Patent Publication Number: US-6698235-B2

Title: Refrigerant cycle system having discharge function of gas refrigerant in receiver

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based on Japanese Patent Application No. 2001-283608 filed on Sep. 18, 2001, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a refrigerant cycle system with an improved refrigerant-sealing performance. More particularly, the present invention relates to a discharge structure of gas refrigerant in a receiver of the refrigerant cycle system, which separates refrigerant from a refrigerant condenser into gas refrigerant and liquid refrigerant, and stores the liquid refrigerant therein. The present invention is suitably applied to a vehicle air conditioner. 
     2. Description of Related Art 
     In a conventional refrigerant cycle for a vehicle air conditioner, when heat from an engine compartment is transmitted to a receiver, liquid refrigerant stored within the receiver is boiled, and gas pressure within the receiver is increased. Therefore, a liquid refrigerant surface in the receiver becomes lower, and liquid refrigerant is discharged from the receiver to a downstream side. Accordingly, the liquid refrigerant stays in a condenser, high-pressure side refrigerant pressure is increased in the refrigerant cycle, and power consumed in a compressor is increased. 
     To overcome this problem, U.S. Pat. No. 6,374,632 proposes a refrigerant cycle system in which liquid refrigerant from a condenser flows into a receiver from upper and lower sides in the receiver. That is, in this refrigerant cycle system, an upper space of the receiver is cooled by latent heat of liquid refrigerant flowing from the upper side. However, a desiccant for adsorbing water contained in refrigerant is generally disposed within the receiver, and the refrigerant flow from the upper side in the receiver is restricted by the desiccant. As a result, the upper space of the receiver may not be sufficiently cooled using the liquid refrigerant introduced from the upper side. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing problems, it is an object of the present invention to improve refrigerant sealing performance in a refrigerant cycle system. 
     It is an another object of the present invention to provide a refrigerant cycle system with a receiver, which prevents an increase of a gas pressure in the receiver even when the heat is transmitted into the receiver from an outside. 
     According to the present invention, a refrigerant cycle system includes a first refrigerant passage through which refrigerant after passing through a condensation portion of a condenser flows into a receiver, a second refrigerant passage through which liquid refrigerant stored at a lower side in the receiver flows outside the receiver, and a third refrigerant passage having two end portions with a predetermined pressure difference, through which gas refrigerant staying at an upper side in the receiver is discharged to a downstream side of the receiver. Accordingly, even when heat is transmitted into the receiver from an outside and liquid refrigerant in the receiver is boiled, because gas refrigerant at the upper side in the receiver is discharged outside the receiver through the third refrigerant passage, it can restrict the gas pressure in the receiver from being increased. As a result, it can prevent a liquid refrigerant surface in the receiver from being lowered due to an increase of the gas pressure in the receiver. That is, it can prevent refrigerant from over-flowing from the receiver toward the condenser. Therefore, refrigerant-sealing performance in the refrigerant cycle system can be improved, and COP of the refrigerant cycle system can be improved. 
     Preferably, the condenser includes a core portion at least including the condensation portion, and a header tank extending in the up-down direction to communicate with tubes of the core portion. Further, the receiver is integrated with the header tank, and each of the first and second refrigerant passages is a communication hole penetrating through the header tank and the receiver. Accordingly, the present invention can be effectively used for a refrigerant cycle system having a receiver-integrated condenser. In this case, the first refrigerant passage and the second refrigerant passage can be readily provided. 
     Preferably, the third refrigerant passage can be defined by a gas bypass pipe connected to the receiver from an outside of the receiver. Alternatively, a connection plate member can be inserted between the header tank and the receiver, and the third refrigerant passage is provided in the connection plate member. Alternatively, the third refrigerant passage can be provided in an approximately cylindrical body portion of the receiver while the body portion is integrally formed by punching or drawing. Accordingly, third refrigerant passage can be readily formed, and the gas refrigerant at the upper side in the receiver can be readily discharged. 
     Preferably, the second refrigerant passage is provided to generate a pressure loss therein, the third refrigerant passage has an outlet from which the gas refrigerant introduced in the third refrigerant passage from the upper side in the receiver is discharged, and the outlet of the third refrigerant passage is provided in the second refrigerant passage or at a downstream side of the second refrigerant passage. In this case, the third refrigerant passage readily has the predetermined pressure difference at the two end portions, and the gas refrigerant in the receiver can be effectively discharged. 
