Abstract:
Previous compressors have employed compressors to compress and circulate refrigerant through a circuit, and have been unable to combine the differing advantages of rotary compressors, scroll compressors and screw compressors. The present invention combines these advantages, as well as inhibiting refrigerant leakage and improving overall performance, by particularly fixing the position of the compression member of the compression element relative to the driving element. The driving element is stored in a sealed container of the compressor. The compression element includes a cylinder having suction and discharge ports and a compression member which compresses a fluid (refrigerant) sucked from the suction port to discharge the fluid via the discharge port; and a vane partitioning the compression space in the cylinder into a low pressure chamber and a high pressure chamber.

Description:
This applications is a Divisional of prior application Ser. No. 11/219,915 filed on Sep. 7, 2005 now U.S. Pat. No. 7,381,040, the contents being incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a compressor which compresses fluids such as refrigerants or air and discharges the compressed fluids. 
   For example, a refrigerator has heretofore employed a system in which a compressor is used to compress a refrigerant and the compressed refrigerant is circulated through a circuit. As the systems of the compressor in this case, there are a rotary compressor called a rotary type compressor (e.g., see Japanese Patent Application Laid-Open No. 5-99172 (Patent Document 1)), a scroll compressor, and a screw compressor. 
   The rotary compressor has advantages that a structure is relatively simple and production costs are low, but there is a problem of increases in vibration and torque fluctuation. In the case of the scroll compressor and the screw compressor, there is a problem of high costs caused by bad workability while torque fluctuation is small. 
   Thus, there has been developed a system which disposes a swash plate as a rotary compression member in a cylinder and partitions compression spaces constituted below and above the swash plate by a vane to compress fluids (e.g., PCT No. 2003-532008 (Patent Document 2)). According to the compressor of such system, there is an advantage of constituting a compressor which is relatively simple in structure and small in vibration. 
   However, in the case of the structure of the Patent Document 2, since a high pressure chamber and a low pressure chamber are adjacent to each other below and above the compression member (swash plate) in the entire region of the cylinder, a difference between high and low pressures is enlarged, and refrigerant leakage causes a problem of efficiency deterioration 
   Especially in a case where one surface of the compression member is disposed on a driving element side, the refrigerant in the compression space easily leaks between a rotary shaft and a bearing of the rotary shaft, and a performance of the compressor has been degraded. 
   Moreover, even in the compressor having the structure described in Patent Document 2 described above, an oil reservoir is formed in a lower part of a sealed container in the same manner as in the conventional compressor of Patent Document 1 described above. Since oil is supplied from the oil reservoir to the compression element by an oil pump, there has occurred a problem that it becomes difficult to supply the oil by the oil pump, and the supplied oil is insufficient in a case where the compression element is disposed in a position distant from the oil reservoir, such as a position above the driving element. 
   SUMMARY OF THE INVENTION 
   The present invention has been made to solve the aforementioned conventional technical problems, and an object thereof is to inhibit refrigerant leakage and improve a performance of a compressor. 
   Another object of the present invention is to supply oil smoothly to a sliding portion or the like of a compression element in a compressor in which the compression element is disposed above a driving element. 
   A first aspect of the present invention is directed to a compressor comprising a driving element stored in a sealed container, and a compression element driven by a rotary shaft of the driving element, the compression element comprising a cylinder in which a compression space is constituted; a suction port and a discharge port which communicate with the compression space in the cylinder; a compression member whose one surface crossing an axial direction of the rotary shaft is inclined continuously between a top dead center and a bottom dead center and which is rotatably disposed in the cylinder and which compresses a fluid sucked from the suction port to discharge the fluid from the discharge port; and a vane which is disposed between the suction port and the discharge port to abut on one surface of the compression member and which partitions the compression space in the cylinder into a low pressure chamber and a high pressure chamber, wherein one surface of the compression member is disposed on a side opposite to the driving element. 
   A second aspect of the present invention is directed to the above compressor, wherein the compression element is disposed above the driving element. 
   A third aspect of the present invention is directed to the above compressor, further comprising an oil pump for supplying oil to the compression element from an oil reservoir in a bottom part of the sealed container, wherein the fluid is discharged from the discharge port into the sealed container, and a back pressure of the vane is set to a value which is higher than that of a pressure of the fluid sucked into the suction port and which is lower than that of a pressure in the sealed container. 
   A fourth aspect of the present invention is directed to the above compressor, wherein the compression element is disposed below the driving element. 
   A fifth aspect of the present invention is directed to the above the compressor, further comprising a pipe which extends from the discharge port onto an oil surface of the oil reservoir in the bottom part of the sealed container. 
   A sixth aspect of the present invention is directed to a compressor comprising a driving element stored in a sealed container, and a compression element driven by a rotary shaft of the driving element, the compression element comprising a cylinder in which a compression space is constituted; a suction port and a discharge port which communicate with the compression space in the cylinder; a compression member whose one surface crossing an axial direction of the rotary shaft is inclined continuously between a top dead center and a bottom dead center and which is rotatably disposed in the cylinder and which compresses a fluid sucked from the suction port to discharge the fluid from the discharge port; and a vane which is disposed between the suction port and the discharge port to abut on one surface of the compression member and which partitions the compression space in the cylinder into a low pressure chamber and a high pressure chamber, wherein the compression element is disposed above the driving element, and oil is supplied to the compression element from an oil reservoir in a bottom part of the sealed container by an oil pump. 
   A seventh aspect of the present invention is directed to the above compressor, wherein bearings of the rotary shaft are disposed in an upper part and/or a lower part of the compression element, and a lower part of the driving element. 
