WO2005028869A1

WO2005028869A1 - Rotational motor and electric compressor

Info

Publication number: WO2005028869A1
Application number: PCT/JP2004/014420
Authority: WO
Inventors: Hiroshi Hasegawa; Atsuo Okaichi; Fumitoshi Nishiwaki
Original assignee: Matsushita Electric Industrial Co. Ltd.
Priority date: 2003-09-24
Filing date: 2004-09-24
Publication date: 2005-03-31
Also published as: JP2006336463A

Abstract

A shielding plate is provided in the vicinity of a lower end surface of a rotor of a rotational motor. A main flowing place of working fluid in a container from the instant when the working fluid is discharged from a discharge hole of an upper bearing member of the compression mechanism to the instant when the working fluid reaches a discharge pipe is isolated from a lower end surface of the rotor. With this, a stirring caused by rotation of the rotor is suppressed, and oil drops of refrigeration oil mixed in the working fluid are prevented from being finely divided by stirring, and the oil drops are allowed to fall in the lower space due to gravity to promote the separation of refrigeration oil from the working fluid.

Description

ROTATIONAL MOTOR AND ELECTRIC COMPRESSOR

Technical Field The present invention relates to a compressor having a container provided therein with a compression mechanism and a rotational motor.

Background of the Invention A hermetical type rotary compressor is widely used for a refrigerator-freezer, air conditioners, and the like because it is small in size and its structure is simple. A structure of the hermetical type rotary compressor such as a rotary compressor and a scroll 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 hermetical type rotary compressor will be explained with reference to Figs. 8 to 10 based on a rotary compressor and a scroll compressor. Fig. 8 is a vertical sectional view of a conventional rotary compressor. The rotary compressor shown in the drawings comprises a container 1, 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, a lower bearing member 8, a stator 11 having coil ends lie and lid projecting from upper and lower end surfaces 11a and lib, respectively, and a rotor 12 fitted over the shaft 2. In the above structure, a portion comprising the stator 11 and the rotor 12 is called a rotational motor, and a portion which forms a suction chamber and a compression chamber (not shown) in the cylinder 3 and which compresses a working fluid as the rotor 12 rotates is called a compression mechanism. An outer periphery of the stator 11 is provided with a plurality of notches lie which function as passages of the working fluid. A gap 18 is provided between the stator 11 and the rotor 12. The container 1 is provided at its upper portion with an introduction terminal 13 for energizing the rotational motor from outside of the container 1, and a discharge pipe 15 for discharging the working fluid from the container 1 into a refrigeration cycle. The container 1 is provided at its side surface with an introducing pipe 14 for introducing the working fluid from the refrigeration cycle into the compression mechanism. The container 1 is provided at its bottom with an oil reservoir 16 where refrigeration oil is reserved. The operation of the rotary compressor having the above-described structure will be explained. If the stator 11 is energized through the introduction terminal 13 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. With this, the working fluid is sucked into the suction chamber from the introducing pipe 14 and is compressed in the compression chamber. The compressed working fluid supplied from the oil reservoir 16 is mixed with a refrigeration oil which lubricated the compression chamber and, in this state, the working fluid is injected into a lower space 17 of the rotational motor through the discharge hole 7a. The injected working fluid collides against a lower end surface 12a of the rotor 12 and then produces a strong turning flow by the rotation of the rotor 12. While the working fluid remains in the lower space 17 as a turning flow, a portion of the oil drops included in the working fluid attaches to an inner wall of the container 1 by a centrifugal force or drops downward due to gravity and returns into the oil reservoir 16. In a state in which the working fluid includes the oil drops which are not separated, the working fluid passes through the notches lie and the gap 18 from the lower space 17, and is injected toward an upper space 19 of the rotational motor. The injected working fluid flows toward the discharge pipe 15 but at that time, a portion of the working fluid passes in the vicinity of an upper end surface 12b of the rotor 12 , and produces the turning flow due to the rotation of the rotor 12. While the working fluid stays in the upper space 19, a portion of the oil drop included in the working fluid attaches to the inner wall of the container 1 by the centrifugal force or drops downward due to the gravity and is separated, and returns into the oil reservoir 16 along the inner wall of the container 1 or a wall surface of the stator 11. The working fluid including the oil drops which are not yet separated is discharged from the discharge pipe 15. Fig. 9 is a vertical sectional view of a conventional scroll compressor. The scroll compressor shown in Fig. 9 comprises a container 31, a shaft 32 having an eccentric portion 32a, a stationary scroll 33 having a spiral lap 33a and a discharge hole 33b, a moving scroll 34 having a spiral lap 34a and turning as the eccentric portion 32a eccentrically rotates, an upper bearing member 36 having the discharge hole 36c and supporting one end of the shaft 32, a stator 39 which has coil ends 39c and 39d projecting at right and left end surfaces 39a and 39b, respectively, and which is shrinkage fitted into the container 31, a rotor 40 shrinkage fitted over the shaft 32, and an auxiliary bearing member 41 supporting the other end of the shaft 32. The lap 33a and the lap 34a are meshed with each other, and a plurality of suction chambers 37 and compression chambers

38 are formed in the stationary scroll 33 and the moving scroll 34. In the above structure, a structure comprising the stator

