Patent Publication Number: US-11376924-B2

Title: Vehicle air conditioning apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a vehicle air conditioning apparatus. 
     BACKGROUND ART 
     Conventionally, as an on-vehicle air conditioning apparatus is provided a system in which cooled or heated air-conditioned air is supplied to the surrounding of a seated occupant (see, for instance, JP2006-35952A and JP2016-145015A). Such a vehicle air conditioning apparatus can cool or heat the surrounding of an occupant in a locally concentrated manner. This makes it possible to provide a comfortable space to the occupant even immediately after initiation of cooling or heating operation, etc. 
     SUMMARY OF INVENTION 
     Technical Problem 
     An in-seat heat exchanger of the vehicle air conditioning apparatus described in JP2006-35952A has a simple structure such that heat is exhausted outside a vehicle while a heat source/cold source, which is assumed to be a Peltier element, is switched. This vehicle air conditioning apparatus described in JP2006-35952A has problems of poor efficiency and easy-to-occur performance/power deficiency when the Peltier element is used for cooling and/or heating treatment of air supplied. 
     Meanwhile, the seat air conditioning unit described in JP2016-145015A has a vapor compression heat exchanger installed in a seat. The problem of this seat air conditioning unit described in JP2016-145015A is that heated air during cooling and cooled air during heating cannot be exhausted outside a vehicle. In addition, the seat air conditioning unit described in JP2016-145015A needs a blower fan per exchanger. Unfortunately, this causes the size of the air conditioning unit to be enlarged, which is likely to make the structure complex and increase cost. 
     The present invention provides a solution to the above problems. The main purpose of the present invention is to provide a highly efficient vehicle air conditioning apparatus such that the internal structure of seat is simplified and heat from a vapor compression heat exchanger can be exhausted outside a vehicle. 
     Solution to Problem 
     An aspect of the present invention provides a vehicle air conditioning apparatus includes: a plurality of seat air conditioning units configured to selectively perform cooling or heating for corresponding seats installed in a cabin, respectively; and a plurality of exhaust ducts for discharging, outside the cabin, part of air used in the plurality of seat air conditioning units. At least part of the plurality of exhaust ducts is merged. 
     The vehicle air conditioning apparatus according to the present invention can reduce the number of blowing fans and thus simplify an air conditioning apparatus. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a schematic diagram of the structure of a vehicle air conditioning apparatus according to an embodiment when viewed from a lateral side. 
         FIG. 1B  is a schematic diagram of the structure of a seat air conditioning unit of the vehicle air conditioning apparatus according to the embodiment when viewed from a lateral side. 
         FIG. 2  is a schematic diagram of the structure of the vehicle air conditioning apparatus according to the embodiment when viewed from the above. 
         FIG. 3  is a diagram illustrating how the vehicle air conditioning apparatus works during cooling operation. 
         FIG. 4  is a diagram illustrating how the vehicle air conditioning apparatus works during heating operation. 
         FIG. 5A  is a schematic diagram of the structure of a front air conditioning unit when viewed from the above. 
         FIG. 5B  is a schematic diagram of the structure of the seat air conditioning unit when viewed from the above. 
         FIG. 5C  is a schematic diagram of the structure of a rear blowing unit when viewed from the above. 
         FIG. 6  is a diagram illustrating how the front air conditioning unit works during cooling operation. 
         FIG. 7A  is a diagram illustrating how the front air conditioning unit works when the temperature of a cabin front section is raised during heating operation. 
         FIG. 7B  is a diagram illustrating how the front air conditioning unit works when the outside air temperature is high (at about 0° C.) during heating operation. 
         FIG. 7C  is a diagram illustrating how the front air conditioning unit works when the outside air temperature is low during heating operation (when each seat air conditioning unit is deficient in performance). 
         FIG. 8  is a diagram illustrating how the seat air conditioning unit works during cooling operation. 
         FIG. 9  is a diagram illustrating how the seat air conditioning unit works during heating operation. 
         FIG. 10  is a schematic diagram of the structure of a seat air conditioning unit of an air conditioning apparatus according to a comparative embodiment when viewed from a lateral side. 
         FIG. 11  is a diagram illustrating how the seat air conditioning unit according to the comparative embodiment works during cooling operation. 
         FIG. 12  is a diagram illustrating how the seat air conditioning unit according to the comparative embodiment works during heating operation. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the present invention (hereinafter, referred to as the present embodiment) is described in detail with reference to the Drawings. Note that each figure just schematically depicts the present invention in a sufficiently understandable manner. Thus, the present invention is not limited to each embodiment depicted. Also, in each figure, the same elements or similar elements have the same reference numerals so as to avoid redundancy. 
     Embodiment 
     This embodiment provides an air conditioning apparatus  10  in which the number of blowing fans is reduced. In addition, this embodiment provides the air conditioning apparatus  10  so as to provide a solution to the problems of a seat air conditioning unit (see  FIGS. 10 to 12 ) of an air conditioning apparatus according to the below-described comparative embodiment. 
     &lt;Structure of Whole Air Conditioning System&gt; 
     With reference to  FIGS. 1A to 4 , the following describes the structure of the whole air conditioning apparatus  10  according to this embodiment. The air conditioning apparatus  10  is an on-vehicle air conditioning apparatus.  FIG. 1A  is a schematic diagram of the structure of the air conditioning apparatus  10  when viewed from a lateral side.  FIG. 1B  is a schematic diagram of the structure of a seat air conditioning unit  30  of the air conditioning apparatus  10  when viewed from a lateral side.  FIG. 2  is a schematic diagram of the structure of the air conditioning apparatus  10  when viewed from the above.  FIG. 3  is a diagram illustrating how the air conditioning apparatus  10  works during cooling operation.  FIG. 4  is a diagram illustrating how the air conditioning apparatus  10  works during heating operation. 
     As shown in  FIG. 1A , the air conditioning apparatus  10  includes one or more front air conditioning units  20 , a plurality of seat air conditioning units  30 , and one or more rear blowing units  40 . Here, assumed and described is a case where the number of the front air conditioning units  20  is 1, the number of the seat air conditioning units  30  is 4, and the number of the rear blowing units  40  is 2 (see  FIG. 2 ). 
     The front air conditioning unit  20  is a unit for supplying outside air (air outside a cabin) to each seat air conditioning unit  30 . The front air conditioning unit  20  is installed at a front section  102  of a vehicle  100 . In this embodiment, the front air conditioning unit  20  functions to heat outside air (air outside a cabin) and inside air (air inside the cabin). Note that the front air conditioning unit  20  may be configured to have a function of cooling outside air and inside air. 
     Each seat air conditioning unit  30  is a unit for selectively performing cooling or heating per corresponding seat  104 . Each seat air conditioning unit  30  is installed at each seat  104  arranged in a cabin  103  (see  FIG. 2 ). The inside of each seat air conditioning unit  30  contains a refrigerant for exchanging heat with the air. 
     Note that the seat air conditioning unit  30  may be a refrigerating cycle apparatus which includes a compressor, an evaporator, a condenser, and an expansion valve and through which a refrigerant circulates. In this case, during cooling operation, the evaporator generates cold air for cooling and, at the same time, the condenser generates heat. Because of this, this heat generated by the condenser is discharged, as waste heat, outside the vehicle so as to increase cooling efficiency. In addition, during heating operation, the condenser of each seat air conditioning unit  30  generates warm air for heating and, at the same time, the evaporator generates cold heat. Because of this, this cold heat generated by the evaporator is discharged, as waste heat, outside the vehicle so as to increase heating efficiency. 
     This point applies to cooling/heating operation conducted, without a refrigerant, by using a Peltier element. During cooling operation, simultaneously generated heat is drained outside the vehicle; and during heating operation, simultaneously generated cold heat is drained outside the vehicle. 
     Each rear blowing unit  40  is a unit for discharging, to the outside through a vent hole  50   b  (see  FIG. 2 ), heat and part of air (outside air) used in the front air conditioning unit  20  and each seat air conditioning unit  30 . Each rear blowing unit  40  is installed at a rear section of the vehicle  100 . 
