US2963113A - Compressor lubrication system - Google Patents

Description

Dec. 6, 1960 R. w. AYLING I 2,963,113

COMPRESSOR LUBRICATION SYSTEM Filed Oct. 3, 1957 2 Sheets-Sheet 1 b FIGJ INVENTOR.

ROBERT W- AYLING ATTORNEY Dec. 6, 1960 R. w. AYLING COMPRESSOR LUBRICATION svsmu 2 Sheets-Sheet. 2

Filed Oct. 3, 1957 llllllllI-I lllllrlrrlrfl FIG.2

INVENTOR.

ROBERT W-AYLING A'ITO RN EY United States Patent COMPRESSOR LUBRICATION SYSTEM Robert W. Ayling, Syracuse, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Elicia ware ' Filed Oct. 3, 1957, Ser. No. 687,997

7 Claims. (Cl. 1846) The present invention relates to hermetic compressors and, more particularly, to hermetic compressors in which the crankshaft thereof is vertically disposed.

Generally, in hermetic compressors having vertically disposed crankshafts in which the motor is mounted over the compression mechanism, the bearing located between the motor and the compression mechanism handles the load of the compression mechanism and the motor and it has been found that the problem of lubricating this bearing is acute because of its remoteness from the oil sump. During shut-down of a compressor the lubrication passages above the oil sump level fill with refrigerant vapor. Upon start-up of the compressor, it is desirable to vent these lubrication passages so that the entrapped refrigerant will not starve the bearings of lubrication.

To avoid the danger of refrigerant gas blocking the lubrication system, normal practice has been to vent the lubrication system into the motor compartment. This practice has been accompanied by the disadvantage that quantities of lubricant are entrained into the suction gas stream which is utilized to cool the compressor motor. This entrained lubricant finds its way into the refrigeration circuit where an insulating film of lubricant is deposited on the heat exchanger surfaces, greatly limiting the capacity ofthe refrigeration system as a whole and also. reducing the supply of lubricant available for lubricating the compressor. The present invention envisions a unique bearing construction especially adapted for hermetic compressors wherein initially refrigerant gas and subsequently lubricant are vented into the crankcase. The chief object of the present invention is to provide a hermetic compressor having an improved bearing adapted to vent the lubrication system into the crankcase of the compressor.

Another object is to provide a compressor having a bearing which directs lubricant from the bearing into the crankcase to lubricate the compression equipment therein.

A still further objects is to provide a compressor having a vertically disposed crankshaft with a bearing substantially protruding into the motor compartment in which the bearing is adequately lubricated and has means for substantially directing the oil from said bearing into the compressor crankcase without entering the motor compartment and being entrained in the suction gas stream passing therethrough. These and other objects will become more apparent from the following description.

a The present invention relates to a reciprocating cornpressor, having-a compression mechanism operatively associated with a vertically disposed shaft. Also connected to the shaft and mounted above the compression mechanism is a suitabledriving motor. Between the motor and the compression mechanism is located a bearing which journals the shaft. The compressor is provided with a suitable lubrication pump which directs lubricant to the bearings; the bearing surface of the crankshaft is provided with a vertically disposed groove which is at ice least partially encompassed by the bearing surface. A partition separates the motor from the compression equipment and the groove in the crankshaft is in communication with the area adjacent the compression equipment. The compressor is of the type wherein the suction gas is utilized to cool the motor and the suction gas passes in the vicinity of the bearing. However, because of the construction of the bearing, the lubricant in the lubrication system and also the gaseous refrigerant therein are passed from the aforementioned bearing into the compression mechanism area wherein the lubricant passing from the bearing is utilized to lubricate the compression equipment without danger of the lubricant passing into the suction gas stream and entering the refrigeration circuit.

The attached drawing illustrates a preferred embodiment of my invention in which:

Figure 1 is a sectional view of a hermetic compressor unit employing the present invention;

Figure 2 is an enlarged sectional view of the bearing constituting the present invention; and

Figure 3 is a plan view of the bearing shown in Figure 2.

