Patent Publication Number: US-6981390-B2

Title: Refrigerant cycle system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is related to and claims priority from Japanese Patent Applications No. 2002-315799 filed on Oct. 30, 2002, No. 2003-27049 filed on Feb. 4, 2003 and No. 2003-39924 filed on Feb. 18, 2003, the contents of which are hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a refrigerant cycle system for a vehicle air conditioner and the like. More particularly, the present invention relates to a separator-integrated condenser including first and second heat-exchanging portions and a gas-liquid separator. 
   2. Description of Related Art 
   For example, in a refrigerant cycle system disclosed in U.S. Pat. No. 6,427,480 (corresponding to JP-A-2002-323274), a condenser  302  includes first and second heat-exchanging portions  305 ,  306  and a gas-liquid separator  307  disposed between the first and second heat-exchanging portions  305 ,  306 , as shown in  FIG. 19 . A main part of gas refrigerant discharged from a compressor  301  is introduced into the first heat-exchanging portion  305 , and is condensed therein. A part of refrigerant (liquid refrigerant), condensed in the first heat-exchanging portion  305 , flows into the gas-liquid separator  307  through a liquid-refrigerant bypass passage  309 . At this time, a part of gas refrigerant, discharged from the compressor  301 , is distributed into a gas-refrigerant bypass passage  310  having a gas refrigerant throttle  310   a , and flows into the gas-liquid separator  307  through the gas-refrigerant bypass passage  310 . In the gas-liquid separator  307 , the condensed refrigerant (liquid refrigerant) from the liquid refrigerant bypass passage  309  and the discharged gas refrigerant from the gas-refrigerant bypass passage  310  are mixed and heat-exchanged with each other. Then, the mixed refrigerant is separated in the gas-liquid separator  307  into gas refrigerant and liquid refrigerant due to a mass density difference therebetween. Thus, the liquid refrigerant is stored at a lower side in the gas-liquid separator  307 , and the gas refrigerant is stored at an upper side in the gas-liquid separator  307 . 
   The second heat-exchanging portion  306  is disposed downstream of the first heat-exchanging portion  305 . Specifically, a liquid-refrigerant introduction passage  311 , through which a main part of liquid refrigerant condensed in the first heat-exchanging portion  305  flows, is connected to an inlet side of the second heat-exchanging portion  306 . Further, a gas-refrigerant return passage  312  and a liquid-refrigerant return passage  313  are connected to the inlet side of the second heat-exchanging portion  306 . In this way, the main part of liquid refrigerant condensed in the first heat-exchanging portion  305 , the gas refrigerant stored at the upper side in the gas-liquid separator  307  and the liquid refrigerant stored at the lower side in the gas-liquid separator  307  are introduced into the second heat-exchanging portion  306 . Then, they are super-cooled in the second heat-exchanging portion  306 . The super-cooled refrigerant is decompressed by a decompression device  303  to be low-pressure gas-liquid refrigerant. The low-pressure refrigerant from the decompression device  303  is evaporated in an evaporator  304 , and the evaporated refrigerant is sucked into the compressor  301 . 
   The refrigerant cycle system was studied by the present inventors, and the following problem has been found. That is, a refrigerant flow amount in the refrigerant cycle is required to be adjusted at a predetermined target flow amount in accordance with a super-heating degree of gas refrigerant discharged from the compressor  301 . Therefore, a refrigerant passage such as the gas-refrigerant bypass passage  310  having the gas refrigerant throttle  310   a  is required to be designed finely, and the condenser  302  and the gas-liquid separator  307  are also required to be formed finely in each dimension. Specifically, in the above refrigerant cycle system, apart of refrigerant (liquid refrigerant) condensed in the first heat-exchanging portion  305  flows into the gas-liquid separator  307  through the liquid-refrigerant bypass passage  309 . At this time, a part of gas refrigerant discharged from the compressor  301  also flows into the gas-liquid separator  307  through the gas-refrigerant bypass passage  310 . Here, a flow amount ratio between gas refrigerant and liquid refrigerant flowing into the gas-liquid separator  307  is experimentally set at a predetermined ratio so that a super-heating degree of the discharged gas refrigerant from the compressor  301  is suitably fed back into the gas-liquid separator  307 . For example, a mass flow ratio of the liquid refrigerant to the discharged gas refrigerant flowing into the gas-liquid separator  307  is set at a ratio of 1:2. 
   In this way, since only a part of liquid refrigerant condensed in the first heat-exchanging portion  305  is circulated into the gas-liquid separator  307 , only a small amount of liquid refrigerant flows into the gas-liquid separator  307 . Further, the discharged gas refrigerant from the compressor  301  is circulated into the gas-liquid separator  307  by a predetermined ratio relative to the small amount of liquid refrigerant flowing thereinto. Therefore, an amount of the discharged gas refrigerant flowing from the compressor  301  into the gas-liquid separator  307  is also small. As a result, a passage diameter of the gas refrigerant throttle  310   a  of the gas-refrigerant bypass passage  310  is required to be designed at a very small dimension (e.g., Ø2.5 mm). 
   On the other hand, the passage diameter of the gas refrigerant throttle  310   a  generally varies from the design diameter, due to dimension variations of the passage diameter in the manufacturing process, a solder intrusion into the gas refrigerant throttle  310   a  in brazing of the condenser  302  and the like. Further, since the passage diameter of the gas refrigerant throttle  310   a  is designed at a very small dimension, an amount of the discharged gas refrigerant flowing from the compressor  301  into the gas-liquid separator  307  varies largely when the passage diameter of the gas refrigerant throttle  310   a  varies in the manufacturing process. 
   That is, in this case, the flow ratio of the discharged gas refrigerant flowing into the gas-liquid separator  307  to the liquid refrigerant flowing into the gas-liquid separator  307  varies largely. As a result, the flow amount of refrigerant circulated in the refrigerant cycle cannot be adjusted in accordance with the super-heating degree of the discharged gas refrigerant. For example, when the passage diameter of the gas refrigerant throttle  310   a  reduces from the design diameter due to solder intrusion and the like, the flow ratio of the discharged gas refrigerant flowing into the gas-liquid separator  307  to the liquid refrigerant flowing into the gas-liquid separator  307  is reduced. Therefore, the super-heating degree information of the gas refrigerant discharged from the compressor  301  cannot be suitably fed back into the gas-liquid separator  307 , thereby extremely increasing an amount of liquid refrigerant stored in the gas-liquid separator  307 . As a result, the flow amount of refrigerant circulated in the refrigerant cycle system extremely reduces relative to the super-heating degree of the discharged gas refrigerant, thereby reducing cooling performance of the refrigerant cycle system. 
   SUMMARY OF THE INVENTION 
   In view of the above problems, it is an object of the present invention to provide a refrigerant cycle system capable of adjusting a flow amount of refrigerant circulated in a refrigerant cycle by adjusting an amount of liquid refrigerant stored in the gas-liquid separator. In the refrigerant cycle system, dimension variations in manufacturing are not greatly affected to an adjustment operation of the liquid refrigerant in the gas-liquid separator. 
   It is another object of the present invention to simplify a refrigerant passage structure of a condenser in the refrigerant cycle system. 
   According to an aspect of the present invention, a refrigerant cycle system includes a first heat-exchanging portion for cooling and condensing gas refrigerant discharged from a compressor by radiating heat, a gas-liquid separator into which all of refrigerant after passing through the first heat-exchanging portion and a part of gas refrigerant discharged from the compressor are introduced, a second heat-exchanging portion disposed downstream of the first heat-exchanging portion for cooling and condensing refrigerant flowing from the gas-liquid separator by radiating heat, a gas-refrigerant return passage through which at least gas refrigerant in the gas-liquid separator is introduced into the second heat-exchanging portion, a decompression device disposed downstream of the second heat-exchanging portion for decompressing refrigerant after passing through the second heat-exchanging portion, and an evaporator disposed downstream of the decompression device for evaporating refrigerant flowing out of the decompression device. Since all of condensed refrigerant (liquid refrigerant) after passing through the first heat-exchanging portion is introduced into the gas-liquid separator, an amount of liquid refrigerant introduced into the gas-liquid separator can be increased. Therefore, an amount of gas refrigerant introduced into the gas-liquid separator can be also increased. As a result, a passage diameter of a gas-refrigerant bypass passage for regulating the gas-refrigerant introduction amount flowing into the gas-liquid separator can be effectively increased. Accordingly, even the passage diameter varies in manufacturing of the condenser, the variation ratio of the gas refrigerant amount introduced into the gas-liquid separator to the liquid refrigerant amount introduced thereinto, due to the passage diameter variation, can be effectively reduced. As a result, the adjusting operation of the liquid refrigerant amount in the gas-liquid separator is not greatly affected by the dimension variations of the gas-refrigerant bypass passage in the manufacturing. Therefore, even if dimension variations are generated in some degree, a refrigerant amount circulated in the refrigerant cycle system can be suitably adjusted in accordance with the super-heating degree of the gas refrigerant discharged from the compressor. In this case, the condenser and the gas-liquid separator are not required to be finely produced, thereby reducing production cost. 
   Preferably, refrigerant cycle system is provided with a gas-liquid mixing portion in which all of refrigerant after passing through the first heat-exchanging portion and a part of gas refrigerant discharged from the compressor are introduced and mixed. In this case, the gas-liquid separator has a refrigerant inlet from which refrigerant is introduced, and the gas-liquid mixing portion is connected to the refrigerant inlet of the gas-liquid separator. Specifically, first and second heat-exchanging portions are integrated to form a heat exchanging section, a first header tank and a second header tank of a condenser, the heat exchanging section includes a plurality of tubes through which refrigerant flows, the first header tank and the second header tank are disposed at two sides of the heat exchanging section to communicate with the tubes, and the gas-liquid mixing portion is provided in the first header tank. 
   Preferably, a passage-area adjusting device is disposed in the gas-refrigerant bypass passage for adjusting a passage area of the gas-refrigerant bypass passage. Accordingly, the passage area of the gas-refrigerant bypass passage can be suitably adjusted by the passage-area adjusting device in accordance with an actual pressure loss in the refrigerant passage of the first heat-exchanging portion. 
   In the present invention, an inlet portion, from which gas refrigerant discharged from the compressor is introduced into the first heat-exchanging portion, can be provided in the first heat-exchanging portion. In this case, the gas-refrigerant bypass passage and the passage-area adjusting device are provided in the first heat-exchanging portion. Alternatively, the inlet portion is provided in the gas-liquid separator, and the gas-refrigerant bypass passage and the passage-area adjusting device are provided in the gas-liquid separator. 