     As shown in  FIG. 1B , each seat air conditioning unit  30  of the air conditioning apparatus  10  is structured such that during cooling/heating operation, cooled or heated air-conditioned air, for example, is supplied to the surrounding of an occupant seated on the seat  104 . Such an air conditioning apparatus  10  can supply air-conditioned air to the surrounding of an occupant. This makes it possible to provide a comfortable space to the occupant immediately after initiation of cooling or heating operation, etc. 
     As shown in  FIG. 2 , this embodiment provides the air conditioning apparatus  10  including one front air conditioning unit  20 , four seat air conditioning units  30 , two rear blowing units  40 , and ducts  60  through which air flows between the respective units. 
       FIG. 2  illustrates an example where the vehicle  100  includes one front air conditioning unit  20  at the front section  102 . In addition, the vehicle  100  includes the total of four seats  104  on the front right side, the front left side, the rear right side, and the rear left side. Meanwhile, each seat  104  is provided with one seat air conditioning unit  30 . In addition, the vehicle  100  includes the total of two rear blowing units  40 , each on the rear right side or the rear left side. 
     The ducts  60  include: air supply ducts  61  connecting the front air conditioning unit  20  and each seat air conditioning unit  30 ; exhaust ducts  62  connecting each seat air conditioning unit  30  and a corresponding rear blowing unit  40 ; and ventilation ducts  63  connecting each rear blowing unit  40  and a corresponding vent hole  50   b.    
     Each air supply duct  61  is a duct for supplying, to a corresponding seat air conditioning unit  30 , outside air so as to drain heat. The air supply duct  61  may be arranged, for instance, below a vehicle body floor, inside a center tunnel, and/or inside a center console. 
     Each exhaust duct  62  or each ventilation duct  63  is a duct for discharging, outside the cabin (outside the cabin  103 ), part of air (outside air) used in each seat air conditioning unit  30 . The ventilation duct  63  is disposed downstream of a corresponding exhaust duct  62 . Each exhaust duct  62  and the corresponding ventilation duct  63  are used to discharge, outside the cabin, the outside air with warm heat generated by each seat air conditioning unit  30  during cooling operation or cold heat generated by each seat air conditioning unit  30  during heating operation. 
     Also, in this embodiment, each seat air conditioning unit  30  is provided with: a first route (see the arrows A 11 ) through which inside air circulates; and a second route (see the arrows A 21 , A 22 , A 23 , and A 24 ) through which outside air flows. The first route and the second route are separated to give independent structures. 
     Each seat air conditioning unit  30  is likewise structured. Hereinafter, when each seat air conditioning unit  30  is distinguished, the unit on the front right side, the front left side, the rear right side, or the rear left side is denoted by adding alphabet characters “FR”, “FL”, “RR”, or “RL”, respectively, to the end of reference numeral of each seat air conditioning unit  30 . Specifically, each unit is referred to as a “seat air conditioning unit  30 FR”, “seat air conditioning unit  30 FL”, “seat air conditioning unit  30 RR”, or “seat air conditioning unit  30 RL”. 
     In addition, when each air supply duct  61  connected to the corresponding seat air conditioning unit  30  is distinguished, the duct on the front right side, the front left side, the rear right side, or the rear left side is denoted by adding alphabet characters “FR”, “FL”, “RR”, or “RL”, respectively, to the end of reference numeral of each air supply duct  61 . Specifically, each duct is referred to as an “air supply duct  61 FR”, “air supply duct  61 FL”, “air supply duct  61 RR”, or “air supply duct  61 RL”. 
     Further, when each exhaust duct  62  connected to the corresponding seat air conditioning unit  30  is distinguished, the duct on the front right side, the front left side, the rear right side, or the rear left side is denoted by adding alphabet characters “FR”, “FL”, “RR”, or “RL”, respectively, to the end of reference numeral of each exhaust duct  62 . Specifically, each duct is referred to as an “exhaust duct  62 FR”, “exhaust duct  62 FL”, “exhaust duct  62 RR”, or “exhaust duct  62 RL”. 
     Furthermore, when the ventilation duct  63  on the right side is distinguished from the ventilation duct  63  on the left side, the ventilation duct  63  on the right side is referred to as a “ventilation duct  63 R”; and the ventilation duct  63  on the left side is referred to as an “ventilation duct  63 L”. 
     The front air conditioning unit  20  is connected via four air supply ducts  61  to four seat air conditioning units  30 . Part of the four air supply ducts  61  is merged. For instance,  FIG. 2  shows an example of a shape where the four air supply ducts  61  are connected to a linear pipe arranged at substantially the middle. In other words, the four air supply ducts  61  are shaped such that a linear pipe arranged at substantially the middle branches into four directions toward the four corresponding seat air conditioning units  30 . The air outlet side (terminal end side) of each air supply duct  61  is connected to an air inlet for incorporating outside air into each seat air conditioning unit  30 . 
     The seat air conditioning unit  30 FR on the front right side is connected via the exhaust duct  62 FR to the rear blowing unit  40 R on the right side. In addition, the seat air conditioning unit  30 RR on the rear right side is connected via the exhaust duct  62 RR to the rear blowing unit  40 R on the right side. The exhaust duct  62 FR and the exhaust duct  62 RR are merged partway into one and connected to the rear blowing unit  40 R on the right side. 
     The rear blowing unit  40 R on the right side is connected via the ventilation duct  63 R to a vent hole  50   b R. The vent hole  50   b R is open to the outside of the cabin. 
     The seat air conditioning unit  30 FL on the front left side is connected via the exhaust duct  62 FL to the rear blowing unit  40 L on the left side. In addition, the seat air conditioning unit  30 RL on the rear left side is connected via the exhaust duct  62 RL to the rear blowing unit  40 L on the left side. The exhaust duct  62 FL and the exhaust duct  62 RL are merged partway into one and connected to the rear blowing unit  40 L on the left side. 
     The rear blowing unit  40 L on the left side is connected via the ventilation duct  63 L to a vent hole  50   b L. The vent hole  50   b L is open to the outside of the cabin. 
     Outside air is taken via an introduction port  50   a  into the front air conditioning unit  20  and is supplied from the front air conditioning unit  20  via each air supply duct  61  to each seat air conditioning unit  30  (see the arrows A 21  and A 22 ). The outside air supplied to each seat air conditioning unit  30  is sent from each seat air conditioning unit  30  via each exhaust duct  62  to the corresponding rear blowing unit  40  (see the arrows A 23 ). At that time, when the operation state is during cooling operation, the outside air is heated by each seat air conditioning unit  30  (that is, waste warm heat is absorbed). By contrast, when the operation state is during heating operation, the outside air is cooled by each seat air conditioning unit  30  (that is, waste cold heat is absorbed). Then, the outside air sent to each rear blowing unit  40  is sent from the rear blowing unit  40  via the corresponding ventilation duct  63  to the corresponding vent hole  50   b  so as to be discharged from the vent hole  50   b  to the outside of the cabin. At that time, the outside air is pressurized by each rear blowing unit  40  and is then delivered to the downstream side. 
     In contrast to such outside air, inside air is incorporated from the inside of the cabin into each seat air conditioning unit  30 . After heat is exchanged, as needed, depending on the operation state, the inside air is discharged to the inside of the cabin (see the arrows A 11 ). 
     &lt;How Air Conditioning System Works During Cooling Operation&gt; 
     With reference to  FIG. 3 , the following illustrates how the air conditioning apparatus  10  works during cooling operation.  FIG. 3  is a diagram illustrating how the air conditioning apparatus  10  works during cooling operation. Note that, the front air conditioning unit  20  has a built-in heater  27  configured to selectively heat inside air or outside air. In addition, each seat air conditioning unit  30  has a heat exchanger  37  including a condenser  37   a  and an evaporator  37   b.    
     As shown in  FIG. 3 , during cooling operation, the heater  27  of the front air conditioning unit  20  is in an OFF state. In addition, the front air conditioning unit  20  is in a state in which inside air circulation is stopped (that is, in a state in which incorporation of inside air from the cabin and discharge of the inside air into the cabin are stopped). Also, in the heat exchanger  37  of each seat air conditioning unit  30 , the condenser  37   a  and the evaporator  37   b  are in an ON state. 
