Patent Publication Number: US-8522578-B2

Title: Steam generator , and laundry device and method thereof

Description:
This application claims priority to International application No. PCT/KR2006/001025 filed on Mar. 21, 2006, Korean Application No. 10-2005-0025039 filed on Mar. 25, 2005 and Korean Application No. 10-2005-0025040 filed on Mar. 25, 2005, all of which are incorporated by reference, as if fully set forth herein. 
     TECHNICAL FIELD 
     The present invention relates to a laundry machine, and more particularly, to a new type laundry machine that is capable of more rapidly and efficiently washing or drying laundry and, furthermore, accomplishing the wrinkle removal and sterilization of the laundry. 
     BACKGROUND ART 
     Generally, laundry machines include a washing machine and a drying machine. The washing machine is a machine that is capable of removing contaminants from laundry using detergent and washing water. The drying machine is a machine that is capable of drying laundry to be dried, i.e., washed laundry, using hot air. 
     A drum type washing machine is a kind of washing machine which has been widely used in recent years. The drum type washing machine performs a washing operation using friction between a drum, which is rotated by a driving force of a motor, and laundry put in the drum under the condition that detergent and washing water are also put in the drum. The drum type washing machine has various effects in that damage to the laundry is minimized, the laundry is not entangled, and the laundry is struck and ribbed. 
     Also, there is a drum type washing-and-drying machine that is capable of performing a washing operation of laundry in the same manner as the drum type washing machine and, furthermore, even drying the washed laundry. 
     The drum type washing-and-drying machine supplies air into the drum through a drying duct having a drying heater and a blowing fan to perform a drying operation of the laundry. 
     However, the conventional drum type washing machine or the conventional drum type washing-and-drying machine has the following problems. 
     First, an amount of washing water consumed is very large when a soaking process is carried cut before the washing operation. 
     That is to say, the laundry must be soaked using only the washing water, and therefore, a large amount of washing water is needed. 
     Secondly, an additional structure for sterilizing the laundry is not provided. 
     Of course, although not shown, there has been proposed, in recent years, a washing machine including an additional heater for heating washing water such that laundry can be boiled. In this case, however, the sterilization of the laundry is accomplished only by the boiling operation. As a result, an amount of washing water and power necessary to boil the laundry is greatly increased. 
     Thirdly, the laundry is excessively wrinkled during the washing operation, and therefore, an additional manual operation, i.e., ironing of the laundry, is required, which is inconvenient. 
     Especially when the drying operation of the laundry is performed in the drum, although the laundry has many wrinkles, it is more difficult to iron the wrinkled laundry. This problem is a cause of many complaints from consumers. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a new type laundry machine that is capable of more rapidly and efficiently washing or drying laundry and, furthermore, accomplishing the wrinkle removal and sterilization of the laundry. 
     Technical Solution 
     The object of the present invention can be achieved by providing a steam generator comprising: a steam generation unit having a water inlet port formed at one side thereof, an outlet port formed at the other side thereof, and a flow channel connected between the water inlet port and the outlet port; and a heater for heating water being supplied through the water inlet port to generate steam. 
     The outlet port may be constructed such that only the steam can be discharged through the outlet port. The steam generation unit may be constructed such that the outlet port is disposed above the water inlet port on the basis of a horizontal line. The steam generation unit may be constructed such that the sectional area of the flow channel is greater than that of the water inlet port and that of the outlet port. The steam generation unit may be constructed such that the sectional area of the outlet port is less than that of the water inlet port. The steam generation unit may be made of a metal material having high thermal conductivity and low specific gravity. The steam generation unit may be manufactured by die casting. 
     The heater may be buried in the steam generation unit. In this case, the heater may be buried in an insert molding manner. The heater may be a sheath heater extending in the longitudinal direction of the flow channel. 
