Patent Publication Number: US-2007113527-A1

Title: Air conditioning system

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an air conditioning system, and more particularly, to an air conditioning system in which an air cleaning unit operates in association with other air conditioning devices such a heat recovery ventilator. Further, the present invention relates to an air conditioning system in which a plurality of air cleaning units is connected to a single heat recovery ventilator.  
      2. Description of the Related Art  
      When a living thing breathes in a closed space, carbon dioxide increases with time, and thus it becomes more difficult for the living thing to breathe in the closed space. Therefore, closed spaces, such as an office where a lot of people works together or the interior of a car, should be periodically ventilated. A ventilation system can be generally used for this purpose.  
      Such a ventilation system is generally installed on a floor or a ceiling to allow inflow of outdoor air and outflow of indoor air. The ventilation system is useful, particularly for places where natural ventilation is poor or many persons stay.  
      However, only an air cleaning unit or ventilation device is provided in the related art ventilation system. Therefore, for example, when the ventilation device operates in winter, heating efficiency is deteriorated since cold outdoor air is directly introduced into an indoor area.  
      Further, to control the temperatures of indoor area compartments while the ventilation device operates, an air cooling unit or a heat pumping unit should operate additionally.  
      Furthermore, since the ventilation device ventilates a number of indoor area compartments, ventilation efficiency of the device is low when the total size of the indoor area is considered.  
      In addition, to individually control the environment of each compartment of a building, a separate device such as a ventilation device or an air cooling unit should be installed in each compartment. In other words, many devices and efforts are required to individually control the environment of each compartment of a building (e.g., one compartment should be cooled while another room is just ventilated).  
     SUMMARY OF THE INVENTION  
      Accordingly, the present invention is directed to an air conditioning system that substantially obviates one or more problems due to limitations and disadvantages of the related art.  
      An object of the present invention is to provide an air conditioning system that ventilates a plurality of indoor area compartments using a single ventilation unit and thus has a high ventilation efficiency when the total volume of the indoor area is considered.  
      Another object of the present invention is to provide an air conditioning system that can individually control the environments of many indoor area compartments.  
      Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
      To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided an air conditioning system including: an air cleaning unit including a grill having a discharge grill on a side portion, a fan sucking indoor air and/or outdoor air, a filter cleaning the sucked air, and an installation case attached to one side of the grill and having a suction hole and an exhaust hole; a ventilation unit operating in association with the air cleaning unit; and a duct member connecting the air cleaning unit and the ventilation unit.  
      In another aspect of the present invention, there is provided an air conditioning system including: a ventilation unit in which indoor air and outdoor air exchange heat with each other; at least one air cleaning unit connected to the ventilation unit, the air cleaning unit including a grill having a discharge grill on a side portion, a fan sucking indoor air and/or outdoor air, a filter cleaning the sucked air sucked; a duct member connecting the air cleaning unit and the ventilation unit, the duct member including a supply duct allowing outdoor air flow and an exhaust duct allowing indoor air flow; and a diffuser connected to the ventilation unit or the duct member.  
      In a further another aspect of the present invention, there is provided an air conditioning system including: a ventilation unit allowing heat exchange between an inflow of outdoor air and an outflow of indoor air; an air cleaning unit directly or indirectly connected to the ventilation unit; and an air conditioning unit directly or indirectly connected to the ventilation unit or the air cleaning unit, the air conditioning unit including an indoor unit supplying cooled air or heated air to an indoor area and an outdoor air allowing heat exchange between outdoor air and refrigerant, wherein the air cleaning unit includes a grill having a discharge grill, a fan installed on an inner side for sucking air, a filter cleaning the sucked air, and an installation case attached to one side of the grill and having a suction hole and an exhaust hole.  
      It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:  
       FIG. 1  is a perspective view of an air cleaning unit with ventilation and air-cleaning functions according to the present invention;  
       FIG. 2  is an exploded perspective view of the air cleaning unit depicted in  FIG. 1 ;  
       FIG. 3  is a vertical sectional view of the air cleaning unit depicted in  FIG. 1 ;  
       FIG. 4  is a perspective view showing a first embodiment of an installation case according to the present invention;  
       FIG. 5  is a perspective view showing a second embodiment of the installation case according to the present invention;  
       FIG. 6  shows a first embodiment of installing the air cleaning unit in a building according to the present invention;  
       FIG. 7  is an exploded perspective view showing an air flow of the air cleaning unit in ventilation mode;  
       FIG. 8  is a bottom perspective view showing an air flow of the air cleaning unit in cleaning mode;  
       FIG. 9  shows a second embodiment of installing the air cleaning unit in a building according to the present invention;  
       FIG. 10  is a system diagram showing the air cleaning unit connected to a ventilation unit according to the present invention;  
       FIG. 11  is a sectional view showing a schematic air flow of the system shown in  FIG. 10 ;  
       FIG. 12  is an exploded perspective view of a duct member according to the present invention;  
      FIGS.  13  to  15  show air conditioning systems according to embodiments of the present invention;  
       FIG. 16  shows a block diagram of an air conditioning system according to another embodiment of the present invention;  
       FIG. 17  shows a block diagram of an air conditioning system according to another embodiment of the present invention;  
       FIGS. 18 and 19  are system diagrams of air conditioning systems according to another embodiments of the present invention;  
       FIGS. 20 and 21  are system diagrams of air conditioning systems according to another embodiments of the present invention;  
       FIG. 22  is a block diagram of an air conditioning system according to another embodiment of the present invention;  
       FIG. 23  is a block diagram of an air conditioning system according to another embodiment of the present invention; and  
       FIG. 24  is a block diagram of an air conditioning system according to another embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
       FIG. 1  is a perspective view of an air cleaning unit  10  with ventilation and air-cleaning functions according to the present invention,  FIG. 2  is an exploded perspective view of the air cleaning unit  10 , and  FIG. 3  is a vertical sectional view of the air cleaning unit  10 .  