   For example, when the inlet portion is disposed outside the first heat-exchanging portion, a gas-refrigerant condensing passage through which the gas refrigerant discharged from the compressor is introduced from the inlet portion into the first heat-exchanging portion is disposed outside the first heat-exchanging portion, and a gas-refrigerant bypass passage through which the gas refrigerant discharged from the compressor is directly introduced into the gas-liquid separator while bypassing the first heat-exchanging portion, is also disposed outside the first heat-exchanging portion. Accordingly, a gas-refrigerant distribution passage (the inlet portion, the gas-refrigerant condensing passage and the gas-refrigerant bypass passage) is not required to be arranged in the first heat-exchanging portion, thereby simplifying the refrigerant passage structure of the condenser, and reducing the production cost of the condenser. 
   According to an another aspect of the present invention, a refrigerant cycle system includes a first heat-exchanging portion for cooling and condensing gas refrigerant discharged from the compressor by radiating heat, a gas-liquid separator into which all of refrigerant after passing through the first heat-exchanging portion is introduced, a second heat-exchanging portion disposed downstream of the first heat-exchanging portion for cooling and condensing refrigerant flowing from the gas-liquid separator by radiating heat, and a heating unit for adjusting a heating amount of the liquid refrigerant in the gas-liquid separator in accordance with any one of a super-heating degree of gas refrigerant discharged from the compressor and a super-heating degree of gas refrigerant at an outlet of the evaporator. Because all of the condensed refrigerant from the first heat-exchanging portion is introduced into the gas-liquid separator, the heating amount of the liquid refrigerant in the gas-liquid separator can be set relatively large. Therefore, the heating of the liquid refrigerant in the gas-liquid separator can be readily accurately performed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Additional objects and advantages of the present invention will be more readily apparent from the following detailed description of preferred embodiments when taken together with the accompanying drawings, in which: 
       FIG. 1  is a schematic diagram showing a refrigerant cycle system according to a first embodiment of the present invention; 
       FIG. 2  is a schematic sectional view showing a disassembled state of a separator-integrated condenser with a gas-liquid separator according to the first embodiment; 
       FIG. 3  is a schematic sectional view showing a refrigerant inlet portion of the gas-liquid separator in the separator-integrated condenser according to the first embodiment; 
       FIG. 4A  is a schematic sectional view showing a separator-integrated condenser with a gas-liquid separator according to a second embodiment of the present invention, and 
       FIG. 4B  is a schematic sectional view showing a refrigerant inlet portion of the gas-liquid separator in the separator-integrated condenser according to the second embodiment; 
       FIG. 5  is a schematic diagram showing a refrigerant cycle system according to a third embodiment of the present invention; 
       FIG. 6A  is a schematic sectional view showing a separator-integrated condenser with a gas-liquid separator according to the third embodiment, and  FIG. 6B  is a schematic sectional view showing a refrigerant inlet portion of the gas-liquid separator in the separator-integrated condenser according to the third embodiment; 
       FIG. 7  is a schematic diagram showing a refrigerant cycle system and an electronic control unit according to a fourth embodiment of the present invention; 
       FIG. 8  is a schematic diagram showing a refrigerant cycle system according to a fifth embodiment of the present invention; 
       FIG. 9  a schematic sectional view showing a separator-integrated condenser with a gas-liquid separator according to the fifth embodiment; 
       FIG. 10  is an enlarged sectional view showing a main part of the separator-integrated condenser shown in  FIG. 9 ; 
       FIG. 11  is a schematic sectional view showing a single condenser portion and a detecting method of a pressure loss in a refrigerant passage of a first heat-exchanging portion of the condenser, according to the fifth embodiment; 
       FIG. 12  is a schematic sectional view showing a separator-integrated condenser with a gas-liquid separator according to a sixth embodiment of the present invention; 
       FIG. 13  is an enlarged sectional view showing a main part of the separator-integrated condenser shown in  FIG. 12 ; 
       FIG. 14  is a schematic diagram showing a refrigerant cycle system having a separator-integrated condenser with a gas-liquid separator, according to a seventh embodiment of the present invention; 
       FIG. 15  is an enlarged sectional view showing a main part of the separator-integrated condenser shown in  FIG. 14 ; 
       FIG. 16  is a schematic diagram showing a refrigerant cycle system having a separator-integrated condenser with a gas-liquid separator, according to an eighth embodiment of the present invention; 
       FIG. 17  a schematic diagram showing a refrigerant cycle system having a separator-integrated condenser with a gas-liquid separator, according to a ninth embodiment of the present invention; 
       FIG. 18  is an enlarged sectional view showing a main part of the separator-integrated condenser shown in  FIG. 17 ; and 
       FIG. 19  is a schematic diagram showing a conventional refrigerant cycle system. 
   

   DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
   Preferred embodiments of the present invention will be described hereinafter with reference to the appended drawings. 
   (First Embodiment) 
   The first embodiment of the present invention will be now described with reference to  FIGS. 1–3 . In the first embodiment, a refrigerant cycle system shown in  FIG. 1  is typically used for a vehicle air conditioner. In  FIG. 1 , a compressor  1  is driven by a vehicle engine E through a solenoid clutch  1   a  and a belt hung thereon. High-pressure and high-temperature refrigerant is discharged from the compressor  1 , and is circulated into a separator-integrated condenser  2 . In the condenser  2 , the refrigerant is heat-exchanged with and cooled by outside air, and is condensed. The condenser  2  is disposed at a portion to be cooled by receiving running wind in a vehicle running. Specifically, the condenser  2  is disposed at a front area in an engine compartment, and is cooled by the running wind and air blown by a cooling fan (not shown). 
   A decompression device  3  decompresses refrigerant after passing through the condenser  2  to a low-pressure and gas-liquid refrigerant state. For example, the decompression device  3  is constructed with a fixed throttle such as an orifice, a nozzle and a capillary tube. The decompression device  3  may be constructed with a variable throttle capable of adjusting its open degree in accordance with pressure and a temperature of high-pressure refrigerant. An evaporator  4  is disposed to evaporate the low-pressure refrigerant flowing out of the decompression device  3  by absorbing heat from air blown by a blower (not shown) of the vehicle air conditioner. The evaporator  4  is disposed in an interior unit case (not shown) of the vehicle air conditioner to cool air flowing in the interior unit case. Air cooled by the evaporator  4  is temperature-adjusted by a heater core (not shown), and is blown into a passenger compartment. On the other hand, gas refrigerant evaporated in the evaporator  4  is sucked into the compressor  1 . 
   The separator-integrated condenser  2  includes a first heat-exchanging portion  5  and a second heat-exchanging portion  6  disposed in this order in a refrigerant flowing direction. Further, the condenser  2  includes a gas-liquid separator  7  at a high pressure side, for separating refrigerant into gas refrigerant and liquid refrigerant, between the first and second heat-exchanging portions  5 ,  6 . A liquid-refrigerant introduction passage  14 , through which all of liquid refrigerant (condensed refrigerant) after passing through the first heat-exchanging portion  5  is introduced into the gas-liquid separator  7 , is provided between the gas-liquid separator  7  and the first heat-exchanging portion  5 . A part of gas refrigerant discharged from the compressor  1  is introduced into a gas-refrigerant bypass passage  10  having a gas refrigerant throttle  10   a , and is introduced from the gas-refrigerant bypass passage  10  into the gas-liquid separator  7 . 
   In the gas-liquid separator  7 , the liquid refrigerant from the liquid-refrigerant introduction passage  14  and the discharged gas refrigerant from the gas-refrigerant bypass passage  10  are mixed with each other, and the mixed refrigerant is separated into gas refrigerant and liquid refrigerant due to a mass density difference between gas refrigerant and liquid refrigerant. The liquid refrigerant is stored at a lower portion in the gas-liquid separator  7 , and the gas refrigerant is stored at an upper portion therein. A gas-refrigerant return passage  12 , through which gas refrigerant is introduced from the gas-liquid separator  7  into the second heat-exchanging portion  6 , is connected to an inlet side of the second heat-exchanging portion  6 . Further, a liquid-refrigerant return passage  13 , through which liquid refrigerant is introduced from the gas-liquid separator  7  into the second heat-exchanging portion  6 , is connected to the inlet side of the second heat-exchanging portion  6 . 
   Next, a specific construction of the separator-integrated condenser  2  with the gas-liquid separator  7  will be described with reference to  FIGS. 2 ,  3 . The condenser  2  includes a heat-exchanging portion  8  constructed with plural flat tubes  15  horizontally extending and forming a refrigerant passage and, corrugated fins  16  connected to the plural flat tubes  15 . The first and second heat-exchanging portions  5 ,  6  are integrally connected to form the heat-exchanging portion  8 . Right and left header tanks (side tanks)  17 ,  18  are disposed at right and left sides of the heat-exchanging portion  8 , respectively, to extend in an up-down direction. Right and left ends of each flat tube  15  are connected to and communicate with the right and left header tanks  17 ,  18 , respectively. 
   An inner space of the left header tank  17  is partitioned by two partition plates  19   a ,  19   b  into upper, intermediate and lower spaces  17   a ,  17   b ,  17   c . The upper partition plate  19   a  has a throttle opening that is as the gas refrigerant throttle  10   a . An inner space of the right header tank  18  is partitioned by a partition plate  20  into upper and lower spaces  18   a ,  18   b . The lower partition plate  19   b  in the header tank  17  and the partition plate  20  in the header tank  18  are arranged at the same height position in an up-down direction of the header tanks  17 ,  18 . The first heat-exchanging portion  5  is arranged in an upper side area of the heat-exchanging portion  8 , specifically, at an upper portion of both the partition plates  19   b ,  20 . The second heat-exchanging portion  6  is arranged in a lower side area of the heat-exchanging portion  8 , specifically, at a lower portion of both the partition plates  19   b ,  20 . 
   An inlet joint  24  used as a refrigerant inlet is connected to the left header tank  17  at a portion corresponding to the intermediate space  17   b . The gas refrigerant, discharged from the compressor  1 , flows from the inlet joint  24  into the intermediate space  17   b  of the left header tank  17 . A part of the gas refrigerant, flowing into the intermediate space  17   b  from the compressor  1 , directly flows into the upper space  17   a  through the gas refrigerant throttle  10   a  opened in the upper partition plate  19   a . That is, the part of the discharged gas refrigerant flows into the upper space  17   a  while bypassing the first heat-exchanging portion  5 . A flow amount (bypass amount) of refrigerant flowing from the intermediate space  17   b  into the upper space  17   a  is set by an opening area of the gas refrigerant throttle  10   a . Further, upper and lower connection joints  17   d ,  17   e  are integrated to the left header tank  17  around upper and lower ends of the left header tank  17 , respectively. The upper and lower connection joints  17   d ,  17   e  have passage holes  17   f ,  17   g  communicating with the upper and lower spaces  17   a ,  17   c  of the left header tank  17  and screw holes  17   h ,  17   i , respectively. An outlet joint  25  is connected to the right header tank  18  at a lower side to communicate with the lower space  1818   b  of the right header tank  18 . Refrigerant from the lower space  18   b  of the right header tank  18  flows toward the decompression device  3  through the outlet joint  25 . 
