US3388855A - Refrigerant compressors having vertical crankshafts - Google Patents

Description

June 18, 1968 R. w. AYLING ET AL 3,333,855

REFRIGERANT COMPRESSORS HAVING VERTICAL CRANKSHAFTS Filed Oct. 17, 1966 s FIGJ. 2

FIG.2. FIGJ. M I ll I 1 g3 3| l3 3| 32 32A T I as 25 I V 33 4 lfi ll 9 37 36 INVENTORS= ROBERT W. A'YLING, PAUL G.THAYER,

ATTORNEY United States Patent 3,388,855 REFRIGERANT COMPRESSORS HAVING VERTICAL CRANKSHAFTS Robert W. Ayling and Paul G. Thayer, Staunton, Va.,

assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 17, 1966, Ser. No. 587,295 Claims. (Cl. 230-206) ABSTRACT OF THE DISCLOSURE A refrigerant compressor has a vertical crankshaft with an off-center bore for supplying oil to bearings. The bore is connected by an oil pump passage to a central oil inlet opening in the bottom of the crankshaft. The pump passage is connected through a gas vent orifice and a gas vent passage larger than the orifice to the surface of the crankshaft which is connected by a gas outlet passage t the oil sump of the compressor.

This invention relates to refrigerant compressors having vertical crankshafts, and having oil pumping means at the bottoms of such crankshafts.

The patents of R. W. Ayling, Nos. 3,171,588 and 3,- 259,307 disclose refrigerant compressors having vertical crankshafts with vertical, off-center bores therein connecting with bearings, such bores connecting with radial bores near the bottoms of the crankshafts, such radial bores connecting through central bores in the bottoms of the crankshafts, with the oil sumps of the compressors. The radial bores act as centrifugal pumps, pumping oil from the oil sumps through the off-center bores to the bearings. Since, in such compressors, refrigerant liquid is mixed with the oil, when pressure changes and heating occur, refrigerant gas is produced which interferes with the flow of oil. The previously mentioned Patent No. 3,- 259,307 discloses how such gas can be vented at the discharge side of the oil pump.

This invention vents trapped gas at the suction side of such an oil pump. At the center of rotation where the axis of such a crankshaft crosses the radial bOre operating as an oil pump, gas bubbles are formed as the oil is centrifuged outwardly by centrifugal force, and in the usual compressor, may grow to such sizes that the entrance of oil into the radial pump bore is seriously restricted, preventing the bearings from being supplied with sufiicient oil. This invention provides in such a crankshaft, an orifice having an inlet close to the axis of the crankshaft, connecting with the inlet of the oil pump, and having an outlet connecting through an annular passage, and an opening in the surrounding bearing housing, with the oil sump. Gas bubbles formed at the pump inlet are pumped out through the orifice, preventing the growth of such bubbles in the pump inlet. The orifice permits only a relatively small amount of oil to be pumped out with the vented gas.

An object of this invention is to improve the oil pumping means of refrigerant compressors having vertical crankshafts.

Another object of this invention is to vent trapped gas at the inlet of the oil pumping means of a refrigerant compressor having a vertical crankshaft.

This invention will now be described with reference to the annexed drawings, of which:

FIG. 1 is a fragmentary sectional view of a refrigerant compressor embodying this invention;

FIG. 2 is an enlarged sectional view of the oil pumping and gas venting means of FIG. 1, and

FIG. 3 is an enlarged sectional view of another oil "ice pumping and gas venting means that can be used to replace that shown by FIGS. 1 and 2.

FIG. 1, except for the gas venting means at the inlet of the oil pumping means, is the bottom portion of FIG. 1 of the previously mentioned Patent No. 3,259,307 which may be referred to for information as to the remainder of the compressor.

Referring now to FIGS. 1 and 2, a refrigerant compressor has an outer shell 10 within which are cylinders C1 and C2 having eccentric straps S1 and S2 respectively, connected to throws of vertically extending crankshaft 11. The latter has a vertically extending, off-center bore 12 therein, connecting at its upper portion with bearings which are not shown, and connecting at its lower portion, through opening 13 with a bearing 14. A hearing housing 15 extends around the bearing 14 and a portion of the crankshaft 11 below the bearing 14, and has an inturned lower portion 16 around a central opening 17. A thrust washer 18 having a central opening 19 coaxial with the opening 17, is seated on the housing portion 16. The bottom of the crankshaft 11 is seated on the washer 18. The housing 15 is supported above the bottom of the shell 10 by a coiled spring 20 that is supported on the center of the bottom of a cup 21, which, in turn, is supported on the bottom of the shell 10. The lower portion of the crankshaft 11, the housing 15, and the cup 21 are immersed in oil in sump 23. The cup 21 has openings 24 connecting with the sump 23. The bottom portion of the off-center bore 12 connects with a bore 25 within the crankshaft 11, which connects with the opening 19 in the thrust washer 18.

The construction described so far in connection with FIGS. 1 and 2, is essentially that disclosed in the previously mentioned patents. The bore 25 acts as a centrifugal pump, drawing oil through the openings 17 and 19, and forcing it through the bore 12 to the bearings.

