SCROLL TYPE COMPRESSOR WITH LUBRICATING SYSTEM

Abstract: A lubricating system for a scroll type compressor is described. The compressor unit includes a housing having a front end plate (11) and a cup shaped casing (12). A rotation preventing mechanism for an orbiting scroll is disposed between the inner end surface of the front end plate and a circular end plate of the orbiting scroll. A fluid inlet port (36) is formed on the cup shaped casing and placed for opposing the rotation preventing mechanism.

Description: SCROLL TYPE COMPRESSOR WITH LUBRICATING SYSTEM This application is a divisional application from our copending European patent application No. 83305951.2 filed on September 30, 1983. This invention relatos to fluid displacement apparatus, and more particularly, to a scroll type fluid compressor. Scroll type fluid displacement apparatus are well known in the prior art. For example, U.S. Patent No. 801,182 (Creux) discloses a scroll type fluid displacement apparatus including two scroll members each having a circular end plate and a spiroidal or involute spiral element. These scroll members are maintained angularly and radially offset so that the spiral elements interfit to make a plurality of line contacts between their spiral curved surfaces, thereby to seal off and define at least one pair of fluid pockets. The relative orbital motion of the two scroll members shifts the line contacts along the spiral curved surfaces and, therefore, the fluid pockets change in volume. The volume of the fluid pockets increases or decreases dependent on the direction of the orbital motion. Therefore, scroll type fluid displacement apparatus are applicable to compress, expand or pump fluids. EP-A-0.077.214 was filed prior to the date of filing of the present application but published after that date. EP-A-0.077.214 discloses a scroll type compressor including a housing which comprises a front end plate and a cup shaped casing. Fluid inlet and outlet ports are formed in the housing. A fixed scroll having a fixed scroll end plate from which a first wrap extends is fixedly disposed within the housing. An orbiting has an orbiting scroll end plate from which a second wrap extends. The first and second wraps interfit at an angular and radial offset to make a plurality of line contacts to define at least one pair of sealed off fluid pockets. A driving mechanism is operatively connected with the orbiting scroll to effect orbiting motion of the orbiting scroll whilst preventing orbital motion of that scroll, thus changing the volume of the fluid pockets. Scroll type fluid displacement apparatus are particularly well-suited for use as a refrigerant compressor in an automobile air conditioner. Generally, it is desirable that the refrigerant compressor for an automobile air conditioner be compact in size and light in weight, since the compressor is placed in the engine compartment of an automobile. However, the refrigerant compressor is generally coupled to an electromagnetic clutch for transmitting the output of an engine to the drive shaft of the compressor. The weight of the electromagnetic clutch therefore increases the total weight of a compressor unit. It is an object of this invention to provide a scroll type compressor wherein moving parts, in particular a shaft seal portion, are efficiently lubricated and cooled. According to the present invention there is provided a scroll type compressor including a housing comprising a front end plate and a cup shaped casing, a fixed scroll fixedly disposed within said housing and having a fixed scroll end plate from which a first wrap extends, an orbiting scroll having an orbiting scroll end plate from which a second wrap extends, said first and second wraps interfitting at an angular and radial offset to make a plurality of line contacts to define at least one pair of sealed off fluid pockets, a driving mechanism operatively connected with said orbiting scroll to effect the orbital motion of said orbiting scroll while preventing the rotation of said orbiting scroll, and thus changing the volume of said fluid pockets due to the orbital motion of said orbiting scroll, a fluid inlet port formed in said cup shaped casing radially outwardly of said orbiting scroll for introducing an oil misted gas into the interior of the housing, said fluid inlet port having a step portion projecting radially inwardly from an inner wall of said fluid inlet port; a first lubricant passageway having one end opening to the inner wall of said fluid inlet port adjacent to said step portion; and a second lubricant passageway formed through said front end plate, said second lubricant passageway connecting said first lubricant