   The gas-liquid separator  7  is constructed with a cylindrical tank member extending in the up-down direction, and is fixed to the connection joints  17   d ,  17   e  of the left header tank  17  having the inlet joint  24 . Specifically, the gas-liquid separator  7  has through holes  71 ,  72  horizontally provided around its upper and lower ends, respectively. Top end portions of screw portions of bolts  73 ,  74  are screwed into the screw holes  17   h ,  17   i  of the connection joints  17   d ,  17   e  through the through holes  71 ,  72 , respectively. In this way, the gas-liquid separator  7  is fixed to one of the header tanks  17 ,  18 , that is, the left header tank  17  in this example. The gas-liquid separator  7  has a refrigerant inlet  75  and a refrigerant outlet  76  around its upper and lower ends, respectively. The refrigerant inlet  75  is disposed so as to face the passage hole  17   f  of the upper connection joint  17   d , and the refrigerant outlet  76  is disposed so as to face the passage hole  17   g  of the lower connection joint  17   e . Therefore, when the gas-liquid separator  7  is fixed to the left header tank  17 , the refrigerant inlet  75  and the refrigerant outlet  76  can be connected to the passage hole  17   f  of the upper connection joint  17   d  and the passage hole  17   g  of the lower connection joint  17   e , respectively, at the same time. Here, sealing performance of each connection portion of the refrigerant inlet  75  and the refrigerant outlet  76  is ensured by an elastic seal member such as an O-ring. 
   As shown in  FIG. 3 , the refrigerant inlet  75  is disposed so as to be offset from a circular center of an inner space of the gas-liquid separator  7 . Therefore, refrigerant flows from the refrigerant inlet  75  into the inner space of the gas-liquid separator  7  substantially along a tangential line of a circular inner peripheral surface of the inner space. Therefore, as shown in  FIG. 3 , the refrigerant flows in a turn flow A in an upper inner space of the gas-liquid separator  7 , and centrifugal force is applied to the refrigerant flow due to this turn flow A. Thus, liquid refrigerant (saturated liquid refrigerant) having larger mass density is pushed to the inner peripheral surface of the gas-liquid separator  7 . Then, the liquid refrigerant drops along the inner peripheral surface, and is stored in the inner space of the gas-liquid separator  7  at the lower side. In  FIG. 2 , the line B shows a liquid surface of the liquid refrigerant in the gas-liquid separator. On the contrary, gas refrigerant (saturated gas refrigerant) having lower mass density collects around the circular center of the inner space of the gas-liquid separator  7 . Thus, a gas refrigerant area is provided in the inner space of the gas-liquid separator  7  at an upper side, that is, at an upper side of the liquid surface B of the liquid refrigerant in the gas-liquid separator  7 . 
   Thus, the refrigerant, flowing from the refrigerant inlet  75  into the gas-liquid separator  7 , is forced to be separated into liquid refrigerant and gas refrigerant, by using the centrifugal force of the turn flow A. Therefore, even if the gas-liquid separator  7  has only a small tank capacity, the refrigerant flowing into the gas-liquid separator  7  can be surely separated into liquid refrigerant and gas refrigerant. Thus, a centrifugal separator is constructed at an upper portion of the gas-liquid separator  7  around the refrigerant inlet  75 . 
   A circular pipe member  77  is disposed at a circular center area of the circular inner space of the gas-liquid separator  7  so as to extend in the up-down direction. The pipe member  77  has a gas return opening  77   a  from which gas refrigerant is sucked. The gas return opening  77   a  is provided in an outer peripheral surface of the pipe member at a position much higher than the liquid surface B of the liquid refrigerant. The gas refrigerant flows downward in an inner passage of the pipe member  77 . Further, the pipe member  77  has a liquid return opening  77   b , from which liquid refrigerant is sucked. The liquid return opening  77   b  is provided in the outer peripheral surface of the pipe member  77  at a position much lower than the liquid surface B of the liquid refrigerant. The liquid refrigerant is sucked into the inner passage of the pipe member  77 , and is mixed with the gas refrigerant sucked therein. 
   A circular plate member  77   c  having a center hole is fixed onto an outer peripheral surface of the pipe member  77  at a position slightly lower than the gas return opening  77   a . A predetermined clearance is provided between the outer peripheral surface of the circular plate member  77   c  and the inner peripheral surface of the gas-liquid separator  7 . Liquid refrigerant generated at the upper side area of the gas-liquid separator  7  drops along its inner peripheral surface through this clearance. Because the plate member  77   c  is provided, the liquid refrigerant with the liquid surface B in the gas-liquid separator  7  can be restricted from bubbling, thereby improving separating performance between the gas refrigerant and the liquid refrigerant in the gas-liquid separator  7 . The gas-liquid separator  7  has a cylindrical wall portion  78  at its bottom, and the bottom wall portion  78  has the through hole  72  horizontally provided at its bottom side and a hole portion  79  provided at an upper side of the through hole  72  in the up-down direction. A lower end of the pipe member  77  is inserted and fixed into an upper portion (large hole portion) of the hole portion  79  while an upper end of the pipe member  77  contacts an upper wall surface of the gas-liquid separator  7 . A lower portion of the hole portion  79  communicates with the refrigerant outlet  76 . Accordingly, refrigerant flows from the gas return opening  77   a  and the liquid return opening  77   b  into the pipe member  77 , and further flows into the refrigerant outlet  76  through the hole portion  79 . 
   In  FIG. 2 , the bottom wall portion  78  is integrated to the gas-liquid separator  7 . However, actually, the bottom wall portion  78  is formed as a cover member separated from the gas-liquid separator  7 , and is inserted into the gas-liquid separator  7 . A desiccant (not shown) for absorbing water contained in refrigerant is disposed in the gas-liquid separator  7 . All of the flat tubes  15  of the heat-exchanging portion  8  (first and second heat-exchanging portions  5 ,  6 ), the corrugated fins  16 , the header tanks  17 ,  18 , the connection joints  17   d ,  17   e , the inlet joint  24 , the outlet joint  25  and the like are made of aluminum, and are integrated together by brazing. 
   Next, operation of the separator-integrated condenser  2  in the first embodiment will be described. Gas refrigerant is discharged from the compressor  1 , and flows from the inlet joint  24  into the intermediate space  17   b  of the left header tank  17 . As indicated by the arrow Fa in  FIG. 2 , a main part of the gas refrigerant discharged from the compressor  1  flows into the flat tubes  15  at a lower half portion of the first heat-exchanging portion  5 , and passes therethrough horizontally. Then, the main part of the discharged gas refrigerant is U-turned in the upper space  18   a  of the header tank  18 , and flows into the flat tubes  15  at an upper half portion of the first heat-exchanging portion  5  horizontally as shown by the arrow Fb. In a normal cycle operation condition, the gas refrigerant discharged from the compressor  1  radiates heat to outside air, and is condensed while flowing in a U-turn refrigerant passage of the first heat-exchanging portion  5 . Therefore, the condensed refrigerant (liquid refrigerant) flows into the upper space  17   a  of the left header tank  17 . When the cycle operation condition changes, gas-liquid refrigerant, having a predetermined dry degree, sometimes flows into the upper space  17   a.    
   On the other hand, a part of the discharged gas refrigerant flowing from the compressor  1  into the intermediate space  17   b  passes through the gas refrigerant throttle  10   a  of the upper partition plate  19   a , and directly flows into the upper space  17   a  of the left header tank  17 . Accordingly, the part of the discharged gas refrigerant and the condensed refrigerant (liquid refrigerant) after passing through the first heat-exchanging portion  5  are mixed in the upper space  17   a  of the left header tank  17 . As indicated by the arrow Fc in  FIG. 2 , the mixed refrigerant passes through the passage hole  17   f  of the upper connection joint  17   d , and flows into the refrigerant inlet  75  of the gas-liquid separator  7 . The refrigerant flowing into the refrigerant inlet  75  is separated by the centrifugal separator into liquid refrigerant (saturated liquid refrigerant) and gas refrigerant (saturated gas refrigerant). The liquid refrigerant drops in the gas-liquid separator  7 , and is stored therein at the lower side area. As indicated by the arrow Fd in  FIG. 2 , a part of the stored liquid refrigerant flows into the pipe member  77  from the liquid return opening  77   b  located around the lower end of the pipe member  77 . As indicated by the arrow Fe in  FIG. 2 , the gas refrigerant flows into the inner space of the pipe member  77  from the gas return opening  77   a.    
   An open area of the liquid return opening  77   b  is set much smaller than an open area of the gas return opening  77   a , thereby restricting liquid refrigerant flowing into the liquid return opening  77   b . The gas refrigerant and the liquid refrigerant flows from the pipe member  77  into the lower space  17   c  of the left header tank  17  through the hole portion  79 , the refrigerant outlet  76  and the passage hole  17   g  of the lower connection joint  17   e  in this order, as indicated by the arrow Ff in  FIG. 2 . 
   The gas refrigerant and the liquid refrigerant are mixed in the refrigerant passage, and pass through the flat tubes  15  in the second heat-exchanging portion  6  as indicated by the arrow Fg in  FIG. 2 . While the refrigerant passes through the flat tubes  15  in the second heat-exchanging portion  6 , the refrigerant further radiates heat to outside air to be super-cooled, and flows into the lower space  18   b  of the left header tank  18 . Thereafter, the super-cooled refrigerant flows outside of the condenser  2  from the outlet joint  25 , and flows toward the decompression device  3 . A part of the liquid refrigerant, stored in the gas-liquid separator  7 , is always introduced into the second heat-exchanging portion  6 , and is circulated into the refrigerant cycle. Therefore, lubricating oil contained in liquid refrigerant is surely returned into the compressor  1 , thereby improving lubricating performance of the compressor  1 . 
   In order to form the above-described refrigerant flow, all of the condensed refrigerant (liquid refrigerant) after passing through the first heat-exchanging portion  5  and the part of the discharged gas refrigerant flowing from the inlet joint  24  into the left header tank  17  are mixed and heat-exchanged with each other in the upper space  17   a  of the left header tank  17 . In this way, the refrigerant, flowing from the upper space  17   a  into the gas-liquid separator  7 , is in the gas-liquid two-phase state having a dry degree corresponding to a super-heating degree of the discharged gas refrigerant of the compressor  1 . 
