US2266107A - Centrifugal refrigerating apparatus - Google Patents

Description

Dec. 16, 1941. R. w. WATERFILL CENTRIFUGAL REFRIGERATING APPARATUS Filed Sept. so, 1938 4 Sheets-Sheet 1 Jayne.

b m 61 g 75 5.9 7

I INVENTOR gig @MJ 2 22M! ATTORN EYS Dec. 16, 1941.

R. w. WATERFlLL 2,266,107

CENTRIFUGAL REFRIGERATING APPARATUS 4 Sheets-Sheet 2 Filed Sept. 30, 1938 v INVENTOR M 5 ATTORN EYS 1941- R. w. WATERFILL 2,266,107

CENTRIFUGAL REFRIGERATING APPARATUS Filed Sept. 30, 1938 4 Shets-Sheet 3 I II II II I! ll INVENTOR ATTORNEYS Patented Dec. 16, 1941 2,266,107 CEN'I'BIFUGAL REFIQIUgERATING APPARA- Bobert W. Wateriill, Montclair, N. 1., assignor to Buensod-Stacey Air Conditioning, Incorporated, New York, N. Y., a corporation of Delaware Application September 30, 1938, Serial No. 232,580

Claims.

This invention relates to the general subject of artificial refrigeration, and in its more particular aspects to improvements in the design and construction of apparatus for practicing that art.

The principal object of the invention is to provide a centrifugal compressor unit in which the impeller or impellers of the respective stages are connected directly to the shaft of a driving motor thereby avoiding intermediate gearing, and are totally enclosed along with the motor in a single casing in such a way as to obviate the need for expensive and often troublesome shaft-sealing devices.

It is a further object of the invention to provide for the lubrication of the bearings for the motor-impeller shaft of such a unit and, since these bearings are wholly enclosed and thus inaccessible, to do this in a manner which will require outside attention only at such rare times as it may become necessary to replace the small amount of lubricant which may be lost.

Yet another object of the invention is .to control the normal frothing of the lubricating 011 within the unit which results from the release of dissolved refrigerant vapors when the pressure or temperature of the oil is varied-to confine the reaction within an isolated part of the unit so that the light oil froth produced thereby may not be carried out of the lubricating system.

It is a further object of the invention to direct streams of refrigerant vapor through the impeller-motor bearings and along the shaft in opposition to any seepage of oil along that shaft beyond the bearing chambers; and to direct such vapor through the bearing chambers along with any oil froth which may be entrained thereby to v ing motor, is both flexible and economical.

In accordance with the foregoing objects, and more specifically, the invention aims to provide a two-stage centrifugal unit comprising a pair of impellers carried directly upon the opposite ends of the shaft of an electric motor and supported by the conventional bearings for that 5 shaft, a cylindrical shell serving as a support and casing both for the motor and the impeller, and a pair of scrolls or diffusers mounted in the opposite ends of the shell for cooperation with the impellers and 50 arranged that one discharges its compressed refrigerant vapor over the motor to cool it, and into the inlet of the other for further compression; and to provide a lubrication system which is also wholly enclosed within the shell of the unit and adapted to supply oil continuously to the motor-impeller shaft bearings when the unit is operating, while preventing the escape and loss of oil from its defined path..

The full nature of the invention along with other objects and various features thereof will be more fully understood from a consideration of the following description read in connection with the accompanying drawings, in which:

Figural is a side elevational view of a complete refrigerating machine, including a pair of compressor units constructed and arranged in accordance with the present invention.

Fig. 2 is an end elevational view of the assembly of Fig. 1.

Fig. 3 is a sectional view of one of the compressor units of Fig. 1 taken on the line 3-3 of that figure.

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 3.

Fig. 5 is a vertical section, on an enlarged scale, of the lubrication system of the present invention as applied to one of the bearings of the vertically disposed compressor unit of Fig. 4.

Fig. 6 is an end elevational view, partly in section, illustrating the application of the improved lubricating system to one of the bearings of a horizontally mounted compressor unit.

Fig. '7 is a sectional view, on an enlarged scale, of a part of the lubrication system of Fig. 6, and

Fig. 8 is a sectional view of a fragment of a lubrication system according to the present invention embodying another means for inducing a flow of refrigerant into the bearing chamber.

