US1885837A

US1885837A - Refrigerating apparatus and means for lubricating same

Info

Publication number: US1885837A
Application number: US351372A
Authority: US
Inventors: Herbert C Kellogg; Edward M May
Original assignee: Individual
Current assignee: Individual
Priority date: 1929-03-30
Filing date: 1929-03-30
Publication date: 1932-11-01
Anticipated expiration: 1949-11-01

Description

1933 H. c. KELLOGG ET AL L8 9 REFRIGERATING APPARATUS AND MEANS FOR LUBRICATING SAME Filed March 30, 1929 2 Sheets-Sheet J.

1932' H. c. KELLOGG ET AL 1,885,337

REFRIGERATING APPARATUS AND MEANS FOR LUBRICATING SAME Filed March 50, 1929 2 Sheets-Sheet 2 wwwwfia' /WC KW AWA/EK Patented Nov. 1, 1932 I UNITED MRBEBT G. KELLOGG AND EDWARD ELMAY, F DETROIT, MICHIGAN, ASSIGNOBS T0 GLEN 1. COWAN, 0F DETROIT, MICHIGAN; GRACE A. COWAN EXECUTBIK OF SAD GLEN P. OOWAN, DZEKEEASIEZD-v BEFBIGERATING APP was am) as For. nunnrcarme same Application filed March 80, 1329. Serial No. 351,372.

This invention relates to refrigerating apparatus in which a gaseous refrigerating fluid is cyclically condensed and liquefied and again evaporated from the liquid to the gaseous state with the accompanying absorption of heat. The improvements have to do more particularly with the means or apparatus for evaporating the liquid refrigerant to the gaseous state and to the relations of that apparatus to the means by which the refrigerant is condensed and liquefied. The application constitutes a continuation in part of our copending application Serial No. 295,- 174, filed July 25, 1928, in which we claim the heroin disclosed means for returning at least some extent, soluble in the liquid refrigerant employed and having improved means for maintaining a suitable body of liquid refrigerant in the evaporator and returning accumulated lubricant from the "evaporator to the refrigerant pump or. condenser.

Another object of the invention is the provision of a refrigerating apparatus employing an evaporator of the flooded type and-a re rigerant in which the liquid lubricant is more or less soluble, which is adapted under varying heat loads, i. e. varying rates of heat transfer, to maintain the lubricant in the evaporator at a relatively small and constant amount and at the same time to revent discharge of refrigerant in the liqui state from the evaporator to the compressor.

A further object of the invention is the provision of an evaporator of the flooded type having an improved float valve for con trolling the admission of liquid refrigerant to the evaporator, the valve mechanism, in-

Another object of the invention is the prov vision of an improved method of lubricating the working parts of mechanical refrigerating apparatus of the type employing afiooded evaporator.

. Other objects of the invention more or less incidental or ancillar to the foregoing will appear in the following description setting forth some of the preferred forms of construction and methods of carrying out the infrigeration apparatus embodying the inven- .5

tion, the invention being shown in conjunc tion with a refrigerator of the domestic type.

Fig. 2 is an enlarged section on the line 22, Fig. 1, showing the cooling unit of the refrigerator with the tray of the brine tank removed.

Fig. 3 is a section on the line 3-3, Fig. 2. Fig. 4 is a vertical section through an evaporator of modified construction adapted for use in lieu of that illustrated in Figs. 1 to 3.

Fig. 5 is a section on the line 5-5, Fig. 4;-

Referring in detail to the construction illustrated, and first to the form of apparatus illustrated in Figs. 1, 2 and 3,- 1 designates as an entirety an evaporator of the flooded type which is associated with a brine tank 2 to form a cooling unit which is shown mounted in the usual manner in a refrigerator 3 of the household type. 4 is a refrigerant compressor which ma be of any suitable known form of constructlon and 5 is an electric motor by which the compressor is driven through a belt 6. 7 is a condenser which may be cooled by water circulation or in any other known manner. A pipe or conduit 8 connects the inlet or suction opening of the compressor 4 with the discharge passage of the evaporator 1; a conduit 9 connects the discharge passage of the compressor with the condenser 7 and a conduit connects the condenser 7 with the inlet of the evaporator 1. The operation of the compressor in apparatus of this character is usually intermittent and in the construction illustrated it is controlled by an automatic switch 11 which may be of any suitable known construction and which is actuated by the pressure of the gaseous refrigerant in the suction conduit 8 with which the switch 11 communicates through a conduit 12. 13 is the usual manual switch for throwing the entire apparatus into or out of operation.