passageway and a shaft seal cavity formed in said front end plate so that lubricant separates from incoming gas to be compressed on said step portion and passes thereform to said seal cavity through said first and second lubricant passageways. The step portion may have a flange portion formed on it generally perpendicular to the radially inner end of said step portion. The invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a vertical sectional view of a main part of a compressor according to one embodiment of this invention. Figure 2 is a vertical sectional view illustrating a prior art compressor. Prior to the description of the embodiment of this invention, a known compressor of a scroll type will be described with reference to Figure 2. Referring to Figure 2, a refrigerant compressor unit includes a compressor housing 10 comprising a front end plate 11 and a cup shaped casing 12 which is attached to one side surface of front end plate 11. An opening 111 is formed in the center of front end plate 11 for penetrating or passage of a drive shaft 13. An annular projection 112 concentric with opening 111 is formed on the inside face of front end plate 11 and projects towards cup shaped casing 12. An outer peripheral surface of an annular projection 112 contacts an inner wall surface of cup shaped casing 12. Cup shaped casing 12 is fixed to front end plate 11 by a fastening means, for example, bolts-nuts (not shown). The open portion of cup shaped casing 12 is thereby covered and closed by front end plate 11. An O-ring member 14 is placed between front end plate 11 and the open portion of cup shaped casing 12, to thereby secure a seal between the fitting or mating surfaces of front end plate 11 and cup shaped casing 12. Front end plate 11 has an annular sleeve portion 17 projecting outwardly from the front or outside surface thereof. Sleeve 17 surrounds drive shaft 13 and defines a shaft seal cavity. In the embodiment shown in Figure 2, sleeve portion 17 is formed separately from front end plate 11. Therefore, sleeve portion 17 is fixed to front end surface of front end plate 11 by a suitable fastening means, for example, screws (not shown). Alternatively, the sleeve portion 17 may be formed integral with front end plate 11. Drive shaft 13 is rotatably supported by sleeve portion 17 through a bearing 19 disposed within the front end portion of sleeve portion 17. Drive shaft 13 is formed with a disk rotor 131 at its inner end portion, which is rotatably supported by front end plate 11 through a bearing 16 disposed within opening 111 of front end plate 11. A shaft seal assembly 20 is assembled on drive shaft 13 within the shaft seal cavity of front end plate 11. Drive shaft 13 is coupled to an electromagnetic clutch (not shown) which may be disposed on the outer peripheral portion of sleeve portion 17. Thus, drive shaft 13 is driven by an external drive power source, for example, a motor of a vehicle, through a rotation force transmitting means such as sn electromagnetic clutch. A fixed scroll 25, an orbiting scroll 26, a driving mechanism for orbiting scroll 26 and a rotation preventing/thrust bearing means 37 for orbiting scroll 26 are disposed in the inner chamber of cup shaped casing 12. The inner chamber is formed between the inner wall of cup shaped casing 12 and front end plate 11. Fixed scroll 25 includes a circular end plate 251 and a wrap or spiral element 252 affixed to or extending from one major side surface of circular plate 251. A bottom plate 122 of cup shaped casing 12 is formed with a plurality of legs 253 axially projecting from its inner end surface, as shown in Figure 2. An axial end surface of each leg 253 is fitted against the other major side surface of circular end plate 251. Fixed scroll 25 is fixed by a plurality of by screws 27 each of which screw into circular end plate 251 from the outside of bottom plate portion 122 through leg 253. A first sealing member 28 is disposed between the end surface of each leg 253 and the inner surface of bottom plate portion 122, to thereby prevent fluid leakage along screws 27. A groove 256 is formed on the outer peripheral surface of circular plate 251 and a second seal ring member 29 is disposed therein to form a seal between the inner surface of cup shaped portion 12 and the outer peripheral surface of circular plate 251. Thus, the inner chamber of cup shaped portion 12 is partitioned into two chambers by circular plate 251; a rear or discharge chamber 30, in which legs 253 are disposed, and a front or suction chamber 31, in which spiral element 251 of fixed scroll 25 is disposed. Cup chaped casing 12 is provided with a fluid inlet port 35 and a fluid outlet port 