      Referring to FIGS.  1  to  3 , the air cleaning unit  10  is designed to provide both ventilation and air cleaning. The air cleaning unit  10  includes: a front cover  11  having an air suction hole in a center portion; a cover guide  12  on which the front cover  11  is mounted; a grill  14  having cleaned air discharge holes on lateral sides and on which the cover guide  12  is slidably mounted; a filter  13  disposed in a lower portion of the grill  14  to remove impurities and odors from air; a control box  19  coupled to a lower edge of the grill  14 ; a control panel  21  detachably coupled to a lower portion of the cover guide  12 ; and a shield member  23  selectively shields screening the cleaned air discharge holes formed on the lateral sides of the grill  14 . In detail, a main printed circuit board (PCB) substrate is disposed in the control box  19  for controlling the operation of the air cleaning unit  10 , and a display PCB substrate is mounted on one side of a rear surface of the control panel  21  for display the operational state of the air cleaning unit  10 . When the air cleaning unit  10  is installed between a wall and a ceiling, the cleaned air discharge holes of the grill  14  facing the wall is screened by the shield member  23 . In this case, air is discharged through the discharge holes located on a front and an opposite side of the grill  14 . The filter  13  includes a pre filter  131  for removing floating duct particles having a relatively large size, a high efficiency particulate air (HEPA) filter  132  for removing tiny dust particles passing through the pre filter  131 , and a deodorization filter  133  for removing odors from air passing through the HEPA filter  132 .  
      The air cleaning unit  10  further includes a fan  15  disposed above the filter  13  for drawing indoor or outdoor air into the air cleaning unit  10 , a shroud  145  detachably coupled to a lower portion of the grill  14  for guiding the air drawn by the fan  15 , a fan motor  20  driving the fan  15 , and a rear panel  16  having one side connected to an exhaust duct and a supply duct. The fan motor  20  is mounted on the rear panel  16 .  
      The air cleaning unit  10  further includes a base panel  22  mounted on a top surface of the rear panel  16  for strengthen the rear panel  16 , an installation case  17  coupled to one side of the rear panel  16  for allowing the rear panel  16  to be easily connected to the exhaust duct and the supply duct, and installation bars  18  detachably coupled to a top portion of the rear panel  16  for allowing the rear panel  16  to be easily mounted on a wall or a ceiling.  
      Hereinafter, an operation of the air cleaning unit  10  will be described when the air cleaning unit  10  is installed on a ceiling according to an embodiment of the present invention.  
      When the air cleaning unit  10  is installed on a ceiling, the front cover  11  faces a floor. In this state, the fan  15  is driven by the fan motor  20  when a cleaning mode is selected. Then, indoor air is sucked by the operation of the fan  15  into the air cleaning unit  10  through an indoor air suction hole  111  (refer to  FIG. 3 ) formed in the front cover  11 . Preferably, the fan  15  may be a centrifugal fan that sucks air in its axial direction and discharges the air in its radial direction. The sucked air passes through the filter  13  such that impurities can be removed from the air. After the filter  13 , the air is guided to a top portion of the grill  14  by the shroud  145  where the air is further guided by an air guide  144  to a discharge grill  141  formed on a side of the grill  14 . Through the discharge grill  141 , the air is discharged back to an indoor area.  
      When a ventilation mode is selected, indoor air is sucked into the air cleaning unit  10  through an exhaust grill  148  formed on a side of the grill  14 , and then is directed toward an exhaust duct  32  (refer to  FIG. 7 ) connected with the air cleaning unit  10 . Meanwhile, outdoor air is sucked into the air cleaning unit  10  through a supply duct  31  (refer to  FIG. 7 ) connected with the air cleaning unit  10 . The sucked outdoor air passes through the filter  13  and is discharged from the air cleaning unit  10  to the indoor area through the discharge grill  141  of the grill  14 .  
       FIG. 4  is a perspective view showing a first embodiment of an installation case according to the present invention.  
      Referring to  FIG. 4 , an installation case  17  of the current embodiment is characterized in that the installation case  17  is coupled to the air cleaning unit  10  when the air cleaning unit  10  is connected to a supply duct and an exhaust duct that are formed through a wall. When assemble, the installation case  17  is coupled to one side of the rear panel  16 . In detail, one end of the rear panel  16  is bent downwardly (refer to  FIG. 2 ). The bent end of the rear panel  16  is inwardly recessed in correspondence with the installation case  17  for receiving the installation case  17 .  
      In detail, the installation case  17  includes bar receiving surfaces  171  on both top sides for receiving one ends of the installation bars  18 , a wiring penetration hole  174  formed in an edge portion, and a suction hole  173  and an exhaust hole  172  formed through a front portion. The rear panel  16  includes a suction hole and an exhaust hole in the bent end for communicating with the suction hole  173  and the exhaust hole  172  of the installation case  17 .  
       FIG. 5  is a perspective view showing a second embodiment of the installation case of the air cleaning unit  10  according to the present invention.  
