Abstract:
The present invention relates to a dual air conditioner for a vehicle, which includes a rear high-temperature pipe that is connected to a rear expansion valve of a rear air conditioner and installed in such a way as to be directly branched from a dual pipe type internal heat exchanger of a front air conditioner, thereby reducing the number of required components and simplifying the manufacturing process with no need to use a connector for branching the rear high-temperature pipe from the front air conditioner, and enhancing a refrigerant movement and reducing material expenses and working process by simplifying piping work and a piping route.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a dual air conditioner for a vehicle, and more particularly, to a dual air conditioner for a vehicle, which includes a rear high-temperature pipe that is connected to a rear expansion valve of a rear air conditioner and installed in such a way as to be directly branched from expanded pipe parts of a dual pipe type internal heat exchanger of a front air conditioner. 
         [0003]    2. Background Art 
         [0004]    In general, an air conditioner for a vehicle is a car part, which is installed in a vehicle for the purpose of cooling or heating the interior of the vehicle in the summer season or the winter season or removing frost from a windshield in the rainy season or the winter season to thereby secure a driver&#39;s front and rear visual fields. Such an air conditioner typically includes a heating device and a cooling device together, so that it can heat, cool or ventilate the interior of the vehicle through the steps of selectively introducing the inside air or the outside air into the air conditioner, heating or cooling the introduced air, and blowing the heated or cooled air into the vehicle. 
         [0005]    In case of small cars having a narrow interior space, a single air conditioner that has one evaporator mounted in an engine room of the front side of the car is generally applied to the small car. However, in case of some of luxury cars or RVs (Recreational Vehicles), in order to sufficiently supply an air-conditioning environment to the rear inside room of the car, as shown in  FIG. 1 , a dual air conditioner that includes a front air conditioner  10  mounted in the engine room and having a front evaporator  14  and a rear air conditioner  20  mounted in the rear side of the car and having a rear evaporator  22  is applied to the car. 
         [0006]    The dual air conditioner including the front air conditioner  10  and the rear air conditioner  20  can simultaneously or separately operate the front evaporator  14  and the rear evaporator  22 , and the front evaporator  14  and the rear evaporator form a refrigeration cycle where refrigerant circulates through one compressor  11  and one condenser  12 . 
         [0007]      FIG. 1  is a view illustrating a state where a dual air conditioner for a vehicle according to a prior art is installed in a car,  FIG. 2  is a configurative view of the dual air conditioner for The vehicle according to the prior art, and  FIG. 3  is a perspective view showing a part where refrigerant is branched from the front air conditioner to the rear air conditioner in the dual air conditioner according to the prior art. 
         [0008]    As shown in the drawings, the front air conditioner  10  includes: a compressor  11  for sucking and compressing refrigerant; a condenser  12  for condensing refrigerant of high temperature and high pressure sent from the compressor  11 ; a front expansion valve  13  for throttling the refrigerant condensed and liquefied in the condenser  12 ; a front evaporator  14  for evaporating the liquefied refrigerant of low temperature and low pressure throttled by the front expansion valve  13  by heat-exchanging with air sent to the interior of the vehicle to thereby cool the air sent to the interior of the vehicle through the endothermic action by latent heat of vaporization of the refrigerant; and a pipe  16  for connecting the above-mentioned components with one another, so that the front air conditioner  10  can cool the front seat of the vehicle. 
         [0009]    Moreover, the front air conditioner  10  further includes a dual pipe type internal heat exchanger  15 , which has a dual pipe structure that is formed at a section of a front low-temperature pipe  16   a  for connecting the front evaporator  14  and the compressor  11  with each other and front high-temperature pipes  16   b  and  16   c  for connecting the condenser  12  and the front expansion valve  13  with each other, so as to heat-exchange refrigerants flowing in the pipes with each other. 
         [0010]    Here, the dual pipe type internal heat exchanger  15  heat-exchanges the liquid refrigerant of high-temperature and high-pressure, which is in the state before it is throttled by the front expansion valve  13 , with the refrigerant gas of low-temperature and low-pressure discharged from the front evaporator  14 , so that the refrigerant introduced into the front evaporator  14  can move smoothly, a pressure drop of the refrigerant in the front evaporator  14  can be decreased, and an overheat region (not shown) of the front evaporator  14 , which has a relatively higher temperature, can be reduced because the dual pipe type internal heat exchanger  15  is set to completely evaporate the refrigerant in order to prevent liquid refrigerant from being introduced into the compressor. 