   As a result, the amount of liquid refrigerant stored in the gas-liquid separator  7  is an amount corresponding to the super-heating degree of the gas refrigerant discharged from the compressor  1 . That is, the amount of liquid refrigerant stored in the gas-liquid separator  7  can be adjusted in accordance the change of the super-heating degree of the gas refrigerant discharged from the compressor  1 . An amount of the gas refrigerant, introduced from the gas-liquid separator  7  into the second heat-exchanging portion  6 , is changed by adjusting this liquid refrigerant amount stored in the gas-liquid separator, thereby adjusting an amount of refrigerant circulated in the refrigerant cycle and adjusting the super-heating degree of the gas refrigerant discharged from the compressor  1 . Since the compression of the compressor  1  is performed with an isentropic change basically, if the super-heating degree of the gas refrigerant discharged from the compressor  1  can be controlled, the super-heating degree of the gas refrigerant at an outlet of the evaporator  4  can be also controlled. In this way, in the first embodiment, dimension difference of the refrigerant passage in manufacturing is not greatly affected to the adjustment operation of refrigerant amount in the refrigerant cycle system where the flow amount of a circulated refrigerant is adjusted by adjusting the amount of liquid refrigerant stored in the gas-liquid separator  7  arranged at the high pressure side. 
   Next, advantages of the first embodiment will be specifically described. A flow amount ratio between the condensed refrigerant (liquid refrigerant) introduced into the gas-liquid separator  7  and the gas refrigerant introduced into the gas-liquid separator  7  from the compressor  1  is set at a predetermined ratio suitable for the refrigerant cycle system so that the super-heating information of the gas refrigerant discharged from the compressor  1  can be suitably fed back into the gas-liquid separator  7 . For example, as described above, the flow amount ratio of the liquid refrigerant to the gas refrigerant flowing into the gas-liquid separator  7  is set about 1:2. In the first embodiment, all of the condensed refrigerant after passing through the first heat-exchanging portion  5  is introduced into the gas-liquid separator  7 . Therefore, in the first embodiment, an amount of the liquid refrigerant flowing into the gas-liquid separator  7  can be effectively increased. Therefore, the amount of the gas refrigerant flowing from the compressor  1  into the gas-liquid separator  7  can be also effectively increased. 
   As a result, a passage diameter of the gas refrigerant throttle  10   a , for regulating the amount of the gas refrigerant flowing from the compressor into the gas-liquid separator  7 , can be increased to a dimension (e.g., Ø5.5 mm). The passage diameter of φ5.5 mm in the first embodiment is larger than twice of the passage diameter (Ø2.5 mm) in the above-described related art. Here, when the passage diameter of the gas refrigerant throttle  10   a  is machined, dimension difference of the passage diameter of the gas refrigerant throttle  10   a  is caused in the machining. Further, the passage diameter of the gas refrigerant throttle  10   a  is changed by solder invasion into the gas refrigerant throttle  10   a  in brazing of the condenser  2  and the like. Therefore, the passage diameter of the gas refrigerant throttle  10   a  actually formed is generally changed to a some degree from the design diameter. 
   However, in the first embodiment, the passage diameter of the gas refrigerant throttle  10   a  can be largely increased than in the related art. Therefore, even when the passage diameter of the gas refrigerant throttle  10  is changed in the manufacturing step, a change ratio of the passage diameter can be effectively reduced. That is, a flow amount change of the gas refrigerant in the gas refrigerant throttle  10   a  due to the dimension difference in the passage diameter can be effectively. Therefore, the flow-amount change ratio of the gas refrigerant to the liquid refrigerant flowing into the gas-liquid separator  7  can be reduced, and the dimension difference of the refrigerant passage in the manufacturing step is not greatly affected to the adjustment operation of the refrigerant flow amount in the refrigerant cycle. Accordingly, even if the passage dimension changes in the manufacturing step by some degree, the refrigerant amount circulated in the refrigerant cycle can be suitably adjusted to a predetermined target amount in accordance with the super-heating degree of the discharged gas refrigerant from the compressor  1 . 
   Next, the correlation between the specific construction shown  FIGS. 2 ,  3  and the refrigerant circuit construction shown in  FIG. 1  will be described. The gas-refrigerant bypass passage  10  shown in  FIG. 1  is constructed with the gas refrigerant throttle  10   a , the upper space  17   a  of the left header tank  17  and the passage hole  17   f  of the upper connection joint  17   d  shown in  FIGS. 2 ,  3 . The liquid-refrigerant introduction passage  14  in  FIG. 1  is constructed with the upper space  17   a  of the left header tank  17  and the passage hole  17   f  of the upper connection joint  17   d  shown  FIGS. 2 ,  3 . The gas-refrigerant return passage  12  shown in  FIG. 1  is constructed with the gas return opening  77   a , the inner passage of the pipe member  77 , the hole portion  79 , the refrigerant outlet  76  and the passage hole  17   g  of the lower connection joint  17   e  shown in  FIGS. 2 ,  3 . The liquid-refrigerant return passage  13  shown in  FIG. 1  is constructed with the liquid return opening  77   b , the inner passage of the pipe member  77 , the hole portion  79 , the refrigerant outlet  76  and the passage hole  17   g  of the lower connection joint  17   e  shown in  FIGS. 2 ,  3 . Here, the upper space  17   a  of the header tank  17  is used as a refrigerant mixing portion for mixing the gas refrigerant from the compressor  1  and the liquid refrigerant from the first heat-exchanging portion  5 , in the present invention. 
   (Second Embodiment) 
   In the above-described first embodiment, the gas-liquid separator  7  is fixed by using the bolts  73 ,  74  to the left header tank  17  of the condenser  2 . However, in the second embodiment, as shown in  FIG. 4 , the gas-liquid separator  7  is integrally brazed to the left header tank  17  of the condenser  2 . Specifically, the gas-liquid separator  7  has a flat outer-wall surface on a side having the refrigerant inlet  75 . That is, the gas-liquid separator  7  has a flat outer-wall surface that is bonded to the left header tank  17  by the brazing. The gas-liquid separator  7  is integrally brazed to the left header tank  17  while its flat outer-wall surface contacts an outer wall surface of the left header tank  17 . Therefore, in the second embodiment, the components such as the connection joints  17   d ,  17   e  and the bolts  73 ,  74  in the first embodiment can be eliminated, thereby simplifying the construction, and eliminating screwing work of the bolts  73 ,  74 . In the second embodiment, the gas-liquid separator  7  may be brazed to the left header tank  17  through a both-surface clad material. That is, the both-surface clad material is clad with a brazing material on both the surfaces, and is disposed between the flat outer-wall surface of the gas-liquid separator  7  and the flat outer-wall surface of the left header tank  17 . In the second embodiment, the other parts are similar to those of the above-described first embodiment, and the description thereof is omitted. 
   (Third Embodiment) 
   In the above-described first and second embodiments, the liquid-refrigerant return passage  13  into which a part of liquid refrigerant stored in the gas-liquid separator  7  flows, is connected to the inlet side of the second heat-exchanging portion  6 . However, in the third embodiment, as shown in  FIG. 5 , the liquid-refrigerant return passage  13  is connected to the outlet side of the second heat-exchanging portion  6 . Further, as in the second embodiment, the gas-liquid separator  7  is integrally brazed to the left header tank  17 . 
   In the third embodiment, as shown in  FIG. 6A , three partition plates  19   a ,  19   b ,  19   c  are arranged in the up-down direction in the left header tank  17  of the condenser  2 , thereby partitioning the inner space of the left header tank  17  into four spaces  17   a ,  17   b ,  17   c ′,  17   c ″ in the up-down direction. The partition plates  19   a ,  19   b , the upper space  17   a  and the intermediate space  17   b  in the third embodiment correspond to those in the first and second embodiments, respectively. On the other hand, the partition plate  19   c  in the third embodiment is newly added to the header tank  17  the first and second embodiments. Therefore, the lower space  17   c  in the first and second embodiments is partitioned by the partition plate  19   c  into an intermediate space  17   c ′ and a lowest space  17   c ″ in the third embodiment. 
   In the third embodiment, the pipe member  77  is formed into L-shape, and the lower outlet of the L-shaped pipe member  77  communicates with the intermediate space  17   c ′. Therefore, the L-shaped pipe member  77  is used as the gas-refrigerant return passage  12  shown in  FIG. 5 . On the other hand, the outlet joint  25  is disposed on the left header tank  17  at a position corresponding to the lowest space  17   c ″ under the partition plate, and a part of liquid refrigerant stored in the gas-liquid separator  7  is introduced through the liquid-refrigerant return passage  13  into the lowest space  17   c ″. The liquid-refrigerant return passage  13  can be constructed with a though hole penetrating through a wall between the gas-liquid separator  7  and the left header tank  17 . 
   In the third embodiment, the refrigerant is centrifuged into gas refrigerant and liquid refrigerant in the gas-liquid separator  7 . The gas refrigerant collected at the upper side in the gas-liquid separator  7  flows into the pipe member  77  from the gas return opening  77   a  located at the upper side of the pipe member  77 . Then, the gas refrigerant flows in the inner space of the pipe member  77  as indicated by the arrow Fh in  FIG. 6A , and flows into the intermediate space  17   c ′. The intermediate space  17   c ′ is provided to define an inlet portion of the second heat-exchanging portion  6 . The gas refrigerant flows from the intermediate space  17   c ′ into the flat tubes  15  in the upper portion of the second heat-exchanging portion  6 , and is U-turned in the lower space  18   b  of the header tank  18  as indicated by the arrow Fi in  FIG. 6A . Then, the refrigerant flows into the flat tubes  15  in the lower portion of the second heat-exchanging portion  6 , and flows into the lowest space  17   c ″ of the left header tank  17 . 
   In the third embodiment, a U-shaped refrigerant passage is formed also in the second heat-exchanging portion  6 , and the saturated gas refrigerant radiates heat to outside air in the U-shaped refrigerant passage. Thus, the saturated gas refrigerant is condensed and super-cooled in the U-shaped refrigerant passage of the second heat-exchanging portion  6 , and flows into the lowest space  17   c ″. In the lowest space  17   c ″, the super-cooled liquid refrigerant from the second heat-exchanging portion  6  and the saturated liquid refrigerant from the gas-liquid separator  7  through the liquid-refrigerant return passage  13  are mixed. The mixed refrigerant flows outside from the condenser  2  through the outlet joint  25 , and flows toward the inlet side of the decompression device  3 . In the third embodiment, because the U-shaped refrigerant passage is constructed also in the second heat-exchanging portion  6 , the number of turns in the refrigerant passage can be increased in the condenser  2 , and heat-exchanging performance in the condenser  2  can be improved. 
