Refrigerant compressor

A refrigeration compressor is disclosed which incorporates an improved lubrication system to insure adequate lubrication to all bearings via a single elongated axial offset passage provided in the crankshaft. The lubrication system also incorporates a passage arrangement which serves to vent any refrigerant gases which may be encountered as well as to prevent priming of the vent passage which could result in transfer of lubricant into the motor compartment.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates generally to refrigeration compressors and 
more particularly to lubrication systems for hermetic refrigeration 
compressors. 
Refrigeration compressors and more specifically refrigeration compressors 
of the hermetically sealed reciprocating piston type normally provide a 
reservoir of lubricating oil in the lower portion or sump of the sealed 
shell. Pumping means are normally provided which operate to circulate oil 
to the bearings through passages provided in the crankshaft. Because the 
oil is in open communication with the refrigerant, it is not uncommon for 
some of the refrigerant in liquid and gaseous form to become mixed in the 
oil. As the oil is heated during operation of the compressor, portions of 
this liquid refrigerant will be boiled off. It is therefore important that 
the crankshaft lubrication passages incorporate venting means to avoid 
vapor lock which could block the flow of lubricant to the bearings. It is 
also generally desirable to minimize the amount of intermixing of the oil 
and suction gas flowing to the compressor to both prevent slugging of the 
compressor as well as the carry over of oil into the refrigeration system. 
Accordingly, the present invention provides an improved lubrication system 
which incorporates passages to effectively vent any gaseous refrigerant 
therefrom yet still assure that no oil is carried over into the primary 
suction gas flow area. The system is economical to manufacture yet also 
assures full and complete lubrication of all bearing surfaces over a wide 
range of operating conditions while also minimizing the potential for 
mixing of the oil with the suction gas flowing to the compression 
cylinders. 
Additional advantages and features of the present invention will become 
apparent from the subsequent description and the appended claims taken in 
conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings and more specifically to FIG. 1, there is 
shown a refrigeration compressor 10 of the hermetic reciprocating piston 
type. Compressor 10 includes a compressor housing 12 supported within 
outer shell 14 and including a pair of compression cylinders 16 and 18 
within which pistons 20 and 22 are respectively reciprocatingly disposed. 
An electric motor 24 is operative to reciprocatingly drive pistons 20 and 
22 and includes a stator 26 secured to compressor housing 12 and a rotor 
28. Rotor 28 is secured to and operative to drive crankshaft 30 which is 
rotatably journaled in upper and lower bearings 32 and 34. 
As shown, the upper end of motor 24 is enclosed by a shroud 56 secured to 
stator 26. An inlet opening 58 is also provided in outer shell 14 in 
aligned relationship to a suction inlet opening 60 provided in motor 
shroud 56. A suction coupling 62 carried by shroud 56 includes a 
telescopically movable portion which is biased into engagement with the 
inner surface of shell 14 so as to direct substantially all suction gas 
entering shell 14 into the thus defined motor chamber. A suction outlet 
conduit 64 is fitted within another opening 66 provided in shroud 56, 
opening 66 being positioned in circumferentially spaced relationship to 
suction inlet opening 60. Suction outlet conduit 64 operates to conduct 
suction gas across the end turns of motor stator 26 and deliver same to 
respective cylinders 20, 22 for compression. 
As best seen with reference to FIGS. 2 and 3, crankshaft 30 incorporates a 
centrifugal oil pumping means in the form of a relatively large diameter 
axially inwardly extending bore 36 positioned in coaxial relationship to 
the axis of rotation thereof and opening outwardly from lower end thereof. 
Bore 36 is in open communication with the oil sump 38 in the bottom of 
shell 14 via passage 40 in the lower bearing housing. An elongated axially 
extending main oil feed passage 42 is positioned in radial offset 
relationship to the axis of rotation of crankshaft 30 and in intersecting 
relationship to bore 36. A relatively short bore 44 extends radially 
outwardly from passage 42 and serves to provide lubricant flow to upper 
bearing 32 and a second passage 45 extends radially outwardly from bore 36 
to provide lubricant flow to lower bearing 34. Additional passages (not 
shown) are provided to supply lubricant flow to each of the respective 
piston rod bearings. 