In the drawings Figs. 1 and 2 illustrate a complete refrigerating system including a cooler 8, condenser 9, and a pair of totally enclosed compressor units l0 and H constructed in accordance with the present invention and mounted directly upon the cooler and condenser, respectively. Thus the first unit I0 is bolted to the cooler in such position that the impeller l2 (Fig. 4) of its low-pressure stage l3 draws refrigerant vapor directly from the cooler and discharges it through scroll it into the casing ii of the unit and over the motor ii to cool it. The partially compressed vapor is. then intaken by the imbolted to the casing of the second unit I I.

This second unit is inverted with respect to the first one, that is, its low pressure stage i3 is located in the upper end of its casing while its high pressure one, I8, is mounted. in the lower end thereof. Accordingly, the refrigerant vapor passes from header 22 'into the low pressure stage of unit I I, and is finally discharged from its high pressure stage directly into the condenser 9.

The two units are of substantially identical design and construction. A description of one of them, ill, will accordingly sufiice. That unit is well shown in Figs. 3, 4 and 5. Referring first to Fig. 4, it will be seen that the casing I5 is preferably a cylindrical steel shell having three radially-disposed ribs 23 welded to its inner surface at spaced points which serve to support the motor It. It is particularly to be noted that the motor is bolted only to the upper ring 24 carried on the inner edge of the ribs, the lower ring 25 merely engaging the motor casing near its lower end to prevent radial movement while allowing free play to any expansion or contraction of the motor housing.

The design of the compressor stages is such that their constituent parts may be assembled in pancake fashion. Thus, and starting with the low pressure stage l3, at the bottom of the unit as shown in Fig. 4, the inner half 26 of the scroll or diffuser I4 is first fitted over the lower end the inlet guard 33 is bolted to the outer half 32 'of'the diffuser with its smoothly rounded outer surface merging with the curved inlet 34 of the impeller. The inlet guard carries a gland 35 having a grooved inner face which is now disposed in closely spaced relation to the adjacent outer surface of th reversely turned lip 36 of the impeller inlet to form a labyrinth packing adapted to prevent the short circuiting of compressed refrigerant from the outer periphery of the impeller into the inlet thereof. The assembly of the second stage of thecom pressor, I8, is substantially identical with that just described. Specifically, the inlet guard 31 is first applied to the inner half 38 of the diffuser I9, and that inner half is then bolted to the shoulder 39 of the upper flange 40 of the casing. The impeller I1 is next set in place on the upper end of the shaft, suitably keyed thereto, and fixed in position by the application of nut 4|. When properly done, the reversely'tumed lip 42 of the impeller inlet will be disposed closely adjacent the grooved gland 43 of the inlet guard 31 to form a labyrinth packing at this point adapted to prevent the short circuiting of compressed refrigerant from the outer periphery of the impeller back to its inlet. The assembly is completed by bolting the upper half 44 of the dif- The motor-impeller shaft 21 is supported in ball-bearings l6 and 41 disposed in appropriate recesses formed in the opposite ends of the motor frame. These bearings are of somewhat conventional design, and are adapted to carry both the radial and thrust loads imposed upon the shaft. It is to be noted that only the lower one, 46 (Figure 4) is positively anchored to the frame of the motor which may conveniently be done by clamping its outer race 48 between a shoulder 49 of the flange 50 defining the bearing recess, and a similar shoulder of the gland 5| which forms a labyrinth packing surrounding the shaft at 52. The upper one, 41, merely has its outer race 53 slidably disposed within the bearing recess defined by the flange 54 so that it may have a limited movement in an axial direction and thus accommodate expansion and contraction of the shaft.

The lubrication of these bearings presents several special problems. It is not sufficient merely to provide for a continuous fiow of oil to the balls. It is of equal importance to prevent the loss of oil. These problems have been solved in the present instance by providing each bearing with an oiling system of novel design, which features, among other things, a very small oil capacity such as will minimize the possible quantity of froth produced by breathing, means for confining the froth within its proper sphere, and the avoidance of an independent oil pump. Since they are both identical in principle, and substantially so in construction, a description of one will s'ufiice.

