US2898072A - Lubricating system for refrigerant compressors - Google Patents

Description

9 o. H. BUSCHMANN 2,898,072

LUBRICATING SYSTEM FOR REFRIGERANT COMPRESSORS Filed Feb. 23, 1954 4; 212.1. 24 //1 Ma y;

I INVENTOR.

OsXar #ZzzscZrzzzx/X I BY United States Patent O LUBRICATING SYSTEM FOR REFRIGERANT COMPRESSORS skar H. Buschmaun, Sidney, Ohio, assignor to Copeland Refrigeration Corporation, Sidney, Ohio, a corporation of Michigan Application February 23, 1954, Serial No. 411,683 6 Claims. (Cl. 230-206) The present invention relates to refrigeration compressors and more particularly to an improved lubricating system and arrangement for refrigeration compressors of the hermetic type.

A common hermetic type of refrigeration motor-compressor unit comprises an upright coaxial direct-drive unit having an overhead electric driving motor, an integral motor-compressor shaft, and a reciprocating compres- $61 with horizontal pistons driven by throws on the shaft, the entire unit being enclosed in a sealed casing with lubricating oil for the moving elements contained in the lower portion of the casing. My improved lubricating system will be described in a preferred embodiment in conjunction witha sealed unit of the indicated variety, although it will be understood that the specific features of the motorand compressor components per se form no part of my present invention and are subject to variation. In the past, various methods and systems have been employed to circulate the oil to the parts of such a unit requiring lubrication. A common arrangement utilizes a fluid pump positioned adjacent the lower end of the shaft for forcing the oil upwardly through suitable passages. It has heretofore been usual to provide lubricating pumps of the positive displacement type because of the fact that although pumps of the centrifugal type are simpler, cheaper and less subject to deterioration due to wear, they have been subject to vapor lock, due to the peculiar conditions, obtaining in such refrigerant compressor applications. Vaporization of entrained refrigerant has also reduced the efiiciency of systems incorporating positive displacement pumps. As is well known, refrigerant circulated in such refrigeration systems unavoidably becomes entrained with the oil. When the mixture; er oil' and refrigerant enters the pump and oil passages, where it is agitated and its temperature is raised, the refrigerant expands and tends to block the pumpIand lubricating system, causing partial or even posed spider section 30 having amain bearing boss 32 total failure of lubrication. Consequently, the bearing surfaces are inadequately lubricated and subject to. ex

cessive and prematurewean It is therefore one object oflthje presentiinvention to,

provide an improved lubricating system for awhermetic compressor which eliminates the difliculties heretofore encountered by providing means to eliminate any tendency of the refrigerant to collect and create vapor lock in the fluid pump of such compressors.-

Another object of the present invention is the promoving'components of la compressor' unit'fby"providing positive lubricating action and in 'which the volatile 'refrigerant .mixed with the lubricating 'oil is substantially ing operationl V p j j y g A further object of the present invention is the proyisionfof a compresserlubrieating system by which all proving components of the compressor are-adequately eliminated from the main oil pass'ages diiring the puinpl,

2,898,072 Patented Aug. 4, 1959 and instantaneously lubricated upon initial starting of the compressor.

Still another object of the present invention is the provision of rotary vent means for ejecting lubricating oil and providing positive escape means for the volatile refrigerant from the vicinity of the fluid pump.

A still further object of the present invention is the provision of an improved arrangement for effectively These and other objects and advantages of the in-' vention will become apparent to those skilled in the art upon consideration of the present disclosure in its entirety.

In the accompanying sheet of drawing in which:

. Figure l is a vertical, cross-sectional view taken through a refrigeration compressor incorporating the invention and showing some parts of the unit in section and others in elevation;

Fig. 2 is an enlarged cross-sectional view taken on the lines 2-2 and looking in the direction of the arrows; an

Fig. 3 is an enlarged cross-sectional view taken on the line 33 and looking in the direction of the arrows.