39 and the rotor 40 is called a rotational motor, and a structure which forms the suction chambers 37 and the compression chambers 38 and which compresses a working fluid as the rotational motor rotates is called a compression mechanism. An outer periphery of the stator 39 is provided with a plurality of notches 39e which function as passages of the working fluid. A gap 48 is formed between the stator 39 and the rotor 40. The container 31 is provided with an introduction terminal 42 for energizing the rotational motor from outside of the container 31. The container 31 is also provided with an introducing pipe 43 for introducing the working fluid into the suction chambers 37 from the refrigeration cycle, and a discharge pipe 44 for discharging the working fluid into the refrigeration cycle from the container 31. Refrigeration oil is reserved in an oil reservoir 45 formed in a lower portion of the container 31, and the refrigeration oil is drawn up by an oil supply pump 46 from the oil reservoir 45, and is supplied to the compression mechanism. The operation of the scroll compressor having the above-described structure will be explained. If the stator 39 is energized through the introduction terminal 42 to rotate the rotor 40, the moving scroll 34 turns, and volumes of the suction chambers 37 and the compression chambers 38 are varied. With this, the working fluid is sucked from the introducing pipe 43 into the suction chambers 37, and is compressed in the compression chambers 38. The compressed working fluid is supplied from the oil reservoir 45, and is mixed with oil drops of the refrigeration oil which lubricated a sliding surface of the compression mechanism and, in this state, the working fluid is injected into a right space 47 of the rotational motor through the discharge holes 33b and 36c. The injected working fluid produces a turning flow by rotation of a right end surface 40a of the rotor 39. While the working fluid stays in the right space 47 as the turning flow, a portion of the oil drops included in the working fluid attach to the inner wall of the container 1 by the centrifugal force or drop due to the gravity, and is separated from the working fluid and returns into the oil reservoir 45. In a state in which the working fluid includes oil drops which are not yet separated, the working fluid passes through the notches 39e or the gap 48 from the right space 47, and is injected into a left space 49 of the rotational motor. The injected working fluid flows toward the discharge pipe 44 but at that time, a portion of the working fluid passes in the vicinity of a left end surface 40b of the rotor 40, and produces a turning flow due to rotation of the rotor 40. While the working fluid remains in the left space 49, a portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 by the centrifugal force or drops downward due to gravity and is separated and returns into the oil reservoir 45. The working fluid including the oil drops which are not yet separated is discharged from the discharge pipe 44. In the hermetical type compressor such as the rotary compressor and the scroll compressor, in order to lubricate the sliding surface of the compression mechanism and to seal the gap, a portion of the refrigeration oil reserved in the oil reservoir is discharged out from the container 1, 31 of the compressor in the course of operation of the compressor, but in the case of a compressor having a high amount of discharged refrigeration oil, since the oil level of the refrigeration oil in the oil reservoir 16, 45 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 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 sur ace 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 , 31 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 shown in a patent document 1, [Japanese Patent Application Laid-open No.H8-28476 (paragraph 6, Figs.1 to3)]. Fig. 10 shows a detailed sectional view of a periphery of the oil separating plate. The rotor 12 has an upper end plate 21a and a lower end plate 21b for closing inserting holes of a permanent magnet 20. A plurality of through holes 12c formed in the rotor 12 are provided to penetrate the rotor 12 in the vertical direction, and an oil separating plate 23 which is disposed above exits of the through holes 12c and which forms an oil separating space 22 between itself and an upper end surface of the rotor 12 are fixed to the rotor 12 by a fixing member 24. According to the compressor having such a structure, a portion of the working fluid including oil drops discharged into the lower space 17 of the rotational motor from the compression mechanism flows into the oil separating space 22 through the through holes 12c formed in the rotor 12. The working fluid is radially discharged from the outer peripheral exit of the oil separating plate 23, and blows against the coil end lid of the stator 11, and separates the refrigeration oil included in the working fluid. Only the working fluid from which the refrigeration oil is separated flows upward, and is discharged out from the discharge pipe 15 provided on the upper portion in the container 1. On the other hand, refrigeration oil attached to the coil end lid of the stator 11 drops downward and returns into the oil reservoir 16 formed in the bottom of the container 1. As described above, in the conventional rotary compressor, the working fluid injected into the lower space 17 of the rotational motor from the discharge hole 7a of the compression mechanism produces the strong turning flow by rotation of the rotor 12. The working fluid injected into the upper space 19 also produces the turning flow due to the rotation of the rotor 12. Similarly, the working fluid injected into the right space 47 and the left space 49 of the scroll compressor produces the turning flow due to the rotation of the rotor 40. At that time, the oil drops of the refrigeration oil included in the working fluid are stirred by the turning flow and are finely divided. Therefore, it is difficult to completely separate the refrigeration oil from the working fluid by the separating method using the turning flow in the lower space 17 and the upper space 19 as well as the right space 47 and the left space 49 by the centrifugal force and gravity. Each of the lower end surf ce 12a and the upper end surface 12b of the rotor 12 is provided with a balancer 12d for overcoming the unbalance state of the roller 4 and the eccentric portion 2a of the shaft 2. Similarly, each of the right end surface 40a and the left end surface 40b of the rotor 40 is provided with a balancer 40c. In the case of a brushless DC motor, a bolt or a rivet (not shown) is provided for fixing a laminated steel plate and the magnet forming the rotor. As a result, the end surface of the rotor is formed with a large number of asperities, and the stirring of the working fluid is enhanced by rotating the asperities. Therefore, the oil drops of the refrigeration oil included in the working fluid are divided more finely, and it becomes difficult to separate the refrigeration oil from the working fluid. As a method for separating the stirred and finely divided oil drops from the working fluid, the structure shown in Fig. 10 is used. In this case, however, with regard to the working fluid flowing from the lower space 17 toward the upper space 19 of the rotational motor, this method is effective only for the working fluid passing through the through holes 12c formed in the rotor 12, and it is impossible to separate the oil drops from the working fluid passing through the notches lie of the stator 11 and the gap 18 between the stator 11 and the rotor 12. Further, the oil separating plate 23 is provided on the upper end surface 12b of the rotor. This structure promotes the stirring of the working fluid in the upper space 19 of the rotational motor, and there is a problem that it is more difficult to separate the refrigeration oil in the upper space 19. As another method, volumes of the lower space 17 and the upper space 19 of the rotational motor are increased, and a time during which the working fluid stays in such spaces is lengthened, and separation of the oil drop of the refrigeration oil is promoted by the 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 or the lateral type scroll compressor, but irrespective of a difference between the vertical type and the lateral type or irrespective of a difference of the compressing manners , if the working fluid passes through an end surface of the rotor while a refrigerant discharged from the compression mechanism is discharged from the discharge pipe provided on the container, the same problems mentioned above exist. The above problems are generated irrespective of the particular kinds of the working fluid which are used. However, the problems are particularly severe 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, and an amount of refrigeration oil solved in the working fluid is increased, thereby making it more difficult to separate the oil in the container. 