Referring to Figure 1, there is shown the compressor embodying the present invention. This compressor 2 comprises an upper shell 4 and a lower shell 5. These shells are provided with flanged sections 6 and 7 which are intended to meet in sealing contact. Also included in the compressor is a third shell 8 having a flange 9 which is joined to the flanges 6 and 7 by means of an annular weld 10. By this construction a hermetic housing is formed.

The flange of the shell 8 has provided therein suitable openings 11 to place the upper and lower sections of the shell in communication. The shell 8 also has a lower opening 12. Mounted within the inner shell 8 is a compressor block 15 which consists of a motor flange portion 16 and a crankcase flange portion 17 divided by a suitable partition 18. Also located in the compressor block are suitable cylinders 19 and 20. It is appreciated that any desired number of cylinders may be employed. Suitable pistons 21 and 22 are reciprocatingly mounted within the cylinders 19 and 20 and these pistons have mounted therein suitable'wrist-pins 23 and 24 which are in turn rotatably connected to the connecting rods 25 and 26. These connecting rods 25 and 26 are rotatably connected to the eccentric portion of the crankshaft 30.

At the extremities of the cylinders 19 and 20 are located suitable valve assemblies 31 and 32 which may be similar to those shown in the copending application in the name of Karl M. Gerteis, Serial No. 687,975, filed October 3, 1957.

These valve assemblies are retained within their respective positions by suitable spring retainers 33 and 34. These spring retainers 33 and 34 are biased between the valve assemblies 31 and 32 and the shell 8, thereby retaining the valve assemblies in position.

Two circular sealing flanges 37 and 38 are provided on the compressor block in concentric spaced relationship. These particular flanges are provided with suitable 0 rings 39 and 40 which seal the space between the block and shell 8 thereby defining an annular space 41 into which gas compressed within the cylinders 19 and 26 is discharged. The discharge gases are passed from the compressor through the discharge passage 42 which is a short connecting tube extending through the shell 8 and the shell 5. If it is desired, suitable cavities may be incorporated in the annular space 41 to impart a m ufiling effect to the discharge gases which are passed from the various cylinders of the compressor. In order to introduce these gases into the various cylinders, suction gas is introduced through the opening 63 in the shell 4. This opening 63 permits suction gas to pass into the motor compartment 13 and through the various suction ports 45. The suction ports 45 are connected to annular spaces 90located beneath the valve assemblies 31 and 32. A more detailed description of the compression side of the compressor is disclosed in the copending application in the name of Karl M. Gerteis, Serial No. 687,977, filed October 3, 1957.

It will be noted at this point that the various suction openings 45 are the only openings located in the area of partition 18 with the exception of the bearing 46 into which the crankshaft 30 is journalled. This crankshaft 30 comprises a straight portion which is adapted to be connected to the motor 56, a bearing portion 51 which is adapted to be journalled within the bearing 46, an eccentric portion adapted to be connected to the various connecting rods which are operatively associated with the pistons, a counterweight section 53 which is adapted to aid in counteracting the unbalance of the eccentric portion 52 and a lower bearing portion 54 which will be described more fully hereinafter.

The motor 56 comprises a stator 57 which is mounted within the motor flange portion 16 of the compressor block. The stator is inductively connected to the rotor 58 which is force-fitted onto the crankshaft section 50. Located and attached to the rotor 58 is a suitable counterweight 59 which is also adapted to aid in counteracting the unbalance of the eccentric portion of the crankshaft.

In order to direct electric current from a suitable source to the stator 57', a suitable plug 60 is provided in the shell of the compressor in such a manner as to preserve the hermetic nature of the compressor. This plug 60 is connected by suitable conductors 61 to the stator 57.

