SCROLL TYPE COMPRESSOR

Abstract: This invention discloses a lubricating mechanism of a hermetically sealed scroll type compressor in which an inner chamber (61) of a housing (10) is kept at suction pressure. The compressor includes a drive shaft (13) supported by a first plain bearing (14) in an inner block member (11). The drive shaft (13) is operatively linked to an orbiting scroll (30) which orbits within a stationary scroll (20). A rotation preventing device (34) prevents rotation of the orbiting scroll (30). The drive shaft (13) includes an axial bore (81) extending from an open end and terminating within the inner block member (11). A pin (16) extends from the end of the drive shaft (13) to the orbital scroll (30) and is supported in a bushing (17) within an extension of the orbiting scroll (30). A second plain bearing (15) supports the bushing (17). A passage links the axial bore (81) to an opening at the end of the pin (16) facing the orbital scroll (30). A radial bore (82) is provided near the terminal end of the axial bore (81) to link the axial bore (81) to a suction chamber (60) of the compressor. A first helical groove (131) is formed in the exterior surface of the supported portion of the drive shaft (13). The first helical groove (131) is linked to the axial bore (81) through a radial hole (84) formed through the supported portion of the drive shaft (13). A second helical groove (171) is formed in the exterior surface of the bushing. Fluid flows through the radial bore (82) and through the narrow passage to lubricate the rotation preventing device (34). Fluid flows through the first helical groove (131) to lubricate the friction surface between the drive shaft (13) and the first plain bearing (14). Fluid flows through the second helical groove (171) to lubricate the surface between the bushing (17) and the second plain bearing (15).

Description: This invention relates to a scroll type compressor, and more particularly, to a lubricating mechanism for a hermetically sealed scroll type compressor. A hermetically sealed scroll type compressor is disclosed in Japanese Patent Application Publication No. 61-87994 and is shown in Figure 1. A hermetically sealed housing includes inner chamber 1 which is maintained at discharge pressure. The compression mechanism, including interfitting scrolls 2 and 3 and the forward end of the drive mechanism including drive shaft 130, is isolated from inner chamber 1 behind partition 110. Channel 5 links intermediate pocket 6 of the interfitting scrolls 2 and 3 with chamber 7. Refrigerant gas flows through inlet port 850 and is compressed inwardly by scrolls 2 and 3 towards central pocket 700, and flows to discharge chamber 500 through hole 240 and eventually outlet port 860 to an external element of the refrigeration system. Some of the refrigerant gas also flows to inner chamber 1. The intermediate pressure in pocket 6 is maintained in chamber 7 which contains the forward end of the drive mechanism including bearings 141-143. When the compressor operates, lubricating oil mixed with the refrigerant gas, which settles at the bottom of inner chamber 1, flows through channel 8 to lubricate bearings 141-143 of the drive mechanism due to the pressure difference between inner chamber 1, which is maintained at the discharge pressure, and the intermediate pressure. However, it is difficult to utilize the above type lubricating mechanism in a hermetically sealed scroll type compressor in which the inner chamber is maintained at the suction pressure. Since the suction pressure is lower than the discharge pressure and the intermediate pressure, the lubricating fluid will not flow to the drive mechanism in this type of compressor. US-A-4 564 339 discloses a scroll type compressor, the drive shaft of which is arranged vertically. An oil sump is provided at the bottom of the housing and the end of said drive shaft extends into said sump. There is a small lubricating hole formed in the drive shaft extending through the length of said shaft for lubricating the drive shaft bearing and the parts effecting the orbiting motion of one of the scrolls. The refrigerant fluid is led to the scrolls by a separate path. It is an object of this invention to provide a hermetically sealed scroll type compressor in which an inner chamber of the hermetically sealed housing is maintained at suction pressure that is provided with an effective and simplified lubricating mechanism. A compressor according to this invention is indicated in claim 1. A drive mechanism includes a motor supported in the housing. The drive mechanism is operatively connected to the orbiting scroll to effect orbital motion thereof. A rotation preventing device prevents the rotation of the orbiting scroll during orbital motion so that the volume of the fluid pockets changes to compress refrigerant gas in the pockets inwardly from the outermost pocket towards the central pocket. The compressed