US3312387A - Lubrication system for rotary compressor - Google Patents

Description

April 967 H. J. CASSIDY ETAL 3,312,387

LUBRICATION SYSTEM FOR ROTARY COMPRESSOR Filed Dec. 30. 1964 2 Sheets-Sheet 1 April 4, 1967 H. J. CASSIDY ETAL LUBRICATION SYSTEM FOR ROTARY COMPRESSOR 2 Sheets-Sheet 2 Filed Dec. 30, 1964 rrlyjcasaa'agy United States Patent 3,312,387 LUBRICATION SYSTEM FOR ROTARY COMPRESSOR Harry Joseph Cassidy, York, Pa., and William Donald Beck, Columbus, Ohio, assignors, by direct and mesne assignments, to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Filed Dec. 30, 1964, Ser. No. 422,348 1 Claim. (Cl. 230-152) This invention relates generally to compressors, and more particularly to improvements in lubrication systems for rotary, sliding vane compressors.

It is well recognized that rotary compressors offer many advantages over convention-a1 reciprocating compressors, particularly in regard to improved reliability and decreased vibration and noise. On the other hand, the supply of a lubrication and cooling medium for the bearings and seals in a rotary compressor often presents many problems, particularly in compressors used in refrigeration systems. For example, means for directly injecting lubricant into the compressor chamber, while commonly found in air compressors and vacuum pumps, has been thought to be impractical in refrigerant compressors. The reason for this is that the lubricant used in a refrigeration system contains a high proportion of dissolved refrigerant which is miscible with the oil. When the refrigerant and oil mixture is injected into the compression chamber adjacent to the suction port, the refrigerant vaporizes out of the oil and expands under the relatively lower pressure conditions existing in this area. This results in the refrigerant vapor filling up the suction volume and retarding the flow of suction gas into the compression chamber. This action has the effect of reducing the capacity of the compressor and is detrimental to its operating efficiency.

Another problem inherent in the operation of the ordinary rotary compressor is the failure to maintain a satisfactory flow of lubricant to critical components such as bearings and seals. It will be appreciated that the rotor, spinning at high rpm, tends to throw any lubricant outwardly from the rotational axis. As a result, it is difficult to provide satisfactory flow of lubricant to the bearings and seals associated with the drive shaft which extends along the rotational axis of the rotor. According to the present invention, oil is forced under a positive'pressure into at least certain of the bearings and seals to insure that they are cooled and lubricated in a satisfactory manner. 7

It is, there-fore, a principal object of the present invention to provide an improved rotary sliding vane compressor especially adapted for use in a refrigeration system.

Another object of the invention is to provide a lubrication system for a rotary compressor employing means for directly injecting a mixture of oil and refrigerant into the compression chamber in such a way that a substantial separation of the refrigerant from the lubricant is effected without materially retarding the flow of suction gas into said compression chamber.

Still another object of the invention is to provide a positive means for insuring satisfactory flow of lubricant to bearings and seals within the compressor.

Additional objects and advantages will be apparent from a reading of the following detailed description taken in conjunction with the drawings wherein:

FIGURE 1 is a cross-sectional view of a compressor constructed in accordance with the principles of the present invention;

FIGURE 2' is a cross-sectional view taken along the plane of line 22 of FIGURE 1; and

FIGURE 3 is a cross-sectional view taken along the plane of line 3- 3 of FIGURE 1.-

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Referring now to the drawings, and particularly to FIGURE v1, the compressor of the present invention comprises a housing, generally designated by reference character A, comprising a cylinder section 10, end plates 12 and 14, and a refrigerant gas chamber 16, all of said parts being connected by suitable means, such as elongated cap screws 17.

Housing A includes an internal cavity defined by a cylindrical peripheral wall 20 in cylinder section 10 and end walls 22, 24 formed by the inwardly facing surfaces of end plates 12 and 14. Supported for rotation within the cavity by bearings 18, 19 is a cylindrical rotor 25 which is mounted within the cavity in eccentric relation to the peripheral wall to provide a crescent shaped compression chamber 26 between said peripheral wall and side walls 22, 24.