The present invention has to do particularly with the construction and functioning of the evaporator 1. In the construction illustrated in Figs. 1, 2 and 3, the evaporator 1 comprises a shell 14 made of two

sections

14 and 14 of sheet metal which are stamped or drawn into the roughly oval or elliptical form shown in Fig. 3 and which are joined together by the horizontal flanged seam 15- which is brazed or soldered to render the joint gas tight. The top wall of the shell is formed with an opening in which is hermetically secured a fitting 16-to receive a threaded refrigerant inlet tube 17 which depends within the evaporator. The oint between the tube 17 and the fitting 16 is rendered gas tight 4 by a washer or gasket 17 c of soft metal or other suitable material which is clamped between the fitting 16 and a shoulder formed by the head 17 a of the tube 17. The said head 17 is formed with a threaded horizontal opening 17 to receive the end of the refrigerant conduit 10.

A valve to control the passage through the inlet tube 17 is' secured to the lower end i of the said tube. The valve comprises a body member 18 which fits nicely within the lower end of the tube 17 and is formed with a shoulder 18 to engage the lower end of said tube. The valve body 18 is formed with an axial passage having an upper part ofone diameter and a lower part of larger diameter so as to form intermediate its ends a seat for a needle valve 19 whi h is preferably formed from stock approximately triangular in cross section and has a depending stem 19* of reduced, diameter. A flanged and threaded fitting 20 engages the threaded lower end of the tube 17 and servesto secure the valve body 18 tightly in position in the lower end of the tube and also secures the needle valve 19 in the valve body, with the stem 19 of the valve projecting downward through a hole in the lower end of the fitting 20, said hole being larger than the stem so that liquid flowing through the tube 17 and passing the valve 19 has free outlet through the lower end of the fitt ng 20. The upper end of the valve body 18 has a reduced extension or nipple to which is secured a tubular metal gauze filter 21.

, S urrounding the depending tube 17 is an inverted annular cup-shaped float 22 provided with a central tubular part 22*. v This float has a metal strip 22 secured to the lower end of its cylindrical tubular part 22*, so as to engage the stem 19 of the valve proper and is discharge amas-av press the valve against its seat when the float is lifted.

The upper wall of the shell 14 has a second opening to receive a fitting 23 which carries a depending discharge tube 24 and an elbow 24 which is connected to the suction conduit 8 leading to the compressor. Below the fitting 23 is an open-topped receptacle 25 which is roughly crescent shape or kidney shape in horizontal outline and which is suspended from the fitting 23 by a support 26, the position of the receptacle 25 being such that the lower end of the tube 24 is somewhat above the bottom of the receptacle.

The evaporator shell contains a body 27 of liquid refrigerant or, more strictly speaking, combined refrigerant and lubricant. The open bottom side of the float 22 is submerged in the liquid refrigerant, or combined refrigerant and lubricant and, with gas trapped in the float, the latter has ample buoyancy. With the accumulation of pressure in the evaporator shell the liquid therein tends to rise in the float cavity above the bottom edge of the float but not to as high a level as the liquid attains outside of the float. In the operation of the apparatus some evaporation of the liquid refrigerant always occurs directly beneath the float and some of the gaseous refrigerant thus formed finds its way upward into the chamber of the float thus assuring adequate buoyancy at all times.

In the construction illustrated, the evaporator shell-14 is mounted in the top wall of a brine tank 28 with the lower part of the evaporator shell submerged in the brine in said tank, the brine tank being in detail of any suitable construction. As shown it. is provided with a reentrant chamber to receive a tray 28- for freezing water or foods.

The evaporator, as well as the other parts of the apparatus, is adapted for the use of various refrigerants among which may be mentioned by way of example sulphur dioxide, methyl chloride and ethyl chloride.

Lubricating oils which are suitable for the lubrication of the compressor are more or less soluble in most if not all of the preferred and commonly used refrigerants such as those mentioned. Thus suitablemineral oil lubricants are partially soluble in sulphur dioxide and are completelysoluble in methyl chloride and ethyl chloride, at least within 1 the limits of the proportions of oil and refrigerant normally employed. On account of this solubility, the liquid lubricant which is'scrubbed ast the compressor piston and (i into the condenser, dissolves in the refrigerant liquefied in the condenser and passes with the latter in' solution into the evaporator. Then when the refrigerant is evaporated'the oil is left and accumulated in the evaporator so that provision must be made for its return to the compressor.