   An eighth aspect of the present invention is directed to the above compressor, wherein the fluid is discharged from the discharge port into the sealed container, and a pressure on a side of the other surface of the compression member is set to a value which is higher than that of a pressure of the fluid sucked into the suction port and which is lower than that of a pressure in the sealed container. 
   A ninth aspect of the present invention is directed to the above compressor, wherein one surface of the compression member is disposed on a side opposite to the driving element, and a back pressure of the vane is set to a value which is higher than that of the pressure on the other surface side of the compression member and which is lower than that of the pressure in the sealed container. 
   According to the first aspect of the present invention, since one surface of the compression member is disposed on a side opposite to the driving element, a gas does not easily leak from a bearing, and the performance can be improved. 
   Especially even in a case where the compression element is disposed above the driving element as in the second aspect of the present invention, the gas does not easily leak, and it is therefore possible to avoid a disadvantage that a peripheral surface of the rotary shaft has a high pressure. It is possible to supply the oil to the compression element from the oil reservoir in the lower part of the sealed container by the oil pump as in the third aspect of the present invention. 
   Furthermore, when the back pressure of the vane is set to a value which is higher than that of the pressure of the fluid sucked into the suction port and which is lower than that of the pressure in the sealed container as in the third aspect of the present invention, the oil can be smoothly supplied to the sliding portion by the oil pump using a pressure difference. 
   In addition, in a case where the compression element is disposed below the driving element as in the fourth aspect of the present invention, there is disposed the pipe extending from the discharge port onto the oil surface of the oil reservoir in the lower part of the sealed container as in the fifth aspect of the present invention. Accordingly, since the fluid discharged from the discharge port is guided onto the oil surface via the pipe, pulsations of the discharged fluid can be reduced. 
   According to the sixth aspect of the present invention, the compression element is disposed above the driving element, and the oil is supplied to the compression element from the oil reservoir in the lower part of the sealed container by the oil pump. Therefore, the pressure of the compression member on the other surface side is set to a value which is higher than that of the pressure of the fluid sucked into the suction port and which is lower than that of the pressure in the sealed container as in the eighth aspect of the present invention. Consequently, the oil can be supplied even in a case where the compression element is disposed above the driving element. 
   Moreover, since the bearings of the rotary shaft are disposed in an upper part and/or a lower part of the compression element, and in a lower part of the driving element as in the seventh aspect of the present invention, the rotary shaft can be stably supported, and vibrations generated in the compressor can be effectively reduced. 
   Especially when one surface of the compression member is disposed on the side opposite to the driving element as in the ninth aspect of the present invention, the gas does not easily leak from the bearing, and sealability of the bearing can be improved. Furthermore, the back pressure of the vane is set to the value which is higher than that of the pressure of the compression member on the other surface side and which is lower than that of the pressure in the sealed container, and it is therefore possible to supply the oil utilizing the pressure difference. 
   Consequently, in the compressor in which the compression element is disposed above the driving element, the oil can be smoothly supplied, and reliability can be improved. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a vertical sectional side view of a compressor according to a first embodiment of the present invention; 
       FIG. 2  is another vertical sectional side view of the compressor of  FIG. 1 ; 
       FIG. 3  is still another vertical sectional side view of the compressor of  FIG. 1 ; 
       FIG. 4  is a perspective view showing a compression element of the compressor of  FIG. 1 ; 
       FIG. 5  is a vertical sectional side view showing the compression element of the compressor according to a second embodiment of the present invention; 
       FIG. 6  is another vertical sectional side view of the compressor of  FIG. 5 ; 
       FIG. 7  is still another vertical sectional side view of the compressor of  FIG. 5 ; 
       FIG. 8  is a vertical sectional side view showing the compression element of the compressor according to a third embodiment of the present invention; 
       FIG. 9  is another vertical sectional side view of the compressor of  FIG. 8 ; and 
       FIG. 10  is still another vertical sectional side view of the compressor of  FIG. 8 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Embodiments of the present invention will be described hereinafter in detail with reference to the accompanying drawings. A compressor C of each embodiment described below constitutes, e.g., a refrigerant circuit of a refrigerator, and plays a role of sucking, compressing and discharging the refrigerant into the circuit. 
   First Embodiment 
     FIG. 1  is a vertical sectional side view showing a compressor C according to a first embodiment of the present invention,  FIG. 2  is another vertical sectional side view of the compressor C of  FIG. 1 ,  FIG. 3  is still another vertical sectional side view of the compressor C of  FIG. 1 , and  FIG. 4  is a perspective view of a compression element  3  of the compressor C of the compressor C of  FIG. 1 , respectively. 
   Throughout the drawings, a reference numeral  1  denotes a sealed container which receives the compression element  3  on its upper side and a driving element  2  on its lower side. That is, the compression element  3  is disposed above the driving element  2 . 
   The driving element  2  is an electromotive motor which is fixed to an inner wall of the sealed container  1  and which comprises a stator  4  having a stator coil wound therearound and a rotor  6  having a rotary shaft  5  in a center inside the stator  4 . 
   The compression element  3  comprises a support member  77  fixed to the inner wall of the sealed container  1  and positioned on an upper end side of the rotary shaft  5 ; a cylinder  78  attached to an underside of the support member  77  by bolts; a compression member  89 , a vane  11 , and a discharge valve  12  arranged in the cylinder  78 ; a main support member  79  attached to the underside of the cylinder  78  via bolts and the like. A lower surface central portion of the main support member  79  concentrically projects downward, and a main bearing  13  of the rotary shaft  5  is formed therein. An upper surface of the main support member  79  closes a lower opening of the cylinder  78 . 