The crankshaft 30 is journalled within a lower bearing 65 which is mounted in the lower bearing head 64. This lower bearing head 64 is maintained in position by a suitable snap ring 62 which seats within an annular groove in the compressor block. The bearing head also includes a thrust bearing 66 which has a central opening 67, the function of which will be described more fully hereinafter. Located in the lower portion of the crankshaft adjacent the bearing portion 54 is a concentric hole 68 which constitutes the eye of the impeller of the pump which lubricates the various bearings in the compressor. The eye is a vertically extending hole in communication with the radial hole 6 which extends to the annular space 71. Also located in the shaft is the vertical passage 70 which is in communication with the radial hole 69. Oil which is pumped into the annular space 71 passes through the passage 72 into the filter 73 in which the oil is suitably filtered. The oil that is forced into the vertical passage 70 passes upward to the discharge openings 75 which lubricate the connecting rods and the bearing 46, the construction of which will be defined more fully hereinafter.

The operation of the compressor is as follows: Suction gas is introduced through the opening 63 and the gas passes over the motor 56 suitably cooling the motor and then passes through the suction inlets 45 through the valve plates 31 and 32 into the cylinders 19 and 20 wherein the gas is compressed. The gas is then, on a discharge stroke, passed into the annular manifold 41 wherein, if desired, a suitable muffler construction may be employed and then passed through the discharge opening 42 out of the compressor.

With respect to the lubrication system of the unit, oil is stored in the sump 76 of the compressor which is the lower portion of the shell and is maintained at an approximate level shown as 77 in a manner to be described hereinafter. It will be noted that, as a result of the openings 11 in the flange section 9 of the shell 8, the motor compartment is vented to the annular space between the shells 5 and 8. Therefore, the lubricant in this space is at suction gas pressure. It will be noted that the crankcase section 14 is isolated from the motor compartment 13 by means of the partition '18 which lies between the motor flange section 16 of the compressor block 15 and the crankcase section 14 of the compressor block. During operation as a result of gaseous refrigerant bypassing the compressor pistons a pressure greater than suction pressure will become evident after a short interval of operation within the crankcase 14. As a result, this gas pressure will substantially force the lubricant in the crankcase 14 out of the crankcase through suitable holes 12' in the lower bearing insert 64 into the sump and up the annular chamber between the shells 5 and 8. A two-level oil sump results because of the different pressures acting on the oil in the oil sump 76. This is more fully described in the copending application in the names of Karl M. Gerteis and Robert W. Ayling, Serial No. 687,976, filed October 3, 1957.

As the compressor rotates under the influence of the motor 56, oil passes through the opening 67 of the thrust bearing 66 into the eye 68 drilled in the lower portion of the crankshaft 30. Since the lower bearing 54 is submerged in oil, the oil in the radial passage 69 as a result of centrifugal force will be cast outwardly, a portion passing into the annular space 71 through the passage 72 through the filter 73 and into the crankcase. This is a standard bypass type filter. The remainder of the oil as a result of the centrifugal force will be urged upwardly above the surface of the oil in the sump through the passage 70 to the various bearing portions of the compressor.

At this point, it is immediately apparent that two problems arise in the operation of the compressor. Firstly, the vertical passage 70 located within the crankshaft 30 will, after long shutdowns, be filled with refrigerant vapor at levels above the oil sump level indicated at 77. At startup after a prolonged shutdown, it will be necessary to remove this refrigerant vapor in order to prevent a vapor lock, which will starve the bearing surfaces and ultimately result in bearing failure. The second problem is that, should uncontrolled venting be permitted, the lubricant passing from the hearing will pass over the outside surface of the bearing 46 and ultimately find its way to the various suction openings 45. This flow will be further encouraged by the passage of suction gas over the motor and bearing prior to entrance into the openings 45. The admission of large quantities of oil into the compression equipment will necessarily have an adverse eifect upon the valves thereof and furthermore, in normal operation, the passage of quantities of lubricant into the refrigeration circuit itself, will coat the various heat exchange surfaces with an insulating fihn which will drastically limit the heat exchange qualities of these surfaces.

Referring to Figure 2, there is shown a fragmentary sectional view of the bearing construction utilized in the present invention. It will be noted that the vertical passage 70 extends up into the bearing 46. By means of two passages 81 and 82 the oil is permitted to reach the bearing surfaces for the purpose of lubricating said surfaces. It will be noted that these two passages 81 and 82 extend into two vertically extending grooves 83 and 84 which are located in the bearing surface of the shaft. A better view of these grooves is shown in Figure 3.