The system for the upper bearing is shown on an enlarged scale in Fig. 5. By referring to that figure it will be seen that the bearing lies wholly within a closed chamber 55, defined by the end piece 56 of the motor frame and the closure plate 51, with its slinger 58 dipping into the oil reservoir 59. Other constructional details, and their importance, will best be understood by a consideration of the operation of the system.

When the compressor unit is in operation the motor shaft 2'! drives the ball spacer ring BI] and its slinger ring 58, and the latter rotates the oil in the reservoir. This action is confined, however, to the oil in the well 6| which, it will be noted, is separated from the main body of the reservoir by the flange 52 and has access thereto only through one or more openings 63. The whirling oil is lifted, by centrifugal force, be-

tween the outwardly tapering outer surface of fuser I9 to the vanes 45 of the lower half 38. 5

force of the whirling oil reacting against these I sloping surfaces tends to drive the oil downwardly rather than upwardly. Any oil that does rise in this space, however, eventually reaches the annular groove 65 and is promptly relievedby centrifugal force through the radial openings 66 in the slinger, and passes back into the reservoir.

It is possible that some oil may get by the collecting groove 65, or may be thrown downwardly from the balls, and tend to work its way back along the surface of the shaft liner 61. Any such seepage, of course, would represent lost oil t j would not be returned to the reservoir, but could only be entrained by the refrigerant vapor and carried to some remote point in the system. If such seepage were permitted the reservoir would soon be exhausted. The replacement of oil so lost from an outside source would not represent a solution to the problem,'for that oil is lost only to the bearings. It would soon collect and clog some part of the refrigerant circuit thus interfering with continued operation. In order to prevent seepage in this way, the scroll I9 of the high pressure stage of the unit (Fig. 4) is tapped at 68, and asmall volume of the compressed refrigerant vapor is led through conduit 69 to an annular groove I in the sleeve 64 surrounding the shaft liner. The compressed vapor tends to flow in both directions from this point, some passing the adjacent labyrinth rings II and immediately rejoining the main refrigerant vapor stream in the casing I5, the remainder passing upwardly along the liner 5! and into the bearing chamber 55. It is evident that the latter flow is in direct opposition to any oil seepage along the shaft. Hence it forces any escaping oil back into the collecting groove 65 for discharge into the chamber and reservoir.

The oil in the system is at all times in contact with refrigerant vapor, and this, whether the machine is idle or in operation. This vapor, particularly when miscible with the oil, is abs'orbed therein to a greater or lesser extent, dependent upon the temperature of the oil and the pressure surrounding it. Accordingly, when the pressure is reduced, and particularly when it is suddenly reduced at the time of starting the machine, the dissolved refrigerant is released. Just as in boiling thick liquids, the release produces a large volume of light froth which is principally refrigerant vapor but, of course, contains some free oil. If it is allowed to pass directly into the main stream of refrigerant, the oil will not only be lost to the bearings, but will subsequently collect and clog some part of the refrigerant circuit. The capacity of the oil reservoir is therefore made quite small in an effort to reduce the possible volume of foam, and the liquid level therein should not be permitted to rise much above the point indicated in Fig. 5. In addition, it will be noted that the closure plate 51 flares abruptly outward from the top of the reservoir so that any froth which is generated must spread in a thin layer over a comparatively large area, thus producing a condition which is most conducive to a prompt breaking up of the froth bubbles and a settling of the oil. The relative dimensions of the reservoir and adjacent frothing space can not be stated precisely. It is preferred, however, that the average area of the space shall be at least from four to eight times that of the oil, and that the volume of the space shall be from six to ten times the capacity of the reservoir. Withthis arrangement, even though frothing occurs at more or less regular intervals, thefoam will promptly spread out and immediately start to break up as above pointed out. Some of it may, of course, find its way through the conduit; 12, along with escaping vapor, and into the settling chamber I3. There, however, it can merely break up, the vapor passing out through the open upper end ll of the chamber into the casing where it joins the main refrigerant stream, and the oil settling and returning to the reservoir through line 15. In any event, all foaming is confined either within the bearing chamber or the settling chamber where it is protected from entrainment by the main refrigerant stream.