   The support member  77  comprises a main member  85  whose outer peripheral surface is fixed to the inner wall of the sealed container  1 ; a sub-bearing  83  extended through the center of the main member  85 ; and a projected part  84  fixed to a lower surface central portion of the sub-bearing  83  by bolts. A lower surface  84 A of this projected part  84  is formed into a smooth surface. 
   A slot  16  is formed in the projected part  84  of the support member  77 , and the vane  11  is inserted into this slot  16  to reciprocate up and down. A back pressure chamber  17  is formed in an upper part of the slot  16 , and a coil spring  18  is arranged as urging means in the slot  16  to urge an upper surface of the vane  11  downward. 
   Moreover, an upper opening of the cylinder  78  is closed by the support member  77 , so that a compression space  21  is constituted inside the cylinder  78  (between the compression member  89  and the projected part  84  of the support member  77  in the cylinder  78 ). A suction passage  24  is formed in the main member  85  and the projected part  84  of the support member  77 , and a suction pipe  26  is attached to the sealed container  1  to be connected to one end of the suction passage  24 . A suction port  27  and a discharge port  28  are formed in the cylinder  78  to communicate with the compression space  21 . The other end of the suction passage  24  communicates with the suction port  27 . Additionally, the vane  11  is positioned between the suction port  27  and the discharge port  28  ( FIG. 4 ). 
   The rotary shaft  5  is rotatably supported by the main bearing  13  formed on the main support member  79 , the sub-bearing  83  formed on the support member  77 , and a sub-bearing  86  formed on a lower end. That is, the rotary shaft  5  is inserted into centers of the main support member  79 , the cylinder  78 , and the support member  77 , and its central portion of an up-and-down direction is rotatably supported by the main bearing  13 . An upper part of the rotary shaft  5  is rotatably supported by the sub-bearing  83 , and an upper end thereof is covered with the support member  77 . Furthermore, a lower part of the rotary shaft  5  is supported by the sub-bearing  86 . This sub-bearing  86  is disposed under the driving element  2 , and substantially has a donut shape having a hole for passing the rotary shaft  5  in the central portion. An outer peripheral edge of the sub-bearing rises in an axial center direction, and the sub-bearing is fixed to the inner wall of the sealed container  1 . Several vertically communicating holes  87  are formed in this sub-bearing  86 . Recesses  88  formed in the sub-bearing  86  have a vibration absorbing function of preventing vibration transmitted from the driving element  2  or the like to the rotary shaft  5  from being transmitted to the sealed container  1  via the sub-bearing  86 . 
   As described above, the bearings of the rotary shaft  5  are disposed in the upper part (sub-bearing  83 ) of the compression element  3 , the lower part (main bearing  13 ) thereof, and in the lower part (sub-bearing  86 ) of the driving element  2 . Consequently, the rotary shaft  5  is stably supported, and the vibration generated in the compressor C can be effectively reduced. This can achieve enhancement of a vibration characteristic of the compressor C. 
   Moreover, when the compression space  21  is disposed in an upper surface  93  of the compression member  89  on a side opposite to the driving element  2 , gas leakage from the main bearing  13  is not easily generated, and sealability of the main bearing  13  can be enhanced. Furthermore, when the upper end of the rotary shaft  5  is closed by the support member  77 , the sealability of the sub-bearing  83  is improved, and it is possible to avoid a disadvantage that a peripheral surface of the rotary shaft  5  has a high pressure. 
   It has heretofore been difficult to supply oil from an oil reservoir  36  in a bottom part of the sealed container  1  to a sliding portion such as the compression member  89  of the compression element  3  in a case where the compression element  3  is disposed in the upper part of the sealed container  1 . 
   That is, since a high-pressure gas enters the peripheral surface of the rotary shaft  5  to provide the high pressure, it has not been possible to supply the oil smoothly from oil holes  44 ,  45  disposed in the upper part of the rotary shaft  5  and formed ranging from an oil passage  42  to the side surface of the compression element  3  in an axial direction of the rotary shaft  5 . 
   However, when the upper end of the rotary shaft  5  is closed by the support member  77 , the sealability of the sub-bearing  83  can be improved, and it is possible to avoid the disadvantage that the peripheral surface of the rotary shaft  5  has the high pressure. Therefore, it is possible to supply the oil to a sliding portion such as the compression member  89  disposed in the upper part of the sealed container  1  by an oil pump  40 , and an oil supply amount can be optimized. 
   Moreover, the compression member  89  is formed integrally with the upper part of the rotary shaft  5 , and disposed in the cylinder  78 . This compression member  89  is rotated by the rotary shaft  5  to compress a fluid (refrigerant) sucked from the suction port  27  and discharge the fluid into the sealed container  1  via the discharge port  28 , and has a substantially columnar shape concentric to the rotary shaft  5  as a whole. 
   Furthermore, the upper surface  93  (one surface) of the compression member  89  crossing an axial direction of the rotary shaft  5  exhibits an inclined shape which extends from a highest top dead center to a lowest bottom dead center to return to the top dead center and which is continuous between the top dead center and the bottom dead center. 
   One surface of the compression member  89  having the continuously inclined shape is disposed on the upper surface  93  which is a surface on a side opposite to the driving element  2  stored in the lower part of the sealed container  1  of the compression member  89 . 
   On the other hand, the vane  11  is disposed between the suction port  27  and the discharge port  28 , and abuts on the upper surface  93  of the compression member  89  to partition the compression space  21  of the cylinder  78  into a low pressure chamber LR and a high pressure chamber HR. The coil spring  18  always urges the vane  11  toward the upper surface  93 . 