Referring now to the drawings wherein like reference characters designate like or corresponding parts through. out the several views, there is shown in Figure 1 a refrigeration compressor assembly 10 embodying features of the present invention. The compressor assemblyis illustratedin its normal upstanding; position and comprises an overhead electric motor 12, a shaft 14 and a' flange 25 and 26, respectively, which are joined togetherby welding or the like to form an hermetically sealed, unitary casing forthe operating mechanism. I The casting 16, which supports the entire operating mechanism, comprises a unitary member having an upper annular mounting frame 28, a horizontally discentrally positioned thereon, a depending cylinder block portion 34 and a lower bearing wall 36. This structure,

'whichforms the foundation for the compressor unit is substantially conventional and is subject to variation without departing from the present invention. The mounting frame 28 is fitted within the upper shell portion 20 of the casing and secured thereto by suitable means. Preferably, the extreme upper endof the annular flange is separated from the inner walls of the upper shell portion 22 by a nonresonant, flexible material 38'whicl1 serves to absorb vibrations generated in the unit and also reduce noise transmission through the casing 18.

The overhead electric motor 12 of the assembly includes a conventional stator assembly 40 and armature V I Eli, assembly 46, the latter fa'stupon shaft portion 58 which Vision of an improved arrangement forlubricat ngjthe may, as'shown, constitute an integral coaxial extension of the compressor eccentric shaft portion 19. Weights 48 and; 50 suitably arranged on the upper and lower portions -of the armature are provided to counterbalance theeccentric shaft and driven components.

Shaft 14 is vertically disposed in the unit centrally of the casing and the upperreduced shaft portion 58 is fast in the armature 46 andkeyed thereto-at its extreme upper end by "an interengaging lock member 60.

shown at 66 and 6'8, and each is equipped with a piston."

70 and 72, respectively. The pistons 70' and 72 are connected as by wrist pins (not shown) and connecting rods 78 and 80 to eccentrics- 81 and '8-2' respectively, formed on the shaft 14'. The outer ends. of the cylinders are closed byavalve plate 741 and a cylinder head. 76, which areconventi'onallyprovided with passage and valve means (not shown) and control the flow: of refrigerant passing to and from the cylinder during" the compression cycle.

The central portion 44- of the shaft 14 is rotatably journaled; in the main bearing boss 32 while the lower end of;the crankshaft is rotatably j'ournaled in thebearing wall 36 formed integrally with the casting 16 and vertically supported in the bearings 32' and 36- by a thrust bearing plate 96 suitably secured to the lower side of bearing wall 36. Bearing liner 90 boss 32 does not extend all the way to the top of the boss, and an additional bearing and lubricant retaining ring 88 is mountedin boss 32* and spacedabove the upper end of bearing 90 to provide an annular lubricating oil passage 92 therebetween as will hereinafter be described. A- bearing liner 94- is also inserted in the lower bearing 36.

The refrigeration compressor, as described thus far, is mostly conventional and will operate uponenergizafor a limited distancein the end of the shaft in anyevent. As will hereinafter be described, bore 110 provides a cavity in which refrigerant vapors escaping from the lubricating oil tend to collect.

Bearing liner sleeve 94, seated in the bearing wall 36, as best seen in Fig. 1, terminates at a point slightly above: the; slots 100- and defines the upper limit of an 7 annular oil outlet passage 112 located within the bear ing wall 36 and above plate 96, which extends outwardly to close the outletpassage, 112 and the lower face of the bearing. Passage 112, which is formed adjacent the lower end of the shaft 14, is in continuous communication withtheouter ends. of theradial slots 100 and serves to conduct oil to. an outlet port 114 in the bearing wall 36. The outlet port 114 is formed on an angle to the shaft axis and extends upwardly from the annular passage 112, through alower cut-away portion of the bearing 94-, to a duct port formed on the outer periphery of tion of the motor 12 to rotatabl-y drive the shaft 14 and operate the compressor to circulate refrigerant in the conventional manner;

