Patent Publication Number: US-2017350391-A1

Title: Gas compressor

Description:
TECHNICAL FIELD 
     The present invention relates to a so-called vane rotary-type gas compressor. 
     BACKGROUND ART 
     Conventionally, various gas compressors have been proposed as indicated in Patent Literature 1. 
       FIG. 16  shows a compression block disposed in a gas compressor pertaining to Patent Literature 1. 
     This compression block has a cylinder block  100  and a pair of side blocks  101  disposed on the left and right of the cylinder block  100 . A cylinder chamber  105  is formed in the cylinder block  100  and the pair of the side blocks  101 . The cylinder block  100  is provided with a suction port  110  and two discharge ports  108 . 
     A rotor  102  is rotatably disposed in the cylinder chamber  105 . The rotor  102  is formed with a plurality of vane grooves  106  at intervals. A vane  103  is disposed in each vane groove  106  so as to freely retractable from an outer peripheral surface of the rotor  102 . A back pressure space  107  ( 107 A,  107 B and  107 C) is formed in the vane groove  106  on the back surface side of the vane  103 . The back pressure space  107  opens to both side surfaces of the rotor  102 . 
     An intermediate-pressure supply groove  113  and a high-pressure supply groove  114  are formed in a wall surface on the cylinder chamber  105  side of each side block  101 , on a rotation locus of the back pressure space  107 . An intermediate pressure that is a pressure higher than that of a sucked refrigerant and is lower than that of the discharged refrigerant is supplied to the intermediate-pressure supply groove  113 . High pressure that is a pressure equivalent to that of the discharged refrigerant is supplied to the high-pressure supply groove  114 . 
     Compression chambers  105   a ,  105   b  and  105   c  are formed in the cylinder chamber  105  by being surrounded by the two vanes  103 . The compression chambers  105   a ,  105   b  and  105   c  perform a suction process, a compression process and a discharged process and repeat this series of the processes, at the time of rotation of the rotor  102 . 
     In the suction process, the refrigerant is sucked from the suction port  110  by gradual increase in volumes of the compression chambers  105   a ,  105   b  and  105   c . In the compression process, the refrigerant is compressed by gradual decrease in volumes of the compression chambers  105   a ,  105   b  and  105   c . In the discharged process, when the volumes of the compression chambers  105   a ,  105   b  and  105   c  are gradually decreased and a refrigerant pressure becomes at least a predetermined pressure, an open/close valve  109  opens and the refrigerant is discharged from the discharge port  108 . 
     In such a series of processes, as to each of the vane  103 , although the refrigerant pressures in the compression chambers  105   a ,  105   b  and  105   c  press each of the vanes  103  in a direction (hereinafter, a “storage direction”) in which each of the vane  103  is stored in the vane groove  106 , a tip of each of the vane  103  slides along an inner wall of the cylinder chamber  105  by a back pressure acting on the back pressure space  107  and thereby the compression chambers  105   a ,  105   b  and  105   c  are able to reliably compress the refrigerant. 
     Here, in the suction process and in an early stage of the compression process in which pressure in the storage direction is small, an intermediate pressure from the intermediate-pressure supply groove  113  is made to act as the back pressure. In addition, in a later stage of the compression process and in the discharged process in which the pressure in the storage direction of the vane  103  is large, high pressure from the high-pressure supply groove  114  is made to act as the back pressure. In this way, a sliding resistance of the vane  103  is made as small as possible so as to achieve low fuel consumption by changing the back pressure made to act on the vane  103 , in accordance with the pressure in the storage direction of the vane  103 . 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Laid-Open Publication No. 2013-194549 
     SUMMARY OF INVENTION 
     Technical Problem 
       FIG. 17  is a graph showing changes in a pressure P 105   a  in the compression chamber  105   a , a pressure P 105   b  in the compression chamber  105   b  and a pressure P 107 A in the back pressure space  107 A in accordance with a rotation angle of the rotor. As shown in  FIG. 17 , at an angle of 180 degrees, the back pressure space  107 A having completed communication with the intermediate-pressure supply groove  113  communicates with the high-pressure supply groove  114 . 
     In the example shown in  FIG. 16 , when the back pressure space  107 B shifts a communication state from the intermediate-pressure supply groove  113  to the high-pressure supply groove  114 , the preceding rotation downstream back pressure space  107 A is already in communication with the high-pressure supply groove  114 . Accordingly, when the following rotation upstream back pressure space  107 B completes shifting of the communication state to the high-pressure supply groove  114 , the two back pressure spaces  107 A and  107 B are simultaneously brought into a state of communicating with the high-pressure supply groove  114 . 
     Since the pressure P 107 B in the rotation upstream back pressure space  107 B is intermediate pressure, the pressure P 107 A in the rotation downstream back pressure space  107 A that communicates with the rotation upstream back pressure space  107 B via the high-pressure supply groove  114  becomes temporarily lower than a pressure to be supplied to the high-pressure supply groove  114  as shown by P in  FIG. 17 . Since, in the vane  103  on the rotation downstream side, the pressures of the refrigerant in the compression chambers  105   a ,  105   b  and  105   c  which are in the later stage of the compression process and in the discharged process act in the storage direction of the vane  103 , there is a possibility that the vane  103  may be temporarily stored in the vane groove  106  and chattering may occur. 
     The present invention has been made in view of the above-mentioned circumstances and an object of the present invention is to prevent occurrence of chattering of the vane by a temporary reduction in pressure in the back pressure space of the vane, for example, in the later stage of the compression process and in the discharged process, and to maintain operating performance as a gas compressor. 
     Solution to Problem 
     In order to achieve the above-mentioned object, a gas compressor of the present invention includes: 
     a tubular cylinder block having therein a cylinder chamber in which a refrigerant is compressed; 
     side blocks that are attached to side parts of the cylinder block and seal an opening of the cylinder chamber on the side parts; 
     a rotor that rotates in the cylinder chamber and has a plurality of vane grooves opening to an outer peripheral surface facing an inner peripheral surface of the cylinder chamber at intervals in a rotation direction; 
     a plurality of vanes that is respectively stored in the respective vane grooves, protrudes and retracts from the outer peripheral surface, comes into sliding contact with the inner peripheral surface of the cylinder chamber, and partitions a space between the inner peripheral surface and the outer peripheral surface of the rotor into a plurality of compression chambers; 
     an intermediate-pressure supply section that is formed in at least one of the side blocks, communicates with a back pressure space at a groove bottom of each of the vane grooves storing the vanes for partitioning the compression chambers from a suction process to a compression process, and supplies, to the back pressure space, an intermediate pressure larger than a refrigerant pressure in each of the compression chambers from the suction process to the compression process; and 
     a high-pressure supply section that is formed in at least one of the side blocks, communicates with the back pressure space in each of the vane grooves storing the vanes for partitioning the compression chambers from the compression process to a discharged process after communication with the intermediate-pressure supply section has been completed, and supplies, to the back pressure space, high pressure larger than the refrigerant pressure in each of the compression chambers from the compression process to the discharged process and larger than the intermediate pressure, wherein 
     the high-pressure supply section is divided into a plurality of mutually independent supply sections in the rotation direction, 
     the second supply section that is positioned at least secondarily from the most upstream side in the rotation direction is formed into a shape in which the second supply section, while communicating with the back pressure space of one vane groove, does not simultaneously communicate with the back pressure space of the other vane groove adjacent to the vane groove on the upstream side in the rotation direction, and the high-pressure supply section is formed in a range in which it simultaneously communicates with the back pressure space of the one vane groove and the back pressure space of the other vane groove adjacent to the vane groove on the upstream side in the rotation direction. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional diagram showing an overall configuration of a vane rotary-type gas compressor according to a first embodiment of the present invention. 
