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Patent Searching and Data


Title:
COMPRESSOR
Document Type and Number:
WIPO Patent Application WO/2005/040610
Kind Code:
A1
Abstract:
A lower balance weight is formed of a thick disk plate having the same outer diameter as that of a rotor. A semicircular recess is provided in an upper end surface of the lower balance weight such that a surface of the rotor which comes into contact with a lower end surface remains. The lower balance weight is provided at its central portion with a through hole through which a shaft can be inserted. A lower end surface of the lower balance weight is provided with a countersunk hole in which a lower end of a rivet is accommodated. By using this structure, since a lower end surface and a side surface of the lower balance weight do not have asperities which stir the main flow of working fluid, stirring of the working fluid flowing caused by rotation of the rotor in the lower space is suppressed, oil drops mixed in the working fluid are prevented from being finely divided by the stirring of the oil drops, the oil drops fall downward due to gravity in the lower space, and the oil separation from the working fluid is promoted.

Inventors:
OKAICHI ATSUO
HASEGAWA HIROSHI
NISHIWAKI FUMITOSHI
Application Number:
PCT/JP2004/016368
Publication Date:
May 06, 2005
Filing Date:
October 28, 2004
Export Citation:
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Assignee:
MATSUSHITA ELECTRIC IND CO LTD (JP)
OKAICHI ATSUO
HASEGAWA HIROSHI
NISHIWAKI FUMITOSHI
International Classes:
F04B35/04; F04C23/00; F04C29/00; F04C29/02; H02K7/04; H02K7/14; F04C18/356; (IPC1-7): F04B35/04; F04C23/00; H02K7/04
Foreign References:
US5520526A1996-05-28
EP0622885A21994-11-02
US6540489B12003-04-01
US20030190247A12003-10-09
US2089626A1937-08-10
EP1330010A12003-07-23
Attorney, Agent or Firm:
Shimizu, Yoshihiro (Yashiro Building 14-4, Takadanobaba 2-chom, Shinjuku-ku Tokyo, JP)
Download PDF:
Claims:
CLAIMS
1. A compressor comprising: a container; a compressor mechanism configured to compress aworking fluid, said compressor mechanism being disposed in said container; a motor including a stator and a rotor, said motor being disposed in said container; a shaft configured to transmit rotation of said rotor to said compressor mechanism; and an upper balance weight and a lower balance weight configured to eliminate unbalance around a center axis of said shaft, said upper balance weight and said lower balance weight being fixed to upper and lower end surfaces of said rotor, respectively; wherein at least one of an end surface and a side surface of at least one of said rotor, said upper balance weight and said lower balance weight which faces a main flow of the working fluid is formed into a flat and smooth shape.
2. A compressor comprising: a container; a compressor mechanism configured to compress a working fluid, said compressor mechanism being disposed in said container; a motor including a stator and a rotor, said motor being disposed in said container; a shaft configured to transmit rotation of said rotor to said compressor mechanism; and an upper balance weight and a lower balance weight configured to eliminate unbalance around a center axis of said shaft, said upper balance weight and said lower balance weight being fixed to upper and lower end surfaces of said rotor, respectively; wherein at least one of an end surface and a side surface of at least one of said rotor, said upper balance weight and said lower balance weight which faces a main flow of the working fluid is formed into a rotation body shape with respect to the center axis of said shaft.
3. A compressor according to claim 2, wherein the rotation body shape is a substantially columnar shape.
4. A compressor according to claim 2, wherein at least one of said upper balance weight and said lower balance weight is formed into the rotation body shape.
5. A compressor according to claim 2, wherein said upper balance weight covers an upper end surface of said rotor and an upper tip end of said shaft, and said lower balance weight covers a lower end surface of said rotor.
6. A compressor according to claim 2, wherein at least one of said upper balance weight and said lower balance weight comprises a thick disk plate, and wherein a recess which is asymmetric with respect to the center axis of said shaft is provided in an end surface portion of said thick disk plate which comes into contact with said rotor.
7. A compressor according to claim 2, wherein at least one of said upper balance weight and said lower balance weight comprises an inner balance weight which is asymmetric with respect to the center axis of said shaft, and an outer cover configured to envelope said inner balance weight, and wherein at least one of an end surface and a side surface of said outer cover which faces a main flow of the working fluid is formed into the rotation body shape.
8. A compressor according to claim 2, wherein at least one of said upper balance weight and said lower balance weight comprises a thick disk plate in which materials having different densities are disposed to be asymmetric with respect to the center axis of said shaft.
9. A compressor according to claim 1, wherein each of said rotor, said upper balance weight fixed to the upper end surface of said rotor, and said lower balance weight fixed to the lower end surface of said rotor includes a communication hole configured to bring an upper end surface of said upper balance weight and a lower end surface of said lower balance weight into communication with each other, and wherein a rivet is disposed in said communication hole, said rivet having swaged ends and being configured to fix said rotor, said upper balance weight and said lower balance weight to one another; and wherein at least one of the upper end surface of said upper balance weight and the lower end surface of said lower balance weight is provided with a countersunk hole into which the swaged end of said rivet is accommodated.
10. A compressor according to claim 1, wherein adjoining side surfaces of said rotor, said upper balance weight and said lower balance weight are welded and fixed to each other.
11. A compressor according to claim 1, wherein the working fluid is carbon dioxide.
12. A compressor according to claim 2, wherein adjoining side surfaces of said rotor, said upper balance weight and said lower balance weight are welded and fixed to each other.
13. A compressor according to claim 2, wherein the working fluid is carbon dioxide.
14. A compressor comprising: a container; a compressor mechanism configured to compress a working fluid, said compressor mechanism being disposed in said container; a motor including a stator and a rotor, said motor being disposed in said container; a shaft configured to transmit rotation of said rotor to said compressor mechanism; an upper balance weight and a lower balance weight configured to eliminate unbalance around a center axis of said shaft, said upper balance weight and said lower balance weight being fixed to upper and lower end surfaces of said rotor, respectively; and a rivet including swaged ends, said rivet being disposed in a through hole extending through said upper balance weight, said lower balance weight, and said rotor.
15. A compressor according to claim 14, wherein an upper end surface of said upper balance weight and a lower end surface of said lower balance weight are each provided with a countersunk hole into which one of the swaged ends of said rivet is accommodated.
16. A compressor according to claim 14, wherein at least one of said upper balance weight and said lower balance weight is formed into a rotation body shape with respect to the center axis of said shaft.
17. A compressor according to claim 16, wherein the rotation body shape is a substantially columnar shape.
18. A compressor according to claim 14, wherein said upper balance weight covers an upper end surface of said rotor and an upper tip end of said shaft, and said lower balance weight covers a lower end surface of said rotor.
19. A compressor according to claim 14, wherein at least one of said upper balance weight and said lower balance weight comprises a thick disk plate, and wherein a recess which is asymmetric with respect to the center axis of said shaft is provided in an end surface portion of said thick disk plate which comes into contact with said rotor.
20. A compressor according to claim 14, wherein at least one of said upper balance weight and said lower balance weight comprises an inner balance weight which is asymmetric with respect to the center axis of said shaft and an outer cover configured to envelope said inner balance weight, and wherein at least one of an end surface and a side surface of said outer cover which faces a main flow of the working fluid is formed into the rotation body shape.
Description:
COMPRESSOR Technical Field The present invention relates to a compressor used for a refrigerator-freezer, an air conditioner and the like.

Background of the Invetion A compressor such as a rotary compressor is widely used for a refrigerator-freezer, an air conditioner and the like because it is small in size and has a simple structure. A structure of the compressor such as the rotary compressor is described in a non-patent document 1, ["Air-Conditioning and Refrigeration handbook", new edition 5, volume 11, machine", Air-Conditioning and Refrigeration Institute, 1993, paragraphs 30 to 43]. The structure of the conventional compressor will be explained using Fig. 14 based on the rotary compressor. Fig.