The lubricating system includes an oil reservoir 98' in the bottom ofthe casing: As indicated heretofore, the bottom wall 24' of the shell 22 has upwardly inclined portions defining a depressed center portion, in the deepest' part of which the bearing wal13'6 is accommodated. Preferably, the oil is of sufficient depth in the casing, as indicated in Fig. 1, to almost but not entirely cover the bearing wall 36;

Lubricating oil is supplied from the reservoir 98 to the moving elements by a centrifugal fluid pump, the rotor of'whiclr is formed by; the enlarged lower end portion 17' of the shaft 14: which isjournaled in the bearing 36; lower end of the rotor portion 17 of the shaft is'formed with a plurality ofangularly' spaced, radial pumping slots 10(l'extending from the center of the shaft to its periphery. The bottoms of the slots are closed by the. thrust bearing'pl'ate 96, as best shown in Fig; 2. In the preferred construction shown, four slots are formed in the" shaft. It' is obvious however, that the number of slots maybe varied in accordance with the desired flow andpressure of the pumped oil; The integral segmental metal. portions 102 of' the lower shaft end, which are defined as the area between the slots 100, rest on the thrust bearingpl'ate 96 secured to the; thrust bearing 36 t'o'provide a vertically supporting bearing for the shaft. It will be apparent that these oil pumping passages may be: formed whollyin the shaft 14 by drilling radially extending, angularly spaced holes or bores in the shaft and in which case the closing function of the thrust bearing plate may be omitted.

'An. oil inlet aperture or port 106. is formed centrally of the. thrust. bearingplate 96 and provides access for the. oil passing from the reservoir 98. to the oil pump. Preferably, portis covered with a. filter screen 108. suitably secured on the lower-surface of the bearing plied e; 961w a securing flange 9.7. Axially-in thelowcriend por-- tion. 17 of. the. shaft and communicating with. the inlet. port 106 and the slots 100; is an inlet. hole 110-open atthe lower end of the shaft and extending upwardly a limited distance above the slots.- It isto be noted: that in the initial construction of the-shaft,.,it is usually con-1 venient if not apractical necessity, where conventional checking practices are followed, to form an axial hole the thrust bearing 36. Suitably connected to the duct port on the outer end of the passage 114 is an oil riser tube 116. Tube 116, which is bent outwardly to clear the eccentric straps, terminates at its upper end in an inlet feed port of a bearing feed passage 118 formed in the main bearing boss 32. Passage 118 is suitably connected to the tube 116 at one end and extends upwardly and inwardly to the annular passage 92.

The basic operation of the pump is conventional and will be. readily understood: Radial movement of oil forced lay-rotation of-the pumping slots creates a partial vacuum within the center bore 110 centrally of the slots. To fill this vacuum, the pressure in the casing forces oil through screen 108-, inlet port 106 and into the center bore 110 such that oil is continually flowing into the center hole during operation of the pump. Meanwhile, the oil forced outwardly from the slots 100 enters oil passage 112. whereby the bearing li'ner 94 is lubricated. Since the passage 112 is substantially closed by the coacting bearing and shaft elements, oil pressure quickly builds up in the passage and the oil is forced through the outlet passage 114, upwardly through the supply duct 116 and passages 118, 92, as previously stated. Oil which seeps between'the bearing surfaces 44-90 for lubrication at this point flows downwardly around the bearing 90, onto the shelf 84', and down to the eccentrics 81 and 82, while additional lubrication is provided by oil thrown from the vent port 125,. presently to be described, and in addition, when the shaft is rotating, some of the oil is thrown outwardly by centrifugal action to lubricate the pistons 70. and 72 and wrist pins.