         [0011]    Accordingly, the front air conditioner can stabilize the flow of refrigerant inside cooling tubes of the front evaporator  14  because specific volume of the refrigerant introduced into the front evaporator  14  is reduced and the pressure drop of the refrigerant in the front evaporator  14  is also reduced, and reduce the overheat region of the front evaporator  14 , which may cause a degradation of cooling performance of the air conditioner due to the relatively higher temperature since the refrigerant introduced into the compressor  11  may be overheated after being discharged from the front evaporator  14 , whereby the cooling efficiency of the air conditioner can be improved greatly. Finally, the dual air conditioner can promote efficiencies of the compressor  11 , the condenser  12 , and the front evaporator  14  to thereby cause high efficiency and miniaturization of the air conditioner. 
         [0012]    Moreover, the rear air conditioner  20  includes: a rear high-temperature pipe  23  for branching refrigerant flowing from the condenser  12  of the front air conditioner  10  toward the front expansion valve  13  to and a rear expansion valve  21  for throttling the branched refrigerant; and a rear evaporator  22  for evaporating refrigerant introduced from the rear expansion valve  21  and joining the refrigerant with refrigerant flowing from the front evaporator  14  to the compressor  11 , and cools the rear seat of the vehicle. 
         [0013]    As described above, the front air conditioner  10  having the front expansion valve  13  and the front evaporator  14  and the rear air conditioner  20  having the rear expansion valve and the rear evaporator  22  forms a refrigeration cycle commonly using one compressor  11  and one condenser  12 . 
         [0014]    Hereinafter, a refrigerant circulation process of the dual air conditioner will be described. 
         [0015]    First, when a cooling switch (not shown) is turned on, the compressor  11  is driven by a driving force of an engine to suck and compress refrigerant of low-temperature and low-pressure and to send refrigerant gas of high-temperature and high-pressure to the condenser  12 , and then, the condenser  12  heat-exchanges the refrigerant gas with the outside air and condenses the refrigerant gas into a liquid of high-temperature and high-pressure. Next, the liquid refrigerant of high-temperature and high-pressure sent from the condenser  12  passes through an outer pipe  15   b  of the dual pipe type internal heat exchanger  15 . 
         [0016]    Continuously, some of the refrigerant passing through the outer pipe  15   b  of the dual pipe type internal heat exchanger  15  is introduced and expanded into the front expansion valve  13  through the front high-temperature pipe  16   c,  and is introduced into the front evaporator  14 , and then, is evaporated by heat-exchange with air blown to the front seat of the interior of the vehicle. The remainder of the refrigerant is introduced and expanded into the rear expansion valve  21  through the rear high-temperature pipe  23  branched from the front high-temperature pipe  16   c,  and is introduced into the rear evaporator  22 , and then, is evaporated by heat-exchange with air blown to the rear seat of the interior of the vehicle. 
         [0017]    Through the above process, the front seat and the rear seat inside the vehicle are cooled. That is, the air blown by a blower (not shown) is cooled by latent heat of the refrigerant circulating in the evaporators  14  and  22  while passing through the evaporators  14  and  22 , and then, is discharged to the interior of the vehicle in a cooled state. 
         [0018]    Next, the refrigerant gas of low-temperature and low-pressure evaporated and discharged from the front evaporator  14  and the refrigerant gas of low-temperature and low-pressure evaporated and discharged from the rear evaporator  22  are joined together, and then, passes through the inner pipe  15   a  of the dual pipe type internal heat exchanger  15 . 
         [0019]    In this instance, the refrigerant gas of low-temperature and low-pressure passing through the inner pipe  15   a  of the dual pipe type internal heat exchanger  15  heat-exchanges with liquid refrigerant of high-temperature and high-pressure passing through the outer pipe  15   b  of the dual pipe type internal heat exchanger  15 , and then, is sucked into the compressor  11  and recirculated in the above refrigeration cycle. 