14 is a vertical sectional view of the conventional rotary compressor.

The rotary compressor shown in Fig. 14 includes a container 1, a compressor mechanism disposed on a lower portion of the container 1, and a motor disposed on an upper portion of the compressor mechanism. The compressor mechanism includes a shaft 2 having an eccentric portion 2a, a cylinder 3, a roller 4, a vane 5, a spring 6, an upper bearing member 7 having a discharge hole 7a, and a lower bearing member 8. A suction chamber and a compression chamber (not shown) are formed in a space between the cylinder 3 and the roller 4 sandwiched between the upper bearing member 7 and the lower bearing member 8.

The motor has a stator 11 which includes a coil end llc and a coil end lid projecting from a lower end surface lla and an upper end surface llb. The stator 11 is fixed to the inside of the container 1. The motor also includes a rotor 12 fixed to a shaft 2. The stator 11 is provided at its outer periphery with a plurality of notches lle serving as passages for working fluid. A gap 22 is provided between the stator 11 and the rotor 12.

A lower end surface 12a and an upper end surface 12b of the rotor 12 are respectively provided with a lower balance weight 13 and an upper balance weight 14 for eliminating unbalance around the center axis L of the shaft 2. The lower balance weight 13, the rotor 12 and the upper balance weight 14 are provided with through holes 16 which bring the lower balance weight 13 and the rotor 12 into communication with each other and bring the upper balance weight 14 and the rotor 12 into communication with each other. Both ends of each of the through holes 16 are swaged using a rivet 15, and the lower balance weight 13, the rotor 12 and the upper balance weight 14 are fixed to one another.

The container 1 includes an introduction terminal 17 for energizing the stator 11, a suction pipe 18 for introducing the working fluid into the suction chamber, a discharge pipe 19 for discharging the working fluid out from the container 1, and an oil reservoir 20 provided in a lower portion of the container 1 for reserving refrigeration oil.

The operation of the rotary compressor having the above-described structure will be explained.

If the stator 11 is energized through the introduction terminal 17 to rotate the rotor 12, the roller 4 is eccentrically rotated by the eccentric portion 2a, and volumes of the suction chamber and the compression chamber are varied. As a result, the working fluid is sucked into the suction chamber from the suction pipe 18 and is compressed in the compression chamber.

The compressed working fluid is supplied from the oil reservoir 20 and is mixed with a refrigeration oil which lubricates the compressor mechanism and in this state, the working fluid is injected into a lower space 21 of the motor through the discharge hole 7a. Most of the injected working fluid collides against a lower end surface 12a of the rotor 12, the lower balance weight 13 and a lower end 15a of the rivet 15 and then, generates a strong turning flow by the rotation of the rotor 12. A portion of oil drops mixed with the working fluid attaches to an inner wall of the container 1 by the centrifugal force or falls downward due to gravity and is separated from the working oil and returns into the oil reservoir 20 while the working fluid stays in the lower space 21 as the turning flow.

In a state in which the working fluid includes the oil drops which are not separated, the working fluid passes through the notches lle and the gap 22, and is injected into an upper space 23 of the motor. Most of the injected working fluid flows toward the discharge pipe 19. At that time, a portion of the working fluid passes in the vicinity of an upper end surface 12b of the rotor 12, the upper balance weight 14, an upper end 15b of the rivet 15 and a shaft projection 2b projecting from the upper end surface 12b, and generates a turning flow due to the rotation of these elements. A portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 due to the centrifugal force while the working fluid stays in the upper space 23, or falls downward due to gravity and is separated from the working oil and returns into the oil reservoir 20 along the inner wall of the container 1 or a wall surface of the stator 11. The working fluid still including oil drops which are not yet separated from the working oil is discharged from the discharge pipe 19.

In the compressor such as the rotary compressor, the working fluid and refrigeration oil which are compressed when a sliding surface of the compressor mechanism is lubricated are mixed, and a portion of the refrigeration oil reserved in the oil reservoir 20 is discharged out from the container 1 of the compressor during the process of the operation of the compressor. However, in the case of a compressor in which a large amount of refrigeration oil is discharged, since the oil level of the refrigeration oil in the oil reservoir 20 is lowered, the supply oil amount becomes insufficient, and the lubrication of the compression mechanism becomes insufficient, the reliability is deteriorated, the sealing of the compression mechanism becomes insufficient, and the efficiency of the compressor is deteriorated. Further, the refrigeration oil discharged from the compressor attaches to an inner wall of a tube of a heat exchanger to deteriorate the heat transfer coefficient between the working fluid and a wall surface in the heat exchanger tube. Thus, the performance of the refrigeration cycle is deteriorated. Therefore, the oil separating efficiency of the working fluid in the container 1 of the compressor is enhanced, and the discharging amount of the refrigeration oil is reduced.

As a structure for separating the refrigeration oil from the working fluid, there is a method to use an oil separating plate provided on an upper portion of the rotor 12 of the rotary compressor as described in a patent document 1, [Japanese Patent ApplicationLaid-openNo. H8-28476 (paragraph6, Figs. 1 to 3)].

Fig. 15 shows a detailed sectional view of a periphery of the oil separating plate of the conventional compressor. The rotor 12 has an upper end plate 31a and a lower end plate 31b for closing the inserting holes of a permanent magnet 30. A plurality of through holes 12c are formed so as to penetrate the rotor 12 in the vertical direction. An oil separating plate 33 forms an oil separating space 32 in an upper portion of the rotor 12. The oil separating plate 33 is disposed above exits of the through holes 12c. The oil separating plate 33 is fixed by a fixing member 34.

In the compressor having the above-described structure, a portion of the working fluid including oil drops discharged into the lower space 21 of the motor from the compressor mechanism flows into the oil separating space 32 through the through holes 12c formed in the rotor 12. Here, the working fluid is discharged radially from an outer peripheral exit 32a of the oil separating plate 33 by the centrifugal force, and is blown against the coil end lld of the stator 11, and the working fluid and the refrigeration oil included in the working fluid are separated.

Only the working fluid from which the refrigeration oil is separated flows upward, and is discharged out from the discharge pipe 19 provided on the upper portion of the container 1. On the other hand, refrigeration oil attached to the coil end lid of the stator 11 falls downward and returns into the oil reservoir 20 formed in the bottom of the container 1.

As described above, in the conventional compressor as shown in Fig. 14, most of the working fluid injected into the lower space 21 of the motor from the discharge hole 7a of the compression mechanism collides against the lower end surface 12a of the rotor 12, the lower balance weight 13 and the lower end 15a of the rivet 15 and then, produces a strong turning flow by the rotation of the rotor 12. A portion of the working fluid injected into the upper space 23 of the motor passes in the vicinity of the upper end surface 12b of the rotor 12, the upper balance weight 14, the upper end 15b of the rivet 15 and the shaft projection 2b, and produces a strong turning flow by the rotation of these elements. At that time, the oil drops of the refrigeration oil included in the working fluid are stirred by the turning flow and finely divided. Since the turning flows in the lower space 21 and the upper space 23 increase the flow velocity of the working fluid, oil drops are easily transferred by the working fluid. Thus, it is difficult to completely separate the refrigeration oil from the working fluid by solely using the separating method for separating the oil drops using the centrifugal force and gravity.