Assuming that the apparatus has been assembled and a suitable amount of refrigerant, such for example as sulphur dioxide, together with a suitable amount of lubricant, such for example as a suitable mineral oil, have suitably charged into the system, the operation of the apparatus is as follows. Heat absorbed through the wall of the evaporator causes evaporation of liquid refrigerant therein with resultant rise of the pressure in the evaporator and in the return or suction conduit 8, which rise in turn causes the operation of the switch 11 to close the electric circuit and start the operation of the compressor 4. The compressor draws the gaseous refrigerant from the evaporator thus reducing the pressure therein and increasing the rate of evaporation of the liquid refrigerant in the evaporator. When the level ofthe l quid in the evaporator falls as a result of the evaporation, the float 22 is lowered and the valve 19 permitted to move away from its seat and admit additional liquid refrigerant, the float thus serving to au tomatically maintain a nearly constant amount of liquid in the evaporator. The evaporation is, of course, accompanied by the usual coolin effect upon the evaporator and the surroun ing space cooled by it, which in the case illustrated is the brine tank and the interior space of the refrigerator 3. As the temperature of the evaporator is lowered by the operation of the compressor the pressure in the evaporator is also correspondingly lowered and when the pressure reaches a predetermined point the switch 11 is opened to stop the operation of the compressor. The operation thus described constitutes the usual cycle of operations of apparatus of this general character. 7

However, the detailed operation within the evaporator during the cycle is quite distinctive and, as far as we are aware, peculiar to our improved form of apparatus. When the operafion of the compressor is started it begins at once to reduce the pressure in the evaporator with resultant starting of relatively rapid evaporation within the mass of the liquid refrigerant in the evaporator. lhis evaporation is accompanied by the formation of bubbles of gaseous refrigerant within the mass of the refrigerant which have the efl'ect of raising the level'of the liquid in the evaporator, this eflect being most marked at the beginning of the operation of the compressor because it takes an appreciable amount of time for the bubbles formed in the lower part of the mass of refrigerant to rise through the liquid and escape from its upper surface. Consequently when the compressor is started the level of the liquid in the liquid when refrigeration is not going on, but the highest parts of the agitated surface of the liquid remain considerably above the said normal level; The temporary rise of the level of the boiling liquid to a maximum height before the gaseous refrigerant begins to escape from the surface of the liquid is naturally more marked where the depth of the body of liquid refrigerant in the evaporator is relatively great so that a longer interval of time is required for the gas formed in the lower part of the body of liquid to rise through said body and escape from its upper surface. The float 22 is designed to maintain a normal level of the liquid in the evaporator at such a distance below the top edge of the receptacle 25 that theincrease in the volume of the boiling liquid at the beginning of the operation of the compressor will carry the level of the liquid up nearly to or even somewhat above the said top edge or rim of the receptacle 25. When the level of the liquid is thus carried above the rim of the receptacle it is clear that some'of the liquid will spill over into the float and be drawn through the tube 24 and suction conduit 8 back to the compressor. This latter action is more particularly feasible and de sirable when a refrigerant is employed in which the lubricant is only partially soluble and which is of a greater specific gravity than the lubricant so that the excess lubricant accumulating in the evaporatorrises and forms a distinct stratum at the top of the body of liquid so that 011 only spills over into" the float on the temporary rise of the liquid level as above described. By properly fixing the height of the rim of the receptacle 25 above the normal liquid level (that is the level when evaporation is not goingon), for a given depth of liquid refrigerant in 'the evaporator and a given heat load, the rise of the liquid refrigerant nnderlyingthe stratum of lubricant to a level above the rim of the receptacle is avoided while onlyexcess lubricant accumulated in the'evaporator is discharged into the receptacle and returned to the compressor in the manner described. When a refrigerant and a lubricant are used that are mutually soluble in all usable proportions thereof, it is preferable that the maximum liquid level attained be somewhat below the rim of the receptacle 25. Whether the maximum liquid level be above or somewhat below the rim of the receptacle. a discharge of lubricant into the receptacle and thence back to the vcompressor is attained in a manner which will now be explained.