    
    
     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 partially-sectional schematic diagram showing a refrigerant cycle system according to a first preferred embodiment of the present invention; 
     FIG. 2 is a schematic perspective view showing a main portion of a receiver-integrated refrigerant condenser of the refrigerant cycle system according to the first embodiment; 
     FIG. 3 is a graph showing a relationship between a super-cooling temperature (degree) of refrigerant at an outlet of a super-cooling portion and a refrigerant amount sealed in the refrigerant cycle system, according to the first embodiment; 
     FIG. 4 is a graph obtained by experiments, showing a relationship between a gas-bypass flow amount, a refrigerant amount circulating in the refrigerant cycle system, and a ratio of a hole area of the second communication hole to a gas bypass sectional area, according to the first embodiment; 
     FIG. 5 is a schematic sectional view showing a main portion of a receiver-integrated refrigerant condenser of a refrigerant cycle system according to a second preferred embodiment of the present invention; 
     FIG. 6A is a sectional view and FIG. 6B is a front view, each showing a main portion of a receiver-integrated refrigerant condenser of a refrigerant cycle system according to a third preferred embodiment of the present invention; 
     FIG. 7A is a schematic sectional view showing a receiver-integrated refrigerant condenser of a refrigerant cycle system according to a fourth preferred embodiment of the present invention, and FIG. 7B is a cross-sectional view taken along line VIIB—VIIB in FIG. 7A; 
     FIG. 8A is a schematic sectional view showing a receiver-integrated refrigerant condenser of a refrigerant cycle system according to a fifth preferred embodiment of the present invention, and FIG. 8B is a cross-sectional view taken along line VIIIB—VIIIB in FIG. 8A; 
     FIG. 9A is a schematic sectional view showing a receiver-integrated refrigerant condenser of a refrigerant cycle system according to the sixth preferred embodiment of the present invention, and FIG. 9B is a cross-sectional view taken along line IXB—IXB in FIG. 9A; 
     FIG. 10A is a sectional view showing a main portion of a receiver-integrated condenser according to a seventh preferred embodiment of the present invention, FIG. 10B is a cross-sectional view taken along line XB—XB in FIG. 10A, and FIG. 10C is a cross-sectional view taken along line XC—XC in FIG. 10A; and 
     FIG. 11A is a vertical sectional view and FIG. 11B is a transverse sectional view, each showing a main structure of a receiver-integrated refrigerant condenser, according to an eighth preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will be described hereinafter with reference to the accompanying drawings. 
     A first preferred embodiment of the present invention will be now described with reference to FIGS. 1-4. In the first embodiment, the present invention is typically applied to a refrigerant cycle system for a vehicle air conditioner. As shown in FIG. 1, the refrigerant cycle system of the vehicle air conditioner includes a refrigerant compressor  1 , a receiver-integrated refrigerant condenser  2 , a sight glass  3 , an expansion valve  4 , and a refrigerant evaporator  5 . All the components of the refrigerant cycle system are serially connected by a metal pipe or a rubber pipe to form a closed circuit. 
     The compressor  1  is connected to an engine disposed within an engine compartment through a belt and an electromagnetic clutch  1   a . When the rotation power of the engine is transmitted to the compressor  1  through the electromagnetic clutch  1   a , the compressor  1  compresses gas refrigerant sucked therein from the evaporator  5  and then discharges high-pressure high-temperature gas refrigerant toward an inlet joint  26  of the receiver-integrated refrigerant condenser  2 . 
     The sight glass  3  is connected to a downstream refrigerant side of an outlet joint  27  of the receiver-integrated refrigerant condenser  2 . The sight glass  3  is used as a refrigerant amount monitoring unit for monitoring the amount of refrigerant sealed in the refrigerant cycle system to check for the over or short supply by observing gas-liquid state. The sight glass  3  has a peephole  3   a  air-tightly sealed by a melted glass. When bubbles are found from the peephole  3   a , it is determined that the amount of refrigerant is short-supplied. On the other hand, when bubbles are not founded, it is determined that refrigerant is properly supplied. 
     Refrigerant from the receiver-integrated refrigerant condenser  2  is decompressed in the expansion valve  4 , so that low-temperature low-pressure refrigerant can be obtained. The evaporator  5  is a cooling unit for cooling air blown into a passenger compartment. That is, in the evaporator  5 , refrigerant from the expansion valve  4  is evaporated by absorbing heat from air, so that air passing through the evaporator  5  is cooled. 
     Next, the structure of the receiver-integrated refrigerant condenser  2  will be now described. The receiver-integrated refrigerant condenser  2  includes a pair of first and second header tanks  21 ,  22  each of which extends in an up-down direction (i.e., vertical direction) and is formed into approximately cylindrically. A core portion  23  is disposed between the first and second header tanks  21 ,  22 . 
     The core portion  23  includes plural flat tubes  24  through which refrigerant flows horizontally between the first and second header tanks  21 ,  22 , and plural corrugated fins  25  each of which is disposed between adjacent flat tubes  24 . Each one side end of the flat tubes  24  communicates with the first header tank  21 , and each the other side end of the flat tubes  24  communicates with the second header tank  22 . The inlet joint  26  is connected to the first header tank  21  at an upper side, and the outlet joint  27  is connected to the first header tank  21  at a lower side. 
     In the first embodiment, a first separator  28  is disposed within the first header tank  21  at a lower side position, and a second separator  29  is disposed within the second header tank  22  at the same height position as the first separator  28 . Thus, an inner space of the first header tank  21  is partitioned into upper and lower spaces  21   a ,  21   b  in the up-down direction by the first separator  28 , and an inner space of the second header tank  22  is also partitioned into upper and lower spaces  22   a ,  22   b  in the up-down direction by the second separators  29 . Accordingly, refrigerant introduced into the upper space  21   a  of the first header tank  21  from the inlet joint  26  passes through the flat tubes  24  as shown by the arrow “a” in FIG. 1, and flows into the upper space  22   a  of the second header tank  22 . 