         [0020]    Moreover, as shown in  FIGS. 2 and 3 , the rear air conditioner  20  branches the refrigerant circulating in the front air conditioner  10  and circulates the refrigerant to the rear expansion valve  21  and the rear evaporator  22 . That is, because the rear high-temperature pipe  23  is branched from the front high-temperature pipe  16   c,  which connects the outer pipe  15   b  of the dual pipe type internal heat exchanger  15  and the front expansion valve  13  with each other, the refrigerant can be circulated to the rear expansion valve  21  and the rear evaporator  22 . 
         [0021]    In this instance, in order to connect the front high-temperature pipe  16   c  and the rear high-temperature pipe  23  with each other, as shown in  FIGS. 4 and 5 , a connector  30  is used, and the connector  30  is manufactured by the following process. 
         [0022]      FIG. 4  illustrates a state where the front high-temperature pipe  16   c  is divided and the divide front high-temperature pipes  16   c  are welded to both ends of the connector  30 , and the rear high-temperature pipe  23  is welded to the connector  30  in a perpendicular direction. 
         [0023]      FIG. 5  illustrates a state where the front high-temperature pipe  16  perforates the connector  30  and the rear high-temperature pipe  23  is welded to the connector  30  in the perpendicular direction. In this instance, the front high-temperature pipe  16   c,  which perforates the connector  30 , has a hole. 
         [0024]    However, the dual air conditioner for the vehicle according to the prior art has a problem in that the number of components and the number of manufacturing processes are increased because the rear high-temperature pipe  23  is connected to the front high-temperature pipe  16   c  via the connector  30  in order to branch the refrigerant, which circulates inside the front air conditioner  10 , and circulate the branched refrigerant to the rear air conditioner  20 . 
         [0025]    Furthermore, in the case that a distance between the dual pipe type internal heat exchanger  15  and the front expansion valve  13  is short, piping work and piping route of the front high-temperature pipe  16   c  and the rear high-temperature pipe  23  become complicated, and hence, a flow of the refrigerant is instable. 
         [0026]    Additionally, because the rear high-temperature pipe  23  is branched from the connector  30  in the perpendicular direction, the flow of the refrigerant is instable. 
       SUMMARY OF THE INVENTION 
       [0027]    Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior arts, and it is an object of the present invention to provide a dual air conditioner for a vehicle, which includes a rear high-temperature pipe that is connected to a rear expansion valve of a rear air conditioner and installed in such a way as to be directly branched from a dual pipe type internal heat exchanger of a front air conditioner, thereby reducing the number of required components and simplifying the manufacturing process with no need to use a connector for branching the rear high-temperature pipe from the front air conditioner, and enhancing a refrigerant movement and reducing material expenses and working process by simplifying piping work and a piping route. 
         [0028]    To accomplish the above object, according to the present invention, there is provided a dual air conditioner for a vehicle comprising: a front air conditioner including compressor for sucking and compressing refrigerant; a condenser for condensing refrigerant compressed in the compressor, a front expansion valve for throttling the refrigerant condensed in the condenser, a front evaporator for evaporating the refrigerant introduced from the front expansion valve, and a dual pipe type internal heat exchanger having a dual pipe structure formed at a section of a front low-temperature pipe for connecting the front evaporator and the compressor with each other and front high-temperature pipes for connecting the condenser and the front expansion valve with each other, the dual pipe type internal heat exchanger heat-exchanging the refrigerants that flow in the pipes with each other, the front air conditioner cooling the front seat side of the vehicle; and a rear air conditioner including a rear high-temperature pipe for branching refrigerant flowing from the condenser toward the front expansion valve and a rear expansion valve for throttling the branched refrigerant, and a rear evaporator for evaporating refrigerant introduced from the rear expansion valve and joining the refrigerant with refrigerant flowing from the front evaporator to the compressor, the rear high-temperature pipe being connected to a side of the dual pipe type internal heat exchanger in such a way as to be directly branched from the internal heat exchanger and being connected with the rear expansion valve, the rear air conditioner cooling the rear seat side of the vehicle. 
         [0029]    According to the present invention, the dual air conditioner for the vehicle, which includes a rear high-temperature pipe that is connected to a rear expansion valve of a rear air conditioner and installed in such a way as to be directly branched from a dual pipe type internal heat exchanger of a front air conditioner, does not require the connector branching the rear high-temperature pipe from the front air conditioner, can reduce the number of required components and simplify the manufacturing process, and allow simple piping work regardless with a distance between the dual pipe type internal heat exchanger and the front expansion valve. 