         FIG. 2  is a cross-sectional diagram along the I-I line of the gas compressor in  FIG. 1 . 
         FIG. 3  is a cross-sectional diagram along the II-II line of the gas compressor in  FIG. 1 . 
         FIG. 4  is an explanatory diagram showing essential parts of a compression block shown in  FIG. 3 , in an enlarged manner. 
         FIG. 5  is an explanatory diagram showing a virtual example of a case where a first supply section and a second supply section of a high-pressure supply groove in  FIG. 3  are disposed apart from each other at an interval at which a back pressure space of a vane groove does not communicate with any of them. 
         FIG. 6  is a graph showing changes in pressure in the compression chamber and pressure in the back pressure space of the vane in the vane groove in  FIG. 5 , in accordance with a rotation angle of a rotor. 
         FIG. 7  is an explanatory diagram showing a communication cross-sectional area between the first supply section of the high-pressure supply groove and the back pressure space in the vane groove, and a communication cross-sectional area between the second supply section of the high-pressure supply groove and the back pressure space in the vane groove, in  FIG. 3 . 
         FIG. 8  is a graph showing changes in the pressure in the compression chamber and the pressure in the back pressure space of the vane in the vane groove in  FIG. 3  in accordance with the rotation angle of the rotor. 
         FIG. 9  is a cross-sectional diagram of a vane rotary-type gas compressor according to a second embodiment of the present invention, at a position corresponding to the cross-sectional diagram in  FIG. 2 . 
         FIG. 10  is a cross-sectional diagram of the vane rotary-type gas compressor according to the second embodiment of the present invention, at a position corresponding to the cross-sectional diagram in  FIG. 3 . 
         FIG. 11  is an explanatory diagram showing essential parts of a compression block shown in  FIG. 10  in an enlarged manner. 
         FIG. 12  is an explanatory diagram showing a positional relation between a region in which a projection stroke of the vane relative to the vane groove is reduced at a rate equal to or more than a constant level and an interval between the first supply section and the second supply section in the compression block shown in  FIG. 10 . 
         FIG. 13  is a graph showing changes in the pressure in the compression chamber and the pressure in the back pressure space in the vane groove in  FIG. 12  in accordance with the rotation angle of the rotor. 
         FIG. 14  is an explanatory diagram showing a positional relation, during a period when the vane is in sliding contact with a region in which the projection stroke of the vane relative to the vane groove is reduced at a rate equal to or more than a constant level, between the region concerned and an interval between the first supply section and the second supply section, in the compression block shown in  FIG. 10 . 
         FIG. 15  is a graph showing changes in the pressure in compression chamber and the pressure in the back pressure space of the vane in the vane groove in  FIG. 10  in accordance with the rotation angle of the rotor. 
         FIG. 16  is an explanatory diagram showing an inside of a compression block of a conventional gas compressor. 
         FIG. 17  is a graph showing changes in pressure in a compression chamber and pressure in a back pressure space of a vane in a vane groove in  FIG. 16  in accordance with the rotation angle of the rotor. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     The first embodiment of the present invention will be described with reference to  FIG. 1  to  FIG. 8 . 
     As shown in  FIG. 1 , a gas compressor  1  according to the present embodiment includes a substantially cylindrical housing  2 , a compression section  3  stored in the housing  2 , a motor section  4  that transmits driving force to the compression section  3  and an inverter section  5  which is fixed to the housing  2  and which controls driving of the motor section  4 . 
     The housing  2  is configured by a front head  7  in which a not shown suction port is formed and a bottomed cylindrical rear case  9  whose opening is closed by the front head  7 . 
     The compression section  3  is fixed to an inner wall  13  of the rear case  9 . The compression section  3  is formed with a suction chamber  11  on one side and is formed with a discharge chamber  15  on the other side so as to partition the inside of the housing  2 . In addition, a not shown discharge port which communicates the discharge chamber  15  with a refrigerating cycle is formed in an outer periphery of the rear case  9 . Additionally, an oil sump  17  which stores an oil O for maintaining lubricity of the compression section  3  is formed under the discharge chamber  15 . 
     The compression section  3  includes a compression block  19  that forms a cylinder chamber  33 , an oil separator  21  fixed to the compression block  19 , a rotor  23  that is rotatably stored in the cylinder chamber  33 , a vane  25  (refer to  FIG. 3 ) that protrudes and retracts from the rotor  23  to partition the cylinder chamber  33 , and a drive shaft  27  that is fixed integrally with the rotor  23  to transmit the driving force thereto. 
     The compression block  19  is configured by a cylinder block  29 , a pair of side blocks  31 , and the cylinder chamber  33  formed on an inner periphery of the cylinder block  29 . 
     As shown in  FIG. 3 , the cylinder block  29  has the distorted elliptical cylinder chamber  33  therein. An opening of this cylinder chamber  33  is closed by holding both ends of the cylinder block  29  by the pair of the side blocks  31 . 
     As shown in  FIG. 3  and  FIG. 4 , the rotor  23  is disposed such that one place is in contact with an inner wall of the cylinder chamber  33 , is disposed with a position displaced from the center (the center of gravity) of the cylinder chamber  33  being set as the center of rotation, and is provided with a vane groove  75  that opens to an outer peripheral surface of the rotor  23 , and a back pressure space  77  on the back surface side of the vane  25 . 
     The cylinder chamber  33  is partitioned into a plurality of pieces in a rotation direction X of the rotor  23  by the plurality of vanes  25  that protrudes and retracts from the plurality of vane grooves  75  in the rotor  23 . Thereby, a plurality of compression chambers  33   a ,  33   b  and  33   c  is formed between an inner peripheral surface  33   d  of the cylinder chamber  33  and an outer peripheral surface  23   a  of the rotor  23 . 
     In addition, the cylinder block  29  is provided with a suction slot  39  through which the refrigerant is sucked into the cylinder chamber  33 , a discharge slot  35  through which the refrigerant having been compressed in the cylinder chamber  33  is discharged, an open/close valve  37  which opens/closes the discharge slot  35  and a cylinder-side oil supply path  41  which communicates with an oil supply path of the side block  31 . 
     As shown in  FIG. 1 , the pair of the side blocks  31  are configured by a front-side block  31   a  and a rear-side block  31   b  and the oil separator  21  is fixed to the rear-side block  31   b.    
     The front-side block  31   a  is provided with a front-side end surface  43  that abuts on the cylinder block  29 , a not shown suction slot that communicates with the suction slot  39  and sucks the refrigerant from the suction chamber  11 , a front-side bearing  47  that rotatably supports the drive shaft  27  and a front-side oil supply path  49  that communicates with the cylinder-side oil supply path  41 . 
     The front-side end surface  43  is provided with a pressure supply groove, and the pressure supply groove includes an intermediate-pressure supply groove  51  that supplies, to the back pressure space  77 , an intermediate pressure (a middle pressure) higher than that of the sucked refrigerant and lower than that of the discharged refrigerant and a high-pressure supply groove  53  that is provided at a position facing a high-pressure supply groove  69  on the rear-side block  31   b  side. 
     In addition, the front-side bearing  47  is formed with an annular front-side annular groove  55 , which is provided in communication with the one-end side of the front-side oil supply path  49 . Note that the other-end side of the front-side oil supply path  49  is in communication with the cylinder-side oil supply path  41 . 
     As shown in  FIG. 2 , the rear-side block  31   b  includes a rear-side end surface  57  that abuts on the cylinder block  29 , an oil supply hole  59  through which the oil O stored under the discharge chamber  15  is sucked, a rear-side bearing  63  that rotatably supports the drive shaft  27 , and a rear-side oil supply path  59   b  that communicates with the cylinder-side oil supply path  41 . 