It will be noted that the bearing itself is constructed of the bearing housing 46, having therein two bearing inserts 86 and 87. These inserts are spaced from one another and include an open space 85 therebetween. It will be noted from Figure -'2 that the grooves 83 and 84 extend beyond the bearing inserts 86 and 87.

With respect to the groove 83, this groove extends upwardly but does not reach the upper edge of the bearing insert 86; however, the lower portion of this groove 83 extends below the bearing insert 86 and places the lubricant passing through the passage 81 into communication with the annular space 85. With respect to the insert 87, it will be noted that the vertical extending groove 84 overlaps both sides of the bearing insert 87, thereby placing the annular space 85 in communication with the crankcase.

Upon startup of the compressor any refrigerant gases lying within the passages 81 and 82 in grooves 83 and 84 and annular space 85 will be permitted by the buildup of pressure as the result of the rotation of the previously described lubricant pump mechanism to be driven into the crankcase cavity, thereby permitting oil to flow in these various passages, grooves, and spaces. As the oil reaches the various surfaces, the surfaces are lubricated and the oil freely passes from the upper bearing surface 86 into the annular space 85. A portion of the oil aids in lubricating the surface 87 and the remainder of the oil passes through the groove 84 into the crankcase. This free flow of oil not only lubricates the surfaces but also carries heat therefrom. By this type of construction, all the oil and refrigerant is encouraged to flow into the crankcase discouraging any flow of lubricant into the motor compartment 13 wherein the particles of oil might be picked up or drained by the suction gas into the various suction ports of the cylinders and ultimately find their way into the refrigeration circuit itself.

An advantage of the present construction is that all the oil which is passed to the bearing 46 finds its way into the upper portion of the crankcase 14. As the oil passes into the crankcase, it falls upon the eccentric portion of the crankshaft and is thrown outwardly, finding its way into the various cylinders and thereby providing lubrication to the cylinder walls, pistons, and the wristpins of compression equipment.

In a construction of the type shown in Figure 1 it is important to the successful operation of the compressor that the pressure difference existing between opposite ends of the bearing be maintained. Any uncontrolled venting of the bearing Will defeat this aim. By the positive venting construction of the bearing of the present invention oil is disinclined to enter the motor compartment in a manner which provides a counterflowing oil stream which discourages the passage of refrigerant gas from the crankcase to the motor compartment. The maximum load on the crankshaft occurs when the pistons in the cylinders are approaching top dead center which is the end of the compression stroke. Naturally, the eccentric portion of the crankshaft will be at a point closest to the particular piston at top dead center. Therefore, the maximum load on the crankshaft will be on the opposite side of the crankshaft or on the side opposite the eccentric. It has been found that the opposite side of the shaft is not fully loaded. It is, therefore, possible to place the vertical groove on the same side of the shaft as the eccentric since this is a comparatively unloaded section of bearing shaft.

The present invention'provides a bearing construction which compensates for the lubrication requirements of the compressor bearing, and also provides lubrication for the compression equipment itself in an inexpensive and unique manner. Furthermore, this construction avoids the passage of quantities of oil into the motor compartment where the oil may find its way into the suction ports of the; compression equipment and ultimately affect the heat exchange qualities of the various heat exchange members in the refrigeration circuit. This is accomplished with the added feature that upon startup the possibilities of vapor lock to prevent adequate lubrication of the bearings is avoided by the positive venting of the bearings and the various oil passages in the crankshaft.

While I have described a preferred embodiment of my invention, it will be understood my invention is not limited thereto, since it may be otherwise embodied within the scope of the following claims.

