Patent Publication Number: US-2015059413-A1

Title: Laundry treatment apparatus

Description:
Pursuant to 35 U.S.C. §119(a), this application claims the benefit of Korean Patent Application No. 10-2013-0105541, filed on Sep. 3, 2013, Korean Patent Application No. 10-2013-0105543, filed on Sep. 3, 2013, and Korean Patent Application No. 10-2013-0105720, filed on Sep. 3, 2013, each of which is hereby incorporated by reference as if fully set forth herein. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to laundry treatment apparatuses. 
     2. Discussion of the Related Art 
     Laundry treatment apparatuses are electronic apparatuses that may implement washing and/or drying of a washing object (laundry). Examples of laundry treatment apparatuses include a washing machine, a drying machine, and a combined washing and drying machine. 
     Laundry treatment apparatuses that may function to dry laundry may be classified into laundry treatment apparatuses having an exhaust drying system and laundry treatment apparatuses having a circulation drying system according to how heated air (hot air) supplied to laundry after heat exchange between the air and the laundry is treated. 
     A circulation drying system is a system that condenses air discharged from a receiving space in which laundry is stored and thereafter heats the condensed air (i.e., heating after dehumidification) to resupply the air to the receiving space. An exhaust drying system is a system that continuously supplies hot air into the receiving space and discharges air subjected to heat exchange from the laundry treatment apparatus. 
     In the case of laundry treatment apparatuses having a circulation drying system, provision of a cooling water supply structure may be essential because it is necessary to dehumidify air discharged from the receiving space using cooling water prior to resupplying the air to the receiving space. Therefore, laundry treatment apparatuses having a circulation drying system may consume an excessive quantity of cooling water when cooling efficiency is low. 
     On the other hand, laundry treatment apparatuses having an exhaust drying system may cause excessive energy consumption because they discharge air exchanged heat with laundry despite the fact that the air has a higher temperature than that of outside air. 
     SUMMARY 
     The present disclosure is directed to a laundry treatment apparatus 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 a laundry treatment apparatus, a control method thereof, with an advanced concept drying system which may reduce the consumption of energy and cooling water required to dry laundry. 
     Another object of the present invention is to provide a laundry treatment apparatus, and a control method thereof, with a drying system which may achieve enhanced drying efficiency. 
     A further object of the present invention is to provide a laundry treatment apparatus, and a control method thereof, with a cooling water supply structure which may prevent cooling water from reaching laundry to be dried. 
     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 purposes of the invention, as embodied and broadly described herein, a laundry treatment apparatus includes a tub providing a space to store wash water, a drum within the tub, the drum storing laundry therein, a circulation duct to guide air discharged from the tub back to the tub, a fan located in the circulation duct to circulate air from the tub, a heater located in the circulation duct to heat the air, an exhaust duct to discharge some of the air introduced into the tub from the tub, a suction duct to introduce air from outside of the tub into the tub, and a water supply unit to supply water into the tub so as to cool the tub. 
     The laundry treatment apparatus may further include a controller to control opening/closing of the water supply unit, and the controller may control the water supply unit to supply water into the tub during operation of the fan and the heater. 
     The controller may rotate the drum at a first Revolutions Per Minute (RPM) and a second RPM during operation of the fan and the heater, the first RPM may be set to a value at which the centrifugal force of laundry caused by rotation of the drum becomes greater than the weight of the laundry, and the second RPM may be set to a value greater than the first RPM. 
     The controller may control the water supply unit to supply water into the tub while the drum is rotated at the second RPM. 
     The water supply unit may supply water into the tub through the circumference of the tub at a position spaced apart from a vertical line passing a rotation center of the drum by a predetermined distance in a width direction of the tub. 
     The suction duct and the exhaust duct may remain in an open state during operation of the heater and the fan. 
     The suction duct may be located in a flow path through which interior air of the tub is directed to the fan such that outside air of the tub is introduced into the circulation duct through the suction duct. 
     The cross sectional area of the exhaust duct may be less than the cross sectional area of the circulation duct. 
     The quantity of air discharged through the exhaust duct and the quantity of air introduced through the suction duct may be set to be equal to each other. 
     The quantity of air discharged through the exhaust duct may be set to be greater than the quantity of air introduced through the suction duct. 
     The laundry treatment apparatus may further include a drain unit configured to discharge water stored in the tub from the tub, and the exhaust duct may be connected to the drain unit. 
     A junction of the exhaust duct and the drain unit may be located higher than the set maximum water level of the tub. 
     The laundry treatment apparatus may further include a switchover valve configured to open or close the exhaust duct. 
     The laundry treatment apparatus may further include a flow path valve configured to prevent air introduced into the drain unit through the exhaust duct from being supplied into the tub. 
     In accordance with another aspect of the present invention, a laundry treatment apparatus includes a drum in which laundry is stored, a heater to heat air, a first heat exchange flow path including a tub to provide a space in which the drum is received and a space in which air is condensed and a duct through which some of interior air of the tub is directed to the heater and then resupplied to the tub, a second heat exchange flow path including a duct through which outside air of the tub is guided into the tub by way of the heater and a duct through which some of interior air of the tub is discharged from the tub, and a water supply unit to supply water into the tub so as to cool the tub. 
     The laundry treatment apparatus may further include a controller to control opening/closing of the water supply unit and RPM of the drum, and the controller may supply water into the tub while the drum is rotated at predetermined reference RPM or more. 
     The laundry treatment apparatus may further include a water supply guide configured to introduce water supplied from the water supply unit into the tub, and the water supply guide may be positioned to allow water introduced into the tub to move to the bottom of the tub along an inner circumferential surface of the tub. 
     The water supply guide may be located at the circumference of the tub at a position spaced apart from a vertical line passing through a rotation center of the drum by a predetermined distance in a width direction of the tub. 
     The water supply guide may be located between a vertical line tangent to the circumference of the drum and a vertical a tangent to the circumference of the tub. 
     The tub may further include a water supply communication portion (fourth communication portion) perforated in the circumference of the tub to communicate with the water supply unit, and the water supply guide may include a trap body accommodated in the water supply communication portion to provide a space in which water is stored, an outer circumferential surface of the trap body being spaced apart from an inner circumferential surface of the water supply communication portion by a predetermined distance, and a guide pipe fixed to the water supply communication portion to guide water into the trap body, the guide pipe defining a flow path for communication between a space between the outer circumferential surface of the trap body and the inner circumferential surface of the water supply communication portion and the interior of the trap body. 
     The bottom of the trap body may be spaced apart from an outlet of the guide pipe by a predetermined distance, and the space between the outer circumferential surface of the trap body and the inner circumferential surface of the water supply communication portion may have an open plane for communication between the interior of the trap body and the interior of the tub. 