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 rotational motor, capable of reducing the amount of refrigeration oil to be removed 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 having a discharge portion; a compression mechanism disposed in the container and being operable to compress a working fluid; a rotational motor disposed in the container and having a stator and a rotor; a main flowing portion disposed in the container to be isolated from at least one end surface of the rotor and being operable to allow the working fluid to flow from the compression mechanism to the discharge portion. According to this aspect, the main flowing place of the working fluid is isolated from the end surface and thus , turning flow caused by rotation of the rotor is not generated. The finely divided state of the oil drops caused by the stirring of the turning flow is prevented, falling of the oil drops due to gravity from the working fluid is promoted, and the oil separating efficiency can be enhanced. A second aspect of the present invention provides a compressor comprising a container; a compression mechanism disposed in the container; a rotational motor disposed in the container and having a stator and a rotor; a shielding plate disposed to cover at least one end surface of the rotor. According to this aspect, since the shielding plate isolates the end surface, the stirring caused by the turning flow of the working fluid in the main flowing place can be prevented. According to a third aspect of the invention, in the compressor of the second aspect, the shielding plate is mounted on an element other than the rotor. According to this aspect, since elements other than the rotor are not rotated, the shielding plate is not rotated either. Thus , there is a merit that the working fluid is not allowed to generate the turning flow in the main flowing place. According to a fourth aspect of the invention, in the compressor of the third aspect, the shielding plate is mounted on the stator. According to this aspect, by mounting the shielding plate on the stator other than the rotor, the turning flow is not generated, and the end surface of the rotor can completely, be covered with a simple structure. According to a fifth aspect of the invention, in the compressor of the fourth aspect, the stator comprises laminated steel plates and a coil, the shielding plate comprises a steel plate, and the shielding plate is laminated on the stator. According to this aspect, since the shielding plate can be mounted on the stator by means of crimping or welding, the compressor can be produced inexpensively. According to a sixth aspect of the invention, in the compressor of the third aspect, the shielding plate is mounted on the compression mechanism. According to this aspect , the shielding plate is mounted to the compression mechanism other than the rotor, the turning flow is not generated, and the rotational motor can be used as it is without changing the same . According to a seventh aspect of the invention, in the compressor of the sixth aspect, the compression mechanism includes a shaft to which the rotor is fixed and a bearing member which supports the shaft, and the shielding plate is mounted on the bearing member. According to this aspect , the shielding plate is mounted using the bearing member, a column for supporting the shielding plate is unnecessary, and the end surface of the rotor can be covered using a simple structure. According to an eighth aspect of the invention, in the compressor of the seventh aspect, the bearing member includes a projection provided on a side of the rotational motor, and the shielding plate is mounted on a groove formed in an outer peripheral surface of the projection. According to this aspect , by mounting the shielding plate on the groove, the compressor can be assembled without a bolt, and the compressor can be produced inexpensively. According to a ninth aspect of the invention, in the compressor of the second aspect, the stator includes a coil end, and the shielding plate is located inside of the coil end. According to this aspect, if the shielding plate is located inside the coil end, a gap of the side surface (radial direction) between the shielding plate and the end surface of the rotor can be covered with the coil end. The influence of stirring caused by the rotation of the rotor in the main flowing place of the working fluid is reduced and thus, the oil separating efficiency can further be enhanced. According to a tenth aspect of the invention, in the compressor of the third aspect, the shielding plate is mounted on an inner wall of the container. According to this aspect, the shielding plate is mounted on the inner wall of the container other than the rotor, the turning flow is not generated, and the rotational motor and the compression mechanism can be used as they are without changing the rotational motor and the compression mechanism. According to an eleventh aspect of the invention, in the compressor of the third aspect, the compression mechanism includes a shaft to which the rotor is fixed, a bearing member which supports the shaft, and an auxiliary bearing member which supports, together with the bearing member, the shaft from both sides of the shaft on the opposite side of the bearing member with respect to the rotor, and the shielding plate is mounted on the auxiliary bearing member. According to this aspect , the shielding plate is mounted on the auxiliary bearing member other than the rotor, the turning flow is not generated, and the rotational motor can be used as it is without changing the rotational motor. According to a twelfth aspect of the invention, in the compressor of the second aspect, the shielding plate is made of non-magnetic material. According to this aspect, if the shielding plate is made of non-magnetic material, influence exerted on a magnetic circuit of the rotational motor is small, and the oil separating efficiency can be enhanced without deteriorating the efficiency of the rotational motor. According to a thirteenth aspect of the invention, in the compressor of the second aspect, the shielding plate is made of insulative material. According to this aspect , if the shielding plate is made of insulative material, since it is unnecessary to take the electric insulation into account, the shielding plate can be mounted such that it is in contact with the stator or the coil end, and the gap can be eliminated. With this structure having no gap, the influence of the turning flow is prevented from being exerted on the main flowing place of the working fluid, and the influence of the stirring can be reduced, and the oil separating efficiency can be enhanced. According to a fourteenth aspect of the invention, in the compressor of the first aspect, the compression mechanism includes a shaft to which the rotor is fixed and a bearing member which supports the shaft, and the bearing member covers one end surface of the rotor. According to this aspect , since the bearing member is utilized as a member for covering the end surface of the rotor, the end surface can be isolated easily and inexpensively, the falling of the oil drops due to gravity from the working fluid is promoted, and the oil separating efficiency can be enhanced. According to a fifteenth aspect of the invention, in the compressor of the first aspect, the compression mechanism includes a shaft to which the rotor is fixed, a bearing member which supports the shaft, and an auxiliary bearing member which supports, together with the bearing member, the shaft from both sides of the shaft on the opposite side of the bearing member with respect to the rotor, and the auxiliary bearing member covers one end surface of the rotor. According to this aspect , since the auxiliary bearing member is utilized as a member for covering the end sur ace of the rotor, the end surface can be isolated easily and inexpensively, the falling of the oil drops due to gravity from the working fluid is promoted, and the oil separating efficiency can be enhanced. According to a sixteenth aspect of the invention, in the compressor of the first aspect, carbon dioxide is used as the working fluid. According to this aspect, the carbon dioxide as an environment-friendly refrigerant can be used as the working fluid. According to a seventeenth aspect of the invention, in the compressor of the first aspect, the compression mechanism is of a rotary type. According to this aspect , in a rotary compressor in which the working fluid collides directly against the end surface of the rotor, the stirring caused by the turning flow of the working fluid in the flowing place is prevented more remarkably, and the oil separating efficiency can be enhanced. According to an eighteenth aspect of the invention, in the compressor of the first aspect, the compression mechanism is of a scroll type. According to this aspect, in the scroll type compressor, the stirring caused by the turning flow can be prevented, and the oil separating efficiency can be enhanced. A nineteenth aspect of the present invention provides a rotational motor comprising a stator and a rotor; a shielding plate disposed on the stator to cover at least one end surface of the rotor. According to this aspect, since the shielding plate isolates the end surface, the stirring caused by the turning flow of the working fluid in the main flowing place can be prevented. According to a twentieth aspect of the invention, in the rotational motor of the nineteenth aspect, the stator comprises laminated steel plates and a coil, the shielding plate comprises a steel plate, and the shielding plate is laminated on the stator. According to this aspect, since the shielding plate can be mounted on the stator by means of crimping or welding, the compressor can be produced inexpensively. According to a twenty-first aspect of the invention, in the compressor of the second aspect, carbon dioxide is used as the working fluid. According to this aspect, the carbon dioxide as an environment-friendly refrigerant can be used as the working fluid. According to a twenty-second aspect of the invention, in the compressor of the second aspect, the compression mechanism is of a rotary type. According to this aspect, in a rotary compressor in which the working fluid collides directly against the end surface of the rotor, the stirring caused by the turning flow of the working fluid in the flowing place is prevented more remarkably, and the oil separating efficiency can be enhanced. According to a twenty-third aspect of the invention, in the compressor of the second aspect, the compression mechanism is of a scroll type. According to this aspect, in the scroll type compressor, the stirring caused by the turning flow can be prevented, and the oil separating efficiency 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 lateral sectional view of the rotary compressor shown in Fig. 1 taken along the arrow Z-Z in Fig. 1; Fig.3 is a vertical sectional view of a rotary compressor according to a second embodiment of the invention; Fig.4 is a vertical sectional view of a rotary compressor according to a third embodiment of the invention; Fig.5 is a vertical sectional view of a rotary compressor according to a fourth embodiment of the invention; Fig.6 is a vertical sectional view of a scroll compressor according to a fifth embodiment of the invention; Fig.7 is a vertical sectional view of a scroll compressor according to a sixth embodiment of the invention; Fig. 8 is a vertical sectional view of a conventional rotary compressor; Fig. 9 is a vertical sectional view of a conventional scroll compressor; and Fig. 10 is a detailed sectional view of a periphery of an oil separating plate of a conventional compressor.

