Patent Publication Number: US-9885357-B2

Title: Hermetic compressor and vapor compression-type refrigeration cycle device including the hermetic compressor

Description:
TECHNICAL FIELD 
     The present invention relates to a hermetic compressor, and a vapor compression-type refrigeration cycle device including the hermetic compressor. In particular, the present invention relates to a hermetic compressor excellent in oil separation effect, and a vapor compression-type refrigeration cycle device including the hermetic compressor. 
     Citation List 
     Patent Literature 
     Patent Literature 1: Japanese Patent No. 3925392 
     Patent Literature 2: Japanese Unexamined Utility Model Application Publication No. Hei 5-61487 
     Patent Literature 3: Japanese Unexamined Patent Application Publication No. 2009-264175 
     BACKGROUND ART 
     Hitherto, in a refrigerant compressor used in vapor compression-type refrigeration cycle devices (such as heat pump equipment and refrigeration cycle equipment), a rotational force of an electric motor is transmitted to a compression mechanism by a drive shaft so that refrigerant gas is compressed. In such a refrigerant compressor, the refrigerant gas compressed by the compression mechanism is discharged into a hermetic container, moved from a space below the electric motor into a space above the same through electric motor unit gas passages, and then discharged into a refrigerant circuit on an outside of the hermetic container. At this time, lubricating oil supplied to the compression mechanism and mixed with the refrigerant gas is discharged to the outside of the hermetic container. Hitherto, there is a problem in that an increase in amount of the oil to be discharged into the refrigerant circuit causes degradation in performance of a heat exchanger. In addition, there is another problem in that a decrease in amount of the oil stored in the hermetic container causes insufficient lubrication, resulting in degradation in reliability of the refrigerant compressor. 
     In recent years, there have been promoted development of refrigerant compressors having smaller sizes, and conversion to use of alternative refrigerants (including natural refrigerant) having a lower environmental load. Under the circumstances, advanced technology for separating the oil in the hermetic container has been demanded. However, how the refrigerant and the lubricating oil flow and how the oil separation occurs during high speed rotation of the electric motor in the hermetic container are significantly complicated, and observation experiments in the hermetic container under high pressure are not easy. Thus, there are a large number of unknown factors, and a large number of technical problems have not yet been solved. 
     In the high-pressure shell type scroll compressor disclosed in Patent Literature 1, sucked refrigerant is compressed by the compression mechanism arranged on an upper side in the hermetic container, and once caused to flow down to an oil reservoir at a bottom of the hermetic container. After that, the refrigerant is caused to flow up from a space below the electric motor to a space above the same through electric motor gas passages, and then discharged as high pressure gas through a discharge pipe of the compressor. The high-pressure shell type scroll compressor disclosed in Patent Literature 1 includes a fan arranged on an upper portion of a rotator of the electric motor, and partition walls for separating a stator side of the electric motor and a rotator side of the electric motor from each other above the fan. Then, the refrigerant and the lubricating oil are separated from each other by using a centrifugal force generated by rotation of the fan and by using pressure resistance generated through gaps between the partition walls. The lubricating oil is prevented from flowing directly into the discharge pipe without being separated from the refrigerant, in other words, the lubricating oil is prevented from flowing out from the hermetic container. 
     Further, in Patent Literature 2, there is disclosed an oil separation device for a hermetic electric compressor including: an electric component housed in an upper portion of a hermetic container; a compression component that is driven by the electric component; an oil separation plate arranged to face an upper end ring of a rotor of the electric component across a predetermined clearance; and stirring vanes arranged upright to the oil separation plate, in which the stirring vanes are arranged upright only to a lower surface of the oil separation plate. 
     Effects of improving an oil separation condition in the hermetic container of the compressor by using the fan and the partition walls in Patent Literature 1 and the oil separation plate and the stirring vanes in Patent Literature 2 are generally observed. 
     Further, in recent years, by using significantly advanced three-dimensional fluid simulation technology, flow conditions of the refrigerant and the lubricating oil in the hermetic container of the compressor can be visualized. Thus, new findings are obtained. Specifically, in Patent Literature 3, there is disclosed a refrigerant compressor in which an increase in head pressure that is generated near a leading end in a rotation direction of an upper balance weight at an upper end of the rotator of the electric motor arranged in the hermetic container is used to form an oil return passage from a vicinity of a leading end portion toward a lower end so that high density lubricating oil that appears around the rotator is returned below the electric motor, to thereby prevent the oil from flowing out. 
     SUMMARY OF INVENTION 
     Technical Problem 
     In general, to provide a high-performance centrifugal air-sending device, as described in Non Patent Literature 1, the shape of the impeller itself, the shape of the passage of flow extending into the impeller, the shape of the passage of flow extending outside of the impeller, and the like need to be theoretically designed. 
     However, in Patent Literatures 1 and 2, no theoretical design methods are disclosed for the fan and the vanes that are each attached on the upper portion of the rotator (rotor) of the electric motor disclosed therein, and optimum configurations for the fan and the vanes for improving the oil separation condition have not yet been specified. 