gas flows out of the central pocket through a channel in the end plate of the fixed scroll and into a discharge chamber. The drive mechanism also includes a drive shaft rotatably supported within an inner block member through a fixed plain bearing. The inner block member is fixedly secured to the housing and divides the suction chamber into a first suction chamber section and a second suction chamber section which includes the rotation preventing device. An axial bore is formed within the drive shaft and is linked to at least one radial bore extending through the drive shaft and leading to the first suction chamber section. One end of the drive shaft includes an open end of the axial bore and is located in close proximity to the inlet of the compressor. The other end of the drive shaft extends into a projecting pin forward of the location where the axial bore terminates within the drive shaft. At least one radial hole is formed through a supported portion of the drive shaft and is linked to the axial bore. At least one helical groove is formed in the exterior surface of the drive shaft and is linked to the radial hole. The terminal end of the axial bore is linked to a narrow offset passage extending through the projecting pin and opening into a gap adjacent the end plate of the orbiting scroll. The projecting pin extends through a bushing located within an annular projection of the orbiting scroll. A second fixed plain bearing is disposed at an exterior peripheral surface of the bushing. The second bearing supports the bushing within the annular projection extending from the end plate of the orbital scroll. At least one helical groove is formed in the exterior surface of the bushing. In operation, the refrigerant gas includes a lubricating fluid which flows from the axial bore toward the radial bores and the offset channel. The fluid lubricates the first plain bearing supporting the drive shaft, the bushing and the second plain bearing, as well as the rotation preventing device located forward of the drive shaft. Further objects, features and other aspects of this invention will be understood from the detailed description of the preferred embodiment of this invention with reference to the annexed drawings. Figure 1 is a vertical longitudinal section of a scroll type compressor in accordance with the prior art. Figure 2 is a vertical longitudinal section of a hermetically sealed scroll type compressor in accordance with this invention. Referring to Figure 2, a hermetically sealed scroll type compressor in accordance with one embodiment of the present invention is shown. For purposes of explanation only, the left side of the Figure will be referenced as the forward end or front and the right side of the Figure will be referenced as the rearward end. The compressor includes hermetically sealed casing 10, fixed and orbiting scrolls 20, 30 and motor 40. Fixed scroll 20 includes circular end plate 21 and spiral element or wrap 22 extending from one end (rearward) surface thereof. Fixed scroll 20 is fixedly disposed within a front end portion of casing 10 by a plurality of screws 26. Circular end plate 21 of fixed scroll 20 partitions an inner chamber of casing 10 into two chambers, for example, discharge chamber 50 and suction chamber 60. O-ring seal 23 is disposed between an inner peripheral surface of casing 10 and an exterior peripheral surface of circular end plate 21 to seal the mating surfaces of casing 10 and circular end plate 21. Orbiting scroll 30 is disposed within suction chamber 60 and includes circular end plate 31 and spiral element or wrap 32 extending from one end (forward) surface of circular end plate 31. Spiral element 22 of fixed scroll 20 and spiral element 32 of orbiting scroll 30 interfit at an angular and radial offset to form a plurality of line contacts which define at least one pair of sealed off fluid pockets 70. Axial annular projection 33 is formed at the rearward end surface of circular end plate 31 opposite spiral element 32. Rotation preventing device 34 is disposed on the outer circumferential surface of annular projection 33 to prevent rotation of orbiting scroll 30 during orbital motion. Inner block member 11 secures stator 41 of motor 40 and is fixedly disposed within suction chamber 60. Inner block member 11 divides suction chamber 60 into first suction chamber section 61 on its rearward side and second suction chamber section 62 on its forward side. Rotation preventing device 34 is located forward of inner block member 11 in second suction chamber section 62. A plurality of communication holes 12 are axially formed through inner block member 11 and link first and second suction chamber sections 61 and 62. Axial annular projection 111 extends from a central region of the rearward end surface of inner block member 11. Drive shaft 13 is rotatably supported within axial annular projection 111 through first fixed plain bearing 14. Drive