     The open plane may take the form of a semicircle or arc located farther from a vertical line passing a rotation center of the drum on the basis of a line passing a center of the water supply communication portion to extend parallel to the longitudinal direction of the tub. 
     The suction duct may include a suction port through which outside air is introduced, the suction port being fixed to the circulation duct, and a discharge port through which the air introduced through the suction port is supplied into the tub, the discharge port being fixed to the tub. 
     The circulation duct may be fixed to the top of an outer circumferential surface of the tub. 
     The laundry treatment apparatus may further include a duct communication portion (first communication portion) configured to discharge interior air of the tub into the circulation duct, and the discharge port may be located in the duct communication portion. 
     The circulation duct may further include a fixing portion to which the suction port is connected. 
     The circulation duct may further include a first filter provided at the fixing portion to filter air to be introduced into the suction port. 
     The laundry treatment apparatus may further include a second filter located in the duct communication portion (first communication portion) to filter air to be directed from the tub to the circulation duct. 
     The laundry treatment apparatus may further include a filter washer to supply wash water to the second filter so as to wash the second filter. 
     The suction duct may include a coupling section located below the circulation duct to communicate with the tub, the coupling section being provided with the discharge port, and an extension section extending from the coupling section to the circulation duct, the extension section being provided with the suction port. 
     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: 
         FIGS. 1   a ,  1   b , and  2  show a laundry treatment apparatus according to the present invention; 
         FIGS. 3   a  and  3   b  show a suction duct included in the laundry treatment apparatus according to the present invention; 
         FIG. 4  shows a flow path switchover unit included in the laundry treatment apparatus according to the present invention; 
         FIGS. 5   a  and  5   b  show a water supply unit and a water supply guide included in the laundry treatment apparatus according to the present invention; 
         FIG. 6  shows another embodiment of the laundry treatment apparatus according to the present invention; 
         FIG. 7  shows a control process of the laundry treatment apparatus according to the present invention; and 
         FIGS. 8   a - 8   c  and  9   a - 9   d  respectively show first motion and second motion. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Meanwhile, a configuration of an apparatus that will be described hereinafter and a control method of the apparatus are provided for explanation of the exemplarily embodiments of the present invention and are not intended to limit the technical scope of the present invention. The same reference numerals of the entire specification designate the same constituent elements. 
     As exemplarily shown in  FIGS. 1   a ,  1   b , and  2 , a laundry treatment apparatus of the present invention, designated by reference numeral  100 , includes a cabinet  1  defining an external appearance of the apparatus  100 , laundry receptacles  2  and  3  placed within cabinet  1  and configured to store a washing object (laundry) and wash water therein, a circulation duct  7  through which interior air of laundry receptacles  2  and  3  is circulated, an exhaust duct  83  through which some of the interior air of laundry receptacles  2  and  3  is discharged from laundry receptacles  2  and  3 , a suction duct  81  through which outside air is supplied into laundry receptacles  2  and  3  and a heating unit configured to supply heated air into laundry receptacles  2  and  3 . 
     Cabinet  1  includes a front panel  11  defining a front surface of laundry treatment apparatus  100 . Front panel  11  is provided with an opening  13  through which laundry is introduced into or removed from the laundry receptacles  2  and  3 . 
     Opening  13  is opened or closed by a door ( 14  see  FIG. 6 ) rotatably coupled to cabinet  1 . 
     In addition, a control panel  17  may be mounted to front panel  11 . Control panel  17  serves as a user interface to enable information exchange between a user and a controller (not shown) of laundry treatment apparatus  100 . 
     More specifically, control panel  17  includes a power input part  179  which assists the user in inputting a power supply instruction to laundry treatment apparatus  100  and an input part  175  which assists the user in selecting a laundry treatment method that laundry treatment apparatus  100  can provide. 
     The “laundry treatment method” selected via input part  175  is a set of time-variant control instructions or time-invariant control instructions required to allow the controller (not shown) to control respective devices included in laundry treatment apparatus  100  so as to supply moisture or air to laundry. 
     The “laundry treatment method” as described above is typically called a laundry treatment course, a control method of a laundry treatment apparatus, or the like. A plurality of laundry treatment methods may be programmed in the laundry treatment apparatus  100 . 
     In addition, control panel  17  may further include a display part  177  which displays information regarding the laundry treatment method selected by the user or an operation procedure of laundry treatment apparatus  100 . 
     The “information regarding the operation procedure of the laundry treatment apparatus” displayed on display part  177  includes the name of a laundry treatment method selected by the user via input part  175 , a set time for the selected laundry treatment method, a completion target time or remaining time of a laundry treatment method that is being executed, requirements that laundry treatment apparatus  100  requests the user for execution of the laundry treatment method selected by the user, and the like (i.e., information related to operation of laundry treatment apparatus  100 ). 
     The laundry receptacles accommodated in cabinet  1  may include a tub  2  in which wash water is stored and a drum  3  in which laundry is stored, drum  3  being rotatably accommodated in tub  2 . 
     Tub  2  has a cylindrical shape and is fixed in cabinet  1  via tub support members  21 . Tub  2  has a tub opening  22  formed in a front surface thereof to communicate with opening  13 . 
     A gasket  23  is interposed between tub opening  22  and opening  13 . Gasket  23  may serve not only to prevent vibration generated by tub  2  from being transmitted to cabinet  1 , but also to prevent leakage of wash water stored in tub  2 . To this end, gasket  23  may be formed of an elastic material, such as rubber. 
     Drum  3  is rotatably supported in tub  2  via a drive unit M (see  FIG. 6 ) that is mounted to a rear surface of tub  2 . Drum  3  has a drum opening  31  communicating with tub opening  22  and through-holes  33  perforated in the circumference of drum  3 . 
     Circulation duct  7  serves as a flow path through which interior air of tub  2  is discharged from tub  2  and then is again guided into tub  2 . Circulation duct  7  may be installed on the top of an outer circumferential surface of tub  2 . 
     To couple with circulation duct  7 , tub  2  may have a first communication portion  26  and a second communication portion  27 . 
     As exemplarily shown in  FIG. 2 , first communication portion  26 , (i.e., duct communication portion) serves as a flow path through which interior air of tub  2  is guided to circulation duct  7 , and second communication portion  27  serves as a flow path through which air introduced into circulation duct  7  is guided to tub  2 . 
     Second communication portion  27  may be formed in gasket  23 . That is, second communication portion  27  takes the form of an aperture formed in gasket  23  and an air outlet of circulation duct  7  may be fitted into the aperture formed in gasket  23 . 