     The steam generator may further comprise: a water supply pipe for supplying water to the flow channel of the steam generation unit. The steam generator may further comprise: a discharge pipe for discharging the steam generated in the flow channel of the steam generation unit. The steam generator may further comprise: a temperature sensor for sensing the temperature of the steam generation unit. The steam generator may further comprise: an overflow pipe for discharging water overflowing from the flow channel when the water flowing through the flow channel overflows. 
     In another aspect of the present invention, provided herein is a laundry machine, comprising: a machine case forming the external appearance thereof; a drum rotatably mounted in the machine case; and a steam generator including a steam generation unit having a flow channel connected between a water inlet port formed at one side thereof and an outlet port formed at the other side thereof, and a heater for heating water being supplied through the water inlet port to generate steam. 
     The steam generator may be fixed to the machine case by means of separate brackets. 
     In a further aspect of the present invention, provided herein is a control method of a laundry machine including: a drum rotatably mounted therein; and a steam generator having a steam generation unit with a flow channel connected between a water inlet port formed at one side thereof and an cutlet port formed at the other side thereof, and a heater mounted in the steam generation unit, wherein the control method comprises: a steam supply step of heating water being supplied through the water inlet port of the steam generation unit by the heater to generate steam and supplying the generated steam to the drum. 
     The steam supply step may include: a first step of supplying water into the flow channel through the water inlet port; a second step of heating the water being supplied through the water inlet port to generate steam; and a third step of supplying the generated steam into the drum. The steam supply step may be carried out during a washing operation, during a drying operation, or after a drying operation. The drum may be rotated while the steam supply step is carried cut, and the steam may be supplied to the front upper side of the drum. 
     Advantageous Effects 
     The present invention has the following effects. 
     First, the present invention has the effect of improving the washing efficiency while reducing the consumption of the washing water during the washing operation. 
     Secondly, the present invention has the effect of reducing power consumption incurred to heat the washing water during the washing operation. 
     Thirdly, the present invention has the effect of improving the drying efficiency and the drying performance during the drying operation and accomplishing the wrinkle removal and sterilization of the laundry. 
     Fourthly, the present invention has the effect of refreshing the laundry, thereby improving the satisfaction of users. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention. 
       In the drawings: 
         FIG. 1  is a side view, in section, schematically illustrating the structure of a drum type washing-and-drying machine according to a preferred embodiment of the present invention. 
         FIG. 2  is a front view, in section, schematically illustrating the structure of the drum type washing-and-drying machine according to the preferred embodiment of the present invention. 
         FIG. 3  is a plan view schematically illustrating the structure of the drum type washing-and-drying machine according to the preferred embodiment of the present invention. 
         FIG. 4  is a perspective view schematically illustrating a steam generator of  FIG. 3 . 
         FIG. 5  is a sectional view taken along line I-I of  FIG. 4 . 
         FIG. 6  is a sectional view taken along line II-II of  FIG. 4 . 
         FIG. 7  is a front view, in section, schematically illustrating another example of a steam supply structure of the washing-and-drying machine according to the present invention. 
         FIG. 8  is a flow chart illustrating a control method of the washing-and-drying machine according to the preferred embodiment of the present invention. 
         FIG. 9  is a flow chart illustrating another example of a control method of the washing-and-drying machine according to the preferred embodiment of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT 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. In the following description, a laundry machine will be described on the assumption that the laundry machine is a drum type washing-and-drying machine. Of course, the laundry machine according to the present invention includes a general washing machine and a general drying machine. 
     As shown in  FIGS. 1 and 2 , a drum type washing-and-drying machine according to a preferred embodiment of the present invention includes a machine case  100  forming the external appearance thereof, a water supply valve  200  mounted to the machine case  100  for supplying water, a tub  300  mounted in the machine case  100 , the tub  300  having a hot air inlet port  310  and a hot air outlet port  320 , the tub  300  being formed approximately in the shape of a cylinder, a drum rotatably mounted in the tub  300 , a drying duct  500  having a drying heater  510  for heating air and a blowing fan  520  for blowing heated air, i.e., hot air, and at least one steam generator  600  for supplying steam into the tub  300 . 
