Abstract:
Disclosed therein is an air conditioner for a vehicle, which includes an evaporator and a storage tank getting in surface contact with each other, thereby doubling a cold storage effect by directly transferring cold air of the evaporator to the storage tank in a cooling mode, maximizing the cold storage effect because condensate water generated from the surface of the evaporator additionally cools the surface of the storage tank, and effectively enhancing heat-exchanging performance without increasing capacity of the storage tank. The air conditioner further includes heat-exchanging means mounted inside the storage tank so as to enhance the heat exchange performance of a heat carrier more.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an air conditioner for a vehicle, and more particularly, to an air conditioner for a vehicle, which includes and evaporator and a storage tank storing a heat carrier exchanging heat with the evaporator so as to accumulate cold air or warm air. 
         [0003]    2. Background Art 
         [0004]    Recently, releases of hybrid cars or idle-stop cars have been rapidly increased as measures for improvement of fuel efficiency and as countermeasures on environmental pollution according to the exhaust gas emission regulations. 
         [0005]    In case of the hybrid cars or the idle-stop cars, engines are automatically stopped when they come to stop due to waiting for signal, but they have a problem in that a compressor for a cooling cycle connected to the engine is stopped, and it causes a lack of a heat source for cooling, and thus, comfort inside the cars is deteriorated. 
         [0006]    In order to solve the above problem, there have been many studies on an air conditioner which has a cold storage function inside the air conditioner or has a battery separately mounted so as to operate the air conditioner by the battery when the engine is stopped for a long time. 
         [0007]      FIG. 1  is a schematic diagram of a conventional air conditioner for a vehicle. 
         [0008]    As shown in  FIG. 1 , the conventional air conditioner for the vehicle includes an air-conditioning case  1 , an air blower  2   a,  an evaporator  3   a  and a heater core  4 , a temperature-adjusting door  5 , and a storage tank  6 . 
         [0009]    The air-conditioning case  1  includes: an indoor and outdoor air converting door  1   a  mounted at an inlet for allowing an inflow of the indoor air and the outdoor air; and vents  1   e,    1   f  and  1   g  mounted at an outlet and adjusted in the degree of opening by doors  1   b ,  1   c  and  1   d . The air blower  2   a  is mounted at the inlet of the air-conditioning case  1 , and the evaporator  3   a  and the heater core  4  are mounted in an inside flow channel of the air-conditioning case  1  in order. 
         [0010]    The temperature-adjusting door  5  adjusts the degree of opening of a cold air passageway P 1  and a warm air passageway P 2  of the air-conditioning case  1 , and the storage tank  6  is arranged at the downstream side of the evaporator  3   a  in order to accumulate cold air passing through the evaporator  3   a.    
         [0011]    In the conventional air conditioner for the vehicle having the above structure, when a compressor (not shown) interlocked with the engine is operated, a refrigerant cycle including the evaporator  3   a  is also operated and the indoor air and the outdoor air introduced through the indoor and outdoor air converting door  1   a  are heat-exchanged in the evaporator  3   a  and discharged to the vents  1   e,    1   f  and  1   g,  and during the above process, cold air heat-exchanged in the evaporator  3   a  is accumulated in the storage tank  6 . 
         [0012]    In the above state, in the case of the hybrid cars which stop operation of the engine for a short period of time like when the cars stop by waiting for signal or like when the cars are stopped due to traffic jam, the operation of the refrigerant cycle is stopped by the stop of the engine, and thus, cold air accumulated in the storage tank  6  is discharged so as to cool the inside of the car. 
         [0013]    The conventional air conditioner for the vehicle needs the storage tank  6  of a large capacity in order to sufficiently carry out the cold storage function. However, if capacity of the storage tank  6  is increased, the air conditioner occupies a large installation space and the entire load and volume of the air conditioner are also increased. 