Assuming, for example; that the refrigerant is sulphur dioxide and that the lubricant is a suitable mineral oil of lower specific gravity than the liquid refrigerant, with the normal liquid level in the vaporizer chamber 14 somewhat above the middle of the float,

as indicated in Fig. 2, when the compressor is started and evaporation begins in the evaporator, if the float has been designed to secure overflow of lubricant into the receptacle 25, the increase in volume of the liquid in the evaporator due to submerged bubbles will raise the liquid levelv temporarily slightly above the rim of the receptacle so that some of the stratum of oil floating on the liquid S0 will flow into the receptacle and be drawn by the suction of the compressor-through the tube 24 and conduit 8 back to the compressor, as previously described. Then as soon as the bubbles of gasified refrigerant begin to break through the surface of the liquid, the average level of the liquid will fall again approximately to the normal level indicated in Fig. 2, though by reason of the agitation of the liquid the uppermost surface thereof attains somewhat higher levels. Thereafter, as, evaporation continues, the bubbles of gasified refrigerant break through the surface of the liquid forming a mass of bubbles or foam which may build up until it rises above the rim of the receptacle, whereupon some of it is carried over into the receptacle from which it is drawn by the suction of the compressor.

When the liquid refrigerant and the lubricant employed are completely mutually soluble, as where methyl chloride, for example, and a suitable oil are used, we ordinarily prefer so to design the float and the receptacle that the maximum level which the liquid attains during ebullition is slightly below the rim of the receptacle. In this case as the bubbles formed by the gasified refrigerant rise through the body of liquid and emerge from the surface thereof they form a mass of bubbles or foam which builds up in height until it rises above the rim of the receptacle, whereupon some of it is carried over into the receptacle and drawn back to the compressor in the manner described above. In this manner there is passed over the rim of the receptacle liquid which consists chiefly of the liquid forming the walls of the bubbles and which is practically all lubricant since the liquid refrigerant does not have sufiicient viscosity and surface tension to form the walls of the bubbles breaking through the surface of the liquid in the manner described. In other words the formation of the bubbles incident to the evaporation appears to have a selective effect on the oil with its resultant separation from the mass of the liquid. Furthermore.

any slight amount of liquid refrigerant that may be dissolved in the lubricant forming the foam has ample opportunity to evaporate 'before it enters the float and is drawn out through the suction tube 24.

It is to be understood that the apparatus can be operated in the manner last described with the maximum liquid level below the rim of the receptacle when sulphur dioxide and oil are employed as well as when refrigerants such as methyl chloride or ethyl chloride are employed; indeed we ordinarily prefer to sooperate the apparatus regardless of the refrigerant used when the bath of liquid refrigerant in the evaporator is relatively shal- 7' low, since in such cases, the momentary rise of the liquid level at the beginning ofthe evaporation is not greatly above the level maintained as the evaporation continues.

.A variation of the above described operation that occurs under some conditions is to be noted. That is to say, where a refrigerant is employed in which the lubricant has a limited solubility, and particularly when active evaporation is not going on, bubbles from time to time rise through the liquid in theevaporator and burst through the surface of the liquid with more or less explosive force and project small quantities of lubricant upward from the said surface. Some of the 35 lubricant thus thrown up from the surface of the bath falls over into the 'wide opening afforded by the receptacle and thus finds its way back to the compressor.

It will be observed that the refrigerant evaporated from the body of liquid in the evaporator, in being drawn from the evaporator, first passes over the rim of the receptacle and into the latter, whenceit is wit-h drawn through the tube 24 and suction conduit 8. It thus appears that the rim of the receptacle constitutes what may be considered the primary inlet opening of the discharge passage of the evaporator. Since the receptacle rim has a very long perimeter, in com-' parison with the circumference of the discharge tube 24, the velocity of the gas flowing over the rim and into the receptacle is relatively low. This feature obviates entrainment by the gas of the boiling liquid which attains levels nearly up to the rim of the receptacle. Such entraining effects of a streamof gas upon a liquid are quite marked where the velocity of the gas is high, as is evidenced by the fact that the action of the gas entering the lower end of the tube 24 at relatively high velocity is to keep the receptacle practically completely empty of liquid notwithstanding the fact that the lower end of the tube 24 is substantially above the. bottom of the receptacle. It is obvious that the long perimeter of the receptacle rim makes it possible for a relatively large amount of lubricant to flow into the receptacle quickly even if the level of the lubricant is raised but a little above therim. The large area of the top opening of the receptacle, furthermore, presents ample opportunity for the lubricant thrown up by bubbles breaking through the surface of the liquid to fall into the receptacle in a manner previously described.