     As shown in  FIGS. 3 to 6 , the steam generator  600  includes a steam generation unit  610 , a water supply pipe  620 , a discharge pipe  630 , and a heater  640 . 
     The steam generation unit  610  is provided at one side thereof with a water inlet port  612 , through which water is supplied, and is provided at the other side thereof with an outlet port  613 , through which steam is discharged. Between the water inlet port  612  and the outlet port  613  is formed a flow channel  611 . The water supply pipe  620  is disposed between the water supply valve  200  and the water inlet port  612  of the steam generation unit  610 . The discharge pipe  630  is disposed between the cutlet port  612  of the steam generation unit  610  and the tub  300 . The heater  640  heats water being supplied through the water inlet port  612  to generate steam. 
     In addition, the steam generator  600  further includes a temperature sensor (not shown) mounted in the steam generation unit  610  for sensing the temperature of steam generated in the flow channel  611  or the interior temperature of the flow channel  611 , and an overflow pipe  660  for discharging water overflowing from the flow channel  611  of the steam generation unit  610 . 
     Here, the temperature sensor is provided to control the heater  640  depending upon the steam temperature of the steam generation unit  610  or the interior temperature of the flow channel  611 , and it is preferable to use a thermofuse, which is broken, when the current temperature exceeds a predetermined level, to interrupt the current supplied to the heater  640 , and therefore, to prevent overheating of the heater  640 . 
     It is preferable that the overflow pipe  660  be disposed between a passage for allowing washing water to be introduced to the tub  300  through the water supply valve  200  and a water supply pipe  620 . 
     Specifically, as shown in  FIG. 3 , one end of the overflow pipe  660  is connected to a water feeding pipe  621 , and the other end of the overflow pipe  660  is connected to a connection pipe  710  connected between the detergent box  700  and the water supply valve  200 . 
     Here, when the end of the overflow pipe  660  is connected to the water feeding pipe  621 , the end of the overflow pipe  660  is connected to the lower part of the water feeding pipe  621  such that water overflowing from the flowing channel  611  of the steam generation unit  610  is directly discharged to the connection pipe  710  through the overflow pipe  600 . 
     In this case, it is preferable that the water feeding pipe  621  be disposed above the connection pipe  710 , whereby the water discharged to the connection pipe through the overflow pipe  660  is prevented from being introduced again into the water feeding pipe  621  through the overflow pipe  660 . 
     Of course, the water inlet port  612  and the outlet port  613  of the steam generation unit  610  are disposed opposite to each other about the flow channel  611 . In this case, the outlet port  613  is disposed above the water inlet port  612 . As a result, the water is prevented from being naturally discharged from the flow channel  611  of the steam generation unit  610  through the outlet port  613 . 
     In conclusion, it is preferable that the overflow pipe  660  is disposed below the water feeding pipe  621 , and the connection pipe  710  is disposed below the overflow pipe  660 . 
     Consequently, the water overflowing from the flow channel  611  of the steam generation unit  610  can be discharged to the connection pipe  710  through the overflow pipe  660  constructed as described above. 
     For example, when the heater  640  is turned off, or the operation of the steam generator  600  is interrupted, the water left in the flow channel  611  of the steam generation unit  610  may be supplied into the drum  400  through the cutlet port  613  even by small external impacts. 
     At this time, since the steam generator  600  is provided with the overflow pipe  660  constructed as described above, the water left in the flow channel  611  of the steam generation unit  610  is discharged to the connection pipe  710  through the overflow pipe  660 . 
     Consequently, even though the operation of the steam generator  600  is interrupted, the water left in the flow channel  611  of the steam generation unit  610  is prevented from being supplied into the drum  400 . 
     Of course, although not shown in the drawings, the overflow pipe  660  may be directly connected to the detergent box  700  such that the water overflowing from the flow channel  611  of the steam generation unit  610  can be directly discharged to the detergent box  700  through the overflow pipe  660 . 