         [0030]    Moreover, the dual air conditioner according to the present, invention can enhance a refrigerant movement and reduce material expenses and working process by simplifying the piping route of the rear high-temperature pipe. 
         [0031]    Furthermore, the dual air conditioner according to the present invention can minimize a pressure loss of the refrigerant and provide a smooth flow of the refrigerant when the refrigerant passing through the outer pipe is distributed to the rear high-temperature pipe because the rear high-temperature pipe is directly branched from the expanded pipe part of the outer pipe of the dual pipe type internal heat exchanger. 
         [0032]    Additionally, the dual air conditioner according to the present invention can allow a smooth flow of the refrigerant to the pipe of high-temperature and high-pressure because the pipe is mounted to the expanded pipe part, which has a diameter larger than the dual pipe type internal heat exchanger and is less hindered in fluid movement by the inner pipe. 
         [0033]    In addition, the dual air conditioner according to the present invention can easily control, a flow rate of the refrigerant distributed to the pipes by controlling inclination angles and diameters of the front high-temperature pipe and the rear high-temperature pipe, which are respectively connected to the expanded pipe part of the outer pipe in a circumferential direction or in a longitudinal direction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]    The above and other objects, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments of the invention in conjunction with the accompanying drawings, in which: 
           [0035]      FIG. 1  is a view illustrating a state where a dual air conditioner for a vehicle according to a prior art is installed in a car; 
           [0036]      FIG. 2  is a configurative view of the dual air conditioner for the vehicle according to the prior art; 
           [0037]      FIG. 3  is a perspective view showing a part where refrigerant is branched from a front air conditioner to a rear air conditioner in the dual air conditioner according to the prior art; 
           [0038]      FIGS. 4 and 5  are perspective view illustrating a state where a front high-temperature pipe and a rear high-temperature pipe are joined by a connector in the dual air conditioner according to the prior art; 
           [0039]      FIG. 6  is a configurative view of a dual air conditioner for a vehicle according to the present invention; 
           [0040]      FIG. 7  is a perspective view showing a part where refrigerant is branched from a front air conditioner to a rear air conditioner in the dual air conditioner according to preferred embodiment of the present invention; 
           [0041]      FIG. 8  is a sectional view taken along the line of A-A of  FIG. 7 ; 
           [0042]      FIG. 9  is a sectional view illustrating a dual pipe type internal heat exchanger of  FIG. 6 ; 
           [0043]      FIG. 10  is a partially sectional view showing a flow direction of refrigerant in the dual pipe type internal heat exchanger of  FIG. 9 ; 
           [0044]      FIG. 11  is a perspective view showing a part where refrigerant is branched from the front air conditioner to the rear air conditioner in the dual air conditioner according to another preferred embodiment of the present invention; 
           [0045]      FIG. 12  is a sectional view illustrating a dual pipe type internal heat exchanger of  FIG. 11 ; 
           [0046]      FIG. 13  is an enlarged sectional view showing an expanded pipe part of  FIG. 12 ; and 
           [0047]      FIG. 14  is an enlarged sectional view showing the expanded pipe part of  FIG. 13  according to another preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0048]    Reference will be now made in detail to the preferred embodiment of the present invention with reference to the attached drawings. 
         [0049]    A dual air conditioner  100  for a vehicle according to the present invention includes a front air conditioner  200  mounted in an engine room of the vehicle and a rear air conditioner  300  mounted in the rear side of the vehicle and branching refrigerant circulating in the front air conditioner  200 . 
         [0050]    First, the front air conditioner  200  has a refrigeration cycle including a compressor  210 , a condenser  220 , a dual pipe type internal heat exchanger  250 , a front expansion valve  230 , and a front evaporator  240 , which are connected with one another in order via a pipe P. 
         [0051]    The compressor  210  is operated by receiving driving power from a power supply (an engine, a motor, or others) to thereby inhale and compress refrigerant of low-temperature and low-pressure in a gas phase discharged from the front evaporator  240  and discharge the refrigerant in the gas phase of high-temperature and high-pressure to the condenser  220 . 