   A lower opening of the cylinder  78  is closed by the sub-support member  79 , and a space  54  is formed between the lower surface (the other surface) of the compression member  89  and the main support member  79  (on a back-surface side of the compression space  21 ). This space  54  is a space sealed by the compression member  89  and the main support member  79 . Moreover, a slight amount of the refrigerant flows from the compression space  21  into the space  54  via a clearance between the compression member  89  and the cylinder  78 . Therefore, the pressure of the space  54  is set to a value (intermediate pressure) which is higher than that of a low-pressure refrigerant sucked into the suction port  27  and which is lower than that of a high-pressure refrigerant in the sealed container  1 . 
   When the pressure of the space  54  is set to the intermediate pressure in this manner, it is possible to avoid a disadvantage that the compression member  89  is strongly pushed upward by the pressure of the space  54  and that the upper surface  93  of the compression member  89  as a receiving surface, and the lower surface  84 A of the projected part  84  are remarkably worn. Consequently, durability of the upper surface  93  of the compression member  89  can be improved. 
   Furthermore, when the pressure of the space  54  on the other surface side of the compression member  89  is set to the intermediate pressure, the pressure of the space  54  is lower than that in the sealed container  1 . Therefore, it is possible to supply the oil smoothly to the compression member  89  which is a peripheral portion of the space  54 , or the vicinity of the main bearing  13  utilizing the pressure difference. 
   On the other hand, the back pressure chamber  17  is not set to the high pressure unlike a conventional technology. The pressure of the back pressure chamber  17  as the sealed space is set to a value which is higher than that of the pressure of the refrigerant sucked into the suction port  27  and which is lower than that of the pressure in the sealed container  1 . In the conventional technology, a part of the back pressure chamber  17  is allowed to communicate with the inside of the sealed container  1 , and the inside of the back pressure chamber  17  is set to a high pressure to urge the vane  11  downward in addition to the coil spring  18 . However, in the present embodiment, the compression element  3  is positioned in the upper part of the sealed container  1 . Therefore, when the back pressure chamber  17  is set to the high pressure, the oil supplied to the vicinity of the vane  11  might be insufficient. 
   Here, the back pressure chamber  17  is formed into a sealed space without being allowed to communicate with the inside of the sealed container  1 . Accordingly, the refrigerant only slightly flows into the back pressure chamber  17  from low and high pressure chamber sides of the compression space  21  via the gap of the vane  11 . Therefore, the back pressure chamber  17  has an intermediate pressure which is higher than the pressure of the refrigerant sucked into the suction port  27  and which is lower than the pressure inside the sealed container  1 . Accordingly, since the pressure inside the back pressure chamber  17  is lower than that in the sealed container  1 , the oil rises through the oil passage  42  in the rotary shaft  5  utilizing the pressure difference, and the oil can be supplied from the oil holes  44 ,  45  to the peripheral portion of the vane  11 . 
   Consequently, even when the compression element  3  is disposed in the upper part of the sealed container  1 , the oil can be smoothly supplied to sliding portions such as the compression member  89  and the vane  11 , and reliability of the compressor C can be improved. 
   Moreover, a very small clearance is formed between a peripheral side face of the compression member  89  and an inner wall of the cylinder  78 , whereby the compression member  89  freely rotates. The clearance between the peripheral side face of the compression member  89  and the inner wall of the cylinder  78  is also sealed with oil. 
   The discharge valve  12  is mounted on an outer side of the discharge port  28  to be positioned in a side face of the compression space  21  of the cylinder  78 , and a discharge pipe  95  is formed in the cylinder  78  and the support member  77  in such a manner as to allow the discharge valve  12  to communicate with the upper part of the sealed container  1 . That is, the refrigerant compressed in the cylinder  78  is discharged from the discharge port  28  into the upper part of the sealed container  1  via the discharge valve  12  and the discharge pipe  95 . 
   Moreover, a through hole  120  extending through the cylinder  78  and the support member  77  in the axial center direction (vertical direction) is formed in a position substantially symmetric with the discharge valve  12  in the cylinder  78  and the support member  77 . A discharge pipe  38  is attached to a position corresponding to a lower portion under the through hole  120  in the side surface of the sealed container  1 . The refrigerant discharged from the discharge pipe  95  to the upper part of the sealed container as described above passes through the through hole  120 , and is discharged from the discharge pipe  38  to the outside of the compressor C. It is to be noted that the oil pump  40  is disposed on a lower end of the rotary shaft  5 , and one end of the pump is immersed in the oil reservoir  36  in a bottom part of the sealed container  1 . Moreover, the oil pumped up by the oil pump  40  is supplied to the sliding portion or the like of the compression element  3  via the oil passage  42  formed in the center of the rotary shaft  5  and the oil holes  44 ,  45  formed ranging from the oil passage  42  to the side surface of the compression element  3  in the axial direction of the rotary shaft  5 . In the sealed container  1 , a predetermined amount of, for example, carbon dioxide (CO 2 ), R-134a, or HC-based refrigerant is sealed in. 
   According to the aforementioned constitution, when power is supplied to the stator coil of the stator  4  of the driving element  2 , the rotor  6  is rotated clockwise (seen from the bottom). The rotation of the rotor  6  is transmitted through the rotary shaft  5  to the compression member  89 , whereby the compression member  89  is rotated clockwise in the cylinder  78  (seen from the bottom). Now, it is assumed that the top dead center of the upper surface  93  of the compression member  89  is on the vane  11  side of the discharge port  28 , and the refrigerant in a refrigerant circuit is sucked from the suction port  27  through the suction pipe  26  and the suction passage  24  into a space (low pressure chamber) surrounded with the cylinder  78 , the support member  77 , the compression member  89  and the vane  11  on the suction port  27  side of the vane  11 . 