   (Fourth Embodiment) 
   In the above-described first to third embodiments, a part of gas refrigerant discharged from the compressor  1  is directly introduced into the gas-liquid separator  7 , thereby changing an amount of liquid refrigerant stored in the gas-liquid separator  7  in accordance with a change of the super-heating degree of the discharged gas refrigerant from the compressor  1 . However, in the fourth embodiment, as shown in  FIG. 7 , the gas refrigerant from the compressor  1  is not directly introduced into the gas-liquid separator  7 , and a heating device  35  is provided. The heating device  35  adjusts a refrigerant heating amount in accordance with the super-heating degree of gas refrigerant at the outlet of the evaporator  4 , thereby adjusting the amount of liquid refrigerant stored in the gas-liquid separator  7 . In the fourth embodiment, the heating device  35  is constructed with an electric heater. 
   Specifically, in the fourth embodiment, as shown in  FIG. 7 , the gas-refrigerant bypass passage  10  having the gas refrigerant throttle  10   a  is eliminated from the refrigerant passage in the separator-integrated condenser  2  shown in  FIG. 1  (in the first embodiment). Further, in the fourth embodiment, a refrigerant temperature sensor  30  and a refrigerant pressure sensor  31  are provided on a refrigerant outlet pipe of the evaporator  4 , and the electric heater  35  is provided on the gas-liquid separator  7  at its bottom side. Detection signals from the both the sensors  30 ,  31  are input to a super-heating degree determining unit (determining unit)  33  of an electronic control unit  32 , and the super-heating degree determining unit  33  determines the super-heating degree of gas refrigerant at the outlet of the evaporator  4 . A super-heating degree determining signal is output from the super-heating degree determining unit  33  to a heating-amount control unit (heating controller)  34  of the electronic control unit  32 . 
   The heating-amount control unit  34  controls an electric current supplied to the electric heater  35  so as to increase a heating amount of the electric heater  35  as the super-heating degree of gas refrigerant at the outlet of the evaporator  4  increases. The heating amount of the electric heater  35  is increased as the super-heating degree of gas refrigerant at the outlet of the evaporator  4  increases, thereby increasing an evaporation amount of liquid refrigerant stored in the gas-liquid separator  7 . Therefore, an amount of refrigerant circulated in the refrigerant cycle is increased as the super-heating degree of gas refrigerant at the outlet of the evaporator  4  increases, thereby preventing the super-heating degree from increasing. On the contrary, when the super-heating degree of gas refrigerant at the outlet of the evaporator  4  reduces, the heating amount of the electric heater  35  is reduced. Therefore, an evaporation amount of liquid refrigerant stored in the gas-liquid separator  7  is reduced, that is, an amount of liquid refrigerant stored in the gas-liquid separator  7  is increased, thereby preventing the super-heating degree of gas refrigerant at the outlet of the evaporator  4  from reducing. 
   In the fourth embodiment, the heating amount for heating the liquid refrigerant stored in the gas-liquid separator  7  is electrically adjusted in accordance with the super-heating degree of gas refrigerant at the outlet of the evaporator  4 , thereby controlling the super-heating degree of gas refrigerant at the outlet of the evaporator  4  in a predetermined super-heating area. 
   Even in the fourth embodiment, all of the condensed liquid refrigerant after passing through the first heat-exchanging portion  5  is introduced into the gas-liquid separator  7  through the liquid-refrigerant introduction passage  14 . Therefore, an amount of liquid refrigerant introduced into the gas-liquid separator  7  can be increased. Further, as the amount of liquid refrigerant introduced into the gas-liquid separator  7  increases, the heating amount of the electric heater  35  can be set relatively larger. As a result, even if the heating amount of the electric heater  35  deviates from a suitable heating amount due to detection errors of both the sensors  30 ,  31  and the likes, a deviation ratio between an actual heating amount and the suitable heating amount can be reduced. Accordingly, the adjusting operation of a refrigerant amount circulated in the refrigerant cycle is not largely affected by the heating-amount deviation of the electric heater  35 . Thus, the super-heating control of gas refrigerant at the outlet of the evaporator  4  can be performed even when the heating-amount deviation of the electric heater  35  is caused. 
   In the fourth embodiment, the super-heating degree of the gas refrigerant at the outlet of the evaporator  4  is determined, and the heating amount of the electric heater  35  for heating liquid refrigerant stored in the gas-liquid separator  7  is controlled, thereby directly controlling the super-heating degree of gas refrigerant at the outlet of the evaporator  4 . However, the refrigerant temperature sensor  30  and the refrigerant pressure sensor  31  may be provided at the discharge side of the compressor  1 . In this case, the super-heating degree of gas refrigerant discharged from the compressor  1  is determined, and the heating amount of the electric heater  35  is controlled, thereby controlling the super-heating degree of gas refrigerant discharged from the compressor  1 , and indirectly controlling the super-heating degree of gas refrigerant at the outlet of the evaporator  4 . Further, a heating device using a hot water as a heat source may be provided as the heating device for heating the liquid refrigerant stored in the gas-liquid separator  7 , in place of the electric heater  35 . In this case, a flow amount or a temperature of hot water is adjusted by an electric control valve, thereby adjusting the heating amount of the liquid refrigerant in the gas-liquid separator  7 . 
   (Fifth Embodiment) 
   In the above-described first embodiment of the present invention, as shown in  FIG. 1 , an amount of the gas refrigerant to be introduced into the gas-liquid separator  7  is set by the gas refrigerant throttle  10   a . However in the fifth embodiment, as shown in  FIG. 8 , a control valve  130  is provided in the gas-refrigerant bypass passage  10  in place of the gas refrigerant throttle  10   a . Therefore, in the fifth embodiment, the flow amount ratio between the liquid refrigerant and the gas refrigerant to be introduced into the gas-liquid separator  7  can be accurately adjusted by adjusting the opening degree of the control valve  130 . 
   Next, a specific construction of the separator-integrated condenser  2  according to the fifth embodiment will be described with reference to  FIGS. 9 and 10 . The condenser  2  includes the heat-exchanging portion  8  constructed with plural flat tubes  15  horizontally extending, and corrugated fins  16  connected to the plural flat tubes  15 . The first and second heat-exchanging portions  5 ,  6  are integrally connected to form the heat-exchanging portion  8 . The right header tank  18  has the same structure as that in the above-described first embodiment. 
   On the other hand, a left header tank  117  of the condenser  2  is integrally brazed to a gas-liquid separator  7 . An inner space of the left header tank  117  is partitioned by two partition plates  119   a ,  119   b  into upper, intermediate and lower spaces  117   a ,  117   b ,  117   c . The lower partition plate  119   b  in the header tank  117  and the partition plate  20  in the header tank  18  are arranged at the same height position in an up-down direction of the header tanks  117 ,  18 . The first heat-exchanging portion  5  is arranged in an upper side area of the heat-exchanging portion  8 , specifically, at an upper portion of both the partition plates  119   b ,  20 . The second heat-exchanging portion  6  is arranged in a lower side area of the heat-exchanging portion  8 , specifically, at a lower portion of both the partition plates  119   b ,  20 . 
   The inlet joint  24  used as a refrigerant inlet is connected to the left header tank  117  at a portion corresponding to the intermediate space  117   b . The inlet joint  24  is connected to a refrigerant discharge side pipe of the compressor  1 . An upper connection joint  117   d  is connected to a side wall surface of the header tank  117  at an upper area corresponding to the upper space  117   a  and an upper portion of the intermediate space  117   b , and a lower connection joint  117   e  is connected to the header tank  117  at a position around the lower end. 
     FIG. 10  is an enlarged view of the upper connection joint  117   d . An intermediate partition wall  117   f  is provided in the upper connection joint  117   d , so that refrigerant passages  117   g ,  117   h  are formed in the upper connection joint  117   d  above and below the intermediate partition wall  117   f . The lower refrigerant passage  117   g  of the upper connection joint  117   d  communicates with the intermediate space  117   b  of the left header tank  117  through a first communication hole  117   i  provided in a side wall of the left header tank  117 . 
   Accordingly, gas refrigerant, discharged from the compressor  1 , flows from the inlet joint  24  into the intermediate space  117   b . Then, a part of the gas refrigerant flows from the intermediate space  117   b  directly into the lower refrigerant passage  117   g  through the first communication hole  117   i . Then, the gas refrigerant flows into the upper refrigerant passage  117   h  through a throttle hole  117   j  provided in the intermediate partition wall  117   f . In this way, as shown in  FIGS. 9 ,  10 , the gas-refrigerant bypass passage  10  is constructed with the first communication hole  117   i , the lower refrigerant passage  117   g  and the throttle hole  117   j.    
   The other part of gas refrigerant flowing into the intermediate space  117   b  from the inlet joint  24  passes through the flat tubes  15  of the lower area of the first heat-exchanging portion  5 , the upper space  18   a  of the header tank  18 , and the flat tubes  15  of the upper area of the first heat-exchanging portion  5  to be cooled and condensed. The condensed refrigerant flows into the upper space  117   a  of the header tank  117 . 
   The upper refrigerant passage  117   h  communicates with the upper space  117   a  of the left header tank  117  through a second communication hole  117   k  provided in the side wall of the left header tank  117 . Therefore, the condensed refrigerant (liquid refrigerant) flowing into the upper space  117   a  of the left header tank  117  flows into the upper refrigerant passage  117   h  through the second communication hole  117   k . In this way, the liquid-refrigerant introduction passage  14  is constructed with the upper space  117   a  and the second communication hole  117   k . Both of the gas refrigerant from the throttle hole  117   j  and the liquid refrigerant from the second communication hole  117   k  flow into the upper refrigerant passage  117   h  of the upper connection joint  17   d , and are mixed therein. That is, in the fifth embodiment, the gas-liquid mixing portion is constructed with the upper refrigerant passage  117   h  of the upper connection joint  117   d.    
   The throttle hole  117   j  is a circular hole, and forms a smallest passage area in the gas-refrigerant bypass passage  10 , thereby regulating and setting a gas-refrigerant bypass amount. A valve body  130   a , movable in a hole-penetrating direction of the throttle hole  117   j , is provided in the upper connection joint  117   d . The valve body  130   a  has a circular-cone top end portion that is opposite to the throttle hole  117   j , and a male screw portion  130   b . The male screw portion  130   b  is provided to be engaged with a female screw portion  130   c  formed in a lower wall surface of the upper connection joint  117   d . Therefore, the circular-cone top end portion of the valve body  130   a  can be inserted into and drawn out from the throttle hole  117   j  by using a suitable tool. The control valve  130  is constructed with the valve body  130   a , the male screw portion  130   b  and the female screw portion  130   c.    
   As shown in  FIG. 9 , the gas-liquid separator  7  includes a cylindrical tank body  170  longitudinally extending in the up-down direction, and upper and lower covers  171 ,  172 . The upper and lower covers  171 ,  172  close upper and lower open ends of the tank body  170 , respectively. The members  170 ,  171 ,  172  are connected integrally with each other, thereby forming therein a space  173  where refrigerant is separated into gas refrigerant and liquid refrigerant. 