Detailed Description 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. 8, and the same elements are designated with the same symbols . Fig.1 is a vertical sectional view of a rotary compressor according to the first embodiment of the invention, and Fig.

2 is a lateral sectional view of the rotary compressor shown in Fig. 1 taken along the arrow Z-Z in Fig. 1. The rotary compressor shown in the drawings comprises a container 1 , a compression mechanism disposed at a lower portion in the container 1 , and a rotational motor disposed at an upper portion in the container 1. 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 rotational motor includes a stator 11 which is shrinkage fitted into the container 1, and a rotor which is shrinkage fitted over the shaft 2. The stator 11 is provided with a coil end lie projecting from a lower end surface 11a of the stator 11, and a coil end lid projecting from an upper end surface lib. The stator 11 is formed by laminating steel plates from its lower end surface 11a to its upper end surface lib. The lower end surface 12a and the upper end surface 12b of the rotor 12 can be provided with balancers 12d if necessary. A shielding plate 51 is mounted on the lower end surface 11a of the stator 11 so as to cover the lower end surface 12a of the rotor 12. A plurality of notches lie are provided between an outer peripheral side of the stator 11 and an inner wall of the container 1. The notches lie function as passages for a working fluid. A gap 18 is provided between the stator 11 and the rotor 12. The container 1 is provided at its upper portion with an introduction terminal 13 for energizing the stator 11 from outside of the container 1, an introducing pipe 14 for introducing the working fluid into the suction chamber 9 from the refrigeration cycle, and a discharge pipe 15 for discharging the working fluid into the refrigeration cycle from the container 1. The refrigeration oil is reserved in an oil reservoir 16 formed in a bottom of the container 1. As compared with the conventional rotary compressor shown in Fig. 8, the present embodiment is characterized in that the lower end surface 11a of the stator 11 is located lower than the lower end surface 12a of the rotor 12, and the shielding plate 51 is laminated on the lower end surface 11a of the stator 11 such that the shielding plate 51 covers the lower end surface 12a of the rotor 12. The shielding plate 51 is of a disc-like shape and includes a hole 51a through which the shaft 2 passes, and a notch (not shown) through which the coil end lie passes. The shielding plate 51 is provided at its periphery with a gap 51b between the shielding plate 51 and the inner wall of the container. The operation of the rotary compressor having the above-described structure will be explained. If the stator 11 is energized through the introduction terminal 13 to rotate the rotor 12, the roller 4 is eccentrically rotated by the eccentric portion 2a of the shaft 2, and volumes of the suction chamber 9 and the compression chamber 10 are varied. With this, the working fluid is drawn into the suction chamber 9 from the introducing pipe 14, and is compressed in the compression chamber 10. The compressed working fluid is supplied from the oil reservoir 16, and lubricates a sliding surface of the compression mechanism, and is mixed with oil drops of refrigeration oil which seals the gap, and in this state, the working fluid is injected into the lower space 17 of the rotational motor from the discharge hole 7a formed in the upper bearing member 7. The working fluid injected into the lower space 17 is isolated from the lower end surface 12a of the rotor 12 by the shielding plate 51, and stays in the lower space 17. While the working fluid stays in the lower space 17, a portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 , or drops downward due to gravity and is separated and returns to the oil reservoir 16. Thereafter, the working fluid including oil drops which are not separated passes through the gap 51b and the notches lie from the lower space 17, and passes through the hole 51a and the gap 18 and flows into the upper space 19 of the rotational motor. The working fluid which flows into the upper space 19 from the notches lie flows toward the discharge pipe 15. At that time, a portion of the working fluid passes in the vicinity of the upper end surface 12b of the rotor 12, and produces a turning flow by the rotation of the rotor 12. The working fluid which flows into the upper space 19 from the gap 18 also flows toward the discharge pipe 15 but at that time, the working fluid produces the turning flow by the rotation of the rotor 12. On the other hand, a portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 by the centrifugal force of the turning flow, or drops due to gravity, and is separated from the working fluid, and returns to the oil reservoir 16 along the inner wall of the container 1 or a wall surface of the stator 11. The working fluid including oil drops which are not yet separated is discharged from the discharge pipe 15. With such a structure, the lower end surface 12a of the rotor 12 is separated from the lower space 17 of the rotational motor and the main flowing place of the working fluid from the instant when the working fluid is discharged from the discharge hole 7a and to the instant when the working fluid reaches the discharge pipe 15 can be isolated from the lower end surface 12a of the rotor 12 , the shielding plate 51 is fixed to a location other than the rotor 12 and is not rotated, and the turning flow is not generated in the lower space 17 which is the main flowing place of the working fluid. The aforementioned portion in the container 1 though which the working fluid flows from the instant when the working fluid is discharged from the hole 7a and to the instant when the working fluid reaches the discharge pipe 15 is a main flowing portion of the compressor. According to the rotary compressor of this embodiment, in the lower space 17, a stirring caused by the turning flow itself and a stirring caused by rotation of asperities such as the balancer 12d of the lower end surface 12a of the rotor 12 can be prevented, and the oil drops of the refrigeration oil can be prevented from being finely divided. Therefore, the effect that the oil drops fall downward due to gravity and are separated while the working fluid stays in the lower space 17 is promoted, and the oil separating efficiency can be enhanced. In this embodiment, since the shielding plate 51 is disposed on the lower end surface 11a of the stator 11, there is a merit that the lower end surface 12a side of the rotor 12 can be covered by the shielding plate 51 and the inner surface of the stator 11 using a simple structure. The shielding plate 51 need not completely cover the lower end surface 12a of the rotor 12, and the shielding plate may be partially provided with a hole or a notch, or the shielding plate may cover only a portion of the lower end surface 12a. Even with such a structure, the influence of the stirring can be reduced, and the oil separating efficiency can be enhanced. When the shielding plate 51 is formed of a steel plate. it is laminated on the lower end surface 11a of the laminated steel plates of the stator 11, the shielding plate 51 and the laminated steel plates of the stator 11 are crimped or welded, and the shielding plate 51 can be fixed and produced inexpensively. If the shielding plate 51 is made of a non-magnetic material, the shielding plate 51 does not significantly affect the magnetic circuit of the rotational motor so much, and the oil separating efficiency can be enhanced without deteriorating the efficiency of the rotational motor. If the shielding plate 51 is made of insulative resin or insulator such as ceramic, the shielding plate 51 can be disposed such that it is in contact with the coil end lie of the stator 11. Therefore, it is unnecessary to provide a gap between the shielding plate 51 and the coil end lie for electric insulation. Therefore, the influence of rotation of the lower end surface 12a can be prevented from being exerted on the lower space 17 from the slight gap provided between the coil end lie and the shielding plate 51, and the influence of stirring can be reduced, and the oil separating efficiency can be enhanced. Although the shielding plate 51 is provided on the lower end surface 11a of the stator 11 in this embodiment, the shielding plate 51 may be provided on a lower end surface of the coil end lie of the stator 11 other than the lower end surface 11a, and if the lower end surface 12a of the rotor 12 is covered, the same effect can be obtained. The vertical rotary compressor is explained in this embodiment irrespective of the difference between the vertical type and the lateral type and irrespective of the difference of compressing manners. If the main flowing place at which the refrigerant discharged from the compression mechanism is discharged from the discharge pipe 15 provided on the container 1 passes in the vicinity of the rotor 12, the same effect can be obtained. In a compressor in which the working fluid injected from the discharge hole 7a collides directly against the lower end surface 12a of the rotor 12 like the conventional rotary compressor, the lower end surface 12a of the rotor 12 is covered with the shielding plate 51, and the effect for preventing the stirring is exhibited more remarkably. A compressor of a second embodiment of the present invention is similar to the rotary compressor of the first embodiment explained using Fig. 1 and the conventional rotary compressor explained using Fig. 8. The same