     The front air conditioning unit  20  incorporates outside air from the introduction port  50   a  thereinto and supplies the outside air via each air supply duct  61  to each seat air conditioning unit  30 . Each seat air conditioning unit  30  takes in inside air from the cabin (see the arrows A 11 ) and heat is then exchanged by the heat exchanger  37  between a refrigerant and the inside air and between a refrigerant and the outside air. At that time, in each seat air conditioning unit  30 , the outside air is heated by the condenser  37   a  (that is, waste warm heat is given to the outside air) and the inside air is cooled by the evaporator  37   b.    
     Each seat air conditioning unit  30  sends the outside air heated by the condenser  37   a , via each exhaust duct  62 , to the corresponding rear blowing unit  40 . The rear blowing unit  40  sends the outside air via the corresponding ventilation duct  63  to the corresponding vent hole  50   b  and the outside air is then discharged from the vent hole  50   b  to the outside of the cabin. In this way, the air conditioning apparatus  10  can discharge the outside air with heat to the outside of the cabin. That is, the air conditioning apparatus  10  discards, as waste heat, warm heat generated by the condenser  37   a  of each seat air conditioning unit  30 . In addition, the air conditioning apparatus  10  can release, into the cabin, the inside air cooled by the evaporator  37   b . This enables cooling of the cabin  103  to be conducted by the air conditioning apparatus  10 . 
     &lt;How Air Conditioning System Works During Heating Operation&gt; 
     With reference to  FIG. 4 , the following illustrates how the air conditioning apparatus  10  works during heating operation.  FIG. 4  is a diagram illustrating how the air conditioning apparatus  10  works during heating operation. 
     As shown in  FIG. 4 , during heating operation, the heater  27  of the front air conditioning unit  20  is in an ON state. In addition, the front air conditioning unit  20  is in a state in which inside air circulation is implemented (that is, in a state in which incorporation of inside air from the cabin and discharge of the inside air into the cabin are implemented). Also, in the heat exchanger  37  of each seat air conditioning unit  30 , the condenser  37   a  and the evaporator  37   b  are in an ON state. Note that when each seat air conditioning unit  30  can generate adequately warm heat, the heater  27  of the front air conditioning unit  20  may be turned OFF. 
     In the front air conditioning unit  20 , inside air is taken in from the cabin, the inside air is heated by the heater  27 , and the heated inside air is then released into the cabin (see the arrow A 10 ). In addition, the front air conditioning unit  20  incorporates outside air from the introduction port  50   a  thereinto and supplies the outside air via each air supply duct  61  to each seat air conditioning unit  30 . Each seat air conditioning unit  30  takes in inside air from the cabin (see the arrows A 11 ) and heat is then exchanged by the heat exchanger  37  between a refrigerant and the inside air and between a refrigerant and the outside air. At that time, in each seat air conditioning unit  30 , the outside air is cooled by the evaporator  37   b  (that is, waste cold heat is given to the outside air) and the inside air is heated by the condenser  37   a.    
     Each seat air conditioning unit  30  sends the outside air cooled by the evaporator  37   b , via each exhaust duct  62 , to the corresponding rear blowing unit  40 . The rear blowing unit  40  sends the outside air via the corresponding ventilation duct  63  to the corresponding vent hole  50   b  and the outside air is then discharged from the vent hole  50   b  to the outside of the cabin. In this way, the air conditioning apparatus  10  can discharge the resulting outside air to the outside of the cabin. That is, the air conditioning apparatus  10  discards, as waste heat, cold heat generated by the evaporator  37   b  of each seat air conditioning unit  30 . In addition, the air conditioning apparatus  10  can release, into the cabin, the inside air heated by the condenser  37   a . This enables heating of the cabin  103  to be conducted by the air conditioning apparatus  10 . 
     &lt;Configuration of Front Air Conditioning Unit&gt; 
     With reference to  FIG. 5A , the following describes the structure of the front air conditioning unit  20 .  FIG. 5A  is a schematic diagram of the structure of the front air conditioning unit  20  when viewed from the above. 
     As shown in  FIG. 5A , the front air conditioning unit  20  includes: an inside/outside air switching damper  21  for switching an inside air flow and an outside air flow; a filter  25  for removing fine dust contained in the inside air; fans  26  for causing the inside air and/or the outside air to flow; and a heater  27  for selectively heating the inside air and/or the outside air. The inside/outside air switching damper  21  is provided with: two inside air-flowing passages (the first inside air passage  21   a   1  and the second inside air passage  21   a   2 ); and one outside air-flowing passage (outside air passage  21   b ). The front air conditioning unit  20  has two fans  26  including a fan  26   a  driven by a motor  28  for inside air and a fan  26   b  driven by a motor  28  for outside air. The heater  27  includes: a heater core  27   a  configured to heat air for air conditioning; and a heat pipe  27   b  in which a refrigerant is evaporated or condensed to transfer heat from a high-temperature part to a low-temperature part. 
     The first inside air passage  21   a   1 , the second inside air passage  21   a   2 , and the outside air passage  21   b  are arranged extending in a front-rear direction. The first inside air passage  21   a   1  and the second inside air passage  21   a   2  each have an air inlet and an air outlet installed at the cabin. In addition, the outside air passage  21   b  has an air inlet installed outside the cabin and its air outlet side is connected to each air supply duct  61 . 
     The first inside air passage  21   a   1  and the second inside air passage  21   a   2  are adjacent to each other and share a common space in their partway. The common space is provided with the filter  25 , the fan  26   a , and the heater core  27   a . The fan  26   a  is positioned downstream of the filter  25 . The heater core  27   a  is positioned downstream of the fan  26   a.    
     The second inside air passage  21   a   2  and the outside air passage  21   b  are adjacent to each other. The fan  26   b  is arranged in the inside of the outside air passage  21   b . In this embodiment, the fan  26   a  and the fan  26   b  are arranged at substantially the same vehicle-longitudinal position. In addition, the heat pipe  27   b  is arranged in the inside of the outside air passage  21   b  and the second inside air passage  21   a   2 . The heat pipe  27   b  is positioned downstream of the heater core  27   a.    
     Switching doors  24   a  and  24   b  are provided between the first inside air passage  21   a   1  and the second inside air passage  21   a   2 . The switching door  24   a  is positioned upstream of the filter  25 . In addition, the switching door  24   b  is positioned downstream of the heater core  27   a  and upstream of the heat pipe  27   b . Also, the inside of the outside air passage  21   b  has a switching door  24   c . The switching door  24   c  is positioned upstream of the fan  26   b . The switching doors  24   a ,  24   b , and  24   c  control switching in or between passages. The switching door  24   a , the first inside air passage  21   a   1 , the second inside air passage  21   a   2 , the outside air passage  21   b , and the switching door  24   c  provide a passage switching device  24 . 
     The front air conditioning unit  20  causes inside air taken in from the cabin to be pressurized by the fan  26   a  and then to flow, via either the first inside air passage  21   a   1  or the second inside air passage  21   a   2  or both, to the downstream side. At that time, the front air conditioning unit  20 , depending on the operation state, causes the inside air to be heated by the heater core  27   a  and/or uses the heat pipe  27   b  to exchange heat between the inside air and the outside air. After that, the front air conditioning unit  20  releases the inside air into the cabin. 
     In addition, the front air conditioning unit  20  causes outside air taken in from the outside to be pressurized by the fan  26   b  and then to flow, via the outside air passage  21   b , to the downstream side. At that time, the front air conditioning unit  20 , depending on the operation state, uses the heat pipe  27   b  to exchange heat between the inside air and the outside air. After that, the front air conditioning unit  20  supplies the outside air via each air supply duct  61  to each seat air conditioning unit  30 . 
     &lt;Configuration of Seat Air Conditioning Unit&gt; 
     With reference to  FIG. 5B , the following describes the structure of each seat air conditioning unit  30 .  FIG. 5B  is a schematic diagram of the structure of the seat air conditioning unit  30  when viewed from the above. 