The lower balance weight 13 and the upper balance weight 14 are fixed to the lower end surface 12a and the upper end surface 12b of the rotor 12 by means of the rivets 15. As a result, a large number of asperities are formed on the lower end surface 12a and the upper end surface 12b, and the asperities enhance the stirring effect of a flowing place by the rotation of the asperities. Therefore, the oil drops of the refrigeration oil included in the working fluid are further finely divided and it becomes difficult to separate the oil drops from the working fluid.

As a method for separating the oil drops which are stirred and finely divided from the working fluid, a structure shown in Fig. 15 is used. In this case, of the working fluid flowing from the lower space 21 to the upper space 23, this method is effective only for working fluid passing through the through holes 12c, and it is impossible to separate the oil drops from working fluid which passes through the notches lle or the gap 22. Further, due to the rotation of the oil separating plate 33 provided on an upper portion of the rotor 12, the concave shape of the outer peripheral exit 32a and the convex shape of a head 34a of a fixing member 34 promote the stirring effect of the working fluid in the upper space 23, and there is a problem that it becomes more difficult to separate the refrigeration oil in the upper space 23.

As another method, the volume of each of the lower space 21 and the upper space 23 is increased, and a time during which the working fluid stays in such spaces is elongated, and separation of the oil drop of the refrigeration oil is promoted due to gravity. However, in this case also, it is difficult to eliminate the influence of the stirring, and there is another problem that the compressor is increased in size.

The above description is based on the vertical type rotary compressor, but the same is applied to the conventional scroll compressor. Irrespective of a difference between the vertical type and the lateral type or irrespective of a difference of the compressing manners, if most working fluid passes in the vicinity of an end surface of the rotor while working fluid discharged from the compression mechanism is discharged from the discharge pipe provided on the container, the same problem is caused.

The above problems are generated irrespective of the particular kind of working fluid used. Nonetheless, the problems are especially experienced when the refrigeration cycle uses a working fluid comprising carbon dioxide as a main ingredient since the pressure of the working fluid discharged from the compression chamber exceeds a critical pressure, the working fluid in the container is brought into a supercriticaL state, an amount of refrigeration oil solved in the working fluid is increased, and a density ratio (refrigeration oil/working fluid) between the working fluid and the refrigeration oil is reduced by about half as compared with conventional flon or the like. Therefore, there is a problem that this makes it especially more difficult to separate the oil in the container. Further, since the density of carbon dioxide in the container becomes about two times that of flon or the like, windage loss caused by rotation of the rotor is increased, and loss generated in the compressor becomes greater as compared with flon or the like.

The present invention has been accomplished to solve the above problems, and it is an object of the invention to provide a compressor capable of easily and inexpensively enhancing the oil separating efficiency without deteriorating the efficiency of the motor, capable of reducing the amount of refrigeration oil to be taken out from the container, and capable of enhancing the reliability of the compressor and obtaining an efficient refrigeration cycle.

Summary of the Invention A first aspect of the present invention provides a compressor comprising a container; a compressor mechanism configured to compresses working fluid, the compressor mechanism being disposed in the container; a motor including a stator and a rotor, the motor being disposed in the container; a shaft configured to transmit rotation of the rotor to the compressor mechanism; and an upper balance weight and a lower balance weight configured to eliminate unbalance around a center axis of the shaft, the upper balance weight and the lower balance weight being fixed to upper and lower end surfaces of the rotor, respectively ; wherein at least one of an end surface and a side surface of at least one of the rotor, the upper balance weight and the lower balance weight which faces a main flow of the working fluid is formed into a flat and smooth shape.

According to this aspect, at least one of the end surface and the side surface of at least one of the rotor, the upper balance weight and the lower balance weight which faces the main flow of the working fluid has no asperities which increase an area that comes into contact with the working fluid.

Therefore, the turning flow is suppressed, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

A second aspect of the invention provides a compressor comprising a container; a compressor mechanism configured to compress a working fluid, the compressor mechanism being disposed in the container; a motor including a stator and a rotor, the motor being disposed in the container; a shaft configured to transmit rotation of the rotor to the compressor mechanism; and an upper balance weight and a lower balance weight configured to eliminate unbalance around a center axis of the shaft, the upper balance weight and the lower balance weight being fixed to upper and lower end surfaces of the rotor, respectively; wherein at least one of an end surface and a side surface of at least one of the rotor, the upper balance weight and the lower balance weight which faces a main flow of the working fluid is formed into a rotation body shape with respect to the center axis of the shaft.

According to this aspect, at least one of the end surface and the side surface of at least one of the rotor, the upper balance weight and the lower balance weight which faces the main flow of the working fluid has no asperities which stir the main flow of the working fluid in the rotational direction.

Therefore, the turning flow is suppressed, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to a third aspect of the invention, in the compressor of the second aspect, the rotation body shape is a substantially columnar shape.

According to this aspect, since the rotation body shape is a substantially columnar shape, its surface is a flat surface having no asperities in the rotational direction. Therefore, the turning flow is suppressed, the area of the end surface or the side surface which comes into contact with the main flow of the working fluid is reduced as compared with a rotation body shape provided at its surface with asperities, and a stirring degree of the main flow of the working fluid can be reduced.

According to a fourth aspect of the invention, in the compressor of the second aspect, at least one of the upper balance weight and the lower balance weight is formed into the rotation body shape.

According to this aspect, the upper end surface and the lower end surface of the rotor which face the lower space and the upper space of the motor and which largely affect the working fluid have no asperities which stir the main flow of the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow.

The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to a fifth aspect of the invention, in the compressor of the second aspect, the upper balance weight covers an upper end surface of the rotor and an upper tip end of the shaft, and the lower balance weight covers a lower end surface of the rotor.

According to this aspect, the upper balance weight and the lower balance weight which face the lower space and the upper space of the motor and which largely affect the working fluid have no asperities which stir the main flow of the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow.

The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to a sixth aspect of the invention, in the compressor of the second aspect, at least one of the upper balance weight and the lower balance weight comprises a thick disk plate, and wherein a recess which is asymmetric with respect to the center axis of the shaft is provided in an end surface portion of the thick disk plate which comes into contact with the rotor.

According to this aspect, the upper balance weight and the lower balance weight which face the lower space and the upper space of the motor and which largely affect the working <BR> <BR> fluid are of substantially columnar shapes having no asperities which stir the main flow of the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided.

Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to a seventh aspect of the invention, in the compressor of the second aspect, at least one of the upper balance weight and the lower balance weight comprises an inner balance weight which is asymmetric with respect to the center axis of the shaft, and an outer cover configured to envelope the inner balance weight, and wherein at least one of an end surface and a side surface which faces a main flow of the working fluid is formed into the rotation body shape.

According to this aspect, the upper balance weight and the lower balance weight which face the lower space and the upper space of the motor and which largely affect the working fluid have no asperities which stir the main flow of the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow.

The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to an eighth aspect of the invention, in the compressor of the second aspect, at least one of the upper balance weight and the lower balance weight comprises a thick disk plate in which materials having different densities are disposed to be asymmetrically with respect to the center axis of the shaft.

According to this aspect, the upper balance weight and the lower balance weight which face the lower space and the upper space of the motor and which largely affect the working fluid have no asperities which stir the main flow of the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow.

The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to a ninth aspect of the invention, in the compressor of the first aspect, each of the rotor, the upper balance weight fixed to the upper end surface of the rotor, and the lower balance weight fixed to the lower end surface of the rotor includes a communication hole configured to bring an upper end surface of the upper balance weight and a lower end surface of the lower balance weight into communication with each other, and wherein a rivet is disposed in the communication hole, the rivet having swaged ends and being configured to fix the rotor, the upper balance weight and the lower balance weight to one another ; and wherein at least one of the upper end surface of the upper balance weight and the lower end surface of the lower balance weight is provided with a countersunk hole into which the swaged end of the rivet is accommodated.