     Although both first communication portion  26  and second communication portion  27  may be formed in the circumference of tub  2 , positioning second communication portion  27  at gasket  23  may guide air discharged from circulation duct  7  to the center of drum  3  through drum opening  31 , which may advantageously increase heat exchange efficiency between the laundry and the air. 
     The heating unit, provided to supply heated air into tub  2 , may include a fan  71  and a heater  73  which are accommodated in circulation duct  7 . Fan  71  serves not only to move interior air of tub  2  into circulation duct  7  through first communication portion  26 , but also to move the air introduced into circulation duct  7  to second communication portion  27 . Heater  73  serves to heat the air moved to second communication portion  27  by fan  71 . 
     In this case, first communication portion  26  and second communication portion  27  may be located in a diagonal direction on the basis of a cross section of tub  2  parallel to the ground on which cabinet  1  is supported. Heater  73  may be located such that a portion of heater  73  extends in a longitudinal direction of circulation duct  7 . Increase in the length of the flow path defined by circulation duct  7  serves to achieve sufficient time required to heat air moving through circulation duct  7 . 
     In laundry treatment apparatus  100  of the present invention, some of the air to be supplied to heater  73  is introduced through suction duct  81  and some of the hot air supplied into tub  2  is discharged from tub  2  through exhaust duct  83 . 
     Suction duct  81  may be located in a flow path along which interior air of tub  2  is guided to fan  71 . This serves to allow interior air of tub  2  as well as outside air of tub  2  to be introduced into and circulated through circulation duct  7  by fan  71  installed in circulation duct  7  without providing suction duct  81  with an additional air introduction device. 
       FIG. 2  shows a case in which suction duct  81  causes outside air of tub  2  to be introduced into circulation duct  7  through first communication portion  26 , by way of example. In this case, negative pressure is applied to first communication portion  26  upon rotation of fan  71 , causing interior air of tub  2  as well as air outside of tub  2  to be introduced into circulation duct  7 . 
     Meanwhile, as exemplarily shown in  FIGS. 3   a  and  3   b , suction duct  81  according to the present invention does not require a control device (e.g., a valve) to control opening/closing of suction duct  81 . That is, suction duct  81  according to the present invention may be continuously kept open. 
     Suction duct  81  may be comprised of a coupling section  811  communicating with first communication portion  26  and an extension section  813  extending from coupling section  811  to circulation duct  7 . In this case, extension section  813  may be provided with a suction port  815  for introduction of outside air and coupling section  811  may be provided with a discharge port  817  for connection between suction duct  81  and first communication portion  26 . 
     Extension section  813  may extend from coupling section  811  in a vertical direction of the tub  2  by a predetermined length. This serves to prevent bubbles generated by detergent during washing of laundry from being discharged from tub  2  through suction duct  81 . 
     Suction duct  81  according to the present invention has one end fixed to tub  2  and the other end fixed to circulation duct  7 . This configuration is achieved as circulation duct  7  according to the present invention is fixed at the top of the outer circumferential surface of tub  2 . 
     Considering laundry treatment apparatus  100  of the present invention in terms of a vibration system, circulation duct  7  and tub  2  will exhibit almost the same vibration, and, therefore, the vibrations have no effect on the durability of suction duct  81  installed to interconnect tub  2  and circulation duct  7 . 
     Assuming a configuration in which circulation duct  7  is fixed to cabinet  1  rather than being fixed at the top of the outer circumferential surface of tub  2 , circulation duct  7  will vibrate independent of vibration of tub  2 , which makes it difficult to maintain durability of suction duct  81  without an additional vibration absorbing device. 
     To fix a free end of suction duct  81  (i.e., the end of suction duct  81  provided with the suction port  815 ), circulation duct  7  may further include a fixing portion  75  to which suction port  815  is connected. 
     Fixing portion  75  may have any one of various shapes so long as the free end of suction duct  81  can be fixed thereto.  FIG. 3  shows a case in which fixing portion  75  takes the form of a board connecting circulation duct  7  and suction port  815  to each other by way of example. 
     Additionally, suction duct  81  may further include a first filter F1 which filters air to be introduced into extension section  813 . In consideration of the fact that outside air of tub  2  is supplied into tub  2  through suction duct  81 , provision of filter F1 as described above serves to prevent laundry received in tub  2  from being contaminated by impurities contained in the outside air and to prevent malfunction of heating unit  71 / 73  due to the impurities. 
     In this case, first filter F1 may be installed in a hole perforated in fixing portion  75  and suction port  815  may be fixed to fixing portion  75  to surround first filter F1. 
     Meanwhile, a second filter F2 may be installed in first communication portion  26  to filter interior air of tub  2  to be introduced into circulation duct  7 . 
     First filter F1 is kept exposed outside of circulation duct  7 , thus being easily washable. On the other hand, second filter F2 is not exposed outside of circulation duct  7  and, thus, washing of second filter F2 is difficult. For this reason, according to the present invention, a filter washer F3 to wash second filter F2 may be additionally provided. 
     Filter washer F3 may be installed at any position in first communication portion  26  so long as wash water can be ejected towards second filter F2 to remove impurities remaining on second filter F2. In  FIG. 3(   b ) shows a case in which filter washer F3 is located between second filter F2 and fan  71  by way of example. 
     To avoid interference with filter washer F3, coupling section  811  may extend in a width direction of the 2 by a predetermined length and thereafter be joined with extension section  813 . 
     Exhaust duct  83  may be installed at any position of tub  2  so long as it can discharge some of air introduced into tub  2  through circulation duct  7  to the outside of tub  2 . 
       FIG. 1  shows a case in which exhaust duct  83  is installed to a third communication portion  28  formed at an upper position of the circumference of tub  2 . When air is suctioned into tub  2  by fan  71 , the interior of tub  2  becomes a positive pressure state, causing some of the interior air of tub  2  to be discharged to the outside of tub  2  having atmospheric pressure (i.e., lower pressure than the interior of tub  2 ) through exhaust duct  83  and the remaining interior air of tub  2  to move into circulation duct  7  through first communication portion  26  having negative pressure. 
     To allow only some of the air supplied into tub  2  through circulation duct  7  to be discharged through exhaust duct  83 , the cross sectional area of exhaust duct  83  may be less than the cross sectional area of first communication portion  26  (or the cross sectional area of circulation duct  7 ). 
     Meanwhile, to maintain a constant flow rate of air into tub  2 , the flow rate of air that can be discharged from exhaust duct  83  (exhaustion capacity) may be equal or similar to the flow rate of air that can be suctioned into suction duct  81  (suction capacity). 