      Referring to  FIG. 5 , an installation case  27  of the current embodiment is characterized in that the installation case  27  is coupled to the air cleaning unit  10  when the air cleaning unit  10  is connected to a supply duct and an exhaust duct that are formed through a ceiling.  
      In detail, the installation case  27  includes a suction hole  273  and an exhaust hole  272  that are formed from a front surface to a top surface, bar receiving surfaces  271  formed in both top sides for receiving the installation bars  18 , and bar inserting holes  271   a  formed in rear ends of the bar receiving surfaces  271  and having a predetermined width.  
      In more detail, the bent end of the installation bar  18  is inserted into the bar inserting hole  271   a . The suction hole  273  and the exhaust hole  272  of the installation case  27  are connected to the suction hole and the exhaust hole of the rear panel  16 , respectively.  
       FIG. 6  shows a first embodiment of installing the air cleaning unit  10  in a building according to the present invention.  
      Referring to  FIG. 33 , in this embodiment, a supply duct and an exhaust duct are formed in a wall of the building for connection with the air cleaning unit  10 .  
      In detail, a duct member  30  includes a supply duct  31  (refer to  FIG. 7 ) and an exhaust duct  32  (refer to  FIG. 7 ). The duct member  30  is formed in the wall of the building. In this case, the installation bar  17  of  FIG. 31  having the suction hole  173  and the exhaust hole  172  in a front-to-back direction is used for installing the air cleaning unit  10  in the building. In detail, the installation case  17  and the installation bars  18  are coupled to each other and then attached to a ceiling while aligning the suction hole  173  and the exhaust hole  172  with the supply duct  31  and the exhaust duct  32 . Next, fasteners are inserted into the ceiling through the coupling holes  184  of the installation bars  18  for securely fix the installation bars  18  and the installation case  17  to the ceiling. Then, the air cleaning unit  10  is pushed in the direction of arrow to coupling the installation bars  18  to the installation bar mounting structure of the rear panel. In this way, the air cleaning unit  10  can be mounted on the ceiling.  
       FIG. 7  is an exploded perspective view showing an air flow throughout the air cleaning unit  10  in ventilation mode.  
      Referring to  FIG. 7 , the suction hole  173  of the installation case  17  is connected to the supply duct  31 , and the exhaust hole  172  of the installation case  17  is connected to the exhaust duct  32 .  
      In detail, outdoor air is introduced into the air cleaning unit  10  from the supply duct  31  through the suction hole  163  of the rear panel  16 . Here, the indoor air suction hole  111  of the front cover  11  can be opened to perform both the ventilation mode and cleaning mode, or closed to perform only the ventilation mode. For this, the suction panel  112  may be openably mounted on the front cover  11  as described above.  
      In more detail, outdoor air introduced through the supply duct  31  flows along the filter housing  147  of the grill  14  down to a lower end of the filter housing  147  and reaches the bottom of the filter  13 . Then, the outdoor air passes through the filter  13  upwardly toward the fan  15 . Here, since the pressure around the bottom of the filter  13  is lower than the atmospheric pressure due to the operation of the fan  15 , the outdoor air introduced through the suction duct  31  flows down to the bottom of the filter  13 . That is, since air flows from a high pressure area to a low pressure area, the outdoor air flows along the filter housing  147  down to the bottom of the filter  13 .  
      Further, while passing through the filter  13  in an upward direction, the outdoor air are sequentially cleaned by the pre filter  131 , the HEPA filter  132 , and the deodorization filter  133 . After passing through the deodorization filter  133 , the outdoor air reaches fan  15  through the orifice  143 . Since the fan  15  is a centrifugal fan that sucks air in an axial direction and blows the air in a radial direction, the outdoor air is horizontally blown by the fan  15 . Then, the outdoor air is guided by a discharge guide  165  (refer to  FIG. 3 ) of the rear panel  16  and the air guide  144  of the grill toward the discharge grill  141 . Finally, the outdoor air is discharged to an indoor area through the discharge grill  141 .  
      While the outdoor air is introduced from the supply duct  31 , polluted indoor air is expelled through the exhaust door  32 .  
      In detail, a discharge fan can be installed in the exhaust duct  32  or on an end of the exhaust duct  32  to indoor air through the exhaust duct  32 . Further, a heat recovery ventilator can be installed between the exhaust duct  32  and the supply duct  31  for heat exchange.  
      In more detail, when the pressure inside the exhaust duct  32  decreases by the operation of the discharge fan connected to the exhaust duct  32 , indoor air is introduced into the exhaust duct  32  through the exhaust grill  148 . As explained above, the exhaust grill  148  is formed on a side portion and a bottom portion of the air cleaning unit  10  for rapidly discharge polluted indoor air to an outdoor area. The indoor air sucked through the exhaust grill  148  does not flow to the supply duct  31  owing to the compartment wall  138  and the air guide  144  (refer to  FIG. 2 ) of the grill  14 .  
       FIG. 8  is a bottom perspective view showing an air flow throughout the air cleaning unit  10  in cleaning mode.  
      Referring to  FIG. 8 , in cleaning mode, indoor air is sucked through the indoor air suction hole  111  and passes through the filter  13 . While passing through the filter  13 , the indoor air is cleaned. Then, the indoor air is discharged back to an indoor area through the discharge grill  141  of the grill  14 .  
      Meanwhile, when the cleaning mode is selected, the suction hole  163  connected to the supply duct  31  can be closed.  