     A condensation portion  23   a  is constructed by an upper portion in the core portion  23  of the receiver-integrated refrigerant condenser  2 , positioned upper than the first and second separators  28 ,  29 . In the condensation portion  23   a  of the core portion  23 , air blown by a cooling fan (not shown) is heat-exchanged with refrigerant flowing through the flat tubes  24  to cool the refrigerant. 
     A receiving unit  31  is formed integrally with the second header tank  22  in the receiver-integrated refrigerant condenser  2 . Gas refrigerant and liquid refrigerant are separated in the receiving unit  31 , and liquid refrigerant is stored in the receiving unit  31 . The receiving unit  31  is formed into an approximate cylindrical shape, and is connected to an outer surface of the second header tank  22  at a side opposite to the core portion  23 . The receiving unit  31  has a height slightly lower than that of the second header tank  22 . Components of the receiver-integrated refrigerant condenser  2  including the receiving unit  31  are formed from an aluminum material, and are assembled integrally by brazing. 
     A super-cooling portion  23   b  is constructed by a lower portion in the core portion  23  of the receiver-integrated refrigerant condenser  2 , positioned lower than the first and second separators  28 ,  29 . In the super-cooling portion  23   b  of the core portion  23 , liquid refrigerant separated in the receiving unit  31  is super-cooled by performing a heat exchange with outside air. 
     Next, a communication structure communicating between an inner space of the receiving unit  31  and an inner space of the second header tank  22  will be now described. As shown in FIG. 2, a first communication hole  32  (first refrigerant passage) is provided in a wall surface between the second header tank  22  and the receiving unit  31  to penetrate through the wall surface at a position slightly upper than the second separator  29  in the second header tank  22 , so that the upper space  22   a  of the second header tank  22  communicates with the receiving unit  31  through the first communication hole  32 . A second communication hole  33  (second refrigerant passage) is provided in the wall surface between the second header tank  22  and the receiving unit  31  to penetrate through the wall surface at a position lower than the second separator  29 , so that the inner space at a lower side in the receiving unit  31  communicates with the lower space  22   b  in the second header tank  22  through the second communication hole  33 . 
     Each of the first and second communication holes  32 ,  33  is formed into a rectangular shape, for example. Refrigerant passing through the condensation portion  23   a  of the core portion  23  flows into the lower side space in the receiving unit  31  through the first communication hole  32 , and liquid refrigerant stored in the lower side within the receiving unit  31  flows into the lower space  22   b  in the second header tank  22  through the second communication hole  33 . 
     Further, a gas bypass pipe  34  defining a gas bypass passage (third refrigerant passage) is connected between the receiving unit  31  and the second header tank  22 . In the first embodiment, gas refrigerant staying in the upper side within the receiving unit  31  can be discharged to a downstream side of the receiving unit  31  from the receiving unit  31  through the gas bypass pipe  34 . For example, a thin pipe having an inner diameter of φ2 mm can be used as the gas bypass pipe  34 . One end (upper end) of the gas bypass pipe  34  communicates with the upper side space within the receiving unit  31 , and the other end (lower end) of the gas bypass pipe  34  communicates with the lower space  22   b  of the second header tank  22  at a position slightly lower than the second separator  29 . That is, the other end (outlet portion) of the gas bypass pipe  34  communicates with the lower space  22   b  within the second header tank  22  at a position directly after the second communication hole  33 . 
     For obtaining a gas-refrigerant discharge function using the gas bypass pipe  34 , it is necessary to have a predetermined pressure difference between both ends of the gas bypass pipe  34 . Specifically, an opening area of the second communication hole  33  is set at an area corresponding to φ3 mm. The opening area of second communication hole  33  is greatly smaller than a pipe sectional area of a high-pressure liquid refrigerant pipe  27   a  (see FIG. 1) connected to the outlet joint  27  of the refrigerant condenser  2 . Generally, the inner diameter of the high-pressure liquid refrigerant pipe  27   a  is φ6 mm. 
     In the first embodiment, the second communication hole  33  is provided to generate a pressure loss therein. Accordingly, the pressure loss is caused in a main flow (shown by the arrow “b”) of refrigerant passing through the second communication hole  33 . Thus, the second communication hole  33  is used as a pressure generation portion (throttle portion) for generating the pressure loss. Therefore, the pressure at the other end of the gas bypass pipe  34 , positioned at a direct downstream side of the second communication hole  33  is decreased as compared with the pressure at the one end (upper end) of the gas bypass pipe  34 , opened at a top side within the receiving unit  31 . As a result, gas refrigerant in the upper side within the receiving unit  31  can flow into a downstream side of the second communication hole  33  through the gas bypass pipe  34 . 
     It is unnecessary to generate a pressure loss in the first communication hole  32 . Therefore, the opening area of the first communication hole  33  can be made sufficiently larger. For example, the opening area of the first communication hole  33  is set at an area corresponding to φ10 mm. 
     On the other hand, a cylindrical body portion (tank member) of the receiving unit  31  is formed approximately cylindrically by bending and connecting a single plate. A lower end of the cylindrical body portion of the receiving unit  31  is closed by an installation pedestal.  35 . The installation pedestal  35  is air-tightly detachably fixed to the body portion of the receiving unit  31  through a seal member by using screwing means. A filter  36  for removing dust contained in refrigerant is integrally formed on an upper side of the installation pedestal  35 . The filter  36  is formed by a network structure having a cylindrical shape. A desiccant  37  for absorbing water contained in refrigerant is disposed at an upper side of the filter  36 . The desiccant  37  is constructed by a grained desiccant contained in a bag member in which refrigerant can pass. 
