Patent Publication Number: US-8122547-B2

Title: Washing machine and method for controlling the same

Description:
This application claims the benefit of the Korean Application No. P2004-56202; P2004-56203 both filed on Jul. 20, 2004 and P2004-85321 filed on Oct. 25, 2004 which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a washing machine, and more particularly, to a washing machine and method for controlling the same, which are designed to save washing water and prevent damage of the laundry, which may be caused by temperature increase for the washing operation. 
     2. Discussion of the Related Art 
     Generally, a drum-type washing machine is a device performing the washing by dropping laundry loaded in a horizontally disposed drum. 
       FIG. 1  shows a prior drum-type washing machine and  FIG. 2  shows another prior drum-type washing machine. 
     Referring to  FIG. 1 , a drum-type washing machine includes a main body  10 , a tub  20  mounted in the main body  10 , a drum  30  rotatably mounted in the tub  20 , and a driving unit for driving the drum  30 . 
     Here, the main body  10  is provided at a front portion with a laundry loading opening  11 , around which a door  40  for opening/closing the opening  11  is mounted. 
     A gasket  50  is disposed on an inner circumference of the laundry loading opening  11  to provide a seal between the door  40  and the laundry loading opening  11 . 
     A damper  21  is provided on an outer-lower portion of the tub  20  and supported in the main body  10 . 
     The driving unit includes a driving motor  71  driving the drum  30  and a belt  72  connected to a belt pulley  73  to transmit driving force of the driving motor  71  to the drum  30 . 
     If the drum-type washing machine has a dry function, as shown in  FIG. 2 , a hot wind supply tube  81  is provided above the tub  20  and a dry heater  82  is disposed in the hot wind supply tube  81  to heat air flowing along the hot wind supply tube  81 . 
     Disposed on an air exhaust side of the hot wind supply tube  81  is a blower fan  83  for forcedly circulating the air. 
     However, in the prior drum-type washing machines, even when washing the laundry that is less stained and thus a little amount of water is required, a large amount of water is consumed. Furthermore, the washing operation is identically performed to a case for normal washing operation, increasing the consumption of the electricity. 
     Furthermore, in the case of the washing machine with the dry function, the laundry may be wrinkled or static electricity may occur. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a washing machine and method for controlling the same that substantially obviate one or more problems due to limitations and disadvantages of the related art. 
     An object of the present invention is to provide a washing machine and method for controlling the same, which are designed to save washing water and prevent damage of the laundry, which may be caused by temperature increase for the washing operation. 
     Another object of the present invention is to provide a washing machine and method for controlling the same, which can prevent the wrinkle of the laundry and the generation of the static electricity, which may be caused during the dry operation. 
     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a washing machine includes: a main body defining an outer appearance; a tub supported in the main body; a drum rotatably installed in the tub; a steam generating unit supplying steam into the drum; and a circulation pump returning washing water exhausted from a first side of the tub to a second side of the tub. 
     In another aspect of the present invention, there is provided a washing machine, including: a main body defining an outer appearance; a tub supported in the main body; a drum rotatably installed in the tub; a steam generating unit supplying steam into the drum; a circulation pump returning washing water exhausted from a first side of the tub to a second side of the tub; and a dry unit for drying laundry after washing operation is finished. 
     In a further another aspect of the present invention, there is provided a method for controlling a washing machine with a circulation pump circulating washing water and a steam generating unit, the method including the steps of supplying the washing water; increasing an inner temperature of a drum by supplying steam into the drum; repeating washing water supply/circulation process when the temperature is increased to a predetermined level; and repeating the above steps to gradually increase the inner temperature of the drum. 
     In a still further another aspect of the present invention, there is provided a method for controlling a washing machine with a circulation pump circulating washing water and a steam generating unit, the method including the steps of: supplying the washing water; increasing an inner temperature of a drum by supplying steam into the drum; detecting the inner temperature of the drum as the steam is supplied into the drum; comparing a detected temperature value with a reference temperature value; repeating a washing water circulation process after stopping a heating operation for generating the steam when the detected temperature value is identical to the reference temperature value; and repeating the above steps during a washing operation. 