     The rear-side end surface  57  includes a discharge hole  61  through which the refrigerant having been compressed in the cylinder chamber  33  is discharged, an intermediate-pressure supply groove  67  (corresponding to an intermediate-pressure supply section in the claims) which supplies, to the back pressure space  77 , the oil of intermediate pressure higher than pressure (suction pressure) of the sucked refrigerant and lower than pressure (discharged pressure) of the discharged refrigerant, and the high-pressure supply groove  69  (corresponding to a high-pressure supply section in the claims) which supplies, to the back pressure space  77 , the oil of high pressure that is the pressure (the discharge pressure) of the discharged refrigerant. 
     The high-pressure supply groove  69  is divided into mutually independent first supply section  69   a  (corresponding to an upstream-side supply section) and second supply section  69   b  (corresponding to a downstream-side supply section) in the rotation direction X of the rotor  23 . 
     In addition, high-pressure supply paths  71   a  and  71   b  respectively open to the first supply section  69   a  and the second supply section  69   b , and the respective high-pressure supply paths  71   a  and  71   b  are in communication with a rear-side annular groove  73  on their one-end sides and are in communication with the first supply section  69   a  and the second supply section  69   b , respectively, on their other-end sides. 
     Note that the high-pressure supply groove  53  of the front-side block  31   a  facing the high-pressure supply groove  69  is also divided into two supply sections (not shown) which are similar to the first supply section  69   a  and the second supply section  69   b.    
     The back pressure space  77  (refer to  FIG. 3  and  FIG. 4 ) formed in the rotor  23  communicates with the intermediate-pressure supply grooves  51  and  67  at a compression first-half position and communicates with the high-pressure supply grooves  53  and  69  at a compression later-half position, by rotation of the rotor  23 . 
     In a state shown in  FIG. 4 , a back pressure space  77 B of the vane groove  75  in a vane  25 B which partitions the compression chamber  33   b  having moved from a suction process to a compression process and the compression chamber  33   a  that is positioned on the downstream side of the compression chamber  33   b  in the rotation direction X of the rotor  23  and has moved from the compression process to a discharged process by rotation of the rotor  23  terminates communication with the intermediate-pressure supply groove  67 . Then, the back pressure space  77 B is about to communicate with the first supply section  69   a  that is positioned on the upstream side of the rotation direction X of the rotor  23 , from now on. 
     In this state, a back pressure space  77 A of the vane groove  75  in a vane  25 A that precedes the vane  25 B in the downstream side of the vane  25 B in the rotation direction X of the rotor  23  has already completed communication with the first supply section  69   a  and is in communication with the second supply section  69   b  positioned on the downstream side in the rotation direction X. 
     In addition, in the rotation direction X of the rotor  23 , the first supply section  69   a  is formed into a shape in which the back pressure space  77 A of the preceding vane  25 A and the back pressure space  77 B of the next vane  25 B that follows the vane  25 A do not communicate with the first supply section  69   a  simultaneously. Namely, in the rotation direction X of the rotor  23 , the first supply section is formed such that an angle range in which the first supply section  69   a  extends becomes smaller than a difference between the angle at which the back pressure space  77 A is positioned and the angle at which the back pressure space  77 B is positioned. In short, a distance between the back pressure space  77 A and the back pressure space  77 B in the rotation direction X of the rotor  23  is set larger than a width of the first supply section  69   a.    
     In a similar way, in the rotation direction X of the rotor  23 , the second supply section  69   b  is formed into a shape in which the back pressure space  77 A of the preceding vane  25 A and the back pressure space  77 B of the next vane  25 B that follows the vane  25 A do not communicate with the second supply section  69   b  simultaneously. Namely, in the rotation direction X of the rotor  23 , the second supply section is formed such that an angle range in which the second supply section  69   b  extends becomes smaller than the difference between the angle at which the back pressure space  77 A is positioned and the angle at which the back pressure space  77 B is positioned. In short, the distance between the back pressure space  77 A and the back pressure space  77 B in the rotation direction X of the rotor  23  is set larger than a width of the second supply section  69   b.    
     As described above, restrictions are caused on the angle range in which the first supply section  69   a  extends and the angle range in which the second supply section  69   b  extends, on the basis of the difference between the angle at which the back pressure space  77 A is positioned and the angle at which the back pressure space  77 B is positioned. 
     Similarly, restrictions are caused on the angle range in which the first supply section  69   a  extends and the angle range in which the second supply section  69   b  extends, on the basis of a difference between the angle at which the back pressure space  77 B is positioned and an angle at which a back pressure space  77 C is positioned. 
     Likewise, restrictions are caused on the angle range in which the first supply section  69   a  extends and the angle range in which the second supply section  69   b  extends, on the basis of a difference between the angle at which the back pressure space  77 C is positioned and the angle at which the back pressure space  77 A is positioned. 
     In this way, the shapes of the first supply section  69   a  and the second supply section  69   b  are determined on the basis of the angle at which the back pressure space  77  is positioned in the rotation direction X of the rotor  23 . 
     Note that a distance between the intermediate-pressure supply groove  67  and the first supply section  69   a  and a distance between the second supply section  69   b  and the intermediate-pressure supply groove  67  in the rotation direction X of the rotor  23  are set larger than a width of the back pressure space  77  in the rotation direction X of the rotor  23 . 
     As shown in  FIG. 1 , the oil supply hole  59  is formed in communication with a rear-side oil supply path  59   a , and the rear-side oil supply path  59   b  is formed by branching from the rear-side oil supply path  59   a . The rear-side oil supply path  59   b  is in communication with the cylinder-side oil supply path  41 . 
     The rear-side bearing  63  is formed with the annular rear-side annular groove  73 , which is in communication with a rear-side communication path  65 . The rear-side communication path  65  is in communication with the rear-side annular groove  73  on its one-end side and opens to the high-pressure supply groove  69  on its other-end side. 
     The oil separator  21  is fixed to the rear-side block  31   b , the refrigerant having been compressed in the cylinder chamber  33  flows into the oil separator  21 , and the refrigerant and the oil O are separated from each other therein. 
     The drive shaft  27  is fixed to the rotor  23  on its one side and is rotatably supported by the bearings  47  and  63  of the respective side blocks  31   a  and  31   b . In addition, the motor section  4  is fixed to the other side of the drive shaft  27 . 
     The motor section  4  includes a stator  79  fixed to the inner wall  13  of the rear case  9  and a motor rotor  81  that is rotatably disposed on the inner periphery side of the stator  79  and rotates by a magnetic force. The motor rotor  81  transmits a rotational drive force to the compression section  3 , due to the rotation by the magnetic force. 
     Here, there will be described an interval between the first supply section  69   a  and the second supply section  69   b  of the high-pressure supply groove  69  in the rotation direction X of the rotor  23 . 
     In the present embodiment, as shown in  FIG. 3  and  FIG. 4 , the distance between the first supply section  69   a  and the second supply section  69   b  in the rotation direction X of the rotor  23  is set narrower than the width of the back pressure space  77  in the rotation direction X of the rotor  23 . 
     Here, as shown in  FIG. 5 , it is assumed that the interval between the first supply section  69   a  and the second supply section  69   b  of the high-pressure supply groove  69  in the rotation direction X of the rotor  23  is wider than the width of the back pressure space  77 .  FIG. 5  is an explanatory diagram showing a virtual example of a case where the first supply section and the second supply section of the high-pressure supply groove in  FIG. 3  are separately disposed at an interval at which the back pressure space of the vane groove does not communicate with any of them. 
