Scroll compressor with lubrification of seals in back pressure chamber

Abstract: A scroll compressor lubrication system includes a number of embodiments where lubricating oil impinges off surfaces adjacent to the orbiting scroll. The impinged oil creates a lubrication mist, which is deposited on the back surface of the orbiting scroll baseplate (24). The surface of the orbiting scroll onto which the oil has been deposited rubs against and carries the oil to the back chamber seals (32,34) and to the back chamber (74). The seals thus are being lubricated by oil transfer from the back surface of the orbiting scroll to the seals. Sine the oil is deposited on the surface of the orbiting scroll, while it is exposed to suction pressure, only minimal pressurization of oil is required. Thus, there is no damage to the back pressure chamber seals due to over pressurization.

Description: BACKGROUND OF THE INVENTION This invention relates to a scroll compressor with a lubrication system for indirectly conveying lubricant to the back pressure chamber seals. Scroll compressors are becoming widely utilized in refrigerant compression applications. Essentially, a scroll compressor consists of two scroll members with one orbiting relative to the other. Each scroll members includes a spiral. wrap extending from a base. The spiral wraps interfit to define compression pockets. As the orbiting scroll moves relative to the non-orbiting scroll, the size of compression pockets becomes smaller and fluid trapped inside the pockets becomes compressed. There is a separating force generated from the compressed fluid tending to bias the two scroll members away from each other. To counteract the separating force, it is known e.g. from WO 95 08713 A to tap a pressurized fluid to a chamber behind the base of one of the scroll wraps. Two seals typically define the boundaries of the chamber. Pressure in the back chamber acting over the scroll base creates a force tending to bias the scroll members back together, and acts in a direction opposite to the separating force discussed above. The back pressure chamber seals are subject to many challenges and, in known compressors, often fail. One cause of seal failure is the lack of oil to lubricate seals. It has been proposed in the past to deliver lubricant directly to the back chamber seals. In such proposals the oil needs to be additionally pressurized, thus creating complications. First, the compressor needs means for pressurizing the oil. Also, the seals may be damaged due to overcompression of the oil in the supply line. Also, the slight axial movement of the orbiting scroll can overcompress oil in the back chamber, creating another cause of seal damage. SUMMARY OF THE INVENTION In a disclosed embodiment of this invention, lubricant is indirectly supplied to the outer and inner back pressure chamber seals of the scroll compressor. That is, the lubricant impinges off of a surface adjacent to the back pressure chamber seals, and then is carried to the back pressure chamber seals. In this way, adequate lubrication is provided to the back pressure chamber seals. In one embodiment, the lubricant is directed to an outer seal by impinging off the crankcase towers or compressor shell, and in a second embodiment, the lubricant is directed to an outer seal by impinging off an end face of the crankcase adjacent to the outer seal or off a surface of an antirotation coupling. In either case, an oil mist is created which is deposited on the rear face of the orbiting scroll plate as the orbiting scroll rotates. As the orbiting scroll continues to rotate the rear face of the orbiting scroll, which is covered by oil mist, is moved over and comes in contact with the stationary back chamber outer seal. Thus, providing effective oil lubrication of the seal. Lubricant is preferably also supplied to the inner seal. In one embodiment, a passage extends through the hub of the orbiting scroll. The oil expelled through this passage impinges on an inner portion of the crankcase. Again, an oil mist is created by this impingement, and the mist is deposited on the rear face of the orbiting scroll, from which it is carried to the inner seal. It should be noted that since the oil is deposited on the surface of the orbiting scroll while it is exposed to suction pressure, only minimal oil pressurization is required; just enough to create an issuing jet. Thus, no additional means to pressurize the oil are required except as provided by the existing oil delivery system. Although the present invention as specifically disclosed has a back pressure chamber disposed behind the orbiting scroll, it should be understood that the invention also extends to a back pressure chamber defined behind the non-orbiting scroll. These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a cross-sectional view of a scroll compressor incorporating the present invention. Figure 2 shows a view of a crankcase according to the present invention. Figure 3 shows a view of a rear face of an orbiting scroll according to one embodiment of the present invention. Figure 4 shows a view of a rear face of an orbiting scroll according to another embodiment of the present invention. Figure 5 shows a cross-sectional view of an orbiting scroll with further definition of the features of the present invention. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT A scroll compressor 20 is shown in Figure 1 incorporating a non-orbiting scroll 22 and an orbiting scroll 24. As known, a shaft 26 drives the orbiting scroll through a hub 28 to orbit relative to the non-orbiting scroll 22. As known, an oil passage 23 extends through shaft 26 to deliver oil to a chamber 25. Oil in chamber 25 is then available for distribution to different locations of scroll compressor. A tap 30, shown schematically in Fig. 3, taps pressurized fluid from chambers between the wraps of the orbiting and non-orbiting scrolls to a back pressure chamber 74 defined between seals 32 and 34. Seals 32 and 34 are shown to be received in respective circumferentially extending grooves 62 and 64 in crankcase 38. A passage 33 receives oil from chamber 25, and extends from the inner surface of the hub 28 to a downwardly extending tap 68. Oil leaving tap 68 impinges on end face 80 of the crankcase 38 adjacent to the outer seal 32. Another tap 36 can be added. This tap extends downward. Oil leaving tap 36 impinges off the antirotation coupling 66, adjacent to the outer seal 32. Another tap 35 extends from chamber 25 through the inner hub groove 50, and provides a passage for impinging oil off of a surface 37 on the crankcase. Another passage 40 extends from chamber 25 outwardly through an outer peripheral wall of the orbiting scroll 24. The oil which leaves the passage 40 through the opening 72 impinges off the crankcase tower 42 or off the scroll compressor shell surface 70. In all of the above arrangements, the oil impingement creates a mist, and the mist is delivered onto a rear face 76 of the orbiting scroll. The rear face of the orbiting scroll then carries the mist to the inner and outer seals 32 and 34, and back chamber 74. The tap 35 provides lubrication for the inner seal 34 and the tap 68 and 36, and opening 72 provide lubrication for the outer seal 32. It should be understood that taps 35, 36, 68 or opening 72 can be used singularly, or in combination with each other. Further, by delivering the oil to the rear of the orbiting scroll at even one location, will improve the lubrication of both seals as the movement of the orbiting scroll causes the oil to be distributed to each and around the entire circumference of the respective seals. Shown in Figure 2 are surfaces 37 and crankcase towers 42. Oil expelled from tap 35 impinges on surface 37 and oil expelled from passage 40 through opening 72 which is located in line with crankcase tower 42 impinges on surface of crankcase tower 42. As shown in Figure 3, oil expelled from tap 36 impinges off end face 80 of crankcase 38 and is directed onto a rear face of orbiting scroll. Figure 4 shows passage 40 extending outwardly to an outer peripheral surface of the orbiting scroll 24. Oil expelled from this passage impinges off crankcase tower 42 or compressor shell 70. Figure 5 shows a detail of the passage 35, wherein groove 50 is formed on the inner peripheral surface of the hub 28 to pass lubricant from chamber 25 to groove 50 and to tap 35. The groove 50 is formed between a bearing bushing 51 and the inner surface of the hub. Preferred embodiments of this invention have been disclosed; however, a worker of ordinary skill in the art would recognize that certain modifications come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.