      In detail, although the fan  15  rotates in the cleaning mode, the indoor air is not sucked through the exhaust grill  148 . Therefore, it is not required to screen the exhaust hole  162  using an additional part. However, since the suction hole  163  communicates with the filter  13 , outdoor air can be introduced into the air cleaning unit  10  through the suction hole  163  when the indoor air is sucked through the indoor air suction hole  111 .  
      Therefore, to perform only the cleaning mode by preventing outdoor air from flowing into the air cleaning unit  10  through the suction hole  163  connected to the supply duct  31  in the cleaning mode, an additional mechanism can be employed for selectively close the suction holes  163  and  173 . In one embodiment, an opening/closing unit can be installed on a front side or a back side of the suction hole  173  of the installation case  17 . A micro computer can be used to automatically operate the opening/closing unit according to a selected mode.  
      Alternatively, the opening/closing unit can be installed on a front side of a back side of the suction hole  163  of the rear panel  16 . For example, a plate having a size larger than or equal to that of the suction hole  163  or  173  can be rotatably or slidable installed to selectively open and close the suction hole  163  or  173 . Here, the opening/closing mechanism is not limited. Various opening/closing mechanisms can be used.  
      The air flow in the cleaning mode will now be more fully described. In cleaning mode, the fan  15  is operated to suck air from an indoor area through the indoor air suction hole  111 . The sucked indoor air is cleaned while passing through the filter  13 , and then reaches the fan  15 . The indoor air is blown by the fan  15  in a radial direction and guided by the air guide  144  and the discharge guide  165  to the discharge grill  141  where the indoor air is discharged back to the indoor area.  
      As described above, both in the cleaning mode and the ventilation mode, air introduced into the air cleaning unit  10  passes through the filter  13 . Therefore, clean air can be supplied to the indoor area. Further, the discharge grill  141  is formed in three directions of the air cleaning unit  10 , so that air discharged from the air cleaning unit  10  into the indoor area can be circulated throughout the indoor area. In other words, if the discharge grill  141  is formed in a downward direction of the air cleaning unit  10 , air discharged from the air cleaning unit  10  cannot be circulated throughout the indoor area. Furthermore, the exhaust grill  148  is formed on a side portion and a bottom portion of the air cleaning unit  10 , so that polluted indoor air can be rapidly expelled to the outdoor area. In addition, the indoor air suction hole  111  is formed in the bottom of the air cleaning unit  10 , and the discharge grill  141  is formed on the side portions of the air cleaning unit  10 , so that air discharged from the discharge grill  141  is not directly sucked through the indoor air suction hole  111 . Further, in cleaning mode, indoor air is sucked and discharged in multiple directions, so that the indoor air can be quickly cleaned. Furthermore, the air cleaning unit  10  can be operated in both ventilation and cleaning modes at the same time. On the contrarily, the air cleaning unit  10  can be operated either in ventilation mode or in cleaning mode by movably installing the suction panel  112 .  
       FIG. 9  shows a second embodiment of installing the air cleaning unit  10  in a building according to the present invention.  
      Referring to  FIG. 9 , the air cleaning unit  10  is connected to a duct member  30  formed in a ceiling.  
      In detail, the air cleaning unit  10  can be connected to the duct member  30  formed in the ceiling by using the installation case  27  of  FIG. 32 . The suction hole  273  of the installation case  27  is connected to a branch supply duct  311  formed on a bottom surface of a supply duct  31  of the duct member  30 . The exhaust hole  272  of the installation case  17  is connected to a branch exhaust duct  321  formed on a bottom surface of an exhaust duct  32  of the duct member  30 . Alternatively, the suction hole  273  and the exhaust hole  272  of the installation case  17  can be directly connected to one ends of the supply duct  31  and the exhaust duct  32 , respectively. In detail, when a plurality of air cleaning unites is connected to the duct member  30 , the air cleaning unites may be connected to the duct member  30  through branch ducts. On the contrary, when a single air cleaning unit is connected to the duct member  30 , the air cleaning unit may be directly connected to an end of the duct member  30 .  
       FIG. 10  is a system diagram showing the air cleaning unit  10  connected to a ventilation unit according to the present invention, and  FIG. 11  is a sectional view showing a schematic air flow of the system shown in  FIG. 10 .  
      Referring to  FIGS. 10 and 11 , the air cleaning unit  10  is connected to the heat recovery system  35  such as a ventilation unit through a duct member  30  such that the air cleaning unit  10  can provide both ventilation and air-cleaning.  
      In detail, one ends of a supply duct  31  and an exhaust duct  32  of the duct member  30  are connected to the air cleaning unit  10 , and the other ends are connected to the heat recovery ventilator  35 . In the heat recovery ventilator  35 , outdoor air to the air cleaning unit  10  exchanges heat with indoor air from the air cleaning unit  10 . Therefore, the temperature of an indoor area is not rapidly fluctuated by the outdoor air supplied to the indoor area. For example, when the indoor temperature is higher than the outdoor temperature, heat is transferred from the indoor air discharged from the air cleaning unit  10  to the outdoor air to decrease temperature difference between the indoor area and the outdoor air supplied to the indoor area, thereby preventing temperature fluctuation in the indoor area.  
      The other ends of the supply duct  31  and the exhaust duct  32  can be connected to a supply duct connecting tube  33  and an exhaust duct connecting tube  34 . The supply duct connecting tube  33  and the exhaust duct connecting tube  34  are connected to a heat recovery ventilator  40 .  