     On the other hand, as shown in  FIGS. 4 to 6 , the steam generation unit  610  is formed in the shape of a pipe, and therefore; the flow channel  611  is also formed in the shape of a pipe. The water inlet port  612  and the outlet port  613  of the steam generation unit  610  are disposed opposite to each other at the opposite ends of the flow channel  611 . 
     Preferably, the steam generation unit  610  is disposed in an inclined state such that the outlet port  613  is positioned above the water inlet port  612  on the basis of the horizontal line, whereby water excluding steam is prevented from being discharged through the outlet port  613 . 
     At this time, the flow channel  611  of the steam generation unit  610  is formed such that the sectional area of the flow channel  611  is greater than that of the water supply pipe  620  and that of the discharge pipe  630 . Consequently, the supply of water to the flow channel  611  of the steam generation unit  610  and the discharge of steam from flow channel  611  of the steam generation unit  610  are more smoothly accomplished. 
     Specifically, since the sectional area of the flow channel  611  is greater than that of the water supply pipe  620 , the flow speed of water supplied from the water supply pipe  620  is decreased in the flow channel  611 . Consequently, the water flowing through the flow channel  611  can be evaporated by the heater  640  during a sufficiently extended period of time. 
     Also, since the sectional area of the discharge pipe  630  is less than that of the flow channel  611 , the flow speed of steam generated in the flow channel  611  is increased when the generated steam is introduced into the discharge pipe  630 . Consequently, the steam is rapidly supplied into the drum through the discharge pipe  630 . 
     Meanwhile, it is preferable that the steam generation unit  610  be made of a metal material having high thermal conductivity and low specific gravity, such as aluminum, and be manufactured by die casting. 
     Here, the die casting is a precision casing method of injecting a molten metal into a steel mold, which has been precisely machined such that the mold completely corresponds to a required casting shape, to obtain a product having the same shape of the mold. 
     Specifically, a molten metal (a metal material having high thermal conductivity and low specific gravity, such as aluminum) is injected into a steel mold, which has been precisely machined such that the mold completely corresponds to the shape of the steam generation unit  610 , whereby a desired steam generation unit  610  made of aluminum is manufactured. 
     When the steam generation unit  610  is manufactured by the die casting method, on the other hand, it is preferable to manufacture the steam generation unit in an insert molding manner such that the heater  640  is inserted into the steel mold provided for manufacturing the steam generation unit  610 , and the heater  640  is buried in the steam generation unit  610  (specifically, below the flow channel  611 ). 
     Consequently, the heater  640  is not mounted in the flow channel  611  of the steam generation unit  610 . The beater  640  is buried in the steam generation unit  610  at the position adjacent to the flow channel  611  outside the flow channel  611  such that water flowing through the flow channel  611  of the steam generation unit  610  can be indirectly heated by the heater  640 . 
     The water supply pipe  620  includes the water feeding pipe  621 , which is connected to the water supply valve  200  (see  FIG. 3 ), and a water inlet port connection pipe  622  connected between the water feeding pipe  621  and the water inlet port  612  of the steam generation unit  610 . 
     Also, the discharge pipe  630  includes an outlet port connection pipe  632  mounted to the outlet port  613  of the steam generation unit  610 , and a steam supply pipe  631  connected between the outlet port connection pipe  632  and the tub  300 . 
     Here, as shown in  FIG. 1 , it is preferable that one end  631   a  of the steam supply pipe  631 , through which steam is discharged, be formed in the shape of a nozzle, whereby smooth supply of steam is accomplished. 
     As shown in  FIG. 7 , on the other hand, steam generated by the steam generator  600  may be supplied to the drying duct  500  such that steam can be supplied into the drum  400  through the drying duct  500 . 
     Specifically, the steam supply pipe  631  is connected between the outlet port  613  of the steam generation unit  610  and the drying duct  500  such that steam can be supplied into the drum  400  through the drying duct  500 . 
     At this time, it is preferable that the end  631   a  of the steam supply pipe  631 , through which steam is discharged, be disposed at the hot air discharge side of the drying duct  500 . 