In Figs. 4 and 5 we have shown a modified form of the evaporator of the system. In this latter construction there is an evaporator shell 29 somewhat oval or elliptical in horizontal section, as indicated in Fig. 5.. The lower part of this evaporator projects downward through the top wall of a brine tank which is of the same character as the brine tank of the first. described evaporator. The top wall of the evaporator shell is provided with a fitting 31 into which is screwed a depending tube fitting 32 which carries a needle valve 33 at its lower end and serves to guide the inverted cup float 34. The

parts

32, 33 and 34 and additional immediately associated parts shown in Fig. 4 being like the corresponding parts of the evaporator shown in Fig. 2. The fitting 32 is adapted to connect with the'liquid refrigerant supply pipe 10 of the system. In this last construction, however, there is an open topped receptacle 35 in the evaporator difiering from the relit) ceptacle in the first described evaporator. The receptacle35 in the second evaporator has a bottom wall 35" and an upstanding side wall 35 which is curved to conform to the adjacent wall of the float 34. At its opposite edge the bottom wall 35 is attached to the side wall of the shell 29 so that the latter in effect constitutes a side wall for the receptacle 35, the latter beingcrescent shaped in horizontal section, as shown in Fig. 5. The side wall of the shell 29 is then apertured to receive a pipe fitting 36 which is adapted to be connected with the suction conduit 8 of the system. The fitting 36 affords a discharge outlet for the receptacle 35 at the bottom thereof through which liquid can flow by gravity if the evaporator is disposed at the highest point of the refrigerant circulating system, as shown in Fig. 1.

The operation of the evaporator shown in Figs. 4: and 5 is the same as the operation of 5 the evaporator shown in Figs. 2 and 3, ex-

cept that the liquid lubricant which is separated from the liquid mass in the evaporator and delivered into the receptacle 35 can run freely by gravity into the suction return line 8 of the system. Accordingly the operation of the last described construction will be understood without further description.

From what has been said in the foregoing description it will be apparent that the height to which the side wall of the lubricant receptor should rise abovethe normal, quiescent level of the liquid in the evaporator in order to insure separation of the lubricant from the liquid refrigerant and discharge of the sepa rated lubricantfrom the evaporator, must be determined, in the design of any specific apparatus, in relation to other factors which will vary for different designs. As noted earlier in the description, such factors include particularly the relative depth of the liquid refrigerant in the evaporator and the heat load (rate of heat transfer) to be .carried' by the evaporator. The heat load, in turn, depends upon the size or area of the evaporator walls contacted by the liquid refrigerant,

the capacity of the compressor, etc. When the heat load is to be widely variable, the maximum rate of heat transfer is, of course, to be taken into account in determining the height of the receptor walls, as well as the proportions of other parts of the evaporator structure. Such considerations will enable the designer to estimate roughly the height of the receptor wall for any specific apparatus and if, on trial of the apparatus, such height proves too great or too small to effect the desired separation and discharge of lubricant, it can be altered to give the desired result. In such trial of a newly designed evaporator the functioning of the oil return can readily be checked by making a short section of the evaporator discharge line of suitable glass tubing, the passage of oil or of mixed oil and liquid refrigerant being clearly visible and distinguishable through the glass wall of the tube.

It is to be observed that the mechanical agitation of the liquid in the evaporator during evaporation, particularly in the uppermost stratum of the liquid, varies with the amount of oil in the liquid, the mechanical agitation due to the bubbling being greater when the proportion of oil present is greater. Thus,

there is in effect an automatic control of the rate of discharge of lubricant from the evaporator, because when the amount of lubricant in the evaporator increases the resultant increase in the mechanical agitation due to theebullition increases the rate at which the mass of bubbles or foam consisting of lubricant and gas forms and builds up from the surface of the liquid and, consequently, the rate at which excess lubricant is discharged into the recep-.

tacle. Our improved method of separating the lubricant from the refrigerant in the evaporator and discharging it from the evaporator to be returned to the compressor, by taking advantage of the inherent variation in the rate of foam formation with varying proportions of lubricant, enables us, under all working conditions, that is, under varying rates of heat transfer, with our improved apparatus to maintain a relatively low percent age of lubricant in the evaporator without ma the evaporator along with the lubricant.

risk of discharging liquid refrigerant from This is true both in the case of refrigerants,

such as sulphur dioxide, in which lubricant is partially soluble and also in the case of refrigerants, such as methyl chloride and ethyl chloride, in which the lubricant is more high-v ly or completely soluble. This is a matter of I V importance.

