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

[0001] This invention relates to a fluid displacement apparatus, and more particularly, to a scroll type fluid compressor.

[0002] 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 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.

[0003] As described in U.S. Patent No. 3,874,827, 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 is placed in the engine com­partment of an automobile. However, the refrigerant compressor is generally coupled to a electromagnetic clutch for transmitting the output of an engine to the drive shaft of the compressor. The weight of the electromagnetic clutch is therefore added to the weight of the compressor to thereby increase the total weight of compressor unit.

[0004] In the scroll type compressor, from the nature of these constructions, the orbiting scroll is supported for cantilever and driving mechanism for oribiting scroll is concentrated upon the rear end of the orbiting scroll. Furthermore, the fluid inlet port which is formed in the housing is placed on the outer peripheral portion of spiral element or rear end portion of fixed scroll to introduce the fluid into the interior of the housing without pressure loss of compress fluid.

[0005] However, in above construction of the compressor, lubri­cation or cool to the bearing portion which is consisted of supporting construction or driving mechanism for the orbiting scroll can not sufficient, so that separation at high contact pressure surface portion of the bearing portion may be occurred.

[0006] In order to avoid these disadvantages, a prior compressor, disclosed in EP-A-0 133 625, has a fluid inlet port formed in its housing and located adjacent an outer peripheral portion of the spiral element of the orbiting scroll member. A step portion is formed in the fluid inlet port. This step portion projects radially inwardly from an inner wall of fluid inlet port. The housing is formed with a first oil passage way, one end of which opens at the inner wall of fluid inlet port, and a second oil passage way, which extends from the first passage way to a shaft seal cavity including a shaft seal assembly. In operation, refrigerant gas is introduced into the interior of the housing through inlet port. The oil mist in the suction gas strikes against the step portion in the inlet port and the oil is separated out. Following the flow of suction gas, the separated oil flows into the first oil passageway and then flows on to the shaft seal cavity through the second oil passage way. The oil which flows into the shaft seal cavity lubricates and cools the shaft seal assembly and returns to the interior of the housing while lubricating the bearing portions.

[0007] In this mechanism, the step portion for separating and accumulating oil must be formed in the fluid inlet port and the oil passageway extending between the shaft seal cavity and the fluid inlet port must be formed in the housing, with a resultant increase in the wall thickness of the housing. Therefore, the construction and forming of the housing is complicated and the diameter of the housing is increased.

[0008] EP-A-O 077 214, which falls within the terms of Article 54(3) EPC, discloses a scroll type compressor having orbiting and fixed scroll members disposed within a housing formed of a front end plate and a cup-shaped casing. A rotation preventing/thrust bearing device is disposed between the front end plate and the orbiting scroll member. A fluid inlet port is formed in the cup-shaped casing, close to the orbiting scroll member and the rotation preventing/­thrust bearing device. The inlet port extends from a first axial location, which is between opposed surfaces of a peripheral portion of an end plate of the orbiting scroll member, to a second axial location, which is between two plate elements together forming an orbiting ring of the rotation preventing/thrust bearing device and each secured to the end plate of the orbiting scroll member.

[0009] It is a primary object of this invention to provide an improved scroll type compressor which is compact in size and light in weight.

[0010] It is another object of this invention to provide a scroll type compressor which is simple in construction and configuration, and easy to assemble.

[0011] It is still another object of this invention to provide a scroll type compressor wherein moving parts, in particular a shaft seal portion, are efficiency lubricated and cooled.

[0012] 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 first circular end plate from which a first wrap extends, an orbiting scroll having a second circular 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 orbital motion of said orbiting scroll while rotation of said orbiting scroll is prevented by a rotation preventing/thrust bearing device, and thus changing the volume of said fluid pockets due to the orbital motion of said orbiting scroll, said rotation preventing/thrust bearing device being located between an inner end surface of said front end plate and an end surface of said second circular end plate of said orbiting scroll, and a fluid inlet port is formed in said cup-shaped casing, characterised in that said fluid inlet port is located radially outwardly of and at the same axial location as said rotation preventing/thrust bearing device.