       FIG. 6  is a graph showing changes in a pressure P 33   a  in the compression chamber  33   a , a pressure P 33   b  in the compression chamber  33   b  and a pressure P 77 B of the back pressure space  77 B, in accordance with a rotation angle of the rotor. As shown in  FIG. 6 , at an angle of 180 degrees, the back pressure space  77 B having completed communication with the intermediate-pressure supply groove  67  communicates with the high-pressure supply groove  69 . In the present embodiment, the high-pressure supply groove  69  is constituted by the first supply section  69   a  and the second supply section  69   b , and the back pressure space  77 B communicates with the first supply section  69   a  and thereafter communicates with the second supply section  69   b , along with rotation of the rotor  23  that rotates in the rotation direction X. 
     Since the interval between the first supply section  69   a  and the second supply section  69   b  of the high-pressure supply groove  69  in the rotation direction X of the rotor  23  is larger than the width of the back pressure space  77 B, there is generated a state where the back pressure space  77 B does not communicate with any of the first supply section  69   a  and the second supply section  69   b  when a communication destination of the back pressure space  77 B shifts from the first supply section  69   a  to the second supply section  69   b.    
     At this time, the vane  25 B stored in the vane groove  75 , the back pressure space  77 B of which is positioned between the first supply section  69   a  and the second supply section  69   b , receives force acting in a direction of intruding into the vane groove  75  from the inner peripheral surface  33   d  of the cylinder chamber  33  since the compression chambers  33   a  and  33   b  partitioned by the vane  25 B stay from the later stage of the compression process to the discharged process. Namely, when the back pressure space  77 B is positioned between the first supply section  69   a  and the second supply section  69   b , the volume of the back pressure space  77 B is in a state of being reduced. 
     However, since the back pressure space  77 B does not communicate with any of the first supply section  69   a  and the second supply section  69   b  at this position, it is not possible to release the high pressure of the amount corresponding to the reduced volume of the back pressure space  77 B to any place other than the back pressure space  77 B. Accordingly, in the middle stage of shifting the communication destination of the back pressure space  77 B from the first supply section  69   a  to the second supply section  69   b , the pressure in the back pressure space  77  temporarily rises as shown by P 1  in  FIG. 6 . Namely, since there is generated a state where the back pressure space  77 B is not in a communication state with any of the first supply section  69   a  and the second supply section  69   b , the pressure in the back pressure space  77  temporarily rises as shown by P 1  in  FIG. 6 . 
     When such a pressure rise in the back pressure space  77 B is generated, the vane  25 B which is receiving force of the direction of intruding into the vane groove  75  from the inner peripheral surface  33   d  of the cylinder chamber  33  attempts to project from the vane groove  75  by the risen pressure in the back pressure space  77 B. Then, there is a possibility that pressing force of the vane  25 B against the inner peripheral surface  33   d  of the cylinder chamber  33  may be increased more than necessary and the sliding resistance between the vane  25 B and the inner peripheral surface  33   d  of the cylinder chamber  33  may be increased. 
     The similar phenomenon to the above can be generated in a state where the vane  25 A and a vane  25 C are not in communication with any of the first supply section  69   a  and the second supply section  69   b.    
     Accordingly, in the gas compressor  1  of the present embodiment, as shown in  FIG. 7 , when the communication destination of the back pressure space  77  is shifted from the first supply section  69   a  to the second supply section  69   b , there is ensured, by a fixed amount or more, a cross-sectional area obtained by summing up a communication cross-sectional area Si between the back pressure space  77  and the first supply section  69   a  and a communication cross-sectional area S 3  between the back pressure space  77  and the second supply section  69   b.    
     Specifically, when the back pressure space  77  is in communication with the first supply section  69   a  and the second supply section  69   b , it is possible to release the high pressure in the back pressure space  77  to the high-pressure supply paths  71   a  and  71   b  through which the high pressure oil O is supplied to the first supply section  69   a  and the second supply section  69   b , and the rear-side communication path  65  continued to the high-pressure supply paths  71   a  and  71   b , the rear-side annular groove  73 , the rear-side oil supply path  59   a , and the oil supply hole  59 . 
     In order to ensure a high-pressure release route which is equal to or better than the above, in the gas compressor  1  of the present embodiment, an interval at which the total of the above-mentioned communication cross-sectional areas Si and S 3  becomes at least a minimum path cross-sectional area in a high-pressure oil O supply route for the first supply section  69   a  and the second supply section  69   b , from the high-pressure supply paths  71   a  and  71   b  down to the oil supply hole  59 , is provided between the first supply section  69   a  and the second supply section  69   b  in the rotation direction X of the rotor  23 . 
     Next, an operation of the gas compressor  1  according to the present embodiment will be described. 
     First, an electric current flows through a coil having been wound on the stator  79  of the motor section  4  by control of the inverter section  5  shown in  FIG. 1 . Magnetic force is generated by electric current flowing through the coil, and the motor rotor  81  disposed on the inner periphery of the stator  79  rotates. 
     The drive shaft  27  on the one-end side of which the motor rotor  81  is fixed rotates by rotation of the motor rotor  81 , and also the rotor  23  which is fixed on the other-end side of the drive shaft  27  rotates. 
     The refrigerant flows into the suction chamber  11  together with rotation of the rotor  23 , and the refrigerant is sucked into the cylinder chamber  33  from the suction chamber  11  via a suction slot (not shown) of the front-side block  31   a  (the suction process). The refrigerant having been sucked into the cylinder chamber  33  enters the compression chambers  33   a ,  33   b  and  33   c  formed in the cylinder chamber  33  by the plurality of vanes  25 , and thereby the refrigerant in the compression chambers  33   a ,  33   b  and  33   c  is compressed by rotation of the rotor  23  (the compression process). 
     The refrigerant having been compressed in the cylinder chamber  33  pushes the open/close valve  37  open, and is discharged from the discharge slot  35  (the discharged process) and is discharged from the discharge hole  61  into the discharge chamber  15  via the oil separator  21 . In addition, the refrigerant having been discharged from the discharge hole  61  is separated into the refrigerant and the oil O by the oil separator  21 , the refrigerant is discharged from a not shown discharge port to the not shown refrigerating cycle, and the oil O is stored under the discharge chamber  15 . 
     The oil having been stored under the discharge chamber  15  is supplied from the oil supply hole  59  in the rear-side block  31   b  to the rear-side bearing  63  through the rear-side oil supply path  59   a.    
     The high-pressure oil having been supplied to the rear-side bearing  63  is reduced to intermediate pressure higher than the pressure (the suction pressure) of the sucked refrigerant and lower than the pressure (the discharged pressure) of the discharged refrigerant, by being squeezed between the rear-side bearing  63  and the drive shaft  27 , and the oil O having been reduced to the intermediate pressure is supplied to the intermediate-pressure supply groove  67  through a gap between the drive shaft  27  and the rear-side block  31   b.    
     The intermediate pressure oil O having been supplied to the intermediate-pressure supply groove  67  supplies the intermediate pressure to the back pressure space  77  and supplies the intermediate pressure to the back surface of the vane  25  such that the vane  25  projects from the vane groove  75 , over a range from the refrigerant suction process to the compression process as shown in  FIG. 3 . 
     In addition, the high-pressure oil O having been supplied to the rear-side bearing  63  is supplied from the high-pressure supply paths  71   a  and  71   b  opening to the rear-side end surface  57  to the first supply section  69   a  and the second supply section  69   b  of the high-pressure supply groove  69 , via the rear-side communication path  65 . 
     The high-pressure oil O having been supplied to the first supply section  69   a  and the second supply section  69   b  supplies the high pressure to the back pressure space  77  and supplies the high pressure to the back surface of the vane  25  such that the vane  25  projects from the vane groove  75 , over a range from the refrigerant compression process to the discharged process as shown in  FIG. 3 . In addition, the first supply section  69   a  and the second supply section  69   b  communicate with the not shown respective corresponding supply sections of the high-pressure supply groove  53  on the front-side block  31   a  side via the back pressure space  77 , and the high pressure is also supplied from each of the supply sections of the high-pressure supply groove  53  to the back pressure space  77 . 