     Although exhaust duct  83  may be configured to communicate the interior of tub  2  with the outside of cabinet  1  so as to guide air introduced through exhaust duct  83  to the outside of cabinet  1 , exhaust duct  83  may be connected to a drain unit  6  that serves to discharge wash water from tub  2 . 
     When exhaust duct  83  is in direct communication with the outside of cabinet  1 , air discharged from exhaust duct  83  may be condensed on an indoor wall because the air discharged through exhaust duct  83  is humid air. 
     Laundry treatment apparatus  100  of the present invention may solve the problem described above by connecting exhaust duct  83  to drain unit  6  that is included to discharge wash water in tub  2  to the outside of cabinet  1 . 
     In this case, a flow path switchover unit  9  may be installed at a junction of exhaust duct  83  and drain unit  6  to control opening/closing of exhaust duct  83  and drain unit  6 . This serves to prevent air discharged through exhaust duct  83  from entering tub  2  and to prevent water discharged through drain unit  6  from entering tub  2 . 
     Drain unit  6  according to the present invention may include a first drain flow path  61  and a pump  63  which serve to discharge wash water from tub  2 , a second drain flow path  65  through which the wash water having passed through pump  63  is guided to flow path switchover unit  9  and a third drain flow path  67  through which water directed to flow path switchover unit  9  is guided to an outdoor location (not shown), such as a drain. 
     Flow path switchover unit  9  installed at the junction of exhaust duct  83  and drain unit  6  may be located higher than the set maximum water level H (see  FIG. 6 ) of tub  2 . 
     Conventional laundry treatment apparatuses generally include a structure (hereinafter referred to as water trap) to prevent water in a flow path connected to the outdoor location (i.e., the aforementioned third drain flow path) from being completely discharged, in order to prevent bad smell from entering the laundry treatment apparatus through the third drain flow path. 
     In a case in which exhaust duct  83  according to the present invention is connected to the drain unit provided with the water trap, interior air of tub  2  cannot be discharged from tub  2  through exhaust duct  83  during drying of laundry. Therefore, under connection of exhaust duct  83  to the drain unit of conventional laundry treatment apparatuses, a controller needs to control revolutions per minute of the fan to blow air at pressure sufficient for removal of the water trap. 
     However, in a case in which flow path switchover unit  9  is located higher than the set maximum water level of tub  2  according to the present invention, exhaust duct  83  serves as an anti-siphon member to create a water trap between flow path switchover unit  9  and pump  63  (in the second drain flow path  65 ), thereby preventing bad smell from entering tub  2 . 
     Air introduced into exhaust duct  83  may be discharged from tub  2  through flow path switchover unit  9  and third drain flow path  67 , and therefore it is unnecessary to control revolutions per minute of fan  71  for removal of the water trap. 
     Additionally, through the configuration as described above, even if wash water is supplied to the set maximum water level of tub  2 , it is possible to prevent wash water from being unintentionally discharged from tub  2  through drain unit  6 . 
     Flow path switchover unit  9  according to the present invention may have a shape as exemplarily shown in  FIG. 4 . 
     Flow path switchover unit  9  may include a switchover unit body  91  located at a junction of exhaust duct  83  and second drain flow path  65 , a duct connection pipe  93  connecting exhaust duct  83  and switchover unit body  91  to each other, a flow path connection pipe  95  connecting second drain flow path  65  and switchover unit body  91  to each other, and a discharge pipe  97  connecting third drain flow path  67  and switchover unit body  91  to each other. 
     Duct connection pipe  93  and flow path connection pipe  95  may be arranged to face each other. Duct connection pipe  93  may be located at the top of switchover unit body  91  and flow path connection pipe  95  may be located at the bottom of switchover unit body  91 . 
     In this case, a switchover valve  99  to open or close duct connection pipe  93  is received in switchover unit body  91 . Switchover valve  99  includes a valve body  991  configured to open or close duct connection pipe  93  and a valve rotating shaft  993  configured to rotatably couple valve body  991  to switchover unit body  91 . 
     Valve body  991  keeps duct connection pipe  93  open by the weight thereof, but duct connection pipe  93  is closed by water pressure when wash water is introduced into switchover unit body  91  through second drain flow path  65 . 
     Meanwhile, flow path switchover unit  9  having the configuration as described above may prevent wash water discharged from tub  2  from entering tub  2  through duct connection pipe  93 , but may not eliminate the possibility of air discharged from tub  2  being resupplied to tub  2  through flow path connection pipe  95 . 
     As described above, owing to the water trap created in second drain flow path  65 , the present invention may prevent air discharged through exhaust duct  83  from entering tub  2 . However, the water trap may not be created in second drain flow path  65  when no discharge of wash water ever happens before drying of laundry. 
     Accordingly, flow path switchover unit  9  according to the present invention may further include a flow path valve  951  to open or close flow path connection pipe  95 . Flow path valve  951  may include a check valve which opens flow path connection pipe  95  only when wash water is introduced into switchover unit body  91  through second drain flow path  65 . 
     As exemplarily shown in  FIGS. 1 and 2 , laundry treatment apparatus  100  of the present invention may further include a water supply unit  4  which supplies wash water into tub  2  and a detergent supply unit  5  which supplies detergent into tub  2 . 
     Water supply unit  4  may include a water supply flow path  43  which connects tub  2  and the water supply source (not shown) at the outside of laundry treatment apparatus  100  to each other and a water supply valve  41  which opens or closes water supply flow path  43  under control of the controller (not shown). 
     Meanwhile, detergent supply unit  5  may include a detergent reservoir  53  in which detergent is stored and a tub supply pipe  55  which connects detergent reservoir  53  and tub  2  to each other. Water supply flow path  43  may have any shape so long as it can supply water to detergent reservoir  53 . In this case, detergent stored in detergent reservoir  53  and water required for laundry washing may be supplied into tub  2  as soon as the controller (not shown) opens water supply valve  41 . 
     Meanwhile, detergent reservoir  53  may be withdrawn from front panel  11 . To this end, detergent supply unit  5  may include a body  51  configured to support detergent reservoir  53  such that detergent reservoir  53  may be withdrawn from front panel  11 . Front panel  11  has a reservoir opening  15  through which detergent reservoir  53  is withdrawn. 
     In this case, the interior of detergent reservoir  53  must communicate with body  51  and tub supply pipe  55  must be configured to enable communication between body  51  and the interior of tub  2 . 
     The controller (not shown) may control water supply unit  4  to allow water supply unit  4  to supply water required to cool tub  2  (required to condense interior air of tub  2 ) into tub  2  (for enhancement of drying efficiency). 