very considerable practical Thus, when a refrigerant such as sulphur dioxide is used we are enabled to operate the evaporator with a relatively thin stratum of lubricant on the refrigerant and largely avoid the difficulty incident to a thick stratum of lubricant, namely, that the theoretical pressure-temperature relation of the refrigerant methyl chloride, in which the lubricant is cal pressure-temperature relations'of .the refrigerant in setting the pressure operated switch which controls the operation of the compressor to maintain the desired temperature in the evaporator. Furthermore. the very fact that our improved method and apparatus maintains a lower concentration of lubricant in the refrigerant lowers the varia-- tion of the concentration, thus rendering the pressure-temperature relation of the liquid in the evaporator more constant. Similarly, when use is made-of refrigerants, such as fully soluble, the low concentration of lubricant which we are able to maintain in the evaporator avoids the diiliculty incident to high concentration of lubricant that the latter raises the boiling point of the refrigerant and correspondingly reduces the capacity and efficiency of the compressor. Furthermore, as in the case of a refrigerant such as sulphur dioxide, the fact that a low concentration of lubricant is maintained lowers the variation of concentration and makes possible more uniform pressure-temperature relations for the liquid in the evaporator.

. Our improved type of float has the marked advantage that its buoyancy is aifected to a minimum extent by variations in the specific gravity of the liquid in which it is partially submerged. This is due to'the fact that the float has upright cylindrical sides so that when the specific gravity of the liquid is reduced by the ebullition the increased depth of the submergence of the float causes a larger increase in the displacement,to compensate for the lower specific gravity of the liquid, than could be secured with a previously used spherical or horizontal cylindrical float normally submerged to its median plane. Furthermore, our unproved form of float has rel- -atively great buoyancy and lifting power.

This is due to several things. It is due in part to the fact that the float is immersed partly in gas and partly in liquid, that is to say, in two fluids of widely different specific gravities, whereas in the case of the closed floats of spherical or horizontalcylindrical form heretofore commonly used in V flooded evaporators for controlling the level thereon, the specific of the liquid sulphur dioxide refrigerant upon which the excess lubricant floats, the float has been immersed wholly in liquid, that is, partly inthe liquid sulphur dioxide and partly in the stratum of oil floating ravities of these two 1i uids diflering relatively little-from each other. The relatively great buoyancy of our float is further due to the fact that the float can have a large displacement volume and yet be relatively light in weight. This is'possible because the float is open and its walls are never subjected, as are closed floats, to unbalanced gas pressures in the evaporator, so that the walls can be made of relatively thin metal. This is a matter of considerable im portance when it is considered that the gas pressures in such evaporators vary all'the way from about 14 pounds below atmospheric pressure when the s stem is being exhausted preparatory to c arging with refrigerant, upward to about 100- pounds above atmospheric pressure when the evaporator is subjected to summer temperatures during shipment.

.It is obvious that our improved form of float can be fabricated with a minimum expense for material and labor.

The float valve also is exceedingly simple in construction and reliable in operation. It will be observed that the depending inlet tube, the float valve carried by the lower end of the said tube and the filter which in turn is carried by the body of the valve, are assembled as a unit and can with the greatest ease be inserted into and removed from the evaporator shell as a unit. This very greatly facilitates the servicing of the evaporator. The fact that with our improved form of construction the float has no positive connection with the needle valve, as by links, levers or the like, both reduces the cost of producing the parts, facilitates their assembly, and minimizes wear and tear and the corresponding troubles in operation. However it is to be observed that insofar as some of the broader aspects of the float construction are concerned, the invention is not limited to a construction in which the float actuates the valve directly without the interposition of an arm or lever.

In connect-ion with the foregoing description and certain of the claims it will be understood that in characterizing the receptacle in the evaporator as having a top opening of large area or relatively long horizontal perimeter, those terms are employed in comparison with the refrigerant discharge openings of prior evaporators, which have commonly been comparable in size to the refrigerant discharge or suction duct and, of course, the terms are used with regard to the previously explained functions performed by the large primary inlet of the discharge conduit, as well as the obvious function of readily and effectively receiving the lubricant lifted, in the ways above described, by evaporation occurring in the body of refrigerant.

