HERMETIC SCROLL TYPE COMPRESSOR

Abstract: A hermetic type scroll compressor includes a hermetically sealed compressor housing formed by first (20) and second (30) cup shaped casings. The first casing houses a compression mechanism, while the second casing houses a drive mechanism. The compression mechanism includes a fixed scroll (40) affixed to the first cup shaped casing (20), an orbiting scroll (50) interfitted at an angular and radial offset with the fixed scroll, and a rotation preventing device (70) disposed between the orbiting scroll and the center block. The movement of both the compression and driving mechanisms may be inspected or tested and those mechanisms may be readily disassembled so that component parts thereof may be adjusted or replaced before hermeti­ cally securing the first casing to the second casing. Furthermore, each casing is provided with a center block (60, 80) forming, in part, an alignment mech­ anism for aligning the drive mechanism drive shaft with the orbiting scroll of the compression mechanism.

Description: The present invention relates to a scroll type compressor and more particularly, to a motor driven scroll compressor having the compression and driving mechanisms within a hermetically sealed housing. Scroll type fluid displacement apparatus are well known in the prior art. For example, US-A- 801,182 discloses such an apparatus which included two scrolls, each having a circular end plate and a spiroidal or involute spiral element. The scrolls are maintained angularly and radially offset so that both spiral elements interfit to form a plurality of line contacts between their spiral curved surfaces to thereby seal off and define at least one pair of fluid pockets. The relative orbital motion of the two scrolls shifts the line contacts along the spiral curved surfaces and, as a result, the volume of the fluid pockets increases of decreases, dependent on the direction of the orbital motion. Thus, a scroll type fluid displacement apparatus may be used to compress, expand or pump fluids. Furthermore, US-A- 4,560,330 for example, discloses a hermetic scroll compressor which includes a compression mechanism having a fixed scroll, an orbiting scroll associated with a rotation preventing device, and driving mechanism thereof in one sealed container. In this hermetic type scroll compressor, the essentially inseparable container is hermetically sealed, for example, by welding, so that leakage of refrigerant from the container is prevented. While the above mentioned hermetically sealed scroll compressor prevent leakage of refrigerant from the container, it can be disassembled only by destructively opening the sealed container to, for example, repair, adjust or exchange internal parts. Furthermore, it is virtually impossible to dynamically test the compression and drive mechanisms before assembling the compressor components into the sealed container. Therefore, compressors found to be functionally defective after assembly thereof, often become scrap in view of the repair factors which may render repair cost-ineffective. In accordance with the present invention, a scroll type compressor with a hermetically sealed housing, comprises a fixed scroll fixedly disposed within the housing and having an end plate from which a first wrap extends into the interior of the housing, an orbiting scroll having an end plate from which a second wrap extends, the first and second wraps 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, a driving mechanism including a motor supported in the housing the driving mechanism being operatively connected to the orbiting scroll to effect the orbital motion of the orbiting scroll, rotation preventing means for preventing the rotation of the orbiting scroll during orbital motion thereof, whereby the volume of the fluid pockets changes during the orbital motion to compress the fluid in the pockets; wherein the housing includes a first cup shaped casing and a second cup shaped casing, the first cup shaped casing housing the fixed scroll, the orbiting scroll and the rotation preventing means, the second cup shaped casing housing the driving mechanism which further includes a drive shaft, the first and second cup shaped casings being fused to form the hermetically sealed housing; a first centre block being disposed within the first cup shaped casing, the first centre block having a front surface and a rear surface, the rear surface being connected to a portion of the rotation preventing means; a second centre block being disposed within the second cup shaped casing and rotatably supporting one end of the drive shaft, the second centre block having a front surface facing the first centre block front surface; and alignment means formed on engaging portions of the facing surfaces of the first and second centre blocks for aligning the drive shaft with the orbiting scroll. Such a compressor may be manufactured by assembling the first casing and the second casing separately so that the components in each casing may be disassembled, reassembled and inspected independently before permanently securing the first and second casings to form a hermetically sealed housing. The alignment means may be used for aligning a dynamic testing device with either the compression mechanism or drive mechanism so that either mechanism may be easily aligned with the testing device and the time for testing procedures may be reduced. The compressor construction of the present invention incorporates the separate compression and drive mechanisms and casings therefor as described in EP-A-0283045 which discloses a hermetically sealed scroll compressor wherein the compressor housing includes two releasably secured casings to facilitate disassembly and reassembly of the compressor. EP-A-0283045 has a priority date (20.03.87) earlier than this patent but was published later (Art 54(3) (EPC) and its subject matter (see in particular Fig. 2) comprises all