Communicating with opposite ends of the compression chamber 26 are a suction port 23 and a discharge port 29 through which refrigerant gas is respectively admitted and discharged from the compression chamber. Discharge port 29 has associated therewith a discharge valve assembly 30 of any conventional type. Rotor 25 comprises a cylindrical hub 32 connected to a drive shaft 34 which is journalled for rotation by bearings 18 and 1-9 in end plates 12 and 14 respectively, and a plurality of vanes as received within a plurality of transversely extending slots 38 in said hub, said vanes being reciprocatively movable within slots in the hub member. In order to maintain the vane tip portions in engagement with the peripheral wall 20, said vanes are urged radially outwardly by a plurality of pins 40 which are operatively associated with each pair of diametrically opposed vanes. The pins 40, which extend through holes (not shown) in the hub and drive shaft, resiliently bias the vanes apart by means of small springs 42 received in complementary bores 43 in the under side of each vane.

As pointed out in the preliminary remarks, means are provided for directly injecting the lubricant and oil mixture into the compression chamber 26 in such a way that the refrigerant released from the mixture Will not fill up the suction volume to impede flow of the suction gas therein. vAs used herein, the term suction volume is meant to include any portion of the compression cavity which is, at any position of the vanes, in fluid communication with the suction port 28. It will be appreciated that as the vanes sweep through the compression cavity in the direction indicated by the arrow (FIG. 2), the volume, or extent of the cavity, open to the suction port 28 varies. The position of the vanes as shown in FIG- URE 2 is such that the vane adjacent to the lower edge. 28a of the suction port is just about to close oif the suction volume. Consequently, the suction volume at this point includes the entire volume in back of the leading vane, that is, the vane ahead of the one adjacent the edge 28a of the suction port. Therefore, the point where suction is closed is the point in the cavity just ahead (in the direction of rotation) of a leading vane when an adjacent trailing vane passes the last point where the suction port intersects the compression cavity.

Means for injecting the oil-refrigerant are provided by. a fluid passage 46 communicating with the sump portion 47 of the refrigerant gas chamber 16, said passage registering with a fluid passage 48 through the cylinder section. At opposite ends of the cylinder section, small grooves 49a, 4912 are provided in the face thereof to permit the diluted lubricant to be injected into said compression chamber at the point, defined above, where the suction volume is closed. 7

Between the point where suction is closed and the discharge port, the maximum pressure reached at any time varies, depending on the radial distance between the hub periphery and peripheral cavity wall 20. Immediately 9 adjacentto the discharge port, over compression occurs just before the discharge valve opens. On the other hand, at a point just beyond the point where the suction Volume is closed, the maximum pressure reached is substantially below discharge pressure. Since the refrigerant-oil mixture, is at discharge pressure, due to the factv that refrigerant vapor above the mixture in the sump is always at discharge pressure, the refrigerant in the oil vaporizes and is released from the oil when it is injected into the lower pressure area in the cavity.

At the same time, it can be seen that while the point at which the refrigerant-oil mixture is injected is under a lower pressure than that which exists in the refrigerant gas chamber sump, the released vapor is not permitted to expand :into the suction volume since the suction volume has been closed at this point by a vane passing the lower edge 28a of the suction port.

As the rotor is driven in the direction of the arrow shown in FIGURE 2, radial movement of the vanes first increases until the vane is at a point X intermediate the suction and discharge ports, said point being diametrically opposite to the point adjacent the discharge port where the hub is substantially contiguous with the peripheral wall 20. From then on, the vanes collapse radially inwardly until they reach a point just beyond the discharge port 29.

This cyclical movement of the vanes produces a corresponding expansion and contraction of the volume of the spaces underneath the vanes, said spaces being defined by the, end walls 22, 24,the.lower edge of each vane, and the bottom of the vane receiving slots 38.

The oiland lubricant mixture which is injected through the injection port flows through the clearance space between the ends of the rotor hub 32 and the end walls 22, 24 of the compression chamber 26, and also between the faces of the vane and the adjacent side portionsof the slots into which the vanes are received, ultimately filling up the space underneath each vane when the vanes are substantially fully extended, at or near point X.