     In a still yet another aspect of the present invention, there is provided a method for controlling a washing machine with a circulation pump circulating washing water and a steam generating unit, the method including the steps of: supplying the washing water; performing a heating operation for a predetermined time to direct the steam into the drum; repeating a washing water supply/circulation process after stopping the heating operation for generating the steam when the predetermined time has elapsed; and repeating the above steps during a washing operation. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
         FIG. 1  illustrates a prior drum-type washing machine; 
         FIG. 2  illustrates another prior drum-type washing machine; 
         FIGS. 3 and 4  illustrate an internal structure of a drum-type washing machine according to an embodiment of the present invention; 
         FIG. 5  illustrate an internal structure of a drum-type washing machine according to another embodiment of the present invention; 
         FIG. 6  illustrate an internal structure of a drum-type washing machine according to another embodiment of the present invention; 
         FIG. 7  illustrates an internal structure of a steam generating unit of a drum-type washing machine of the present invention; 
         FIG. 8  illustrates a graph showing a temperature variation in a drum during an washing operation of a drum-type washing machine of the present invention; and 
         FIG. 9  illustrates a flowchart of a method for controlling a drum-type washing machine of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIGS. 3 and 4  show a drum-type washing machine according to an embodiment of the present invention. 
     The inventive washing machine includes a main body  110  defining an outer appearance, a tub  120  disposed and supported in the main body  110 , a drum  130  rotatably installed in the tub  120 , one or more steam generating unit  200  providing a predetermined amount of steam into the drum  130 , and a circulation pump  400  circulating washing water exhausted from the tub  120  to a side of the tub  120 . 
     An opening of the drum  130  is oriented toward a laundry loading opening  111  of the main body  110 . 
     At this point, a door  140  for opening/closing the laundry loading opening  111  is mounted around the laundry loading opening  111  of the main body  110 . A gasket  150  is mounted on an inner circumference of the laundry loading opening  111  to provide a seal between the laundry loading opening  111  and the door  140 . 
     In addition, the drum  130  is provided with a plurality of through holes (not shown) so that washing water and steam can be introduced into the drum  130  through the through holes. 
     In the drum-type washing machine of the present invention, a dispenser  310  for supplying washing water into the tub  130  is connected to a water supply valve  118 . The steam generating unit  200  is also connected to the water supply valve  118 . 
     The water supply valve  118  is connected to a tap-water tube (not shown) to control of the supply of the tap-water. 
     The steam generating unit  200  is provided to hot washing water into the drum  130 . 
     The steam generating unit  200 , as shown in  FIG. 7 , includes a water storing tank  240  storing the water introduced through the water supply valve  118  and a heater  210  installed in the water storing tank  240  to vaporize the water by heating the water. 
       FIG. 7  shows an internal structure of the steam generating unit of the inventive drum-type washing machine. 
     The steam generating unit  200  includes a steam supply tube  220  supplying the steam generated by the heater  210  to the tub  120  and a first spray nozzle  230  provided on an end of the steam supply tube  220 . 
     At this point, the first spray nozzle  230  is formed in a nozzle-shape so that the steam can be effectively sprayed. An extreme end of the nozzle  230  is preferably exposed into the tube  120  by penetrating the tub  120 . 
     The steam supply tube  220  is located above the tub  120  such that the laundry loaded in the drum  130  may not directly contact the hot air. In this case, the steam supply tube  220  may be designed such that the steam can be directly directed into the drum  130  through the gasket  150  on the front portion of the tub  120 . 
     The heater  210  of the steam generating unit  200  may be of a coil heater wound around the steam supply tube  220  or, as shown in  FIG. 7 , of a sheath heater mounted in the water storing tank  240  to directly heat the water stored in the tank  240 . 
     When the sheath heater is used, a water level sensor for detecting the water level of the tank  240  is further provided. 