     In consideration of the fact that humid interior air of tub  2  may be condensed in detergent supply unit  5  and supplying water into tub  2  during drying of laundry may unintentionally cause laundry stored in drum  3  to be wet, the laundry treatment apparatus  100  of the present invention may further include a water supply guide  25  for communication between tub supply pipe  55  and tub  2 . 
     Water supply guide  25  according to the present invention has a feature of defining a water trap (of continuously storing a constant amount of water to prevent communication between tub  2  and detergent supply unit  5 ), so as to prevent interior air of tub  2  from entering detergent supply unit  5  and to cause water supplied into tub  2  via water supply unit  4  to move to the bottom of tub  2  along an inner circumferential surface of tub  2  so as not to reach laundry stored in drum  3 . 
     As exemplarily shown in  FIG. 5 , water supply guide  25  may be formed in a fourth communication portion  29  (i.e., a water supply communication portion) located at an upper position of the circumference of tub  2 . 
     Fourth communication portion  29 , as exemplarily shown in the drawing, may take the form of a pipe protruding from the circumference of tub  2 , or may take the form of an aperture perforated in the circumference of tub  2 . 
     Water supply guide  25  includes a trap body  251  which is accommodated in fourth communication portion  29  to provide a water storage space, shims  253  which serve to maintain a constant gap between an outer circumferential surface of trap body  251  and an inner circumferential surface of the fourth communication portion  29  and a guide pipe  255  which is fixed to the fourth communication portion  29  to guide water supplied through tub supply pipe  55  into trap body  251 . 
     Guide pipe  255  may include a guide pipe body  255   a  configured to guide water into trap body  251  and a flange  255   b  formed at the circumference of guide pipe body  255   a  to fix guide pipe body  255   a  to the fourth communication portion  29 . 
     A diameter of guide pipe body  255   a  is determined such that an outer circumferential surface of guide pipe body  255   a  is spaced apart from an inner circumferential surface of trap body  251  by a predetermined distance. A length of guide pipe body  255   a  is determined such that the bottom of guide pipe body  255   a , from which water is discharged, is spaced apart from the bottom of trap body  251  by a predetermined distance. 
     Flange  255   b  must be configured to clog a space between the outer circumferential surface of guide pipe body  255   a  and the inner circumferential surface of the fourth communication portion  29 . As exemplarily shown in  FIG. 5 , flange  255   b  may be supported by an upper surface of the fourth communication portion  29 . 
     Accordingly, water supplied into detergent reservoir  53  through water supply flow path  43  is supplied into trap body  251  through tub supply pipe  55  and guide pipe body  255   a  and, in turn, the water supplied into trap body  251  is introduced into tub  2  through a space between the inner circumferential surface of trap body  251  and the outer circumferential surface of guide pipe body  255   a  and a space between the outer circumferential surface of trap body  251  and the inner circumferential surface of the fourth communication portion  29 . 
     A constant amount of water is always stored in trap body  251  and the bottom of guide pipe body  255   a  (not provided with flange  255   b ) is continuously immersed in the water stored in trap body  251 , which prevents humid air within tub  2  from being supplied into detergent supply unit  5 . 
     Additionally, water supply guide  25  as described above is located in the fourth communication portion  29  at a position spaced apart from a vertical line X passing a rotation center C1 of drum  3  in a width direction Y of tub  2  by a predetermined distance. As such, water supply guide  25  may function to prevent water supplied into tub  2  during drying from reaching laundry stored in drum  3 . 
     Moreover, the effects as described above may be maximized by positioning the fourth communication portion  29  such that water supply guide  25  is located between a vertical line X1 tangent to the circumference of drum  3  and a vertical line X2 tangent to the circumference of tub  2  in a height direction of tub  2 . 
     Meanwhile, in a case in which positioning water supply guide  25  at the above-described position is difficult, a flow path defined in water supply guide  25  may be positioned at the above-described position to achieve the effects as described above. 
     As exemplarily shown in  FIG. 5(   b ), the plural shims  253  may be arranged on the outer circumferential surface of trap body  251  to fix trap body  251  to the fourth communication portion  29 . Space between the respective two neighboring shims  253  serve as flow paths through which water inside trap body  251  is introduced into tub  2 . 
     Accordingly, when some of the spaces between the respective neighboring shims  253  have closed planes  259  and the other spaces have open planes  257  and each open plane  257  is located between vertical line X1 and vertical line X2, it is possible to prevent water supplied into tub  2  during drying from reaching laundry. 
     That is, open plane  257  may take the form of a semicircle or arc located farther away from the vertical line X passing the rotation center C1 of drum  3  on the basis of a line Z that passes a center C2 of the fourth communication portion  29  and is parallel to the longitudinal direction of tub  2 . 
     When open plane  257  has an arc shape, the length of open plane  257  may be a quarter of the perimeter of trap body  251  or more and less than the perimeter of trap body  251 . When viewed in terms of angle, the center of the arc-shaped open plane  257  may be 45 degrees or more and less than 180 degrees on the basis of the center C2 of the fourth communication portion  29 . 
     The shape and positional features of open plane  257  as described above are given to prevent water supplied during drying from reaching laundry and to minimize increase of a water supply time during washing. 
     Hereinafter, a drying system (a process of drying laundry by supplying heated air to the laundry) realized by laundry treatment apparatus  100  of the present invention as described above will be described with reference to  FIG. 2 . 
     When fan  71  is operated, interior air of tub  2  is introduced into circulation duct  7  through first communication portion  26  and, in turn, the air introduced into circulation duct  7  is heated by the heater  73  and thereafter supplied into tub  2  through second communication portion  27 . The air supplied into tub  2  undergoes heat exchange with laundry stored in drum  3  and thereafter moves to the first communication portion  26 . 
     The surface of tub  2  is kept at a lower temperature than at the center of tub  2  because of heat exchange between tub  2  and interior air of cabinet  1  (or air introduced into cabinet  1  through a cabinet opening  19 , for example). Accordingly, as air discharged from drum  3  is cooled while moving to the first communication portion  26 , some moisture contained in the air is condensed at the inner circumferential surface of tub  2 . 
     That is, tub  2 , circulation duct  7 , fan  71 , and heater  73  according to the present invention constitute a circulation drying system (including a first heat exchange flow path and the heating unit) that implements dehumidification of air discharged from tub  2 , heating of the dehumidified air and resupply of the heated air to tub  2 . 
     Meanwhile, some of the air exchanged heat with the laundry is discharged from tub  2  through exhaust duct  83  and the remaining air is collected into circulation duct  7  through the first communication portion  26 . In this process, the air is mixed with outside air introduced into tub  2  through suction duct  81 . 