In the foregoing description and in the drawings, we have presented two of the preferred forms of embodiment of our invention, but, from what has been said, it will be obvious that the embodiment of our improveand deliver the liquefied refrigerant tothe' evaporator to withdraw refrigerant ments may vary widely within the scope of our invention as defined in'the appended claims. For example, it is obvious that the receptacle provided in the evaporator may take a wide variety of forms and may be fixed in position in a great variety of ways. It is also clear, insofar as some of the broader aspects of the invention are concerned, that any suitable means whatsoever may be provided for maintaining the normal level of the body of refrigerant in the evaporator,

What we claim is: v

1. In refrigerating apparatus, the combination of an evaporator of the flooded type; a compressor having its inlet connected to the evaporator to wlthdraw refrigerant gas "therefrom; a condenser connected to receive compressed refrigerant from the compressor evaporator; a body of refrigerant in 'the closed system; liquid lubricant in the closed system of lower specific gravity than the liquid refrigerant and soluble to a limited extent in the latter; means for intermittently driving the compressor; a receptacle secured in fixed position in the evaporator and having an inlet for lubricant and refrigerant gas of relatively long horizontal perimeter; a discharge duct leading from the said receptacle to the suction conduit of the compressor; and means associated with the evaporator for controlling admission thereto of the liquid refrigerant and maintaining in the evaporator a normal liquid level at a distance below the said inlet of the receptacle such that the intermittent rise of said level when'the compressor is intermittently started causes discharge into the receptacle of liquid lubricant from the top of the body of liquid in the evap- '1 orator without such discharge of liquid refrigerant.

2. In refrigerating apparatus, the combination of anevaporator of the flooded type; a compressor having its inlet connected to the as therefrom; a condenser connected to receive compressed refrigerant from the compressor and deliver the li uefied refrigerant to the evaporator; a ho y of refrigerant in the closed system; liquid lubricant in the closed system of lower specific gravity than the liquid refrigerant and soluble'to a limited extent in the latter; means for intermittently driving the compressor; a receptacle secured in fixed position in the evaporator an having an inlet for lubricant and refrigerant gas of relatively long horizontal perimeter; a discharge duct leading from the said receptacle to the suction conduitof the. compressor, said duct having its inlet disposed at a point relatively remote fromithe boundary of the said inlet of the said receptacle; and means associated with the vaporizer for controlling the admission thereto of liquid refrigerant and maintaining in. the evaporatora normal liqthe receptacle such that the intermittent rise -uid level at a distance below the said inlet of of said level when thecompressor is intermittently started causes discharge into the receptacle of liquid lubricant from the top a compressor having its inlet connected to p the evaporator to withdraw refrigerant gas therefrom; a condenser connected to receive compressed refrigerant from the compressor and deliver the liquefied refrigerant to the evaporator; a body' of refrigerant in the closed system; liquid lubricant in the closed system of lower specific gravity than the liquid refrigerant and soluble to a limited extent in the latter; means for intermittently driving the compressor; a receptacle secured in fixed position-in the evaporator and having an inlet for lubricant and refrigerant gas of relatively long horizontal perimeter and an outlet through which lubricant'can' flow by gravity into the connection leading to the inlet ofuthe compressor; and means associated with the evaporator for controlling admission.

thereto of the liquid refrigerant and maintaming in the evaporator a normal liquid level at a distance below the said inlet of the receptacle such that the intermittent rise of said level when the compressor is intermittently started causes discharge into the receptacle of liquid lubricant from theto of the body of liquid in the evaporator wit out such discharge of liquid refrigerant. v

4. In refrigerating apparatus, the combination of an evaporator of the flooded type; a compressor having its inlet connected to the evaporator to withdraw refrigerant gas therefrom; a condenser connected to receive compressed refrigerant from the compressor and deliver the liquefied refrigerant to the evaporator; a body of refrigerant in the closed system; liquid lubricant in the closed system of lower specific gravity than the liquid refrigerant and soluble to a limited extent in the latter; means for intermittently driving the compressor; a receptacle secured in fixed position in the evaporator and having an inlet for lubricant and refrigerant gas of relatively long horizontal perimeter and an outlet through which lubricant can flow by gravity into the connection leading to the inlet of the compressor, the said outlet being disposed at a point relatively remote from the boundary of the said inlet of r the said receptacle and means associated with the vaporizer for controlling admission thereto of liquid refrigerant and maintaining in the evaporator a normal liquid level at a distance below the said inlet of the receptacle such that thecintermittent rise of said level when the compressor is intermittently started causes discharge into the receptacle of liquid lubricant from the top of the body of liquid in the evaporator without such discharge of liquid refrigerant.