elements are designated with the same symbols . Fig.3 is a vertical sectional view of a rotary compressor according to the second embodiment of the invention. The rotary compressor of the second embodiment is different from the conventional rotary compressor shown in Fig. 8 in that the upper end surface lib of the stator 11 is located higher than the upper end surface 12b of the rotor 12, the shielding plate 52 is superposed on the upper end surface lib of the stator 11, and the shielding plate 52 covers the upper end surface 12b of the rotor 12. The shielding plate 52 is of a disk-like shape having a hole 52a through which the shaft 2 penetrates, and a notch (not shown) through which the coil end lid penetrates. The shielding plate 52 is provided at its periphery with a gap 52b formed between the shielding plate 52 and the inner wall of the container 1. The operation of the rotary compressor having the above-described structure will be explained based on the flow of the working fluid and the oil. The working fluid compressed by the compression mechanism is injected into the lower space 17 from the discharge hole 7a. This injected working fluid produces the turning flow by the influence of the rotation of the rotor 12. A portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 by the centrifugal force of the turning flow, or drops due to gravity and is separated from the working fluid, and returns to the oil reservoir 16 along the inner wall of the container 1 or the wall surface of the stator 11. Thereafter, the working fluid passes through the notches lie and the gap 52b from the lower space 17, passes through the gap 18 and the hole 52a and flows into the upper space 19. This working fluid is isolated from the upper end surface 12b of the rotor 12 by the shielding plate 52 and stays in the upper space 19. While the working fluid stays in the upper space 19, a portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 , or drops downward due to gravity and returns into the oil reservoir 16. Then, the working fluid flows toward the discharge pipe 15. With such a structure, the upper end surface 12b of the rotor 12 is separated from the upper space 19 of the rotational motor, and the main flowing place of the working fluid from the instant when the working fluid is discharged from the discharge hole 7a and to the instant when the working fluid reaches the discharge pipe 15 can be isolated from the upper end surface 12b of the rotor 12 , the shielding plate 51 is fixed to a location other than the rotor 12 and is not rotated, and the turning flow is not generated in the upper space 19 which is the main flowing place of the working fluid. According to the rotary compressor of this embodiment, in the upper space 19, a stirring caused by the turning flow itself and a stirring caused by rotation of asperities such as the balancer 12d of the upper end surface 12b of the rotor 12 can be prevented, and the oil drops of the refrigeration oil can be prevented from being finely divided. Therefore, the effect that the oil drops fall downward due to gravity and are separated while the working fluid stays in the upper space 19 is promoted, and the oil separating efficiency can be enhanced. This second embodiment is different from the first embodiment only in that the shielding plate 51, 52 is mounted on the lower end surface 11a or the upper end surface lib, and the same effect as that of the first embodiment can be obtained on the side of the upper end surface lib of the stator 11. If the compressor has a combination of the shielding plate 52 on the side of the upper end surface lib of the stator 11 and the shielding plate 51 on the side of the lower end surface 11a of the first embodiment, the oil separating efficiency is further enhanced. A compressor of a third embodiment of the present invention is similar to the rotary compressor of the first embodiment explained using Fig. 1. The same elements are designated with the same symbols . Explanation of the same structure and operation will be omitted. Fig. 4 is a vertical sectional view of the rotary compressor according to the third embodiment of the invention. The rotary compressor of the third embodiment is different from the conventional rotary compressor shown in Fig. 8 in that a projection 7b of the upper bearing member 7 projects to a location near the lower end surface 12a of the rotor 12, a shielding plate 53 is disposed in the vicinity of a tip end of the projection 7b, thereby covering the lower end surface 12a of the rotor 12. The shielding plate 53 is made of resin and is of a disk-like shape. The shielding plate 53 is provided at its central portion with a hole (not shown) through which the projection 7b of the upper bearing member 7 penetrates . The shielding plate 53 is mounted on and fixed to a groove 7c formed in the projection 7b. An outer diameter of the shielding plate 53 is substantially the same as an outer diameter of the rotor 12, and the shielding plate 53 is disposed in an inner space of the coil end lie. The operation of the rotary compressor having the above-described structure will be explained based on the flow of the working fluid and the oil. The working fluid compressed by the compression mechanism is injected into the lower space 17 from the discharge hole 7a. This injected working fluid is isolated from the lower end surface 12a of the rotor 12 by the shielding plate 53 and stays in the lower space 17. While the working fluid stays in the lower space 17 , a portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 or drops downward due to gravity and is separated from the working fluid, and returns to the oil reservoir 16. Thereafter, the working fluid flows into the upper space 19 from the lower space 17 through the notches lie and the gap 18. This flowing working fluid produces the turning flow by the influence of the rotation of the rotor 12. A portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 by the centrifugal force of the turning flow, or drops due to gravity and is separated from the working luid, and returns to the oil reservoir 16 along the inner wall of the container 1 or the wall surface of the stator 11. Then, the working fluid flows toward the discharge pipe 15. With such a structure, the lower end surface 12a of the rotor 12 is separated from the lower space 17 of the rotational motor, and the main flowing place of the working fluid from the instant when the working fluid is discharged from the discharge hole 7a to the instant when the working fluid reaches the discharge pipe 15 can be isolated from the lower end surface 12a of the rotor 12 , the shielding plate 53 is fixed to a location other than the rotor 12 and is not rotated, and the turning flow is not generated in the lower space 17. According to the rotary compressor of this embodiment, in the lower space 17, a stirring caused by the turning flow itself and the influence of stirring caused by rotation of asperities such as the balancer 12d of the lower end surface 12a of the rotor 12 can be reduced, and the oil drops of the refrigeration oil can be prevented from being finely divided. Therefore, the effect that the oil drops fall downward due to gravity and are separated while the working fluid stays in the lower space 17 is promoted, and the oil separating efficiency can be enhanced. In this embodiment, since the shielding plate 53 is mounted on the compression mechanism, there is a merit that a rotational motor which was used in a conventional compressor can be utilized as it is. Further, since the shielding plate 53 is mounted on the projection 7b of the compression mechanism, it is unnecessary to prepare a new support member such as a column, and the shielding plate 53 can be disposed in the vicinity of the lower end surface 12a of the rotor 12 with a simple structure. Since the shielding plate 53 is mounted on the groove 7c formed in the outer periphery of the projection 7b, the compressor can be assembled without using a fixing member such as a bolt, and the compressor can be produced inexpensively. Since the shielding plate 53 is disposed inside the coil end lie, the gap of the side surface between the shielding plate 53 and the lower end surface 12a of the rotor 12 can be covered with the coil end lie, the influence of stirring caused by the rotation of the rotor 12 with respect to the lower space 17 can be reduced, and the oil separating efficiency can further be enhanced. Although the shielding plate is made of resin in the third embodiment, even if any material is used, the oil separating efficiency reducing effect is the same. However, since the shielding plate is provided in the vicinity of the coil end lie, it is preferable that the shielding plate is made of an insulative material for enhancing the reliability with respect to leakage of electricity. In view of efficiency of the rotational motor, a non-magnetic material which does not affect a magnetic circuit is preferable used as the shielding plate . A compressor of a fourth embodiment of the present invention is similar to the rotary compressor of the first embodiment and the conventional rotary compressor. The same elements are designated with the same symbols. Explanation of the same structure and operation will be omitted. Fig.5 is a vertical sectional view of a rotary compressor according to the fourth embodiment of the invention. The rotary compressor of the fourth embodiment is different from the conventional rotary compressor shown in Fig. 8 in that a shielding plate 54 for covering the lower end surface 12a of the rotor 12 is provided below the coil end lie at the lower end of the stator 11, and the lower