shaft 13 extends through the center of inner block member 11 and is supported within it through first fixed plain bearing 14. Motor 40 also includes rotor 42 fixedly secured to an exterior peripheral surface of drive shaft 13. Pin member 16 is integral with and axially projects from the forward end surface of drive shaft 13 and is radially offset from the axis of drive shaft 13. Bushing 17 is rotatably disposed within axial annular projection 33 and is supported through second fixed plain bearing 15. Pin member 16 is inserted in hole 18 of bushing 17 which is offset from the center of bushing 17. Gap 170 is located within projection 33, between the end of bushing 17 and circular end plate 31. Gap 172 is located between the exterior surface of bushing 17 and second plain bearing 15. Drive shaft 13 is provided with axial bore 81 and a plurality of radial bores 82. Axial bore 81 extends from an opening at a first (rearward) end of drive shaft 13, that is, the end opposite pin member 16, to a closed end rearward of pin member 16. Narrow offset passage 83 links the forward closed end of axial bore 81 to an open end surface of pin member 16 adjacent orbiting scroll 30. The plurality of radial bores 82 link axial bore 81 near its closed end to first suction chamber section 61 through a plurality of communication holes 112 formed in axial annular projection 111 and corresponding holes 113 in fixed plain bearing 114. Suction gas inlet pipe 85 is inserted through the rear end of casing 10 and faces the opening of axial bore 81. Discharge gas outlet pipe 86 is attached to a side wall of casing 10 and links discharge chamber 50 to an external element. At least one radial hole 84 is linked to axial bore 81 and is formed through drive shaft 13 at a location near the end of annular projection 111. At least one helical groove 131 is formed on the exterior surface of drive shaft 13 and is linked to radial hole 84. Helical groove 171 is formed on the exterior surface of bushing 17 adjacent the inner surface of second plain bearing 15. Helical groove 171 is adjacent gap 172. In operation, stator 41 generates a magnetic field causing rotation of rotor 42, thereby rotating drive shaft 13. This rotation is converted to orbital motion of orbiting scroll 30 through bushing 17; rotational motion is prevented by rotation preventing device 34. Refrigerant gas introduced into suction chamber 60 through suction gas inlet pipe 85 is taken into the outer sealed fluid pockets 70 between fixed scroll 20 and orbiting scroll 30, and moves inwardly towards the center of spiral elements 22, 32 due to the orbital motion of orbiting scroll 30. As the refrigerant moves towards the central pocket, it undergoes a resultant volume reduction and compression, and is discharged to discharge chamber 50 through discharge port 24 and one-way valve 25. Discharge gas in discharge chamber 50 then flows to an external fluid circuit (not shown) through discharge gas outlet pipe 86. The lubricating mechanism of the invention operates as follows. Refrigerant gas including lubricating oil (jointly denoted refrigerant gas, hereinafter) is introduced into suction chamber 60 from suction gas inlet pipe 85, and is largely taken into axial bore 81. A large part of the refrigerant gas flows out of axial bore 81, and into first suction chamber section 61 through radial bores 82 and communication holes 112 and holes 113, and then flows through communication holes 12 into second suction chamber section 62, rearward of rotation preventing device 34. Part of the remainder of the refrigerant gas in axial bore 81 flows through narrow offset passage 83 and into gap 170 between bushing 17 and circular end plate 31. This gas then flows through gap 172 between bushing 17 and second plain bearing 15, and into second suction chamber section 62. Subsequently, the refrigerant gas in second suction chamber section 62 flows through and lubricates rotation preventing device 34, before being taken into sealed fluid pockets 70. Furthermore, a part of the refrigerant gas which is in axial bore 81 flows into helical groove 131 through radial hole 84 to lubricate the friction surface between drive shaft 13 and first plain bearing 14. Similarly, part of the gas which flows through gap 172 between bushing 17 and second plain bearing 15 flows into helical groove 171 to lubricate the friction surface between bushing 17 and second plain bearing 15. Thus, the refrigerant gas effectively lubricates the friction surface between drive shaft 13 and first plain bearing 14, the friction surface between bushing 17 and second plain bearing 15, and rotation preventing device 34. Additionally, some lubricant oil is partially separated from the refrigerant gas and settles beneath orbiting scroll 30, while some of the lubricant oil is taken into sealed fluid pockets 70 as a mist due to orbital motion of orbiting scroll 30 and lubricates the contact surface of the scrolls.