     That is, when the water level is not enough high, the heater  210  is excessively heated. When the water level is too high, the vaporizing time is increased. Furthermore, since liquid water may be sprayed, the water level should be maintained at a predetermined level. 
     That is, when the water level detected by the water level sensor  250  is higher than a reference level, the water supply to the tank  240  is stopped. When the water level detected by the water level sensor  250  is lower than the reference level, the water is supplied to the tank  240 . 
     Meanwhile, the volume of the steam generating unit  200  (i.e., the volume of the tank  240 ) to the volume of the drum  130  may be 1:1/30-1:1/120 so that a proper amount of steam can be supplied to the drum for the effective washing. 
     In order for the steam to be forcedly directed from the steam supply tube  220  into the drum  130 , the first spray nozzle  230  may be connected to a pumping unit such as a pump. However, by further providing an on/off valve  221  for turning on/off the steam supply tube  220  on the tube  220 , the steam can be selectively sprayed. 
     Meanwhile, the steam supply tube  220  has a bellows  220 &#39; to be stably fixed even when the vibration is transmitted from the tub  120  during the operation of the washing machine. The bellows  220 &#39; may be formed of rubber. 
     The steam supply tube  220  may be fastened on the tub  120  by a clamp  251 . 
     In addition, the dispenser  310  connected to the water supply valve  118  to supply the washing water into the tub  210  is provided in the main body  110 . The dispenser  310  is designed to add the detergent. 
     In addition, the dispenser  310  includes a second spray nozzle  330  spraying the stored detergent into the drum  130  and a detergent supply tube  320  guiding the detergent to the second spray nozzle  330 . 
     At this point, an extreme end of the second spray nozzle  330  may be exposed into the drum  130 . 
     The second spray nozzle  330  may be integrally formed with the first spray nozzle  230  of the steam generating unit  300 . 
     An amount of water supply per minute of the water supply valve  118  to the dispenser  310  is designed to be greater than an amount of water supply per minute of the water supply valve  118  to the steam generating unit  200 . 
     The circulating pump  400  is provided on the lower portion of the drum-type washing machine to circulate the water supplied. 
     A fluid circulating tube  410  for sucking the washing water exhausted to a lower portion of the tub  120  and directing the sucked washing water to the other side of the circulating pump  400  is disposed between the circulating pump  400  and the tub  120 . 
     That is, the circulating pump  400  pumps out the washing water introduced. The washing water pumped out by the circulating pump  400  is directed into the tub  120  through a front-upper portion of the tub  120 , ascending along the fluid circulating tube  410 . 
     By directing the washing water accumulated on the bottom of the tub  120  into the drum  130 , the laundry can be uniformly wet and washing water can be saved. 
     In this case, a filter (not shown) for filtering foreign objects contained in the washing water may be further provided on the circulating pump  400  or the fluid circulating tube  410 . 
     A drain pump (not shown) for draining the washing water after the washing and rinsing cycles are completed is installed on a lower portion of the washing machine. 
       FIG. 5  shows a structure for effectively separating the polluting substances from the laundry socked in the washing water by the washing machine with the steam generating unit according to the present invention. 
     The structure depicted in  FIG. 5  is identical to that depicted in  FIGS. 3 and 4  except that a heater  500  is provided under the tub  120  to boil the laundry. 
     In this case, the heater  500  functions to boil the laundry by heating the washing water supplied to the tub, thereby effectively separating the polluting substances from the laundry by cooperating with the steam generating unit  200 . 
     A washing machine having the above-described structure but further having a dry function will be described hereinafter. 
       FIG. 6  shows a drum-type washing machine according to another embodiment of the present invention. 
     A washing machine includes a main body  110  defining an outer appearance, a tub  120  disposed and supported in the main body  110 , a drum  130  rotatably installed in the tub  120  and provided with a plurality of through holes, one or more steam generating unit  200  providing a predetermined amount of steam into the drum  130 , a circulation pump  400  circulating washing water exhausted from the tub  120  to a side of the tub  120 , and a dry unit for drying the laundry after the washing/rinsing operation is finished. 