5. In a' refrigerant evaporator of the flooded type adapted for use in refrigerating systems in which the working parts of the apparatus are lubricated by liquid lubricant that is of lower specific gravity than the liquid refrigerant and'soluble to at least some extent in the liquid refrigerant, the combination of an evaporator casing having an inlet for liquid refrigerant and an outlet for gaseous refrigerant adapted'to-be connected with the suction side of a/refrigerant compressor; a receptacle secured in fixed position in the evaporator and having a top opening of large area and an outlet through the outlet of the evaporator casing, the said receptacle being disposed in relation-to the outlet of the evaporator casing so that lubricant can flow by gravity from the receptacle through the said outlet; and means for controlling admission of liquid refrigerant to the casing and maintaining therein a normal liquid level at such a distance below the top opening of the said receptacle that when lubricant in the casing is lifted by ebullition from the body of liquid therein it will fall into the said receptacleseparate from the liquid refrigerant in the evaporator.

6. In a refrigerant evaporator of the flooded type adapted for use in refrigerating systems in which the working parts of the apparatus are lubricated by liquid lubricant that is of lower specific gravity than the liquid refrigerant and soluble to at least some extent in the liquid refrigerant, the combination of an evaporator casing having an inlet for liquid refrigerant and an outlet for gaseous refrigerant adapted to be connected with the suction side of a refrigerant compressor; a receptacle secured in fixed position in the evaporator and having atop opening of large area and an outlet through the outlet passage of the evaporator casing, said outlet being disposed at a point remote from the boundary of the said top opening of the receptacle and said receptacle being disposed inrelation to the outlet opening of the casing so that lubricant can flow by gravity from the receptacle through the said outlet; and means for controlling admission of liquid refrigerant to the casing and maintaining therein a normal liquid level at such a distance below the top opening of the said receptacle that when lubricant in the casingis lifted by ebullition from the body of liquid therein it will fall into the said receptacle separate from the liquid refrigerant in the evaporator.

7. In refrigerating apparatus; the com' bination of an evaporator of the flooded type; a compressor having its inlet connected to the evaporator to withdraw refrigerant as therefrom; a condenser connected to recelve compressed refrigerant from the compressor and deliver the liquefied refrigerant to the evaporator; a body of refrigerant in the closed system; liquid lubricant in the closed system of lower specific gravity than the liquid refrigerant and soluble to at least some extent in the latter; means for intermittently driving the compressor; a receptacle secured in fixed position in the evaporator and having an inlet for lubricant and refrigerant gas; a discharge duct leading from the said receptacle to the suction conduit of the compressor; and means associated with the evaporator for controlling admission thereto of the liquid refrigerant and maintaining in the evaporator a normal liquid level at a distance below the said inlet of the receptacle such that the intermittent lifting of lubricant above said normal level incident to evaporation in the body of refrigerant when the compressor is intermittently started causes dis- 8; charge into the receptacle of excess lubricant without such discharge of liquid refrigerant.

8. In refrigerating apparatus, the combination of an evaporator of the flooded type; a compressor having its inlet connected to the evaporator to withdraw refrigerant gas therefrom; a condenser connected to recelve compressed refrigerant from the compressor and deliver the liquefied refrigerant to the evaporator; a body of refrigerant in the closed system; liquid lubricant in the closed system of lower specific gravity than the liquid refrigerant and soluble to at least some extent in the latter; means for intermittently driving the compressor; a receptacle secured 123 in fixed position in the evaporator and having an inletfor lubricant and refrigerant gas 0 relatively larger areas; a discharge duct leading from the said receptacle to the suction conduit of the compressor, said duct having its inlet disposed at a point relatively remote from the boundary of the said inlet of the said receptacle; and means associated with the vaporizer for controlling the admission thereto of liquid refrigerant and maintaining in 11,; the evaporator a normal liquid level at a distance below the said inlet of the receptacle such that the intermittent lifting of lubricant above said normal level incident to evaporation in the body of refrigerant when the com- 3'; pressor is intermittently started causes discharge into the receptacle of excess lubricant without such discharge of liquid refrigerant.

In testimony whereof, we hereunto aflix our signatures.

HERBERT C. KELLOGG. EDWARD M. MAY.

GERTIFIGA'IFE 0F CGRERECTWN.

Patent No. i,885,837. November i, 1932.

HERBERT C. KELLOGG ET AL.

it is hereby certified that errm appears in the printed specification of the above numbered patent requiring correction as follows: Page 8, line 103, eiaim 8, for "larger areas" read "large area; and that the said Letters Patent should he read with this correction therein that the same may eonterm to the record of the ease in the Patent Utiice.

Signed and sealed this 10th day eiianuary, A. D. 1933. f

hi i. re, (Seat) Acting Commissioner 0t Patents.