The settling chamber (Fig. 4) is mounted on the main wall of the casing I5 with its leg 16 projecting therethrough and provided with a bulls-eye 1'! which gives a visual indication of the quantity of oil in the system. If the level is below normal, then additional oil may be supplied through conduit 18 formed in the base of the settling chamber, and, of course, that conduit may be used to drain the system should that be necessary. I

The upper end of the bearing chamber (Fig. 4) is located immediately below the inlet of the second compressor stage I8. In view of this close proximity, it is possible that some of the light oil froth may be drawn from the chamber through the bearings and opemngs 19 (Fig. 5) past the labyrinth groove 80, and along the shaft into the inlet of impeller H. In order to oppose any such flow a small volume of compressed refrigerant is directed, from conduit 59, into the annular groove 8I in the gland 82. From there the refrigerant vapor tends to flow in opposite directions along the shaft I8, a part of it immediately escaping by the labyrinth packing 80 into the main casing I5, and the remainder passing into the chamber 83, and forcing any froth therein back through passages I9 into the bearing chamber. That vapor, along with any entering the chamber from "groove III, as previously described, eventually 'finds its way through conduit I2 and the settling chamber I3, back into the casing I5 where it again joins the main stream of refrigerant.

The compressor unit heretofore described is designed for mounting in a vertical position as shown in Fig. 1. Thus, the unit of Fig. 4 is adapted to have its flange 29 bolted directly to a corresponding one on the cooler 8 with its low pressure stage I3 in direct communication with the cooler. The second compressor unit II of Fig.1 is, as has been said before, of identical construction except in so far as its compressor stages are reversed as compared with those of unit III. It is not practical, of course, merely to turn the unit of Fig. 4'end for end in mounting it upon the condenser 9 of Fig. 1 because of the character of the lubricating system. The same thing can readily be accomplished, however, by merely reversing the positions of the separate stages I3 and I9. Thus, in the unit II, the impeller I2 and scroll I4 will be assembled at the upper end of the motor shaft 21 as viewed in Fig. 4, and will be bolted to theshoulder 39 of the flange 40, while the impeller Iland scroll I9 will be assembled at the lower end of the shaft and be bolted to the shoulder of flange 29. It may then be necessary to place a shield over the open end 14 of the settling chamber 13, or to make some other provision for preventing direct impingement of the main refrigerant stream upon the oil and path in the settling chambers. Aside from the foregoing, no other changes will be necessary, and the unit may then be mounted directly upon the condenser 9 as described.

The compressor unit may readily be designed for mounting in ahorizontal position. To do so,

it is merely necessary to' make certain changes in the bearing lubrication systems, all other parts being designed and assembled in the manner and '7. In that arrangement, the bearing "a is mounted in a recess deflned by the' annular flange 81 formed as a part of the casting 88 which serves as an end of the motor frame; and lies wholly within the closed chamber 89, formed between the casting and a cap 90, the lower part of which is adapted to serve as a reservoir 9|.

Other constructional details of the system-will best be illustrated by a consideration of the manner in which it works.

When the compressor unit is in operation, the slinger ring 92 is driven by the motor shaft 210, and lifts oil from the reservoir to the sleeve 93.

The slinger ring is not positively connected to bearing races and on the balls. So much for the actual lubrication of the bearings.

The prevention of the loss of oil from the chamber presents the next problem and will now be considered. The larger proportion of any oil which is thrown out of the bearings will immediately drain along the walls of the chamber, or fall directly into the reservoir. Some of it, however, may find its way along the shaft, to the right as viewed in Fig. 7, towards the shaft opening in the casing. Before it can reach that point, however, it will be caught in the peripheral groove 95 and be thrown back along its chamfered face towards the bearing. Similarly, any oil draining along the rear wall 01 of the chamber from points above the center line of the shaft, will be caught in the groove 08, and be directed into the peripheral groove 90 in the shaft. From there, it will be thrown backwardly along the chamfered face of this groove towards the bearing so that it may eventually work its way back to the reservoir.