     Also, in the case that the steam discharged through the steam supply pipe  631  is supplied to the drying duct  500 , it is preferable to drive the blowing fan  520 , which is mounted in the drying duct  500 . 
     Consequently, the steam discharged through the steam supply pipe  631  is prevented from flowing backward in the direction opposite to the flow direction of the hot air in the drying duct  500 . 
     Of course, in the case that the steam discharged through the steam supply pipe  631  is supplied to the drying duct  500 , it is also possible to drive the blowing fan  520 , which is mounted in the drying duct  500 , and at the same time, to operate the drying heater  510  such that the steam supplied to the drying duct  500  can be introduced into the drum together with hot air. 
     Referring back to  FIGS. 4 to 6 , it is preferable to use a sheath heater, whose opposite ends are connected to a power source and whose heating part is formed approximately in the shape of a straight sheath, as the heater  640  of the steam generator  600 . 
     More specifically, when the steam generation unit  610  is manufactured by the die casting method as described above, the heater  640  is buried in the steam generation unit  610  in the insert molding manner. 
     At this time, the heater  640  is disposed outside the flow channel  611  of the steam generation unit  610  in the longitudinal direction of the flow channel  611 . 
     Specifically, the opposite ends of the heater  640  are exposed to the water inlet port  612  side of the steam generation unit  610  such that the opposite ends of the heater  640  are connected to the power source, and the heating part connected between the opposite ends of the heater  640  is bent at the outlet port  613  side of the steam generation unit  610 . Consequently, the heating part is arranged in the flow channel  611 , in a two-line pattern, along the flow direction of water. 
     At this time, it is preferable that the heating part of the heater  640  have a length extending in the longitudinal direction of the flow channel  611 , and the heating part be disposed adjacent to the flow channel  611 , whereby heat generated by heating of the heater  640  is more rapidly transferred to water flowing through the flow channel  611  via the steam generation unit  610 , which is made of aluminum as described above. 
     Consequently, water introduced into the flow channel  611  of the steam generation unit  610  is rapidly heated by the heater  640  while the water flows through the flow channel  611 , and therefore, the water is evaporated. 
     In this way, the steam generator  600  with the above-stated construction rapidly evaporates the water supplied from the water supply valve  200 , and then supplies the generated steam into the tub  300 . 
     On the other hand, as shown in  FIG. 3 , the steam generator  600  with the above-stated construction is fixed to the machine case  100 , which forms the external appearance of the drum type washing-and-drying machine, by means of separate brackets  810  and  820 . 
     Specifically, the machine case  100  of the drum type washing-and-drying machine is provided, with an auxiliary frame  810 , which extends in the front-and-rear direction of the machine case  100 , one side of the supporting bracket  820  is coupled to the front side of the auxiliary frame  810 , and the steam generation unit  610  is coupled to the other side of the supporting bracket  820 . As a result, the steam generator  600  is fixed to the machine case  100  of the drum type washing-and-drying machine. 
     At this time, it is preferable that the steam generation unit  610  be coupled to the other side of the supporting bracket  820  in a screw-coupling manner. 
     Specifically, although not shown in detail in the drawings, coupling bosses having coupling holes are formed at the upper surface of the steam generation unit  610  such that the coupling bosses protrude from the steam generation unit  610 . At the other side of the supporting bracket  820  are formed coupling holes, which correspond to the coupling bosses. Screws are threadedly inserted into the coupling bosses through the coupling holes. As a result, the steam generation unit  610  is coupled to the supporting bracket  820 . 
     For reference, the auxiliary frame  810  coupled to the machine case  100  serves to increase the strength of the machine case  100 . Consequently, the auxiliary frame  810  also serves to reduce vibrations and noises generated from the machine case  100  when a specific operation of the drum type washing-and-drying machine, for example, a spin-drying operation, is performed. 