     Specifically, in the high-pressure shell type scroll compressor disclosed in Patent Literature 1, unless the fan and the partition walls to be attached on the upper portion of the rotator of the electric motor are appropriately designed and arranged, the fan and the partition walls cannot prevent the refrigerant, which flows from the compression mechanism into the space above the electric motor (refrigerant mixed with fine oil particles), from flowing from the stator side of the electric motor directly into the rotator side of the electric motor. Thus, there is a problem in that the oil separation effect cannot be fully exerted. 
     The present invention has been made to solve the problem as described above, and it is an object thereof to provide a hermetic compressor capable of reducing an amount of oil flowing to an outside of a hermetic container than that in the related art by using rotation of a rotator of an electric motor arranged in the hermetic container, and to provide a vapor compression-type refrigeration cycle device including the hermetic compressor. 
     Solution to Problem 
     According to one embodiment of the present invention, there is provided a hermetic compressor, including: a hermetic container having a bottom portion for storing lubricating oil; an electric motor arranged in the hermetic container, the electric motor including: a stator and a rotator through which rotator vents are formed in a vertical direction; a drive shaft attached to the rotator; a compression mechanism arranged in the hermetic container, for compressing refrigerant by using rotation of the drive shaft; a rotary pressure increasing mechanism arranged on an upper portion of the rotator, for increasing a pressure of refrigerant gas by allowing the refrigerant gas to flow through the rotary pressure increasing mechanism while rotating about the drive shaft; a cylindrical lateral wall for partitioning a space above the electric motor into an outer space on the stator side in such a manner that the cylindrical lateral wall surrounds the rotary pressure increasing mechanism; and a discharge pipe communicated to the inner space, for allowing the refrigerant to flow out from the inner space into an external circuit that is external to the hermetic container, in which the refrigerant gas that is compressed by the compression mechanism and discharged into the hermetic container is moved from a space below the electric motor up to an upper end of the rotator through the rotator vents, flows into the rotary pressure increasing mechanism to be increased in pressure, flows into the inner space to increase a pressure in the inner space, and is discharged to an outside through the discharge pipe while suppressing inflow of the refrigerant gas from the outer space to the inner space. 
     Further, according to one embodiment of the present invention, there is provided a vapor compression-type refrigeration cycle device, including: the hermetic compressor of the one embodiment of the present invention; a radiator for transferring heat of refrigerant that is compressed by the hermetic compressor; an expansion mechanism for expanding the refrigerant that flows out from the radiator; and an evaporator for causing the refrigerant that flows out from the expansion mechanism to receive heat. 
     Advantageous Effects of Invention 
     The one embodiment of the present invention can prevent a decrease in amount of lubricating oil stored in the hermetic container and can obtain an effect of suppressing reliability degradation to be caused by insufficient lubrication, and an effect of achieving high energy-saving performance. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a vertical sectional view of a structure of a hermetic compressor according to Embodiment 1 of the present invention. 
         FIG. 2  is a horizontal sectional view of the structure of the hermetic compressor according to Embodiment 1 of the present invention (sectional view taken along the line A-A in  FIG. 1 ). 
         FIG. 3  is a vertical sectional view of a structure of a hermetic compressor according to Embodiment 2 of the present invention. 
         FIG. 4  is a horizontal sectional view of the structure of the hermetic compressor according to Embodiment 2 of the present invention (sectional view taken along the line A-A in  FIG. 3 ). 
         FIG. 5  is a vertical sectional view of a structure of a hermetic compressor according to Embodiment 3 of the present invention. 
         FIG. 6  is a horizontal sectional view of the structure of the hermetic compressor according to Embodiment 3 of the present invention (sectional view taken along the line A-A in  FIG. 5 ). 
         FIG. 7  is a vertical sectional view of a structure of a hermetic compressor according to Embodiment 4 of the present invention. 
         FIG. 8  is a horizontal sectional view of the structure of the hermetic compressor according to Embodiment 4 of the present invention (sectional view taken along the line A-A in  FIG. 7 ). 
         FIG. 9  is a configuration diagram of a vapor compression-type refrigeration cycle device according to Embodiment 5 of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 1 
       FIG. 1  is a vertical sectional view of a structure of a hermetic compressor according to Embodiment 1 of the present invention.  FIG. 2  is a horizontal sectional view of the structure of the hermetic compressor according to Embodiment 1 of the present invention (sectional view taken along the line A-A in  FIG. 1 ). Note that, the solid arrow shown in  FIG. 2  indicates a rotation direction of the rotary pressure increasing mechanism. 
     First, with reference to  FIGS. 1 and 2 , a fundamental structure and operation of a hermetic compressor  100  according to Embodiment 1 is described. 
     &lt;Fundamental Structure and Operation of Hermetic Compressor  100 &gt; 
     The hermetic compressor  100  according to Embodiment 1 is a high-pressure shell hermetic scroll compressor, which includes a hermetic container  1  having a bottom portion in which a lower oil reservoir  2  for storing lubricating oil is formed, and an electric motor  8 , a drive shaft  3 , a compression mechanism  60 , and a rotary pressure increasing mechanism  49  that are housed in the hermetic container  1 . 