According to this aspect, ends of the rivets which would stir the main flow of the working fluid if projected are provided so as to not project from lower end surfaces of the upper balance weight and the lower balance weight which face the lower space and the upper space of the motor and which largely affect the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating ends of the rivets and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to a tenth aspect of the invention, in the compressor of the first aspect, adjoining side surfaces of the rotor, the upper balance weight and the lower balance weight are welded and fixed to each other.

According to this aspect, fixing hardware such as a rivet and a bolt which would stir the main flow of the working fluid if projected are provided so as to not project from lower end surfaces of the upper balance weight and the lower balance weight which face the lower space and the upper space of the motor and which largely affect the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating fixing hardware and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to an eleventh aspect of the invention, in the compressor of the first aspect, the working fluid is carbon dioxide.

According to this aspect, since the working fluid is <BR> <BR> prevented from being stirred, i. e. , the refrigeration oil is prevented from being finely divided, carbon dioxide can be used as the working fluid.

According to an twelfth aspect of the invention, in the compressor of the second aspect, adjoining side surfaces of the rotor, the upper balance weight and the lower balance weight are welded and fixed to each other.

According to this aspect, fixing hardware such as a rivet and a bolt which would stir the main flow of the working fluid if projected are provided so as to not project from lower end surfaces of the upper balance weight and the lower balance weight which face the lower space and the upper space of the motor and which largely affect the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating fixing hardware and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to a thirteenth aspect of the invention, in the compressor of the second aspect, the working fluid is carbon dioxide According to this aspect, since the working fluid is <BR> <BR> prevented from being stirred, i. e. , the refrigeration oil is prevented from being finely divided, carbon dioxide can be used as the working fluid.

A fourteenth aspect of the invention provides a compressor comprising a container; a compressor mechanism configured to compress a working fluid, the compressor mechanism being disposed in the container ; a motor including a stator and a rotor, the motor being disposed in the container; a shaft configured to transmit rotation of the rotor to the compressor mechanism; an upper balance weight and a lower balance weight configured to eliminate unbalance around a center axis of the shaft, the upper balance weight and the lower balance weight being fixed to upper and lower end surfaces of the rotor, respectively; and a rivet including swaged ends, the rivet being disposed in a through hole extending through the upper balance weight, the lower balance weight, and the rotor.

According to a fifteenth aspect of the invention, in the compressor of the fourteenth aspect, an upper end surface of the upper balance weight and a lower end surface of the lower balance weight are each provided with a countersunk hole into which one of the swaged ends of the rivet is accommodated.

According to this aspect, ends of the rivets which would stir the main flow of the working fluid if projected are provided so as to not project from lower end surfaces of the upper balance weight and the lower balance weight which face the lower space and the upper space of the motor and which largely affect the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating ends of the rivets and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to a sixteenth aspect of the invention, in the compressor of the fourteenth aspect, at least one of the upper balance weight and the lower balance weight is formed into a rotation body shape with respect to the center axis of the shaft.

According to this aspect, the upper end surface and the lower end surface of the rotor which face the lower space and the upper space of the motor and which largely affect the working fluid have no asperities which stir the main flow of the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow.

The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to a seventeenth aspect of the invention, in the compressor of the sixteenth aspect, the rotation body shape is a substantially columnar shape.

According to this aspect, since the rotation body shape is a substantially columnar shape, its surface is a flat surface having no asperities in the rotational direction. Therefore, the turning flow is suppressed, the area of the end surface or the side surface which comes into contact with the main flow of the working fluid is reduced as compared with a rotation body shape provided at its surface with asperities, and a stirring degree of the main flow of the working fluid can be reduced.

According to a eighteenth aspect of the invention, in the compressor of the fourteenth aspect, the upper balance weight covers an upper end surface of the rotor and an upper tip end of the shaft, and the lower balance weight covers a lower end surface of the rotor.

According to this aspect, the upper balance weight and the lower balance weight which face the lower space and the upper space of the motor and which largely affect the working fluid have no asperities which stir the main flow of the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow.

The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to a nineteenth aspect of the invention, in the compressor of the fourteenth aspect, at least one of the upper balance weight and the lower balance weight comprises a thick disk plate, and wherein a recess which is asymmetric with respect to the center axis of the shaft is provided in an end surface portion of the thick disk plate which comes into contact with the rotor.

According to this aspect, the upper balance weight and the lower balance weight which face the lower space and the upper space of the motor and which largely affect the working <BR> <BR> fluid are of substantially columnar shapes having no asperities which stir the main flow of the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided.

Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to a twentieth aspect of the invention, in the compressor of the fourteenth aspect, at least one of the upper balance weight and the lower balance weight comprises an inner balance weight which is asymmetric with respect to the center axis of the shaft and an outer cover configured to envelope the inner balance weight, and wherein at least one of an end surface and a side surface of the outer cover which faces a main flow of the working fluid is formed into the rotation body shape.

According to this aspect, the upper balance weight and the lower balance weight which face the lower space and the upper space of the motor and which largely affect the working fluid have no asperities which stir the main flow of the working fluid. Therefore, the turning flow is suppressed in the lower space and the upper space, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow.

The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

Brief Description of the Drawings Fig. 1 is a vertical sectional view of a rotary compressor according to a first embodiment of the present invention; Fig. 2 is a transverse sectional view of the rotary compressor shown in Fig. 1 taken along the arrows Z-Z; Fig. 3 is a perspective view of an upper balance weight, a rotor and a lower balance weight of the rotary compressor shown in Fig. 1; Fig. 4 is a perspective view of a state in which the upper balance weight, the rotor and the lower balance weight shown in Fig. 3 are fixed to one another by rivets; Fig. 5 is a vertical sectional view of a rotary compressor of a second embodiment of the invention; Fig. 6 is a perspective view of an upper balance weight, a rotor and a lower balance weight of the rotary compressor shown in Fig. 5; Fig. 7 is a perspective view of a state in which the upper balance weight, the rotor and the lower balance weight shown in Fig. 6 are fixed to one another by welding; Fig. 8 is a vertical sectional view of a rotary compressor of a third embodiment of the invention; Fig. 9 is a perspective view of an upper balance weight, a rotor and a lower balance weight of the rotary compressor shown in Fig. 8; Fig. 10 is a perspective view of a state in which the upper balance weight, the rotor and the lower balance weight shown in Fig. 9 are fixed to one another by rivets; Fig. 11 is a vertical sectional view of a rotary compressor of a fourth embodiment of the invention; Fig. 12 is a perspective view of an upper balance weight, a rotor and a lower balance weight of the rotary compressor shown in Fig. 11; Fig. 13 is a perspective view of a state in which the upper balance weight, the rotor and the lower balance weight shown in Fig. 11 are fixed to one another by welding; Fig. 14 is a vertical sectional view of a conventional rotary compressor; and Fig. 15 is a detailed sectional view of a periphery of an oil separating plate of a conventional compressor.

Detailed Description (First Embodiment) A compressor of a first embodiment of the present invention is a rotary compressor, and has a similar structure as that of the conventional rotary compressor explained using Fig. 14, and the same elements are designated with the same symbols.

Fig. lisa vertical sectional view of the rotary compressor according to the first embodiment of the present invention, Fig. 2 is a transverse sectional view of the rotary compressor shown in Fig. 1 taken along the arrows Z-Z, Fig. 3 is a perspective view of an upper balance weight, a rotor and a lower balance weight of the rotary compressor shown in Fig. 1, and Fig. 4 is a perspective view of a state in which the upper balance weight, the rotor and the lower balance weight shown in Fig.

3 are fixed to one another by using rivets.