     Liquid refrigerant in the lower side of the receiving unit  31  flows into an inner side of the network filter  36  after contacting the desiccant  37 , as shown by the arrow “b” in FIGS. 1 and 2. Thereafter, the liquid refrigerant from the filter  36  passes through the second communication hole  33 , and flows into the lower space  22   b  of the second header tank  22 . 
     Accordingly, in the first embodiment of the present invention, the receiver-integrated refrigerant condenser  2  is constructed by the condensation portion  23   a , the receiving unit  31  and the super-cooling portion  23   b  in this order in the refrigerant flow direction. In a normal refrigerant-sealing state, the gas-liquid interface surface within the receiving unit  31  is placed at an intermediate height position between the first communication hole  32  and a top end surface of the receiving unit  31 . 
     The receiver-integrated refrigerant condenser  2  is disposed at a most front portion within the engine compartment on a front side of a radiator, and both of the refrigerant condenser  2  and the radiator are cooled by a common cooling fan. 
     Next, operation of the refrigerant cycle system will be described. When operation of the vehicle air conditioner starts and the electromagnetic clutch  1   a  is turned on, rotation power of the engine is transmitted to the compressor  1  so that refrigerant is compressed and discharged by the compressor  1 . Thus, super-heating gas refrigerant discharged from the compressor  1  flows into the upper space  21   a  of the first header tank  21  of the refrigerant condenser  2  through the inlet joint  26 . Refrigerant in the upper space  21   a  of the first header tank  21  flows into the upper space  22   a  of the second header tank  22  after passing through the upper side tubes  24  in the condensation portion  23   a . While refrigerant flows through the tubes  24  in the condensation portion  23   a , refrigerant discharged from the compressor  1  is heat-exchanged with air passing through the condensation portion  23   a  to be cooled. Refrigerant flowing into the upper space  22   a  of the second header tank  22  is a super-cooled liquid refrigerant having some super-cooling degree, or a saturation liquid refrigerant including a part of gas refrigerant. Refrigerant flowing into the upper space  22   a  of the second header tank  22  flows into the lower side within the receiving unit  31  through the first communication hole  32  as shown by the arrow “b” in FIG.  1 . 
     Refrigerant is separated into gas refrigerant and liquid refrigerant in the receiving unit  31 , and the liquid refrigerant is stored therein. The liquid refrigerant at the lower side within the receiving unit  31  flows into the lower space  22   b  in the second header tank  22  through the second communication hole  33  as shown by the arrow “b”, and further flows through the tubes  24  in the super-cooling portion  23   b  from the lower space  22   b  of the second header tank  22 . 
     In the super-cooling portion  23   b , the liquid refrigerant is further cooled, and the super-cooled refrigerant is discharged to an outside of the condenser  2  from the outlet joint  27  after passing through the lower space  21   b  of the first header tank  21 . 
     The super-cooled liquid refrigerant passes through the sight glass  3 , and flows into the expansion valve  4 . The super-cooled refrigerant is decompressed in the expansion valve  4  to becomes in low-temperature low pressure gas-liquid refrigerant. Gas-liquid refrigerant from the expansion valve  4  is heat-exchanged with air in the evaporator  5 , so that air passing through the evaporator  5  is cooled by absorbing evaporation latent heat of refrigerant. Super-heating gas refrigerant evaporated in the evaporator  5  is sucked into the compressor  1  to be compressed again. 
     Next, refrigerant sealing performance (refrigerant receiving performance) of the refrigerant cycle system due to the gas bypass pipe  34  will be now described. When the receiver-integrated refrigerant condenser  2  is actually mounted on the vehicle, hot air in the engine compartment, after passing through the condenser  2  and the radiator, can be introduced into a front side of the condenser  2  in a vehicle idling, for example. In this case, heat in the engine compartment is readily transmitted to the receiving unit  31 . When the receiving unit  31  receives heat from the hot air in the engine compartment, liquid refrigerant within the receiving unit  31  is boiled, and gas refrigerant pressure in the receiving unit  31  is increased. Therefore, the liquid surface of the liquid refrigerant in the receiving unit  31  may be decreased. However, according to the first embodiment of the present invention, the upper-side gas refrigerant space within the receiving unit  31  communicates with the lower space  22   b  at a downstream side of the second communication hole  33  where the pressure loss is caused, through the gas bypass pipe  34 . Therefore, the pressure at the lower end of the gas bypass pipe  34  becomes lower than the pressure at the upper end of the gas bypass pipe  34 . Accordingly, gas refrigerant at the upper side in the receiving unit  31  can be discharged into the lower space  22   b  at the downstream side of the second communication hole  33 , through the gas bypass pipe  34 . Thus, even when the liquid refrigerant within the receiving unit  31  is boiled by receiving heat from the hot air in the engine compartment, it can restrict the gas refrigerant pressure within the receiving unit  31  from being increased. As a result, even when the receiving unit  31  receives heat from an outside, the liquid surface of the liquid refrigerant in the receiving unit  31  is not lowered, and liquid refrigerant can be effectively stored in the receiving unit  31 . Further, it can restrict refrigerant over-flowing from the receiving unit  31  toward the condenser  2 , thereby preventing an increase of the high-pressure side refrigerant pressure and an increase of power consumed in the compressor  1 . Therefore, the performance of cycle (COP) can be improved in the refrigerant cycle system. 