       SUMMARY OF THE INVENTION 
       [0014]    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 an air conditioner for a vehicle, which includes an evaporator and a storage tank getting in surface contact with each other so as to maximize a cold storage effect and to effectively enhance a heat exchange performance without increasing capacity of the storage tank. 
         [0015]    It is another object of the present invention to provide an air conditioner for a vehicle, which additionally has heat-exchanging means mounted inside the storage tank so as to enhance the heat exchange performance of a heat carrier more. 
         [0016]    To accomplish the above object, according to the present invention, there is provided an air conditioner for a vehicle including: an air-conditioning case; an evaporator and a heater core mounted inside the air-conditioning case along an air flow direction in order; a flow rate control valve mounted between inlet and outlet pipes of the heater core and a cooling water pipe of an engine for controlling a flow rate of cooling water circulating from the engine to the heater core; a circulation pump for circulating the cooling water contained inside the heater core, wherein the cooling water contained in the heater core is used as a heat carrier for cold storage or heat storage; and a storage tank on which the evaporator is mounted, the storage tank having a surface contact part for allowing the evaporator to be in surface contact with the storage tank so as to carry out heat exchange of the heat carrier. 
         [0017]    According to the exemplary embodiments of the present invention, because the evaporator is mounted on the upper portion of the storage tank, the air conditioner can double a cold storage effect by directly transferring cold air of the evaporator to the storage tank in a cooling mode, and maximize the cold storage effect since condensate water generated from the surface of the evaporator additionally cools the surface of the storage tank. 
         [0018]    Moreover, because the storage tank includes the partition part disposed therein, the air conditioner can effectively enhance the heat exchange performance without increasing the volume of the storage tank. 
         [0019]    Furthermore, the air conditioner for the vehicle according to the exemplary embodiments of the present invention can control flow rate and flow speed of the heat carrier through the partition part formed inclinedly, thereby enhancing the heat exchange performance. 
         [0020]    Additionally, the air conditioner for the vehicle according to the exemplary embodiments of the present invention can maximize the heat exchange performance of the storage tank through the baffle having a specific form. 
         [0021]    In addition, because the refrigerant pipe of the outlet side of the evaporator is inserted into the storage tank to pass through the storage tank, the cold refrigerant flowing in the refrigerant pipe of the outlet side of the evaporator exchanges heat with the cooling water (heat carrier) contained in the storage tank, such that the cooling water of the storage tank is more rapidly cooled so as to enhance the cold storage efficiency. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    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: 
           [0023]      FIG. 1  is a schematic diagram of a conventional air conditioner for a vehicle; 
           [0024]      FIG. 2  is a schematic diagram of an air conditioner for a vehicle according to a first preferred embodiment of the present invention; 
           [0025]      FIG. 3  is a perspective view of a storage tank of the air conditioner for the vehicle according to the first preferred embodiment of the present invention; 
           [0026]      FIG. 4  is a side sectional view of the storage tank of the air conditioner for the vehicle according to the first preferred embodiment of the present invention; 
           [0027]      FIG. 5  is a plan view showing the inside of the storage tank of the air conditioner for the vehicle according to the first preferred embodiment of the present invention; 
           [0028]      FIG. 6  is a side sectional view of a storage tank according to a second preferred embodiment of the present invention; 
           [0029]      FIG. 7  is a plan view showing the inside of the storage tank according to the second preferred embodiment of the present invention; 
           [0030]      FIG. 8  is a plan view showing the inside of a storage tank according to a modification of  FIG. 7 ; 
           [0031]      FIG. 9  is a plan view showing the inside of a storage tank according to another modification of  FIG. 7 ; 
           [0032]      FIG. 10  is a perspective view showing a state where heat-exchanging means is mounted inside the storage tank according to the present invention; 
           [0033]      FIG. 11  is a plan view showing the inside of the storage tank of  FIG. 10 ; 
           [0034]      FIG. 12  is a sectional view showing a state where an engine is stopped during a cooling mode in the air conditioner for the vehicle according to the second preferred embodiment of the present invention; 
           [0035]      FIG. 13  is a sectional view showing a heating mode in the air conditioner for the vehicle according to the second preferred embodiment of the present invention; and 
           [0036]      FIG. 14  is a sectional view showing a state where the engine is stopped during the heating mode in the air conditioner for the vehicle according to the second preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0037]    Reference will be now made in detail to the preferred embodiment of the present invention with reference to the attached drawings. 
