US2066334A - Refrigeration - Google Patents

Description

Jan. 5, 1937.

F. L. CHASE REFRIGERATION Filed Aug. 31, 1935 s Shets-Sheet 1 Jan. 5, 1937,

F. L. CHASE REFRIGERATION Filed Aug. 31, 1935 3 Sheets-Sheet 2 ;BY Q

ATTORNEYS Jan. 5, 1937. CHASE REFRIGERATION Filed Aug. 31, 1935 3 Sheets-Sheet 3 M v gZZENTOR.

4 m uwhr w 21 v V 8 9 mm V v 8 a Patented Jan. 5, 1937 nrrmcamrron Frederic L. Chase, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application August 31, 1935, Serial. No. 38,800

'19 Claims.

This invention relates to refrigeration and more particularly to a method of preparing the insulation of motor windings, leads, etc., for sealed units of refrigerating systems, and is a continuation in part of application No. 679,923,

filed July 11, 1933. v

Heretofore it has been customary to provide refrigerating systems with sealed units in which the motor and compressor are sealed in a hermetic casing. The electric motor has windings.

leads, etc., which are generally covered with cotton and paper insulation. I have discovered that when such windings, leads, etc., are used in refrigerating systems in which certain circulating agents, such as highly solvent refrigerants and lubricants. are used, and also in which antifreeze solutions such as alcohol are used, certain natural resins, waxes and oils of the cotton insulation are dissolved and are carried along throughout the refrigerating system by these agents. At places where there is a change of phase, or a decided change in'temperature even without a change of phase, these natural resins are likely to be precipitated or deposited. If the 5 passageway is of small dimensions, the accumulations of these resins, waxes and oils may eventually render the refrigerating system inoperative.

For example, in the type of refrigerating system where a relatively long capillary tube is used as the expansion member, and in which a sealed motor-compressor unit is used in which the motor windings, leads, binding tapes, etc., are allowed to come in contact with the circulating agents flowing throughthe system, and in which these circulating agents comprise a fluorine refrigerant, such as C2CI2F4, and lubricants such as mineral oils with or without the use of an anti-freeze medium such as alcohol, I have discovered that the natural resins, waxes and oils in the cotton insulation of the windings, leads, binding tapes, etc., and in paper used, are dissolved and eventually are deposited in the capillary tube, so that, after a short shut-down, such as for defrosting or the like, the capillary passageway is clogged and the system will not refrigerate again without an objectionable service operation.

I overcome these objections by removing substantially all of these natural resins, waxes and oils which are soluble in these agents from the cotton insulation prior to the sealing up of the refrigerating system, and preferably before any of the permanent circulating agents of the system are introduced therein. A suitable way of fore the circulating agents are introduced, with an organic solvent or mixture or series of solvents, and, as one example, the cotton is treated with one or more non-polar solvents, such as toluol, zylol, naphtha or petroleum ether and with one or more polar solvents, such as methyl or ethyl alcohol, with a sufiiciently thorough ap plication and washing action to remove at least enough of these resins, waxes or oils to render them harmless in the system. Thereafter when the system is charged with its permanent circulating agents, the objectionable clogging will not occur.

If desired, the solvents may be purified after the washing operation and used again.

As it is also desirable to remove as much moisture as possible from the motor parts before charging the system with refrigerant, thisflremoval of moisture conveniently may be accomplished simultaneously with one of the treatments above described.

As examples of specific methods and apparatus for practicing my invention, and not by way of limiting the scope of the invention, reference is made to the accompanying drawings for more detailed disclosure of the embodiments now preferred by me.

In the drawings:

Fig. v1 is a diagrammatic representation of a refrigerating system to which my invention may be pp Fig. 2 is a diagrammatic representation of a motor stator which may be used in the system shown in Fig. 1;

Fig. 3 is a diagrammatic representation of an apparatus which may be used for the treatment of motor parts either with the polar or non-polar solvents;

Fig. 4 is a diagrammatic representation of a different apparatus in which the motor parts may be treated with the polar solvent;

Fig. 5. is a diagrammatic representation of a modified form of apparatus for the treatment of motor parts with non-polar solvents; and

Fig.6 is a transverse cross-sectional view of a portion of Fig. 4. A refrigerating system to which my invention may be applied may include, for example, a motor-compressor unit I, preferably of the hermetically sealed type in which both the motor and compressor are contained in a hermetic cas- 2 ingandin whichthemotorwindings. lesds.bindingtapes,etc.,areallowedtocomeincontaet with the circulating agents flowing through the system. The unit I forwardethedrculatlng agents,whichmayineludeavolatilerefrigersnt and lubricant withorwithoutasmallquaniity of alcohol, as hereinbefore described. throughthe lineltoaeondenserifro'mwhenceliquidiiows intothereceiverl. rromthencethereirigerant and/or lubricantflcwsthrough the line I, through an interchanger Iatothe expanslondevicel, whichmaybeoi'theelongatedoriflceorcaulllarycway yu i'romwhencetherefrigerant flows through the evaporator I, where the refrigerant is evaporated and from whence it 'retmnsthroughtheline Itofliemotor-compressorunitl. I

The motoroi'theunit i may'have-a stator which a ilhistratedin Hg. 2.