     The gas refrigerant from the gas bypass pipe  34  is cooled while passing through the tubes  24  in the super-cooling portion  23   b  from the lower space  22   b  in the second header tank  22 , and becomes in a super-cooling state. 
     The inventors of the present invention experimentally produce the condenser  2  (examples A and B) having the gas bypass pipe  34  and a comparison example C without the gas bypass pipe  34 , and compare the refrigerant sealing performance, as shown in FIG.  3 . FIG. 3 shows a relationship between the super-cooling degree of refrigerant at the outlet of the super-cooling portion  23   b  of the condenser  2  and a refrigerant amount sealed in the refrigerant cycle system, in the examples A, B and C. As a refrigerant sealing condition in FIG. 3, the temperature of cooling air flowing into an inlet of the condenser is set at 35° C., a flow rate of the cooling air flowing into the inlet of the condenser is set at 2.5 m/s, the temperature of air sucked into the evaporator  5  is at 30° C., the humidity of air sucked into the evaporator  5  is 50% RH, and the rotation speed of the compressor  1  is at 1500 rpm. Further, among the examples A and B of the present invention having the gas bypass pipe  34 , a flow amount of gas refrigerant flowing through the gas bypass path  34  is set at 5 cc/sec in the example A, and the flow amount of gas refrigerant flowing through the gas bypass path  34  is set at 3 cc/sec in the example B. On the contrary, the example C is a comparison example without having the gas bypass pipe  34 . 
     In the comparison example C without having the gas bypass pipe  34 , gas refrigerant at the upper side in the receiving unit  31  cannot be discharged from the receiving unit  31 . Therefore, liquid refrigerant cannot be effectively stored at the upper side in the receiving unit  31 . Accordingly, when the refrigerant sealing amount is increased in the refrigerant cycle system, the refrigerant amount over-flowing into the super-cooling portion is increased, and the super-cooling degree at the outlet of the super-cooling portion  23   b  is increased, as shown in FIG.  3 . As a result, in the comparison example C, the high-pressure side refrigerant pressure is increased, and the COP of the refrigerant cycle system is decreased. 
     However, in the examples A and B of the present invention, because the gas refrigerant at the upper side in the receiving unit  31  can be discharged to the downstream side of the second communication hole  33 , through the gas bypass pipe  34 , liquid refrigerant also can be stored at the upper side within the receiving unit  31 . Therefore, as shown in FIG. 3, in a predetermined refrigerant-amount range L, the super-cooling degree at the outlet of the super-cooling portion  23   b  can be made approximately constant, and the COP of the refrigerant cycle system can be improved. Further, when the flow amount of refrigerant in the gas bypass pipe  34  is increased as in the example A of the present invention, it can further restrict the super-cooling degree from being increased at the outlet of the super-cooling portion  23   b . According to experiments by the inventors of the present invention, when the flow amount of gas refrigerant in the gas bypass pipe  34  is set in a range of 3-5 cc/sec, the super-cooling degree at the outlet of the super-cooling portion  23   b  can be effectively restricted. 
     FIG. 4 shows a relationship between a refrigerant circulation amount in the refrigerant cycle system and a gas-bypass flow amount. In FIG. 4, examples D, E and F show the cases where the opening areas of the second communication holes  33  correspond to areas of φ4 mm, φ3 mm and φ2 mm, respectively. Further, the inner diameter of the gas bypass pipe  34  is set at 2 mm, in each of the examples D, E and F. As shown in FIG. 4, when the opening area of the second communication hole  33  is made smaller, the pressure loss caused in the second communication hole  33  is increased, thereby increasing the pressure difference between both the ends of the gas bypass pipe  34  and increasing the gas bypass flow amount. 
     A second preferred embodiment of the present invention will be now described with reference to FIG.  5 . In the above-described first embodiment of the present invention, the outlet of the gas bypass pipe  34  communicates with the lower space  22   b  of the second header tank  22  of the condenser  2 . However, in the second embodiment, as shown in FIG. 5, the outlet of the gas bypass pipe  34  is provided to communicate with the lower space  21   b  of the first header tank  21 . 
     According to the second embodiment of the present invention, because the pressure difference is generated between both the ends of the gas bypass pipe  34  due to the pressure loss in the super-cooling portion  23   b , it is unnecessary for the second communication hole  33  to be used as the pressure-loss generation portion. Accordingly, the opening area of the second communication hole  33  can be freely set. 
     In the second embodiment, because the super-cooling portion  23   b  is used as the pressure-loss generation portion, the outlet end of the gas bypass pipe  34  can be connected to the high-pressure liquid refrigerant pipe  27   a  (see FIG.  1 ). Alternatively, the outlet end of the gas bypass pipe  34  can be connected to a low-pressure side refrigerant passage (e.g., a downstream side of the expansion valve  4 ), through a suitable throttle. 