         [0038]      FIG. 2  is a schematic diagram of an air conditioner for a vehicle according to a first preferred embodiment of the present invention,  FIG. 3  is a perspective view of a storage tank of the air conditioner for the vehicle according to the first preferred embodiment of the present invention,  FIG. 4  is a side sectional view of the storage tank of the air conditioner for the vehicle according to the first preferred embodiment of the present invention, and  FIG. 5  is a plan view showing the inside of the storage tank of the air conditioner for the vehicle according to the first preferred embodiment of the present invention. 
         [0039]    As shown in  FIGS. 2 to 5 , the air conditioner for the vehicle according to the first preferred embodiment of the present invention includes an air-conditioning case  20 , an evaporator  24  and a heater core  29 , a flow rate control valve  550 , a circulation pump  190 , and a storage tank  27 . 
         [0040]    The air-conditioning case  20  includes an air inflow port  11  formed at an inlet, a plurality of air outflow ports formed at an outlet, and an air passageway formed therein for communicating the air inflow port  11  with the air outflow ports. In this instance, air outflow ports respectively have a defrost vent  12  for discharging air toward a front window of the vehicle, a face vent  13  for discharging air toward a front seat passenger&#39;s face, and floor vents  14   a  and  14   b  for discharging air toward the passenger&#39;s feet. Moreover, the defrost vent  12 , the face vent  13  and the floor vents  14   a  and  14   b  are respectively opened and closed by mode doors  15 ,  16  and  17 . 
         [0041]    The evaporator  24  and the heater core  29  are mounted in an inside flow channel of the air-conditioning case  20  in order. 
         [0042]    In a cooling mode, when a compressor (not shown) is operated, refrigerant circulates the compressor, a condenser (not shown), an expansion valve (not shown) and the evaporator  24 , and during the above process, air passing through the evaporator  24  is cooled by being heat-exchanged with cold refrigerant located inside the evaporator  24 , and then, is discharged to the inside of the vehicle through the air outflow ports of the air-conditioning case  20 , such that cooling is achieved. 
         [0043]    Furthermore, the heater core  29  includes a pair of tanks (not shown), a plurality of tubes (not shown) for connecting the tanks, radiation fins (not shown) interposed between the tubes, and inlet and outlet pipes  291  and  292  respectively connected to the tanks. In this instance, the inlet and outlet pipes  291  and  292  of the heater core  29  are extendably mounted toward an engine  560  of the vehicle, and are communicatably connected with cooling water pipes  561  of the engine  560 . Finally, hot cooling water heated from the engine  560  at the time of a start of the engine  560  circulates the heater core  29 , and then, is returned to the engine  560 . During the above process, air passing through the heater core  29  is heated by being heat-exchanged with the hot cooling water of the heater core  29 , and then, is discharged to the inside of the vehicle through the air outflow ports of the air-conditioning case  20 , such that heating is achieved. 
         [0044]    The flow rate control valve  550  is mounted between the inlet and outlet pipes  291  and  292  of the heater core  29  and the cooling water pipes  561  of the engine  560  in order to control a flow rate of the cooling water circulating from the engine  560  to the heater core  29 . In this instance, a temperature-adjusting door is mounted in front of the heater core  29  in order to control a mixed amount of cold air passing through the evaporator and warm air passing through the heater core  29 , so that temperature of air discharged to the inside of the vehicle can be adjusted. The flow rate control valve  550  may be in the form of a four way directional valve which can selectively bypass or communicate the cooling water circulating from the engine  560  to the heater core  29 . Detailed description of a structure of the flow rate control valve  550  will be omitted, and the operation of the flow rate control valve  550  will be described in detail later. 