     The electric motor  8  includes a substantially cylindrical stator  7  having an inner peripheral portion through which a through-hole is formed in a vertical direction, and a substantially cylindrical rotator  6  arranged on an inner peripheral side of the stator  7  across a predetermined air gap  27   a . The electric motor  8  according to Embodiment 1 is, for example, a DC brushless motor. The stator  7  is formed of laminated steel plates, and includes a core  7   c  that is formed into a wound coil block by winding a coil therearound at a high density. Further, at an upper end of the stator  7 , coil parts projecting from the wound coil block toward an upper side of the stator  7 , that is, a plurality of electric motor upper coil-interconnecting portion  7   a  are formed. At a lower end of the stator  7 , coil parts projecting from the wound coil block toward a lower side of the stator  7 , that is, a plurality of electric motor lower coil-interconnecting portions  7   b  are formed. This stator  7  is attached to an inner peripheral surface of the hermetic container  1  by press fitting, welding, and the like. Note that, an outer peripheral portion of the core  7   c  of the stator  7  is partially cut out so that stator outer peripheral passages  25  are formed between the core  7   c  and the hermetic container  1  under a state in which the stator  7  is attached to the inner peripheral surface of the hermetic container  1 . 
     The rotator  6  is formed by laminating steel plates and sandwiching uppermost and lowermost ones of the laminated steel plates respectively with a rotator upper end fixing substrate  33  and a rotator lower end fixing substrate  34 . Further, magnets are arranged in the rotator  6 . Still further, respectively on an upper surface of the rotator upper end fixing substrate  33  and a lower surface of the rotator lower end fixing substrate  34 , an upper balance weight  31  and a lower balance weight  32 , which have a predetermined thickness and are arranged in reverse phases, are arranged along outer rims of the rotator  6 . Yet further, four rotator vents  26  are formed in the vertical direction through the rotator  6  according to Embodiment 1. Note that, the number of the rotator vents  26  is not particularly limited as long as at least one rotator vent  26  is formed. 
     A lower end portion of the drive shaft  3  is attached to the rotator  6  of the electric motor  8 , and an upper end portion thereof is attached to the compression mechanism  60  described below. In other words, the drive shaft  3  is configured to transmit a driving force of the electric motor  8  to the compression mechanism  60 . An upper side of the drive shaft  3  is held in a freely rotatable manner by a main bearing unit  55  of an upper bearing member  11  arranged above the electric motor  8 , and a lower side thereof is held in a freely rotatable manner by a sub bearing unit  54  of a lower bearing member  12  arranged below the electric motor  8 . 
     The compression mechanism  60  is arranged above the electric motor  8 , and includes a fixed scroll  51  and an orbiting scroll  52 . Plate-like scroll teeth are formed on a lower surface of the fixed scroll  51 , which is attached to a compression mechanism casing  50  that is fixed to the inner peripheral surface of the hermetic container  1 . Plate-like scroll teeth to mesh with the plate-like scroll teeth of the fixed scroll  51  are formed on an upper surface of the orbiting scroll  52 , which is provided in a freely slidable manner at the upper end portion of the drive shaft  3 . When the plate-like scroll teeth of the fixed scroll  51  and the plate-like scroll teeth of the orbiting scroll  52  mesh with each other, compression chambers  4  are formed between the plate-like scroll teeth on both sides. A lower surface of the orbiting scroll  52  is supported in a freely slidable manner by an upper surface portion of the upper bearing member  11 . An outer peripheral surface of the upper bearing member  11  is supported in a freely slidable manner by an inner peripheral surface of the compression mechanism casing  50 . With this configuration, the upper bearing member  11  can be retracted downward in response to application of pressure of a predetermined value or more in the compression chamber  4 , and thus an abnormal pressure increase in the compression chamber  4  can be avoided. 
     Note that, a refrigerant passage  57  is formed between an outer peripheral portion of the compression mechanism casing  50  and the hermetic container  1 . Further, a discharge cover  56  for partitioning an electric motor superjacent space  9  (more specifically, upper part of a cylindrical lateral wall  37  described below) into an electric motor stator superjacent space  9   a  (outer space) and an electric motor rotator superjacent space  9   b  (inner space) is arranged under the compression mechanism casing  50 . 
     The rotary pressure increasing mechanism  49  is arranged on an upper portion of the rotator  6 . The rotary pressure increasing mechanism  49  according to Embodiment 1 is a centrifugal impeller  40 , which includes a plurality of vanes  41  arranged in a manner of extending from an inner peripheral side to an outer peripheral side about the drive shaft  3 . Further, the centrifugal impeller  40  according to Embodiment 1 also includes a vane superjacent disk  43  (upper surface plate) for blocking inflow of refrigerant gas from above the vanes  41  into the centrifugal impeller  40 , and a vane subjacent disk  44  (lower surface plate) for blocking inflow of refrigerant gas from below the vanes  41  into the centrifugal impeller  40 . Further, to prevent inflow of refrigerant gas through passages other than the rotator vents  26  into an inlet on an inner peripheral side of the centrifugal impeller  40 , an inner peripheral flow guide  42  (partition plate) is extended downward from a rim of an opening portion of the vane subjacent disk  44 , which is formed at a position on an inner peripheral side of the vanes  41 , in a manner that an outer peripheral portion of the rotator vents  26  is surrounded. The centrifugal impeller  40  is rotated about the drive shaft  3  through, for example, connection between the drive shaft  3  and the vane superjacent disk  43 , connection between the cylindrical lateral wall  37  described below and the vane subjacent disk  44 , or connection between the rotator  6  and the inner peripheral flow guide  42 . With this configuration, the refrigerant that flows in through the inlet on the inner peripheral side is increased in pressure and is caused to flow out through an outlet on the outer peripheral side. 