space 17 as the main flowing place of the working fluid is isolated from the lower end surface 12a by this shielding plate 54. Further, a shielding plate 55 for covering the upper end surface 12b of the rotor 12 is provided above the coil end lid at the upper end of the stator 11, and the upper space 19 as the main flowing place of the working fluid is isolated from the upper end surface 12b by this shielding plate 55. The shielding plates 54 and 55 are fixed to the inner wall of the container 1. The shielding plate 54 is provided at its central portion with a hole 54a through which the projection 7b of the upper bearing member 7 penetrates . The shielding plate 54 is also provided at its peripheral portion with a notch 54b which brings the lower space 17 and the notches lie of the stator 11 into communication with each other. The shielding plate 55 is provided at its peripheral portion with a notch 55a which brings the notches lie of the stator 11 and the upper space 19 into communication with each other. The operation of the rotary compressor having the above-described structure will be explained based on the flow of the working fluid and the oil. The working fluid compressed in the compression mechanism is injected into the lower space 17 from the discharge hole 7a. This injected working fluid is isolated from the lower end surface 12a of the rotor 12 by the shielding plate 54 and stays in the lower space 17. While the working fluid stays in the lower space 17 , a portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 , or drops downward due to gravity and is separated from the working fluid, and returns to the oil reservoir 16. Thereafter, the working fluid flows into the upper space 19 from the lower space 17 through the notch 54b, the hole 54a, the notches lie, the gap 18 and the notch 55a. This flowing working fluid is isolated from the upper end surface 12b of the rotor 12 by the shielding plate 55 and stays in the upper space 19. While the working fluid stays in the upper space 19, a portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 , or drops downward due to gravity and is separated from the working fluid, and returns to the oil reservoir 16 along the inner wall of the container 1 or the wall surface of the stator 11. Then, the working fluid flows toward the discharge pipe 15. With such a structure, like the first embodiment, the lower end surface 12a of the rotor 12 is separated from the lower space 17 of the rotational motor, and the main flowing place of the working fluid from the instant when the working fluid is discharged from the discharge hole 7a to the instant when the working fluid reaches the discharge pipe 15 can be isolated from the lower end surface 12a of the rotor 12, the shielding plate 54 is fixed to a location other than the rotor 12 and is not rotated, and the turning flow is not generated in the lower space 17. Further, like the second embodiment, the upper end surface 12b of the rotor 12 is separated from the upper space 19 of the rotational motor, and the main flowing place of the working fluid from the instant when the working fluid is discharged from the discharge hole 7a to the instant when the working fluid reaches the discharge pipe 15 can be isolated from the upper end surface 12b of the rotor 12, and the shielding plate 55 is fixed to a location other than the rotor 12 and is not rotated, and the turning flow is not generated in the upper space 19. According to the rotary compressor of this embodiment, a stirring caused by the turning flow itself and a stirring caused by rotation of asperities such as the balancer 12d of the lower end surface 12a of the rotor 12 can be prevented, and the oil drops of the refrigeration oil can be prevented from being finely divided. Therefore, the effect that the oil drops fall downward due to gravity and are separated while the working fluid stays in the lower space 17 is promoted, and the oil separating efficiency can be enhanced. Further, a stirring caused by the turning flow itself and a stirring caused by rotation of asperities such as the balancer 12d of the upper end surface 12b of the rotor 12 can be prevented, and the oil drops of the refrigeration oil can be prevented from being finely divided. Therefore, the effect that the oil drops fall downward due to gravity and are separated while the working fluid stays in the upper space 19 is promoted, and the oil separating efficiency can be enhanced. In this embodiment, since the shielding plates 54 and 55 are mounted on the inner wall of the container 1 , there is a merit that a rotational motor and a compression mechanism which were used in a conventional compressor can be utilized as they are. The compressor may be provided with any one of the shielding plate 54 and the shielding plate 55, and the oil separating efficiency is enhanced on the side where the shielding plate of the rotational motor is provided of course. If the shielding plate 51 of the first embodiment for covering the lower end surface 12a of the rotor 12 , the shielding plate 53 of the third embodiment, and the shielding plate 55 of the fourth embodiment for covering the upper end surface 12b of the rotor 12 are combined, the oil separating efficiency of the rotary compressor of the first or third rotary compressor can further be enhanced. A compressor of a fifth embodiment of the present invention is a scroll compressor, and is similar to the conventional scroll compressor explained using Fig. 9. The same elements are designated with the same symbols. Fig.6 is a vertical sectional view of a scroll compressor according to the fifth embodiment of the invention. The scroll compressor shown in the drawing comprises a container 31 , a compression mechanism disposed on the right side in the container 31, and a rotational motor disposed on the left side. The compression mechanism comprises a shaft 32 which can rotate around a center axis L and which includes an eccentric portion 32a, a stationary scroll 33 having a spiral lap 33a such as an involute and a discharge hole 33b, a moving scroll 34 which has a spiral lap 34a and is disposed such that laps 33a and 34a mesh with each other and are opposed to the stationary scroll 33, and which turns as the eccentric portion 32a eccentrically rotates, an Oldham ring 35 for preventing the moving scroll 34 from rotating, and a bearing member 36 which includes a projection 36a and a discharge hole 36c and which supports the shaft 32. A plurality of suction chambers 37 and compression chambers 38 are formed between the stationary scroll 33 and the moving scroll 34. The rotational motor includes a stator 39 which is shrinkage fitted into the container 31 and a rotor 40 which is shrinkage fitted over the shaft 32. The stator 39 is provided with a coil end 39c projecting from a right end surface 39a of the stator 39 and a coil end 39d projecting from a left end surface 39b of the stator 39. The stator 39 is formed by laminating steel plates from its right end surface 39a to the left end surface 39b. The right end surface 40a and the left end surface 40b of the rotor 40 can be provided with balancers 40c if necessary. On the other hand, a shielding plate 56 for covering the right end surface 40a of the rotor 40 is mounted on the projection 36a of the bearing member 36. An auxiliary bearing member 41 which supports the shaft 32 is disposed on the left side of the rotational motor on the opposite side of the bearing member 36 with respect to the rotor 40. The auxiliary bearing member 41 has a projection 41a, and a shielding plate 57 is mounted on the projection 41a such as to cover the left end surface 40b of the rotor 40. A plurality of notches 39e which function as passages of the working fluid is provided between the outer peripheral side of the stator 39 and the inner wall of the container 31. A gap 48 is provided between the stator 39 and the rotor 40. The auxiliary bearing member 41 is provided with a hole 41c. The wall of the container 31 is provided with an introduction terminal 42 for energizing the stator 39 from an outside of the container 1, an introducing pipe 43 for introducing the working fluid into the suction chambers 37 from the refrigeration cycle, and a discharge pipe 44 for discharging the working fluid into the refrigeration cycle from the container 31. The refrigeration oil is reserved in an oil reservoir 45 formed in a bottom of the container 31, the refrigeration oil is drawn up from the oil reservoir 45 by an oil supply pump 46, and the refrigeration oil is supplied to the compression mechanism from an oil-supply hole (not shown) of the shaft 32. As compared with the conventional scroll compressor shown in Fig. 9, the scroll compressor of this embodiment is characterized in that by disposing the shielding plate 56 in the vicinity of the tip end of the projection 36a of the bearing member 36 which projects to the location near the right end surface 40a of the rotor 40, the shielding plate 56 covers the right end surface 40a of the rotor 40. Further, by disposing the shielding plate 57 in the vicinity of the tip end of the projection 41a of the auxiliary bearing member 41 which projects to the location near the left end surface 40b of the rotor 40, the shielding plate 57 covers the left end surface 40b of the rotor 40. The shielding plate 56 is made of resin and is of a disk-like shape. The shielding plate 56 is provided with a hole (not shown) through which the projection 36a of the bearing member 36 penetrates. The shielding plate 56 is mounted on and fixed to a groove 36b formed in an outer peripheral surface of the projection 36a. An outer diameter of the shielding plate