         [0045]    The circulation pump  190  serves to circulate the cooling water of the storage tank  27  to the heater core  29  when the flow rate control valve  550  blocks the cooling water supplied to the heater core  29 . 
         [0046]    The storage tank  27  is mounted on a cooling water circulation line circulating the heater core  29  in order to carry out cold storage or heat storage. The evaporator  24  is mounted on the upper portion of the storage tank  27 . Additionally, the storage tank  27  has a surface contact part  130  which is in surface contact with the evaporator  24  so as to carry out heat-exchange with a heat carrier. 
         [0047]    That is, the storage tank  27  carries out cold storage or heat storage to the cooling water of the storage tank  27  in the cooling mode or in the heating mode, and circulates the cooling water cold-stored or heat-stored inside the storage tank  27  so as to prevent temperature of the discharged air of the air-conditioning case  20  from being suddenly changed when the engine is in a stop state. 
         [0048]    Moreover, because the evaporator  24  is mounted on the upper portion of the storage tank  27 , in the cooling mode, cold air of the evaporator  24  is directly transferred to the storage tank  27  so as to double the cold storage effect, and condensate water generated from the surface of the evaporator  24  additionally cools the surface of the storage tank  27  so as to maximize the cold storage effect. 
         [0049]    Furthermore, the air-conditioning case  20  includes a bypass passageway  25   a  formed above the upper portion of the heater core  29  inside the air-conditioning case  20  for bypassing some of the air passing through the evaporator  24 , and a bypass door  25  for controlling the degree of opening is mounted in the bypass passageway  25   a.  The bypass door  25  selectively opens and closes the bypass passageway  25   a  according to conditions of the vehicle. Finally, in the initial cooling mode, when the bypass passageway  25   a  is opened by the bypass door  25 , some of the air cooled in the evaporator  24  passes through the heater core  29 , but some of the cooled air bypasses the heater core  29  through the bypass passageway  25   a  so as to enhance a rapid action for the maximum cooling. The bypass door  25  opens the bypass passageway  25   a  just in the cooling mode during the operation of the engine  560 , but closes the bypass passageway  25   a  in the heating mode and when the engine  560  is stopped in the cooling and heating modes during the operation of the engine  560 . 
         [0050]    However, besides the above-mentioned structure, the air conditioner for the vehicle according to the preferred embodiment of the present invention may have the form of the air conditioner installed in electric vehicles or one of other forms. 
         [0051]    Now, in relation with a contact structure between the storage tank  27  and the evaporator  24  and an internal structure of the storage tank  27 , the structure of the air conditioner for the vehicle according to the preferred embodiment of the present invention will be described in more detail. 
         [0052]    That is, the storage tank  27  includes a surface contact part  130  and a plurality of partition parts  150 . The storage tank  27  may have just one partition part  150 , but, in this preferred embodiment, a plurality of the partition parts  150  are disposed in the storage tank  27 . 
         [0053]    The surface contact part  130  is in surface contact with the evaporator  24  in order to carry out heat exchange of the heat carrier (cooling water, hereinafter called ‘heat carrier’). 
         [0054]    The partition parts  150  are formed inside the storage tank  27  to form a flow channel of the heat carrier. The partition parts  150  functions to enhance the heat-exchange performance of the heat carrier. 
         [0055]    In other words, the partition parts  150  are extended from the bottom surface to the top surface inside the storage tank  27 , are interdigitated at both sides of the storage tank  27  to form a zigzag flow channel of the heat carrier. Therefore, the heat carrier flowing inside the storage tank  27  is increased in channel flow resistance during the heat exchange with the evaporator  24  through the surface contact part  130  but is reduced in flow rate, and thus, a congestion period of time of the heat carrier becomes longer near the surface contact part  130 . 