The end plate 12 is provided with a recessed portion 55 (the position of whichis indicated by dotted lines in FIGURE 2) in fluid communication with the space between the front bearing 18 and the rotary seal 58 through fluid passage 56. As the spaces underneath the vanes approach their fully contracted position, which cor-responds to the maximum pressure of the lubricant in said spaces, the ends of said space pass into registered relation with recessed portion 55. The vanes, therefore, function as pumps into which oil is circulated and then compressed, finally being discharged through the passage 56 to the space between the bearing and the seal.

The gas chamber .portion, 16 of the housing A comprises a pair of chambers 60, 62 provided by a partition shown in FIGURE 3. The chamber or compartment 60 shown in the upper left-hand corner of the figure is a suction chamber into which suction gas is passed from the evaporator. This suction gas compartment is in communication with the suction port shown in FIGURE 2. The. other compartment 62 is the gas discharge department into which the gas under compression is passed through the discharge valve assembly 30 and an opening 66 in the rear end plate 14. Discharge gas passes downwardly through a pair of oil separating devices 68a, 68b and flows outwardly through the discharge passage 70 having an external connection 72 and a conduit leading to the condenser.

As the gas passes through the oil separating media, the oil coalesces and tends to separate from the refrigerant. Consequently, an oil level indicated at L is formed in the lower or sump portion 47 of the gas chamber which communicates through passages 46 and 48 and oil injection ports 49a and 49b. Since the oil is under discharge pressure, there is a positive force acting on the oil to force it to the compression chamber.

While the ,unit described herein shows only a single passage in the front end plate, it is obvious that additional passages may be provided in the rear end plate 14 for lubrication of the rear bearing. It will also be appreciated that additional passages may be provided for lubricating other areas as required.

While this invention has been described in connection with a certain specific embodiment thereof, it is to be understood that this is by way of illustration and not by way of limitation; and the scope of this invention is defined solely by the appended claim which should be construed as broadly as the prior art will permit.

What is claimed is:

A compressor comprising a housing having a cavity therein, said cavity being defined by a generally cylindrical peripheral wall and opposed end walls; a rotor including a generally cylindrical hub having a plurality of substantially radially extending slots, and a shaft extending axially from said hub; means for rotatably journaling said rotor in said cavity, said means including at least one bearing supporting said shaft; said hub, said peripheral wall, and said opposed end walls defining a crescent-shaped compression chamber, said rotor and said end walls defining clearance spaces therebetween; means defining suction and discharge ports communicating with said compression chamber; a plurality of vanes carried by said hub, said vanes being received in said slots for reciprocative movement so that the tip portions thereof are maintained in engagement with said peripheral cavity wall, said vanes defining a plurality of movable pockets therebetween, the volume of each pocket expanding from said suction port to a point intermediate said suction and discharge ports and contracting from said intermediate point in a direction toward said discharge port; means defining a space under each of said vanes, the volume of which varies as said vanes reciprocate within said hub slots; means defining a fluid injection port opening into said compression chamber at a point circumferentially spaced from said suction port by a distance equivalent to the space between a leading vane and an adjacent trailing vane when said trailing vane passes the end of said suction port; means for supplying refrigerant diluted lubricant to said injection port, said lubricant flowing from said compression chamber through said clearance spaces to the spaces under each of said vanes to fill said spaces at a point when the volume therein is at a maximum; and fluid passage means in one of said cavity end walls, said fluid passage means having a port at one end thereof located adjacent to the discharge port and registering with the spaces under said vanes as the rotor is driven in the direction toward said discharge port, the other end ofsaid fluid passage means being in fluid communication with said bearing, whereby the lubricant under said vanes is pumped by the contraction of said vanes through said fluid passage means to said bearing as the spaces under said vanes are brought into registration with said fluid passage means port.

References Cited by the Examiner UNITED STATES PATENTS 1,732,039 10/1929 Cuthbert 230-153 1,970,033 8/1934 Dennedy 230-152 2,013,777 9/1935 Dennedy 230-152 2,275,774 3/1942 Kraissl 230-152 2,832,293 4/1958 Adams et al 230-207 References Cited by the Applicant UNITED STATES PATENTS 1,928,300 9/1933 Peltier. 1,953,253 4/1934 Ogilvie. 2,455,297 11/1948 Curtis et al.

DONLEY J. STOCKING, Primary Examiner. MARK NEWMAN, Examiner.

R. M. VARGO, -W. J. GOODLIN, Assistant Examiners.

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