         [0052]    The condenser  220  heat-exchanges the gas refrigerant of high-temperature and high-pressure discharged from the compressor  210  with the outside air, condenses it into a liquid phase of high-temperature and high-pressure, and then, discharges the condensed refrigerant to the front expansion valve  230 . 
         [0053]    The front expansion valve  230  rapidly expands the liquid refrigerant of high-temperature and high-pressure discharged from the condenser  220  through the throttling action in such a way that the refrigerant of high-temperature and high-pressure is turned into a saturated vapor phase of low-temperature and low-pressure, and then, sends the refrigerant to the front evaporator  240 . 
         [0054]    The front evaporator  240  heat-exchanges the liquid refrigerant of low-pressure throttled in the front expansion valve  230  with air sent to the interior of the vehicle, so that the refrigerant is evaporated, thereby cooling the air discharged to the interior of the vehicle due to the heat absorption effect by latent heat of the refrigerant. 
         [0055]    Continuously, the refrigerant gas of low-temperature and low-pressure evaporated from the front evaporator  240  is sucked into the compressor  210 , and is recirculated in the above cycle. 
         [0056]    Furthermore, in the above refrigerant circulation process, cooling of the interior of the vehicle is achieved in such a way that the air blown by a blower (not shown) of the air conditioner for the vehicle is cooled by the evaporated latent heat of the liquid refrigerant circulating in the evaporator  240  while passing through the front evaporator  240  and discharged to the interior of the vehicle in a cooled state. 
         [0057]    The dual pipe type internal heat exchanger  250  includes a dual pipe structure that is formed at a section of a front low-temperature pipe P 3  for connecting the front evaporator  240  and the compressor  210  with each other and a high-temperature pipe P 1  and a front high-temperature pipe P 2  for connecting the condenser  220  and the front expansion valve  230  with each other, so as to heat-exchange refrigerants flowing in the pipes with each other. 
         [0058]    The dual pipe type internal heat exchanger  250  includes: an inner pipe  251  disposed at the section of the front low-temperature pipe P 3  for connecting the front evaporator  240  and the compressor  210  with each other; and an outer pipe  252  joined to the outer circumferential surface of the inner pipe  251  in a dual pipe structure. 
         [0059]    In other words, as shown in  FIGS. 9 and 10 , the dual pipe type internal heat exchanger  250  includes: a spiral projection portion  251   a  and a spiral groove portion  251   b  formed on one of the inner pipe  251  and the outer pipe  252 ; a first refrigerant channel R 1  formed inside the inner pipe  251 ; and a second refrigerant channel R 2  formed between the inner pipe  251  and the outer pipe  252 . 
         [0060]    Here, the first refrigerant channel R 1  is a channel that refrigerant (of a gas phase) discharged from the front evaporator  240  and the rear evaporator  320  is joined and flows, and the second refrigerant channel R 2  is a channel that refrigerant (of a liquid phase) discharged from the condenser  220  flows. 
         [0061]    Referring to  FIGS. 9 and 10 , the spiral projection portion  251   a  and the spiral groove portion  251   b  are formed on the outer circumferential surface of the inner pipe  251 , and the outer pipe  252  that is a round pipe is joined to the inner pipe  251  in the dual pipe structure. 
         [0062]    In this instance, the spiral projection portion  251   a  of the inner pipe  251  is in close contact with the inner circumferential surface of the outer pipe  252 , such that the second refrigerant channel R 2  formed between the inner pipe  251  and the outer pipe  252  is formed in a spiral shape. 
         [0063]    Moreover, both end portions the spiral projection portion  251   a  and the spiral groove portion  251   b  formed on the outer circumferential surface of the inner pipe  251  are ended inside an expanded pipe part  253  formed at both end portions of the outer pipe  252 . 
         [0064]    In the meantime, both ends of the outer pipe  252  are sealed by being welded with the outer circumferential surface of the front low-temperature pipe P 3 . 
         [0065]    Furthermore, the outer pipe  252  has expanded pipe parts  253  formed at both end portions thereof, wherein one of the expanded pipe part  253  is welded and joined with the high-temperature pipe P 1  that is connected with the condenser  220 , and the other expanded pipe part  253  is welded and joined with the front high-temperature pipe P 2  that is connected with the front expansion valve  230 . 