     Although the air discharged from drum  3  is dehumidified via heat exchange with tub  2  while moving to the first communication portion  26 , the air collected in circulation duct  7  may not remain in a sufficiently dehumidified state according to the quantity of laundry (i.e., the quantity of laundry stored in drum  3 ). Exhaust duct  83  and suction duct  81  serve to solve this problem. 
     That is, according to the present invention, some air introduced into the first communication portion  26  is discharged from cabinet  1  through exhaust duct  83 , which may reduce the quantity of humid air to be introduced into circulation duct  7 . In addition, dry air (outside air of tub  2 ) supplied through suction duct  81  is mixed with air moved from tub  2  to circulation duct  7 , which may reduce the humidity of air to be directed to heater  73  to a desired level. 
     Suction duct  81 , fan  71 , heater  73 , and exhaust duct  83  according to the present invention constitute an exhaust drying system (including a second heat exchange flow path and the heating unit) that serves not only to heat outside air of tub  2  so as to supply the heated air into tub  2 , but also to discharge some of air exchanged heat with laundry from tub  2 . 
     Accordingly, owing to a combined drying system of the circulation drying system and the exhaust drying system, the present invention may prevent deterioration of drying efficiency regardless of the quantity of laundry or the kind of laundry (regardless of the humidity of air discharged from tub  2 ). 
     To achieve the effects as described above, exhaust duct  83  and suction duct  81  may always remain in an open state during drying and the quantity of air introduced into circulation duct  7  through suction duct  81  (suction capacity) and the quantity of air discharged from tub  2  through exhaust duct  83  (exhaust capacity) may be equal to each other. 
     Meanwhile, the exhaust capacity may be set to be greater than the suction capacity when coincidence of the suction capacity and the exhaust capacity is difficult, although coincidence of the suction capacity and the exhaust capacity provides maximum drying efficiency. 
     When the suction capacity is greater than the exhaust capacity, the quantity of hot air supplied into tub  2  increases and, in turn, an increase in the quantity of hot air supplied into tub  2  means increase in the quantity of air to be dehumidified in tub  2 . Thus, when suction duct  81  and exhaust duct  83  are configured such that the suction capacity is greater than the exhaust capacity, drying laundry without using cooling water may cause deterioration of drying efficiency. Accordingly, the exhaust capacity may be set to be greater than the suction capacity. 
     Although the drying system as described above has a risk of increasing drying time according to the quantity of laundry, the present invention has solved this problem via control of water supply unit  4 . That is, the drying system according to the present invention may solve the above-described risk as the controller (not shown) controls water supply unit  4  so as to supply water to the inner circumferential surface of tub  2  during drying of laundry. 
     Supplying water via water supply unit  4  to the inner circumferential surface of tub  2  during drying causes rapid cooling of the inner circumferential surface of tub  2 , which may allow air introduced into circulation duct  7  to remain at a low humidity (in other words, may allow air introduced into circulation duct  7  to remain at high dryness). 
     The water supplied into tub  2  via water supply unit  4  moves to drain unit  6  along the inner circumferential surface of tub  2  under guidance of water supply guide  25  and, therefore, there is substantially less risk of the water reaching laundry stored in drum  3  thus causing increased drying time. 
     Meanwhile, to conserve water, supplying water into tub  2  via water supply unit  4  is implemented according to user selection. To this end, control panel  17  may further include a first mode selection part  171  for drying of laundry via supply of water into tub  2  and a second mode selection part  173  for drying of laundry without supply of water into tub  2  (see  FIG. 1(   b )). 
     Meanwhile, laundry treatment apparatus  100  of the present invention as described above may have a configuration as exemplarily shown in  FIG. 6 . 
     Laundry treatment apparatus  100  as exemplarily shown in  FIG. 6  has substantially the same configuration as the laundry treatment apparatus as exemplarily shown in  FIGS. 1 to 5  except for a connection relationship between circulation duct  7 , suction duct  81 , and exhaust duct  83 . 
     More specifically, according to the embodiment show in  FIG. 6 , tub  2  receives outside air (interior air of cabinet  1  or outside air of cabinet  1 ) through suction duct  81 , interior air of tub  2  is discharged from exhaust duct  83 , and some of the interior air of tub  2  is guided to suction duct  81  through circulation duct  7  (connection duct). 
     Fan  71  and heater  73  are accommodated in suction duct  81 , and circulation duct  7  is connected to a flow path of suction duct  81  through which air is guided to fan  71  (i.e., the circulation duct is connected between fan  71  and an inlet of suction duct  81 ). 
     In the present embodiment, similarly, the circulation drying system is defined by a first heat exchange flow path and heating unit  71 / 73 . The first heat exchange flow path is constructed by tub  2 , circulation duct  7  (connection duct), and a partial flow path of suction duct  81  through which air having passed through fan  71  is guided into tub  2 . 
     Meanwhile, in the present embodiment, the exhaust drying system is defined by a second heat exchange flow path and heating unit  71 / 73 , and the second heat exchange flow path is constructed by suction duct  81 , tub  2 , and exhaust duct  83 . 
     Accordingly, the present embodiment may also have the same effects as those of the above embodiment described with reference to  FIGS. 1 to 5 . 
       FIG. 7  shows a control method of laundry treatment apparatus  100  as described above. The control method of laundry treatment apparatus  100  according to the present invention may include drying operation S 30  for supplying heated air into tub  2  and motion execution operation S 50  for rotating drum  3  based on predetermined motion during implementation of drying operation S 30 . 
     Drying operation S 30  includes a circulation process S 31  for discharging interior air of tub  2  from tub  2  and thereafter resupplying the air to tub  2 , an exhaust process S 33  for discharging some of the air supplied into tub  2  from tub  2 , a suction process S 35  for mixing circulated air via circulation process S 31  with outside air of tub  2  and a heating process S 37  for heating the air to be supplied into the tub  2 . 
     Circulation process S 31  is a process in which interior air of tub  2  moves through circulation duct  7  via operation of fan  71 . Circulation process S 31  is initiated simultaneously with operation of fan  71 . During circulation process S 31 , only some of the interior air of tub  2  is introduced into circulation duct  7 . That is, some of the interior air of tub  2  is resupplied to tub  2  via the circulation process S 31  and some of the interior air of tub  2  is discharged from tub  2  via exhaust process S 33 . 
     Exhaust process S 33  is implemented using exhaust duct  83  and, therefore, air discharged from tub  2  via exhaust process S 33  moves to the outside of laundry treatment apparatus  100  through flow path switching unit  9  and third drain flow path  67 . 