[0013] The rotation preventing mechanism may include a fixed ring fastened against the inner surface of said front end plate, an orbiting ring fastened against the end surface of said circular end plate and ball elements each of which is retained a pair of holes formed in both rings. A cut-out portion is suitable formed in the periphery of the fixed ring, at the same angular position as the fluid inlet port. An oil passageway may be formed in the front end plate to an interior portion of the casing with a shaft seal cavity in the front end plate. In this construction, lubri­cation and cooling of bearing portions can be easily done.

[0014] 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 compressor illustrating the prior lubricating mechanism.

Figure 2 is a vertical sectional view of compressor according to one embodiment of this invention.

Figure 3 is an exploded perspective view of driving mechanism in embodiment of Figure 2.

Figure 4 is an exploded perspective view of rotation preventing/thrust bearing device in embodiment of Figure 2.

Figure 5 is an enlarged sectional view of compressor illustrating a lubricating mechanism according to one embodiment of this invention.

Figure 6 is a sectional view taken along a line A-A in Figure 5.

Figure 7 is a sectional view of compressor illustrating lubricating mechanism according to another embodiment of this invention.

[0015] A prior compressor has the lubricating mechanism which is shown in Figure 1. Such that, a fluid inlet port 2 is formed in housing 1 and located at an outer peripheral portion of a spiral element 3a of orbiting scroll 3. A step portion 2a is formed in fluid inlet port 2. Step portion 2a projects radially inwardly from an inner wall of fluid inlet port 2. Housing 1 is formed with a first oil passageway 4 one end of which opens at the inner wall of fluid inlet port 2 and second oil passageway 5 one end of which opens at a shaft seal cavity 6 includes a shaft seal assembly 7. In the operation, refrigerant gas is introduced into the interior of the housing 1 through inlet port 2. The oil mist suction gas is struck against step portion 2a and separates the oil. Following the flow of suction gas separated oil flows into first oil passageway 4, and then flows out to the shaft seal cavity 6 through second oil passageway 5. The oil which flows into the shaft seal cavity lubricates and cools the shaft seal assembly 7 and returns to the interior of housing 1 while lubricating the bearing portions.

[0016] In this mechanism, step portion for separating and accumulating the oil must be formed in the fluid inlet port and oil passageway connected between shaft seal cavity and fluid inlet port must be formed in housing with increase the wall thickness of housing. Therefore, the construction and forming of the housing will be complicated and increase the diameter of housing.

[0017] Referring to Figure 2, a refrigerant compressor unit in accordance with the present invention is shown. The 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] Orbiting scroll 26 is disposed in front chamber 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 inter­fit 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.

[0027] Referring to Figures 2 and 3, 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.

[0028] 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 opposit 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 332, as shown in Figure 3, 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 32 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.

[0029] Referring to Figure 2 and 4, a 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. Both rings 371 and 372 have a plurality of pairs of adjacent circular indentations or holes 374 and 375 and one ball 373 is retained in each of these pairs of holes 374 and 375. As shown in Figures, both ring 371 and 372 are formed by separat 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.

[0030] 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.

[0031] In this embodiment of the invention, as shown in Figure 2, 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.

[0032] Figures 5 and 6 show another embodiment of a compressor according to this invention, in which the lubricating mechanism for the shaft seal assembly is modified. In this embodiment, a lubricating oil passageway 113 is formed in the front end plate 11 for connecting the shaft seal cavity of the front end plate 11 to the suction chamber 31. The outer peripheral portion of fixed ring 371 is provided with a cut-out portion 40 which is located at the same angular position as the fluid inlet port 35. One end of the oil passageway 113 opens at the inner surface of front end plate 11 adjacent to the cut-out portion 40 of fixed ring 371. As shown in Figure 6, a part of the opening of the oil passageway 113 is covered by the fixed ring 371.