      The heat recovery ventilator  40  includes an exhaust inlet  42  formed on one side, a supply outlet  43  formed at a predetermined distance from the exhaust inlet  42 , an exhaust outlet  44  formed on the opposite side to the exhaust inlet  42 , a supply inlet  45  formed on the opposite side to the supply outlet  43 , and an heat exchanger  41 .  
      The heat recovery ventilator  40  further includes an exhaust fan  47  installed in a tube between the exhaust inlet  42  and the exhaust outlet  44 , and a supply fan  46  installed between a tube between the supply inlet  45  and the supply outlet  43 .  
      In detail, the exhaust inlet  42  and the supply outlet  43  are formed on the same side of the heat recovery ventilator  40 , and the exhaust outlet  44  and the supply inlet  45  are formed on the same side of the ventilator  40 . However, the positions of the exhaust inlet  42  and the supply outlet  43  or the exhaust outlet  44  and the supply inlet  45  can be changed according to the type of the heat recovery ventilator  40 .  
      In more detail, the exhaust inlet  42  is connected to the exhaust duct connecting tube  34  to allow inflow of indoor air from the air cleaning unit  10 , and the supply outlet  43  is connected to the supply duct connecting tube  33  to supply outdoor air to the air cleaning unit  10 .  
      When the exhaust fan  47  operates, indoor air is sucked into the heat recovery ventilator  40  through the exhaust inlet  42  and discharged from the heat recovery ventilator  40  to an outdoor area through the exhaust outlet  44 . Further, when the supply fan  46  operates, outdoor air is sucked into the heat recovery ventilator  40  through the supply inlet  45  and discharged through the supply outlet  43  to the air cleaning unit  10  where the outdoor air is supplied to an indoor area. Here, the indoor air sucked through the exhaust inlet  42  and the outdoor air sucked through the supply inlet  45  exchange heat with each other while passing through the heat exchanger  41 .  
      The outdoor air introduced into the air cleaning unit  10  through the supply outlet  43  is cleaned while passing through the filter  13  and then supplied to the indoor area through the discharge grill  141  of the grill  14 . The indoor air is introduced into the heat recovery ventilator  40  from the indoor area through the exhaust grill  148  of the air cleaning unit  10 , the exhaust duct  32 , and the exhaust inlet  42 , and then discharged to the outside area through the exhaust outlet  44 .  
      In this configuration of the air conditioning system, the heat recovery ventilator  40  and the air cleaning unit  10  operate together when a ventilation mode is selected.  
      In detail, when the ventilation mode is selected, the fan  15  of the air cleaning unit  10 , the supply and exhaust fans  46  and  47  of the heat recovery ventilator  40  are operated. The supply fan  46  draws outdoor air into the hear recovery ventilator  40  and blows the outdoor air to the air cleaning unit  10  through the supply duct  31 . The fan  15  of the air cleaning unit  10  forces the introduced outdoor air through the filter  13 . The outdoor air cleaned by the filter  13  is discharged to the indoor area through the discharge grill  141 . The exhaust fan  47  sucks air from the indoor air through the exhaust grill  148  formed on one side of the air cleaning unit  10 . Then, the indoor air is introduced into the heat recovery ventilator  40  through the exhaust duct  32 . In the heat recovery ventilator  40 , the outdoor air and the indoor air change heat with each other while passing through the heat exchanger  41 .  
       FIG. 12  is an exploded perspective view of the duct member  30  according to the present invention.  
      Referring to  FIG. 30 , the duct member  30  of the present invention includes the supply duct  31  for allowing inflow of outdoor and the exhaust duct  32  for outflow of indoor air.  
      In detail, the duct member  30  includes straight tubes  312  and  322  having a predetermined length, elbows  313  and  323  having a predetermined curvature, an equally-shaped connector  301  connecting one straight tubes  312  and  322  to another straight tubes  312  and  322  or to the elbows  313  and  323 , and differently-shaped connectors  314  and  324  connecting the straight tubes  312  and  322  or the elbows  313  and  323  to the heat recovery ventilator  40 . The duct member  30  is fixed to a ceiling using a hanger  302 .  
      When the air cleaning unit  10  is not located in line with the heat recovery ventilator  40 , the elbows  313  and  323  are used to change the direction of the duct member  30 . The differently-shaped connectors  314  and  324  has one ends corresponding to the straight tubes  312  and  322  or the elbows  13  and  323 , and the other ends corresponding to the supply outlet  34  and the exhaust inlet  42 .  
      The elbows  313  and  323  and the connector  301  are sized such that the straight tubes  312  and  322  can be inserted into the elbows  313  and  323  or the connector  301  by a predetermined length. Therefore, leakage of air at joints of the duct member  30  can be prevented.  
      FIGS.  13  to  15  show air conditioning systems according to embodiments of the present invention.  
      Referring to  FIG. 13 , an air cleaning unit  10  is connected to a heat recovery ventilator  40  through a duct member  30 . The air cleaning unit  10  and the heat recovery ventilator  40  can be installed in the same indoor compartment or different indoor compartments. For example, the heat recovery ventilator  40  can be mounted on an outermost wall of a building for directly sucking outdoor air into the heat recovery ventilator  40 , and the air cleaning unit  10  can be mounted on an inner wall of the building in connection with the heat recovery ventilator  40  via the duct member  30 . The duct member  30  is disposed using proper numbers of straight tubes and elbows according to the location of the air cleaning unit  10  and heat recovery ventilator  40 .  