     Further, in the hermetic compressor  100  according to Embodiment 1, the cylindrical lateral wall  37  is arranged to surround the centrifugal impeller  40  (more specifically, refrigerant outlet on the outer peripheral side), in other words, to partition the electric motor superjacent space  9  into the electric motor stator superjacent space  9   a  (outer space) and the electric motor rotator superjacent space  9   b  (inner space). Further, in the cylindrical lateral wall  37 , an oil drain hole is formed on a rotation direction leading end portion  31   a  side of the upper balance weight  31 . This cylindrical lateral wall  37  is attached to an upper surface portion of a disk portion  38   a  of a balancer fixing bottom plate  38  for fixing the upper balance weight  31  to the rotator upper end fixing substrate  33 . Further, in Embodiment 1, a stator inner peripheral passage closing portion  38   b  (closing member) is arranged to project from an outer peripheral portion of the disk portion  38   a  of the balancer fixing bottom plate  38 . This stator inner peripheral passage closing portion  38   b  is arranged to close an upper part of a stator inner peripheral passage  27  formed between the rotator  6  and the stator  7  (specifically, air gap  27   a  between the rotator  6  and the stator  7 , and core inner peripheral portion cut-out passage  27   b  formed by cutting out the inner peripheral side of the stator  7 ). 
     In the hermetic compressor  100  configured as described above, the orbiting scroll  52  of the compression mechanism  60  performs eccentric orbital operation along with rotation of the drive shaft  3 , causing sucked low-pressure refrigerant to enter the compression chamber  4  through a compressor suction pipe  21 . Then, the sucked pressure refrigerant is increased in pressure through a compression step of gradually decreasing a volume of the compression chamber  4 , and is discharged into a discharge space  10  (( 1 ) in  FIG. 1 ) in the hermetic container  1  through a discharge port  18  of the fixed scroll  51 . 
     Further, along with the rotation of the drive shaft  3 , the lubricating oil stored in the lower oil reservoir  2  is sucked upward from a lower end of the drive shaft  3 , and flows into a hollow hole  3   a . Part of the lubricating oil is supplied, for example, to the sub bearing unit  54  and the main bearing unit  55  through oil supply holes (not shown). Further, part of the lubricating oil flows out from an upper end of the drive shaft  3 , and then is supplied into the compression chamber  4  through, for example, a gap between the upper bearing member  11  and the orbiting scroll  52  and an oil supply hole  3   b , increasing effects of lubrication of the compression mechanism  60  and sealing of the compressed gas. The lubricating oil that is supplied in the compression chamber  4  is discharged into the discharge space  10  (( 1 ) in  FIG. 1 ) in the hermetic container  1  through the discharge port  18  of the fixed scroll  51  together with the refrigerant compressed to have a high pressure in the compression chamber  4 . 
     &lt;Flow of Refrigerant in Hermetic Container&gt; 
     The refrigerant that is discharged through the discharge port  18  flows downward through the refrigerant passage  57  formed of a gap between an outer peripheral side of the compression mechanism casing  50  and the hermetic container  1 , and reaches the electric motor stator superjacent space  9   a  (( 2 ) in  FIG. 1 ). Further, this refrigerant flows downward into an electric motor stator subjacent space (( 3 ) in  FIG. 1 ) in an electric motor subjacent space  5  through the stator outer peripheral passages  25  formed between the core  7   c  of the stator  7  and the hermetic container  1 , and reaches the lower bearing member  12  including the sub bearing unit  54 . During this process, the refrigerant and the lubricating oil mixed in an atomized form with the refrigerant are separated from each other, and the separated lubricating oil is refluxed to the lower oil reservoir  2  through an oil return hole  12   a  formed through the lower bearing member  12 . 
     Meanwhile, the refrigerant that flows in the electric motor stator subjacent space in the electric motor subjacent space  5  flows up from an electric motor rotator subjacent space (( 4 ) in  FIG. 1 ) in the electric motor subjacent space  5  through the rotator vents  26  into a vane inner passage  46  of the centrifugal impeller  40  attached on an upper portion of the rotator  6  (passage on an inner peripheral side of the inner peripheral flow guide  42 , that is, space represented by ( 5 ) in  FIG. 1 ). Then, the refrigerant that flows in the vane inner passage  46  is sucked into inter-vane passages  47  formed between the vanes  41  of the centrifugal impeller  40 , flows to the outer peripheral side while being increased in pressure in accordance with a rotational speed of the centrifugal impeller  40 , and, on an outer peripheral side of the vanes  41 , flows up through a vane outer passage  48  formed in a region on an inner peripheral side of the cylindrical lateral wall  37 . Then, this refrigerant is once released into the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) that is formed above the circular vane superjacent disk  43  covering upper surfaces of the vanes  41  of the centrifugal impeller  40  and on the inner peripheral side of the cylindrical lateral wall  37 . With this, static pressure is increased. After that, the refrigerant that flows in the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) flows into the discharge cover  56  through an opening portion  56   a  of the discharge cover  56 , and then is discharged into an external circuit on an outside of the hermetic container  1  through a compressor discharge pipe  22  that communicates to an inner space of the discharge cover  56 . 