[0033] In operation, a part of the suction refrigerant gas which is introduced into the suction chamber 31 through fluid inlet port 35 strikes against a bottom surface 401 of cut-out portion 40. The lubricating oil is separated from the suction refrigerant gas and accumulates on a bottom surface 401 of cut-out portion 40. Following the flow of suction gas, the accumulated oil flows into oil passageway 113, and then flows out to the shaft seal cavity of front end plate 11. The oil which flows into the shaft seal cavity lubricates and cools the shaft seal assembly 20 and returns to suction chamber 31 through bearing 16 while lubricate bearing 16. In the embodiment shown in Figure 6, the cut-out portion 40 is arc-­shaped. Alternatively, the cut-out portion 40 may be U-shaped, as shown in Figure 7.

[0034] Furthermore, the bottom surface 401 of cut-out portion 40 usually makes a right angle with the end surface of fixed ring 371. Alternatively, the bottom surface 401 of cut-out portion 40 may be formed by an inclined surface, as shown in Figure 5.

[0035] The invention has been described in detail in connection with preferred embodiments, but these are examples only and this invention is not restricted thereto. It will be easily understood by those skilled in the art that the other variations and modifi­cations can be easily made within the scope of this invention.

Claims

1. In a scroll type compressor including a housing (1) comprising a front end plate (11) and a cup shaped casing (12), a fixed scroll (8) fixedly disposed within said housing (1) and having a fixed scroll end plate (81) from which a first wrap (8a) extends, an orbiting scroll (3) having an orbiting scroll end plate (31) from which a second wrap (3a) extends, said first and second wraps (8a, 3a) 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 (3) to effect the orbital motion of said orbiting scroll (3) while preventing the rotation of said orbiting scroll (3), and thus changing the volume of said fluid pockets due to the orbital motion of said orbiting scroll (3), characterized by:
a fluid inlet port (2) formed in said cup shaped casing (12), 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 therefrom to said seal cavity through said first and second lubricant passageways (4, 5).

2. The scroll type compressor of claim 1 characterized 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).

3. The scroll compressor according to claim 1 or 2, characterized by lubricant passageway means for conveying lubricant from said shaft seal cavity to an intake chamber of the scroll type compressor.

4. A scroll type compressor including a housing (1) adapted to rotatably support a drive shaft (13), said housing (1) including a front end plate (11) and a cup shaped casing (12), a fixed scroll (8) fixedly disposed within said housing (1) and having an end plate (81) from which a first wrap (8a) extends, an orbiting scroll (3) having an end plate (31) from which a second wrap (3a) extends, said first and second wraps (8a, 3a) 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, said fixed scroll end plate (81) dividing the inner chamber of said cup shaped casing (12) into a discharge chamber (17) and a suction chamber (18), a driving mechanism operatively connected with said orbiting scroll (3) to effect the orbiting motion of said orbiting scroll (3) while preventing the rotation of said orbiting scroll (3), said driving mechanism rotatably supported within said housing (1), and a lubricating system for the scroll type compressor, characterized in that the lubricating system comprises:
an inlet port (2) for introducing an oil misted gas into said suction chamber (18) of the scroll compressor;
means (2a) for separating oil from the oil misted suction gas; and
passageway means (4, 5) for conveying the separated oil to lubricate the rotating elements of the scroll compressor.

5. The scroll type compressor of claim 4, characterized in that said separating means comprises a step portion (2a) projecting radially inwardly from an inner wall of said inlet port (2).

6. The scroll type compressor of claim 5, characterized in that said step portion (2a) has a flange (2b) formed on it generally perpendicular to the radially inner end of said step portion (2a).

7. The scroll type compressor of claim 5 or 6, characterized in that said passageway means (4, 5) comprise a first passageway (4) one end of which opens to the inner wall of said inlet port (2) adjacent to said step portion (2a), and a second passageway (5) formed through said front end plate (11), said second passageway (5) connecting said first passageway (4) with a shaft seal cavity formed in said front end plate (11).

Drawing