial No. 220,189, filed July 20th, 1938. An anti-blocking and over- ;tiow drain 27 is connected between the upper portion of the bottom conduit in the evaporator E and the strong solution return conduit I9.

The liquid refrigerant supplied to the bottom portion of the evaporator E meets a high velocity gas stream flowing upwardly therethrough with the result that the liquid refrigerant is propelled upwardly through the evaporator as it is evaporating into the gas stream to produce useful refrigeration.

The top portion of the evaporator is provided with a large diameter finned box-cooling conduit 28 into which both the liquid and gas discharge. The gas ows ata slow rate through this conduit, hence the same is inclined rearwardly in order to permit liquid to flow by gravity. The resulting rich gas and unevaporated material in the evaporator is conveyed from the conduit 28 into the rich gas side of the gas heat exchanger G by means of a conduit 29. After traversing the rich gas side of the gas heat exchanger the rich gas and unevaporated material is drained therefrom into the bottom portion oi' the absorber A by means of the conduit 30. Thus, the conduit 30 serves as a rich gas return conduit and as an evaporator drain. The rich gas then flows upwardly through the absorber A in counterfiw relationship with the lean solution flowing downwardly therethrough in the manner heretofore described.

It will be noted that with the construction thus provided evaporator drainage is conveyed to the conduit' I9 in a manner such that it cannot reach the circulating fan and the fan is so connected to the absorber that lean solution cannot be conveyed thereinto from the lean solution supply lines. This is of considerable importance in pre venting absorbing solution from nding its way to the motor shell, as will be explained in more detail hereinafter.

Referring now to Figures 1 and 2, it is apparent that the fan casing F carries a sealed motor shell 35 depending therefrom. The motor M consists of a rotating element 36 which is mounted within the shell and a stationary field winding or stator structure 3I-which is mounted on the outside of the shell whereby the magnetic circuit for the induction rotor 36 must pass through the shell 35. The rotorA is supported on suitable bearing assemblies indicated generally at 38 and 39 with-v in the shell 35. The motor shaft 40 passes through the bearings 38 and carries a suitable fan within the fan housing 4I in a conventional manner.

The depending motor shell 35 is lled with a suitable lubricant up to the level of the line indicated generally at 44; that is, the rotor is completely submerged and part of the bearing 38 is submerged in the lubricant.

One such lubricant is parafiin and it is obtainable in a long range of melting' points and specic gravity. By selecting paraiiin of the proper melting point or by mixing it with other lubricants, almost any melting point desired can be obtained. This lubricant has'the characteristic that it is non-fluid at ordinary room temperatures but will become uld when heated above that temperature in order to llubricate the beart to permit the motor to rotate. In its nonhuid state the drag of this lubricant is sumcient to stall the rotor of the motor.

In this connection it should be emphasized that this motor is very small and develops vonly sufncient power to circulate the inert gas with a few inches of water pressure differential, hence the lubricant drag is easily sumcient to stall the se. l

In order to shorten the time required for the lubricant to be rendered fluid by heat, a. suitable electrical heating element t is positioned about the motor shell d5 and at the lower end thereof below the stator 3l of the electrical motor. The heater is encased in a suitable refractory channel-shaped element tt which protects the stator windings from the heat. A housing M of insulating material is suitably attached to the mttom portion of the motor shell beneath the heater t5 and is provided with a switching eri-'- i closure or chamber it. An electrical switch indicated generally at t9 is encased within the chamber it. A bracket is attached to the bottom portion of the shell 35 and carries'a thermostatic strip or disc 5I, as may be desired,

directly above the switch t9.v The disc 5I is provided with an actuating button 52 which may be made of a composition insulating material and is positioned to strike the movable element 53 o the switch da to actuate thesame. l

As was mentioned previously a heater H is provided for the'boiler B. Gas is supplied to the heater H from a suitable source of supply through a conduit 5t which includes a solenoid valve V. d small by-pass 56 is provided around the valve V in order to maintain a small ignition llame on the heater H. Also included in the conduit adjacent the burner is a, suitable thermostatic safety cut-o device 5l which is arranged to discontinue supply of fuel to the burner completely upon failure of dame thereupon, as for example in case the small igniting or pilot flame is extinguished by a draft or the like.