   Moreover, when the compression member  89  is rotated in this state, a volume of the space is narrowed due to inclination of the upper surface  93  from a stage at which the top dead center passes through the vane  11  and the suction port  27 , and the refrigerant in a space (high pressure chamber) is compressed. Then, the refrigerant compressed until the top dead center passes through the discharge port  28  is continuously discharged from the discharge port  28 . On the other hand, after the passage of the top dead center through the suction port  27 , the volume of the space (low pressure chamber) surrounded with the cylinder  78 , the support member  79 , the compression member  89 , and the vane  11  on the suction port  27  side of the vane  11  is expanded. Accordingly, the refrigerant is sucked from the refrigerant circuit through the suction pipe  26 , the suction passage  24 , and the suction port  27  into the compression space  21 . 
   The refrigerant is discharged from the discharge port  28  through the discharge valve  12  and the discharge pipe  95  into the upper part of the sealed container  1 . Then, the high-pressure refrigerant discharged into the sealed container  1  passes through the upper part of the sealed container  1 , and is discharged through the communication hole  120  formed in the support member  77  and the cylinder  78  into the refrigerant circuit via the discharge pipe  38 . On the other hand, the separated oil flows down through the communication hole  120 , and further flows down from between the sealed container  1  and the stator  4  to return into the oil reservoir  36 . 
   It is to be noted that in the present embodiment, the back pressure chamber  17  is formed into the sealed space, and the pressure of the back pressure chamber  17  applied as the back pressure of the vane  11  is set to a value which is higher than that of the pressure of the refrigerant sucked into the suction port  27  and which is lower than that of the pressure in the sealed container  1 . The present invention is not limited to a case where the back pressure chamber  17  is formed into the sealed space in this manner. For example, the back pressure chamber  17  may communicate with the inside of the sealed container  1  via a small passage (nozzle). In this case, since the refrigerant flows from the sealed container  1  through the nozzle into the back pressure chamber  17 , the pressure of the refrigerant drops while the refrigerant passes through the nozzle. Accordingly, the back pressure chamber  17  has a value which is higher than that of the pressure of the refrigerant sucked into the suction port  27  and which is lower than that of the pressure in the sealed container  1 . Therefore, the oil can be smoothly supplied to the peripheral portion of the vane  11  utilizing the pressure difference. When a diameter of the nozzle is adjusted, the pressure of the refrigerant flowing into the back pressure chamber  17  can be freely set. 
   Moreover, in the same manner as in the back pressure chamber  17 , the space  54  as the sealed space on the other surface side of the compression member  89  has an intermediate pressure which is higher than the pressure of the low-pressure refrigerant sucked into the suction port  27  and which is lower than the pressure of the high-pressure refrigerant in the sealed container  1 . However, the space  54  may be allowed to communicate with the inside of the sealed container  1  via the small passage (nozzle). In this case, since the refrigerant flows from the sealed container  1  through the nozzle into the space  54 , the pressure of the refrigerant drops while the refrigerant passes through the nozzle. Accordingly, the space  54  indicates a value which is higher than that of the pressure of the refrigerant sucked into the suction port  27  and which is lower than that of the pressure in the sealed container  1 . Therefore, it is possible to avoid a disadvantage that the upper surface  93  of the compression member  89  which is the receiving surface, and the lower surface  84 A of the projected part  84  are remarkably worn. Consequently, the durability of the upper surface  93  of the compression member  89  can be improved. Furthermore, when the space  54  is set to such intermediate pressure, it is possible to supply the oil smoothly to the compression member  89  which is the peripheral portion of the space  54 , or the vicinity of the main bearing  13  utilizing the pressure difference. When the diameter of the nozzle is adjusted, the pressure of the refrigerant flowing into the space  54  can be freely set. 
   Furthermore, in the present embodiment, the bearings of the rotary shaft  5  are disposed in three places: the upper part (sub-bearing  83 ) and the lower part (main bearing  13 ) of the compression element  3 ; and the lower part (sub-bearing  86 ) of the driving element  2 , but may be disposed in two places: the upper part of the compression element  3  and the lower part of the driving element  2 ; or the lower part of the compression element  3  and the lower part of the driving element  2 . Even in this case, the rotary shaft  5  can be sufficiently supported. 
   Second Embodiment 
   Next, a second embodiment of the present invention will be described with reference to  FIGS. 5 to 7 .  FIGS. 5 to 7  are vertical sectional side views of a compressor C in this case, and the respective figures show different sections, respectively. It is to be noted that in  FIGS. 5 to 7 , components denoted with the same reference numerals as those of  FIGS. 1 to 4  produce similar effects, and description thereof is therefore omitted. 
   In the present embodiment, a driving element  2  is disposed in an upper part of a sealed container  1 , and a compression element  3  is disposed in a lower part of the container. That is, the compression element  3  is disposed below the driving element  2 . 
   The compression element  3  comprises a main support member  107  fixed to an inner wall of the sealed container  1 ; a cylinder  108  attached to an underside of the main support member  107  by bolts; a compression member  109 , a vane  11 , and a discharge valve  12  arranged in the cylinder  108 ; a sub-support member  110  attached to an underside of the cylinder  108  via bolts and the like. An upper surface central portion of the main support member  107  concentrically projects upward, and a main bearing  13  of a rotary shaft  5  is formed therein. An outer peripheral edge of the main bearing rises in an axial center direction (upward direction), and the raised outer peripheral edge is fixed to the inner wall of the sealed container  1  as described above. 