     Furthermore, the high-pressure oil O flows into the rear-side oil supply path  59   a  from the oil supply hole  59 , passes through the rear-side oil supply path  59   b  by being branched from the rear-side oil supply path  59   a , and is supplied from the front-side oil supply path  49  to the front-side bearing  47  via the cylinder-side oil supply path  41 . 
     The high-pressure oil O having been supplied to the front-side bearing  47  has intermediate pressure by being squeezed between the front-side bearing  47  and the drive shaft  27 , and the oil O having been reduced to the intermediate pressure is supplied to the intermediate-pressure supply groove  51  through the gap between the drive shaft  27  and the front-side block  31   a.    
     The high-pressure oil O having been supplied from the high-pressure supply grooves  53  and  69  of the front-side block  31   a  and the rear-side block  31   b  is supplied to the back pressure space  77  of the rotor  23  at a rotation latter-half position of the rotor  23  to impart the back pressure for making the vane  25  project from the vane groove  75 . 
     According to the gas compressor  1  of the present embodiment, the back pressure space  77  of the vane groove  75  having completed communication with the intermediate-pressure supply groove  67  communicates with the first supply section  69   a  of the high-pressure supply groove  69 , and the high pressure is supplied from the first supply section  69   a  thereto. 
     Thereafter, this back pressure space  77  completes communication with the first supply section  69   a  before the back pressure space  77  of the next vane groove  75  that is positioned on the upstream side of the rotation direction X communicates with the first supply section  69   a  and communicates with the second supply section  69   b  that is independent of the first supply section  69   a  and is positioned on the downstream side of the rotation direction X, and thus the high pressure is again supplied to the back pressure space. 
     Accordingly, at a time point when the back pressure space  77  having completed communication with the intermediate-pressure supply groove  67  communicates with the first supply section  69   a  of the high-pressure supply groove  69 , the preceding back pressure space  77  adjacent to the back pressure space  77  on the downstream side in the rotation direction X does not communicate with the first supply section  69   a  simultaneously. 
     In  FIG. 4 , there is shown a situation in which the back pressure space  77 A completes communication with the first supply section  69   a  before the back pressure space  77 B of the next vane groove  75  that is positioned on the upstream side in the rotation direction X communicates with the first supply section  69   a  and communicates with the second supply section  69   b  that is independent of the first supply section  69   a  and is positioned on the downstream side in the rotation direction X, and thus the high pressure is again supplied to the back pressure space  77 A. 
     Accordingly, the preceding back pressure space  77 A adjacent to the back pressure space  77 B on the downstream side in the rotation direction X does not communicate with the first supply section  69   a  simultaneously at a time point when the back pressure space  77 B communicates with the first supply section  69   a  of the high-pressure supply groove  69 . The similar relation is established not only between the back pressure space  77 A and the back pressure space  77 B, but also between the back pressure space  77 B and the back pressure space  77 C, and between the back pressure space  77 C and the backpressure space  77 A. 
     It is possible to prevent the pressure in the preceding back pressure space  77  from being temporarily lowered from the high pressure by the intermediate pressure before the following next back pressure space  77  rises to the high pressure, by allowing the two back pressure spaces  77  not to communicate with the first supply section  69   a  simultaneously. Accordingly, it is possible to prevent the occurrence of chattering in which the vane  25  repeats contact with and separation from the inner peripheral surface  33   d  of the cylinder chamber  33 , by a temporary reduction of pressure in the back pressure space  77  of the vane  25  in the early stage of the compression process. 
     Furthermore, the back pressure space  77  completes communication with the second supply section  69   b  before the back pressure space  77  of the next vane groove  75  which is positioned on the upstream side in the rotation direction X communicates with the second supply section  69   b . Accordingly, at a time point when the back pressure space  77  having completed communication with the first supply section  69   a  of the high-pressure supply groove  69  communicates with the second supply section  69   b  of the high-pressure supply groove  69 , the preceding back pressure space  77  adjacent to the downstream side of the back pressure space  77  in the rotation direction X does not communicate with the second supply section  69   b  simultaneously. 
       FIG. 8  is a graph showing changes in the pressure P 33   a  of the compression chamber  33   a , the pressure P 33   b  of the compression chamber  33   b  and the pressure P 77 B of the back pressure space  77 B in accordance with the rotation angle of the rotor. As shown in  FIG. 8 , at the angle of 180 degrees, the back pressure space  77 B having completed communication with the intermediate-pressure supply groove  67  communicates with the high-pressure supply groove  69 . In the present embodiment, the high-pressure supply groove  69  is constituted by the first supply section  69   a  and the second supply section  69   b  and the back pressure space  77 B communicates with the first supply section  69   a  and thereafter communicates with the second supply section  69   b , along with rotation of the rotor  23  that rotates in the rotation direction X. 
     As shown by P in the graph in  FIG. 17 , there occurred a phenomenon in which the pressure in the preceding back pressure space  107  is temporarily lowered from the high pressure, by a pressure which is in the middle of rising from the intermediate pressure of the following next back pressure space  107  to the high pressure. However, it is possible to prevent occurrence of the phenomenon as shown in the graph in  FIG. 8  by making the two back pressure spaces  77  not simultaneously communicate with the second supply section  69   b . Accordingly, it is possible to prevent the occurrence of chattering in which the vane  25  repeats contact with and separation from the inner peripheral surface  33   d  of the cylinder chamber  33  by a temporary reduction of pressure in the back pressure space  77  of the vane  25  in the later stage of the compression process and in the discharged process. 
     Furthermore, according to the gas compressor  1  of the present embodiment, the total of the communication cross-sectional areas Si and S 3  of the back pressure space  77  with the first supply section  69   a  and the second supply section  69   b  when the communication destination of the back pressure space  77  shifts from the first supply section  69   a  to the second supply section  69   b  is set to be a minimum path cross-sectional area or more of the supply route of the high-pressure oil O to the first supply section  69   a  and the second supply section  69   b.    
     In the middle stage of shifting the communication destination of the back pressure space  77  from the first supply section  69   a  to the second supply section  69   b , the back pressure space  77  communicates, in the minimum path cross-sectional area or more, with at least one of the first supply section  69   a  or the second supply section  69   b , and thus there can be ensured a destination to which the high pressure in the back pressure space  77  is released. 
     Accordingly, it is possible to prevent, as shown in the graph in  FIG. 8  by the above-mentioned configuration, such a phenomenon as indicated by P 1  in the graph in  FIG. 6 , namely, the phenomenon in which, in shifting the communication destination of the back pressure space  77  from the first supply section  69   a  to the second supply section  69   b , the pressure in the back pressure space  77  temporarily rises by a shortage of the cross-sectional area of a route along which the high pressure in the back pressure space  77  is released. 
     Thereby, there is prevented a phenomenon in which the pressing force of the vane  25  against the inner peripheral surface  33   d  of the cylinder chamber  33  is increased more than necessary by a temporary pressure increase in the back pressure space  77  and thus the sliding resistance between the both is increased. Therefore, it is possible to prevent increase in the sliding resistance of the vane  25  to the inner peripheral surface  33   d  of the cylinder chamber  33  due to increase in the power required for rotation of the rotor  23  by the temporary pressure increase in the back pressure space  77  in the later stage of the compression process and in the discharged process, thereby being able to maintain the operating performance as the gas compressor  1 . 
     Note that it is desirable that the second supply section  69   b  of the high-pressure supply groove  69  be formed into a shape of the largest possible size in the rotation direction X within a range in which the two back pressure spaces  77  mutually adjacent in the rotation direction X of the rotor  23  do not simultaneously communicate with each other. Consequently, it is possible to allow the back pressure space  77  in which pressure has been increased from the intermediate pressure toward the high pressure due to communication with the first supply section  69   a  to communicate with the second supply section  69   b  from an earlier stage of the compression process of the compression chambers  33   a ,  33   b  and  33   c , and thereafter to stabilize the pressure in the back pressure space  77  to the high pressure. 