'lhisstatorincludeswindingstwhichmarhave cotton insulation around the individual wires, asiswellknowmandthewindingsmaybeheld inplacebybindingtapuil. Thewindingsmay, beenergisedbycurrentiiowingthroughtheleads ii, ilandilwhichleashmayhavecottonmsulationaroundthemasiswellknown.

The cottoninsulaticnofthemotorwindings andleadsandthebindingtapqetcembe treated with the solvent orsolve'nh II contained inthetankil,1"lg.3,inanysuitablemanncas bydippingtheminthesolventorsolvents. V Thetreatingoperation forthecottonmybe performed either before the cottm is applied to thewindingsorafteritisappliedtothewindings. Infact,thestatorshowninl'ig.2may,itmlf; besubmergedandwashedinthetankiI. The motor rotor, if of the type requiring treatment mayalsobesimilarlytreated.

'lheapparatusshowninl'ig.3maybeusedto treatthemotorpartswithpolarorncn-polar solvents, itbeing imderstood that preferably dupllcatesetsofapparatmasshowninlimlmay beused, one for the treatment withthepolar solvents and mother with the treatment for the non-polar solvents. 'lhemotorparts,nrchasthe stator and/or rotors-reintroduced intothekettle itwhichisthereattersealed. Thevalves IIand 2! are closed and the solventsupplyvalve It is opened, thus introducing a quantity of solvent into the kettle II suflicienttosubmergethemotor parts. Thereafterthe valve 2! isciosedand inthetank ilmaydrainintothestilll'lfor' purification of the solvent; A suflieient supply of solventis maintainedinthekettletosubmerge the motor parts during the treatment.

The solvent, together with the impurities, with .orwithoutwateristhenheatedinthesflllll byignitingtheburnerii underthecontrolof valve I! which in turn is controlledby the thermostatic' bulb II. The vapors are driven oil through the pipe II to the condenser II, cooled by water circulating through pipe II. The purifledsolventdrainsthrcilghthe ape Ilintothe 'treated,theyareplacedinthebasketiIIwhi receptacleIIi'romwhichitmayberemovedfor reuse, any water present being decanted, or otherwise removed from the solvent.

lnthe'modiflcationshowninrigaiandithe" treatmentwithapoiarsolventmaybeaccom- "plishedinawasherofthetypeticaily depictedin Pig. 4, while thetreatment withthe non-polarsolventmaybeaccomplishedinanap- Fig.5.

Thetreaimentwithapolarsolventmaybe .paratusof'the type in accomplished in any suitable washing machine" For example, as shown in Fig. 4, the stators or rotors are mounted on spindles iII, the stators orrotorsbeingindicated still. Thesespindles aremountedonasuitablerotatingstructureilt whichalsorotatathespindlesandgivesthem a rotary motion. The motor parts are thus dipped,- while rotating, ina body III of polar lorveht, such as methyl orethyl alcohol. The

alcoholisheatedbysteamjacketorthelike III.

The alcohol vapors from this treatment may be inarefluxcondenserlmandthe.

bottoinofthe kettleas indicated. Theiacket III' may be suppliedwith steam for heating purposes through the pipe III having valve III. A suitablesightglass III may alsobe providedin the kettle. ".lhevaporspaoeof the kettle isconnected by a pipe iiiwith a reflux condenser ill. A'

pipeillleadstoaventlineillopentothest- -mosphere andwhiohisprovidedwithavalve III and asight'giassilI having a drainwith Ia. Thepipe iilisalsoconnected withapipe iiI leading to srvacuum pump lila and provided ,withavalve iilandapressuregause lit. 'lhe reflux condenser drains through a pipe III and valve III to a reflux sight glass I22. This sight glass drains through the valved drain III into the sump tank III which in turn is provided with a valved drain III. The steam jacketed kettle III isconnected by the pipe III with a manifold III which in turn is connected with valves and pipes ilI, III, ISI and III which are connected respectively with an oil sump, an oil supply, a solvent supply and a solvent sump.