   Moreover, an upper opening of the cylinder  108  is closed by the main support member  107 , and accordingly a sealed space  115  closed by the compression member  109  and the main support member  107  is formed between the upper surface (the other surface) of the compression member  109  disposed in the cylinder  108  and the main support member  107  (the other surface side of the compression member  109 ). 
   The sub-support member  110  comprises a main body, a sub-bearing  23  extended through a center of the main body, and a projected part  112  fixed to the upper surface central portion of the sub-support member by bolts. An upper surface  112 A of the projected part  112  is formed into a smooth surface. 
   Moreover, a lower opening of the cylinder  108  is closed by the projected part  112  of the sub-support member  110 , and accordingly a compression space  21  is formed inside the cylinder  108  (the inside of the cylinder  108  between the compression member  109  and the projected part  112  of the sub-support member  110 ). 
   A slot  16  is formed in the projected part  112  of the sub-support member  110 , and the vane  11  is inserted into this slot  16  to reciprocate up and down. A back pressure chamber  17  is formed in a lower part of the slot  16 , and a coil spring  18  is arranged as urging means in the slot  16  to urge the lower surface of the vane  11  upward. 
   Moreover, a suction passage  24  is formed in the cylinder  108  and the projected part  112  of the sub-support member  110 , and a suction pipe (not shown) is mounted in the sealed container  1 , and connected to one end of the suction passage  24 . A suction port  27  and a discharge port  28  which communicate with the compression space  21  are formed in the cylinder  108 , and the other end of the suction passage  24  communicates with the suction port  27 . The vane  11  is positioned between the suction port  27  and the discharge port  28 . 
   The rotary shaft  5  is rotatably supported by the main bearing  13  formed on the main support member  107  and the sub-bearing  23  formed on the sub-support member  110 . That is, the rotary shaft  5  is inserted into centers of the main support member  107 , the cylinder  108 , and the sub-support member  110 , and its central portion of an up-and-down direction is rotatably supported by the main bearing  13 . A lower end of the rotary shaft is rotatably supported by the sub-bearing  23  of the sub-support member  110 . Moreover, the compression member  109  is formed integrally in a position below the center of the rotary shaft  5 , and disposed in the cylinder  108 . 
   This compression member  109  is disposed in the cylinder  108 , and rotated by the rotary shaft  5  to compress a fluid (refrigerant in the present embodiment) sucked from the suction port  27  and discharge the fluid from the discharge port  28  into the sealed container  1  via the discharge valve  12  and the discharge pipe  95 . The member has a substantially columnar shape concentric to the rotary shaft  5  as a whole. The compression member  109  has a shape in which a thick part on one side is continuous with a thin part on the other side, and a lower surface  113  (one surface) crossing an axial direction of the rotary shaft  5  is an inclined surface which is low in the thick part and high in the thin part. That is, the lower surface  113  has an inclined shape which extends from a highest top dead center to a lowest bottom dead center to return to the top dead center and which is continuous between the top dead center and the bottom dead center (not shown). 
   One surface of the compression member  109  having the continuously inclined shape is disposed on the lower surface  113  which is a surface on a side opposite to the driving element  2  stored above the compression member  109  in the sealed container  1 . 
   Moreover, the discharge pipe  95  of the present embodiment is a pipe which extends from the discharge port  28  onto an oil surface of an oil reservoir  36  in a bottom part of the sealed container  1 . The refrigerant compressed in the cylinder  108  is discharged from the discharge port  28  through the discharge valve  12  and the discharge pipe  95  onto the oil surface in the sealed container  1 . 
   It is to be noted that the shape of the lower surface  113  of the compression member  109  is a shape continuously inclined between the top dead center and the bottom dead center. One surface of the compression member  109  having the continuously inclined shape is disposed on the lower surface  113  which is the surface on the side opposite to the driving element  2  stored above the compression member  109  in the sealed container  1 . 
   On the other hand, the vane  11  is disposed between the suction port  27  and the discharge port  28  as described above, and abuts on the lower surface  113  of the compression member  109  to partition the compression space  21  of the cylinder  108  into a low pressure chamber LR and a high presser chamber HR. The coil spring  18  always urges the vane  11  toward the lower surface  113 . 
   Moreover, the space  115  is a space sealed by the compression member  109  and the main support member  107  as described above. However, since the refrigerant slightly flows from the clearance between the compression member  109  and the cylinder  108  into the space, the space  115  has an intermediate pressure which is higher than the pressure of a low-pressure refrigerant sucked into the suction port  27  and which is lower than the pressure of a high-pressure refrigerant in the sealed container  1 . 
   When the pressure of the space  115  is set to the intermediate pressure in this manner, it is possible to avoid a disadvantage that the compression member  109  is strongly pressed upward by the pressure of the space  115  and that the lower surface  113  of the compression member  109  as the receiving surface, and the upper surface  112 A of the projected part  112  are remarkably worn. Consequently, durability of the lower surface  113  of the compression member  109  can be improved. 
   Moreover, when the pressure of the space  115  on the other surface side of the compression member  109  is set to the intermediate pressure, the pressure in the space  115  becomes lower than that in the sealed container  1 . 
   Therefore, it is possible to supply the oil smoothly to the compression member  109  which is a peripheral portion of the space  115 , or the vicinity of the main bearing  13  utilizing the pressure difference. 