     Accordingly, it is possible to start the discharged process of the compression chambers  33   a ,  33   b  and  33   c  at an earlier stage, the open/close valve  37  of the discharge slot  35  is opened at an earlier stage and the high-pressure refrigerant in the compression chambers  33   a ,  33   b  and  33   c  is efficiently and sufficiently discharged, and thereby it is possible to achieve enhancement of refrigerant compression efficiency. 
     In the present embodiment, it was assumed that the high-pressure supply groove  69  is divided into the two mutually independent first supply section  69   a  and second supply section  69   b  in the rotation direction X. However, the present invention is applicable also in a case where the high-pressure supply groove  69  is divided into three or more supply sections in the rotation direction X. In that case, the relation of the present invention is applied to the communication cross-sectional area of an upstream-side supply section or a downstream-side supply section with the back pressure space  77  when the back pressure space  77  moves striding over the two adjacent supply sections in the rotation direction X. 
     Second Embodiment 
     Next, the second embodiment of the present invention will be described with reference to  FIG. 9  to  FIG. 15 . 
       FIG. 9  and  FIG. 10  show a structure of a vane rotary-type gas compressor according to the second embodiment. The gas compressor of the second embodiment has a rear-side block  31   b   2  different from the rear-side block  31   b  of the first embodiment. Configurations other than the rear-side block  31   b   2  are the configurations that are similar to those of the first embodiment. The same symbols are attached to the same constituent points as those in the first embodiment, a description thereof is omitted and only different configurations will be described. 
     In the present embodiment, an interval  69   c  having a size that is not less than that of the back pressure space  77  of the vane groove  75  is provided between the first supply section  69   a  and the second supply section  69   b  in the rotation direction X of the rotor  23 . Namely, the interval  69   c  provided between the first supply section  69   a  and the second supply section  69   b  is set larger than the width of the back pressure space  77  of the vane groove  75 . 
     In a state shown in  FIG. 11 , the back pressure space  77 B of the vane groove  75  in the vane  25 B which partitions the compression chamber  33   b  having moved from the suction process to the compression process by rotation of the rotor  23  and the compression chamber  33   a  which is positioned on the downstream side of the compression chamber  33   b  in the rotation direction X of the rotor  23  and which has moved from the compression process to the discharged process communicates with the first supply section  69   a  of the high-pressure supply groove  69 . 
     In this state, the back pressure space  77 A of the vane groove  75  in the vane  25 A that precedes the vane  25 B in the downstream side of the vane  25 B in the rotation direction X of the rotor  23  has already completed communication with the second supply section  69   b  and starts to communicate with the intermediate-pressure supply section  67  that is positioned on the downstream side of the rotation direction X. 
     Here, there will be described the position of the interval  69   c  between the first supply section  69   a  and the second supply section  69   b  of the high-pressure supply groove  69  in the rotation direction X of the rotor  23 . When the rotor  23  rotates in the rotation direction X after the state shown in  FIG. 11 , the back pressure space  77 B completes communication with the first supply section  69   a  and the back pressure space  77 B communicates with the interval  69   c  provided between the first supply section  69   a  and the second supply section  69   b . At this time, there is generated a state where the back pressure space  77 B is not in communication with any of the first supply section  69   a  and the second supply section  69   b.    
     In this state, when the projection stroke of the vane  25 B relative to the vane groove  75  is reduced along with rotation of the rotor  23  in the rotation direction X, the volume of the back pressure space  77 B is reduced. At this time, since the back pressure space  77 B is not in communication with any of the first supply section  69   a  and the second supply section  69   b , it is not possible to release the high pressure of the amount corresponding to the reduced volume to them. 
     Accordingly, there is assumed a case where, when the vane  25 B is in sliding contact with a region indicated by a range (A) in  FIG. 12  on the inner peripheral surface  33   d  of the cylinder chamber  33 , namely, the region in which the projection stroke of the vane  25 B relative to the vane groove  75  is reduced at a rate equal to or more than a constant level along with rotation of the rotor  23  in the rotation direction X, the interval  69   c  is disposed at a position whit which the back pressure space  77 B communicates. 
       FIG. 12  is an explanatory diagram showing a positional relation between the region in which the projection stroke of the vane  25 B relative to the vane groove  75  is reduced at a rate equal to or more than a constant level and the interval  69   c.    
     In this case, the volume of the back pressure space  77 B is reduced at a rate in accordance with a reduction rate of the projection stroke of the vane  25 B in a state where the back pressure space  77 B is isolated from the first supply section  69   a  and the second supply section  69   b , and the pressure in the back pressure space  77 B temporarily rises as indicated by P 1  in  FIG. 13 . 
     In a case where such a pressure rise of the back pressure space  77 B is generated, the vane  25 B which receives force acting in a direction of intruding into the vane groove  75  from the inner peripheral surface  33   d  of the cylinder chamber  33  attempts to project from the vane groove  75  by the risen pressure in the back pressure space  77 B. Then, there is a possibility that the pressing force of the vane  25 B against the inner peripheral surface  33   d  of the cylinder chamber  33  may be increased more than necessary and the sliding resistance between the vane  25 B and the inner peripheral surface  33   d  of the cylinder chamber  33  may be increased. 
     Accordingly, it is configured such that a region in which the reduction rate of the projection stroke of the vane  25  relative to the vane groove  75  along with rotation of the rotor  23  in the rotation direction X on the inner peripheral surface  33   d  of the cylinder chamber  33  becomes a reduction rate not more than a predetermined threshold value which is lower than the above-mentioned constant rate is set as a region in which the reduction rate of the projection stroke is small, and the interval  69   c  is disposed so that the back pressure space  77  communicates with the interval  69   c  when the vane  25  comes into sliding contact with the region in which the reduction rate of the projection stroke concerned is small in the gas compressor  1  of the present embodiment. 
     Specifically, in the present embodiment, the inner peripheral surface  33   d  of the cylinder chamber  33  is, as shown in  FIG. 14 , formed so that four regions of: 
     (a) a region in which the projection stroke of the vane  25  that is in sliding contact with the inner peripheral surface  33   d  of the cylinder chamber  33  from the vane groove  75  is increased along with rotation of the rotor  23  in the rotation direction X; 
     (b) a region in which the projection stroke of the vane  25  that is in sliding contact with the inner peripheral surface  33   d  of the cylinder chamber  33  from the vane groove  75  is decreased along with rotation of the rotor  23  in the rotation direction X; 
     (c) a region in which the projection stroke of the vane  25  that is in sliding contact with the inner peripheral surface  33   d  of the cylinder chamber  33  from the vane groove  75  is decreased along with rotation of the rotor  23  in the rotation direction X and in which a reduction rate thereof is smaller than that in the region in (b); and 
     (d) a region in which the projection stroke of the vane  25  that is in sliding contact with the inner peripheral surface  33   d  of the cylinder chamber  33  from the vane groove  75  is decreased along with rotation of the rotor  23  in the rotation direction X and in which a reduction rate thereof is larger than that in the region in (c) and is smaller than that in the region in (b) 
     are sequentially successive in the rotation direction X of the rotor  23 . 
     Accordingly, the interval  69   c  is disposed at a position where the back pressure space  77  communicates with the interval when the vane  25  is in sliding contact with the region (c) in which the reduction rate of the projection stroke of the vane  25  along with rotation of the rotor  23  in the rotation direction X is the smallest. 
     Next, an operation of the gas compressor  1  according to the present embodiment will be described. 