The lip I00 formed on the left hand end of the 'sleeve 03 will, of course, throw some oil. Most of it, however, will immediately fall into the reservoir, or on some other wall of the casing, from whence it may promptly drain back to the reservoir. In spite of the foregoing precautions some small quantity of oil may work its way along the shaft and through the openings IN and I02. Such seepage not only represents an actual loss to the bearings, but its presence in the refrigerant stream will cause trouble in the refrigerant circuit. To prevent this, a small quantity of refrigerant vapor is directed along the shaft through the openings and into the bearing chamber in direct opposition to any incipient flow 'of oil from the chamber along the shaft. Specifically, the high pressure stage is tapped, in the manner shown in Fig. 4, and compressed refrigerant is led through line 69a and the cored passages I05 and I 06 to the annular grooves I01 and I08. From there the vapor flows in both directions, a part immediately escaping by the labyrinth packings I09 and H0 back into occur, and to allow the froth to break up and settle in a normal way. The worst ,that can happen during the frothing period is for some of the foam to pass out of the chamber through conduit 72a, along with the vapor introduced as above described, to the settling chamber 13a. There, as was described in connection with Fig. 4, the oil and refrigerant will promptly separate, the vapor passing back to the casing I So, the oil returning to the reservoir through line 15a.

A pair of the horizontal units just described may be connected in series with each other and with a cooler and condenser to provide a com- =.p1ete system. Thus, if desired, one unit may be mounted upon the cooler, and another upon the condenser with appropriate connections thereto, much in the manner illustratedin Fig. 1. In another, and preferable arrangement, a pair of units may be disposed in end to endrelation with their adjacent flanges bolted together, and with their opposite ends appropriately connected to the cooler and condenser, respectively.

In the oiling systems of both the vertically and the horizontally mounted units (Figs. 5 and '7) provision is made for inducing a flow of refrigerant vapor along the motor shaft into the bearing chamber in opposition to any outward seepage of oil along that shaft away from that chamber. The purpose, of course, is to force creeping oil back into the chamberto prevent its loss through the shaft openings. In both instances it is effected by vapor taken from a tap on the high pressure stage and discharged into annular channels surrounding the shaft at the points at which it passes through the walls of the bearing chambers.

Another way of inducing this flow is illustrated in Fig. 8. There the shaft 21b carries a small impeller H5 disposed in closely spaced relation to the adjacent wall IIIi of the bearing chamber. This impeller is nothing more than a disc which serves, when rotated with the shaft, to draw vapor from the casing I5 (Fig. 4) of the unit through the shaft opening II! and to discharge it within the chamber from whence it may be released through a settling chamber such as I3, 13a (Figs. 4 and 6) in the manner hereinbefore described. In the preferred embodiment the impeller is disposed in a recess H8 in the wall of the casing so that any oil draining along the wall from above may not be caught by the impeller but may flow back into the bearing 41b or the base of the chamber in a normal fashion. As a further precaution the face of the shaft opening II! is channeled at M9 to catch any oil which may creep by the impeller and to return such oil through the drilled passageway I20 to the base of the chamber The foregoing arrangement has been shown applied only to one of the shaft openings in the bearing chamber. That is all that is believed to be necessary to illustrate the idea involved. It will be readily evident to those skilled in the art that a similar impeller may be attached to the shaft on the opposite side of bearing 41b adjacent the opposite wall of the chamber to induce a flow of vapor inwardly through the other shaft opening. It will further be noted vided to accommodate any frothing which may 7 that this arrangement has been shown in connection with a lubrication system designed for use in a horizontally disposed unit such as has been particularly described in connection with Figs. 6 and 7. It is perfectly evident, however, that it can readily be adapted to use in a verto the reservoir.

tically arranged system such as is 1 shown in Fig. 5.

The centrifugal compressor operates most efficiently with refrigerants of the so-called "low pressure" class, and the ones here shown and described are particularly designed for such service. With many of them the entire refrigerating cycle is carried out at sub-atmospheric pressure. When a refrigerant of this group is used it is entirely possible to add oil to the lubricating system, while the unit is in operation, or at any time when it is under a vacuum. The procedure in such case is quite simple, involving nothing more than the filling of the oil cup Ill (Fig. 6) and the opening of the valve H2. Atmospheric pressure then forces the oil through conduit 18a into the settling chamber and thence It will be noted that no pump or other accessories are necessary. It is important, however, not to allow the cup III to be entirely emptied during this process. If it is, then the entire system will promptly fill with air, thus requiring a purging operation before the unit can again be operated.