   Furthermore, since the compression space  21  is disposed in the lower surface  113  of the compression member  109  on a side opposite to the driving element  2 , gas leakage from the main bearing  13  is not easily generated, and sealability of the main bearing  13  can be enhanced. Since the sub-bearing  23  on the lower surface  113  side of the compression member  109  forming the compression space  21  is positioned in the oil reservoir  36 , the gas leakage from the sub-bearing  23  can be avoided by the oil. The sealability of the sub-bearing  23  is enhanced, and it is possible to avoid a disadvantage that the peripheral surface of the rotary shaft  5  has a high pressure. Consequently, it is possible to perform the smooth oil supply utilizing the pressure difference. 
   In addition, in the same manner as in the above-described embodiment, the back pressure chamber  17  is not set to the high pressure unlike a conventional technology. The pressure of the back pressure chamber  17  as a sealed space is set to a value which is higher than that of the pressure of the refrigerant sucked into the suction port  27  and which is lower than that of the pressure in the sealed container  1 . Therefore, since the pressure in the back pressure chamber  17  is lower than that in the sealed container  1 , the oil rises through an oil passage  42  in the rotary shaft  5  utilizing the pressure difference, and the oil can be supplied from oil holes formed ranging from the oil passage  42  to a side surface of the compression member  109  in an axial direction of the rotary shaft  5  to the peripheral portion of the vane  11 . 
   Moreover, a very small clearance is formed between a peripheral side face of the compression member  109  and an inner wall of the cylinder  108 , whereby the compression member  109  freely rotates. The clearance between the peripheral side face of the compression member  109  and the inner wall of the cylinder  108  is also sealed with oil. 
   Furthermore, the discharge valve  12  is mounted to an outer side of the discharge port  28  to be positioned in a side face of the compression space  21  of the cylinder  108 , and a discharge pipe  95  is formed externally with respect to the discharge valve  12  in the cylinder  108  and the main support member  107 . An upper end of the discharge pipe  95  opens in the oil surface in the oil reservoir  36 . 
   In this manner, the refrigerant gas discharged from the discharge port  28  is passed through the discharge pipe  95 , and guided onto the oil surface, so that pulsations of the discharged refrigerant can be reduced. 
   As described above in detail, even in the present embodiment, the oil can be smoothly supplied to sliding portions such as the compression member  109  and the vane  11 , and reliability of the compressor C can be improved. In the first embodiment, the bearings of the rotary shaft  5  are disposed in three places: the upper part (sub-bearing  83 ) of the compression element  3 ; the lower part (main bearing  13 ) of the element; and the lower part (sub-bearing  86 ) of the driving element  2 . However, in the present embodiment, since the rotary shaft  5  can be sufficiently supported by two bearings: the main bearing  13 ; and the sub-bearing  23 , the number of components can be reduced, and the compressor can be inexpensively constituted. 
   It is to be noted that in the present embodiment, in the same manner as in the above-described embodiment, the back pressure chamber  17  is formed into the sealed space, and the pressure of the back pressure chamber  17  applied as the back pressure of the vane  11  is set to a value which is higher than that of the pressure of the refrigerant sucked into the suction port  27  and which is lower than that of the pressure in the sealed container  1 . The present invention is not limited to a case where the back pressure chamber  17  is formed into the sealed space in this manner. For example, the back pressure chamber  17  may communicate with the inside of the sealed container  1  via a small passage (nozzle). In this case, since the refrigerant flows from the sealed container  1  through the nozzle into the back pressure chamber  17 , the pressure of the refrigerant drops while the refrigerant passes through the nozzle. Accordingly, the back pressure chamber  17  has a value which is higher than that of the pressure of the refrigerant sucked into the suction port  27  and which is lower than that of the pressure in the sealed container  1 . Therefore, the oil can be smoothly supplied to the peripheral portion of the vane  11  utilizing the pressure difference. When a diameter of the nozzle is adjusted, the pressure of the refrigerant flowing into the back pressure chamber  17  can be freely set. 
   Moreover, in the same manner as in the back pressure chamber  17 , the space  115  as the sealed space on the other surface side of the compression member  109  has an intermediate pressure which is higher than the pressure of the low-pressure refrigerant sucked into the suction port  27  and which is lower than the pressure of the high-pressure refrigerant in the sealed container  1 . However, the space  115  may be allowed to communicate with the inside of the sealed container  1  via the small passage (nozzle). In this case, since the refrigerant flows from the sealed container  1  through the nozzle into the space  115 , the pressure of the refrigerant drops while the refrigerant passes through the nozzle. Accordingly, the space  115  indicates a value which is higher than that of the pressure of the refrigerant sucked into the suction port  27  and which is lower than that of the pressure in the sealed container  1 . Therefore, it is possible to avoid a disadvantage that the lower surface  113  of the compression member  109  which is a receiving surface, and the upper surface  112 A of the projected part  112  are remarkably worn. Consequently, the durability of the lower surface  113  of the compression member  109  can be improved. Furthermore, when the space  115  is set to such intermediate pressure, it is possible to supply the oil smoothly to the compression member  109  which is the peripheral portion of the space  115 , or the vicinity of the vane  11  utilizing the pressure difference. When the diameter of the nozzle is adjusted, the pressure of the refrigerant flowing into the space  115  can be freely set. 
   Third Embodiment 
   Next,  FIGS. 8 to 10  show a compressor C of a third embodiment of the present invention,  FIGS. 8 to 10  are vertical sectional side views of the compressor C of the third embodiment, and the respective figures show different sections. It is to be noted that in  FIGS. 8 to 10 , components denoted with the same reference numerals as those of  FIGS. 1 to 7  produce similar effects, and description thereof is therefore omitted. 
   In this case, a driving element  2  is disposed in a lower part of a sealed container  1 , and a compression element  3  is disposed in an upper part of the container. A compression space  21  of the compression element  3  is disposed on a lower surface side which is a driving element  2  side of a compression member  109 , and a lower surface (one surface)  113  of the compression member  109  is formed into a shape inclined continuously between an top dead center and a bottom dead center. 