     Also in the present embodiment, at a time point when the back pressure space  77  having completed communication with the intermediate-pressure supply groove  67  communicates with the first supply section  69   a  of the high-pressure supply groove  69 , the preceding back pressure space  77  adjacent to the back pressure space  77  on the downstream side in the rotation direction X does not communicate with the first supply section  69   a  simultaneously. 
     Accordingly, at a time point when the back pressure space  77  having completed communication with the intermediate-pressure supply groove  67  communicates with the first supply section  69   a  of the high-pressure supply groove  69 , the preceding back pressure space  77  adjacent to the back pressure space  77  on the downstream side in the rotation direction X does not communicate with the first supply section  69   a  simultaneously. 
     It is possible to prevent the pressure in the preceding back pressure space  77  from being temporarily lowered from the high pressure by the intermediate pressure before the following next back pressure space  77  rises to the high pressure, by allowing the two back pressure spaces  77  not to communicate with the first supply section  69   a  simultaneously. Accordingly, it is possible to prevent the occurrence of chattering in which the vane  25  repeats contact with and separation from the inner peripheral surface  33   d  of the cylinder chamber  33 , by a temporary reduction of pressure in the back pressure space  77  of the vane  25  in the early stage of the compression process. 
     Furthermore, the back pressure space  77  completes communication with the second supply section  69   b  before the back pressure space  77  of the next vane groove  75  which is positioned on the upstream side in the rotation direction X communicates with the second supply section  69   b . Accordingly, at a time point when the back pressure space  77  having completed communication with the first supply section  69   a  of the high-pressure supply groove  69  communicates with the second supply section  69   b  of the high-pressure supply groove  69 , the preceding back pressure space  77  adjacent to the downstream side of the back pressure space  77  in the rotation direction X does not communicate with the second supply section  69   b  simultaneously. 
     Accordingly, as shown in the graph in  FIG. 15 , it is possible to prevent the occurrence of chattering in which the vane  25  repeats contact with and separation from the inner peripheral surface  33   d  of the cylinder chamber  33  by a temporary reduction of pressure in the back pressure space  77  of the vane  25  in the later stage of the compression process and in the discharged process. 
     Furthermore, according to the gas compressor  1  of the present embodiment, the interval  69   c  between the first supply section  69   a  and the second supply section  69   b  is positioned such that, when the back pressure space  77  communicates with the interval  69   c  between the first supply section  69   a  and the second supply section  69   b , the vane  25  stored in the vane groove  75  of the back pressure space  77  comes into sliding contact with the region (c) in which the reduction rate of the projection stroke of the vane  25  along with rotation of the rotor  23  in the rotation direction X is the smallest. 
     Accordingly, when the back pressure space  77  communicates with the interval  69   c  between the first supply section  69   a  and the second supply section  69   b , the projection stroke of the vane  25  is hardly reduced as shown by a part surrounded by a round frame in  FIG. 15  and also the volume of the back pressure space  77  is hardly reduced. Therefore, as shown in  FIG. 15 , a temporary pressure increase in the back pressure space  77  is not generated when the back pressure space  77  communicates with the interval  69   c.    
     Consequently, as indicated by P 1  in the graph in  FIG. 13 , when the communication destination of the back pressure space  77  becomes the interval  69   c  between the first supply section  69   a  and the second supply section  69   b , it is possible to prevent, as shown in the graph in  FIG. 15 , a phenomenon in which the releasing route for the high pressure in the back pressure space  77  is eliminated and the pressure in the back pressure space  77  temporarily rises. 
     Thereby, there is prevented a phenomenon in which the pressing force of the vane  25  against the inner peripheral surface  33   d  of the cylinder chamber  33  is increased more than necessary by a temporary pressure increase in the back pressure space  77  and thus the sliding resistance between the both is increased. Therefore, it is possible to prevent increase in the sliding resistance of the vane  25  to the inner peripheral surface  33   d  of the cylinder chamber  33  due to increase in the power required for rotation of the rotor  23  by the temporary pressure increase in the back pressure space  77  in the later stage of the compression process and in the discharged process, thereby being able to maintain the operating performance as the gas compressor  1 . 
     Note that it is desirable that the second supply section  69   b  of the high-pressure supply groove  69  be formed into a shape of the largest possible size in the rotation direction X within a range in which the two back pressure spaces  77  mutually adjacent in the rotation direction X of the rotor  23  do not simultaneously communicate with each other. Consequently, it is possible to allow the back pressure space  77  in which pressure has been increased from the intermediate pressure toward the high pressure due to communication with the first supply section  69   a  to communicate with the second supply section  69   b  from an earlier stage of the compression process of the compression chambers  33   a ,  33   b  and  33   c , and thereafter to stabilize the pressure in the back pressure space  77  to the high pressure. 
     Accordingly, it is possible to start the discharged process of the compression chambers  33   a ,  33   b  and  33   c  at an earlier stage, the open/close valve  37  of the discharge slot  35  is opened at an earlier stage and the high-pressure refrigerant in the compression chambers  33   a ,  33   b  and  33   c  is efficiently and sufficiently discharged, and thereby it is possible to achieve enhancement of refrigerant compression efficiency. 
     Note that, although, in the present embodiment, the interval  69   c  provided between the first supply section  69   a  and the second supply section  69   b  is set larger than the width of the back pressure space  77  of the vane groove  75 , the interval  69   c  may have a size smaller than that of the back pressure space  77  in the rotation direction X of the rotor  23 . In this case, when the back pressure space  77  strides over the interval  69   c  in shifting the communication destination of the back pressure space  77  from the first supply section  69   a  to the second supply section  69   b  of the high-pressure supply section  69 , the communication cross-sectional area of the back pressure space  77  for each of the supply sections  69   a  and  69   b  is reduced by an amount of overlapping the interval  69   c.    
     Since the communication cross-sectional area is reduced, when the vane  25  intrudes into the back pressure space  77  side of the vane groove  75  along with rotation of the rotor  23  and the volume of the back pressure space  77  is reduced, efficiency of releasing the high pressure in the back pressure space  77  to the first supply section  69   a  and the second supply section  69   b  is reduced by the amount of the reduced volume. Then, there is a possibility that the pressure in the back pressure space  77  may temporarily rise in the later stage of the compression process and in the discharged process, the pressing force of the vane  25  against the inner peripheral surface  33   d  of the cylinder chamber  33  may be increased more than necessary and the sliding resistance between the vane  25  and the inner peripheral surface  33   d  of the cylinder chamber  33  may be increased. 
     However, the interval  69   c  is disposed at a position where the back pressure space  77  communicates with the interval  69   c  when the vane  25  is in sliding contact with the region (c) in which the reduction rate of the projection stroke of the vane  25  along with rotation of the rotor  23  in the rotation direction X is the smallest. Therefore, there can be prevented a temporary rise in the pressure in the back pressure space  77  by reduction in the releasing efficiency of the high pressure in the back pressure space  77 . Accordingly, it is possible to prevent a phenomenon in which the sliding resistance of the vane  25  to the inner peripheral surface  33   d  of the cylinder chamber  33  is increased by the temporary pressure increase in the back pressure space  77  in the later stage of the compression process and in the discharged process and thus the power required for rotation of the rotor  23  is increased, thereby being able to maintain the operating performance as the gas compressor  1 . 
     Note that, in the present embodiment, a region of the inner peripheral surface  33   d  of the cylinder chamber  33  with which the vane  25  comes into sliding contact when the back pressure space  77  communicates with the interval  69   c  was determined by the use of the reduction rate of the projection stroke of the vane  25  to the vane groove  75  as a standard. In the determination, an upper limit value of an allowable range of the reduction rate of the projection stroke of the vane  25  to the vane groove  75  is determined in accordance with an allowable range for a temporary increase in pressure in the back pressure space  77 . 