     A third preferred embodiment of the present invention will be now described with reference to FIGS. 6A and 6B. In the above-described first and second embodiments of the present invention, the gas bypass pipe  34  joined from an outside of the receiving unit  31  is used as a gas-refrigerant discharge unit for discharging the gas refrigerant at the upper side in the receiving unit  31  to an outside of the receiving unit  31 . However, in the third embodiment, the gas-refrigerant discharge unit is constructed by using a connection plate  40  that is used for temporally fixing the receiving unit  31  and the second header tank  22 . 
     As shown in FIGS. 6A and 6B, in the third embodiment of the present invention, the connection plate  40  is inserted between the receiving unit  31  and the second header tank  22 , to be connected to the receiving unit  31  and the second header tank  22  by a fastening member. Therefore, in an assembling step before a brazing of the receiver-integrated refrigerant condenser  2 , the connection plate  40  is used for temporally fixing the receiving unit  31  and the second header tank  22 . 
     As shown in FIG. 6B, the connection plate  40  is made of an aluminum alloy, and is formed into an elongated rectangular shape by pressing. In the pressing, the first communication hole  32  and the second communication hole  33  are opened in the connection plate  40 , and a gas bypass passage  41  (third refrigerant passage) extending in a longitudinal direction (i.e., vertical direction) of the connection plate  40  is provided in the connection plate  40 . A lower end portion of the gas bypass passage  41  is bent by a right angle to communicate with the second hole  33 . Further, an upper end of the gas bypass passage  41  is bent by a right angle to form a gas-refrigerant inlet portion  41   a . The gas bypass passage  41  is formed in the connection plate  40  by punching a plate surface of the connection plate  40 . 
     On the other hand, a gas-refrigerant introduction hole  42  is opened in a wall surface of the receiving unit  31 , contacting the connection plate  40 , at an upper end side. The connection plate  40  and the receiving unit  3  are temporally fixed so that the gas-refrigerant introduction hole  42  communicates with the gas-refrigerant inlet portion  41   a  of the connection plate  40 . After the brazing of the receiver-integrated refrigerant condenser  2  is finished, both front and back surfaces of the connection plate  40  are bonded to a flat surface of the receiving unit  31  and a flat surface of second header tank  22 . The gas bypass passage  41  is defined between the flat surface of the receiving unit  31  and the flat surface of the second header tank  22 . 
     According to the third embodiment of the present invention, the gas refrigerant at the upper side in the receiving unit  31  flows into the gas-refrigerant inlet portion  41   a  of the connection plate  40  from the gas-refrigerant introduction hole  42 , and flows through the gas bypass passage  41  downwardly. Thereafter, the has refrigerant in the gas bypass passage  41  flows into the lower space  22   b  of the second header tank  22  through the second communication hole  33  from the lower end portion (outlet portion) of the gas bypass passage  41 . 
     In the third embodiment, the gas bypass passage  41  corresponding to the gas bypass pipe  34  of the first embodiment is constructed using the connection plate  40  for temporally fixing the receiving unit  31  and the second header tank  22  of the receiver-integrated refrigerant condenser  2 . Accordingly, the gas-refrigerant discharge unit for discharging the gas refrigerant in the receiving unit  31  can be manufactured in low cost. In the third embodiment, other portions are similar to those of the above-described first embodiment. Therefore, in the third embodiment, the same advantage described in the first embodiment can be obtained. 
     A fourth preferred embodiment of the present invention will be now described with reference to FIGS. 7A and 7B. In the above-described third embodiment of the present invention, the lower end portion of the gas bypass passage  41  of the connection pipe  40  is directly communicated with the second communication hole  33 . However, in the fourth embodiment of the present invention, as shown in FIGS. 7A and 7B, the lower end portion (outlet portion) of the gas-refrigerant bypass passage  41  of the connection plate  40  is communicated with the lower space  22   b  of the second header tank  22  around the second communication hole  33 . That is, the lower end portion (outlet portion) of the gas-refrigerant bypass passage  41  of the connection plate  40  is communicated with the lower space  22   b  of the second header tank  22  at a downstream side of the second communication hole  33  in the refrigerant flow direction. Even in this case, the advantage described in the first embodiment can be obtained. 
     A fifth preferred embodiment of the present invention will be now described with reference to FIGS. 8A and 8B. In the fifth embodiment, two second separators  29   a ,  29   b  are provided in the second header tank  22  to have a predetermined distance therebetween in the up-down direction. A bypass chamber  22   c  is provided in the second header tank  22  between the two separators  29   a  and  29   b , and the lower end portion (outlet portion) of the gas bypass passage  41  of the connection plate  40  communicates with the bypass chamber  22   c . Further, the bypass chamber  22   c  is provided to communicate the lower space  21   b  of the first header tank  21  through the bypass tube  24   a  disposed between the condensation portion  23   a  and the super-cooling portion  23   b  in the core portion  23 . 
     According to the fifth embodiment of the present invention, a gas bypass path corresponding to the gas bypass pipe  34  described in the second embodiment is constructed by the gas bypass passage  41  of the connection plate  40 , the bypass chamber  22   c  and the bypass tube  24   a . Accordingly, similarly to the above-described second embodiment of the present invention, the second communication hole  33  can be formed to not generate the pressure loss. That is, the area of the second communication hole  33  can be arbitrarily changed. 
     In the fifth embodiment of the present invention, the bypass tube  24   a  can be formed into the same shape as the other tubes  24 . Alternatively, in the fifth embodiment, a passage sectional area of the bypass tube  24   a  can be formed larger than the other tubes  24 . In this case, the gas bypass amount through the bypass tube  24   a  can be increased. 