Claims: A scroll type compressor with a hermetically sealed housing (10) the compressor comprising a fixed scroll (20) disposed within said housing (10), said fixed scroll (20) having a first end plate (21) and a first spiral element (22) extending therefrom, said first end plate (21) of said fixed scroll (20) dividing said housing (10) into a discharge chamber (50) and a suction chamber (60) into which said first spiral element (22) extends, an orbiting scroll (30) having a second end plate (31) from which a second spiral element (32) extends, said first and second spiral elements (22, 32) interfitting at an angular and radial offset to form a plurality of line contacts which define at least one pair of sealed off fluid pockets (70), a drive mechanism operatively connected to said orbiting scroll (30) to effect orbital motion of said orbiting scroll (30), a rotation preventing means (34) for preventing the rotation of said orbiting scroll (30) during orbital motion whereby the volume of said fluid pockets (70) changes to compress fluid in said pockets (70), said drive mechanism including a drive shaft (13) rotatably supported within an inner block member (11), said inner block member (11) being fixedly secured to said housing (10), said housing being provided with refrigerant gas inlet and outlet ports (85, 86), characterized by said refrigerant gas inlet port (85) terminating near the end of said drive shaft (13) opposite said scroll (30), said drive shaft (13) having an axial bore (81) extending from an opening at one end of said drive shaft (13) to a closed end near an opposite end of said drive shaft (13) through which the refrigerant gas is flowing, an integral pin member (16) disposed at said opposite end of said drive shaft (13), said pin member (16) being operatively connected to said orbiting scroll (30) through a bushing (17) in which said pin member (16) is located, said bushing (17) being disposed within an axial annular projection (33) extending from said second end plate (31) of said orbiting scroll (30), a narrow passage (83) formed from said closed end of said axial bore (81) to an end surface of said pin member (16) facing said orbiting scroll (30), a first gap (170) formed between said end surface of said pin member (16) and said orbiting scroll (30), a plain bearing (15) disposed between an interior surface of said axial annular projection (33) and an exterior surface of said bushing (17), a helical groove (171) formed in said exterior surface of said bushing (17) and linked to said suction chamber (62) and a second gap (172) formed between said bushing (17) and said plain bearing (15) linking said first gap to said suction chamber (62). The sealed scroll type compressor of claim 1, characterized in that said inner block member (11) comprises a first axial annular projection (111) extending therefrom, and that said first plain bearing (14) is disposed between an interior surface of said first axial annular projection (111) and an exterior surface of said drive shaft (13). The sealed scroll type compressor of claim 1, characterized in that said drive shaft (13) comprises at least one radial bore (82) extending therethrough linking said axial bore (81) near its closed end to said suction chamber (61). The sealed scroll type compressor of claim 1, characterized in that a radial hole (84) is formed near the end of said first axial annular projection (111) and that a first helical groove (131) extends from said radial hole (84) along the entire length of said drive shaft (13) supported in said inner block member (11). The sealed scroll type compressor of claim 1, characterized in that said inner block member (11) divides said suction chamber (60) into a first suction chamber section (61) and a second suction chamber section (62) and that said rotation preventing means (34) is located in said second suction chamber section (62). The sealed scroll type compressor of claim 5, characterized by at least one communicating hole (12) linking said first and second suction chamber sections (61, 62), said communicating hole (12) being formed through said inner block member (11).

Inventors: KIKUCHI, KAZUTO, SHIMIZU, SHIGEMI
Applicants: SANDEN CORPORATION
Application year: 1988
Main classification: F04C29
IPC codes: F04C29, F04C18