      In case where the duct member  30  is connected between the heat recovery ventilator  40  and the air cleaning unit  10  through an inner wall of the building, the installation case  17  showing in  FIG. 4  can be installed on one side of the air cleaning unit  10  for facilitating the connection between the air cleaning unit  10  and the duct member  30 .  
      The distance between a wall and one side of the air cleaning unit  10  where a discharge grill  141  is formed can be changed according to the position of one end of the duct member  30  connected to the air cleaning unit  10 .  
      Referring to  FIG. 14 , at least two air cleaning units  10  can be connected to a single heat recovery ventilator  40  depending on the configuration of a duct member  30 .  
      In detail, the duct member  30  includes a supply duct  31  and an exhaust duct  32 . The supply duct  31  and the exhaust duct  32  include straight tubes and elbows. One air cleaning unit  10  is connected to one ends of the supply duct  31  and the exhaust duct  32 . A branch supply duct  311  branches off from the supply duct  31  in an upward or downward direction, and a branch exhaust duct  321  branches off from the exhaust duct  32  in an upward or downward direction. Another air cleaning unit  10  is connected to one ends of the branch supply duct  311  and the branch exhaust duct  321 . The air cleaning units  10  may be installed in different indoor area compartments.  
      Referring to  FIG. 15 , air cleaning units  10  are connected to a duct member  30  in different methods depending on the structure of the duct member  30  formed in an indoor area.  
      In detail, when the duct member  30  passes through a ceiling of one indoor area compartment and a wall of another indoor area compartment, the air cleaning units  10  can be connected to the duct member  30  using different installation cases.  
      In more detail, when the duct member  30  passes through a ceiling, and a branch supply duct and an branch exhaust duct extend downward from the duct member  30 , an air cleaning unit  10  provided with an installation case  27  as shown in  FIG. 5  can be installed in an indoor area compartment in connection with the branch supply duct and the branch exhaust duct. Further, when the duct member  30  further extends to another indoor area compartment through a wall, another air cleaning unit  10  provided with an installation case  17  as shown in  FIG. 4  can be installed on the wall of the another indoor area compartment in connection with leading ends of a supply duct  31  and an exhaust duct  32  of the duct member  30 .  
      As shown in  FIG. 15 , one air cleaning unit  10  is connected to one duct member  30  using the ceiling installation method, and another air cleaning unit  10  is connected to the same duct member  30  using the wall installation method. Further, as shown in  FIG. 14 , air cleaning units  10  can be installed in the respective indoor area compartments by connecting additional branch duct members between the duct member  30  and the air cleaning units  10 .  
       FIG. 16  shows a block diagram of an air conditioning system according to another embodiment of the present invention.  
      Referring to  FIG. 16 , a plurality of air cleaning units  10  is connected to one heat recovery ventilator  40 . For this, a distributing unit  50  can be installed on one ends of a supply duct  31  and an exhaust duct  32  that extend from the heat recovery ventilator  40 .  
      In detail, a plurality of duct members branch off from the distributing unit  50 , and the air cleaning units  10  are connected to ends of the duct members. Therefore, since a plurality of air cleaning units  10  can be connected to the heat recovery ventilator  40  using the distributing unit  50  and duct members disposed between the distributing unit  50  and the respective air cleaning units  10 , branch ducts extending from a duct member are not required.  
       FIG. 17  shows a block diagram of an air conditioning system according to another embodiment of the present invention;  
      Referring to  FIG. 17 , the air conditioning system of the current embodiment includes a heat recovery ventilator  40 , an air cleaning unit  10 , and an additional device such as a humidifier  60  between the heat recovery ventilator  40  and the air cleaning unit  10 .  
      In detail, the humidifier  60  is installed in a duct member connected between the heat recovery ventilator  40  and the air cleaning unit  10  in order to supply air having a proper humidity to an indoor area.  
      In more detail, the humidifier  60  is installed in a supply duct  31  of the duct member connected between the heat recovery ventilator  40  and the air cleaning unit  10 , such that outdoor air can be introduced into the air cleaning unit  10  at a desired humidity. Particularly, the humidifier  60  may be installed in the middle of the supply duct  31  to increase air humidity passing through the supply duct in dry spring. Therefore, outdoor air can be supplied at a predetermined humidity and thus an additional humidifier is not required for each indoor area compartment.  
      Further, a heater or an air cooling unit can be installed in place of or in conjunction with the humidifier  60  for heating outdoor air to the indoor area in winter or cooling outdoor air to the indoor area in summer. Therefore, energy loss can be reduced during circulation of indoor air and outdoor air.  
       FIGS. 18 and 19  are system diagrams of air conditioning systems according to another embodiments of the present invention.  
      Referring to  FIG. 18 , an air cleaning unit  10  is connected to a heat recovery ventilator  40  through a duct member  30 . The air cleaning unit  10  and the heat recovery ventilator  40  can be installed in the same indoor are compartment or different indoor area compartments.  
      A supply duct connecting tube  33  connected to a supply outlet of the heat recovery ventilator  40  branches into two, and one of the branches is connected to a supply duct  31  and the other is connected to a diffuser  70 . Therefore, outdoor air supplied through the supply outlet of the heat recovery ventilator  40  can be discharged to one indoor area compartment through the supply duct  31  and the air cleaning unit  10  and to another indoor area compartment through the diffuser  70 . Since an end of the diffuser  70  and the air cleaning unit  10  are disposed in different indoor area compartments, the environments of the indoor are compartments can be differently controlled.  