the features of the invention except in that here the cups are bolted together and not fused. Even though, the releasable construction improves cost efficiencies regarding inspection and repair, after the compressor has been assembled, the releasable seal may not sufficiently prevent leakage of refrigerant from the housing. The casings of the present invention are fused to form the hermetically sealed housing and to more effectively prevent the aforementioned leakage. Even though the fusion joint prevents effective disassembly and thus repair of the internal components after the compressor has been assembled, the compressor and drive mechanisms retain their individual inspectability, testability and repairability during manufacture. The compressor may further include a rear support block disposed within the second cup shaped casing. The rear support block supports the other end of the drive shaft and is releasably secured to the second center block. In the accompanying drawing : Figure 1 is a vertical longitudinal sectional view of a hermetic type scroll compressor in accordance with a preferred embodiment of this invention. Compressor 10 includes compressor housing 400 which is formed by first cup shaped casing or shell 20 and second cup chaped casing of shell 30. First casing 20 houses the compression mechanism, while second casing 30 houses the driving mechanism. Casings 20 and 30 are joined or fused together to form compressor housing 400 and to hermetically seal the compression mechanism and driving mechanism therefor. The compression mechanism comprises fixed scroll 40 which includes circular end plate 41 and wrap or spiral element 42 affixed to or extending from one end surface of end plate 41. Fixed scroll 40 is fixedly secured to first cup shaped casing 20 by fastener or screws 21, so that fixed scroll 400 is fixedly positioned within an inner chamber of first casing 20. Screws 21 are screwed into inner axial projection 22, projecting from an inner bottom surface of casing 20, through holes 43 formed in end plate 41. Anti-wear plate 44 is disposed on one end surface of end plate 41 and covers an opening to each hole 43. O-ring seal 23 is disposed between an outer peripheral surface of circular end plate 41 and an inner peripheral surface of first cup shaped casing 20 to seal a mating surface therbetween. Accordingly, circular end plate 41 partitions the inner chamber of first cup shaped casing 20 into two chambers, i.e., front chamber 18 and rear chamber 19. With reference to Figure 1, orbiting scroll 20 is disposed to the rear or right side of first center block 80 which includes central bore 61 and flange 60. Orbiting scroll 50 includes circular end plate 61 and wrap or spiral element 52 affixed to or extending from one end surface of circular end plate 51. Annular projection 53 is formed opposite the surface of circular end plate 51 from which spiral element 52 extends. Bearing 54 is disposed within an inner peripheral wall of annular projection 53. Rotation preventing/thrust bearing device 70 is placed between and connected to the rear end surface of first center block 60 and the end surface of circular end plate 51. Rotation preventing/thrust bearing device 70 includes first ring 71 attached to the rear end surface of first center block 60, second ring 72 attached on the end surface of circular end plate 51, and a plurality of bearing elements, such as balls 73, placed between pockets 71a and 72a formed by rings 71 and 72. The rotation of orbiting scroll 50 is prevented by the interaction of balls 73 with rings 71 and 72. Also, the axial thrust load from orbiting scroll 50 is supported on first center block 60 through balls 73. Therefore, while orbiting scroll 30 orbits, the rotation of orbiting scroll 50 is prevented by rotation preventing/thrust bearing device 70. Spiral element 52 of orbiting scroll 50 interfits spiral element 42 of fixed scroll 40 at an angular offset of 180° and at a predetermined radial offset. Spiral elements 52 and 42 define at least one pair of sealed off fluid pockets between their interfitting surfaces. Once both spiral elements 52 and 42 are placed in an interfitting position, first center block 80 is fixed within the inner chamber of first cup shaped casing 20 by securing flange 62 to a plurality of inner radial projections 24 with screws 63. Projections 24 radially extend from the inner surface or inner wall of casing 20 and may be formed therewith or secured thereto. After assembly, first cup shaped casing 20 houses the compression mechanism and forms compression mechanism section 200 therewith. Compression mechanism section 200 comprises first center block 60 and the construction to the right thereof as shown in Figure 1. More specifically, compression mechanism section 200 includes first cup shaped casing 20 having first center block 60, fixed scroll 40, orbiting scroll 50 and rotation preventing/thrust bearing device 70 therein. Second center block 80 fits firmly within second cup shaped casing 30 and is positioned against ridge 31 which is formed in an inner wall of second casing 30. Second center block 80 rotatably supports one end of drive shaft 11 in bore 81 of second center block 80 through bearing 82. Bushing 111 is attached to the one end of drive shaft 11 at a radial offset through pin member 112. The other end of drive shaft 11 is rotatably supported by rear support block 90 through bearing 91. Stator 101 of motor 100 is held between and supported by second center block 80 and rear support block 80 which include annular support grooves 85 and 92 formed therein for supporting the motor. Motor 100 also includes rotor 102 which rotates with shaft 11. Rear support block 90 is releasably secured to second center block 80 by through-bolts 93 which may be threaded. These releasable securing mechanisms permit the driving mechanism, which comprises rear support block 90, motor 100 and second center block 80, to be