when the stators orrotcrsareready to the steam jacketed kettle a being heated steam. At this stage, the vacuum valve I closed and the vent valve III is opened. kettle is sealed tightly and the valves iII and III are closed. The valve iII isopen admitting a non-polar solvent, such as toluol,

lmtilitisslightlyabovethebottomofthestator' basket. Thetoluolis'allowedtoboilwhilebeing by'the steamin theiachetuntil its level the stator basket, tbm driving oi! the inthesystem. Thereafter'the vent valve III and the vacuum valve III opened and um imposed. on the kettle. a slight amount of uol is then added by opening valve III until.

vacuum drops to 25 inches mercury, all the allowing the toluol to boil so'that the hot luol vapors come in contact with the stators. The hot toluol vapors drive 01! a large amount of moisture from the stators. During this time of approximatelyainchesmereury the valve I2I is opened and the valve I23, which is maintained normally closed, is intermittently opened to drain the toluol from the water in the sight glass I22. This procedure is repeated introducing toluol into the lower part of the kettle and boiling it off until the toluol which drains into the sight glass I22 appears clear, thus indicating that a large amount of the moisture has been driven off the motor parts. After no substantial moisture isjurther driven oh by toluol vapor, the vacuum valve I I5 is closed and toluol is introduced until it submerges the stators. When the pressure has risen sufliciently, the vent valve H5 is opened and the toluol is boiled for 30 minutes causing the toluol to dissolve the undesirable constituents in the windings. The toluol is then drained from the kettle for approximately 10 minutes after which the stators are again subjected to hot toluol vapors under vacuum to remove any slight traces of moisture remaining. After the kettle has been subjected to a vacuum while the stators are being treated to toluol vapors the second time, and after this last treatment is completed, oil is introduced through the valve I29 until it submerges the stators or rotors: This thoroughly impregnates them with the oil. They may be kept submerged in oil until ready to be assembled in the refrigerating system, thus preventing reabsorption of moisture.

The oil or lubricant with which the windings are impregnated preferably is similar to, or identical with, the oil or lubricant which is to be used permanently in the refrigerating system.

The treatment with the polar solvents, briefly described above, may include a drying operation. It also may include purification of the solvent for reuse. Thus after the stators and/or rotors have been placed on the spindles I06 through the door I50, they are rotated by means of the driving belts I5I. A suflicient amount of heat is provided by means of the jacket I 04, any solvent vapors driven off being collected in the reflux condenser I52 and draining through the pipe I53 to the sump I56. After the washing treatment has been completed, the alcohol remaining in the drum I58 is drained into the sump I54 and thereafter air may be blown by the blower I55 through the heater I56 and through the hollow shaft I5'I into and through the drum I58. The warm air thus introduced into the drum I58 comes in contact with the stators and removes the excess liquid from them before they are removed for treatment with the non-polar solvent.

The solvent gathered in the sump I54 may be purified by draining it through the valve pipe I60 I into the still I6I. Here heat is applied and the alcohol vapors are condensed in the condenser Illa. The condensate drains through the pipe I62 into the sump I63 for reuse, together with any additional supply of solvent which may be introduced into the sump I63 or independently into the drum I58. The solvent in sump I63 may be introduced into the drum I58 through the valve I64. Fig. 6 diagrammatically represents a cross-section of the drum I58.

While I have disclosed embodiments and steps now preferred, it is to be understood that equivalent treatments or steps come within the scope of my invention. While I have disclosed treatment with two or more types of solvents, it is to be understood that a single solvent may be suflicient under certain conditions. Also, while I have disclosed the simultaneous removal of resins, waxes and oils with the removal of water, it is to be understood that such removal of water may ing system in which a sealed motor-compressor unit has an electric motor in contact with the circulating agents of the system, which comprises treating the insulating windings of the motor prior to the charging of the system with a polar solvent and with a non-polar solvent to remove natural resins, waxes and oils, and thereafter charging'the system with circulating agents and sealing said system. i

2. The method of manufacturing a refrigerating systemin which a sealed motor-compressor unit has an electric motor in contact with the circulating agents of the system, which comprises treating the insulating windings of the motor prior to the charging of the system with a polar solvent and with a non-polar solvent and heating said windings to remove moisture and natural resins, waxes and oils, and thereafter charging the system with circulating agents and sealing said system.

3. The method of. manufacturing a refrigerating system in which a sealed motor-compressor unit has an electric motor in contact with the circulating agents of the system, which comprises treating the insulating windings of the motor prior to the charging of the system with a polar solvent and with a non-polar solvent and heating said solvents and windings to remove moisture and natural resins, waxes and oils, and thereafter charging the system with circulating agents and sealing said system.