         [0066]    As described above, because the outer pipe  252  has the expanded pipe parts  253  formed at both end portions thereof to enlarge the refrigerant channel (flow channel sectional area), it can minimize a pressure loss of the refrigerant when the refrigerant is introduced into the outer pipe  252  or when the refrigerant is discharged from the outer pipe  252 . 
         [0067]    Additionally, the rear air conditioner  300  includes: a rear high-temperature pipe P 4  for branching refrigerant of high-temperature and high-pressure heading forward the front expansion valve  230  and a rear expansion valve  310  for throttling the branched refrigerant; and a rear evaporator  320  for evaporating refrigerant of low-pressure and low-temperature introduced from the rear expansion valve  310  and joining the refrigerant to refrigerant flowing from the front evaporator  240  to the compressor  210  and cools the rear seat of the vehicle. 
         [0068]    In other words, the rear air conditioner  300  branches the refrigerant through the rear high-temperature pipe P 4  before the refrigerant is introduced into the front expansion valve  230  of the front air conditioner  200 , and then, circulates the branched refrigerant to the rear expansion valve  310  and the rear evaporator  320 . 
         [0069]    Moreover, the rear low-temperature pipe P 5  connected to an outlet of the rear evaporator  320  is connected with the front low-temperature pipe P 3  before it passes the dual pipe type internal heat exchanger  250  from the front evaporator  240 , so that the refrigerant, which is evaporated in the rear evaporator  320 , is evaporated in the front evaporator  240 , and then, joined with the refrigerant flowing in the front low-temperature pipe P 3 . 
         [0070]    Furthermore, the rear high-temperature pipe P 4  is connected to a side of the dual pipe type internal heat exchanger  250  in such a way as to be directly branched, and then, is connected with the rear expansion valve  310 . 
         [0071]    Accordingly, while the refrigerant discharged from the condenser  220  of the front air conditioner  200  flows to the front expansion valve  230  through the outer pipe  252  of the dual pipe type internal heat exchanger  250 , some of the refrigerant flowing in the outer pipe  252  is directly branched to the rear high-temperature pipe P 4 , and hence, flows to the rear expansion valve  310 . 
         [0072]    Additionally, the rear high-temperature pipe P 4  is welded and connected to the expanded pipe part  253  of the outer pipe  252  connected with the front high-temperature pipe P 2 , which is connected with the front expansion valve  230 . That is, because the rear high-temperature pipe P 4  is connected to the expanded pipe part  253  of the outer pipe  252 , it can minimize a pressure loss of the refrigerant and provide a smooth flow of the refrigerant when the refrigerant passing through the second refrigerant channel R 2  of the outer pipe  252  is distributed to the rear high-temperature pipe P 4 . 
         [0073]    In addition, a flow rate of the refrigerant distributed through the front high-temperature pipe P 2  and the rear high-temperature pipe P 4 , which are respectively connected to the expanded pipe part  253  of the outer pipe  252 , can be controlled in various ways through the following embodiments. 
         [0074]    In a first preferred embodiment, as shown in  FIG. 8 , the front high-temperature pipe P 2  and the rear high-temperature pipe P 4 , which are respectively connected to the expanded pipe part  253  of the outer pipe  252 , are connected in a circumferential direction of the expanded pipe part  253  in a state where they are spaced apart from each other at a predetermined interval. 
         [0075]    In this instance, the front high-temperature pipe P 2  is connected to one side (left side) relative to a vertical centerline C of the expanded pipe part  253  in such a way as to be inclined at a predetermined angle (θ 1 ) in a downward direction (gravitational direction) and the rear high-temperature pipe P 4  is connected to the other side (right side) relative to the vertical centerline C in such a way as to be inclined at a predetermined angle (θ 2 ) in the downward direction (gravitational direction). 
         [0076]    Here, it is preferable that the inclination angle (θ 1 ) of the front high-temperature pipe P 2  relative to the vertical centerline C of the expanded pipe part  253  is smaller than the inclination angle (θ 2 ) of the rear high-temperature pipe P 4 . 