The apparatus is controlled by means of a suitable thermostatic switching mechanism indicated generally at at and provided with a capillary conduit ti which connects to a duid containing bulb tt positioned to be influenced by temperature changes at or adjacent the evaporator E. The exact construction of the thermostatic switching mechanism lill is conventional and need not be disclosed in detail herein. Power is supplied to the apparatus from a pair of electrical conductors tt and tt. 'I'he conductor 63 connects directly4 to the switching mechanism Gil. an electrical conductor t5 is connected to the switching mechanism t@ and to the windings 66 of the stator 3l o f the motor M. The other side of the winding 6d connects directly to the elec* trical conductor tt. The heating element d5 is connected to the conductor 65 by means of a conductor hl. The other side of the heating element dit is connected to the switch ftd by means of a conductor th and the switch t9 then connects to the conductor tt by means of a conductor 69. IThe Vsolenoid valve V is connected to the conductors td and tt by means of the conductors ll l and lt, respectively.

The operation of the device, except insofar as the same has already been disclosed in connection with the construction of the refrigeratlng apparatus per se, is as follows: Assuming a demand for refrigeration, the thermostatic switch tt will complete the electrical circuit between the conductors tt and t5. This will then directly energize the windings Bt of the motor and the solenoid valve V. Upon energization of these elements the ame will be turned up upon the burner H for the purpose of heating the boiler and if the motor M has cooled sulciently to cause congelation of the lubricant contained in the shell 35, the thermostat 5I will have flexed. upwardly tothe position shown in Figure 2 to permit the movable element 53 of the switch t9 to move to closed circuit position, thereby energizing the heater t5. After a lapse of a short period of time the heat of the current flowing in the winding 66 and the heat of the heating element l5 will be suiiicient to render the lubricant fluid and thereby to eliminate the braking action thereof -upon the motor.- The motor now comes into operation to circulate the inert gas and absorption solution through their responsive circuits. The period required to heat the lubricant sufficiently to render the same fluid is such that the motor will come into operation at `sub stantially the time liquid refrigerant begins to discharge through the conduit 2d into the evaporator E. I

Immediately the motor lubricant becomes iiuid the temperature thereof is at a value suflicient to actuate the thermostat 5l which causes the same to flex downwardly, as viewed in Figure 2, to shift the movable element 53 of the switch t9 to open circuit position thereby dee-energizing the heater t5. The heat supplied from the motor itself is suilcient to maintain the lubricant in a fluid state once the same has been initially conditioned by the heating element d5. Hence, a differential heating rate is applied to the lubricant. a high rate for melting and a low rate to maintain the lubricant in a uid state.

The apparatus remains in this condition so long as the temperature of the evaporator has all not been lowered to the value for which the control mechanism is set. Once the evaporator temperature lowers to the value for which the control has been set, theclrcuit between the conductors 63 and 651s broken by the switching mechanism 6d, the valve V closes thereby leaving only the small pilot or ignition ame upon the burner H which is maintained by gas flowing through the conduit 56`and the circulating motor is de-energized. `If the motor remains de-energized for an appreciable period of' time, and it usually will remain de-energized for such a period of time, the motor will cool sufiiciently to cause congelation of the lubricant within the shell it and the thermostat 5| will exupwardly tothe position shownfin Figure 2, to close the circuit between the conductors 6B and 69, thereby conditioning the heater t5 to be energized upon closure of the circuit between the conductors t3 and 65 by the control mechanism 60.

As at present advised the illustrated construction is the preferred arrangement, however, the thermostatic cut-out for the lubricant heater may be arranged to de-energize the heater in response to a change in the condition of another portion of the system induced by energization of the system. For example, the thermostatic cutout for the lubricant heater could be arranged to respond to the temperature of some portion of the pipe il.