     &lt;Flow in Short Circuit Passage  23  and Short-Circuit Prevention&gt; 
     To prevent electrical short-circuiting between the electric motor upper coil-interconnecting portions  7   a  and the discharge cover  56 , a gap between the electric motor upper coil-interconnecting portions  7   a  and the discharge cover  56 , that is, a short circuit passage  23  needs to be formed. Thus, during the process from the discharge space  10  (( 1 ) in  FIG. 1 ) to the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ), the refrigerant may flow from the electric motor stator superjacent space  9   a  (( 2 ) in  FIG. 1 ) directly into the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) without flowing through the electric motor stator subjacent space (( 3 ) in  FIG. 1 ). As a result, a large number of droplets of unseparated oil may flow out from the hermetic container  1  to the external circuit, which may cause degradation in performance and reliability of the hermetic compressor  100 , and degradation in performance of the vapor compression-type refrigeration cycle device (in particular, of the heat exchanger). 
     In view of the circumstances, to reduce an amount of the flow of the refrigerant that short-circuits to be directly discharged through the short circuit passage  23 , the following measures need to be taken. 
     (1) Set a passage resistance of the short circuit passage  23  to the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) to be sufficiently high. 
     (2) Increase a pressure in the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) to be close to or higher than a pressure in the electric motor stator superjacent space  9   a.    
     Thus, in Embodiment 1, the cylindrical lateral wall  37  is arranged upright to the balancer fixing bottom plate  38  so that a passage area of the short circuit passage  23  is reduced, and thus the passage resistance is increased. Further, a lower end portion of the discharge cover  56  is bent so that a passage shape of the short circuit passage  23  is made complicated, and thus the passage resistance of the short circuit passage  23  is further increased. 
     In addition, in Embodiment 1, the cylindrical lateral wall  37  is interposed to separate the centrifugal impeller  40  arranged on the rotator  6  and the electric motor upper coil-interconnecting portions  7   a  from each other. With this, the refrigerant gas that is increased in pressure by the centrifugal impeller  40  can be suppressed from reversely flowing into the electric motor stator superjacent space  9   a  (( 2 ) in  FIG. 1 ) through radial passages  28  in the electric motor upper coil-interconnecting portions  7   a . As a result, the pressure in the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) can be increased. 
     Note that, other than the rotator vents  26 , the stator inner peripheral passage  27  (air gap  27   a  and core inner peripheral portion cut-out passage  27   b ) is formed as an upward refrigerant passage from the electric motor subjacent space  5  (( 3 ) or ( 4 ) in  FIG. 1 ) to the electric motor superjacent space  9  (( 2 ) or ( 5 ) in  FIG. 1 ), and the pressure increasing effect by the centrifugal impeller  40  cannot be exerted to the refrigerant gas that flows through the stator inner peripheral passage  27 . Therefore, a greater pressure increasing effect can be obtained by the centrifugal impeller  40  when the stator inner peripheral passage  27  is closed as much as possible. Thus, in Embodiment 1, to slightly increase an outer diameter of the balancer fixing bottom plate  38  (for example, approximately 1 mm), the stator inner peripheral passage closing portion  38   b  is arranged to the outer peripheral portion of the disk portion  38   a  so that the upper part of the stator inner peripheral passage  27  is closed. With this, an amount of the refrigerant gas that flows through the stator inner peripheral passage  27  can be suppressed, and thus the pressure in the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) can be further increased. 
     &lt;Design of Centrifugal Impeller&gt; 
     To increase the pressure in the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) with the centrifugal impeller  40  such that approximately 100% of the refrigerant flows from the electric motor stator superjacent space  9   a  (( 2 ) in  FIG. 1 ) to the electric motor stator subjacent space (( 3 ) in  FIG. 1 ), the shape of the vanes and the passages of the centrifugal impeller  40  need to be designed such that a pressure (P 6 ) in the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) is higher than a pressure (P 2 ) in the electric motor stator superjacent space  9   a  (( 2 ) in  FIG. 1 ). Further, to increase a pressure in the centrifugal impeller  40 , input to the compressor (electric power consumption thereof) is increased. Thus, it is also important to design a highly-efficient centrifugal impeller  40 . 
     According to Non Patent Literature 2 (p. 132), of centrifugal fans, a turbofan (having vanes that are formed rearward with respect to a rotation direction) is advantageous in terms of efficiency. Thus, the shape of the vanes  41  of the centrifugal impeller  40  is determined to be rearward with respect to the rotation direction, and eight vanes  41  formed into this shape are arranged in axial symmetry with respect to the drive shaft  3 . Further, an inlet angle of each of the vanes  41  is determined such that the vanes  41  each form an angle within a range of ±5 degrees with respect to a circle formed by connecting end positions on the inner peripheral side of the vanes  41 . This is because, according to Non Patent Literature 1 (p. 216), a collision loss occurs when an entry angle ib that is equal to a difference between a relative inflow angle β 1  and a vane inlet angle β 1   b  at an inlet of the impeller ranges from 2 degrees to 5 degrees or more, causing losses in the compressor. Note that, to increase a percentage by which the refrigerant that flows through the rotator vents  26  flows into the inner peripheral side of the centrifugal impeller  40 , and then flows out to the outer peripheral side thereof (passage rate), the following configurations are devised.