Due to heat generated by the operation of the compressor, and to changes in pressure, gas is evaporated from the refrigerant liquid mixed with the oil, and appears at the bottom of the bore 25 where, due to the rotation of the crankshaft 11, bubbles accumulate, and which may increase in size sufiiciently to seriously restrict the oil flowing through the opening 19 into the bore 25.

This invention vents such a bubble before its size can increase sufficiently to seriously restrict the oil flowing through the opening 19 into the bore 25. A radial orifice 30 is formed in the crankshaft 11, with its inner end connecting with the bore 25 close to the axis of the crankshaft, and with its outer end connecting with a larger radial bore 31 which extends through the crankshaft 11 to its outer surface opposite annular space 32 below the bearing 14. The annular space 32 connects with opening 33 which extends through the bearing housing 15, and connects with the oil sump 23.

In the operation of the gas venting means of FIGS. 1 and 2, centrifugal force causes the refrigerant-oil mixture to pass through the opening 19 into the bore 25, and gas bubbles evolving from such mixture to flow through the orifice 30, the bore 31, the annular space 32, and the opening 33 into the sump 23. By making use of the full radius of the crankshaft 11 for the vent system 30-31, and by keeping the inlet of the orifice 30 as close to the center of rotation as possible, the suction produced by the gas expelled through the vent system will be sufiicient to overcome the reduction in pressure produced at the inlet of the orifice 30 by the effect of centrifugal force on the denser liquid in the bore 25, and each gas bubble will be drawn off by the vent system. Because of the small diameter and short radial length of the orifice 30, it can never become an oil pump of large capacity or high head,

and the loss of oil through it will be insignificant. The relatively small amount of oil pumped through the vent system will usefully entrain bubbles as they are formed.

FIG. 3 shows another form of combined oil pumping and gas venting means, of which the oil pumping means as well as the gas venting means are believed to be novel. In FIG. 3, the thrust washer 18 is omitted, and the crankshaft 11 is provided with a shoulder 35 which rests on the top of the housing 15 which would be aluminum. Also, the bore 25 is omitted, and a metal guide 36 formed as the frusturn of an inverted cone, is pressed onto the bottom of the crankshaft 11. The guide 36 has in its bottom, an oil inlet opening 37. The off-center bore 12 connects with the space within the interior of the guide 36. Also, a central bore 40 which converges from the bottom of the crankshaft 11 towards the orifice 30, is formed within the crankshaft, with its upper end connecting with the inner end of the orifice 30, the outer end of which connects with the inner end of larger radial bore 31 which extends to the outer surface of the crankshaft 11 opposite annular slot 32A in the housing 15. The bearing 14 is omitted, opening 13 connecting the off-center bore 12 with the surface of the housing 15 which is in contact with the crankshaft.

In the operation of FIG. 3, when part of a compressor, oil is drawn through the opening 37 into the guide 36' by centrifugal force, and is supplied through the bore 12 to the bearings of the compressor. Gas entering the opening 37 or evolved within the guide 36 is vented through the bore 40, the orifice 30, the bore 31, the annular slot 32A, and the opening 33 into the sump of the compressor. As in the case of FIG. 2, only a small amount of oil is vented with the gas, and such vented oil tends to entrain gas bubbles as they are formed.

What is claimed is:

I 1. In a refrigerant compressor having a vertical crankshaft, having a relatively large, vertical, off-center bore in said crankshaft, having means forming a relatively large oil inlet opening below the center of the bottom of said crankshaft, having an oil sump with a level above said opening, and having means forming a relatively large passage connecting said opening and said bore, the improvement comprising the provision of substantially radially extending passage means in said crankshaft, said passage means including an orifice having a relatively small length and having its inner end connected to said large passage near the axis of said crankshaft, and having its outlet connected through the remainder of said passage means to the outer surface of said crankshaft, said remainder of said passage means having a passage larger and longer than said orifice, and means connecting said passage means at said outer surface to said sump.

2. The invention claimed in claim 1 in which a housing extends around the lower portion of said crankshaft, and in which said means connecting said passage means to said sump comprises an annular passage in said housing around said crankshaft opposite said passage means, and an opening in said housing connecting said annular passage to said sump.

3. The invention claimed in claim 1 in which said means forming a relatively large passage connecting said opening and said bore, comprises a guide formed as a frustu m of an inverted cone, with its top around said bottom of said crankshaft, and in which said oil inlet opening is an opening in the bottom of said guide.

4. The invention claimed in claim 3 in which there is provided in said crankshaft a bore that connects with said inner end of said relatively small passage and which diverges therefrom to said crankshaft bottom.

5. The invention claimed in claim 4 in which a housing extends around the lower portion of said crankshaft, and in which said means connecting said passage means to said sump comprises an annular passage in said housing around said crankshaft opposite said passage means, and an opening in said housing connecting said annular passage to said sump.

References Cited UNITED STATES PATENTS 2,287,203 6/1942 Smith 230206 2,898,072 8/1959 Buschmann 230-206 3,049,285 8/1962 Doeg 230206 3,279,683 10/1966 Kleinlein 230-58 3,285,504 11/1966 Smith 230207 ROBERT M. WALKER, Primary Examiner.

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