     An opening of the drum  130  is oriented toward a laundry loading opening  111  of the main body  110 . 
     At this point, a door  140  for opening/closing the laundry loading opening  111  is mounted around the laundry loading opening  111  of the main body  110 . A gasket  150  is mounted on an inner circumference of the laundry loading opening  111  to provide a seal between the laundry loading opening  111  and the door  140 . 
     In addition, the drum  130  is provided with a plurality of through holes (not shown) so that washing water and steam can be introduced into the drum  130  through the through holes. 
     In the drum-type washing machine of the present invention, a dispenser  310  for supplying washing water and steam into the tub  130  is connected to a water supply valve  118 . The steam generating unit  200  is also connected to the water supply valve  118 . 
     The water supply valve  118  is connected to a tap-water tube (not shown) to control of the supply of the tap-water. 
     The water supply valve  118  is designed to simultaneously supply the water to both the steam generating unit  200  and the dispenser  310  or to selectively supply the water to one of the steam generating unit  200  and the dispenser  310 . 
     The steam generating unit  200  is provided to hot washing water into the drum  130 . 
     The steam generating unit  200 , as shown in  FIG. 7 , includes a water storing tank  240  storing the water introduced through the water supply valve  118  and a heater  210  installed in the water storing tank  240  to vaporize the water by heating the water. 
       FIG. 7  shows an internal structure of the steam generating unit of the inventive drum-type washing machine. 
     The steam generating unit  200  includes a steam supply tube  220  supplying the steam generated by the heater  210  to the tub  120  and a first spray nozzle  230  provided on an end of the steam supply tube  220 . 
     At this point, the first spray nozzle  230  is formed in a nozzle-shape so that the steam can be effectively sprayed. An extreme end of the nozzle  230  is preferably exposed into the tube  120  by penetrating the tub  120 . 
     The steam supply tube  220  is located above the tub  120  such that the laundry loaded in the drum  130  may not directly contact the hot air. In this case, the steam supply tube  220  may be designed such that the steam can be directly directed into the drum  130  through the gasket  150  on the front portion of the tub  120 . 
     In order for the steam to be forcedly directed from the steam supply tube  220  into the drum  130 , the first spray nozzle  230  may be connected to a pumping unit such as a pump. However, by further providing a first on/off valve  221  for opening and closing the steam supply tube  220  on the tube  220 , the steam can be selectively sprayed. 
     At this point, a first side of the water storing tank  240  is connected to the water supply valve  118  connected to a tap-water pipe and a second side of the water storing tank  240  is connected to the steam supply tube  220 . 
     The heater  210  of the steam generating unit  200  may be of a coil heater wound around the steam supply tube  220  or a sheath heater mounted in the water storing tank  240  to directly heat the water stored in the tank  240 . 
     When the sheath heater is used, a water level sensor  250  for detecting the water level of the tank  240  is further provided in the steam generating unit  200  as shown in  FIG. 7 . 
     That is, when the water level is not enough high, the heater  210  is excessively heated. When the water level is too high, the vaporizing time is increased. Furthermore, since liquid water may be sprayed, the water level should be maintained at a predetermined level. 
     That is, when the water level detected by the water level sensor  250  is higher than a reference level, the water supply to the tank  240  is stopped. When the water level detected by the water level sensor  250  is lower than the reference level, the water is supplied to the tank  240 . 
     Meanwhile, the volume of the steam generating unit  200  (i.e., the volume of the tank  240 ) to the volume of the drum  130  may be 1:1/30-1:1/120 so that a proper amount of steam can be supplied to the drum for the effective washing. 
     In order for the steam to be forcedly directed from the steam supply tube  220  into the drum  130 , the first spray nozzle  230  may be connected to a pumping unit such as a pump. However, by further providing an on/off valve  221  for turning on/off the steam supply tube  220  on the tube  220 , the steam can be selectively sprayed. 
     Meanwhile, as shown in  FIG. 6 , the steam supply tube  220  has a bellows  220 ′ to be stably fixed even when the vibration is transmitted from the tub  120  during the operation of the washing machine. The bellows  220 ′ may be formed of rubber. 