   The upper and lower covers  171 ,  172  are disposed opposite to the upper and lower connection joints  117   d ,  117   e , and are fixed to the upper and lower connection joints  117   d ,  117   e  by screw members such as blots (not shown), respectively. The upper cover  171  has a refrigerant inlet passage  174  therein, and the upper passage (gas-liquid mixing portion)  117   h  of the upper connection joint  17   d  communicates with an upper portion of the inner space  173  through the refrigerant inlet passage  174 . The lower cover  172  has a refrigerant outlet passage  175  therein, and the refrigerant outlet passage  175  communicates with the lower space  117   c  of the left header tank  117  through a refrigerant passage  117   m  of the lower connection joint  117   e  and a third communication hole  117   n  provided in the side wall of the left header tank  117 . 
   Thus, the gas-liquid separator  7  is integrated to the side wall of the left header tank  117  through the upper and lower connection joints  117   d ,  117   e . At this time, the refrigerant inlet passage  174  and the refrigerant outlet passage  175  of the gas-liquid separator  7  communicate with the upper and lower spaces  117   a ,  117   b  of the header tank  117 , respectively. Here, an elastic seal member (not shown) such as an O-ring is disposed between the refrigerant inlet passage  174  and the upper connection joint  117   d , and an elastic seal member is disposed between the refrigerant outlet passage  175  and the lower connection joint  117   e . Therefore, sealing performance can be ensured between the refrigerant inlet passage  174  and the upper connection joint  117   d , and between the refrigerant outlet passage  175  and the lower connection joint  117   e.    
   Further, the refrigerant inlet passage  174  is disposed so as to be offset from a circular center of the circular inner space  173  of the gas-liquid separator  7 . Therefore, as shown in  FIG. 9 , the turn flow A of refrigerant is formed in an upper inner area of the circular inner space  173 . Further, a desiccant  177  for removing water contained in the refrigerant is disposed in the circular inner space  173  of the gas-liquid separator  7 . 
   Thus, the refrigerant, flowing from the refrigerant inlet passage  174  into the gas-liquid separator  7 , is forced to be separated into liquid refrigerant and gas refrigerant, by using the centrifugal force of the turn flow A. Therefore, even if the gas-liquid separator  7  has only a small tank capacity, the refrigerant flowing into the gas-liquid separator  7  can be surely separated into liquid refrigerant and gas refrigerant. Accordingly, a centrifugal separator is constructed at an upper portion of the inner space  173  of the gas-liquid separator  7  around the refrigerant inlet passage  175 . 
   A circular pipe member  176  is disposed at a circular center area of the circular inner space  173  of the gas-liquid separator  7  so as to extend in the up-down direction. The top end of the pipe member  176  is supported in and is fixed to the upper cover  171 , the bottom end of the pipe member  176  is inserted into an upper end opening of the refrigerant outlet passage  175  of the lower cover  172  to be supported in and fixed to the lower cover  172 . 
   The pipe member  176  has a gas return opening  176   a  from which gas refrigerant is sucked. The gas return opening  176   a  is provided in an outer peripheral surface of the pipe member  176  at a position much higher than the liquid surface B of the liquid refrigerant. The gas refrigerant flows downward in an inner passage of the pipe member  176 . Therefore, the gas-refrigerant return passage  12  is constructed with the gas return opening  176   a  and the like. 
   Further, the pipe member  176  has a liquid return opening  176   b , from which liquid refrigerant is sucked. The liquid return opening  176   b  is provided in the outer peripheral surface of the pipe member  176  at a position much lower than the liquid surface B of the liquid refrigerant. The liquid refrigerant is sucked into the inner passage of the pipe member  176 , and is mixed with the gas refrigerant sucked therein to be introduced into the refrigerant outlet passage  175 . Therefore, the liquid-refrigerant return passage  13  is constructed with the liquid return opening  176   b  and the like. 
   Refrigerant from the refrigerant outlet passage  175  of the gas-liquid separator  7  flows into the lower space  117   c  of the header tank  117  through the refrigerant passage  117   m  of the lower connection joint  117   e  and the third communication hole  117   n  of the header tank  117 , and is further heat-exchanged with outside air in the flat tubes  15  of the second heat-exchanging portion  6  to be super-cooled. Thereafter, the super-cooled refrigerant flows into the lower space  18   b  of the header tank  18 , and flows toward the decompression device  3  through the outlet joint  25 . 
   All of the flat tubes  15  of the heat-exchanging portion  8  (first and second heat-exchanging portions  5 ,  6 ), the corrugated fins  16 , the header tanks  117 ,  18 , the connection joints  117   d ,  117   e , the inlet joint  24 , the outlet joint  25  and the like are made of aluminum, and are integrated together by brazing. 
   Next, operation of the fifth embodiment will be now described. Gas refrigerant is discharged from the compressor  1 , and flows from the inlet joint  24  into the intermediate space  117   b  of the left header tank  117 . Then, the refrigerant flowing into the intermediate space  117   b  of the header tank  117  is branched into a refrigerant flow toward the first heat-exchanging portion  5  and a refrigerant flow toward the upper connection joint  117   d  while bypassing the first heat-exchanging portion  5 . 
   Therefore, a part of the gas refrigerant discharged from the compressor  1  passes through the first heat-exchanging portion  5 , and is U-turned in the upper space  18   a  of the header tank  18 , as shown by the arrow Fb in  FIG. 9 . In a normal cycle operation condition, the gas refrigerant discharged from the compressor  1  radiates heat to outside air, and is condensed while flowing in a U-turn refrigerant passage of the first heat-exchanging portion  5 . Therefore, the condensed refrigerant (liquid refrigerant) flows into the upper space  117   a  of the left header tank  117 , and flows into the upper refrigerant passage  117   h  of the upper connection joint  117   d  through the second communication hole  117   k.    
   On the other hand, the other part of the discharged gas refrigerant flows from the intermediate space  117   b  directly into the upper refrigerant passage  117   h  through the first communication hole  117   i , the lower refrigerant passage  117   g  and the throttle hole  117   j . Therefore, all of the condensed refrigerant (liquid refrigerant) after passing through the first heat-exchanging portion  5  and the gas refrigerant from the throttle hole  117   j  are mixed in the upper refrigerant passage  117   h . Then, the mixed refrigerant flows into the refrigerant inlet passage  174  of the gas-liquid separator  7 , and is introduced into the upper portion of the circular inner space  173 . The mixed refrigerant flows in the upper portion of the circular inner space  173  in the turn flow A, and is separated into gas refrigerant and liquid refrigerant by using the centrifugal force of the turn flow A. The liquid refrigerant drops downwardly to be stored in the gas-liquid separator  7  at the lower side. 
   A part of liquid refrigerant in the gas-liquid separator  7  flows into the inner space of the pipe member  176  through the liquid return opening  176   b . Simultaneously, gas refrigerant in the upper portion of the gas-liquid separator  7  flows into the inner space of the pipe member  176  through the gas return opening  176   a . Generally, the opening area of the liquid return opening  176   b  is set greatly smaller than the opening area of the gas return opening  176   a , so that the amount of the liquid refrigerant flowing into the liquid return opening  176   b  is set at a very small amount. 
   The gas refrigerant and the liquid refrigerant, flowing into the pipe member  176  through the gas return opening  176   a  and the liquid return opening  176   b , is introduced into the lower space  117   c  of the left header tank  117  through the refrigerant outlet passage  175 , the refrigerant passage  117   m  of the lower connection joint  117   e  and the third communication hole  117   n  of the left header tank  117  in this order. 
   The gas refrigerant and the liquid refrigerant are mixed in the refrigerant passages, and pass through the flat tubes  15  in the second heat-exchanging portion  6  as indicated by the arrow Fg in  FIG. 9 . While the refrigerant passes through the flat tubes  15  in the second heat-exchanging portion  6 , the refrigerant further radiates heat to outside air to be super-cooled, and flows into the lower space  18   b  of the right header tank  18 . Thereafter, the super-cooled refrigerant flows outside of the condenser  2  from the outlet joint  25 , and flows toward the decompression device  3 . 
   In the fifth embodiment, a part of the liquid refrigerant, stored in the gas-liquid separator  7 , is always introduced into the second heat-exchanging portion  6  through the liquid return opening  176   b , and is circulated into the refrigerant cycle. Therefore, lubricating oil contained in liquid refrigerant is surely returned into the compressor  1 , thereby improving lubricating performance of the compressor  1 . 
   In order to form the above-described refrigerant flow, all of the condensed refrigerant (liquid refrigerant) after passing through the first heat-exchanging portion  5  and the part of the discharged gas refrigerant flowing from the inlet joint  24  into the left header tank  17  are mixed and heat-exchanged with each other in the upper refrigerant passage  117   h  of the upper connection joint  117   d . In this way, the refrigerant, flowing from the upper refrigerant passage  117   h  into the gas-liquid separator  7 , is in the gas-liquid two-phase state having a dry degree corresponding to a super-heating degree of the discharged gas refrigerant of the compressor  1 . 
   As a result, the amount of liquid refrigerant stored in the gas-liquid separator  7  is an amount corresponding to the super-heating degree of the gas refrigerant discharged from the compressor  1 . That is, the amount of liquid refrigerant stored in the gas-liquid separator  7  can be adjusted in accordance the change of the super-heating degree of the gas refrigerant discharged from the compressor  1 . An amount of the gas refrigerant, introduced from the gas-liquid separator  7  into the second heat-exchanging portion  6 , is changed by adjusting this liquid refrigerant amount stored in the gas-liquid separator  7 , thereby adjusting an amount of refrigerant circulated in the refrigerant cycle and adjusting the super-heating degree of the gas refrigerant discharged from the compressor  1 . Since the compression of the compressor  1  is performed with an isentropic change basically, if the super-heating degree of the gas refrigerant discharged from the compressor  1  can be controlled, the super-heating degree of the gas refrigerant at an outlet of the evaporator  4  can be also controlled. 
   In the refrigerant cycle system of the fifth embodiment, the refrigerant circulation amount is adjusted by adjusting the amount of liquid refrigerant staying in the gas-liquid separator  7 . Specifically, a flow ratio between the gas refrigerant directly introduced into the gas-liquid separator  7  through the gas-refrigerant bypass passage  10  and the liquid refrigerant introduced from the liquid refrigerant introduction passage  14  into the gas-liquid separator  7  is controlled to a set ratio, so that the refrigerant circulation amount in the refrigerant cycle and the super-heating degree of the gas refrigerant discharged from the compressor  1  can be controlled. 