     As shown in  FIG. 5B , each seat air conditioning unit  30  includes: an inside/outside air switching damper  31  for switching an inside air flow and an outside air flow; a fan  36  for causing the inside air to flow; and a heat exchanger  37  for exchanging heat between a refrigerant and the inside air and between a refrigerant and the outside air. The inside/outside air switching damper  31  is provided with: two inside air-flowing passages (the first inside air passage  31   a   1  and the second inside air passage  31   a   2 ); and two outside air-flowing passages (the first outside air passage  31   b   1  and the second outside air passage  31   b   2 ). In addition, the seat air conditioning unit  30  has the heat exchanger  37  including a condenser  37   a , in which a refrigerant is condensed, and an evaporator  37   b , in which a refrigerant is evaporated. Here, the condenser  37   a  and the evaporator  37   b  of the seat air conditioning unit  30 , together with a compressor (not shown) and an expansion valve (not shown), are described to constitute a refrigerating cycle apparatus through which a refrigerant circulates. 
     The first inside air passage  31   a   1 , the second inside air passage  31   a   2 , the first outside air passage  31   b   1 , and the second outside air passage  31   b   2  are arranged extending in a front-rear direction. The first inside air passage  31   a   1  and the second inside air passage  31   a   2  share an air inlet  32   a  and each has an air outlet installed at the cabin. In addition, the first outside air passage  31   b   1  and the second outside air passage  31   b   2  shares an air inlet  32   b  installed outside the cabin and their air outlet side is connected to the corresponding exhaust duct  62 . 
     The first inside air passage  31   a   1  and the second inside air passage  31   a   2  are formed such that the air inlet  32   a  branches into two passages. The first inside air passage  31   a   1  is disposed next to the right outer side of the first outside air passage  31   b   1 . The second inside air passage  31   a   2  is disposed next to the left outer side of the second outside air passage  31   b   2 . The first outside air passage  31   b   1  and the second outside air passage  31   b   2  are adjacent to each other so as to pass through, from the air inlet  32   b , substantially the vehicle widthwise center of the seat air conditioning unit  30 . 
     The first inside air passage  31   a   1  and the first outside air passage  31   b   1  share a common space, i.e., a condenser air passage  71 , in their partway. The common space is provided with the condenser  37   a . The second inside air passage  31   a   2  and the second outside air passage  31   b   2  share a common space, i.e., an evaporator air passage  72 , in their partway. The common space is provided with the evaporator  37   b . In this embodiment, the condenser  37   a  and the evaporator  37   b  are arranged at substantially the same vehicle-longitudinal position. 
     Switching doors  34   a  and  34   b  are provided between the first inside air passage  31   a   1  and the first outside air passage  31   b   1 . The switching door  34   a  is positioned upstream of the condenser  37   a  and disposed to close any one of the outside air inlet  71   a  or the inside air outlet  71   c  of the condenser air passage  71 , and open the other. In addition, the switching door  34   b  is positioned downstream of the condenser  37   a  and disposed to close any one of the inside air outlet  71   b  or the outside air outlet  71   d  of the condenser air passage  71  and open the other. 
     Switching doors  34   c  and  34   d  are provided between the second inside air passage  31   a   2  and the second outside air passage  31   b   2 . The switching door  34   c  is positioned upstream of the evaporator  37   b  and disposed to close any one of the outside air inlet  72   a  or the inside air inlet  72   c  of the evaporator air passage  72 , and open the other. In addition, the switching door  34   d  is positioned downstream of the evaporator  37   b  and disposed to close any one of the outside air outlet  72   b  or the inside air outlet  72   d  of the evaporator air passage, and open the other. The switching doors  34   a ,  34   b ,  34   c , and  34   d  are provided for switching between passages. The switching doors  34   a  and  34   c , the first inside air passage  31   a   1 , the first outside air passage  31   b   1 , the second outside air passage  31   b   2 , and the second inside air passage  31   a   2  provide a switching device  34  configured to perform switching between the passages such that during cooling operation, the outside air is guided in a direction toward the condenser  37   a  and during heating operation, the outside air is guided to a direction toward the evaporator  37   b . Accordingly, the passage switching device  34  can perform switching between the passage such that during cooling operation, the outside air is guided in a direction toward the condenser  37   a  and during heating operation, the outside air is guided to a direction toward the evaporator  37   b.    
     The seat air conditioning unit  30  causes inside air taken in from the cabin to be pressurized by the fan  36  and then to flow, via either the first inside air passage  31   a   1  or the second inside air passage  31   a   2 , to the downstream side. At that time, in the seat air conditioning unit  30 , heat is exchanged by the heat exchanger  37  between a refrigerant and the inside air and between a refrigerant and the outside air. After that, the seat air conditioning unit  30  releases the inside air into the cabin. 
     Further, the seat air conditioning unit  30  causes outside air taken in from the outside to flow, via either the first outside air passage  31   b   1  or the second outside air passage  31   b   2 , to the downstream side. At that time, in the seat air conditioning unit  30 , heat is exchanged by the heat exchanger  37  between a refrigerant and the inside air and between a refrigerant and the outside air. After that, the seat air conditioning unit  30  sends the outside air, via the corresponding exhaust duct  62 , to the corresponding rear blowing unit  40 . 
     Note that in order to circulate inside air between each seat air conditioning unit  30  and the cabin, the seat air conditioning unit  30  has the fan  36  on the inside air inlet  32   a  side. However, each seat air conditioning unit  30  is provided with no fan (blowing fan) on the outside air inlet  32   b  side. 
     This is because the air conditioning apparatus  10  has the following configuration which makes it possible to omit a fan (blowing fan) on the outside air inlet  32   b  side. 
     (a) The air conditioning apparatus  10  is structured such that outside air is pressurized by the fan  26   b  (see  FIG. 5A ) of the front air conditioning unit  20  and is then delivered from the front air conditioning unit  20  to each seat air conditioning unit  30 . 
     (b) The air conditioning apparatus  10  is structured such that a fan  46  driven by a motor  28  (see  FIG. 5C ) of each rear blowing unit  40  sucks outside air from each seat air conditioning unit  30  to the rear blowing unit  40 . 
     Such an air conditioning apparatus  10  makes it possible to reduce the number of parts by the number of fans (blowing fans) omitted on the outside air inlet  32   b  side. For instance, when the air conditioning apparatus  10  has four seat air conditioning units  30 , four outside air-use fans (blowing fans) can be omitted. In addition, in the air conditioning apparatus  10 , the size of each seat air conditioning unit  30  can be made compact. 
     &lt;Configuration of Rear Blowing Unit&gt; 
     With reference to  FIG. 5C , the following describes the structure of each rear blowing unit  40 .  FIG. 5C  is a schematic diagram of the structure of the rear blowing unit  40  when viewed from the above. 
     As shown in  FIG. 5C , each rear blowing unit  40  includes an outside air passage  41   b  through which outside air flows and the fan  46  configured to cause the outside air to flow. Of the outside air passage  41   b , the air inlet side (starting end side) is connected to the corresponding exhaust duct  62 ; and the air outlet side (terminal end side) is connected to a ventilation duct  63 . The fan  46  is arranged in the inside of the outside air passage  41   b.    
     &lt;How Front Air Conditioning Unit Works During Cooling Operation&gt; 
     With reference to  FIG. 6 , the following illustrates how the front air conditioning unit  20  works during cooling operation.  FIG. 6  is a diagram illustrating how the front air conditioning unit  20  works during cooling operation. 
     As shown in  FIG. 6 , in the front air conditioning unit  20  during cooling operation, the switching doors  24   a  and  24   b  are operated to open the first inside air passage  21   a   1  and close the second inside air passage  21   a   2 . In addition, the switching door  24   c  is in a state in which the outside air passage  21   b  is open. Further, the heater core  27   a  and the heat pipe  27   b  are turned OFF. 
     While kept under such conditions, the front air conditioning unit  20  does not actuate the fan  26   a , resulting in a state in which inside air circulation is stopped. Meanwhile, the front air conditioning unit  20  actuates the fan  26   b . Accordingly, outside air is made to flow through the outside air passage  21   b  to the downstream side and then to pass through the heat pipe  27   b . At that time, heat is not exchanged between the outside air and the inside air. 