easily assembled or disassembled prior to insertion into second cup shaped casing 30. Wires 110 extend from stator 101 and pass through hermetic seal base 120 for connection with an electrical power source (not shown). Hermetic seal base 120 is hermetically secured to second cup shaped casing 30 about hole 32 which is formed at the side surface of second cup shaped casing 30. For example, base 120 may be welded or brazed to casing 30 to provide the hermetic seal therebetween. After assembly, second cup shaped casing 30 houses the driving mechanism and forms driving mechanism section 300 therewith. Driving mechanism section 300 comprises second center block 80 and the construction to the left thereof as shown in Figure 1. More specifically, driving mechanism section 300 includes second cup shaped casing 30 having second center block 80, motor 100 including shaft 11, and rear bearing block 90 therein. Once compression mechanism section 200 and driving mechanism section 300 have been assembled, these sections may be inspected and then joined to form compressor 10. When sections 200 and 300 are fitted together, the facing surfaces of first center block 60 and second center block 80 form an alignment mechanism for aligning drive shaft 11 with orbiting scroll 50. First center block 60 includes annular portion 65 having annular recess 64 formed in an inner wall thereof. With reference to Figure 1, recess 64 is formed at the front or left end of the inner wall which forms bore 61. Recess 64 also includes abutment surface 67 which is substantially normal to the center lines of shaft 11 when sections 200 and 300 are joined. Front end surface or guide surfaces 68 of first center block 60 extends radially outwardly from annular recess 64. Surface 66 is preferably frustoconical. However, surface 66 may be dish-shaped with a concave curvature or it may have other suitable curvatures, such as a convex curvature, for slidingly guiding second center block 80 therealong and toward annular recess 64. Second center block 80 includes annular projection 83 having an outer diameter slightly smaller than the diameter of annular recess 64, so that projection 83 may securely interfit with recess 64 when the first and second center blocks are brought into engagement. As can be seen in Figure 1, abutment surface 67 prevents annular projection 83, which is formed at the front or right end of second block 80, from penetrating within first cup shaped casing 20 beyond first center block 60. The front surface of second block 80 includes portion 84 which extends radially outwardly from annular projection 83. Portion 84 is shown as being frustoconical and as having a slope less than the slope of surface 66 with respect to the center line of shaft 11. The difference in slope provides a space between surfaces 66 and 84 and prevents excessive interference therebetween when joining sections 200 and 300. However, portion 84 may have other curvatures, such as convex or concave curvatures, which would provide such a space between surfaces 66 and 84. Therefore, when sections 200 and 300 are being joined to form compressor 10, front end surface 66 may guide or center annular projection 83 into annular recess 64. Projection 83 and recess 64 further form an alignment mechanism for aligning drive shaft 11 with orbiting scroll 50. Accordingly, bushing 111 is inserted into annular projection 53 of circular end plate 51 so as to attach drive shaft 11 to orbiting scroll 50 at a radial offset. Orbiting scroll 50 is rotatably supported by bushing 111 through bearing 54 disposed within the inner peripheral wall of annular projection 53. Both open ends of first and second cup shaped casings 20 and 30 are closed as annular projection 83 and recess 64 are fitted. Then sections 200 and 300 are hermetically joined by a suitable means, such as welding or brazing, to form compressor 10 with hermetically sealed compressor housing 400. During manufacture, a static or dynamic testing device (not shown) may be used to inspect compression mechanism section 200 or driving mechanism section 300 before joining those sections to form compressor housing 400. For such testing, projection 83 or recess 64 also may form an alignment mechanism for aligning the testing device with the driving or compression mechanism sections. For example, a testing device for testing compression mechanism section 200 may be provided with a projection similar to projection 83 for engagement with annular recess 64 of first center block 60. Once the testing device is interfitted with compression mechanism section 200, section 200 may be statically or dynamically inspected. In a similar manner, driving mechanism section 300 may be inspected or tested. The operation of compressor 10 will be described hereafter. Once motor 100 is energized, stator 101 generates a magnetic field and rotor 102 rotates, thereby rotating drive shaft 11. This rotational motion is transferred to orbital motion through bushing 111. Therefore, orbiting scroll 50 orbits, but rotation or orbiting scroll 50 is prevented due to rotation prevention/thrust bearing device 70. Refrigerant gas is introduced into inner chamber 17 of second cup shaped casing 30 through inlet port 301 which is formed at the side wall of second cup shaped casing 30, and flows through front chamber 18 of first cup shaped casing 20 through bearing 82 and then through rotation preventing/thrust bearing device 70. The referigerant gas in front chamber 18 is taken into the sealed fluid pockets between fixed scroll 40 and orbiting scroll 50. Then refrigerant is forced toward the center of the spiral wraps during the orbital motion of orbiting scroll 50 with resultant volume reduction and compression. The compressed refrigerant is discharged into rear chamber 19 through hole 45 and one-way valve 46. Finally, the discharged refrigerant in rear chamber 19 flows to an external fluid circuit (not shown) through outlet port 201.