     Hereinafter, a control method of the drum type washing-and-drying machine with the above-stated construction according to the preferred embodiment of the present invention mill be described. 
     First, a control method in a washing operation of the drum type washing-and-drying machine will be described. 
     When the washing operation of the drum type washing-and-drying machine is initiated, washing water and detergent are mixed in the detergent box  700 , and the washing water containing the detergent is introduced into the tub  300 . 
     At the same time, the steam generator  600  is operated, and water is supplied into the flow channel  611  through the water feeding pipe  621  and the water inlet port  612 . 
     At this time, the heater  640  heats water being supplied into the flow channel  611  through the water inlet port  612  to generate steam. 
     The generated steam is supplied to the front upper side of the tub  300  and the front upper side of the drum  400  through the outlet port  613  and the discharge pipe  630  of the steam generator  600 . 
     As the high-temperature steam is supplied into the drum  400  at the beginning of the washing operation as described above, laundry is smoothly soaked into the steam, and contaminants are smoothly separated from the laundry, whereby the washing efficiency is improved even with a small amount of washing water. 
     At this time, supply of the steam may be controlled based on either a predetermined period of time or a predetermined interior temperature of the drum or the tub. 
     Subsequently, the blowing fan  520  and the drying heater  510  are turned on such that hot air as well as the steam can be supplied into the drum  400 . As a result, the interior temperature of the drum  400  is increased, and therefore, the washing water in the drum  400  is heated, whereby the soaking of the laundry in the washing water and the separation of the contaminants from the laundry are more rapidly and efficiently accomplished. 
     On the other hand, the steam generator  600  may supply washing water into the drum  400  of the drum type washing-and-drying machine, instead of supplying steam into the drum  400 , whereby the washing operation time or the spin-drying operation time is reduced. 
     Specifically, when only washing water is needed instead of steam, the steam generator  600  is operated while the heater  640  is off. As a result, washing water is further supplied into the tub  300  through the steam generator  600 . 
     Consequently, washing water is supplied into the drum  400  through to water supply pipes respectively connected to the detergent box  700  and the steam generator  600 . As a result, the washing water supply time is reduced, and therefore, the total operation time is reduced. 
     Next, a control method in a drying operation of the drum type washing-and-drying machine will be described. 
     As shown in  FIG. 8 , when the drying operation of the drum type washing-and-drying machine is initiated, the drying heater  510  mounted in the drying duct  500  is turned on, and the blowing fan  520  is driven. As a result, hot air is generated in the drying duct  500 , and the generated hot air is supplied into the drum  400 . 
     At the same time, the steam generator  600  is operated, and water is supplied into the flow channel  611  through the water feeding pipe  621  and the water inlet port  612  (S 10 ). 
     At this time, the heater  640  heats water being supplied into the flow channel  611  through the water inlet port  612  to generate steam (S 20 ). 
     The generated steam is supplied to the front upper side of the tub  300  and the front upper side of the drum  400  through the cutlet port  613  and the discharge pipe  630  of the steam generator  600  (S 30 ). 
     Since the hot air is supplied into the drum  400  and, at the same time, the high-temperature steam is supplied into the drum  400  during the drying operation as described above, the interior temperature of the drum  400  is rapidly increased to a high level, and therefore, the drying efficiency of laundry is improved. 
     In addition, since the high-temperature steam is applied to the laundry, the wrinkles in the laundry are smoothed out, and the laundry is sterilized. Consequently, the refreshing effect of the laundry is also obtained. 
     At this time, the steam may be supplied for a period of time when the hot air is supplied into the drum  400 , or may be supplied for a predetermined period of time. Alternatively, the steam supply time may be controlled based on a predetermined interior temperature of the drum  400 . 
     On the other hand, as shown in  FIG. 7 , the steam generated by the steam generator  600  may be supplied into the drum  400  through the drying duct  500 , through which the hot air is supplied. 
     As shown in  FIG. 9 , the control method in the drying operation of the drum type washing-and-drying machine with the above-stated construction includes a water supply step (S 100 ), a steam generation step (S 200 ), a first steam supply step (S 300 ), and a second steam supply step (S 400 ). 