In order to avoid the accumulation of trapped vapor within passage 42 which 
could possibly prevent adequate lubrication flow, a first vent passage 46 
is provided extending in a radial direction across the axis of rotation 47 
of crankshaft 30 from the upper end of passage 42 and opens outwardly 
through the outer surface of crankshaft 30 in an area underlying rotor 28. 
A pair of chevron grooves 48, 50 are provided in the outer surface of 
crankshaft 30 and extend axially upwardly in oppositely spiralling 
directions from passage 44 so as to allow any gases within passage 42 to 
vent above the motor. 
Under certain high temperature operating conditions the amount of gas 
within the refrigerant may increase substantially to the point where it is 
desirable to provide multiple vents for passage 42 to insure adequate 
lubricant flow therethrough. Additionally, at low operating temperatures 
such as at startup, there may be a substantial amount cf liquid 
refrigerant in the oil which will be boiled off as the oil warms thus also 
increasing the volume of gas within passage 42. Accordingly, a second vent 
passage 52 is also provided in crankshaft 30 also extending radially 
across the axis of rotation 47 and opening outwardly therefrom at a 
location below the upper bearing 32. This vent passage will not only 
operate as an additional gas vent for refrigerant vapors within passage 42 
but also serves as a siphon break vent in the event the upper vent 46 
should inadvertently become primed and commence pumping of oil. Such a 
situation could occur in the event the pressure differential between the 
oil sump and the area enclosed within the motor cover becomes sufficiently 
great to draw oil from passage 42 across the axis of rotation of the 
crankshaft through passage 46. Once passage 46 becomes filled with oil up 
to the axis of rotation, priming will be complete and from that point on 
passage 46 will act as a centrifugal pump. However, in the present 
invention, should passage 46 become primed and begin to pump, the 
reduction in pressure within passage 42 will result in gas being drawn in 
through passage 52 and up passage 42 to break the primed condition 
existing in passage 46. This will occur without significant interruption 
in flow of lubrication to upper bearing 32 as the greater mass of the 
lubricating oil versus the refrigerant gas combined with the centrifugal 
force due to rotation of the crankshaft will cause a radially inner and 
outer stratification between the two fluids. That is, the gas being 
lighter will flow along the radially inner surfaces of passage 42 while 
oil will be thrown to the cuter portion thereof. Thus, the provision of 
passage 52 serves to limit the potential for oil to be pumped into the 
suction gas flow path within the motor area and hence reduces the 
potential mixing and carry over thereof into the refrigeration system. It 
should be noted that there also exists the possibility of passage 52 being 
primed in the same manner described above with respect to passage 46. 
While this can occur, it does not give rise to the same concerns noted 
above because passage 52 opens into the crankcase which in turn is in open 
communication with the oil sump. Hence, any oil pumped out through passage 
52 will be returned to the sump and does not pose the same potential 
problem with respect to intermixing with the suction gas. 
Referring now to FIG. 4, a portion of crankshaft 30' is shown wherein 
corresponding portions thereof are indicated by like numbers primed and 
which incorporates an alternative arrangement for forming the passage 44 
of crankshaft 30. In this embodiment, passage 44' is formed by drilling 
diametrically through crankshaft 30' from the same side of the crankshaft 
that passages 46, 52 and 45 open outwardly. There is no need to plug the 
longer portion of passage 44'. This procedure enables all of the radially 
extending passages to be formed from one side of the crankshaft thereby 
eliminating the need to reposition the crankshaft for two separate 
drilling operations. 
While it will be apparent that the preferred embodiments of the invention 
disclosed are well calculated to provide the advantages and features 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.