The rotary compressor shown in Figs. 1 to 4 includes a container 1, a compressor mechanism disposed in a lower portion of the container 1, and a motor disposed in an upper portion of the compressor mechanism.

As shown in Figs. 1 and 2, the compression mechanism includes a shaft 2 which can rotate around a center axis L, a cylinder 3, a roller 4 which is fitted over an eccentric portion 2a of the shaft 2 and which eccentrically rotates inside the cylinder 3 as the shaft 2 rotates, a vane 5 which reciprocates in a vane groove 3a of the cylinder 3 in a state in which a tip end of the vane 5 is in contact with the roller 4, a spring 6 for pushing the vane 5 against the roller 4, an upper bearing member 7 having a discharge hole 7a and supporting the shaft 2 at an upper side of the cylinder 3, and a lower bearing member 8 supporting the shaft 2 at a lower side of the cylinder 3.

A space between the cylinder 3 and the roller 4 sandwiched between the upper bearing member 7 and the lower bearing member 8 is divided by the vane 5 into a suction chamber 9 and a compression chamber 10.

The motor includes a stator 11 fixed to an inner wall of the container 1, and a rotor 12 fixed to the shaft 2. The stator 11 is provided with a coil end llc projecting from a lower end surface lla of the stator 11, and a coil end lld projecting from an upper end surface llb of the stator 11. The stator 11 is formed by laminating steel plates from its lower end surface 11a to its upper end surface lib. As shown in Figs.

1 and 3, the lower end surface 12a and the upper end surface 12b of the rotor 12 are provided with a lower adjusting balance weight 113 and an upper adjusting balance weight 114 for eliminating unbalance between the rotating shaft 2 and rotor 12. A plurality of notches lie serving as passages for working fluid are provided between the outer periphery of the stator 11 and the inner wall of the container 1. A gap 22 is provided between the stator 11 and the rotor 12.

As shown in Figs. 1 and 2, the container 1 is provided with an introduction terminal 17 for energizing the stator 11 from outside of the container 1, and a suction pipe 18 for introducing the working fluid from the refrigeration cycle into the suction chamber 9 of the compressor mechanism. The container 1 is also provided with a discharge pipe 19 for discharging the working fluid from the container 1 into the refrigeration cycle. The discharge pipe 19 is provided on the opposite side from the compressor mechanism with respect to the rotational motor. The refrigeration oil is reserved in an oil reservoir 20 formed in a bottom of the container 1.

As compared with the conventional rotary compressor shown in Fig. 14, the present embodiment is characterized in that the lower balance weight 113, the rotor 12 and the upper balance weight 114 are provided with through holes 116, rivets 115 are inserted through the through holes 116, a lower end 115a and an upper end 115b of the rivet 115 are swaged so as to minimize or eliminate protrusion, and the lower balance weight 113, the <BR> <BR> rotor 12 and the upper balance weight 114 are fixed to one another.

As shown in Figs. 1 and 3, the lower balance weight 113 is formed of a thick disk plate having the same outer diameter as that of the rotor 12. The thick disk plate includes a <BR> <BR> semicircular recess 11 3b which is provided in an upper end surface 113a of the lower balance weight 113 such that a surface of the semicircular recess 113b that is in contact with the lower end surface 12a of the rotor 12 remains, a through hole 113c which is provided in a central portion of the thick disk plate such that the shaft 2 can penetrate the through hole 113c, a countersunk hole 113e which is provided in the lower end surface 113d on the opposite side of the recess 113b such that the lower end 115a of the rivet 115 is accommodated in the countersunk hole 113e, and a through hole 116. The lower balance weight 113 covers the entire lower end surface 12a of the rotor 12.

The semicircular recess 113b is formed asymmetric with respect to the center axis L in the upper end surface 113a that is in contact with the rotor 12 of the thick disk plate so as to adjust the unbalance of the rotor 12.

As further shown in Figs. 1 and 3, the upper balance weight 114 is formed of a thick disk plate having the same outer diameter as that of the rotor 12. The thick disk plate includes a semicircular recess 114b which is provided in a lower end surface 114a of the upper balance weight 114 such that a surface of the semicircular recess 114b that is in contact with the upper end surface 12b of the rotor 12 remains, a countersunk hole 114d which is provided in the upper end surface 114c on the opposite side of the recess 114b such that the upper end 115b of the rivet 115 is accommodated in the countersunk hole 114d, and through holes 116. The upper balance weight 114 covers the upper end surface 12b of the rotor 12 and the tip end 2c of the shaft 2.

The operation of the rotary compressor having the above-described structure will be explained.

If the stator 11 is energized through the introduction terminal 17 to rotate the rotor 12, the roller 4 is eccentrically rotated by the eccentric portion 2a, and volumes of the suction chamber 9 and the compression chamber 10 are varied. As a result, the working fluid is sucked into the suction chamber 9 from the suction pipe 18 and is compressed in the compression chamber 10. The compressed working fluid is supplied from the oil reservoir 20 to lubricate the sliding surface of the compressor mechanism, and the working fluid is mixed with oil drops of the refrigeration oil which seals the gap. In this state, the working fluid is injected into the lower space 21 which is a flowing place of working fluid provided between the compressor mechanism and the motor.

The working fluid injected into the lower space 21 collides against the lower balance weight 113 which rotates at high speed, the component of turning velocity is transmitted from the lower end surface 113d of the lower balance weight 113 by means of viscosity, and the working fluid produces the turning flow and is dispersed. The oil drops of refrigeration oil having large particle diameters included in the working fluid dispersed in the lower space 21 and oil drops of refrigeration oil which attach the inner wall of the container 1 and whose particle diameters are increased are separated due to gravity caused by a density difference between the working fluid and the refrigeration oil, and return to the oil reservoir 20. The working fluid from which oil drops of refrigeration oil having large particle diameters are separated passes through the notches lle of the stator 11 and the gap 22 between the stator 11 and the rotor 12, and moves to the upper space 23.

The component of turning velocity of the working fluid in the upper space 23 is transmitted from the upper end surface 114c of the upper balance weight 114 and the turning flow is generated. The working fluid which has moved from the lower space 21 to the upper space 23 and produced the turning flow collides against the upper coil end lld or the inner wall of the container 1, oil drops of the refrigeration oil whose particle diameters are increased are separated from the working fluid, and a portion of the working fluid passes in the vicinity of the upper balance weight 114, and is discharged into the outside refrigeration cycle from the discharge pipe 19.

With the above structure, the working fluid injected into the lower space 21 collides against the lower balance weight 113, the lower end surface 113d and a side surface 113f of the lower balance weight 113 which are of a substantially columnar shape, and the lower end surface 113d and the side surface 113f do not have asperities which stir the main flow of the working fluid in the rotational direction. Further, since the columnar lower balance weight 113 covers the lower end surface 12a of the rotor 12, the lower surface of the rotor 12 that faces the lower space 21 does not have asperities which come into contact with the main flow of the working fluid.

Therefore, according to the compressor of the embodiment, the turning flow is suppressed by the lower space 21, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided.

Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

After a portion of the refrigeration oil included in the working fluid is separated from the working fluid in the lower space 21, the working fluid passes through the notches lle or the gap 22 and moves into the upper space 23. A portion of the working fluid passes in the vicinity of the upper balance weight 114, the upper end surface 114c and the side surface 114e of the upper balance weight which are 114 provided using the thick disk plate in a substantially columnar shape, and the upper end surface 114c and the side surface 114e do not have asperities which stir the main flow of the working fluid in the rotational direction. Since the columnar upper balance weight 114 covers the upper end surface 12b of the rotor 12 and the tip end 2c of the shaft 2, the upper surface of the rotor 12 that faces the upper space 23 does not have asperities which come into contact with the main flow of the working fluid.