     The steam supply tube  220  may be fastened on the tub  120  by a clamp  251 . 
     In addition, the dispenser  310  connected to the water supply valve  118  to supply the washing water into the tub  210  is provided in the main body  110 . The dispenser  310  is designed to add the detergent. 
     In addition, the dispenser  310  includes a second spray nozzle  330  spraying the stored detergent into the drum  130  and a detergent supply tube  320  guiding the detergent to the second spray nozzle  330 . 
     At this point, an extreme end of the second spray nozzle  330  may be exposed into the drum  130 . 
     More preferably, the extreme end of the second spray nozzle  330  is exposed into the drum  130 , penetrating a portion (i.e., the gasket) through which the laundry is loaded in the drum. 
     In order for the detergent to be forcedly directed from the dispenser  310  into the drum  130 , the second spray nozzle  330  may be connected to a pumping unit such as a pump. However, by further providing an on/off valve  221  for opening/closing the detergent supply tube  320  on the tube  320 , the detergent can be selectively supplied. 
     The second spray nozzle  330  may be integrally formed with the first spray nozzle  230  of the steam generating unit  300 . 
     An amount of water supply per minute of the water supply valve  118  to the dispenser  310  is designed to be greater than an amount of water supply per minute of the water supply valve  118  to the steam generating unit  200 . 
     The circulating pump  400  is provided on the lower portion of the drum-type washing machine to circulate the water supplied. 
     A fluid circulating tube  410  for sucking the washing water exhausted to a lower portion of the tub  120  and directing the sucked washing water to the other side of the circulating pump  400  is disposed between the circulating pump  400  and the tub  120 . 
     That is, the circulating pump  400  pumps out the washing water introduced. The washing water pumped out by the circulating pump  400  is directed into the tub  120  through a front-upper portion of the tub  120 , ascending along the fluid circulating tube  410 . 
     By directing the washing water accumulated on the bottom of the tub  120  into the drum  130 , the laundry can be uniformly wet and washing water can be saved. 
     In this case, a filter (not shown) for filtering foreign objects contained in the washing water may be further provided on the circulating pump  400  or the fluid circulating tube  410 . 
     A drain pump (not shown) for draining the washing water after the washing and rinsing cycles are completed is installed on a lower portion of the washing machine. 
     The drum-type washing machine of this embodiment further includes the dry unit. The dry unit includes a hot wind supply tube  181  supplying high temperature/dry air into the drum  130  and a dry heater  182  heating the air flowing along the hot wind supply tube  181 . 
     At this point, a flower fan  183  is provided on the hot wind supply tube  181  to forcedly direct the air out of the hot wind supply tube  181 . 
     The operation and control method of the above-described washing machine will be described hereinafter. 
       FIG. 8  shows a graph showing a temperature variation in a drum during a washing operation of a drum-type washing machine of the present invention and  FIG. 9  illustrates a flowchart of a method for controlling a drum-type washing machine of the present invention. 
     When a user input a control signal to perform the washing cycle after loading the laundry into the drum, water is supplied into the tub  120  through the dispenser  310  to initiate the washing operation (S 601 ). 
     When the water supply is completed (S 602 ), the steam generating unit  200  is operated to supply the high temperature/high pressure steam into the drum  130  for a predetermined time (a) to soak the laundry (S 603 ). 
     In this case, as shown in  FIG. 8 , the temperature in the drum  130  is gradually increased to T 1  by the steam supplied. 
     Here, the heating for supplying the steam is continued until a current detected temperature value T 1  meets a first reference temperature value T 1 ref by detecting the internal temperature of the drum (S 640 ) and comparing the first reference temperature value T 1 ref with the detected temperature value T 1  (S 604 ). 
     When the current detected temperature value meets the first reference temperature value T 1 ref, the steam supply is stopped and the washing water is supplied again through the dispenser  310 . The washing water supplied is circulated couple of times by the circulating pump  400  and then drained (S 606 ). 