36, which respectively are connected to the front and rear chambers 31, 30. A hole or discharge port 254 is formed through the circular plate 251.at a position near to the center of spiral element 252. Discharge port 254 connects the fluid pocket formed in the center of the interfitting spiral element and rear chamber 30. Orbiting scroll 26 is disposed in front chamberer 31. orbiting scroll member 26 also comprises a circular end plate 261 and a wrap or spiral element 262 affixed to or extending from one side surface of circular end plate 261. Spiral element 262 and spiral element 252 inter-fit at angular offset of 180° and a predetermined radial offset. A pair of fluid pockets are thereby defined between spiral elements 252, 262. Orbiting scroll 26 is connected to the drive mechanism and to the rotation preventing/thrust bearing mechanism. These last two mechanisms effect orbital motion of the orbiting scroll member 26 by rotation of drive shaft 13, to thereby compress fluid passing through the compressor unit. The driving mechanism of orbiting scroll 26 will be described. Drive shaft 13, which is rotatably supported by sleeve portion 17 through ball bearing 19, is formed with disk-rotor 131. Disk rotor 131 is rotatably supported by front end plate 11 through ball bearing 16 disposed within opening 111 of front end plate 11. A crank pin or drive pin 15 projects axially inwardly from an end surface of disk rotor 131 and is radially offset from the center of drive shaft 13. Circular plate 261 of orbiting scroll 26 is provided with a tubular boss 263 projecting axially, outwardly from the end surface opposite to the side from which spiral element 262 extends. A discoid or short axial bushing 33 is fitted into boss 263, and is rotatably supported therein by a bearing, such as a needly bearing 34. Bushing 33 has a balance weight 331 which is shaped as a portion of a disk or ring and extends radially from bushing 33 along a front surface thereof. An eccentric hole is formed in bushing 33 radially offset from the center of bushing 33. Drive pin 15 is fitted into the eccentrically disposed hole 332, within which a bearing may be inserted. Bushing 33 is therefore driven by the revolution of drive pin 15 and permitted to rotate by needle bearing 34. The spiral element of orbiting scroll 26 is thus pushed against the spiral element of fixed scroll 25 due to the moment created between the driving point and the reaction force acting point of the pressurized gas. The rotation preventing/thrust bearing device 37 will be explained. Rotation preventing/thrust bearing device 37 is placed between the inner end surface of front end plate 11 and the end surface of circular end plate 261 of orbiting scroll 26 which faces the inner end surface of front end plate 11. Rotation preventing/thrust bearing device 37 includes a fixed ring 371 which is fastened against the inner end surface of front end plate 11, an orbiting ring 372 which is fastened against the end surface of circular end plate 261, and bearing elements, such as a plurality of spherical balls 373. As shown in Figures, both ring 371 and 372 are formed by separate plate elements 371a and 372a, and ring elements 371b and 372b which have the plurality of pairs of holes 374 and 375. The elements of each ring are respectively fixed by suitable fastening means. Alternatively, the plate and ring elements may be formed integral with one another. In operation, the rotation of orbiting scroll 26 is prevented by balls 373, which interact with the edges of holes 374 and 375 to prevent rotation. Also, these balls 373 carry the axial thrust load from orbiting scroll 26. Thus, orbiting scroll 26 orbits while maintaining its angular orientation with respect to fixed scroll 25. The cup-shaped casing 12 is formed with a fluid inlet port 35 and this fluid inlet port 35 is located in the casing 12 at a location radially outwardly of and at the same axial location as a portion of the rotation preventing/thrust bearing device 37. Therefore, the refrigerant gas which is introduced into the suction chamber 31 through the fluid inlet port 35 strikes against a part of the rotation preventing/thrust bearing device 37. The lubricating oil, which exists within the refrigerant gas as an oil mist, is separated from the suction gas. After separating, the oil adheres to the balls and to the surfaces of the orbiting and fixed rings which are contacted by the rolling surfaces of the balls, and lubricates the rolling surfaces. The suction gas also cools and lubricates parts of the bearing portion disposed within cup-shaped casing 12. Now, an embodiment of the present invention will be described with reference to Figure 1. The