         The rotator vents  26  are arranged on an inner side with respect to the inner peripheral flow guide  42  in plan view.   The vane superjacent disk  43  and the vane subjacent disk  44  for covering the upper and lower sides of the vanes  41  are configured to cover all over the inner peripheral side to the outer peripheral side of the plurality of vanes  41 .       

     With this, the pressure increasing effect by the centrifugal impeller  40  can be further increased, and the pressure in the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) can be further increased. 
     &lt;Effects&gt; 
     In the hermetic compressor  100  configured as in Embodiment 1, the pressure in the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) can be increased by using rotation of the rotator  6  in the hermetic container  1 . Specifically, when the hermetic compressor  100  that is configured to output three horsepower and operated at a constant speed (50 rps), is operated by using a refrigerant R22 under the condition of Ashrae standard, an effect of increasing the pressure in the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) in units of several kPa can be obtained. As a result, the refrigerant is less liable to flow from the electric motor stator superjacent space  9   a  (( 2 ) in  FIG. 1 ) directly into the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 1 ) through the short circuit passage  23 , and the large number of droplets of the unseparated oil are less liable to flow out from the hermetic container  1  to the external circuit. Further, to effectively use the sealed lubricating oil, an effect of suppressing the degradation in performance of the hermetic compressor  100 , and an effect of suppressing the degradation in reliability thereof due to insufficient lubrication that may be caused by a decrease in amount of the oil stored in the hermetic container  1  can be obtained. 
     Embodiment 2 
       FIG. 3  is a vertical sectional view of a structure of a hermetic compressor according to Embodiment 2 of the present invention.  FIG. 4  is a horizontal sectional view of the structure of the hermetic compressor according to Embodiment 2 of the present invention (sectional view taken along the line A-A in  FIG. 3 ). Note that, the solid arrow shown in  FIG. 4  indicates a rotation direction of the rotary pressure increasing mechanism. 
     Now, with reference to  FIGS. 3 and 4 , the hermetic compressor  100  according to Embodiment 2 is described. Note that, the fundamental structure and the operation of the hermetic compressor  100  according to Embodiment 2 are the same as those in Embodiment 1, and hence description thereof is omitted. 
     (1) Embodiment 2 is different from Embodiment 1 in that only four of the eight vanes  41  of the centrifugal impeller  40  in Embodiment 1 that are positioned on one side on which the upper balance weight  31  is absent are left, and that a height of each of the four vanes  41  is designed to be equal to a height of the upper balance weight  31 . In Embodiment 1, to allow the refrigerant flowing through the rotator vents  26  to flow out from the centrifugal impeller  40  through the vane inner passage  46 , the inner peripheral flow guide  42  and the vane subjacent disk  44  are needed. In contrast, in Embodiment 2, there is an advantage in that the inner peripheral flow guide  42  and the vane subjacent disk  44  can be omitted, and hence the centrifugal impeller  40  is easily processed. 
     Note that, in a case where the centrifugal impeller  40  is configured as in Embodiment 2, fan efficiency is lower than that of the centrifugal impeller  40  according to Embodiment 1, in which the vanes  41  are arranged in axial symmetry. Further, in the case where the centrifugal impeller  40  is configured as in Embodiment 2, pressure pulsation by the centrifugal impeller  40  is increased in comparison with that by the centrifugal impeller  40  according to Embodiment 1, in which the vanes  41  are arranged in axial symmetry. As a result, vibration and noise may occur. Thus, in a case where the fan efficiency and prevention of the vibration and noise are regarded as important, it is preferred that the centrifugal impeller  40  be configured as in Embodiment 1. 
     (2) In Embodiment 1, the cylindrical lateral wall  37  for preventing short-circuit flow of the refrigerant through the short circuit passage  23 , and the balancer fixing bottom plate  38  for fixing the cylindrical lateral wall  37  are formed as separate members. Meanwhile, in Embodiment 2, the cylindrical lateral wall  37  and the balancer fixing bottom plate  38  according to Embodiment 1 are provided as an oil separating cup  36  obtained by a process of integrating a cylindrical lateral wall  36   a  and a bottom plate  36   b  with each other. Note that, similarly to Embodiment 1, an oil drain hole  36   c  is formed in the oil separating cup  36  on the rotation direction leading end portion  31   a  side of the upper balance weight  31 . When the oil separating cup  36  obtained by the process of integrating the cylindrical lateral wall  36   a  and the bottom plate  36   b  with each other is provided instead of the cylindrical lateral wall  37  and the balancer fixing bottom plate  38  according to Embodiment 1, there is an advantage in that a process of assembling the hermetic compressor  100  can be facilitated. 
     In this way, according to the hermetic compressor  100  configured as in Embodiment 2, the decrease in amount of the lubricating oil stored in the hermetic container  1  can be prevented. In addition, an effect of suppressing reliability degradation caused by insufficient lubrication and an effect of suppressing energy-saving performance degradation, which are comparably less than those in Embodiment 1 but are equivalent thereto, can be obtained. Meanwhile, according to the hermetic compressor  100  configured as in Embodiment 2, there is an advantage in that a manufacturing cost for the centrifugal impeller  40  is lower than that in Embodiment 1. 