     Since the washing water supplied is cool water for a time (a-a 1 ) in the graph at which the water circulation/drain process is performed, the internal temperature of the drum  130  is reduced. 
     After the above, the steam generating unit  200  is operated again to supply the steam into the drum  130  for a predetermined time (a 1 -b) to increase the temperature to T 2  (S 607 ). 
     That is, the internal temperature of the drum is detected (S 608 ) and a second reference temperature value T 2 ref is compared with the detected temperature value T 2 (S 609 ). The heating is continued until the detected temperature value T 2  becomes identical to the second reference temperature value T 2 ref. 
     When the detected temperature value T 2  becomes identical to the second reference temperature value T 2 ref, the water circulation/drain process is performed for a predetermined time (a 1 -b). 
     The above described process is repeated by n times as shown in  FIG. 8 , in the course of which the internal temperature of the drum is repeatedly increased and reduced. 
     In the final step of the washing operation, more amount of washing water than that of the foregoing steps to finally separate the stain from the laundry by being circulated by the circulation pump  400  and is then drained (S 610 ). 
     When only the steam is continuously supplied for a predetermined time without the water circulation and supply process, the laundry may be damaged as the internal temperature of the drum is excessively increased. Therefore, in the present invention, the steam supply process and the water circulation/drain process are alternately performed to prevent the internal temperature in the drum is increased too high. 
     Since the temperature is designed to gradually slowly increased and a small amount of water is supplied and circulated during the washing operation, the washing water as well as the electricity can be saved. 
     In this case, it is preferable that the drum is rotated with low speed during the steam supply from the steam generating unit  200  in order to maximize the stain separation and soaking effect. 
     After the above-described washing processes are all finished, drain, rinsing (S 611 ) and spinning (S 612 ) cycles are processed. 
     When the washing machine has the dry function as shown in  FIG. 6 , the dry cycle is started after the spinning cycle (S 612 ) is finished (S 613 ). 
     That is, when the dry cycle is started, electric power is applied to the dry heater  182  in the hot wind supply tube  181 . 
     At this point, the blower fan  183  forcedly ventilates the hot wind as the heater is operated. 
     The hot wind is directed into the tub  120  by being guided by the hot wind supply tube  181  and is then directed to the drum  130  through the through holes (not shown). 
     The hot wind fed to the drum  130  heats the laundry to vaporize the water contained in the laundry, in the course of which the drum  130  rotates with low speed to agitate the laundry, thereby uniformly heating the laundry and enhancing the vaporize of the water. 
     The vaporized water is mixed with air and exhausted to be dried. The dried air is introduced into the hot wind supply tube  181  again. This process is repeated to dry the laundry. 
     During the dry cycle, a predetermined amount of steam may be supplied using the steam generating unit in order to prevent the laundry from being wrinkled and to obtain the static electricity elimination effect. 
     As described above, by alternately repeating the steam supply process and the water circulation/drain process, the internal temperature of the drum is gradually increased to prevent the laundry from being damaged and effectively separate the stain from the laundry. 
     Therefore, it is required to set a repeating section of the steam supply process and the water circulation/drain process. In  FIG. 9 , a method for setting the repeating section by detecting the internal temperature of the drum and comparing the detected temperature with the reference temperature value is illustrated. 
     Alternatively, a heating time for supplying the steam may be preset, based on which the steam supply process and the water circulation/drain process are alternately repeated to gradually increase the internal temperature of the drum. 
     The heating times at each heating section may be preset to be identical with each other or may be preset to be gradually increased. 
     The above-described inventive drum-type washing machine has advantages as follows: 
     1. The washing water and electricity can be saved. 
     2. Since the steam supply process and the water circulation/drain process are alternately performed, the damage of the laundry, which may be caused by the excessively increased internal temperature of the drum, can be prevented and the stain separation from the laundry can be improved. 
     3. By supplying a predetermined amount of steam to the drum during the dry operation, the wrinkle of the laundry and the generation of the static electricity can be prevented. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.