         [0056]    As described above, because the partition parts  150  are formed inside the storage tank  27  at the same time with the surface contact between the evaporator  24  and the storage tank  27 , the heat exchange performance of the storage tank  27 . 
         [0057]    In this instance, the storage tank  27  has an approximately cuboid form in which a space part  160  is formed, and the surface contact part  130  is formed by the upper portion of the storage tank  27  dented inwardly. The storage tank  27  includes: an inlet  141  for introducing the heat carrier into the storage tank  27 ; and an outlet  142  for discharging the heat carrier to the outside of the storage tank  27 . 
         [0058]    The evaporator  24  is inserted into the dented portion of the surface contact part  130 , and hence, is in a direct surface contact with the sides and the bottom surface of the dented portion of the surface contact part  130 . Therefore, the heat carrier inserted into the storage tank  27  through the inlet  141  flows along the flow channel of the zigzag form formed by the partition parts  150 , and exchanges heat with the evaporator  24  through the sides and the bottom surface of the dented portion of the surface contact part  130 . 
         [0059]    Through the above-mentioned structure, the storage tank  27  with a relatively small volume can effectively exchange heat with the evaporator  24 , and can reduce manufacturing costs because it does not need additional ducts or pipes. 
         [0060]    Moreover, at least one of the partition parts  150  is arranged directly beneath the surface contact part  130 . 
         [0061]    By the partition part  150  arranged directly beneath the surface contact part  130 , at least one curved section where the heat carrier flows is formed near the surface contact part  130  which is in contact with the evaporator  24 , and such a curved section increases the flow channel resistance of the heat carrier so as to effectively promote the heat exchange of the storage tank  27 . 
         [0062]      FIG. 6  is a side sectional view of a storage tank according to a second preferred embodiment of the present invention, and  FIG. 7  is a plan view showing the inside of the storage tank according to the second preferred embodiment of the present invention. 
         [0063]    Referring to  FIGS. 6 and 7 , a storage tank  327  includes a surface contact part  230  and a plurality of partition parts  250 . The storage tank  327  may have just one partition part  250 , but, in this preferred embodiment, a plurality of the partition parts  250  are disposed in the storage tank  327 . 
         [0064]    The surface contact part  230  is in surface contact with the evaporator  224  in order to carry out heat exchange of the heat carrier, such as water. 
         [0065]    The partition parts  250  are formed inside the storage tank  327  to form a flow channel of the heat carrier. The partition parts  250  functions to enhance the heat-exchange performance of the heat carrier. 
         [0066]    In other words, the partition parts  250  are extended from the bottom surface to the top surface inside the storage tank  327 , are interdigitated at both sides of the storage tank  327  to form a zigzag flow channel of the heat carrier. Therefore, the heat carrier flowing inside the storage tank  327  is increased in channel flow resistance during the heat exchange with the evaporator  224  through the surface contact part  230  but is reduced in flow rate, and thus, a congestion period of time of the heat carrier becomes longer near the surface contact part  230 . 
         [0067]    As described above, because the partition parts  250  are formed inside the storage tank  327  at the same time with the surface contact between the evaporator  224  and the storage tank  327 , the heat exchange performance of the storage tank  327 . 
         [0068]    In this instance, the storage tank  327  has an approximately cuboid form in which a space part  260  is formed, and the surface contact part  230  is formed by the upper portion of the storage tank  327  dented inwardly. The storage tank  327  includes: an inlet  241  for introducing the heat carrier into the storage tank  327 ; and an outlet  242  for discharging the heat carrier to the outside of the storage tank  327 . 