     &lt;How Front Air Conditioning Unit Works During Heating Operation&gt; 
     With reference to  FIGS. 7A to 7C , the following illustrates how the front air conditioning unit  20  works when the temperature of a cabin front section is raised during heating operation.  FIG. 7A  is a diagram illustrating how the front air conditioning unit  20  works when the temperature of a cabin front section is raised during heating operation.  FIG. 7B  is a diagram illustrating how the front air conditioning unit  20  works when the outside air temperature is high (at about 0° C.) during heating operation.  FIG. 7C  is a diagram illustrating how the front air conditioning unit  20  works when the outside air temperature is low during heating operation (when each seat air conditioning unit  30  is deficient in performance). 
     (How Front Air Conditioning Unit Works When Temperature of Cabin Front Section is Raised) 
     When the temperature of the cabin front section is raised, the front air conditioning unit  20  actuates the heater core  27   a  to elevate the cabin temperature around the front air conditioning unit  20 . When the temperature of the cabin front section is raised in such a manner, as shown in  FIG. 7A , the switching doors  24   a  and  24   b  in the front air conditioning unit  20  are operated to open the first inside air passage  21   a   1  and close the second inside air passage  21   a   2 . In addition, the switching door  24   c  is in a state in which the outside air passage  21   b  is open. Further, the heater core  27   a  is turned ON and the heat pipe  27   b  is turned OFF. 
     While kept under such conditions, the front air conditioning unit  20  actuates the fan  26   a  to cause inside air to flow through the first inside air passage  21   a   1  to the downstream side. At that time, fine dust is removed by the filter  25 . Further, the inside air is then made to pass through the heater core  27   a  for heating. Meanwhile, the front air conditioning unit  20  actuates the fan  26   b . Accordingly, outside air is made to flow through the outside air passage  21   b  to the downstream side and then to pass through the heat pipe  27   b . At that time, heat is not exchanged between the outside air and the inside air. After that, the front air conditioning unit  20  delivers the outside air via each air supply duct  61  to the evaporator  37   b  of each seat air conditioning unit  30 . 
     (How Front Air Conditioning Unit Works When Outside Air Temperature is High) 
     When the outside air temperature is high (at about 0° C.), the front air conditioning unit  20  only blows air to each seat air conditioning unit  30 . When the outside air temperature is this high, as shown in  FIG. 7B , the switching doors  24   a  and  24   b  in the front air conditioning unit  20  are operated to open the first inside air passage  21   a   1  and close the second inside air passage  21   a   2 . In addition, the switching door  24   c  is in a state in which the outside air passage  21   b  is open. Further, the heater core  27   a  and the heat pipe  27   b  are turned OFF. 
     While kept under such conditions, the front air conditioning unit  20  does not actuate the fan  26   a , resulting in a state in which inside air circulation is stopped. Meanwhile, the front air conditioning unit  20  actuates the fan  26   b  to cause outside air to flow through the first outside air passage  21   b  to the downstream side and to pass through the heat pipe  27   b . At that time, heat is not exchanged between the outside air and the inside air. After that, the front air conditioning unit  20  delivers the outside air via each air supply duct  61  to the evaporator  37   b  of each seat air conditioning unit  30 . 
     (How Front Air Conditioning Unit Works When Outside Air Temperature is Low) 
     When the outside air temperature is low, the front air conditioning unit  20  actuates the heater core  27   a  and the heat pipe  27   b  to elevate the cabin temperature and the blowing temperature of the inside air as well as to increase the blowing temperature of the outside air delivered to each seat air conditioning unit  30 . When the outside air temperature is this low, as shown in  FIG. 7C , the switching doors  24   a  and  24   b  in the front air conditioning unit  20  are operated to open the first inside air passage  21   a   1  and the second inside air passage  21   a   2 . In addition, the switching door  24   c  is in a state in which the outside air passage  21   b  is open. Further, the heater core  27   a  and the heat pipe  27   b  are turned ON. Note that when each seat air conditioning unit  30  can generate adequate warm heat, the heater  27  of the front air conditioning unit  20  may be turned OFF. 
     While kept under such conditions, the front air conditioning unit  20  actuates the fan  26   a  to cause inside air to flow through the first inside air passage  21   a   1  and the second inside air passage  21   a   2 . At that time, fine dust is removed by the filter  25 . Further, the inside air is then made to pass through the heater core  27   a  for heating. Meanwhile, the front air conditioning unit  20  actuates the fan  26   b  to cause outside air to flow through the first outside air passage  21   b  to the downstream side and to pass through the heat pipe  27   b . At that time, heat is exchanged between the outside air and the inside air by means of the heat pipe  27   b . After that, the front air conditioning unit  20  delivers the outside air via each air supply duct  61  to the evaporator  37   b  of each seat air conditioning unit  30 . 
     Note that the operation illustrated in  FIG. 7C  is described below. When the outside air temperature is low, the heating capacity of each seat air conditioning unit  30  is likely to be insufficient. In this case, the operation aims at making it possible for each seat air conditioning unit  30  to immediately blow warm air to an occupant. 
     Specifically, for instance, when the outside air temperature is low, namely when the heating capacity of each seat air conditioning unit  30  is likely to be insufficient, electric vehicles without any engine cannot utilize, for heating, heat generated by the engine. In addition, in view of their performance characteristics, refrigerating cycle apparatuses need more time to generate warm air than to generate cold air. Because of this, when the outside air temperature is low, the seat air conditioning unit  30  requires considerable time to generate sufficiently warm air. Thus, when the outside air temperature is low, as shown in  FIG. 7C , the heater  27  of the front air conditioning unit  20  in the air conditioning apparatus  10  is turned ON. This compensates the insufficient heating capacity of each seat air conditioning unit  30  and makes it possible for the seat air conditioning unit  30  to immediately blow warm air to an occupant. 
     &lt;How Seat Air Conditioning Unit Works During Cooling Operation&gt; 
     With reference to  FIG. 8 , the following illustrates how each seat air conditioning unit  30  works during cooling operation.  FIG. 8  is a diagram illustrating how the seat air conditioning unit  30  works during cooling operation. 
     As shown in  FIG. 8 , in each seat air conditioning unit  30  during cooling operation, the switching doors  34   a  and  34   b  are operated to close the first inside air passage  31   a   1  and open the first outside air passage  31   b   1 . In addition, the switching doors  34   c  and  34   d  are operated to close the second outside air passage  31   b   2  and open the second inside air passage  31   a   2 . Further, the condenser  37   a  and the evaporator  37   b  are turned ON. 
     While kept under such conditions, the seat air conditioning unit  30  actuates the fan  36  to cause inside air to flow through the second inside air passage  31   a   2  to the downstream side and then to pass through the evaporator  37   b . At that time, heat is exchanged between the inside air and a refrigerant flowing through the evaporator  37   b . This cools the inside air. After that, the seat air conditioning unit  30  releases the inside air into the cabin. In addition, each seat air conditioning unit  30  causes outside air delivered from the front air conditioning unit  20  to flow through the first outside air passage  31   b   1  and then to pass through the condenser  37   a . At that time, heat is exchanged between the outside air and a refrigerant flowing through the condenser  37   a . This heats the outside air. After that, the seat air conditioning unit  30  sends the outside air, via the corresponding exhaust duct  62 , to the corresponding rear blowing unit  40 . 
     &lt;How Seat Air Conditioning Unit Works During Heating Operation&gt; 
     With reference to  FIG. 9 , the following illustrates how each seat air conditioning unit  30  works during heating operation.  FIG. 9  is a diagram illustrating how the seat air conditioning unit  30  works during heating operation. 
     As shown in  FIG. 9 , in each seat air conditioning unit  30  during heating operation, the switching doors  34   a  and  34   b  are operated to open the first inside air passage  31   a   1  and close the first outside air passage  31   b   1 . In addition, the switching doors  34   c  and  34   d  are operated to open the second outside air passage  31   b   2  and close the second inside air passage  31   a   2 . Further, the condenser  37   a  and the evaporator  37   b  are turned ON. 