This pipe is heated by hot vapor enroute to the condenser. There is a time lag between initiation of full ame operation of the The present invention provides a very advantageous arrangement in that loss of lubricant from the motor shell and/or displacement thereof by liquid refrigerant orabsorption solutionI during transit of the refrigerating system and installation thereof is absolutely prevented by reason of the fact that the lubricant is in a nonfluid state prior to operation thereof. 'Ihis is of considerable importance as it is impossible to insure that the apparatus will be maintained in upright position during handling andshipment.

The lubricant also has an advantageous effect with respect to the operation of the refrigerating system andP control thereof in that the arrangement herein provided automatically prevents circulation of absorption solution and inert gas until the boiler has been fully heated and liquid refrigerant has been supplied to the evaporator at which time the system is conditioned to go into complete operation. Considerable loss is entailed if the inert gas is circulated during the period of time required to bring the liquid in the boiler up to the boiling temperature because this circulates absorption solution thereby continuously removing the heated liquid from the boiler and cooling the same in the absorber and it also circulates inert gas warmed by contact with the solution in the absorber through the evaporator thus adding to the net refrigerating load when liquid refrigerant is eventually supplied to the evaporator. 'I'he present arrangement obviates these diculties.

In Figure 3 there is diagrammatically illustrated a modied form of the invention. This form of the invention is designed and intended to be utilized with a refrigerating system identical with that illustrated and described in connection with Figures 1 and 2, the only differences being in the arrangement of the wiring. Therefore, only a schematic wiring diagram has been illustrated. Certain portions of the apparatus illustrated in Figure 3 are identical with portions illustrated and described in connection with Figures 1 and 2 and are therefore given the same reference characters primed.

In the form of the invention illustrated in Figure 3, electrical energy is supplied to the apparatus by the conductors 30 and 8|. ductor 8|] connects directly to one side of the winding 66 of the circulating motor and it is connected to the valve V and heater i6 by the conductors 82 and 83, respectively. The opposite sides of the winding 66' is connected to the valve V by the conductor 84 which in turn is connected to the control 60' by a conductor lib. The heater i6 is also connected to the thermostatic switch i9 by means of a conductor 36. The switch t9' is then connected to the control lill and to the supply line 8| by means of a conductor B1. v

As may readily be seen from an inspection of Figure 3, in this form of the invention the Windings 56 and the valve V' are directly under the control of the thermostatic switching mechanism 60' but the heater Mi and associated thermostatic switch is connected in parallel in -such fashion that the'same does not come Within the control of the control mechanism B', wherefore the heater i6' will be energized whenever the temperature of the lubricant within the motor housing drops below a predetermined point, provided electrical energy is supplied, in order to maintain the lubricant in a fluid condition and will be de-energized by the thermostat whenever the temperature of the vlubricant is above The con- "ill aaovgi its non-duid point in order that the motor may be in condition for starting operation at any time.

This form of the invention does not delay the action of the motor with respect to the action oi the boiler in the manner characteristic to the form of the invention described in connection with Figures 1 and 2. In this form of the invention it is intended that the by-pass conduit bb' will .be constructed to maintain suiiicient llame on the heater H to keep the boiler B' at substantially the vaporization point at all times so that vapor will be evolved substantially immediately `the valve V' is opened by the control mechanism This form of the invention is particularly applicable for use in refrigerating units which are called upon to meet sudden heavy demands and also for units which are designed to be used in unusually cold climates where the delay caused by continual softening or melting of the lubricant would beobjectionable and also the cooling of the boiler in the off-cycle period with a mere pilot ame on the burner H would be objectionable.

In accordance with the invention herein disclosed there is provided an absorption refrigerating apparatus in which the motor is immersed in a solid lubricant which is rendered fluid after installation of the apparatus and is either maintained continuously in a iiuid condition thereafter or is periodically reheated to render the lubricant fluid whenever the apparatus is called upon to produce refrigeration.