         [0069]    The evaporator  224  is inserted into the dented portion of the surface contact part  330 , and hence, is in a direct surface contact with the sides and the bottom surface of the dented portion of the surface contact part  230 . Therefore, the heat carrier inserted into the storage tank  327  through the inlet  241  flows along the flow channel of the zigzag form formed by the partition parts  250 , and exchanges heat with the evaporator  324  through the sides and the bottom surface of the dented portion of the surface contact part  230 . 
         [0070]    In this instance, the partition parts  250  are formed inclinedly in a direction of the flow channel of the heat carrier (a flow direction of the heat carrier). In other words, the partition parts  250  arranged at both sides of the surface contact part  230  are respectively inclined toward the partition parts  250  arranged directly beneath the surface contact part  230 , such that a cross sectional area of the flow channel of the heat carrier becomes narrower near the surface contact part  230 . 
         [0071]    As described above, as the cross sectional area of the flow channel of the heat carrier becomes narrower, the heat carrier flowing in the narrower flow channel section is increased in flow channel resistance and is reduced in flow rate inside the storage tank  327 , such that the heat exchange performance of the storage tank  327  is maximized. 
         [0072]    Moreover,  FIG. 8  is a plan view showing the inside of a storage tank according to a modification of  FIG. 7 . 
         [0073]    As shown in  FIG. 8 , the storage tank  327  further includes at least one baffle  251 . 
         [0074]    The baffle  251  protrudes from the partition part  250 , and it is preferable that the baffle  251  be arranged near the surface contact part  230 . The baffle  251  increases the flow channel resistance of the heat carrier more so as to reduce the flow rate of the heat carrier inside the storage tank  327  more effectively, such that the heat exchange performance of the storage tank  327  is maximized more. 
         [0075]    In this instance, the baffle  251  extends inclinedly along the flow direction of the heat carrier from the side wall of the partition part  250 . Therefore, an eddy is generated at a rear space  255  formed between the partition part  250  and the baffle  251  when the heat carrier flows, and the eddy helps enhancement of the heat exchange performance of the storage tank  327  in the vicinity of the surface contact part  230 . 
         [0076]    In the meantime,  FIG. 9  is a plan view showing the inside of a storage tank according to another modification of  FIG. 7 . 
         [0077]    As shown in  FIG. 9 , the baffle  251  may be formed in a zigzag. 
         [0078]    The zigzag-formed baffle  251  helps reduction of the flow rate of the heat carrier, and enhances the heat exchange performance of the storage tank  327  because eddy is generated at concave portions  255  formed between valleys of the baffle  251  while the heat carrier flows. 
         [0079]      FIG. 10  is a perspective view showing a state where heat-exchanging means is mounted inside the storage tank according to the present invention, and  FIG. 11  is a plan view showing the inside of the storage tank of  FIG. 10 . 
         [0080]      FIGS. 10 and 11  illustrate an example that heat-exchanging means  22  is applied to the inside of the storage tank  27  according to the preferred embodiment of the present invention, and it may be applied not only to this preferred embodiment but also all preferred embodiments of the present invention. 
         [0081]    As shown in  FIGS. 10 and 11 , the heat-exchanging means  22  is mounted inside the storage tank  27  in order to exchange heat between refrigerant circulating the evaporator  24  and the heat carrier (cooling water) stored in the storage tank  27 . 
         [0082]    The heat-exchanging means  22  is constructed in such a manner that a refrigerant pipe connected to the evaporator  24 , out of refrigerant pipes which connect the compressor, the condenser, the expansion valve and the evaporator  24  with one another, is mounted to pass through the storage tank  27 . 
         [0083]    Here, the refrigerant pipe connected to the evaporator  24  includes: an inlet pipe  24   a  for introducing refrigerant into the evaporator  24 ; and an outlet pipe  24   b  for discharging refrigerant to the outside. 
         [0084]    In this instance, it is preferable that the refrigerant pipe passing through the inside of the storage tank  27  be the outlet pipe  24   b  of the evaporator  24 . 