Therefore, according to the compressor of the embodiment, the turning flow is suppressed by the upper space 23, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided.

Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

In this embodiment, the balance weight has a substantially columnar shape which is one kind of a rotation body shape with respect to the center axis L of the rotor 12, but the balance weight may have other rotational body shapes having no asperities which stir the main flow of the working fluid in the rotational direction, and the latter structure can obtain the same effect as that of the embodiment. However, the balance weight is formed into a substantially columnar shape obtained by rotating a rectangular shape comprising straight sides. As compared with a rotation body shape obtained by rotating a surface comprising corrugated sides, the balance weight is flat and smooth in shape and has a smaller area that comes into contact with the main flow of the working fluid. Therefore, since the columnar balance weight has a lower degree for stirring the main flow of the working fluid, such a balance weight is preferable.

The lower end surface 113d of the lower balance weight 113 and the upper end surface 114c of the upper balance weight 114 are respectively provided with the countersunk hole 113e and the countersunk hole 114d which accommodate the lower end 115a and the upper end 115b of the rivet 115 in a state in which the lower end surface 113d and the upper end surface 114c have no asperities. By using this structure, the lower end 115a and the upper end 115b of the rivet 115 do not project from the lower end surface 113d of the lower balance weight 113 and the upper end surface 114c of the upper balance weight 114.

Thus, the turning flow is suppressed by the lower space 21 and the upper space 23, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

The vertical rotary compressor is explained in this embodiment, but irrespective of the difference between the vertical type and the lateral type, or irrespective of the <BR> <BR> differenceofcompressingmanners, ifthemainflowoftheworking fluid discharged from the compressor mechanism passes in the vicinity of the rotor 12 before the working fluid is discharged from the discharge pipe 19, the same effect can be obtained.

Concerning the compressor having such a structure that the working fluid injected from the discharge hole 7a directly collides against the lower balance weight 13 provided on the lower end surface 12a of the rotor 12 like the conventional rotary compressor shown in Fig. 14, if a surface of the balance weight that comes into contact with the main flow of the working fluid is formed into a substantially columnar shape having no asperities like the lower balance weight 113 of this embodiment, the oil separating performance is further enhanced.

(Second Embodiment) A compressor of a second embodiment of the present invention is similar to the rotary compressor of the first embodiment explained with reference to Figs. 1 to 4 and the conventional rotary compressor explained using Fig. 14, and the same elements are designated with the same symbols.

Explanation of the same structure and its operation will be omitted.

Fig. 5 is a vertical sectional view of the rotary compressor of the second embodiment of the invention, Fig. 6 is a perspective view of an upper balance weight, a rotor and a lower balance weight of the rotary compressor shown in Fig. 5, and Fig. 7 is a perspective view of a state in which the upper balance weight, the rotor and the lower balance weight shown in Fig.

6 are fixed to one another by means of welding.

The rotary compressor of the second embodiment is different from the conventional rotary compressor shown in Fig.

14 in that a lower balance weight 213, a rotor 12 and an upper balance weight 214 are welded and fixed to one another. For example, side surfaces of the rotor, the upper balance weight and the lower balance weight are welded and fixed to one another using nuggets 40 having no protrusion as shown in Fig. 7. The side surface may be adhered using an adhesive.

As shown in Figs. 1-3, the lower balance weight 213 is formed of a thick disk plate having the same outer diameter as that of an outer diameter of the rotor 12. The thick disk plate includes a semicircular recess 213b provided in an upper end surface 213a of the lower balance weight 213 such that a surface of the semicircular recess 213b that comes into contact with the lower end surface 12a of the rotor 12 remains, and a through hole 213c formed in a central portion of the thick disk plate such that the shaft 2 can pass through the through hole 213c. The upper balance weight 214 is formed of a thick disk plate having the same outer diameter as that of the rotor 12, and includes a semicircular recess 214b provided in a lower end surface 214a of the upper balance weight 214 such that a surface of the semicircular recess 214b that comes into contact with the upper end surface 12b of the rotor 12 remains.

The operation of the rotary compressor having such a structure will be explained.

The working fluid injected into the lower space 21 collides against the lower balance weight 213 which rotates at high speed, the component of turning velocity is transmitted from the lower end surface 213d of the lower balance weight 213 by means of viscosity, and the working fluid produces the turning flow and is dispersed. The oil drops of refrigeration oil having large particle diameters included in the working fluid dispersed in the lower space 21 and oil drops of refrigeration oil which attach to the lower coil end or the inner wall of the container 1 and whose particle diameters are increased are separated due to gravity caused by a density difference between the working fluid and the refrigeration oil, and return to the oil reservoir 20. The working fluid from which oil drops of refrigeration oil having large particle diameters are separated passes through the notches lle of the stator 11 and the gap 22 between the stator 11 and the rotor 12, and moves to the upper space 23.

The component of turning velocity of the working fluid in the upper space 23 is transmitted from the upper end surface 214c of the upper balance weight 214 and the turning flow is generated. The working fluid which has moved from the lower space 21 to the upper space 23 and produced the turning flow collides against the upper coil end lid or the inner wall of the container 1, oil drops of the refrigeration oil whose particle diameters are increased are separated from the working fluid, and a portion of the working fluid passes in the vicinity of the upper balance weight 214, and is discharged into the outside refrigeration cycle from the discharge pipe 19.

With the above structure, the working fluid injected into the lower space 21 collides against the lower balance weight 213, the lower end surface 213d and a side surface 213e of the lower balance weight 213 are of a substantially columnar shape, and the lower end surface 213d and the side surface 213e do not have asperities which stir the main flow of the working fluid in the rotational direction. As compared with a rotation body shape obtained by rotating a surface comprising corrugated sides, the balance weight is flat and smooth in shape and has a smaller area that comes into contact with the main flow of the working fluid. Further, since the columnar lower balance weight 213 covers the lower end surface 12a of the rotor 12, the lower surface of the rotor 12 that faces the lower space 21 does not have asperities which come into contact with the main flow of the working fluid.

Therefore, according to the compressor of the embodiment, the turning flow is suppressed by the lower space 21, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided.

Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

After a portion of the refrigeration oil included in the working fluid is separated from the working fluid in the lower space 21, the working fluid passes through the notches lle or the gap 22 and moves into the upper space 23. A portion of the working fluid passes in the vicinity of the upper balance weight 214, the upper end surface 214c and the side surface 214d of the upper balance weight 214 provided using the thick disk plate are of a substantially columnar shape, and the upper end surface 214c and the side surface 214d do not have asperities which stir the main flow of the working fluid in the rotational direction. As compared with a rotation body shape obtained by rotating a surface comprising corrugated sides, the balance weight has a smaller area that comes into contact with the main flow of the working fluid. Since the columnar upper balance weight 214 covers the upper end surface 12b of the rotor 12 and the tip end 2c of the shaft 2, the upper surface of the rotor 12 that faces the upper space 23 does not have asperities which come into contact with the main flow of the working fluid.

Therefore, according to the compressor of the embodiment, the turning flow is suppressed by the upper space 23, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided.

Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

Further, since the side surfaces of the rotor 12, the lower balance weight 213 and the upper balance weight 214 are welded and fixed to one another, ends of fixing hardware such as a rivet, a bolt and the like do not project from the lower end surface 213d of the lower balance weight 213 and the upper end surface 214c of the upper balance weight 214. Therefore, the turning flow is suppressed by the lower space 21 and the upper space 23, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring effect of the turning flow. The oil drops of the refrigeration oil are prevented from colliding against the ends of the fixing hardware such as the rivet and the bolt and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

(Third Embodiment) A compressor of a third embodiment of the present invention is similar to the rotary compressors of the first and second embodiments and the conventional rotary compressor, and the same elements are designated with the same symbols. Explanation of the same structure and its operation will be omitted.