56 is substantially the same as an outer diameter of the rotor 40, and the shielding plate 56 is disposed in an inside space of the coil end 39c. The shielding plate 57 is made of resin and is of a disk-like shape. The shielding plate 57 is provided with a hole (not shown) through which the projection 41a of the bearing member 41 penetrates . The shielding plate 57 is mounted on and fixed to a groove 41b formed in an outer peripheral surface of the projection 41a. An outer diameter of the shielding plate

57 is substantially the same as an outer diameter of the rotor 40, and the shielding plate 57 is disposed in an inside space of the coil end 39c. The operation of the scroll compressor having the above-described structure will be explained. If the stator 39 is energized through the introduction terminal 42 to rotate the rotor 40, the moving scroll 34 turns, and volumes of the suction chambers 37 and the compression chambers 38 formed between the stationary scroll 33 and the laps 33a and 34a of the moving scroll 34 are varied. With this, the working fluid is sucked by the suction chambers 37 from the introducing pipe 43 and is compressed in the compression chambers 38. The compressed working fluid is supplied from the oil reservoir 45 to lubricate a sliding surface of the compression mechanism, and is mixed with oil drops of the refrigeration oil which seals the gap and in this state, the working fluid is injected into the right space 47 of the rotational motor from the discharge holes 33b and 36c. The working fluid injected into the right space 47 is isolated from the right end surface 40a of the rotor 40 and stays in the right space 47. While the working fluid stays in the right space 47 , a portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 or drops downward due to gravity and is separated, and returns into the oil reservoir 45. Thereafter, the working fluid including oil drops which are not yet separated passes through the notches 39e, the gap 48 and the hole 41c from the right space 47, and flows into the left space 49 of the rotational motor. The working fluid which flowed into the left space 49 is isolated from the left end surface 40b of the rotor 40 by the shielding plate 57, and stays in the left space 49. While the working fluid stays in the left space 49, a portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 or drops downward due to gravity and is separated, and returns into the oil reservoir 45. The working fluid including oil drops which are not yet separated is discharged from the discharge pipe 44. With the above-described structure, the right end surface 40a of the rotor 40 is separated from the right space 47, and the main flowing place of the working fluid from the instant when the working fluid is discharged from the discharge hole 36c to the instant when the working fluid reaches the discharge pipe 44 can be isolated from the right end surface 40a of the rotor 40, the shielding plate 56 is fixed to a location other than the rotor 40 and is not rotated, and the turning flow is not generated in the right space 47. In this embodiment, the shielding plate 57 is disposed in the vicinity of the left end surface 40b of the rotor 40 using the auxiliary bearing member 41 which is a mechanism peculiar to the conventional scroll compressor. With this structure, the left end surface 40b of the rotor 40 is separated from the left space 49, the main flowing place of the working fluid from the instant when the working fluid is discharged from the discharge hole 36c to the instant when the working fluid reaches the discharge pipe 44 can be isolated from the left end surface 40b of the rotor 40, the shielding plate 57 is fixed to a location other than the rotor 40 and is not rotated, and the turning flow is not generated in the left space 49. Therefore, according to the scroll compressor of this embodiment, a stirring caused by the turning flow itself and a stirring caused by rotation of asperities such as the balancer 40c of the right end surface 40a of the rotor 40 can be prevented, and the oil drops of the refrigeration oil can be prevented from being finely divided. Therefore, the effect that the oil drops downward due to gravity and are separated while the working fluid stays in the right space 47 is promoted, and the oil separating efficiency can be enhanced. In the left space 49 also, a stirring caused by the turning flow itself and a stirring caused by rotation of asperities such as the balancer 40c of the left end surface 40b of the rotor 40 can be prevented, and the oil drops of the refrigeration oil can be prevented from being finely divided. Therefore, the effect that the oil drops downward due to gravity and are separated while the working fluid stays in the left space 49 is promoted, and the oil separating efficiency can be enhanced. In this embodiment, since the shielding plates 56 and 57 are mounted on the bearing member 36 or the auxiliary bearing member 41 which are portions of the compression mechanism, there is a merit that a rotational motor which was used in a conventional compressor can be used as it is. Since the shielding plate 56 is mounted on the projection 36a of the bearing member 36 and the shielding plate 57 is mounted on the projection 41a of the auxiliary bearing member 41, it is unnecessary to constitute a new support portion such as a column, and the shielding plates 56 and 57 can be disposed in the vicinity of the right end surface 40a and the left end surface 40b of the rotor 40 with a simple structure. Since the shielding plates 56 and 57 are mounted on the grooves 36b and 41b in the outer periphery of the projections 36a and 41a, the compressor can be assembled without using a fixing member such as a bolt, and the compressor can be produced inexpensively. Since the shielding plates 56 and 57 are disposed inside of the coil ends 39c and 39d, the gap of the side surface between the shielding plates 56 and 57 and the end surfaces 40a and 40b can be covered with the coil ends 39c and 39d, the influence of stirring caused by the rotation of the rotor 40 with respect to the right space 47 and the left space 49 can be reduced, and the oil separating efficiency can further be enhanced. The compressor may be provided with any one of the shielding plates 56 and 57, and the oil separating efficiency is enhanced on the side where the shielding plate of the rotational motor is provided. A compressor of a sixth embodiment of the present invention is similar to the scroll compressor of the fifth embodiment explained using Fig. 6 and the conventional scroll compressor explained using Fig. 9. The same elements are designated with the same symbols. Explanation of the same structure and operation will be omitted. Fig.7 is a vertical sectional view of a scroll compressor according to the sixth embodiment of the invention. The scroll compressor of this embodiment is different from the conventional scroll compressor shown in Fig. 9 in that the diameter of the projection 36d of the bearing member 36 is substantially the same as the outer diameter of the rotor 40, and the projection 36d projects to the location in the vicinity of the right end surface 40a of the rotor 40 and with this structure, the shielding plate covers the right end surface 40a of the rotor 40. Further, the diameter of the projection 41d of the auxiliary bearing member 41 is substantially the same as the outer diameter of the rotor 40, the projection 41d projects to the location in the vicinity of the left end surface 40b of the rotor 40 and with this structure, the shielding plate covers the left end surface 40b of the rotor 40. The operation of the rotary compressor having the above-described structure will be explained based on the flow of the working fluid and the oil. The working fluid compressed in the compression mechanism is injected into the right space 47 from the discharge holes 33b and 36c. This injected working fluid is isolated from the right end surface 40a of the rotor 40 by the projection 36d of the bearing member 36 as the shielding plate and stays in the right space 47. While the working fluid stays in the right space 47, a portion of the oil drops included in the working fluid attaches to the inner wall of the container 1, or drops downward due to gravity and is separated from the working fluid, and returns to the oil reservoir 45. Thereafter, the working fluid flows into the left space 49 from the right space 47 through the notches 39e, the gap 48 and the hole 41c formed in the auxiliary bearing member 41. This working fluid is isolated from the left end surface 40b of the rotor 40 by the projection 41d of the auxiliary bearing member 41 and stays in the left space 49. While the working fluid stays in the left space 49, a portion of the oil drops included in the working fluid attaches to the inner wall of the container 1 , or drops downward due to gravity and is separated from the working fluid, and returns to the oil reservoir 45. Then, the working fluid flows toward the discharge pipe 44. With this structure, like the fifth embodiment, the right end surface 40a of the rotor 40 is separated from the right space 47 , the main flowing place of the working fluid from the instant when the working fluid is discharged from the discharge hole 36c to the instant when the working fluid reaches the discharge pipe 44 can be isolated from the right end surface 40a of the rotor 40, and the turning flow is not generated in the right space 47. Further, the left end surface 40b of the rotor 40 is separated from the left space 49, the main flowing place of the working fluid from the instant when the working fluid is discharged from the discharge hole 36c to the instant when the working fluid reaches the discharge pipe 44 can be isolated from the left end surface 40b of the rotor 40, and the turning flow is not generated in the left space 49. Therefore, according to the scroll compressor of this embodiment, in the right space 47 and the left space 49, a stirring caused by the turning flow itself, a stirring caused by rotation of asperities such as the balancer 40c of the right end surface 40a of the rotor 40 , and a stirring caused by rotation of asperities such as the balancer 40c of the left end surface 40b of the rotor 40 can be prevented, and the oil drops of the refrigeration oil can be prevented from being finely divided. Therefore, the effect that the oil drops downward due to gravity and are separated while the working fluid stays in the right space 47 and the left space 49 is promoted, and the oil separating efficiency can be enhanced. In the scroll compressor of this embodiment, the end surfaces 40a and 40b of the rotor 40 are covered only by changing the shapes of the projection 36d of the bearing member 36 and the projection 41d of the auxiliary bearing member 41 without adding another shielding plate and thus , the structure is simple and cost is low. The compressor may be provided with any one of the projection 36d of the bearing member 36 and the projection 4Id of the auxiliary bearing member 41 as a shielding plate, and the oil separating efficiency is enhanced on the side where the shielding plate of the rotational motor is used. When carbon dioxide is used as the working fluid, the amount of refrigeration oil which is dissolved in the working fluid is increased, but if the carbon dioxide is combined with the compressor of any of the first to sixth embodiments, the end surface of the rotor is covered, and the stirring can be prevented. Therefore, the oil separating efficiency of the refrigeration oil can be enhanced. With this, there is a merit that the reliability of the compressor and the efficiency of the refrigeration cycle using the compressor can be enhanced, and the carbon dioxide as an environment-friendly refrigerant can be used. As described above, according to the present invention, the shielding plate is provided in the vicinity of the end of the rotor of the rotational motor, the main flowing place of working fluid in the container from the instant when the working fluid is discharged from the compression mechanism to the instant when the working fluid reaches the discharge pipe is isolated from both end surfaces of the rotor in the lower space and the upper space of the rotational motor in the case of the vertical type compressor, and in the right space and the left space of the motor in the case of the lateral type compressor. With this , a stirring caused by the turning flow generated by the rotation of the rotor, and a stirring caused by the rotation of asperities such as the balancer are suppressed, and the oil drops of the refrigeration oil mixed into the working fluid are prevented from being stirred and finely divided. With this , the effect that the oil drops fall by the gravity and are separated from the working fluid while the working fluid stays in the lower space and the upper space, or the right space and the left space of the rotational motor is promoted, and the oil separating efficiency can be enhanced, and the reliability and efficiency of the compressor and the refrigeration cycle using the compressor can be enhanced.