     (3) Note that, other differences between the hermetic compressor  100  according to Embodiment 2 and the hermetic compressor  100  described in Embodiment 1 are as follows.
         In the hermetic compressor  100  according to Embodiment 2, the lower end portion of the discharge cover  56  is not subjected to a bending process, and hence the short circuit passage  23  has a simple shape. Thus, in the hermetic compressor  100  according to Embodiment 2, the passage resistance in the short circuit passage  23  is determined based on a size of a smallest gap that is formed between the discharge cover  56  and the cylindrical lateral wall  36   a.      Further, the hermetic compressor  100  according to Embodiment 2 does not include the closing member for closing the stator inner peripheral passage  27  (counterpart of the stator inner peripheral passage closing portion  38   b  in Embodiment 1).       

     Embodiment 3 
       FIG. 5  is a vertical sectional view of a structure of a hermetic compressor according to Embodiment 3 of the present invention.  FIG. 6  is a horizontal sectional view of the structure of the hermetic compressor according to Embodiment 3 of the present invention (sectional view taken along the line A-A in  FIG. 5 ). Note that, the solid arrow shown in  FIG. 6  indicates a rotation direction of the rotary pressure increasing mechanism. 
     Now, with reference to  FIGS. 5 and 6 , the hermetic compressor  100  according to Embodiment 3 is described. Note that, the fundamental structure and the operation of the hermetic compressor  100  according to Embodiment 3 are the same as those in Embodiment 1, and hence description thereof is omitted. 
     (1) Similarly to Embodiment 2, in the centrifugal impeller  40  according to Embodiment 3, only four of the eight vanes  41  of the centrifugal impeller  40  in Embodiment 1 that are positioned on the one side on which the upper balance weight  31  is absent are left, and the height of each of the four vanes  41  is designed to be equal to the height of the upper balance weight  31 . However, the centrifugal impeller  40  according to Embodiment 3 is different from that according to Embodiment 2 in that the vanes  41  are arranged in a radial direction (direction orthogonal to the rotation direction of the drive shaft  3 ). With this, although fan efficiency is lower than that of the turbofan, there is an advantage in that the centrifugal impeller  40  can be easily manufactured. 
     (2) In Embodiments 1 and 2, the cylindrical lateral wall (cylindrical lateral wall  37  or cylindrical lateral wall  36   a ) for preventing the short-circuit flow of the refrigerant through the short circuit passage  23  is arranged on the upper portion of the rotator  6  so that the cylindrical lateral wall is rotated together with the rotator  6 . In contrast, in Embodiment 3, a closing cover  29  (more specifically, cylindrical portion  29   a ) as a counterpart of the cylindrical lateral wall is arranged on an inner side of the electric motor upper coil-interconnecting portions  7   a  of the stator  7  so that the radial passages  28  are closed. Further, in the closing cover  29 , on an inner peripheral side of the cylindrical portion  29   a , a projecting portion  29   b  for closing the upper part of the stator inner peripheral passage  27  is formed. This projecting portion  29   b  is a counterpart of the stator inner peripheral passage closing portion  38   b  in Embodiment 1, and is designed such that a smallest gap  29   c  between the projecting portion  29   b  and the disk portion  38   a  of the balancer fixing bottom plate  38  is narrowed (for example, approximately 1 mm to 2 mm) within a range in which electrical short-circuiting does not occur. Note that, in a case where this design is employed, a pressure increasing effect by rotation of the cylindrical lateral wall about the drive shaft cannot be obtained. 
     In this way, according to the hermetic compressor  100  configured as in Embodiment 3, the decrease in amount of the lubricating oil stored in the hermetic container  1  can be prevented. In addition, the effect of suppressing reliability degradation caused by insufficient lubrication and the effect of suppressing energy-saving performance degradation, which are comparably less than those in Embodiment 1 but are equivalent thereto, can be obtained. 
     Embodiment 4 
       FIG. 7  is a vertical sectional view of a structure of a hermetic compressor according to Embodiment 4 of the present invention.  FIG. 8  is a horizontal sectional view of the structure of the hermetic compressor according to Embodiment 4 of the present invention (sectional view taken along the line A-A in  FIG. 7 ). Note that, the solid arrow shown in  FIG. 8  indicates a rotation direction of the rotary pressure increasing mechanism. 
     Now, with reference to  FIGS. 7 and 8 , the hermetic compressor  100  according to Embodiment 4 is described. Note that, the fundamental structure and the operation of the hermetic compressor  100  according to Embodiment 4 are the same as those in Embodiment 1, and hence description thereof is omitted. 