     Suction process S 35  is implemented using suction duct  81  and suction duct  81  is installed to first communication portion  26  that connects circulation duct  7  and tub  2  to each other. Therefore, it will be appreciated that suction process S 35  is initiated when circulation process S 31  is initiated by operation of fan  71 . 
     Heating process S 37  is a process of heating mixed air in circulation duct  7  using heater  73 , the mixed air being acquired via circulation process S 31  and suction process S 35 . 
     Through the drying operation S 30  as described above, the present invention may implement supply of heated air, dehumidification of air exchanged heat with laundry, re-heating of some of air discharged from the tub, exhaust of some of air discharged from the tub, and supply of reheated air to laundry. 
     Motion execution operation S 50  is implemented during drying operation S 30 . Motion execution operation S 50  may be implemented to execute any one of first motion and second motion, or a first motion execution process S 53  and a second motion execution process S 51  may be implemented in a preset sequence. 
     The first motion execution process S 53  is a process of rotating drum  3  based on first motion. The first motion is motion in which drum  3  is rotated in any one direction among a clockwise direction and a counterclockwise direction to cause laundry to repeatedly come into close contact with and be separated from the inner circumferential surface of drum  3  (without tumbling), thereby achieving enhanced heat exchange efficiency between the laundry and hot air supplied into tub  2 . 
     The first motion execution process S 53  may include a process of rotating drum  3  at first Revolutions Per Minute (RPM) (reference RPM) (S 531 ), the first RPM being RPM at which the centrifugal force of laundry caused via rotation of drum  3  becomes greater than the weight of laundry, a process of rotating drum  3  at second RPM (S 533 ), the second RPM being set to be greater than the first RPM, and a process of repeating the two processes S 531  and S 533  a predetermined number of times or for a predetermined time period. 
     In the process of rotating drum  3  at the first RPM S 531  and in the process of rotating drum  3  at the second RPM S 533 , drum  3  is rotated in the same direction and the first RPM and the second RPM are RPMs that cause laundry to be rotated along with drum  3 . Therefore, during the first motion execution process S 53 , laundry will exhibit movement as exemplarily shown in  FIG. 8 . 
     That is, when drum  3  is rotated at the first RPM, laundry L remains in close contact with the inner circumferential surface of drum  3  for a given time (see  FIG. 8(   b )). When drum  3  is rotated at the second RPM, laundry L remains in close contact with the inner circumferential surface of drum  3  for a given time, but is in closer contact with the inner circumferential surface of drum  3  than when drum  3  is rotated at the first RPM ( ) see  FIG. 8(   a )). 
     This is because the second RPM is greater than the first RPM and, therefore, the centrifugal force of laundry L caused when drum  3  is rotated at the second RPM is greater than the centrifugal force of laundry L caused when drum  3  is rotated at the first RPM. 
     The reason for setting the first RPM and the second RPM to values that cause the laundry L to come into close contact with the inner circumferential surface of drum  3  so as to be rotated along with drum  3  is to attain a space for movement of hot air within drum  3 . Through this first motion, the surface area of laundry L that may come into contact with hot air supplied into tub  2  is maximized, which may increase heat exchange efficiency between the laundry L and the hot air supplied into tub  2 . 
     Meanwhile, the reason for setting the first RPM and the second RPM to different values is to allow through-holes  33  of drum  3  to be opened and closed by the laundry L. That is, this serves to confine hot air in drum  3  while drum  3  is rotated at the second RPM and to discharge interior air of drum  3  into tub  2  while drum  3  is rotated at the first RPM. 
     In the case of conventional laundry treatment apparatuses, some hot air introduced into drum  3  is discharged to tub  2  after undergoing heat exchange with the laundry, but some of the air introduced into drum  3  is directly discharged to tub  2  through through-holes  33  of drum  3  without heat exchange with laundry. Therefore, the conventional laundry treatment apparatuses suffer from increased energy consumption due to low heat exchange efficiency between hot air and laundry. 
     The present invention may solve the above problem of the conventional laundry treatment apparatuses by controlling the RPM of drum  3 . 
     A larger quantity of laundry will be distributed to cover the entire inner circumferential surface of drum  3  and come into close contact with the inner circumferential surface of drum  3  by high centrifugal force when drum  3  is rotated at the second RPM. Therefore, rotating drum  3  at the second RPM may minimize discharge of hot air from drum  3  to tub  2  through through-holes  33 . 
     Additionally, when drum  3  is rotated at the first RPM, laundry will remain in close contact with the inner circumferential surface of drum  3  by relatively low centrifugal force and, therefore, hot air may be discharged from drum  3  to tub  2  through through-holes  33 . 
     Time, which is set for the process of rotating drum  3  at the second RPM S 533  to further enhance heat exchange efficiency between laundry and hot air, may be longer than time set for the process of rotating drum  3  at the first RPM S 531 . 
     Since condensation efficiency of air moving to circulation duct  7  may vary according to a discharge time of hot air from drum  3  to tub  2  (i.e., the quantity of hot air discharged to tub  2 ), time for rotation of drum  3  at the first RPM and time for rotation of drum  3  at the second RPM are set to a given ratio.  FIG. 8  shows a case in which a ratio of the time for rotation of drum  3  at the first RPM to the time for rotation of drum  3  at the second RPM is 1:3 by way of example. 
     Meanwhile, the second motion execution process S 51  is a process of rotating drum  3  based on second motion. The second motion is motion in which rotation and rotation stop of drum  3  are repeated to cause laundry L to fall from above a horizontal line Y passing the rotation center C1 of drum  3  (i.e., motion to facilitate agitation of laundry and to increase heat exchange efficiency). 
     As exemplarily shown in  FIG. 7 , the second motion execution process S 51  may include a process of rotating drum  3  at third RPM (S 511 ), a process of stopping rotation of drum  3  before drum  3  completes 1 revolution (S 513 ), and a process of repeating the two processes S 511  and S 513  a predetermined number of times or for a predetermined time (S 515 ). 
     The third RPM is RPM at which the centrifugal force of laundry caused via rotation of drum  3  becomes greater than the weight of laundry. The third RPM may be equal to any one of the first RPM or the second RPM. 
     The process of stopping rotation of drum  3 , S 513 , is initiated when laundry is raised above half the height, h, of drum  3 . Thus, during implementation of the second motion execution process S 51 , laundry will exhibit movement as exemplarily shown in  FIG. 9 . 
     That is, when drum  3  is rotated at the third RPM (S 511 ), laundry L is rotated along with drum  3  while coming into close contact with the inner circumferential surface of drum  3  ((I) see  FIG. 9(   a )). Upon rotation stop of drum  3  when laundry L is raised above half the height, h, of drum  3 , the laundry L falls from above the horizontal line Y to the inner circumferential surface of drum  3  below the horizontal line Y ( ) see  FIG. 9(   b )). 