     The above-mentioned steps of the control method will be described below in detail. 
     When the drying operation of the drum type washing-and-drying machine is initiated, the drying heater  510  mounted in the drying duct  500  is turned on, and the blowing fan  520  is driven. As a result, hot air is generated in the drying duct  500 , and the generated hot air is supplied into the drum  400 . 
     At the same time, the steam generator  600  is operated, and water is supplied into the flow channel  611  through the water feeding pipe  621  and the water inlet port  612  (S 100 ). 
     At this time, the heater  640  heats water being supplied into the flow channel  611  through the water inlet port  612  to generate steam (S 200 ). 
     The generated steam is supplied into the drying duct  500  through the outlet port  613  and the discharge pipe  630  of the steam generator  600  (S 300 ). 
     The steam supplied into the drying duct  500  is introduced into the drum  400  together with the hot air flowing through the drying duct  500 . 
     At this time, the steam supplied into the drying duct  500  can be more rapidly introduced into the drum by the blowing force of the blowing fan  520 . 
     Since the hot air is supplied into the drum  400  and, at the same time, the high-temperature steam is supplied into the drum  400  daring the drying operation as described above, the interior temperature of the drum  400  is rapidly increased to a high level, and therefore, the drying efficiency of laundry is improved. 
     In addition, since the high-temperature steam is applied to the laundry, the wrinkles in the laundry are smoothed out, and the laundry is sterilized. Consequently, the refreshing effect of the laundry is also obtained. 
     At this time, the steam may be supplied for a period of time when the hot air is supplied into the drum  400 , or may be supplied for a predetermined period of time. Alternatively, the steam supply time may be controlled based on a predetermined interior temperature of the drum  400 . 
     Here, it is preferable that the steam supply be performed within the period of time when the hot air is supplied into the drum  400 . 
     If the steam is supplied into the drying duct  500  when the hot air flowing through the drying duct  500  does not flow to the drum  400 , the supplied steam flows backward in the direction opposite to the flow direction of the hot air in the drying duct  500 , and therefore, the drying heater  510  and the blowing fan  520  mounted in the drying duct  500  are wetted. As a result, the drying heater  510  and the blowing fan  520  malfunction. Consequently, the steam supply is performed within the above-specified period of time in order to prevent the malfunction of the drying heater  510  and the blowing fan  520 . 
     Subsequently, a control method in a refreshing operation of the drum type washing-and-drying machine, which is different from the washing operation and the drying operation of the drum type washing-and-drying machine, will be described. 
     When the refreshing operation of the drum type washing-and-drying machine is performed to smooth cut the wrinkles in laundry and sterilize the laundry in addition to the washing operation and the drying operation of the drum type washing-and-drying machine, the steam generator  600  generates high-temperature steam and supplies the generated steam into the drum  40  through the tub  300 . 
     Specifically, only high-temperature steam is applied to dried laundry or unwashed clothes without washing and drying the laundry such that the wrinkles in the laundry can be smoothed cut and the laundry can be sterilized. As a result, the laundry becomes soft and looks like new. 
     Consequently, the satisfaction of consumers is improved. 
     When the steam generator  600  is operated during the washing operation, the drying operation, and the refreshing operation of the drum type washing-and-drying machine as described above, it is preferable to rotate the drum  400  such that the steam generated by the steam generator  600  can be uniformly applied to the laundry. 
     Industrial Applicability 
     First, the present invention has the effect of improving the washing efficiency while reducing the consumption of the washing water during the washing operation. 
     Secondly, the present invention has the effect of reducing power consumption incurred to heat the washing water during the washing operation. 
     Thirdly, the present invention has the effect of improving the drying efficiency and, the drying performance during the drying operation and accomplishing the wrinkle removal and sterilization of the laundry. 
     Fourthly, the present invention has the effect of refreshing the laundry, thereby improving the satisfaction of users.