     Then, the determined upper limit value is set as a predetermined threshold value, and there is determined a region in which the reduction rate of the projection stroke of the vane  25  on the inner peripheral surface  33   d  of the cylinder chamber  33  becomes not more than this threshold value. The interval  69   c  may be disposed such that, when the vane  25  comes into sliding contact with the thus determined region on the inner peripheral surface  33   d  of the cylinder chamber  33 , the back pressure space  77  communicates with the interval  69   c.    
     By making the determination in this way, it is possible to maintain the temporary pressure increase of the back pressure space  77  by a reduction in projection stroke of the vane  25  within the allowable range during a period when the back pressure space  77  is in communication with the interval  69   c  between the first supply section  69   a  and the second supply section  69   b . Accordingly, it is possible to prevent increase in the sliding resistance of the vane  25  to the inner peripheral surface  33   d  of the cylinder chamber  33  due to increase in the power required for rotation of the rotor  23  by the temporary pressure increase in the back pressure space  77  in the later stage of the compression process and in the discharged process, thereby being able to maintain the operating performance as the gas compressor  1 . 
     In the present embodiment, it has been made such that the high-pressure supply groove  69  is divided into the two mutually independent first supply section  69   a  and second supply section  69   b  in the rotation direction X. However, the present invention is applicable also in a case where the high-pressure supply groove  69  is divided into three or more supply sections in the rotation direction X. In that case, the relation of the present invention is applied to a relative position of the interval between the two supply sections adjacent to each other in the rotation direction X and the inner peripheral surface of the cylinder chamber. 
     Other Embodiments 
     In the above-mentioned plurality of embodiments, the second supply section  69   b  of the high-pressure supply groove  69  was set to have a size at which the two back pressure spaces  77  adjacent to each other in the rotation direction X of the rotor  23  do not communicate with each other simultaneously. For example, the second supply section  69   b  may have a space of a size larger than the size of the first supply section  69   a  in the rotation direction X. Consequently, it is possible to allow the back pressure space  77  in which pressure has been increased from the intermediate pressure toward the high pressure due to communication with the first supply section  69   a  to communicate with the second supply section  69   b  from an earlier stage of the compression process of the compression chambers  33   a ,  33   b  and  33   c , and thereafter to stabilize the pressure in the back pressure space  77  to the high pressure. 
     Accordingly, it is possible to start the discharged process of the compression chambers  33   a ,  33   b  and  33   c  at an earlier stage, the open/close valve  37  of the discharge slot  35  is opened at an earlier stage and the high-pressure refrigerant in the compression chambers  33   a ,  33   b  and  33   c  is efficiently and sufficiently discharged, and thereby it is possible to achieve enhancement of refrigerant compression efficiency. 
     In addition, in the above-mentioned plurality of embodiments, a description has been made by taking, by way of example, a case of dividing the high-pressure supply groove  69  into two of the first supply section  69   a  and the second supply section  69   b  in the rotation direction X in order to prevent the back pressure space  77  of the vane  25  from communicating with the same supply section as that of the back pressure space  77  of the upstream-side vane  25  by way of example. However, the present invention is also widely applicable to a case where the high-pressure supply groove  69  is divided into three or more supply sections in the rotation direction X. 
     In that case, it is possible to obtain the similar effects to those of the above-mentioned plurality of embodiments by forming, among the three or more supply sections, one supply section that communicates with the back pressure space  77  that is in a state where the pressure in the back pressure space  77  is in the middle of rising from the intermediate pressure to the high pressure, into a shape in which the two back pressure spaces  77  adjacent to each other in the rotation direction X do not communicate with each other simultaneously. 
     Namely, the supply section positioned second from the most upstream side of the rotation direction X becomes at least an object to be formed into a shape in which the two back pressure spaces  77  adjacent to each other in the rotation direction X do not communicate with each other simultaneously. In addition, also each of the third and subsequent supply sections from the most upstream side becomes the object to be formed into a shape in which the two back pressure spaces  77  adjacent to each other in the rotation direction X do not communicate with each other simultaneously, in a case of communicating with the back pressure space  77  when the pressure of the back pressure space  77  is in the middle of rising from the intermediate pressure to the high pressure. 
     The above embodiments of the present invention are merely illustrative ones which have been described for facilitating understanding of the present invention and the present invention is not limited to the embodiments concerned. The technical scope of the present invention includes, not limited to specific technical matters disclosed in the above-mentioned embodiments, various modifications, changes, alternative technologies and the like, which can be easily derived therefrom. 
     The present application claims the priority based on Japanese Patent Application No. 2014-260491 filed on Dec. 24, 2014, based on Japanese Patent Application No. 2014-260492 filed on Dec. 24, 2014 and based on Japanese Patent Application No. 2014-260500 filed on Dec. 24, 2014, the entire contents of which are incorporated herein by reference. 
     INDUSTRIAL APPLICABILITY 
     According to the present invention, the back pressure space of the vane groove having completed communication with the intermediate-pressure supply section communicates with the first supply section of the high-pressure supply section until the refrigerant pressure in each of the compression chambers having been partitioned by the vane stored in the vane groove reaches the highest pressure, and then the high pressure is supplied from the first supply section. Thereafter, this back pressure space completes communication with the first supply section before the back pressure space of the next vane groove on the upstream side of the rotation direction communicates with the first supply section, and then communicates with the next second supply section that is independent of the first supply section and subsequently the high pressure is again supplied thereto. 
     Accordingly, at a time point when the back pressure space having completed communication with the intermediate-pressure supply section communicates with the first supply section of the high-pressure supply section, the preceding back pressure space which is adjacent to the back pressure space on the downstream side in the rotation direction does not communicate with the first supply section simultaneously. Consequently, the pressure in the preceding back pressure space is prevented from being temporarily lowered from the high pressure by the intermediate pressure of the following next back pressure space and the occurrence of chattering of the vane by a temporary reduction in pressure in the back pressure space of the vane can be prevented. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  gas compressor 
               2  housing 
               3  compression section 
               4  motor section 
               5  inverter section 
               7  front head 
               9  rear case 
               11  suction chamber 
               13  inner wall 
               15 ,  108  discharge chamber 
               19  compression block 
               21  oil separator 
               23 ,  102  rotor 
               23   a  outer peripheral surface 
               25  ( 25 A,  25 B,  25 C),  103  vane 
               27  drive shaft 
               29 ,  100  cylinder block 
               31 ,  101  side block 
               31   a  front-side block 
               31   b  rear-side block 
               33 ,  105  cylinder chamber 
               33   a ,  33   b ,  33   c ,  105   a ,  105   b ,  105   c  compression chamber 
               33   d  inner peripheral surface 
               35  discharge slot 
               37 ,  109  open/close valve 
               39  suction slot 
               41  cylinder-side oil supply path 
               43  front-side end surface 
               47  front-side bearing 
               49  front-side oil supply path 
               51 ,  113  intermediate-pressure supply groove 
               53 ,  114  high-pressure supply groove 
               55  front-side annular groove 
               57  rear-side end surface 
               59  oil supply hole 
               59   a  rear-side oil supply path 
               59   b  rear-side oil supply path 
               61  discharge hole 
               63  rear-side bearing 
               65  rear-side communication path 
               67  intermediate-pressure supply groove (intermediate-pressure supply section) 
               69  high-pressure supply groove (high-pressure supply section) 
               69   a  first supply section (upstream-side supply section) 
               69   b  second supply section (downstream-side supply section) 
               69   c  interval 
               71   a ,  71   b  high-pressure supply path 
               73  rear-side annular groove 
               75 ,  106  vane groove 
               77  ( 77 A,  77 B,  77 C),  107  back pressure space 
               79  stator 
               81  motor rotor 
               110  suction port 
             O oil 
             X rotation direction