. To prevent vaporized refrigerant from affecting the flow of-fluidin the lubricating system, and the efficiency of the pump, a rotary vent 125 is formed in the shaft 14 and extends angularly upwardly and outwardly from the center bore 110 to an outer discharge or jet port formed on the periphery of the shaft 14 at a point above the level of g the oil reservoir. As shown, the jet port is formed in a horlzontal upper surface portion 126 of the pumping rotor portion 17 of the shaft and lies in a vertical plane diametrically opposite the line of maximum throw of eccentric. 82. Thus. the jet hole points toward the axis ofcylinder 68 when piston 72 is at bottom dead center, and. the hole 125. is also so inclined as to discharge into the interior of the piston. and assist in lubricating the. wrist pin at. such time. Hole 125 also sprays oil around the interior of the compressor section, providing both. an oil fog and. effective splash lubrication. Hole 125 further permits. vaporousv refrigerant to escape from the center hole 110. and relieves such pressure as may be exerted by the refrigerant, in the vicinity of the fluid pump. A natural centrifugal separating action takes place at the hole 110, inasmuch as the. oil being the heavier component, is thrown outwardly through the pumping slots and the lighter refrigerant is forced inwardly and rises through holes 110, 125. The radial component'of hole 125 develops a positive pumping action on the fluid 5 Within the hole 110 and thereby prevents the forces exe'rted by the pumping passages, defined by the slots 100, from sucking vapor back through the vent and into the center hole 110. Preferably, the rotary vent is given a sufl'icient radial slope so that it exerts enough radial force to also pump a certain quantity of oil for splash lubrication of the lower portions of the compressor, as indicated above. The oil thrown from the jet port also provides instantaneous lubrication when the compressor starts without the usual delay for the oil to flow through the delivery passages from the pump outlet. Vent 125 also prevents gaseous refrigerant from collecting in and blocking the pumpiduring oif cycles, so that when the compressor is started, the oil begins to flow immediately.

It will be apparent from the foregoing that an improved lubricating system has been provided for refrigeration compressors of the hermetic type and wherein a full flow of lubricating oil is instantaneously and continuously provided for properly and adequately lubricating the moving elements of the motor compressor unit.

While it is apparent that the preferred embodiment of the invention herein disclosed is well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

I claim:

1. In a lubricant pumping and refrigerant separating mechanism for a refrigerant compressor of the type having a substantially sealed case wherein liquid normally stands at a level and wherein a gaseous atmosphere occupies the space above such level, a pump rotor rotatable in said case upon a substantially vertical axis and having a vertically extending inlet portion having a submerged mouth located substantially on said axis, and having centrifugal impeller portions communicating with and extending radially outwardly from said inlet portion, a pump housing portion surrounding said impeller portions and having an outlet through which liquid may be delivered to a desired destination, means for separating lighter constituents from the liquid, comprising a vent-defining passage portion extending both upwardly and radially and rotatable coaxially of said rotor and communicating at its lower end directly with said inlet portion at a position above the inner end of said impeller portions and at the other end having a substantially unobstructed discharge opening above said level.

2. A mechanism as defined in claim 1 wherein the radial extent of said vent-defining passage portion is less than the effective radial length of said impeller portions.

3. In a lubricant pumping and refrigerant separating mechanism for a refrigerant compressor of the type having a substantially sealed case wherein lubricating liquid normally stands at a level, and wherein an atmosphere formed primarily of gaseous refrigerant occupies the space above such level, a pump rotor rotatable in said case upon a substantially vertical axis and having a vertically extending and substantially axial inlet portion having a mouth submerged in the liquid and located substantially on said axis, submerged centrifugal impeller portions communicating with and extending radially outwardly from a lower portion of said inlet portion, a stationary pump casing portion surrounding said impeller portions and having an outlet, means for conducting liquid from said outlet to a desired destination, means for separating lighter constituents from the liquid, comprising a vent-defining passage portion extending both upwardly and radially and rotatable coaxially of said rotor and communicating at its lower end directly with said inlet portion at a position above said impeller portions and appurtenant to the upper end of said inlet portion and at the other end having asubstantially unobstructed discharge opening into said atmosphere above said level, the effective pumping capacity of the impeller portions being insufiicient to prevent some of the oil from being portion.