Industrial Applicability As described above, the present invention is 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.

Claims

1 . A compressor comprising : a container having a discharge portion; a compression mechanism disposed in said container and being operable to compress a working fluid; a rotational motor disposed in said container and having a stator and a rotor; a main flowing portion disposed in said container to be isolated from at least one end surface of said rotor and being operable to allow the working fluid to flow from said compression mechanism to said discharge portion.

2. A compressor comprising: a container; a compression mechanism disposed in said container; a rotational motor disposed in said container and having a stator and a rotor; a shielding plate disposed to cover at least one end surface of said rotor.

3. A compressor according to claim 2, wherein said shielding plate is mounted on an element other than said rotor.

4. A compressor according to claim 3, wherein said shielding plate is mounted on said stator.

5. A compressor according to claim 4, wherein said stator comprises laminated steel plates and a coil, said shielding plate comprises a steel plate, and said shielding plate is laminated on said stator.

6. A compressor according to claim 3, wherein said shielding plate is mounted on said compression mechanism.

7. A compressor according to claim 6, wherein said compression mechanism includes a shaft to which said rotor is fixed and a bearing member which supports said shaft, and said shielding plate is mounted on said bearing member.

8. A compressor according to claim 7, wherein said bearing member includes a projection provided on a side of said rotational motor, and said shielding plate is mounted on a groove formed in an outer peripheral surface of said projection.

9. A compressor according to claim 2, wherein said stator includes a coil end, and said shielding plate is located inside of said coil end.

10. A compressor according to claim 3, wherein said shielding plate is mounted on an inner wall of said container.

11. A compressor according to claim 3, wherein said compression mechanism includes a shaft to which said rotor is fixed, a bearing member which supports said shaft, and an auxiliary bearing member which supports, together with said bearing member, said shaft from both sides of said shaft on the opposite side of said bearing member with respect to said rotor, and said shielding plate is mounted on said auxiliary bearing member.

12. A compressor according to claim 2, wherein said shielding plate is made of non-magnetic material.

13. A compressor according to claim 2, wherein said shielding plate is made of insulative material.

14. A compressor according to claim 1, wherein said compression mechanism includes a shaft to which said rotor is fixed and a bearing member which supports said shaft, and said bearing member covers one end surface of said rotor.

15. A compressor according to claim 1, wherein said compression mechanism includes a shaft to which said rotor is fixed, a bearing member which supports said shaft, and an auxiliary bearing member which supports, together with said bearing member, said shaft from both sides of said shaft on the opposite side of said bearing member with respect to said rotor, and said auxiliary bearing member covers one end surface of said rotor.

16. A compressor according to claim 1, wherein carbon dioxide is used as the working fluid.

17. A compressor according to claim 1, wherein said compression mechanism is of a rotary type.

18. A compressor according to claim 1, wherein said compression mechanism is of a scroll type.

19. A rotational motor comprising: a stator and a rotor; and a shielding plate disposed on said stator to cover at least one end surface of said rotor.

20. A rotational motor according to claim 19, wherein said stator comprises laminated steel plates and a coil, said shielding plate comprises a steel plate, and said shielding plate is laminated on said stator.

21. A compressor according to claim 2, wherein carbon dioxide is used as the working fluid.

22. A compressor according to claim 2, wherein said compression mechanism is of a rotary type.

23. A compressor according to claim 2, wherein said compression mechanism is of a scroll type.