     (1) The configuration of the hermetic compressor  100  according to Embodiment 4 is the same as the configuration of the hermetic compressor  100  described in Embodiment 2 except the configuration of the rotary pressure increasing mechanism  49 . Specifically, the rotary pressure increasing mechanism  49  according to Embodiment 4 is obtained by removing all the vanes  41  from the centrifugal impeller  40  described in Embodiment 1. In other words, the rotary pressure increasing mechanism  49  according to Embodiment 4 includes an oil separating rotary disk  35  as a counterpart of the vane superjacent disk  43  in Embodiment 1, and a balancer cover  30  including a rotary disk  30   b  and an inner peripheral flow guide  30   c  as respective counterparts of the vane subjacent disk  44  and the inner peripheral flow guide  42  in Embodiment 1. In the rotary pressure increasing mechanism  49  configured in this way, the refrigerant that flows out from the rotator vents  26  flows into an inner passage  30   a  formed on an inner peripheral side of the inner peripheral flow guide  30   c , flows between the rotary disk  30   b  and the oil separating rotary disk  35 , and flows out into the electric motor rotator superjacent space  9   b  (( 6 ) in  FIG. 7 ) through a cup inner passage  36   d  formed on an inner peripheral side of the oil separating cup  36 . In the rotary pressure increasing mechanism  49  according to Embodiment 4, although the great pressure increasing effect (for example, in units of several kPa) by the centrifugal impeller cannot be obtained, a pressure increasing effect (for example, 1 kPa or less) can be obtained by rotations of the rotary disk  30   b  of the balancer cover  30 , the oil separating rotary disk  35 , and the cylindrical lateral wall  36   a  of the oil separating cup  36 . 
     In this way, according to the hermetic compressor  100  configured as in Embodiment 4, the decrease in amount of the lubricating oil stored in the hermetic container  1  can be prevented. In addition, the effect of suppressing reliability degradation caused by insufficient lubrication and the effect of suppressing energy-saving performance degradation, which are comparably less than (for example, less than half of) those in Embodiment 1 but are equivalent thereto, can be obtained. Meanwhile, according to the hermetic compressor  100  configured as in Embodiment 4, there is an advantage in that a manufacturing cost for the rotary pressure increasing mechanism  49  is lower than that in Embodiment 1. 
     In Embodiments 1 to 4, the present invention is described with an example of the high-pressure shell hermetic scroll compressor. In this context, also when other rotary compression types (such as sliding-vane type and swing type) are employed, the same effects as those in Embodiments 1 to 4 can be obtained as long as the arrangement of the rotator  6  and the stator  7  of the electric motor  8 , and the flow of the refrigerant from the electric motor subjacent space  5  to the electric motor superjacent space  9  are unchanged. 
     Embodiment 5 
     In Embodiment 5, an example of the vapor compression-type refrigeration cycle device including the hermetic compressor  100  described in any one of Embodiments 1 to 4 is described. 
       FIG. 9  is a configuration diagram of a vapor compression-type refrigeration cycle device  101  according to Embodiment 5. The vapor compression-type refrigeration cycle device  101  includes the hermetic compressor  100  described in any one of Embodiments 1 to 4, a radiator  102  for transferring heat of the refrigerant compressed by the hermetic compressor  100 , an expansion mechanism  103  for expanding the refrigerant that flows out from the radiator  102 , and an evaporator  104  for causing the refrigerant that flows out from the expansion mechanism  103  to receive heat. When the hermetic compressor  100  according to any one of Embodiments 1 to 4 is used in the vapor compression-type refrigeration cycle device  101 , the vapor compression-type refrigeration cycle device  101  can be improved in energy saving efficiency, reduced in vibration and noise, and increased in reliability. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  hermetic container  2  lower oil reservoir  3  drive shaft  3   a  hollow hole  3   b  oil supply hole  4  compression chamber  5  electric motor subjacent space  6  rotator 
               7  stator  7   a  electric motor upper coil-interconnecting portion  7   b  electric motor lower coil-interconnecting portion  7   c  core  8  electric motor  9  electric motor superjacent space  9   a  electric motor stator superjacent space  9   b  electric motor rotator superjacent space  10  discharge space  11  upper bearing member  12  lower bearing member  12   a  oil return hole  18  discharge port  21  compressor suction pipe  22  compressor discharge pipe  23  short circuit passage  25  stator outer peripheral passage  26  rotator vent  27  stator inner peripheral passage  27   a  air gap  27   b  core inner peripheral portion cut-out passage  28  radial passage  29  closing cover  29   a  cylindrical portion  29   b  projecting portion for closing stator inner peripheral passage  29   c  smallest gap  30  balancer cover  30   a  inner passage  30   b  rotary disk  30   c  inner peripheral flow guide  31  upper balance weight  31   a  rotation direction leading end portion  31   b  rotation direction trailing end portion  32  lower balance weight  33  rotator upper end fixing substrate  34  rotator lower end fixing substrate  35  oil separating rotary disk (single member)  36  oil separating cup  36   a  cylindrical lateral wall  36   b  bottom plate 
               36   c  oil drain hole  36   d  cup inner passage  37  cylindrical lateral wall (single member)  38  balancer fixing bottom plate  38   a  disk portion  38   b  stator inner peripheral passage closing portion  40  centrifugal impeller  41  vane  42  inner peripheral flow guide  43  vane superjacent disk  44  vane subjacent disk  46  vane inner passage  47  inter-vane passage  48  vane outer passage  49  rotary pressure increasing mechanism  50  compression mechanism casing  51  fixed scroll  52  orbiting scroll  54  sub bearing unit  55  main bearing unit  56  discharge cover  56   a  opening portion  57  refrigerant passage  60  compression mechanism  100  hermetic compressor  101  vapor compression-type refrigeration cycle device  102  radiator  103  expansion mechanism  104  evaporator