It will be apparent from the foregoing that all moving parts of the compressor unit, whether it be designed for vertical or horizontal mounting, to wit, the motor, the oiling systems and the impellers, are wholly enclosed within the Single casing l5. There are no relatively moving parts projecting beyond the diffusers. There is, accordingly, no need for the provision of expensive and often troublesome shaft-sealing devices. In addition it is to be noted that no men tion has been made of gaskets between the inner and outer halves of the' diffusers, nor'between the diffusers and the flanges to' which they are bolted, and, as a general rulefnone will be required. Any leakage of refrigerant vapor will be of infinitesimally small proportion; and the leakage, in any event, will only be between one part of the system and another, not from the system to the surrounding atmosphere. A further feature of importance is the fact that the impellers are mounted directly upon the opposite ends of the motor shaft, thereby doing away with intermediate gearing. In this connection it will be noted that the motor itself lies between the two compressor stages, and is cooled by the stream of partially compressed gas discharged from the first stage. The temperature of the motor may accordingly be kept at a considerably lower point than would otherwise be possible.

Since certain changes may be made in the embodiment of the invention and in the design, construction and arrangement of the various constituent parts, it is intended that the foregoing shall be construed in a descriptive rather than in alimiting sense.

What I claim is:

1. In a motor driven compressor unit a lubrication system for a shaft bearing comprising a chamber surrounding the bearing and having openings therein through which the shaft passes with a running fit and having its lower portion adapted to serve as an oil reservoir, a slinger driven by the shaft for supplying oil from the reservoir portion to the bearing, means for causing a flow of small volume of the gas being handled by the compressor through the shaft openings and along the shaft into said chamber to prevent seepage of oil along the shaft away from said chamber, and means for separating the gas from anyoil which it may have entrained in passing through said bearing chamber, said last mentioned means comprising a settling chamber having communication with the inlet of said compressor, a conduit connecting the upper portion of the bearing chamber with said settling chamber, and a second conduit connecting the lower portion of said settling chamber with the oil reservoir portion of said bearing chamber.

2. In a motor driven compressor unit having a shaft bearing mounted within the casing of the unit in the path of vapor, a lubrication system for such shaft bearing comprising a chamber surrounding the bearing and having openings therein through which the shaft passes with a running fit, an oil reservoir formed in the base of the chamber below the bearing, means for lifting oil from the reservoir to the bearing, means for causing a flow of a small volume of refrigerant vapor through the shaft openings and along the shaft into the chamber to prevent seepage of oil along the shaft away from the chamber, a settling chamber comprising a tubular shell having an open upper end located substantially on a level with the top of the bearing chamber and a closed lower end disposed substantially on a level with the base of the reservoir portion of the bearing chamber, a conduit connecting the upper portion of the bearing chamber with the settling chamber, and a second conduit connecting the bottom of the settling chamber with the base of the reservoir for returning oil to the bearing chamber.

' 3. In a totally enclosed motor driven vapor compressor unit including a shaft bearing mounted within the casing of the unit in the path of vapor, a lubrication system for such shaft bearing comprising a chamber surrounding the bearing and havingv openings therein through which the shaft passes with a running fit and having its lower portion adapted to serve as an oil' reservoir, a slinger driven by the shaft for lifting oil from the reservoir to said bearing, and

means connecting said chamber with the inlet of the compressor whereby to induce a flow of vapor through the shaft openings into said chamber, the volume of said chamber being on the order of a multiple of the volume of its reservoir portion, and the cross-sectional area of said chamber at a point above the normal oil level in its reservoir portion and below the bearing being on the order of a multiple of the crosssectional area of said reservoir portion at the normal oil level, whereby any froth generated by the release of vapor from the oil in the reservoir may rise in the chamber and spread over a large area to facilitate its breaking up.