      When the duct member  30  is connected between the heat recovery ventilator  40  and the air cleaning unit  10  through wall, an installation case having suction and exhaust holes in a front-to-back direction can be installed on one side of the air cleaning unit  10  for connection between the duct member  30  and the air cleaning unit  10 .  
      The distance between a wall and a discharge grill formed on one side of the air cleaning unit  10  may be varied according to the location of one end of the duct member  30  passing through a wall.  
      Referring to  FIG. 19 , an air conditioning system of the current embodiment is characterized in that a distributing unit  50  is installed on an end of a diffuser  70  and a plurality of discharge tubes  72  branches off from the distributing unit  50 .  
      In detail, when a duct member  30  connected to a heat recovery ventilator  40 - passes through a ceiling of one indoor area compartment and a wall of another indoor area compartment, air cleaning units  10  can be connected to the duct member  30  using different installation cases as described above. The diffuser  70  can be directly connected to a supply duct connecting tube as shown in  FIG. 18  or branch off from a supply duct  31  as shown in  FIG. 19 . The distributing unit  50  is installed on an end of the diffuser  70 , and a plurality of discharge tubes  72  branches off from the distributing unit  50  toward a plurality of indoor area compartments.  
       FIGS. 20 and 21  are system diagrams of air conditioning systems according to another embodiments of the present invention.  
      Referring to  FIG. 20 , an air cleaning unit  10  is connected to a ventilation unit such as a heat recovery ventilator  40  through a duct member  30 . The air cleaning unit  10  and the heat recovery ventilator  40  can be installed in the same indoor area compartment or different indoor area compartments.  
      A branch supply duct  311  can branch off from one side of a supply duct  31  of the duct member  30 , and an air cooling unit  80  can be connected to one end of the branch supply duct  311 . The branch supply duct  311  provides the same function as the diffuser  70  shown in  FIG. 19 .  
      In detail, the branch supply duct  311  can be connected to an indoor unit or an outdoor unit of the air cooling unit  80 . In more detail, when the branch supply duct  311  is connected to the indoor unit of the air cooling unit  80 , outdoor air is cooled in the heat recovery ventilator  40  and then supplied to the indoor unit of the air cooling unit  80 . In the indoor unit of the air cooling unit  80 , the outdoor air is further cooled by an indoor heat exchanger (i.e., an evaporator) and then discharged to an indoor area.  
      Though not shown in  FIG. 20 , when the branch supply duct  311  is connected to the outdoor unit of the air cooling unit  80 , the outdoor unit can operate at a higher efficiency than in the related art.  
      In detail, outdoor air introduced into the heat recovery ventilator  40  exchanges heat with indoor air discharged from an indoor area through an exhaust duct connecting tube  34 , such that the outdoor air can be cooled. Then, the outdoor air flows through a supply duct connecting tube  33 , the supply duct  31 , and the branch supply duct  311  toward the outdoor unit of the air cooling unit  80  where the outdoor air exchanges heat with refrigerant.  
      In a related art outdoor unit of an air cooling unit, outdoor air is directly introduced into the outdoor unit and exchanges heat with refrigerant flowing through a heat exchanger. However, in the present invention, outdoor air is cooled by the heat recovery ventilator  40  and then supplied to the outdoor unit of the air cooling unit  80 . Therefore, the heat exchanging efficiency of the outdoor unit can be improved.  
      Instead of the air cooling unit  80 , a heat pumping unit or air conditioning unit with a heating function can be connected to the end of the branch supply duct  311 . In detail, the heat pumping unit includes an outdoor unit and an indoor unit, and the branch supply duct  311  is connected to the outdoor unit or the indoor unit of the heat pumping unit. Outdoor air is supplied through the branch supply duct  311  into the outdoor unit or the indoor unit of the heat pumping unit where the outdoor air changes heat with refrigerant flowing inside a heat exchanger. In more detail, when the branch supply duct  311  is connected to the outdoor unit of the heat pumping unit, outdoor air is supplied from the branch supply duct  311  to the outdoor unit of the heat pumping unit at a temperature higher than an outdoor temperature since the outdoor air is supplied to the outdoor unit after being heated in the heat recovery ventilator  40  by heat exchange with discharging indoor air. Therefore, refrigerant flowing inside the heat exchanger of the outdoor unit can take much heat from the introduced outdoor air so that the heat exchanging efficiency of the outdoor unit of the heat pumping unit can be improved. In the following embodiments of the present invention, a heat pumping unit can be installed instead of an air cooling unit  80  as described in the current embodiment. Thus, description thereof will be omitted.  
      Referring to  FIG. 21 , a plurality of air cooling units  80  can be connected to a branch supply duct  311 , and a plurality of air cleaning units  10  can be connected to a supply duct  31  and an exhaust duct  32  of a duct member  30 . Each of the air cooling units  80  or the air cleaning units  10  can be independently installed in each indoor area compartment. The air cleaning units  10  can be connected to the duct member  30  by a ceiling or wall installation method. The installation method of the air cleaning unit  10  can be easily determined from the structure of the duct member  30  and an installation case attached to the air cleaning unit  10 .  
      Although the branch supply duct  311  is connected to an indoor unit of each air cooling unit  80  in  FIG. 21 , the branch supply duct  311  can be connected to an outdoor unit of the air cooling unit  80  as described above.  