         [0077]    That is, because the front high-temperature pipe P 2  connected to the expanded pipe part  253  is inclined at the angle, which is closer to verticality than the rear high-temperature pipe P 4 , it is more affected by the gravity force, and hence, relatively snore refrigerant introduced into the expanded pipe part  253  after passing through the second refrigerant channel P 2  of the outer pipe  252  is distributed to the front high-temperature pipe P 2  by the gravity force. 
         [0078]    As described above, the inclination angles of the front high-temperature pipe P 2  and the rear high-temperature pipe P 4 , which are respectively connected to the expanded pipe part  253  of the outer pipe  252 , are controlled so that the flow rate of the refrigerant distributed to the pipes P 2  and P 4  can be controlled. 
         [0079]    In a second preferred embodiment of the present invention, as shown in  FIGS. 11 to 13 , the front high-temperature pipe P 2  and the rear high-temperature pipe P 4 , which are respectively connected to the expanded pipe part  253  of the outer pipe  252 , are spaced apart from each other at a predetermined interval in a longitudinal direction of the expanded pipe part  253 . 
         [0080]    In this instance, the front high-temperature pipe P 2  and the rear high-temperature pipe P 4  are connected at right angles to the downward direction (gravitational direction) of the expanded pipe part  253 . 
         [0081]    Moreover, in the second embodiment illustrated in  FIGS. 11 to 13 , because the front high-temperature pipe P 2  and the rear high-temperature pipe P 4  are all connected at right angles to the downward direction of the expanded pipe part  253 , diameters D 1  and D 2  of the front high-temperature pipe P 2  and the rear high-temperature pipe P 4  are controlled so that the flow rate of the refrigerant distributed to the pipes P 2  and P 4  can be controlled. 
         [0082]    Here, it is preferable that the diameter D 1  of the front high-temperature pipe P 2  is larger than the diameter D 2  of the rear high-temperature pipe P 4  so that more refrigerant can be supplied to the front evaporator  240 , which is relatively larger than the rear evaporator. 
         [0083]    Furthermore, because the front high-temperature pipe P 2  and the rear high-temperature pipe P 4  are spaced apart from each other at a predetermined interval in the longitudinal direction of the expanded pipe part  253 , it is preferable that a length L 2  of the expanded pipe part  253 , to which the front high-temperature pipe P 2  and the rear high-temperature pipe P 4  are connected, is greater than a length L 1  of the expanded pipe part  253 , to which the high-temperature pipe P 1  is connected. 
         [0084]    In a third preferred embodiment of the present invention, as shown in  FIG. 14 , the front high-temperature pipe P 2  and the rear high-temperature pipe P 4 , which are respectively connected to the expanded pipe part  253  of the outer pipe  252 , are connected in a refrigerant flow direction of the expanded pipe part  253  in such a way as to be spaced apart from each other at a predetermined interval. 
         [0085]    In this instance, the front high-temperature pipe P 2  and the rear high-temperature pipe P 4  are respectively connected at right angles to the downward direction (gravitational direction) of the expanded pipe part  253  and have the same diameter. 
         [0086]    Additionally, in the third preferred embodiment illustrated in  FIG. 14 , because the front high-temperature pipe P 2  and the rear high-temperature pipe P 4  are all connected at right angles to the expanded pipe part  253  and have the same diameter, an arrangement order of the front high-temperature pipe P 2  and the rear high-temperature pipe P 4 , which are respectively connected in the refrigerant flow direction of the expanded pipe part  253 , is changed so that the flow rate of the refrigerant distributed to the pipes P 2  and P 4  can be controlled. 
         [0087]    Here, it is preferable that the front high-temperature pipe P 2  is connected closer to the upstream side of the refrigerant flow direction of the expanded pipe part  253  than the rear high-temperature pipe P 4  so that more refrigerant can be supplied to the front evaporator  240 , which is relatively larger than the rear evaporator. 
         [0088]    That is, relatively more the refrigerant introduced into the expanded pipe part  253  after passing through the second refrigerant channel R 2  of the outer pipe  252  is distributed to the front high-temperature pipe P 2 , which is arranged to the upstream side of the refrigerant flow direction. 
         [0089]    As described above, even though the diameters of the front high-temperature pipe P 2  and the rear high-temperature pipe  24 , which are respectively connected to the expanded pipe part  253  of the outer pipe  252  at right angles, are the same, the flow rate of the refrigerant distributed to the pipes P 2  and P 4  can be controlled according to the arrangement order of the pipes P 2  and P 4 . 