   Moreover, a slot  16  is formed in a main support member  107  and a cylinder  108 , and a vane  11  is inserted into this slot  16  to reciprocate up and down. A back pressure chamber  17  is formed in a lower part of the slot  16 , and a coil spring  18  is arranged as urging means in the slot  16  to urge the lower surface of the vane  11  upward. Moreover, the vane  11  abuts on the lower surface  113  of the compression member  109 , and partitions the compression space  21  in the cylinder  108  into a low pressure chamber and a high pressure chamber. The coil spring  18  always urges the vane  11  toward the lower surface  113 . 
   Moreover, a value of a pressure of the back pressure chamber  17  as a sealed space is set to be higher than that of the pressure of the refrigerant sucked into a suction port  27  and lower than that of the pressure in the sealed container  1  as described above in the respective embodiments. When the back pressure chamber  17  is not allowed to communicate with the inside of the sealed container  1 , and formed into the sealed space, the refrigerant on low and high pressure chamber sides of the compression space  21  only slightly flows from a gap of the vane  11  into the back pressure chamber  17 . Therefore, the back pressure chamber  17  has an intermediate pressure which is higher than the pressure of the refrigerant sucked into the suction port  27  and which is lower than the pressure in the sealed container  1 . Accordingly, since the pressure in the back pressure chamber  17  is lower than that in the sealed container  1 , the oil rises through an oil passage  42  in a rotary shaft  5  utilizing the pressure difference. The oil can be supplied from oil holes  44 ,  45  into a peripheral portion of the vane  11 . 
   On the other hand, a space  115  on the other surface side of the compression member  109  is formed into the space sealed by the compression member  109  and the main support member  107 . Accordingly, since the refrigerant slightly flows from the compression space  21  through the clearance between the compression member  109  and the cylinder  108 , the space  115  has an intermediate pressure which is higher than the pressure of a low-pressure refrigerant sucked into the suction port  27  and which is lower than the pressure of a high-pressure refrigerant in the sealed container  1 . 
   When the pressure of the space  115  is set to the intermediate pressure in this manner, it is possible to avoid a disadvantage that the compression member  109  is strongly pressed upward by the pressure of the space  115  and that the lower surface  113  of the compression member  109  as a receiving surface and the upper surface  112 A of the projection part  112  are remarkably worn. Consequently, the durability of the lower surface  113  of the compression member  109  can be improved. 
   Furthermore, when the pressure of the space  115  on the other surface side of the compression member  109  is set to the intermediate pressure, the pressure of the space  115  is lower than that in the sealed container  1 . Therefore, it is possible to supply the oil smoothly to the compression member  109  which is a peripheral portion of the space  115 , or the vicinity of the main bearing  13  utilizing the pressure difference. 
   It is to be noted that even in the present embodiment, in the same manner as in the above-described embodiments, the back pressure chamber  17  is formed into the sealed space, and the pressure of the back pressure chamber  17  applied as the back pressure of the vane  11  is set to a value which is higher than that of the pressure of the refrigerant sucked into the suction port  27  and which is lower than that of the pressure in the sealed container  1 . The present invention is not limited to a case where the back pressure chamber  17  is formed into the sealed space in this manner. For example, the back pressure chamber  17  may communicate with the inside of the sealed container  1  via a small passage (nozzle). In this case, since the refrigerant flows from the sealed container  1  through the nozzle into the back pressure chamber  17 , the pressure of the refrigerant drops while the refrigerant passes through the nozzle. Accordingly, the back pressure chamber  17  has a value which is higher than that of the pressure of the refrigerant sucked into the suction port  27  and which is lower than that of the pressure in the sealed container  1 . Therefore, the oil can be smoothly supplied to the peripheral portion of the vane  11  utilizing the pressure difference. When a diameter of the nozzle is adjusted, the pressure of the refrigerant flowing into the back pressure chamber  17  can be freely set. 
   Moreover, in the same manner as in the back pressure chamber  17 , the space  115  as the sealed space on the other surface side of the compression member  109  has an intermediate pressure which is higher than the pressure of the low-pressure refrigerant sucked into the suction port  27  and which is lower than the pressure of the high-pressure refrigerant in the sealed container  1 . However, the space  115  may be allowed to communicate with the inside of the sealed container  1  via the small passage (nozzle). In this case, since the refrigerant flows from the sealed container  1  through the nozzle into the space  115 , the pressure of the refrigerant drops while the refrigerant passes through the nozzle. Accordingly, the space  115  indicates a value which is higher than that of the pressure of the refrigerant sucked into the suction port  27  and which is lower than that of the pressure in the sealed container  1 . Therefore, it is possible to avoid a disadvantage that the lower surface  113  of the compression member  109  which is the receiving surface, and the upper surface  112 A of the projected part  112  are remarkably worn. Consequently, the durability of the lower surface  113  of the compression member  109  can be improved. Furthermore, when the space  115  is set to such intermediate pressure, it is possible to supply the oil smoothly to the compression member  109  which is the peripheral portion of the space  115 , or the vicinity of the main bearing  13  utilizing the pressure difference. When the diameter of the nozzle is adjusted, the pressure of the refrigerant flowing into the space  115  can be freely set. 
   It is to be noted that in the above-described embodiments, there has been described examples of the compressor which is used in the refrigerant circuit of the refrigerator and which compresses the refrigerant, but the present invention is not limited to the embodiments. The present invention is effective even when applied to a so-called air compressor for sucking, compressing, and discharging air.