     A sixth preferred embodiment of the present invention will be now described with reference to FIGS. 9A and 9B. In the sixth embodiment, the two second separators  29   a ,  29   b  are disposed in the second header tank  22  so that the inner space of the second header tank  22  is separated into an upper space  22   a , a middle space  22   d  and a lower space  22   b , in the up-down direction of the second header tank  22 . 
     Further, the second communication hole  33  is communicated with the middle space  22   d  of the second header tank  22 , so that the liquid refrigerant at the lower side in the receiving unit  31  flows into the middle space  22   d , and passes through the tubes  24  at the upper side in the super-cooling portion  23   b . Further, in the sixth embodiment, the outlet joint  27  is provided to communicate with the lower space  22   b  in the second header tank  22 . Accordingly, liquid refrigerant at the lower side in the receiving unit  31  passes through the second communication hole  33 , passes through the tubes  24  at the upper portion in the super-cooling portion  23   b , and flows into the lower space  21   b  of the first header tank  21  to be U-turned in the lower space  21   b  of the first header tank  21  as shown by the arrow “f” in FIG.  9 A. Thereafter, the liquid refrigerant, after being U-turned in the lower space  21   b  of the first header tank  21 , passes through the tubes  24  at the lower side portion in the super-cooling portion, and flows into the lower space  22   b  of the second header tank  22  to be discharged from the outlet joint  27 . 
     On the other hand, the lower end portion (outlet portion) of the gas bypass passage  41  formed in the connection plate  40  communicates with the lower space  22   b  within the second header tank  22 . Therefore, the gas refrigerant at the upper side in the receiving unit  31  is discharged into the lower space  22   b  in the second header tank  22  through the gas bypass passage  41 . 
     According to the sixth embodiment of the present invention, the pressure difference can be caused between both the ends of the gas bypass passage  41  by the pressure loss in the U-turn passage in the super-cooling portion  23   b . Therefore, it is unnecessary to form the pressure loss function in the second communication hole  33 . 
     A seventh preferred embodiment of the present invention will be now described with reference to FIGS. 10A-10C. In the seventh embodiment, a cylindrical body portion  220  of the second header tank  22  is integrally formed by punching or drawing, using a metal material such as an aluminum alloy. Similarly, a cylindrical body portion  310  of the receiving unit  31  is integrally formed by the punching or the drawing, using a metal material such as an aluminum alloy. While the cylindrical body portion  310  of the receiving unit  31  is integrally formed by the punching or the drawing, the gas bypass passage  43  is formed in the cylindrical body portion  310  at the same time. 
     Specifically, a protrusion portion  311  protruding to an outside of the receiving unit  31  is formed at a side of the second header tank  22  (i.e., at a side of the connection plate  40 ) in the cylindrical body portion  310  of the receiving unit  31 , to extend in the up-down direction. A circular hole extending in the up-down direction is opened in the protrusion portion  311  to form the gas bypass passage  43 . 
     While the cylindrical body portion  310  is formed, both the upper and lower ends of the gas bypass passage  43  are opened to outside. Therefore, the openings of both the upper and lower ends of the gas bypass passage  43  are closed by using a suitable closing manner such as a sealing of a brazing material. Further, a communication hole (not shown) is opened in the cylindrical body portion  310 , so that a top portion of the gas bypass passage  43  communicates with the inner side of the receiving unit  31 , at a position around a top end within the receiving unit  31 . 
     The second communication hole  33 , through which liquid refrigerant within the receiving unit  31  flows into the lower space  22   b  of the second header tank  22 , is used as the pressure loss generation portion. Further, the opening positions of the second communication hole  33  and the gas bypass passage  43  are set so that the second communication hole  33  is directly crossed with the gas bypass passage  43 . Accordingly, the lower end portion of the gas bypass passage  43  communicates with the second communication hole  33  where the pressure loss is generated. 
     According to the seventh embodiment of the present invention, because the gas bypass passage  43  is formed at the same time while the cylindrical body portion  310  of the receiving unit  31  is integrally formed, the receiver-integrated refrigerant condenser can be manufactured in low cost. Therefore, it is unnecessary to form the gas bypass passage  43  in the connection plate  40  for temporally fixing the receiving unit  31  and the second header tank  22 . Accordingly, a dimension of the connection plate  40  in the up-down direction can be made greatly smaller as compared with a case where the gas bypass passage  41  is provided in the connection plate  40 . That is, the dimension of the connection plate  40  can be set so that the connection plate  40  contacts the receiving unit  31  and the second header tank  22  of the receiver-integrated refrigerant condenser  2 , only in the area around the first and second communication holes  33 . Thus, a clearance  44  can be formed between the receiving unit  31  and the second header tank  22  of the receiver-integrated refrigerant condenser  2 , and it can effectively restrict a heat transmission from the second header tank  22  to the receiving unit  31 . 
     In the seventh embodiment of the present invention, because the gas bypass passage  43  is provided so that gas refrigerant in the receiving unit  31  is discharged outside of the receiving unit  31 , the same effect described in the first embodiment can be obtained. 