Though the invention has been illustrated and described herein in considerable detail, various alterations and changes may be made in the proportion, construction and arrangement of parts without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. Absorption refrigerating apparatus of th type having a hermetically sealed uid circulator therein, an electrically driven element for said fluid circulator also sealed within the apparatus, a lubricant for said electrically driven element sealed in said apparatus, said lubricant being of the type which is non-fluid at atmospheric temperatures, an electrical heater for said lubricant, and means for opening the energizing circuit of said electrical heater when the temperature of said lubricant is suiiciently high to maintain the same in the fluid state.

2. Absorptiond refrgerating apparatus comprising an inert gas circuit including an evaporator and an absorber, a solution circuit including a boiler and said absorber, means for liquefying refrigerant vapor produced in said boiler and for supplying the liquid to said evaporator, a circulating device included in said inert gas circult, a gas lift circulator in said solution circuit, means for conveying pumping gas from said inert gas circuit to said gas lift circulator, a motor for driving said circulating device having its rotating element sealed within the inert gas cirlubricant,

asoma cuit, a lubricant submerging said rotating element, said lubricant being of the type which congeals at atmospheric temperatures, a heater for said lubricant, and means for de-energizing said heater when the temperature of said lubricant rises sumciently to liquefy the same.

3. Absorption refrigerating apparatus comprising an inert gas circuit including an evaporator and an absorber, a solution circuit including a boiler and said absorber, means for liqueiying refrigerant vapor produced in said boiler and for supplying theliquid to said evaporator, a circulating device included in said inert gas circuit, a gas lift circulator in said solution circuit, means ior conveying pumping gas from said inert gas circuit to said gas lift circulator, a motor for driving said circulating device having its rotating element sealed within the inert gas circuit, a lubricant at least partially submerging said rotating element, said lubricant being of the type which congeals at atmospheric temperatures, a heater for said boiler, a heater for said refrigeration demand responsive means arranged `to energize said heaters and said motor in response to refrigeration demand, and means for de-energizing said lubricant heater independently of said refrigeration demand responsive means when the temperature of the lubricant has risen suciently to liquefy the same.

i. In an absorption reirigerating system ci the three-iiuid type, a motor driven ciroulator for circulating iiuids in the system, said motor including a rotating part sealed within the system and at least partially immersed in a lubricant, a heating element for said lubricant and means responsive to the temperature oi' said lubricant for controlling the operation of said heating element.

5. Absorption refrigerating apparatus including a part in which vapor is expelled irom solution, a part in which such vapor is liquefied, a part in which the liquid is vaporized in the presence of an inert gas to produce a cooling edect, a part in which the vapor is absorbed from the inert gas, a power driven circulator connected to circulate uids in the apparatus, said power driven (means including a rotary drive member having its lower portion submerged in a' lubricant, means ior heating said part in which vapor is expelled, refrigeration demand responsive means for controlling the operation of said heating means and of said power driven means, means for controlling the viscosity of said lubricant, and means responsive to a condition of said lubricant which is a measure of the viscosity thereof for regulating said viscosity controlling means.

6. Absorption refrigerating apparatus. including a part in which vapor is expelled from solution, a part in which such vapor is lidueiied,l a part in which the liquid is vaporized in the presence of an inert gas to produce a cooling edect, a part in which the vapor is absorbed from the inert gas, a power driven circulator connected to circulate fluids in the apparatus, said power driven means including a rotary drive member at ieast'- in part submerged in a lubricant, means for heating said part in which vapor is expelled, refrigeration demand responsive means for controlling the operation of said heating means and of said power driven means, means for controlling the viscosity oi said lubricant, and means responsive to a condition of said lubricant which is a measure oi the viscosity thereof for regulating said viscosity controlling means, said refrigeration demand responsive means being operative to render said viscosity responsive means operative or inoperative in accordance with refrigeration demand.