   Next, adjusting operation of the control valve  130  will be described.  FIG. 11  shows a single condenser portion of the condenser  2  after a brazing process is finished, before being assumed with the gas-liquid separator  7 . In this state of the condenser  2  shown in  FIG. 11 , a pressure loss in the refrigerant passage of the first heat-exchanging portion  5  is detected. When the pressure loss is detected, the valve body  130   a  of the control valve  130  is rotated by the suitable tool to be positioned at an entirely closed position of the throttle hole  117   j . In this state, pressure detecting pipes  131 ,  132  are connected to the inlet joint  24  and the upper refrigerant passage  117   h  of the upper connection joint  117   d , respectively. An inlet pressured detecting point  131   a  and an outlet pressure detecting point  132   a  are set in the pressure detecting pipes  131 ,  132 , respectively. 
   A fluid compressor (not shown) for supplying a predetermined pressure fluid into the pressure detecting pipe  131 , specifically, an air compressor is connected to an inlet side of the pressure detecting pipe  131 . An outlet side of the pressure detecting pipe  132  is opened to the atmospheric air. Predetermined-pressure air is supplied from the air compressor into the refrigerant passage of the first heat-exchanging portion  5 , and pressure P 1  at the inlet pressure detecting point  131   a  and pressure P 2  at the outlet pressure detecting point  132   a  are detected. Pressure loss ΔP (P 1 –P 2 ) is calculated based on detected pressure P 1  and detected pressure P 2 . The pressure loss ΔP is a value showing an affecting degree of dimension differences in manufacturing and due to solder invasion in the condenser  2 . Here, a passage area of the throttle hole  117   j , required to maintain the ratio between the gas refrigerant bypass amount and the liquid refrigerant amount at a predetermined set ratio, is calculated beforehand. That is, a relationship between a predetermined set position of the valve body  130   a  of the control valve  130  and the pressure loss ΔP is calculated beforehand. Here, the predetermined set position is a rotation angle position from the entirely closed position of the valve body  130   a.    
   In this way, the valve body  130   a  of the control valve  130  is rotated to a set rotation angle position corresponding to the pressure loss ΔP, by a rotation angle from the entirely closed position. Therefore, the passage area of the throttle hole  117   j  can be suitably set in consideration of the dimension difference in the manufacturing, the solder invasion and the like. Thus, the ratio between the gas refrigerant bypass amount and the liquid refrigerant amount introduced into the gas-liquid separator  7  can be maintained at a predetermined set ratio, thereby suitably controlling the super-heating degree of refrigerant discharged from the compressor  1 . After the rotation position of the valve body  130   a  is set, the valve body  130   a  is fixed to the upper connection joint  117   d  so that its set rotation position is not changed. 
   (Sixth Embodiment) 
   In the above-described fifth embodiment, the inlet joint  24 , the gas-refrigerant bypass passage  10  (the first communication hole  117   i , the lower refrigerant passage  117   g  and the throttle hole  117   j ) and the control valve  130  are provided in the condenser  2 . However, in the sixth embodiment, the inlet joint  24 , the gas-refrigerant bypass passage  10  and the control valve  130  are provided in the gas-liquid separator  7 , as shown in  FIGS. 12 ,  13 . In the sixth embodiment, the parts similar to those of the above-described fifth embodiment are indicated by the same reference numbers, and detail description thereof is omitted. 
   In the gas-liquid separator  7 , the tank body  170  has a circular upper opening  170   a  at its upper wall portion, and a cylindrical projection  24   a  of the inlet joint  24  is fitted into the upper opening  170   a  of the tank body  170 . An O-ring  24   b  as an elastic seal member is attached to an outer peripheral ditch of the cylindrical projection  24   a , so that the clearance between the cylindrical projection  24   a  and an inner peripheral surface of the upper opening  170   a  is air-tightly sealed. The inlet joint  24  is fixed to the upper wall portion of the tank body  170  by using bolts (not shown). The inlet joint  24  has a through passage hole  24   c  provided in an axial direction of the cylindrical projection  24   a  (in the up-down direction), and gas refrigerant discharged from the compressor  1  is circulated into an inner space of the upper opening  170   a  through the passage hole  24   c.    
   A ring plate portion  170   b  protruding to an inner space of the upper opening  170   a  is formed at a position lower than a top end surface of the upper opening  170   a  by a predetermined dimension. The ring plate portion  170   b  has a through hole at its center area, so as to form the gas-refrigerant bypass passage  10 . The gas refrigerant discharged from the compressor  1  flows into the upper opening  170   a . A part of the gas refrigerant flowing into the upper opening  170   a  is directly introduced into the circular inner space (gas-liquid separating space)  173  through the gas-refrigerant bypass passage  10 . The amount of gas refrigerant introduced into the circular inner space  173  is restricted by a passage area (hole opening area) of the gas-refrigerant bypass passage  10 . 
   As shown in  FIG. 13 , the control valve  130  is disposed in the gas-refrigerant bypass passage  10 . The control valve  130  include the valve body  130   a  having a rotary structure, and the valve body  130   a  has a through hole  130   d  provided in its radial direction. The ring plate portion  170   b  has a circular joint hole  170   c  extending in a direction perpendicular to the refrigerant flow direction (up-down direction) of the gas-refrigerant bypass passage  10 . The circular valve body  130   a  is fitted in the circular joint hole  170   c  to be rotatable in a direction indicated by C in  FIG. 13 . A rotation shaft (not shown) is integrated to an end of the valve body  130   a  in its axial direction (in a perpendicular direction of the paper surface of  FIG. 13 ), and is projected outside of the tank body  170 . The valve body  130   a  is rotated by operation from an outside of the tank body  170  through the rotation shaft. An elastic seal member such as an O-ring is disposed between the joint hole portion of the tank body  170  and the rotation shaft to seal therebetween. 
   Cylindrical projections  170   e ,  170   f  are integrated to an upper sidewall  170   d  of the tank body  170  at upper and lower sides (upstream and downstream sides) of the gas-refrigerant bypass passage  10 , respectively. The upper cylindrical projection  170   e  has therein a through hole for defining a gas-refrigerant condensing passage  178 . The gas refrigerant flowing into the upper opening  170   a  is distributed into the gas-refrigerant condensing passage  178  and the gas-refrigerant bypass passage  10 . In the sixth embodiment, an amount of gas refrigerant distributed into the gas-refrigerant bypass passage  10  is set larger than that distributed into the gas-refrigerant condensing passage  178 . 
   The lower cylindrical projection  170   f  also has therein a through hole for defining the liquid-refrigerant introduction passage  14 . All of refrigerant (liquid refrigerant) condensed in the first heat-exchanging portion  5  of the condenser  2  is introduced into a gas-liquid mixing area  173   a  through the liquid-refrigerant introduction passage  14 . The gas-liquid mixing area  173   a  is located directly below the gas-refrigerant bypass passage  10  in the inner space  173  of the tank body  170 . The gas-liquid mixing area  173   a  corresponds to the upper refrigerant passage  117   h  for forming the gas-liquid mixing portion in the fifth embodiment. O-rings  170   g ,  170   h  as elastic seal members are attached to outer circumferential ditches of both cylindrical projections  170   e ,  170   f , respectively. 
   A connection joint  117   p  is made of metal such as aluminum, and is brazed to the left header tank  117  of the condenser  2 . The connection joint  117   p  has circular passage holes  117   q ,  117   r . The cylindrical projections  170   e ,  170   f  of the tank body  170  are fitted in the circular passage holes  117   q ,  117   r . The O-ring  170   g  is provided to seal the clearance between the passage hole  117   q  of the connection joint  117   p  and the cylindrical projection  170   e , and the O-ring  170   h  is provided to seal the clearance between the passage hole  117   r  and the cylindrical projection  170   f . The tank body  170  is fixed to the connection joint  117   p  by bolts (not shown). The connection joint  117   p  includes cylindrical joint projections  117   s ,  117   t  corresponding to the refrigerant holes  117   q ,  117   r , respectively, in the left header tank  117 . The connection joint  117   p  is connected to the left header tank  117  while joint projections  117   s ,  117   t  are fitted in joint holes of the left header tank  117 . 
   In this way, the upper space  117   a  of the left header tank  117  communicates with the gas-refrigerant condensing passage  178  of the gas-liquid separator  7  through the upper passage hole  117   q  of the connection joint  117   p . The intermediate space  117   b  of the left header tank  117  communicates with the liquid-refrigerant introduction passage  14  of the gas-liquid separator  7  through the lower passage hole  117   r  of the connection joint  117   p . Accordingly, a part of the gas refrigerant introduced into the upper opening  170   a  of the gas-liquid separator  7  flows from the upper passage hole  117   q  into the upper space  117   a  of the left header tank  117  through the gas-refrigerant condensing passage  178 . Further, the condensed refrigerant (liquid refrigerant) in the intermediate space  117   b  of the left header tank  117  is circulated into the gas-liquid mixing area  173   a  through the lower passage hole  117   r  and the liquid-refrigerant introduction passage  14 . That is, the refrigerant is U-turned in the first heat-exchanging portion  5  as indicated by the arrow Fb′ in  FIG. 12 . 
   A return inlet joint  23 , for forming an inlet of refrigerant returned from the gas-liquid separator  7 , is connected to the left header tank  117  at a position corresponding to the lower space  117   c . The return inlet joint  23  is connected to a bottom connection joint  179  of the gas-liquid separator  7  through a connection pipe  23   a . The connection joint  179  is liquid-tightly fixed into a center hole  172   a  provided in the lower cover  172  through an O-ring as an elastic seal member. The center hole  172   a  corresponds to the refrigerant outlet passage in the fifth embodiment. On the other hand, a lower end of the pipe member  176  is fixed into and supported by the center hole  172   a  of the lower cover  172 . In this way, the lower end of the inner passage of the pipe member  176  communicates with a passage hole  179   a  of the connection joint  179 . The upper end of the pipe member  176  is located much higher than the liquid surface B of the liquid refrigerant stored in the gas-liquid separator  7 . 
   The mixed refrigerant in the gas-liquid mixing area  173   a  is separated into gas refrigerant and liquid refrigerant by using the centrifugal force of the turn flow A. The separated liquid refrigerant is stored in the inner space  173  of the gas-liquid separator  7  at the lower side, and the separated gas refrigerant is stored above the liquid refrigerant in the gas-liquid separator  7 . The gas refrigerant and the liquid refrigerant in the gas-liquid separator  7  are introduced into the pipe member  176  from the gas return opening  176   a  and the liquid return opening  176   b , respectively. Then, the gas refrigerant and the liquid refrigerant in the pipe member  176  flows into the lower space  117   c  of the left header tank  117  through the connection joint  179 , the connection pipe  23   a  and the return inlet joint  23 . 