4. The method of manufacturing a refrigerating system in which a sealed motor-compressor unit has an electric motor in contact with the circulating agents of the system, which comprises treating the insulating windings of the motor prior to the charging of the system with a hot solvent vapor and with a hot solvent liquid to remove moisture and natural resins, waxes and oils, and thereafter charging the system with circulating agents and sealing said system.

5. The method of manufacturing a refrigerating system in which a sealed motor-compresthe circulating agent of the system, which comprises treating the insulation of the motor prior to the charging of the system 'with a hot solvent to remove moisture and natural resins. waxes and oils, and thereafter charging the system with a circulating agent and sealing said system.

6. The method of manufacturing a refrigerating system in which a sealed motor-compressor unit has an electric. motor in contact with the circulating agents of the system, which comprises treating the insulation of the motor prior to the charging of the system with a solvent to remove natural resins, waxes and oils, thereafter impregnating the insulation with oil, and thereafter charging the system with a circulating agent and sealing said system.

7. A refrigerating system in which a sealed motor-compressor unit has an electric motor in contact with the circulating agents of the system and in which the cotton electrical insulation of said motor has been treated, prior to the charging of the system, to remove natural resins.

motor-compressor unit has an electric mdtor in contact'with the circulating agents of the system and in which the cotton electrical insulation of said motor has been treated, prior to the charging of the system, to remove natural waxes.

' 9. A-refrigerating system in' which a sealed motor-compressor unit has an electric motor in contact with the circulating agents of the system and in which the cotton electrical insulation of said motor has been treated, prior to the charging of the system, to remove natural resins, waxes and oils.

10. The method of manufacturing a refrigerating system in which a sealed motor-compressor. unit has an electric motor in contact with the circulating agents of the system which comprises treating the insulating windings of the motor prior to the charging of the system to remove natural resins, and thereafter chargi the system with the circulating agents and sealing said system.

11. The method of manufacturing a refrigerating system in which a sealed motor-compressor unit has an electric motor in contact with the circulating agents of the system which comprises sor unit has the stator of the electric motor in system.

- 13. The method of manufacturing a refrigerating system in which a sealed motor-compressor unit has the stator of the electric motor in contact with the circulating agents of the system which comprises covering'the windings of said stator with cotton electrical insulation, bringing said stator in contact with selective solvents adapted, to remove natural resins from said cotton, charging said system with the circulating agents of the system and thereafter sealing said 14. 'lzhe method of manufacturing a refrigerating system in which a sealed motor-compres- 'adaptedtoremovenaturalwaxesfromssidcotton, placing said statorinsaidsys tem, charging said systemwiththeeirculating agentsofthesystemandthere'aftersealingsaid 15. The method of manufacturing a'refrigeratingsysteminwhichasealed motor-compres- "s'or unithasthe statorottheelectrle motorin contactwiththecirculatingagentsofthesystem whichcomprisescoreringthewindingsofsaid stator with cotton electrical insulation, bringing said stator in contact with selective solvents adaptedtoremovenatm'aloilsfromsaidcotton,

placingsaidstatorinsaidrefrigeraflngsystem.

chfl n saidsystemwiththeeirculatingagents ofthesystemandthereaftersealingsaidsystem. 16. A refrigerating systemin which a sealed motor-compressor unit has an electric motor in contact with the circulating agents of the system and in which the circulating agents of the system flow through a relatively long capillary tuheand in which the cotton electrical insulation of said motor has been treated, prior to the chargingofthesystemtoremovenaturalresins.

1'1. A refrigerating system in which a sealed motor-compressor unit has an electric motor in contact with the circulating agents of the system andinwhichthecirculatingagentsofthesystem flowthrougharelativelylongcapillarytubeand' in which the cotton electrical insulation of said motorhasbeentreatedprior tothecharging of the' system, to remove natural waxes.

18. A refrigerating system in ,which a sealed niotor-compressor unit has an electric motorin contactwiththecirculatingagentsofthesystem andinwhichthecirculatingagentsofthesystem flow through a relatively long capillary tube and in which the cotton electrical insulation of said motorhasbeentreated,priortothechargingof the system, to remove natural oils.

19. A refrigerating system in which a sealed motor-compressor unit has an electric motor in contactwiththedrculatingagentsofthesystem andinwhichthecirculatingagmtsofthe systemfiowthroughareiativelylongcaplilaryv.

,tubeandinwhichthecottonelectricalinsulation of said motor has been treated,"prior to the chargingofthesystemtoremovenaturalresins and-oils:

- IREDIRICLCHABE.

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