compressor shown in Figure 1 is similar to the known compressor of Figure 2 except for its lubricating system. Therefore, only a part of the compressor, including the lubricating system, is shown. The remaining portion of the compressor is omitted for the purpose of simplification of the drawings. Similar parts are represented by the same reference numerals as in Figure 2 except for parts of the lubricating system. Referring to Figure 2, a fluid inlet port 2 of the lubricating system is formed in cup shaped housing 12 and extends radially and outwardly of orbiting scroll 26 in suction chamber 31. During operation of the compressor, an oil misted refrigerant gas is introduced through fluid inlet port 2 into suction chamber 31. The interior of sleeve portion 17 is connected to an opening 111 in front end plate 11 to form a shaft seal cavity 6. In the shaft seal cavity 6, a shaft seal assembly 20 is mounted on drive shaft 13. A lubricating system for the compressor will now be described. A step portion 2a is formed in the fluid inlet port 2. Step portion 2a projects radially inwardly from an inner wall of fluid inlet port 2. A flange 2b is formed along the inner end portion of step portion 2a and is generally perpendicular to step portion 2a to accumulate and separate oil at step portion 2a. Flange 2b projects radially outward from step portion 2a as viewed with respect to the rotational axis of shaft 13. Cup shaped casing 12 is formed with a first oil passageway 4 one end of which opens at the inner wall of fluid inlet port 2. First oil passageway 4 is connected with a second oil passageway 5 which opens at the inner wall of shaft seal cavity 6. The shaft seal cavity in which shaft seal assembly 20 is disposed is thus connected with fluid inlet port 2 through oil passageways 4 and 5. In this construction, during the operation of the compressor, the refrigerant gas is introduced into suction chamber 31 through inlet port 2. The oil mist suction gas strikes against step portion 2aq. The oil included with the suction gas is separated therefore and accumulates on step portion 2a. Following the flow of suction gas, the accumulated oil flows into first oil passageway 4, and then flows out to the shaft seal cavity 6 of front end plate 11 through second oil passageway 5. The oil which flows into the shaft seal cavity lubricates and cools the shaft seal assembly 20 and returns to the suction chamber 31 through bearing 16 while lubricating bearing 16.

Claims: A scroll type compressor including a housing (10) comprising a front end plate (11) and a cup shaped casing (12), a fixed scroll (25) fixedly disposed within said housing (10) and having a fixed scroll end plate (251) from which a first wrap (252) extends, an orbiting scroll (26) having an orbiting scroll end plate (261) from which a second wrap (262) extends, said first and second wraps (252, 262) interfitting at an angular and radial offset to make a plurality of line contacts to define at least one pair of sealed off fluid pockets, a driving mechanism operatively connected with said orbiting scroll (26) to effect the orbital motion of said orbiting scroll (26) while preventing the rotation of said orbiting scroll (26), and thus changing the volume of said fluid pockets due to the orbital motion of said orbiting scroll (26), a fluid inlet port (2) formed in said cup shaped casing (12) radially outwardly of said orbiting scroll for introducing an oil misted gas into the interior of the housing (10), said fluid inlet port (2) having a step portion (2a) projecting radially inwardly from an inner wall of said fluid inlet port (2); a first lubricant passageway (4) having one end opening to the inner wall of said fluid inlet port (2) adjacent to said step portion (2a); and a second lubricant passageway (5) formed through said front end plate (11), said second lubricant passageway (5) connecting said first lubricant passageway (4) and a shaft seal cavity formed in said front end plate (11) so that lubricant separates from incoming gas to be compressed on said step portion (2a) and passes thereform to said seal cavity through said first and second lubricant passageways (4,5). The scroll type compressor of claim 1 characterised in that said step portion (2a) has flange (2b) formed on it and generally perpendicular to the radially inner end portion of said step portion (2a). The scroll compressor according to claim 1 or 2, characterised by lubricant passageway means for conveying lubricant from said shaft seal cavity to an intake chamber of the scroll type compressor.

Inventors: TERAUCHI, KIYOSHI
Applicants: SANDEN CORPORATION
Application year: 1983
Main classification: F04C29
IPC codes: F04C29