Fig. 8 is averticalsectionalviewof the rotary compressor of the third embodiment of the invention, Fig. 9 is a perspective view of an upper balance weight, a rotor and a lower balance weight of the rotary compressor shown in Fig. 8, and Fig. 10 is a perspective view of a state in which the upper balance weight, the rotor and the lower balance weight shown in Fig.

9 are fixed to one another by rivets.

As shown in Figs. 8 and 9, the rotary compressor of the third embodiment is different from the conventional rotary compressor shown in Fig. 14 in that a lower balance weight 313, a rotor 12 and an upper balance weight 314 are provided with communication holes 316, rivets 315 are inserted into the communication holes 316, a lower end 315a and an upper end 315b of each rivet 315 are swaged so as to prevent or minimize protrusion, the lower balance weight 313, the rotor 12 and the upper balance weight 314 are fixed to one another.

The lower balance weight 313 comprises a semicircular lower inner balance weight 313a which is asymmetric with respect to the center axis L, and a lower outer cover 313b formed of a thick disk plate having the same diameter as that of the rotor 12 and enveloping the lower inner balance weight 313a.

The lower inner balance weight 313a includes a through hole 313c through which the shaft 2 can pass, and a communication <BR> <BR> hole 316 can pass. The lower outer cover 313b includes a circular recess 313bb which has a radius slightly larger than that of the lower inner balance weight 313a and which is provided in a central portion of an upper end surface 313ba of the lower outer cover 313b such that the lower inner balance weight 313a is accommodated in the recess 313bb, a countersunk hole 313bd which is provided in a lower end surface 313bc of the lower outer cover 313b such that the lower end 315a of the rivet 315 is accommodated in the countersunk hole 313bd, a through hole 113c which is provided in a central portion of the lower outer cover 313b such that the shaft 2 can pass through the through hole 113c, and a communication hole 316.

The upper balance weight 314 comprises a semicircular upper inner balance weight 314a, and an upper outer cover 314b formed of a thick disk plate having the same diameter as that of the rotor 12. The upper inner balance weight 314a includes a communication hole 316. The upper outer cover 314b includes a circular recess 314bb which has a radius slightly larger than that of the upper inner balance weight 314a and which is provided in a central portion of a lower end surface 314ba of the upper outer cover 314b such that the upper inner balance weight 314a is accommodated in the recess 314bb, a countersunk hole 314bd which is provided in an upper end surface 314bc of the upper outer cover 314b such that the upper end 315a of the rivet 315 is accommodated in the countersunk hole 314bd, and a communication hole 316.

The operation of the rotary compressor having the above-described structure will be explained.

The working fluid injected into the lower space 21 collides against the lower outer cover 313b which rotates at high speed, the component of turning velocity is transmitted from the lower end surface 313bc of the lower outer cover 313b by means of viscosity, and the working fluid produces the turning flow and is dispersed. The oil drops of refrigeration oil having large particle diameters included in the working fluid dispersed in the lower space 21 and oil drops of refrigeration oil which attach to the lower coil end or the inner wall of the container 1 and whose particle diameters are increased are separated due to gravity caused by a density difference between the working fluid and the refrigeration oil, and return to the oil reservoir 20. The working fluid from which oil drops of refrigeration oil having large particle diameters are separated passes through the notches lle or the gap 22, and moves to the upper space 23.

The component of turning velocity of the working fluid in the upper space 23 is transmitted from the upper end surface 314bc of the upper outer cover 314b and the turning flow is generated. The working fluid which has moved from the lower space 21 to the upper space 23 and produced the turning flow collides against the upper coil end lld or the inner wall of the container 1, oil drops of the refrigeration oil whose particle diameters are increased are separated from the working fluid, and a portion of the working fluid passes in the vicinity of the upper balance weight 314, and is discharged into the outside refrigeration cycle from the discharge pipe 19.

With the above structure, the working fluid injected into the lower space 21 collides against the lower balance weight 313, the lower end surface 313bc and a side surface 313be of the lower outer cover 313b are of a substantially columnar shape, and the lower end surface 313d and the side surface 313f do not have asperities which stir the main flow of the working fluid in the rotational direction. As compared with a rotation body shape obtained by rotating a surface comprising corrugated sides, and the former shape the balance weight is flat and smooth in shape and has a smaller area that comes into contact with the main flow of the working fluid. Further, since the columnar lower outer cover 313b covers the lower end surface 12a of the rotor 12, the lower surface of the rotor 12 does not have asperities which come into contact with the main flow of the working fluid.

Therefore, according to the compressor of the embodiment, the turning flow is suppressed by the lower space 21, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided.

Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

After a portion of the refrigeration oil included in the working fluid is separated from the working fluid in the lower space 21, the working fluid passes through the notches lle or the gap 22 and moves into the upper space 23. A portion of the working fluid passes in the vicinity of the upper balance weight 314, the upper end surface 314bc and the side surface 314be of the upper outer cover 314b provided the thick disk plate is of a substantially columnar shape, and the upper end surface 314bc and the side surface 314be do not have asperities which stir the main flow of the working fluid. As compared with a rotation body shape obtained by rotating a surface comprising corrugated sides, the balance weight is flat and smooth in shape and has a smaller area that comes into contact with the main flow of the working fluid. Since the columnar upper outer cover 314b covers the upper end surface 12b of the rotor 12 and the tip end 2c of the shaft 2, the upper surface of the rotor 12 does not have asperities which come into contact with the main flow of the working fluid.

Therefore, according to the compressor of the embodiment, the turning flow is suppressed by the upper space 23, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided.

Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

The lower end surface 313bc of the lower outer cover 313b and the upper end surface 314bc of the upper outer cover 314b are respectively provided with the countersunk hole 313bd and <BR> <BR> the countersunk hole 314bd for accommodating the lower end 315a<BR> and the upper end 315b of the rivet 315. By using this structure, the lower end 315a and the upper end 315b of the rivet 315 do not project from the lower end surface 313bc of the lower outer cover 313b and the upper end surface 314bc of the upper outer cover 314b. Therefore, the turning flow is suppressed by the lower space 21 and the upper space 23, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating lower end 315a and upper end 315b of the rivet 315 and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

(Fourth Embodiment) A compressor of a fourth embodiment of the present invention is similar to the rotary compressors of the first to third embodiments and the conventional rotary compressor, and the same elements are designated with the same symbols.

Explanation of the same structure and its operation will be omitted.

Fig. 11 is a vertical sectional view of the rotary compressor of the fourth embodiment of the invention, Fig. 12 is a perspective view of an upper balance weight, a rotor and a lower balance weight of the rotary compressor shown in Fig.

11, and Fig. 13 is a perspective view of a state in which the upper balance weight, the rotor and the lower balance weight shown in Fig. 11 are fixed to one another by welding.

The rotary compressor of the fourth embodiment is different from the conventional rotary compressor shown in Fig.

14 in that side surfaces of a lower balance weight 413, a rotor 12 and an upper balance weight 414 are welded and fixed to one another like the second embodiment.

The lower balance weight 413 is formed of a thick disk plate having the same diameter as that of the rotor 12. The thick disk plate is integrally provided with a semicircular plate 413a having a greater density and a semicircular plate 413b having a smaller density which are welded to each other.

That is, the lower balance weight 413 is formed of the thick disk plate in which materials having a different density are disposed asymmetrically. The lower balance weight 413 is provided at its central portion with a through hole 413d through which the shaft 2 can be inserted. The upper balance weight 414 is formed of a thick disk plate having the same diameter as that of the rotor 12. The thick disk plate is integrally provided with a semicircular plate 414a having a greater density and a semicircular plate 414b having a smaller density which are welded to each other.