     While kept under such conditions, each seat air conditioning unit  30  actuates the fan  36  to cause inside air to flow through the first inside air passage  31   a   1  to the downstream side and then to pass through the condenser  37   a . At that time, heat is exchanged between the inside air and a refrigerant flowing through the condenser  37   a . This heats the inside air. After that, the seat air conditioning unit  30  releases the inside air into the cabin. In addition, each seat air conditioning unit  30  causes outside air delivered from the front air conditioning unit  20  to flow through the second outside air passage  31   b   2  and then to pass through the evaporator  37   b . At that time, heat is exchanged between the outside air and a refrigerant flowing through the evaporator  37   b . This cools the outside air. After that, the seat air conditioning unit  30  sends the outside air, via the corresponding exhaust duct  62 , to the corresponding rear blowing unit  40 . 
     &lt;How Comparative Embodiment is Configured and Works&gt; 
     Meanwhile, the idea of the air conditioning apparatus  10  according to the present embodiment can also provide a solution to the problems of an air conditioning apparatus  110  according to the following comparative embodiment. The air conditioning apparatus  110  according to the comparative embodiment is structured while ducts are considered to be simplified. With reference to  FIGS. 10 to 12 , the following describes the structure and problems of the air conditioning apparatus  110  according to the comparative embodiment.  FIG. 10  is a schematic diagram of the structure of a seat air conditioning unit  130  of the air conditioning apparatus  110  according to the comparative embodiment when viewed from a lateral side.  FIG. 11  is a diagram illustrating how the seat air conditioning unit  130  according to the comparative embodiment works during cooling operation.  FIG. 12  is a diagram illustrating how the seat air conditioning unit  130  according to the comparative embodiment works during heating operation. 
     When compared to the air conditioning apparatus  10  according to the present embodiment, the air conditioning apparatus  110  according to the comparative embodiment as shown in  FIG. 10  has the seat air conditioning unit  130  instead of the seat air conditioning unit  30  (see  FIG. 5B ). This point is a difference. 
     The seat air conditioning unit  130  according to the comparative embodiment is arranged below the seat  104 . The seat air conditioning unit  130  according to the comparative embodiment includes: two fans  136  ( 136   a ,  136   b ) for causing inside air and outside air to flow; and a heat exchanger  137  for exchanging heat between a refrigerant and the inside air and between a refrigerant and the outside air. In addition, the seat air conditioning unit  130  according to the comparative embodiment has the heat exchanger  137  including a condenser  137   a , in which a refrigerant is condensed, and an evaporator  137   b , in which a refrigerant is evaporated. 
     Also, the seat air conditioning unit  130  according to the comparative embodiment is provided with: two inside air-flowing passages (the first inside air passage  131   a   1  and the second inside air passage  131   a   2 ); and two outside air-flowing passages (the first outside air passage  131   b   1  and the second outside air passage  131   b   2 ). The first outside air passage  131   b   1  and the second outside air passage  131   b   2  are adjacent to each other in a front-rear direction. The first inside air passage  131   a   1  is disposed forwardly of and next to the first outside air passage  131   b   1 . The second inside air passage  131   a   2  is disposed rearwardly of and next to the second outside air passage  131   b   2 . 
     The first inside air passage  131   a   1  is shaped like an inverted L letter, extending from the bottom to the top, and having an upper end side protruding forwardly below the seat  104 . The first inside air passage  131   a   1  has openings at a lower end portion and a front end portion on the upper end side. The opening of the lower end portion functions as an air inlet and the opening of the front end portion on the upper end side functions as an air outlet. The first inside air passage  131   a   1  is structured such that inside air is taken in from the opening (air inlet) of the lower end portion and the inside air is discharged, to the cabin, from the opening (air outlet) of the front end portion on the upper end side. 
     The second inside air passage  131   a   2  is shaped like a crank, extending from the bottom to the top, having a partway portion curved reward, and further having an upper end side protruding forward so as to be connected to a seatback portion of the seat  104 . The second inside air passage  131   a   2  has openings at a lower end portion and a front end portion on the upper end side. The opening of the lower end portion functions as an air inlet and the opening of the front end portion on the upper end side functions as an air outlet. The second inside air passage  131   a   2  is structured such that inside air is taken in from the opening (air inlet) of the lower end portion and the inside air is discharged via the seat  104 , to the cabin, from the opening (air outlet) of the front end portion on the upper end side. 
     The first outside air passage  131   b   1  and the second outside air passage  131   b   2  are shaped like an inverted U letter, extending from the bottom to the top, having a partway portion curved reward, and having a leading end portion bent downward. The first outside air passage  131   b   1  and the second outside air passage  131   b   2  have openings at two lower end portions. The opening of the lower end portion (hereinafter, referred to as “one lower end portion”) sandwiched between the first inside air passage  131   a   1  and the second inside air passage  131   a   2  functions as an air inlet and the opening of the other lower end portion functions as an air outlet. An introduction pipe  160   a  is attached to the opening (air inlet) of the one lower end portion. In addition, a discharge pipe  160   b  is attached to the opening (air outlet) of the other lower end portion. The first outside air passage  131   b   1  and the second outside air passage  131   b   2  are structured such that outside air is introduced thereinto from the opening (air inlet) of the one lower end portion and the outside air is discharged outside the cabin from the opening (air outlet) of the other lower end portion. 
     The first inside air passage  131   a   1  and the first outside air passage  131   b   1  share a common space in their partway. The common space includes, in sequence from the bottom, the condenser  137   a  and the fan  136   a . The second inside air passage  31   a   2  and the second outside air passage  31   b   2  share a common space in their partway. The common space includes, in sequence from the bottom, the evaporator  137   b  and the fan  136   b . In the comparative embodiment, the condenser  137   a  and the evaporator  137   b  are arranged at substantially the same height position. In addition, the fan  136   a  and the fan  136   b  are arranged at substantially the same height position. 
     Switching doors  134   a  and  134   b  are provided between the first inside air passage  131   a   1  and the first outside air passage  131   b   1 . The switching door  134   a  is positioned below the condenser  137   a  and the fan  136   a . In addition, the switching door  134   b  is positioned above the condenser  137   a  and the fan  136   a.    
     Switching doors  134   c  and  134   d  are provided between the second inside air passage  131   a   2  and the second outside air passage  131   b   2 . The switching door  134   c  is positioned below the evaporator  137   b  and the fan  136   b . In addition, the switching door  134   d  is positioned above the condenser  137   a  and the fan  136   a.    
     As shown in  FIG. 11 , in the seat air conditioning unit  130  according to the comparative embodiment during cooling operation, the switching doors  134   a  and  134   b  are operated to close the first inside air passage  131   a   1  and open the first outside air passage  131   b   1 . In addition, the switching doors  134   c  and  134   d  are operated to close the second outside air passage  131   b   2  and open the second inside air passage  131   a   2 . Further, the condenser  137   a  and the evaporator  137   b  are turned ON. 
     Under such conditions, the seat air conditioning unit  130  according to the comparative embodiment actuates the fan  136   a  and the fan  136   b . By doing so, the seat air conditioning unit  130  according to the comparative embodiment causes inside air to flow through the second inside air passage  131   a   2  to the downstream side (in the upper direction of  FIG. 11 ) and then to pass through the evaporator  137   b . At that time, heat is exchanged between the inside air and a refrigerant flowing through the evaporator  137   b . This cools the inside air. After that, the seat air conditioning unit  130  according to the comparative embodiment releases the inside air into the cabin. In addition, the seat air conditioning unit  130  according to the comparative embodiment causes outside air to flow through the first outside air passage  131   b   1  to the downstream side (in the upper direction of  FIG. 11 ) and then to pass through the condenser  137   a . At that time, heat is exchanged between the outside air and a refrigerant flowing through the condenser  137   a . This heats the outside air. After that, the seat air conditioning unit  130  according to the comparative embodiment delivers the outside air to the outside of the cabin. 
     As shown in  FIG. 12 , in the seat air conditioning unit  130  according to the comparative embodiment during heating operation, the switching doors  134   a  and  134   b  are operated to open the first inside air passage  131   a   1  and close the first outside air passage  131   b   1 . In addition, the switching doors  134   c  and  134   d  are operated to open the second outside air passage  131   b   2  and close the second inside air passage  131   a   2 . Further, the condenser  137   a  and the evaporator  137   b  are turned ON. 