         [0085]    That is, in the cooling mode, the refrigerant flowing in the outlet pipe  24   b  of the evaporator  24  is a cold refrigerant of low temperature and low pressure. 
         [0086]    Therefore, because a partial section of the outlet pipe  24   b  of the evaporator  24  is inserted into the storage tank  27  to pass through the storage tank  27 , the heat carrier of the storage tank  24  exchanges heat with the cold refrigerant flowing in the outlet pipe  24   b  of the evaporator  24 , such that the cooling water of the storage tank  24  is more rapidly cooled so as to enhance the cold storage efficiency. 
         [0087]    Moreover, the outlet pipe  24   b  of the evaporator  24 , which is the refrigerant pipe passing through the storage tank  27  is formed along the flow channel of the heat carrier inside the storage tank  27 . Therefore, the flow channel resistance of the heat carrier is increased more by the outlet pipe  24   b  formed along the flow channel of the heat carrier inside the storage tank  27 , and thus, the heat carrier can flow in a limited space of the storage tank  27  as long as possible and a heat exchange period of time between the outlet pipe  24   b  and the heat carrier becomes longer, such that the heat exchange performance is enhanced. 
         [0088]    Meanwhile, the partial section of the outlet pipe  24   b  of the evaporator  24  inserted into the storage tank  27  is bent in a zigzag form so as to increase a heat exchange area with the heat carrier and to increase the flow channel resistance of the heat carrier more, such that the flow rate is reduced. 
         [0089]    Additionally, as shown in  FIGS. 10 and 1 , a drain hole  135  is formed in the surface contact part  130  in order to smoothly drain condensate water generated in the evaporator  24 . 
         [0090]    The drain hole  135  is formed to vertically penetrate the storage tank  27  from the bottom surface of the surface contact part  130 . In this instance, the drain hole  135  is partitioned from the inside of the storage tank  27 . 
         [0091]    Therefore, the condensate water generated in the evaporator  24  and dropping down into the surface contact part  13  can be drained smoothly through the drain hole  135 . 
         [0092]      FIG. 12  is a sectional view showing a state where an engine is stopped during a cooling mode in the air conditioner for the vehicle according to the second preferred embodiment of the present invention,  FIG. 13  is a sectional view showing a heating mode in the air conditioner for the vehicle according to the second preferred embodiment of the present invention, and  FIG. 14  is a sectional view showing a state where the engine is stopped during the heating mode in the air conditioner for the vehicle according to the second preferred embodiment of the present invention. 
         [0093]    Referring to  FIGS. 2 and 12  to  14 , the operation of the air conditioner for the vehicle according to the preferred embodiments of the present invention will be described. 
         [0094]    A. Cooling Mode (See  FIG. 2 ) 
         [0095]    In the cooling mode, when the flow rate control valve  550  perfectly blocks cooling water supplied from the engine  560  to the heater core  29 , the cooling water supplied from the engine  560  makes a U-turn to return to the engine  560 . Moreover, the bypass door  25  opens the bypass passageway  25   a,  and the circulation pump  190  is operated. 
         [0096]    Therefore, the air introduced through the air inflow port  11  of the air-conditioning case  20  is cooled while passing through the evaporator  24 , and some of the cold air bypasses the heater core  29  through the bypass passageway  25   a,  and some of the cold air passes the heater core  29  and is discharge to the inside of the vehicle through the air outflow port opened by the mode door according to air-conditioning modes, such that cooling is achieved. 
         [0097]    In the above process, the cold air cooled while passing through the evaporator  24  cools the cooling water of the heater core  29  while passing through the heater core  29 , and thus, the cooling water is cooled. While the cold cooling water in the heater core  29  circulates to the storage tank  27 , the storage tank  27  carries out cold storage. 