4..In a lubricant pumping and refrigerant separating mechanism for a refrigerant compressor of the type having a substantially sealed case wherein lubricating liquid normally stands at a level, and wherein an atmosphere formed primarily of gaseous refrigerant occupies the space above such level, a refrigerant compressor shaft rotatable in said case upon a substantially vertical axis,- oil pumping and refrigerant separating means appurtenant to and rotatable with the lower end of said shaft, including a vertically extendingand substantially axial inlet portion having a mouth submerged in .the liquid and located substantially on said axis, and having submerged centrifugal impeller portions communicating with and extending radially outwardly from a lower portion of said inlet portion, a stationary pump casing portion surrounding said impeller portions and having an outlet, means for conducting liquid from said outlet to a desired destination, means for separating lighter constituents from the liquid, comprising a vent-defining passage portion extending both upwardly andradially and rotatable coaxially of said rotor and communicating at its lower end directly with said inlet portion at a position above said impeller portions and appurtenant to the upper end of said inlet portion and at the other end having a substantially unobstructed discharge opening into said atmosphere above said level, the effective pumping capacity of the impeller portions being insuflicient to prevent some of the oil from being pumped through and discharged from said passage portion.

5. In a lubricant pumping and refrigerant separating mechanism for a refrigerant compressor of the type having a substantially sealed case wherein lubricating liquid normally stands at a level, and wherein an atmosphere formed primarily of gaseous refrigerant occupies the space above such level, a refrigerant compressor shaft rotatable in said case upon a substantially vertical axis, oil pumping and refrigerant separating means appurtenant to and rotatable with the lower end of said shaft, including a vertically extending inlet portion having a mouth submerged in the liquid and located substantially on said axis, and having submerged radial slots formed in the lower end of said shaft and defining centrifugal impeller portions communicating with and extending radially outwardly from a lower portion of said inlet portion, a stationary pump casing portion surrounding said impeller portions and having an outlet, means for conducting liquid from said outlet to a desired destination, means for separating lighter constituents from the liquid, comprising a vent-defining passage portion extending both upwardly and radially and rotatable coaxially of said rotor and communicating at its lower end directly with said inlet portion .at a position above the inner end of said impeller portions and at the other end having a substantially unobstructed discharge opening above said level.

6. In a lubricant pumping and refrigerant separating mechanism for a refrigerant compressor of the type having a substantially sealed case wherein lubricating liquid normally stands at a level, and wherein an atmosphere formed primarily of gaseous refrigerant occupies the space above such level, a refrigerant compressor shaft rotatable in said case upon a substantially vertical axis, refrigerant compressing mechanism drivable by said shaft and located above said level in said case, oil pumping and refrigerant separating means appurtenant to and rotatable with the'lower end of said shaft, including a vertically extending inlet portionrhaving a mouth submerged in the liquid and located substantially on said axis, submerged centrifugal impeller portions communicating with and extending radially outwardly from said inlet portion, a stationary pump casing portion surrounding said impeller portions and having an outlet, means for conducting liquid from said outlet to a desired destination, means for separating fighter constituents fromthe liquid,

upwardly and radially and rotatable. coaxially of said rotor and, communicating at, its lower end directly. with said inlet portion, at. a position, above, the inner end of said.

impeller pontions and at tho other nd having a substantially unobstruoted discharge opening above said level,

said. ogening; being during at leasi a part. of its, rotation directed, toward but spaced from. said refrigerant compressingmechanism wh reby liquid may be ejectedfrom saidpassaga under. pumping effect. oi its, radial com ponent and directed against said mechanism to lubricate the same. g f

References Cited in thefileof this patent UNITED STATES PATENTS

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