     Under such conditions, the seat air conditioning unit  130  according to the comparative embodiment actuates the fan  136   a  and the fan  136   b . By doing so, the seat air conditioning unit  130  according to the comparative embodiment causes inside air to flow through the first inside air passage  131   a   1  to the downstream side (in the upper direction of  FIG. 11 ) and then to pass through the condenser  137   a . At that time, heat is exchanged between the inside air and a refrigerant flowing through the condenser  137   a . This heats the inside air. After that, the seat air conditioning unit  130  according to the comparative embodiment releases the inside air into the cabin. In addition, the seat air conditioning unit  130  according to the comparative embodiment causes outside air to flow through the second outside air passage  131   b   2  to the downstream side (in the upper direction of  FIG. 11 ) and then to pass through the evaporator  137   b . At that time, heat is exchanged between the outside air and a refrigerant flowing through the evaporator  137   b . This cools the outside air. After that, the seat air conditioning unit  130  according to the comparative embodiment delivers the outside air to the outside of the cabin. 
     The air conditioning apparatus  110  according to the comparative embodiment as so structured has the following problems. 
     (1) As shown in  FIG. 10 , the air conditioning apparatus  110  according to the comparative embodiment has a low degree of design freedom because air flow in or out of the seat air conditioning unit  130  is complicated. 
     (2) As shown in  FIG. 10 , the air conditioning apparatus  110  according to the comparative embodiment is difficult to secure space for the fans  136  and the switching doors  134   a ,  134   b ,  134   c , and  134   d  because the seat air conditioning unit  130  is configured extending in a vertical direction. Such an air conditioning apparatus  110  according to the comparative embodiment has a low degree of design freedom because the height T 130  from a vehicle body floor  101   a  is a relatively large value and is required. 
     (3) As shown in  FIG. 10 , the air conditioning apparatus  110  according to the comparative embodiment needs, as the fans  136  for the heat exchanger, two fans  136   a  and  136   b  per seat air conditioning unit  130 . Such an air conditioning apparatus  110  according to the comparative embodiment needs a large number of parts, so that the size and cost of the seat air conditioning unit  130  increase. 
     (4) As shown in  FIG. 10 , the air conditioning apparatus  110  according to the comparative embodiment needs a plurality of vent holes Ho 1  and Ho 2  on the vehicle body side (e.g., the vehicle body floor  101   a ) so as to secure air passages to the heat exchanger  137 . The vent hole Ho 1  is an inlet vent hole and the vent hole Ho 2  is an outlet vent hole. The air conditioning apparatus  110  according to the comparative embodiment needs to provide two (inlet/outlet) vent holes (Ho 1 /Ho 2 ) per seat air conditioning unit  130 . Due to this, if the number of the seat air conditioning units  130  is 4, for instance, the air conditioning apparatus  110  according to the comparative embodiment needs to provide 8 vent holes (Ho 1  and Ho 2 ). Because such an air conditioning apparatus  110  according to the comparative embodiment is provided with a plurality of the vent holes Ho 1  and Ho 2  on the vehicle body side, rainwater and/or running noise may enter the cabin. 
     (5) Regarding the air conditioning apparatus  110  according to the comparative embodiment, when the outside air temperature is low, the heat exchanger  137  may not effectively function because the evaporator  137   b  of the seat air conditioning unit  130  is frosted. 
     In contrast to the air conditioning apparatus  110  according to the comparative embodiment, the air conditioning apparatus  10  according to the present embodiment has the following advantages. 
     (1) As shown in  FIG. 5B , the air conditioning apparatus  10  according to the present embodiment has an increased degree of design freedom because air flow in or out of the seat air conditioning unit  30  is simplified. 
     (2) As shown in  FIG. 5B , the air conditioning apparatus  10  according to the present embodiment is easy to secure space for the fan  36  and the switching doors  34   a ,  34   b ,  34   c , and  34   d  because the seat air conditioning unit  30  is configured extending in a front-rear direction. Such an air conditioning apparatus  10  according to the present embodiment differs from the air conditioning apparatus  110  according to the comparative embodiment. The height from the vehicle body floor  101   a  can be lowered, so that the degree of design freedom can be enhanced. 
     (3) As shown in  FIG. 5B , the air conditioning apparatus  10  according to the present embodiment is provided, per seat air conditioning unit  30 , with just one fan  36  for the inside air heat exchanger, so that a fan (blowing fan) for the outside air heat exchanger can be omitted. In such an air conditioning apparatus  10  according to the present embodiment, the number of parts can be reduced by the number of the fans (blowing fans) for the outside air heat exchanger, so that the size and cost of the seat air conditioning unit  30  can improve. 
     (4) As shown in  FIG. 5B , the air conditioning apparatus  10  according to the present embodiment differs from the air conditioning apparatus  110  according to the comparative embodiment and does not have to be provided with a plurality of vent holes on the vehicle body side (e.g., the vehicle body floor) so as to secure air passages to the heat exchanger  37 . Such an air conditioning apparatus  10  according to the present embodiment differs from the air conditioning apparatus  110  according to the comparative embodiment, such that rainwater and/or running noise can be prevented from entering the cabin. 
     (5) Regarding the air conditioning apparatus  10  according to the present embodiment, like the air conditioning apparatus  110  according to the comparative embodiment, when the outside air temperature is low, the evaporator  37   b  of each seat air conditioning unit  30  may be frosted. However, as shown in  FIG. 7C , the air conditioning apparatus  10  according to the present embodiment operates, when the outside air temperature is low, the front air conditioning unit  20  to open the first inside air passage  21   a   1  and the second inside air passage  21   a   2  of the front air conditioning unit  20  such that the inside air is made to pass through the heater  27 . This makes it possible to increase the volume of heated inside air supplied to the cabin by the air conditioning apparatus  10  according to the present embodiment. In such an air conditioning apparatus  10  according to the present embodiment, when the outside air temperature is low, the heater  27  of the front air conditioning unit  20  can help defrost the evaporator  37   b  of the seat air conditioning unit  30 . Because of this, the air conditioning apparatus  10  according to the present embodiment differs from the air conditioning apparatus  110  according to the comparative embodiment and can prevent the heat exchanger  37 , even when the outside air temperature is low, from malfunctioning due to the frosted evaporator  37   b  of the seat air conditioning unit  30 . 
     &lt;Main Features of Air Conditioning System According to Present Embodiment&gt; 
     (1) As shown in  FIG. 2 , the air conditioning apparatus  10  (vehicle air conditioning apparatus) according to the present embodiment includes a plurality of seat air conditioning units  30  for cooling or heating which is selectively performed per corresponding seat  104  among a plurality of seats  104  installed in the cabin  103 . In addition, the air conditioning apparatus  10  is provided with a plurality of exhaust ducts  62 FR,  62 FL,  62 RR, and  62 RL for discharging, outside the cabin  103 , part of air used in the seat air conditioning units  30 . At least part of the plurality of exhaust ducts  62 FR,  62 FL,  62 RR, and  62 RL is merged. 
     In such an air conditioning apparatus  10  according to the present embodiment, the ducts  60  (in particular, exhaust ducts  62 ) can be simplified. In addition, the air conditioning apparatus  10  can gather and discharge through exhaust ducts  62 , part of air (outside air), together with heat, used in the seat air conditioning units  30  (that is, heat of each seat air conditioning unit  30  can be drained together). Also, in the air conditioning apparatus  10 , the size of each seat air conditioning unit  30  can be made compact. Thus, in the air conditioning apparatus  10 , the degree of design freedom can be enhanced. 
     (2) As shown in  FIG. 2 , the air conditioning apparatus  10  (vehicle air conditioning apparatus) according to the present embodiment is provided with a plurality of air supply ducts  61 FR,  61 FL,  61 RR, and  61 RL for supplying outside air to the seat air conditioning units  30 . At least part of the plurality of air supply ducts  61 FR,  61 FL,  61 RR, and  61 RL is merged. 