7. Sealed absorption refrigerating apparatus of the three-fluid type including an evaporator and an absorber connected for the circulation of inert gas therebetween, means for supplying reirigerant in liquid phase to the evaporator, a

fan for circulating the inert gas between the evaporator and the absorber, a motor having a rotating element for driving said fan sealed within the apparatus and supported in a lubricant which serves to protect the said rotating element from contact with the active fluids within the apparatus, said lubricant being non-fluid at atmospheric temperatures whereby it is not displaced in handling of the apparatus, means for energizing said motor in response to refrigeration demand, means for rendering said lubricant iluid, and means for governing said means for rendering said lubricant fluid.

8. Sealed absorption reirigerating apparatus of the three-iiuid type including an evaporator and an absorber connected for the circulation of inert gas therebetween, means for supplying refrigerant in liquid phase to the evaporator, a fan for circulating the inert gas between the evaporator and the absorber, a motor having a rotating -element for driving said fan sealed within the apparatus, said rotating element being housed Within a thin Walled shell depending from said fan and sealed from the surrounding media, a iield winding for said motor embracing the outside part of said shell, said shell being iilled to a level sumcient to submerge said rotating element with a lubricant which is sufiiciently thick at atmospheric temperatures to i0 stall said motor, a, heater for said lubricant also embracing said shell, means for energizing said refrigerant liquid supply means, said motor, and said heater, and means for de-energizing said heater only after energization thereof when said heater has rendered the lubricant fluid enough to the three-iluid type including an evaporator and r an absorber connected for the circulation of 5u inert gas therebetween, means for supplying reirigerant in liquid phase to the evaporator, a fan for circulating the inert gas between the evaporator and the` absorber, a motor having a rotating element for driving said fan sealed Within the du within a thin Walled shell depending from said fan and sealed from the. surrounding media, a eld winding for said motor embracing the outside part of said shell, said shell being filled to a level sumcient to submerge said rotating element with a lubricant which is sufficiently thick at atmospheric temperatures to stall said motor, an electrical heater for said motor also embracing said shell, means for shielding said iield windingr from the eiect of said heater, means for energizing said refrigerant liquid supply means, said motor and said electrical heater in response to refrigeration demand, a thermostatic switch connected to control said electrical heater and arranged to be responsive to the temperature of said lubricant for de-energizing said heater when said lubricant has been heated sufficiently to'al- 10W said fmotor to start, said heater being arid ranged to heat said lubricant suiciently to alapparatus, said rotating element being housed loW said motor to start substantially at the time liquid refrigerant is supplied to said evaporator.

10. Absorption refrigerating apparatus including a generator for expelling refrigerant vapor from solution, an evaporator, means for liquefying refrigerant vapor produced in said generator and for supplying the liquid to said evaporator, an absorber connected with said evaporator for --circulation of inert gas therebetween, a power driven circulator arranged to propel inert gas through said evaporator and said absorber, a motor for driving said circulator including a rotary part sealed within said apparatus, said rotating part being supported in a lubricant which is non-iluid at atmospheric temperatures, a heater for said lubricant, control means for said heater arranged to govern said heater to maintain said lubricant in a iluid condition, a heating means for said generator, and refrigeration demand responsive means for controlling the operation of said motor and said generator heating means, said generator heating means being constructed and arranged to maintain said generator continuously at a temperature such that the same is able to produce refrigerant vapor immediately said control mechanismresponds to a demand for refrigeration.

11. Absorption refrigerating apparatus including a iluid circulator and a driving element therefor sealed within the apparatus, said driving element being positioned in a lubricant which is non-fluid at atmospheric temperatures, means for applying a driving force tosaid driving element and for applying heat to said lubricant at a i'lrst rate which is sufficient to render the lubricant iluid in a substantially fixed period of time and at a second lower rate which Will maintain said lubricant in a fluid condition, refrigeration demand responsive means for energizing said means for applying a driving force to said driving element and for heating said lubricant, and means responsive to a change in the thermal condition of a portion of the apparatus induced by such energization for subsequently changing said heating rate.