Claims: A scroll compressor comprising: a first scroll (24) having a base and a spiral wrap extending from said base; a second scroll (22) having a base and a spiral wrap extending from said base; said spiral wraps of said first and second scrolls interfitting to define compression chambers; a tap (30) for fluid pressure extending to a back pressure chamber (74) behind said base of one of said first and second scrolls (22,24); seals (32,34) being positioned at radially inner and outer positions to define inner and outer boundaries for said back pressure chamber (74); characterised by a lubricant supply system (33,35,36,40,68,72) for supplying lubricant to surfaces adjacent to said inner and outer seals (32,34) such that said lubricant is delivered outside said back pressure chamber (74) to both said inner and outer seals (32,34). A scroll compressor as recited in claim 1, wherein said first scroll (24) orbits relative to said second scroll (22), and said back pressure chamber (74) is defined behind said orbiting scroll base. A scroll compressor as recited in claim 2, wherein a crankcase is positioned rearwardly of said base of said orbiting scroll (24), and said seals (32,34) are received in grooves (62,64) in said crankcase. A scroll compressor as recited in claim 3, wherein said lubricant supply system (33,35,36,40,68,72) includes a passage (33) directing a lubricant jet to impinge off of a face of said crankcase behind said base of said orbiting scroll (24), and slightly radially outwardly of said outer seal (32). A scroll compressor as recited in claims 3 or 4, wherein said lubricant system (33,35,36,40,68,72) includes a passage (40) extending radially outwardly through an outer peripheral surface of said scroll (24) and for directing a lubricant jet to impinge off a crankcase tower (42) located on a an outer periphery of said crankcase and past said base of said orbiting scroll (24). A scroll compressor as recited in claims 3 or 4, wherein said lubricant system (33,35,36,40,68,72) includes a passage (40) extending radially outwardly through an outer peripheral surface of said scroll (24) and for directing a lubricant jet to impinge a portion of a compressor housing shell (70). A scroll compressor as recited in any of claims 3-6, wherein said lubricant supply system (33,35,36,40,68,72) includes a passage (35) extending through a hub (28) of said orbiting scroll (24) and for directing a lubricant jet to impinge off an inner surface of said crankcase to lubricate said inner seal (34). A scroll compressor as recited in claim 7, wherein said hub (28) of said scroll compressor includes a groove (50) defined between a hub (28) and bearing bushing (51), said bearing bushing (51) being positioned between a shaft (26) for driving said orbiting scroll (24) and said groove (50), said lubricant supply system (33,35,36,40,68,72) including a passage (35) extending radially outwardly through said hub (28) and communicating with said groove (50). A scroll compressor as recited in any of claims 1-8, wherein said lubricant supply system (33,35,36,40,68,72) includes a passage (36) directing a lubricant jet to impinge off a surface of an anti-rotation coupling (66). A scroll compressor as recited in claim 1, wherein said lubricant supply system (33,35,36,40,68,72) comprises a first passage (33) delivering lubricant to a location radially outward of said outer seal (32). A scroll compressor as recited in claim 1, wherein said lubricant supply system (33,35,36,40,68,72) comprises a second passage (35) delivering lubricant to a location radially inward of said inner seal (34).

Inventors: LIFSON ALEXANDER, LIFSON, ALEXANDER
Applicants: CARRIER CORP, CARRIER CORPORATION
Application year: 1999
Main classification: F04C29
IPC codes: F04C29, F04C18, F25B1, F04C27