     In such an air conditioning apparatus  10  according to the present embodiment, the ducts  60  (in particular, air supply ducts  61 ) can be simplified. In addition, the air conditioning apparatus  10  can use the air supply ducts  61  to supply outside air for heat exhaust to each seat air conditioning unit  30  (i.e., air is together supplied to each seat air conditioning unit  30 ). In such an air conditioning apparatus  10 , the front air conditioning unit  20 , the seat air conditioning units  30 , and the rear blowing units  40  can share a fan for outside air heat exchanger. As a result, in the air conditioning apparatus  10 , the fan (blowing fan) for the outside air heat exchanger of each seat air conditioning unit  30  can be omitted (see  FIG. 5B ). For instance, when the air conditioning apparatus  10  has four seat air conditioning units  30 , four fans (blowing fans) for outside air heat exchanger can be omitted. Due to this, in the air conditioning apparatus  10 , the size and cost of each seat air conditioning unit  30  can be improved. Also, in the air conditioning apparatus  10 , vent holes between each heat exchanger and the outside of the cabin may be unified, so that the number of vehicle vent holes can be reduced. Thus, in the air conditioning apparatus  10 , a risk of water infiltration and/or noise can be decreased. Further, in the air conditioning apparatus  10 , the surrounding members can be simplified. 
     (3) As shown in  FIG. 5B , in the air conditioning apparatus  10  (vehicle air conditioning apparatus) according to the present embodiment, it is preferable that each seat air conditioning unit  30  has the following configuration. Specifically, the air conditioning apparatus  10  has the condenser  37   a  for condensing a refrigerant and the evaporator  37   b  for evaporating a refrigerant. In addition, the air conditioning apparatus  10  has passages for flowing outside air and inside air (the first inside air passage  31   a   1 , the second inside air passage  31   a   2 , the first outside air passage  31   b   1 , and the second outside air passage  31   b   2 ). Further, the air conditioning apparatus  10  has a passage switching device  34  (switching doors  34   a ,  34   b ,  34   c , and  34   d ) for switching between passages such that during cooling operation, outside air is guided in a direction toward the condenser  37   a  and during heating operation, outside air is guided in a direction toward the evaporator  37   b.    
     In such an air conditioning apparatus  10  according to the present embodiment, even when the outside air temperature is low and the capacity of each seat air conditioning unit  30  is insufficient, the evaporator  37   b  of each seat air conditioning unit  30  is defrosted, so that heat absorption efficiency of the heat exchanger  37  of each seat air conditioning unit  30  can be increased. 
     (4) As shown in  FIG. 5B , in the air conditioning apparatus  10  (vehicle air conditioning apparatus) according to the present embodiment, it is preferable that each seat air conditioning unit  30  has the following configuration. Specifically, the air conditioning apparatus  10  has the first outside air passage  31   b   1  through which outside air flows into the condenser  37   a  and the second outside air passage  31   b   2  through which outside air flows into the evaporator  37   b . In addition, the air conditioning apparatus  10  has the first inside air passage  31   a   1  through which inside air flows into the condenser  37   a  and the second inside air passage  31   a   2  through which inside air flows into the evaporator  37   b . Here, in the air conditioning apparatus  10 , the air inlet of the first outside air passage  31   b   1  and the air inlet of the second outside air passage  31   b   2  are merged. In addition, in the air conditioning apparatus  10 , the air outlet of the first outside air passage  31   b   1  and the air outlet of the second outside air passage  31   b   2  are merged. Further, in the air conditioning apparatus  10 , the air inlet of the first inside air passage  31   a   1  and the air inlet of the second inside air passage  31   a   2  are merged. 
     In such an air conditioning apparatus  10  according to the present embodiment, the outside air-use air inlets are merged, the outside air-use air outlets are merged, and the inside air-use air inlets are merged, so that the size of each seat air conditioning unit  30  can be made compact. Thus, in the air conditioning apparatus  10 , the degree of design freedom can be enhanced. 
     (5) As shown in  FIGS. 8 and 9 , it is preferable that the air conditioning apparatus  10  (vehicle air conditioning apparatus) according to the present embodiment has the following configuration. Specifically, in the air conditioning apparatus  10 , the first outside air passage  31   b   1  and the first inside air passage  31   a   1  share a common space around the condenser  37   a . In addition, in the air conditioning apparatus  10 , the second outside air passage  31   b   2  and the second inside air passage  31   a   2  share a common space around the evaporator  37   b . As shown in  FIG. 8 , the passage switching device  34  (switching doors  34   a ,  34   b ,  34   c , and  34   d ) can be used to switch between passages such that during cooling operation, outside air passes through the first outside air passage  31   b   1  and inside air passes through the second inside air passage  31   a   2 . As shown in  FIG. 9 , the passage switching device  34  (switching doors  34   a ,  34   b ,  34   c , and  34   d ) can be used to switch between passages such that during heating operation, outside air passes through the second outside air passage  31   b   2  and inside air passes through the first inside air passage  31   a   1 . 
     Such a seat air conditioning unit  30  of the air conditioning apparatus  10  according to the present embodiment has a simple structure and can then implement outside air heat exchange and inside air heat exchange. Thus, in the air conditioning apparatus  10 , the degree of design freedom can be enhanced. 
     As described above, the air conditioning apparatus  10  according to the present embodiment makes it possible to reduce the number of blowing fans (see  FIG. 5B ). 
     The present invention is not limited to the above embodiment(s) and can be variously modified and/or altered without departing from the spirit of the present invention. 
     For instance, the number of the seat air conditioning units  30  is not limited to four and may be two or more. 
     In addition, for instance, in the above embodiment(s), exemplified is the case where the seats  104  are provided at two rows: the front row and the rear low. However, the number of rows for the seats  104  may be three or more. In this case, the linear pipe arranged at substantially the middle branches into the air supply ducts  61  such that the number of branches is increased by the number of the seat air conditioning units  30  installed at the respective seats  104  at or after the third row and each air supply duct  61  is connected to the corresponding seat air conditioning unit  30 . In addition, the seat air conditioning units  30  installed at the respective seats  104  at or after the third row each use substantially the same air supply duct  61  and exhaust duct  62  as of the seat air conditioning units  30  at the first or second row to be connected to the front air conditioning unit  20  and the corresponding rear blowing unit  40 , respectively. 
     REFERENCE SIGNS LIST 
       10  Air conditioning apparatus (vehicle air conditioning apparatus) 
       20  Front air conditioning unit 
       21  Inside/outside air switching damper 
       21   a   1  First inside air passage 
       21   a   2  Second inside air passage 
       21   b  Outside air passage 
       24   a ,  24   b ,  24   c  ( 24 ) Switching door (switching device) 
       25  Filter 
       26  ( 26   a ,  26   b ) Fan 
       27  Heater 
       27   a  Heater core 
       27   b  Heat pipe 
       30  ( 30 FR,  30 FL,  3 ORR,  3 ORL) Seat air conditioning unit 
       31  Inside/outside air switching damper 
       31   a   1  First inside air passage (flow path) 
       31   a   2  Second inside air passage (flow path) 
       31   b   1  First outside air passage (flow path) 
       31   b   2  Second outside air passage (flow path) 
       32   a ,  32   b  Air inlet 
       34   a ,  34   b ,  34   c ,  34   d  ( 34 ) Switching door (passage switching device) 
       36  Fan 
       37  Heat exchanger 
       37   a  Condenser 
       37   b  Evaporator 
       40  ( 40 R,  40 L) Rear blowing unit 
       41   b  Outside air passage 
       46  Fan 
       50   a  Introduction port 
       50   b  Vent hole 
       60  Duct 
       61  ( 61 R,  61 L) Air supply duct 
       62   a  ( 62   aR ,  62   aL ),  62   b  ( 62   bR ,  62   bL ) Exhaust duct 
       63  ( 63 R,  63 L) Ventilation duct 
       71  Condenser air passage 
       71   a  Inside air inlet of the condenser air passage  71   
       71   b  Inside air outlet of the condenser air passage  71   
       71   c  Outside air inlet of the condenser air passage  71   
       71   d  Outside air outlet of the condenser air passage  71   
       72  Evaporator air passage 
       72   a  Outside air inlet of the evaporator air passage  72   
       72   b  Outside air outlet of the evaporator air passage  72   
       72   c  Inside air inlet of the evaporator air passage  72   
       72   d  Inside air outlet of the evaporator air passage  72   
       100  Vehicle 
       102  Front section 
       103  Cabin 
       104  Seat