12. Absorption refrigerating apparatus including a cooling unit, means for supplying a cooling 'medium to said cooling unit, a motor driven circulator heater assembly including a rotor sealed Y in said apparatus and immersed in a lubricant which is non-fluid at atmospheric temperatures, said motor-circulator heater assembly including means for heating said lubricant at a ilrst rate to render the same fluid and at a second rate to maintain the lubricant fluid, means for simultaneouslyenergizing said cooling medium supply means and said motor-circulator heater assembly to apply heat to said lubricant at said first rate, and means for changing the operation of said assembly to apply heat to said lubricant at said second rate when said lubricant has been rendered fluid.

13. Absorption refrigerating apparatus including a fluid circulator hermetically sealed therein, a driving device for said circulator also sealed with the apparatus, a lubricant sealed within said apparatus and contacting said driving device, said lubricant having a viscosity which is suiiciently high at atmospheric temperatures to prevent normal operation of said driving device, a heater for said lubricant, means for controlling the operation of said heater and arranged to render the same inoperative to heat said lubricant when the lubricant has been heated suiliciently aso'mea to lower its viscosity to a value such that it does not prevent operation of said driving device.

14. In an absorption refrigerating apparatus of the three iiuid type including a generator, a liqueer, an absorber and an evaporator connected in circuit, a fluid circulator, a driving device for said uid circulator, said uid circulator and said driving device being hermetically sealed within said apparatus, a lubricant for said driving device hermetically sealed within said apparatus, said lubricant being sufficiently thick at atmosphemc temperatures to stall said driving device, means for heating said lubricant, and means for rendering said lubricant heating means inoperative to heat said lubricant when said lubricant has been rendered suiciently uid to allow said driving device to operate.

15. In an absorption refrigerating apparatus of the three-fluid type including a generator, a

.within said apparatus, a lubricant for said driving device hermetically sealed within said apparatus, said lubricant being sulciently thick at atmospheric temperatures to stall said driving device, means for heating said lubricant, means for heating said generator, means for rendering said generator heating means and said lubricant heating means operative in response to refrigeration demand and for energizing said driving device, and means for rendering said lubricant heater inoperative to heat said lubricant when said lubricant has been rendered sufficiently fluid to allow said driving device to operate.

16. In an absorption refrigerating apparatus of the three-fluid type including a generator, a liquefier, an absorber and an evaporator connected in circuit, a uid circulator, a driving device for said fluid circulator, said fiuid circulator and said driving device being hennetically sealed within said apparatus, a lubricant for said driving device hermetically sealed within said apparatus, said lubricant being suiiiciently thick at atmospheric temperatures to stall said driving device, means for heating said lubricant, means for heating said generator at a first rate which is suilcient to maintain the same at an operating temperature without the production of refrigerant vapor and at a second higher rate which will cause evolution of vapor in said generator, means for causing operation of said generator heating means at said second rate in response to a` demand for refrigeration, and means for rendering said lubricant heater inoperative to heat said lubricant when said lubricant has been rendered suflciently fluid to allow said driving device to operate.

17. In an absorption refrigerating apparatus of the three-fluid type including a generator, a liquefier, an absorber and an evaporator connected in circuit, a fluid circulator, a driving device for said fluid circulator, said iluid circulator and said driving device being hermetically sealed within said apparatus, means for imposing a stalling load upon said driving device, means for heating said generator, normally inoperative means arranged when operative to render said load imposing means inoperative to impose a stalling load upon said driving device after a time delay, control means arranged to render said generator heating means and said normally inoperative means operative in response to a deasomo@ mand ior refrigeration. and means for retu said normally inoperative means to inoperative condition after the expiration oi said time delay.

18. An hermetically healed absorption refrigerating apparatus including a' boiler, a liqueer, an evaporator and an absorber connected in circuit, a duid circulator hermetically sealed in said apparatus including a driving element which is er, means for heating said lubricant and for applyina a driving ,force to said driving element, control means for governing the energization of said heater and oi said last mentioned means, and means operative when said lubricant is rendered iluid to diminish the rate at which heat is applied to said lubricant to a value sumcient to maintain said lubricant in a uid condition.

DONALD G. S.

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