         [0090]    In the meantime, because the front high-temperature pipe P 2  and the rear high-temperature pipe P 4  are connected in the refrigerant flow direction of the expanded pipe part  253  in such a way as to be spaced apart from each other at the predetermined interval, it is preferable that the length L 2  of the expanded pipe part  253 , to which the front high-temperature pipe P 2  and the rear high-temperature pipe P 4  are connected, is greater than the length L 1  of the expanded pipe part  253 , to which the high-temperature pipe P 1  is connected. 
         [0091]    As described above, because the rear high-temperature pipe P 4  is directed connected to the expanded pipe part  253  of the outer pipe  252  of the dual pipe type internal heat exchanger  250 , the present invention does not need the connector  30 , which is required for branching the rear high-temperature pipe, and it causes reduction of the number of required components and simplification in the manufacturing process, and allow an easy and simple piping work regardless with a distance between the dual pipe type internal heat exchanger and the front expansion valve  230 . 
         [0092]    Moreover, a route of the rear high-temperature pipe P 4  is simplified, so that it can provide a smooth flow of refrigerant and cause reduction of manufacturing costs and working process. 
         [0093]    Hereinafter, actions of the dual air conditioner  100  for the vehicle according to the present invention will be described. 
         [0094]    First, the refrigerant gas of high-temperature and high-pressure, which is compressed in the compressor  210 , is introduced into the condenser  220 . The refrigerant gas introduced into the condenser  220  is condensed through heat-exchange with the outside air and phase-changed into liquid refrigerant of high-temperature and high-pressure, and then, introduced into one of the expanded pipe parts  253  of the outer pipe  252  of the dual pipe type internal heat exchanger  250 . 
         [0095]    The refrigerant of high-temperature and high-pressure introduced into the expanded pipe part  253  of the outer pipe  252  is discharged from the front evaporator  240  and the rear evaporator  320  while flowing in the second refrigerant channel R 2  of the outer pipe  252 , performs heat-exchange with the refrigerant of low-temperature and low-pressure flowing in the first refrigerant channel R 1  of the inner pipe  251 , and then, is distributed to the front high-temperature pipe P 2  and the rear high-temperature pipe P 4 , which are respectively connected to the other expanded pipe part  253 . 
         [0096]    Here, after the refrigerant distributed to the front high-temperature pipe P 2  is introduced into the front expansion valve  230 , the refrigerant becomes in an atomized state of low-temperature and low-pressure through decompression expansion, and then, is introduced into the front evaporator  240 . The refrigerant introduced into the front evaporator  240  is evaporated by heat-exchange with the air blown to the front seat of the vehicle, and at the same time, cools the air blown to the front seat of the vehicle due to the heat absorption effect by latent heat of the refrigerant. 
         [0097]    Moreover, after the refrigerant distributed to the rear high-temperature pipe P 4  is introduced into the rear expansion valve  310 , the refrigerant, becomes in an atomized state of low-temperature and low-pressure through decompression expansion, and then, is introduced into the rear evaporator  320 . The refrigerant introduced into the rear evaporator  320  is evaporated by heat-exchange with the air blown to the rear seat of the vehicle, and at the same time, cools the air blown to the rear seat of the vehicle due to the heat absorption effect by latent heat of the refrigerant. 
         [0098]    Continuously, the refrigerant gas of low-temperature and low-pressure discharged from the front evaporator  240  after evaporation and the refrigerant gas of low-temperature and low-pressure discharged from the rear evaporator  320  after evaporation are joined together through the front low-temperature pipe P 3  and the rear low-temperature pipe P 5 , and then, passes the first refrigerant channel R 1  of the inner pipe  251  of the dual pipe type internal heat exchanger  250 . 
         [0099]    In this instance, the refrigerant gas or low-temperature and low-pressure passing through the first refrigerant channel R 1  of the inner pipe  251  of the dual pipe type internal heat exchanger  250  heat-exchanges with the refrigerant gas of high-temperature and high-pressure passing through the second refrigerant channel R 2  of the outer pipe  252 , and then, is recirculated in the above-mentioned refrigeration cycle. 
         [0100]    While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.