   That is, in the sixth embodiment, the inlet joint  24  is disposed on the gas-liquid separator  7 , and the distribution mechanism for distributing the discharged gas refrigerant into the gas-liquid separator  7  and the first heat-exchanging portion  5  is also disposed in the gas-liquid separator  7 . Specifically, in the single state of the condenser  2  after a brazing process is finished before the gas-liquid separator  7  is attached to the condenser  2 , as described in the fifth embodiment, the refrigerant pressure P 1  at the inlet of the first heat-exchanging portion  5  and the refrigerant pressure P 2  at the outlet thereof are detected. Then, the pressure loss ΔP (P 1 –P 2 ) in the first heat-exchanging portion  5  is calculated based on detected pressure P 1  and detected pressure P 2 . The set value (i.e., rotation amount from the entirely closed position) of the valve body  130   a  of the control valve  130  is determined based on the pressure loss ΔP, and the valve body  130   a  is rotated to the set value. 
   Therefore, the ratio between the gas-refrigerant bypass amount and the liquid refrigerant amount flowing into the gas-liquid separator  7  can be maintained at the predetermined ratio without being affected by the dimension variation in the manufacturing and the dimension difference due to the solder invasion and the like. Thus, the super-heating degree of refrigerant can be suitably controlled in the refrigerant cycle system. Further, in the first to fifth embodiments, since the gas-refrigerant bypass passage  10  is provided in the condenser  2  at the connection joint  117   d , a solder (i.e., brazing material) may be invaded into the gas-refrigerant bypass passage  10  when the condenser  2  is integrally brazed. However, in the sixth embodiment, since the gas-refrigerant bypass passage  10  is provided in the gas-liquid separator  7 , the brazing material is prevented from being invaded into the gas-refrigerant bypass passage  10  in the brazing of the condenser  2 , and it can prevent the passage area of the gas-refrigerant bypass passage  10  from being reduced. 
   (Seventh Embodiment) 
   The seventh embodiment of the present invention will be now described with reference to  FIGS. 14 and 15 . In the seventh embodiment, the parts similar to those of the above-described fifth and sixth embodiments are indicated by the same reference numbers, and detail description thereof is omitted. As shown in  FIGS. 14 ,  15 , in the seventh embodiment, the valve body  130  of the sixth embodiment is not provided in the ring plate portion  170   b . Specifically, the ring plate portion  170   b  has a very small hole for defining the gas-refrigerant bypass passage  10 . The ring plate portion  170   b  can be integrated to the tank body  170  by die casting and the like, and the ring plate portion  170   b  is finely machined to provide the very small hole for forming the gas-refrigerant bypass passage  10 . 
   A part of the gas refrigerant, flowing into the upper opening  170   a , is introduced directly into a gas-liquid separating space  205  through the gas-refrigerant bypass passage (very small hole)  10 . An amount of the gas refrigerant flowing into the gas-liquid separating space  205  is set by the passage area (opening area of the very small hole) of the gas-refrigerant bypass passage  10 . Therefore, the distribution ratio of the gas refrigerant can be set by setting the passage area ratio between the gas-refrigerant bypass passage  10  and the gas-refrigerant condensing passage  178 . In the seventh embodiment, the distribution amount of gas refrigerant into the gas-refrigerant bypass passage  10  is set larger than that into the gas-refrigerant condensing passage  178 . 
   The tank body  170  of the gas-liquid separator  7  has a turn passage  230  in the gas-liquid separating space  205 , and refrigerant flows downward along the turn flow A in the turn passage  230 . A guide plate  231  is provided to prevent refrigerant from directly flowing downward from the gas-liquid mixing area  173   a  along the circular inner wall surface of the tank body  170 . Because the guide plate  231  is provided, the generation performance of the turn flow A of refrigerant can be improved. Further, the components of the gas-liquid separator  7  such as the pipe member  176  and the desiccant  177  can be attached into and detached from the tank body  170  by removing the lower cover  172  from the tank body  170 . 
   As in the sixth embodiment, a distribution passage structure, for distributing the gas refrigerant into the tank body  170  of the gas-liquid separator  7  and the first heat-exchanging portion  5 , is disposed in the gas-liquid separator  7 . Because the distribution passage structure is not required to be provided in the header tank  117  of the condenser  2 , a refrigerant passage structure of the header tank  117  of the condenser  2  can be simplified, thereby reducing its production cost. Further, a passage area of the gas-refrigerant bypass passage  10  can be readily changed in the tank body  170  of the gas-liquid separator  7  without changing the structure of the condenser  2 . Furthermore, as in the sixth embodiment, since the gas-refrigerant bypass passage  10  is provided in the tank body  70 , the gas-refrigerant bypass passage  10  is not adversely affected due to the solder invasion when the condenser portion of the condenser  2  is brazed. 
   Since the gas-refrigerant bypass passage  10  can be visually examined directly from the upper opening  170   a  of the tank body  170 , clogging abnormality of the gas-refrigerant bypass passage  10  can be readily found, thereby preventing a defective product from being delivered. Further, as in the first embodiment, the passage diameter of the gas-refrigerant bypass passage  10  can be increased to a relatively large diameter (e.g., Ø5.5 mm), thereby reducing the affecting degree of the dimension variations of the gas-refrigerant bypass passage  10  in the manufacturing. 
   (Eighth Embodiment) 
   In the above-described first to seventh embodiments, all of the condensed refrigerant (liquid refrigerant) after passing through the first heat-exchanging portion  5  is introduced into the gas-liquid separator  7 . However, in the eighth embodiment, a part of the condensed refrigerant after passing through the first heat-exchanging portion  5  is introduced into the gas-liquid separator  7 , and the other part thereof is introduced directly into the second heat-exchanging portion  6 . As shown in  FIG. 16 , the partition plate  20  is disposed in the right header tank  18  at a position lower than the arrangement position of the second partition plate  119   b  disposed in the left header tank  117 . 
   Therefore, in the eighth embodiment, a flow of the refrigerant after passing through the flat tubes  15  at the upper portion of the first heat-exchanging portion  5  is branched into two streams. Specifically, an about half of the refrigerant introduced into the upper space  117   a  of the left header tank  117  passes through the flat tubes  15  at a lower portion of the first heat-exchanging portion  5  as indicated by the arrow Fb′ in  FIG. 16 , and is condensed therein. The condensed refrigerant (liquid refrigerant) flows into the gas-liquid separator  7  through the intermediate space  117   b  of the left header tank  117  and the connection joint  117   p . On the other hand, the other part of the refrigerant introduced into the upper space  117   a  flows into the lower space  117   c  of the left header tank  117  as indicated by the arrow Fb″ in  FIG. 16  after passing through the flat tubes  15  in an upper area of the second heat-exchanging portion  6  upper than the partition wall  20 . The liquid refrigerant flowing into the lower space  117   c  of the left header tank  117  as indicated by the arrow Fb″ in  FIG. 6  is mixed with refrigerant introduced from the return inlet joint  23  therein. The mixed refrigerant in the lower space  117   c  passes through the flat tubes  15  at the lower area of the second heat-exchanging portion  6  as indicated by the arrow Fg′, and is super-cooled therein. 
   In the eighth embodiment, only a part of the refrigerant condensed in the first heat-exchanging portion  5  is introduced into the gas-liquid separator  7 . Therefore, the gas refrigerant amount distributed from the gas-refrigerant condensing passage  178  into the first heat-exchanging portion  5  is set larger than the gas refrigerant amount distributed into the gas-liquid separator  7  through the gas-refrigerant bypass passage  10 . 
   In the eighth embodiment, a cup-shaped guide plate  210  is disposed on an upper end of the pipe member  176  in place of the guide plate  231  described in the seventh embodiment, thereby increasing the gas-liquid separating performance. Liquid refrigerant drops from an outer peripheral portion of the guide plate  210 , and only gas refrigerant stored in the inner space  205  at an upper side is sucked into the gas return opening  176   a  of the pipe member  176 . In the eighth embodiment, the other parts are similar to those of the above-described seventh embodiment. 
   (Ninth Embodiment) 
   In the sixth to eight embodiments, the inlet joint  24  is disposed in the gas-liquid separator  7 , and both of the gas-refrigerant condensing passage  178  and the gas-refrigerant bypass passage  10  are provided in the tank body  170  of the gas-liquid separator  7 . However, in the ninth embodiment, as shown in  FIGS. 17 ,  18 , a gas-refrigerant condensing passage  178   a  and the gas-refrigerant bypass passage  10  are provided in the inlet joint  24 . Therefore, an axial dimension of the cylindrical projection  24   a  of the inlet joint  24  is made larger than that in the sixth to eighth embodiments. In this way, a bottom end of the cylindrical projection  24   a  is located around the liquid-refrigerant introduction passage  14 , that is, at a portion directly above the gas-liquid mixing area  173   a.    
   Further, the inlet joint  24  is provided with the gas-refrigerant bypass passage  10  around the bottom end of the passage hole  24   c . A passage area (passage diameter) of the gas-refrigerant bypass passage  110  is set smaller by a predetermined area than that of the passage hole  24   c . A through hole used as the gas-refrigerant condensing passage  178   a  is provided in an outer peripheral surface of the cylindrical projection  24   a  at a position facing the upper cylindrical projection  170   e  of the tank body  170 . The gas-refrigerant condensing passage  178   a  of the inlet joint  24  communicates with the upper space  117   a  of the left header tank  117  through the gas-refrigerant condensing passage  178  of the tank body  170  and the passage hole  117   q  of the connection joint  117   p . Here, the passage area (passage diameter) of the gas-refrigerant condensing passage  178   a  of the inlet joint  24  and the gas-refrigerant condensing passage  178  of the tank body  170  is made smaller than that of the passage hole  117   q  of the connection joint  117   p . Therefore, the gas-refrigerant distribution amount into the first heat-exchanging portion  5  can be set by setting the passage area (passage diameter) of the gas-refrigerant condensing passages  178 ,  178   a  without receiving an affection due to the solder invasion. 
   The cylindrical projection  24   a  has an outer peripheral ditch  24   e  at its bottom end side with respect to the gas-refrigerant condensing passage  178   a , and an O-ring  24   f  as an elastic seal member is attached to the outer peripheral ditch  24   e . The O-ring  24   f  can prevent the discharged gas refrigerant in the gas-refrigerant condensing passage  178   a  from flowing into the gas-liquid mixing area  173   a  through a clearance between the outer peripheral surface of the cylindrical projection  24   a  and the inner peripheral surface of the tank body  170 . 
   In the ninth embodiment, all of condensed refrigerant from the first heat exchanging portion  5  is introduced into the gas-liquid separator  7 . In the ninth embodiment, the other parts are similar to those of the above-described seventh embodiment. 
   Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. 
   For example, in the above-described fifth to seventh and ninth embodiments, a part of liquid refrigerant condensed in the first heat-exchanging portion may be introduced into the gas-liquid separator  7  while the other part thereof is introduced into the second heat-exchanging portion  6 , similarly to the eighth embodiment. 
   Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.