     An eighth preferred embodiment of the present invention will be now described with reference to FIGS. 11A and 11B. In the eighth embodiment of the present invention, a throttle portion  36   a  for generating a pressure loss is formed in the filter  36 , and the outlet portion of the gas bypass pipe  34  is provided to communicate with the downstream side of the throttle portion  36   a . Specifically, a cylindrical member  312  is connected integrally into a lower inside portion of the cylindrical body portion  310  of the receiving unit  31 , and the installation pedestal  35  of the filter  36  is detachably fixed to the cylindrical member  312  by a screw member to be air-tightly attached to the cylindrical member  312  through a seal member. The filter  36  constructed by a cylindrical network member is disposed on the installation pedestal  35 , and the desiccant  37  for removing water contained in the refrigerant is disposed on the filter  36 . The desiccant  37  is constructed by a grained desiccant contained in a bag member, so that the refrigerant can pass through the desiccant  37 . 
     The filter  36  has a circular cover member  36   b  at its top end. An outer peripheral portion of the cover member  36  tightly contacts an inner peripheral surface of the cylindrical member  312 , so that an inner space of the receiving unit  31  can be partitioned into upper and lower spaces by the cover member  36   b . Further, a throttle portion  36   a  composed of a small round hole is formed in the cover member  36   b.    
     An opening area of the throttle portion  36   a  is set to be smaller than the opening area of the first and second communication holes  32 ,  33 , so that a pressure loss due to the throttle portion  36   a  is caused relative to a main flow of refrigerant shown by the arrow “b” in FIGS. 11A and 11B. The liquid refrigerant condensed in the condensation portion  23   a  flows from the upper space  22   a  of the second header tank  22  into the upper space of the receiving unit  31  upper than the cover member  36   b , through the first communication hole  32 . Thereafter, the refrigerant in the upper space of the receiving unit  31  passes through the throttle portion  36   a  and the second communication hole  33 , and flows into the lower space  22   b  of the second header tank  22 . Therefore, the pressure loss is generated in the throttle portion  36   a  relative to the main refrigerant flow shown by the arrow “b”. Accordingly, in the eighth embodiment, the opening area of the second communication hole  33  can be set to be equal to that of the first communication hole  32 . 
     On the other hand, the lower end of the gas bypass pipe  34  is fixed to the cover member  36   b  of the filter  36 , so that the outlet portion of the gas bypass pipe  34  communicates with a downstream side of the throttle portion  36 . Here, the downstream side of the throttle portion  36   a  is positioned under the cover member  36   b  inside the filter  36  composed of the cylindrical network. Thus, the outlet portion (bottom opening end) of the gas bypass pipe  34  communicates with the lower space of the cover member  36   b  after penetrating through the cover member  36   b . The inlet portion (top opening end) of the gas bypass, pipe  34  is opened in the upper space of the receiving unit  31  at a position around the top end of the receiving unit  31 . 
     According to the eighth embodiment of the present invention, the refrigerant flowing from the lower space  22   b  of the second header tank  22  into the lower space of the receiving unit  31  is throttled in the throttle portion  36   a  to generate the pressure loss. Therefore, the pressure at the downstream side of the throttle portion  36   a  is lower than the pressure in the upper space of the receiving unit  31 . That is, the pressure at the outlet portion of the gas bypass pipe  34  is lower than the pressure at the inlet portion of the gas bypass pipe  34 . Accordingly, the gas refrigerant in the upper space within the receiving unit  31  can be effectively discharged to the downstream side of the throttle portion  36   a  through the gas bypass pipe  34 . 
     According to the eighth embodiment of the present invention, the gas-refrigerant discharge unit for discharging the gas refrigerant in the upper space of the receiving unit  31  is constructed only in the receiving unit  31  by effectively using the filter  36 . Therefore, the gas-refrigerant discharge function can be readily obtained in the receiving unit  31  by only changing the structure of the receiving unit  31 , without changing the other parts in an original receiver-integrated refrigerant condenser  2 . 
     In the eighth embodiment of the present invention, the outlet portion of the gas bypass pipe  34  can be directly communicated to the throttle portion in the cover member  36   b.    
     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 first embodiment of the present invention, the receiving unit  31  is integrated with the second header tank  22  where the inlet joint  26  and the outlet joint  27  are not provided. However, the receiving unit  31  can be integrated with the first header tank  21  where the inlet joint  26  and the outlet joint  27  are provided. Further, the receiving unit  31  and any one of the first and second header tanks  21 ,  22  can be communicated through a suitable pipe member. 
     In the above-described embodiments, the present invention is applied to the receiver-integrated refrigerant condenser  2  where the core portion  23  is constructed by the condensation portion  23   a  and the super-cooling portion  23   b  which are integrated with each other. However, the present invention can be applied to a condenser where the core portion  23  is constructed only by the condensation portion  23   a , and the super-cooling portion  23   b  is formed separately from the condensation portion  23   a . In this case, the outlet joint  27  is not provided in the first header tank  21 , but is provided in the receiving unit  31 , so that the liquid refrigerant from the outlet joint flows into the super-cooling portion. Further, the present invention can be applied to a refrigerant cycle system without having the super-cooling portion  23   b.    
     In the above-described embodiments, the present invention is typically applied to the refrigerant cycle system having the receive-integrated refrigerant condenser  2 . However, the present invention can be applied to a refrigerant cycle system where the receiver is separated from the condenser. 
     Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.