         [0098]    In this instance, because the evaporator  24  mounted on the upper portion of the storage tank  27  gets in surface contact with the storage tank  27 , the cold air of the evaporator  27  is directly transferred to the cooling water of the storage tank  27  so as to double the cold storage effect, and the condensate water generated from the surface of the evaporator  27  additionally cools the surface of the storage tank  27  so as to maximize the cold storage effect. 
         [0099]    B. At the Time of Engine Stop in Cooling Mode (See  FIG. 12 ) 
         [0100]    When the engine  560  of the vehicle is stopped by waiting for signal or by a stop signal while the vehicle travels in the cooling mode, the compressor is stopped and the air conditioner is turned off. In this instance, because temperature of the evaporator  24  rises, temperature of the air passing through the evaporator  24  may rapidly rise. In order to prevent such a rapid rise of temperature, the bypass door  25  closes the bypass passageway  25   a  so that the entire air passing through the evaporator  24  passes the heater core  29 , and the circulation pump  190  operates continuously so as to circulate the cold cooling water of the storage tank  27  to the heater core  29 . 
         [0101]    Therefore, because the elevated temperature of the air while passing through the evaporator  24  drops by the cold cooling water of the heater core  29 , the air conditioner according to the preferred embodiment of the present invention can prevent a rapid rise of temperature of the air discharged to the inside of the vehicle, and thus, can remove passengers&#39; displeasure. 
         [0102]    C. Heating Mode (See  FIG. 13 ) 
         [0103]    In the heating mode, the flow rate control valve  550  circulates hot cooling water heated from the engine  560  to the heater core  29  and returns the cooling water to the engine  560 , and the bypass door  25  closes the bypass passageway  25   a.  Moreover, in the heating mode while the engine  560  is operated, the circulation pump  190  is in a stopped condition, and the cooling water circulates the heat core  29  by a water pump (not shown) of the engine  560 . 
         [0104]    Therefore, the air introduced through the air inflow port  11  of the air-conditioning case  20  passes through the evaporator  24 , and the air passing through the evaporator  24  is heated through heat exchange with the heater core  29  while passing through the heater core  29 , and then, is discharged to the inside of the vehicle through the air outflow portion opened by the mode door according to the air-conditioning modes, such that heating is achieved. In the above process, because the hot cooling water heated and supplied from the engine  560  is returned to the engine  560  after circulating not only to the heater core  29  but also to the storage tank  27 , the cooling water of the storage tank  27  is heated, such that the storage tank  27  can carry out heat storage. 
         [0105]    D. At the Time of Engine Stop in Heating Mode (See  FIG. 14 ) 
         [0106]    When the engine  560  of the vehicle is stopped by waiting for signal or by a stop signal while the vehicle travels in the heating mode, supply of cooling water from the engine  560  is also stopped. In this instance, because temperature of the heater core  29  drops, temperature of the air passing through the heater core  29  may rapidly drop. In order to prevent such a rapid drop of temperature, the circulation pump  190  is operated, so that the cooling water of a hot state remaining in the engine  560  even after the stop of the engine  560  and the hot cooling water stored in the storage tank  29  are circulated to the heater core  29 . 
         [0107]    Therefore, even though the engine  560  is stopped during the heating mode, because the hot cooling water stored in the engine  560  and the hot cooling water stored in the storage tank  27  circulate the heater core  29 , the air passing through the heater core  29  is discharged to the inside of the vehicle without any big change in temperature for a predetermined period of time so as to carry out heating, such that the air conditioner can prevent a rapid drop of temperature of the air discharged to the inside of the vehicle and remove the passengers&#39; displeasure. 
         [0108]    As described above, while the present invention has been particularly shown and described with reference to the example embodiments thereof, it will be understood by those of ordinary skill in the art that the above exemplary embodiments of the present invention are all exemplified and various changes, modifications and equivalents may be made therein without changing the essential characteristics and scope of the present invention. Therefore, it would be understood that the technical and protective scope of the present invention shall be defined by the technical idea and scope of the following claims.