       FIG. 22  is a block diagram of an air conditioning system according to another embodiment of the present invention.  
      Referring to  FIG. 22 , the air conditioning system of the current embodiment is characterized in that an air cooling unit  80  is connected between a heat recovery ventilator  40  and an air cleaning unit  10 . Air discharged from the air cooling unit  80  is entirely or partially supplied to the air cleaning unit  10  through a supply duct  31 .  
      In detail, the supply duct  31  extends from the heat recovery ventilator  40  to the air cooling unit  80  and further extends from the air cooling unit  80  to the air cleaning unit  10 . An exhaust duct  32  extends from the air cleaning unit  10  directly to the heat recovery ventilator  40 . Therefore, the air conditioning system can provide air-cooling as well as ventilation and air-cleaning.  
      Air cooled by the air cooling unit  80  is supplied to the air cleaning unit  10  where the air passes through a filter and thus impurities such as dust are removed from the air. In other words, indoor or outdoor air is cleaned by a filter installed in the air cooling unit  80  and further cleaned by the filter installed in the air cleaning unit  10 , so that very clean air can be supplied to an indoor area.  
      In detail, when the supply duct  31  is connected to an outdoor unit of the air cooling unit  80 , indoor air may be introduced into an indoor unit of the air cooling unit  80  and all or some of the indoor air discharged from the indoor unit may be introduced into the air cleaning unit  10 . When the supply duct  31  is connected to the indoor unit of the air cooling unit  80 , outdoor air may be supplied to the indoor unit and discharged from the indoor unit in a cooled state. All or some of the cooled outdoor air may be supplied to the air cleaning unit  10 . Further, in ventilation mode, indoor air introduced into the air cleaning unit  10  is directed to the heat recovery ventilator  40 , where the indoor air exchanges heat with outdoor air introduced into the heat recovery ventilator  40  from an outdoor area and then discharged to the outdoor area.  
       FIG. 23  is a block diagram of an air conditioning system according to another embodiment of the present invention.  
      Referring to  FIG. 23 , the air conditioning system of the current embodiment includes a heat recovery ventilator  40 , an air cooling unit  80 , a distributing unit  50 , and a plurality of air cleaning units  10  connected to the distributing unit  50 .  
      In detail, the heat recovery ventilator  40  is connected to an outdoor unit or an indoor unit of the air cooling unit  80  through a supply duct  31 , and the air cooling unit  80  is connected to the distributing unit  50  to supply cooled air to the distributing unit  50 . The distributing unit  50  distributes the air to the plurality of air cleaning units  10 . Then, the air is discharged to indoor areas through discharge grills of the air cleaning units  10 . Here, the air cleaning units  10  are installed in respective indoor area compartments divided by walls.  
      In ventilation mode, indoor air is sucked into the air cleaning units  10  and then sent to the distributing unit  50  through exhaust ducts  32 . The indoor air collected in the distributing unit  50  is sent to the heat recovery ventilator  40  through an exhaust duct  32  directly connected between the distributing unit  50  and the heat recovery ventilator  40 . Then, the indoor air is discharged to an outdoor area from the heat recovery ventilator  40 .  
       FIG. 24  is a block diagram of an air conditioning system according to another embodiment of the present invention.  
      Referring to  FIG. 24 , the air conditioning system of the current embodiment includes a heat recovery ventilator  40 , a distributing unit  50  connected to the heat recovery ventilator  40 , and a plurality of air cooling units  80  and an air cleaning unit  10  that are connected to the distributing unit  50 .  
      In detail, the heat recovery ventilator  40  and the distributing unit  50  are connected through a supply duct  31 . A plurality of branch tubes  51  extends from the distributing unit  50 . The plurality of air cooling units  80  and the air cleaning unit  10  are connected to one ends of the branch tubes  51 . An exhaust duct  32  extends from the air cleaning unit  10  to the heat recovery ventilator  40 .  
      In this configuration, outdoor air drawn by the heat recovery ventilator  40  is directed along the supply duct  31  to the distributing unit  50  where the outdoor air is supplied to the air cooling units  80  and the air cleaning unit  10  through the branch tubes  51 . In ventilation mode, indoor air is drawn into the air cleaning unit  10  and sent to the heat recovery ventilator  40  through the exhaust duct  32 . Then, the indoor air is discharged to an outdoor area from the heat recovery ventilator  
      As described above, the air conditioning system of the present invention provides clean air to a number of indoor air compartments using a single ventilation unit.  
      Further, the air cleaning unit operates in conjunction with the hear recovery ventilator such that temperature difference can be reduced between inflow of outdoor air and outflow of indoor air, thereby minimizing indoor area cooling or heating loss.  
      Furthermore, since a plurality of air cleaning units can be connected to a single heat recovery ventilator by varying the shape and arrangement of the duct member, air can be supplied to each indoor area compartment using the single heat recovery ventilator through the air cleaning units.  
      In addition, a heat or a humidifier can be installed between the heat recovery ventilator and the air cleaning unit, such that humidity controlling and air heating functions can be provided in addition to the ventilation and air cleaning functions.  
      According to the air conditioning system of the present invention, a plurality of air cleaning units can be connected to a single heat recovery ventilator by varying the shape and arrangement of duct member connecting the air cleaning units and the heat recovery ventilator. Therefore, the present invention can be applied to various fields.  
      It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.