I claim:

1. In a reciprocating compressor the combination of cylinder means, a piston reciprocatingly mounted in said cylinder means, a crankcase, an upper bearing, a lower bearing, a vertically extending crankshaft journalled in said bearings and operatively connected to said piston, a motor connected to said crankshaft, a partition separating the motor from the crankcase, a lubrication pump located adjacent said lower bearing, a passage extending vertically in said crankshaft in communication with said pump, said upper bearing including first and second spaced bearing surfaces, a first groove in said crankshaft, a second groove in said crankshaft, said first and second grooves being in communication with the vertically extending passage in the crankshaft, said first groove being at least partially encompassed by the first bearing surface, the second groove being partially encompassed by the second bearing surface, said first and second grooves being in communication with an annular space between the first and second surfaces and the sec ond groove being connected to said crankcase, means for passing suction gas over the motor to cool said motor, whereby the compressor is lubricated without substantially entrapping any lubricant in the suction gas.

2. A reciprocating compressor comprising cylinder means, a piston reciprocatingly mounted in said cylinder means, a crankcase, a vertically extending crankshaft operatively connected to said piston, a motor compartment, a motor located in said compartment and corn nected to said crankshaft, means for passing suction gas over said motor, a partition separating the crankcase and the motor compartment, an upper bearing located in and extending through said partition, a lower bearing, 3. lubrication pump located adjacent said lower bearing, said crankshaft being journalled in said bearings, a vertically extending passage in said shaft in communication with said pump, a groove in said crankshaft partially encompassed by said upper bearing, said groove being in communication with the vertically extending passage and also in communication with the crankcase whereby lubricant and gases in the lubrication passages are vented into the crankcase without any substantial introduction of lubricant into the motor compartment.

3. The compressor according to claim 2 in which the crankshaft has an eccentric portion and the groove is located on the same side of the shaft as the eccentric portion.

4. The compressor according to claim 3 in which the motor is mounted above the cylinder means so that lubricant from the groove passes into the crankcase and is cast outwardly to lubricate the cylinder means.

5. The compressor according to claim 2 in which the bearing comprises first and second spaced annular bearing-surf-aces separated by an annular space, a second groove in said crankshaft, said first mentioned groove being partially encompassed by the first surface and the second groove being partially encompassed by the second surface, said first and second grooves also being in communication with the annular space.

6. A hermetic compressor comprising a shell; a compressor block located in said shell and defining cylinder means, a crankcase, a motor cavity, and a partition between said motor cavity and crankcase; a bearing located in said partition; :a crankshaft; a piston reciprocatingly mounted in said cylinder means and operatively connected to said crankshaft; a motor located in said motor cavity and operatively connected to said crankshaft; said bearing having a surface; said crankshaft having a surface journalled against said bearing surface; a groove disposed in one of said last mentioned surfaces substantially parallel to the crankshaft axis; means for passing lubricant to said groove; means connecting the groove and the crankcase; means for maintaining the motor cavity at suction gas pressure and means for maintaining the crankcase at a pressure greater than suction gas pres- 7 sure, whereby the suction gas passes through the motor cavity without substantially entrapping any lubricant in said suction gas.

7. A compressor comprising a compression mechanism, a motor mounted above said compression mechanism, said motor and compression mechanism being connected by a vertically extending shaft, a partition separating the motor from the compression mechanism, a bearing located between said motor and said compression mechanism and journalling said shaft, means for introducing lubricant to said bearing, a vertically extending groove located in said shaft and being at least partially encompassed by said bearing, said groove being in communication with an area adjacent said compression mechanism and with said crankcase, whereby lubricant from said bearing is passed to and at least partially lubricates said compression mechanism, and means for passing suction gas over said motor to cool said motor, said gas passing adjacent said bearing without substantially entrapping any lubricant in said gas stream.

References Cited in the file of this patent UNITED STATES PATENTS 946,133 Jahnke Jan. 11, 191.0 2,038,131 Richard Apr. 21, 1936 2,725,118 Clark Nov. 29, 1955 2,743,627 Christensen May 1, 1956 2,752,088 Borgerd June 26, 1956 FOREIGN PATENTS 73,776 Germany Apr. 2, '1894 568,991 Great Britain Apr. 30, 1945 65,377 Denmark Jan. 20, 1947 768,058 Great Britain Feb. 13, 1957

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