4. In a totally enclosed motor driven vapor compressor unit, a lubrication system according to claim 3, further characterized by the provision of a settling chamber comprising a tubular shell mounted within the casing of the unit with its upper end communicating with the inlet of the compressor and with its closed lower end disposed substantially on a level with the bottom of the reservoir portion of said bearing chamber, a conduit connecting the upper portion of said bearing chamber with said settling chamber for conveying oil froth and refrigerant vapor to said settling chamber, and another conduit connecting the bottom of said settling chamber with the bottom of the reservoir portion of said bearing chamber for returning oil from the settling chamber to the reservoir.

5. In a totally enclosed motor driven compressor unit, a lubrication system, according to claim 3, further characterized by the provision of a settling chamber comprising an L-shaped tubular shell having its vertical leg mounted on the wall of the casing of the unit with its upper and communicating with the inlet of the compressor and its horizontal leg projecting through the wall of the casing substantially on a-level with the base of said reservoir portion of said bearing chamber, a transparent member closing the end of the horizontal leg of said settling chamber, a conduit connecting the upper end of said bearing chamber with the upper portion of said settling chamber for conveying oil froth and refrigerant vapor to said settling chamber and another conduit connecting the bottom of said settling chamber with the base of said reservoir portion of said bearing chamber for returning oil to said reservoir.

6. In a totally enclosed motor driven compressor unit, a lubrication system according to claim 3, further characterized by the provision of a settling chamber comprising an L-shaped tubular shell having its vertical leg mounted on the wall of the casing of the unit with its upper end communicating with the inlet of the compressor and its horizontal leg projecting through the wall of the casing substantially on a level with the base of said reservoir portion of said bearing chamber, a transparent member closing the end of the horizontal leg of said settling chamber, a conduit leading from the bottom of the settling chamber to a point outside of the casing of the unit through which oil may be supplied to or removed from the lubricating system, a conduit connecting the upper end of said bearing chamber with the upper portion of said settling chamber for conveying oil froth and refrigerant vapor to said settling chamber and another conduit connecting the bottom of said settling chamber with the base of said reservoir portion of said bearing chamber for returning oil to said reservoir.

7. In a motor driven compressor unit, a lubrication system, according 'to claim 2, further characterized in that the settling chamber has a horizontal leg at its lower end which is adapted to project through the casing of the unit, a transparent membrane closing the end of such horizontal leg, and a conduit also adapted to pass through the casing of theunit to provide for the filling or draining of the lubrication system. I

8. In a refrigerant compressor unit in which the compressor, its driving motor, and a shaft bearing are wholly enclosed in a substantially leak-tight casing, a lubrication system for such shaft bearing comprising a chamber surrounding the bearing with openings therein through which the shaft passes with a running fit, said chamber having its base portion adapted to serve as an oil reservoir for the system, a slinger driven by the shaft for lifting oil from the base of said chamber to the bearing, means connecting said chamber with the compressor to cause a fiow of refrigerant vapor through the shaft openings and along the shaft into said chamber to prevent seepage of oil along the shaft away from the chamber, means for separating refrigerant vapor from the oil to permit the vapor to return to the compressor, and means for returning the separated oil to the reservoir portion along the shaft into said chamber to oppose any fiow of oil along the shaft awayfrom said chamber, means for separating the vapor from the oil whereby the vapor may return to the compressor and means for returning the separated oil' to the reservoir portion of said chamber;

10. In a motor driven vapor compressor unit having a shaft bearing mounted within the unit and lying in the path of vapor, a lubrication system for the shaft bearing comprising a closed chamber surrounding the bearing with openings therein through which the shaft passes with a running fit, an oil reservoir formed in the base of said chamber beneath the bearing, means for lifting oil from the reservoir to the bearing, means for directing a small volume of compressed vapor from the outlet side of the compressor through the shaft openings and along the shaft into said chamber in opposition to any seepage of oil along the shaft away from said chamber, a settling chamber, a conduit for conveying refrigerant vapor and oil froth from the upper portion of said bearing chamber to said settling chamber, said settling chamber having its upper portion in communication with the inlet of the compressor whereby refrigerant vapor may be returned to the compressor, and a conduit adapted to convey oil from the base of said settling chamher to said reservoir portion of said bearing chamber.

ROBERT W. WA'IERFILL.

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