     Through this second motion, the surface area of laundry L exposed to hot air supplied into drum  3  is increased and moisture contained in laundry L is easily separated when laundry L collides with the inner circumferential surface of drum  3 . In this way, the present invention may achieve increased heat exchange efficiency between hot air and laundry (increased drying efficiency). 
     Additionally, the second motion prevents laundry L from becoming entangled in drum  3  because laundry L is repeatedly raised and dropped in drum  3 . 
     To maximize the effects as described above, the process of stopping rotation of drum  3  S 513  may be implemented by applying torque to drum  3  in a direction opposite to a rotating direction of drum  3  (i.e., a rotating direction of drum  3  at a point in time when the process of stopping rotation of drum  3  S 513  is initiated). This serves to provide laundry L with greater shock force. 
     The process of stopping rotation of drum  3  S 513  may be implemented when laundry L is rotated by an angle of 90 degrees or more and less than 180 degrees relative the lowermost point B of the rotation track of drum  3 . 
     The second motion as described above may be set to allow drum  3  to be rotated in any one direction among a clockwise direction and a counterclockwise direction as exemplarily shown in  FIG. 9(   c ), and may be set to allow drum  3  to alternately implement clockwise rotation and counterclockwise rotation as exemplarily shown in  FIG. 9(   d ). 
     The process of rotating drum  3  at the third RPM S 511  and the process of stopping rotation of drum  3  S 513  are repeated a predetermined number of times or for a predetermined time. The third RPM may be gradually increased whenever the second motion is repeated. 
     That is, assuming that the second motion is implemented plural times, RPM for initial execution of second motion may be less than RPM for subsequent execution of second motion (see  FIG. 9(   d )). 
     In addition, the third RPM set for the process of rotating drum  3  S 511  may be increased whenever the second motion is repeated and then reduced after the second motion is repeated a predetermined number of times. 
     Gradually increasing the third RPM whenever the second motion is repeatedly executed may ensure easy removal of moisture contained in laundry. 
     Meanwhile, the second motion execution process S 51  as described above may be implemented before the first motion execution process S 53 . This serves to prevent laundry from becoming entangled in drum  3  via the second motion, thereby allowing the laundry to be uniformly distributed at the inner circumferential surface of drum  3  during execution of the first motion. 
     In addition, time set for the first motion execution process S 53  may be longer than time set for the second motion execution process S 51 . This serves to increase time during which hot air supplied into drum  3  remains in drum  3 , thereby increasing heat exchange efficiency between laundry and hot air. 
     Although the control method of the present invention may include only the drying operation S 30  and the motion execution operation S 50  as described above, the control method may further include cooling water supply operation S 70  as exemplarily shown in  FIG. 7 . The cooling water supply operation S 70  is implemented to supply water to the inner circumferential surface of tub  2  during the motion execution operation S 50 , thereby cooling the inner circumferential surface of tub  2  exchanged heat with air discharged from drum  3 . 
     The cooling water supply operation S 70  according to the present invention may be implemented according to user selection. To this end, the control method of the present invention may further include mode selection operation S 10  for setting whether or not to implement the cooling water supply operation S 70  prior to initiating the drying operation S 30 . 
     In the mode selection operation S 10 , the user may input a control instruction using the first mode selection part  171  and the second mode selection part  173  provided at control panel  17 . 
     The first mode selection part  171  is used to select a control method (so-called ‘turbo drying mode’) for executing the cooling water supply operation S 70  during the motion execution operation S 50 , and the second mode selection part  173  is used to select a control method (so-called ‘blow drying mode’) for implementing the motion execution operation S 50  without the cooling water supply operation S 70 . 
     Meanwhile, in the mode selection operation S 10 , the controller (not shown) selects a first mode including the cooling water supply operation S 70  according to the quantity of laundry stored in drum  3  without input of a user instruction. 
     In any case, the control method of the present invention includes judging whether or not the first mode is selected upon initiation of the drying operation S 30  (S 40 ). 
     When the first mode is not selected (when the second mode is selected), the control method of the present invention executes only the second motion execution process S 51  and the first motion execution process S 53  in sequence. However, when the first mode is selected, the control method of the present invention executes the cooling water supply operation S 70  during the first motion execution process S 53 . 
     Heat exchange efficiency between laundry and hot air is low at the initial stage of the drying operation S 30 . Dryness of laundry has substantially no variation until the laundry reaches a given temperature and is rapidly increased from a point in time when the laundry reaches the given temperature. 
     This is because moisture contained in laundry is not evaporated until the laundry reaches a given temperature. Such rapid increase in the dryness of laundry means that the humidity of air discharged from drum  3  is increased as the drying operation S 30  is implemented. 
     Accordingly, in terms of drying of laundry, cooling tub  2  during the first motion execution process S 53 , which is initiated when a given time has passed after initiation of the drying operation S 30  (i.e., initiated when the second motion execution process S 51  ends), is more advantageous than cooling tub  2  during the second motion execution process S 51  which is initiated upon initiation of the drying operation S 30 . 
     Moreover, the cooling water supply operation S 70  may be implemented during the process of rotating drum  3  at the second RPM S 533  which is included in the first motion execution process S 51 . 
     Thereby, even if water supplied into tub  2  through water supply unit  4  unintentionally moves to drum  3 , it is possible to prevent the water from reaching laundry in drum  3  (this is because high RPM of drum  3  causes water colliding with the outer circumferential surface of drum  3  to move away from drum  3 ). 
     Thereafter, the control method of the present invention includes judging whether or not time taken for the drying operation S 30  and the motion execution operation S 50  exceeds drying time set in drying time setting operation S 20  (S 80 ), and ends the drying operation S 30  and the motion execution operation S 50  based on the judged result. 
     The drying time setting operation S 20  may be implemented prior to initiation of the drying operation S 30 . In the drying time setting operation S 20 , the controller (not shown) may set drying time based on the quantity of laundry, or the user may input the drying time using control panel  17 . 
     As is apparent from the above description, the present invention has the effect of providing a laundry treatment apparatus having an advanced concept drying system which may reduce consumption of energy and cooling water required to dry laundry, and a control method thereof. 
     In addition, the present invention has the effect of providing a laundry treatment apparatus having a drying system which may achieve enhanced drying efficiency, and a control method thereof. 
     In addition, the present invention has the effect of providing a laundry treatment apparatus having a cooling water supply structure which may prevent cooling water from reaching laundry to be dried, and a control method thereof. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the 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.