The operation of the rotary compressor having the above-described structure will be explained.

The working fluid injected into the lower space 21 collides against the lower balance weight 413 which rotates at high speed, the component of turning velocity is transmitted from the lower end surface 413d of the lower balance weight 413 by means of viscosity, and the working fluid produces the turning flow and is dispersed. The oil drops of refrigeration oil having large particle diameters included in the working fluid dispersed in the lower space 21 and oil drops of refrigeration oil which attach to the lower coil end or the inner wall of the container 1 and whose particle diameters are increased are separated due to gravity caused by a density difference between the working fluid and the refrigeration oil, and return to the oil reservoir 20. The working fluid from which oil drops of refrigeration oil having large particle diameters are separated passes through the notches lle or the gap 22, and moves to the upper space 23.

The component of turning velocity of the working fluid in the upper space 23 is transmitted from the upper end surface 414c of the upper balance weight 414 and the turning flow is generated. The working fluid which has moved from the lower space 21 to the upper space 23 and produced the turning flow collides against the upper coil end lld or the inner wall of the container 1, oil drops of the refrigeration oilwhose particle diameters are increased are separated from the working fluid, and a portion of the working fluid passes in the vicinity of the upper balance weight 414, and is discharged into the outside refrigeration cycle from the discharge pipe 19.

With the above structure, the working fluid injected into the lower space 21 collides against the lower balance weight 413, the lower end surface 413c and a side surface 413e of the lower balance weight 413 are of a substantially columnar shape, and the lower end surface 413d and the side surface 413e do not have asperities which stir the main flow of the working fluid in the rotational direction. As compared with a rotation body shape obtained by rotating a surface comprising corrugated sides, the balance weight is flat and smooth in shape and has a smaller area that comes into contact with the main flow of the working fluid. Further, since the columnar lower balance weight 413 covers the lower end surface 12a of the rotor 12, the lower surface of the rotor 12 does not have asperities which come into contact with the main flow of the working fluid.

Therefore, according to the compressor of the embodiment, the turning flow is suppressed by the lower space 21, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided.

Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

After a portion of the refrigeration oil included in the working fluid is separated from the working fluid in the lower space 21, the working fluid passes through the notches lle or the gap 22 and moves into the upper space 23. A portion of the working fluid passes in the vicinity of the upper balance weight 414, the upper end surface 414c and the side surface 414e of the upper balance weight 414 provided by using the thick disk plate are of a substantially columnar shape, and the upper end surface 414c and the side surface 414e do not have asperities which stir the main flow of the working fluid. As compared with a rotation body shape obtained by rotating a surface comprising corrugated sides, the balance weight is flat and smooth in shape and has a smaller area that comes into contact with the main flow of the working fluid. Since the columnar upper balance weight 414 covers the upper end surface 12b of the rotor 12 and the tip end 2c of the shaft 2, the upper surface of the rotor 12 does not have asperities which come into contact with the main flow of the working fluid.

Therefore, according to the compressor of the embodiment, the turning flow is suppressed by the upper space 23, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided.

Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

Further, the side surfaces of the rotor 12, the lower balance weight 413 and the upper balance weight 414 are welded and fixed. By using this structure, ends of the fixing hardware such as the rivet and the bolt do not project from the lower end surface 413d of the lower balance weight 413 and the upper end surface 414c of the upper balance weight 414. Therefore, the turning flow is suppressed by the lower space 21 and the upper space 23, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating ends of fixing hardware such as the rivet and the bolt and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

The effects of the embodiments can be obtained irrespective of the particular kind of working fluid used, but the effect is exhibited more remarkably when carbon dioxide is used as the working fluid. That is, when the refrigeration cycle uses a working fluid mainly comprising carbon dioxide as a main ingredient, since the pressure of the working fluid discharged from the compression chamber exceeds a critical pressure, the working fluid in the container is brought into a supercritical state, an amount of refrigeration oil solved in the working fluid is increased, and a density ratio (refrigeration oil/working fluid) between the working fluid and the refrigeration oil is reduced by about half as compared with conventional flon or the like. Therefore, the density difference between the working fluid and the refrigeration oil is small, and it becomes particularly difficult to separate the oil in the container as compared with flon when the oil drops are finely divided by stirring or collision. Further, since the density of carbon dioxide in the container becomes about two times that of flon or the like, windage loss caused by rotation of the rotor is increased, and loss generated in the compressor becomes greater as compared with flon or the like.

If such carbon dioxide and the compressor of any of the first to fourth embodiments of the invention are used in combination, since the stirring of the working fluid can be prevented, it is possible to enhance the oil separating efficiency of the refrigeration oil, and the windage loss caused by the rotation of the rotor can be reduced. As a result, there is a merit that it is possible to enhance the reliability and performance of the compressor, the efficiency of the refrigeration cycle using this compressor can be enhanced, and carbon dioxide, which is an environmentally friendly refrigerant, can be used.

In the above embodiments, the lower balance weight and the upper balance weight completely cover the lower end surface 12a and the upper end surface 12b of the rotor 12, but when the lower balance weight and the upper balance weight incompletely cover the lower end surface 12a and the upper end surface 12b of the rotor 12, if at least one of the lower end surface 12a and the upper end surface 12b of the rotor 12 is formed into a rotation body shape with respect to the center axis L, the refrigeration oil can be separated from the working fluid more effectively.

That is, the lower end surface 12a and the upper end surface 12b of the rotor 12 face the lower space 21 and the upper space 23 of the motor and affect the main flow of the working fluid.

Therefore, if at least one of the lower end surface 12a and the upper end surface 12b of the rotor 12 is formed into a rotation body shape with respect to the center axis L, the asperities which stir the main flow of the working fluid can be eliminated from at least one of the lower end surface 12a and the upper end surface 12b of the rotor 12 which face the lower space 21 and the upper space 23 of the motor and largely affect the main flow of the working fluid. By using this structure, the turning flow is suppressed in at least one of the lower space 21 and the upper space 23, and the oil drops of the refrigeration oil mixed in the working fluid are restrained from being finely divided by the stirring operation caused by the turning flow.

The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided. Therefore, the falling of the oil drops of the refrigeration oil from the working fluid due to gravity is promoted, and the oil separating performance can be enhanced.

According to the present invention, if the end surface or the side surface of the rotor, the upper balance weight, or the lower balance weight which faces the main flow of the working fluid is formed into a flat and smooth shape, the area which comes into contact with the working fluid is reduced.

Further, if the end surface or the side surface of the rotor, the upper balance weight or the lower balance weight which faces the main flow of the working fluid is formed into a rotation body shape with respect to the center axis of the shaft, the end surface or the side surface of the rotor, the upper balance weight or the lower balance weight which faces the main flow of the working fluid does not have asperities which stir the main flow of the working fluid. Therefore, the turning flow of the working fluid is suppressed, and the oil drops of the refrigeration oil mixed in the working fluid are prevented from being finely divided by the stirring of the turning flow. The oil drops of the refrigeration oil are also prevented from colliding against the rotating asperities and from being finely divided.

By using this structure, the falling of the oil drops of the refrigeration oil due to gravity is promoted, and the oil separating performance can be enhanced. It is possible to enhance the reliability and efficiency of the compressor and the refrigeration cycle using the compressor.

Industrial Applicability As described above, the present invention is suitably applied to a compressor having lubricant oil, and is suitable as a compressor used for a refrigeration cycle such as a refrigerator-freezer, an air conditioner, a boiler and the like.