Claims: 1. A scroll type compressor with a hermetically seated housing, (400) the compressor comprising a fixed scroll (40) fixedly disposed within the housing (400) and having an end plate from (41) from which a first wrap (42) extends into the interior of the housing, (400) an orbiting scroll (50) having an end plate (51) from which a second wrap (52) extends, the first and second wraps (42,52) interfitting at an angular and radial offset to form a pluratity of tine contacts which define at least one pair of seated off fluid pockets, a driving mechanism (300) including a motor (100) supported in the housing (400) the driving mechanism (300) being operatively connected to the orbiting scroll (50) to effect the orbital motion of the orbiting scroll (50), rotation preventing means (70) for preventing the rotation of the orbiting scroll (50) during orbital motion thereof, whereby the volume of the fluid pockets changes during the orbital motion to compress the fluid in the pockets; wherein the housing (400) includes a first cup shaped casing (20) and a second cup shaped casing (30), the first cup shaped casing (20) housing the fixed scroll (40), the orbiting scroll (50) and the rotation preventing means (70), the second cup shaped casing (30) housing the driving mechanism (300) which further includes a drive shaft (11), the first and second cup shaped casings (20,30) being fused to form the hermetically seated housing; a first centre block (60) being disposed within the first cup shaped casing (20), the first centre block (60) having a front surface and a rear surface, the rear surface being connected to a portion of the rotation preventing means (70); a second centre block (80) being disposed within the second cup shaped casing (30) and rotatably supporting one end of the drive shaft (11), the second centre block (80) having a front surface facing the first centre block (60) front surface; and alignment means formed on engaging portions of the facing surfaces of the first and second centre blocks (60,80) for aligning the drive shaft (11) with the orbiting scroll (50). 2. A compressor according to claim 1, wherein the alignment means comprises an annular recess (64) formed an inner portion of the first centre block (60) and an annular projection (83) formed on the second centre block (80). 3. A compressor according to claim 2, wherein the annular recess (64) includes an abutment surface (67) for preventing the annular projection (83) from penetrating beyond the first centre block (60) within the first cup shaped casing (20) the abutment surface (67) being substantially normal to the centre tine of the drive shaft (11). 4. A compressor according to claim 2 or claim 3, wherein the alignment means further comprises a guide surface (66) formed on the front surface of the first centre block (60) for guiding the second centre block (80) therealong and toward the annular recess (64), the guide surface (66) extending radially outwardly from the annular recess (64). 5. A compressor according to claim 4, wherein the guide surface (66) is frustoconical. 6. A compressor according to claim 5, wherein the front surface of the second centre block (80) comprises a frustoconical portion extending radially outwardly from the annular projection (83). 7. A compressor according to any one of the preceding claims, wherein the first centre block (60) is releasably secured to the first cup shaped casing (20). 8. A compressor according to claim 7, wherein the first cup shaped casing (20) includes at least one projection (24) extending radially inwardly from an inner wall of the first cup shaped casing (20), the first centre block (60) being releasably secured to the at least one projection. 9. A compressor according to any of the preceding claims, wherein the first (60) and second centre blocks (80) are entirety disposed within the hermetically sealed housing (400). 10. A compressor according to any of the preceding claims, wherein the second cup shaped casing (30) further houses a rear support block (90) which rotatable supports the other end of the drive shaft (11), the rear support block (90) being releasably secured to the second centre block (80). 11. A compressor according to claim 10, wherein the motor (100) is held between and supported by the second centre block (80) and rear support block (90). 12. A compressor according to claim 10 or claim 11, wherein the rear support block (90) is releasably secured to the centre block by through-bolts (93). 13. A compressor according to any one of the preceding claims, wherein the first and second cup shaped casings (20,30) include are welded together to form the hermetically seated housing. 14. A compressor according to any one of claims 1 to 12, wherein the first and second cup shaped casings (20,30) are brazed together to form the hermetically seated housing.

Inventors: KIKUCHI, KAZUTO, SHIMIZU, SHIGEMI 425 HIGASHI-ARAI, TERAUCHI, KIYOSHI
Applicants: SANDEN CORPORATION
Application year: 1989
Main classification: F04C23
IPC codes: F04C23, F01C17, F04C18