Patent Publication Number: US-2006005319-A1

Title: Washing machine and dehydrating method thereof

Description:
This application claims the benefit of Korean Application No. P2004-53125, filed on Jul. 8, 2004, which is hereby incorporated by reference as if fully set forth herein.  
     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 a dehydrating method thereof enabling to smoothly and stably drain water during dehydration and a dehydrating method.  
      2. Discussion of the Related Art  
      A washing machine is an apparatus for removing contaminants stained on a laundry using functions of detergent and water. Such washing machine is classified into many kinds according to a method of applying impact to the laundry.  
      A drum washing machine removes contaminants by rotating a drum so as to drop the laundry and apply impact thereto. A pulsator washing machine removes contaminants using a driving axis vertically mounted therein, and water current generated by rotation of a pulsator coupled with the driving axis.  
      When the drum washing machine carries out dehydration and the drum is rotated in a tub at a high speed, airflow is generated by the rotation of the drum. Due to the airflow, a problem is generated that water in the tub moves along an inner wall surface of the tub without being discharged to an outside of the tub and flows back into the drum.  
      In addition, when the dehydration is completed and the speed of the drum is reduced, a problem is generated that the moving water flows into the drum and wets the laundry.  
     SUMMARY OF THE INVENTION  
      Accordingly, the present invention is directed to a washing machine and a dehydrating method of the same 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 washing machine and a dehydrating method thereof enabling to smoothly and stably drain water during dehydration.  
      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, a washing machine includes a tub, a drum rotatably mounted in the tub, and a controller for rotating the drum at a high speed when the laundry is dehydrated, and controlling the drum to be rotated during the high speed rotation at a low speed at least N times so as to prevent the water from being interfered with by an airflow generated during the high speed rotation of the drum and to stably drain water.  
      A dehydrating method for a washing machine includes the steps of rotating a drum provided in a tub at a high speed so as to dehydrate laundry, and rotating the drum during the high speed rotation at a low speed at least N times so as to prevent the water from being interfered with by an airflow generated during the high speed rotation of the drum and to stably drain water.  
      In another aspect of the present invention, a washing machine includes a tub, a drum rotatably mounted in the tub, and a controller for controlling the drum so as to perform an untangling step for untangling the laundry by rotating the drum, a balancing step for distributing the laundry evenly in the drum by rotating the drum at a first speed, a dehydrating step for removing water from the laundry in the drum by rotating the drum at a second speed being faster than the first speed, during the dehydrating step, a draining step for smoothly and stably draining water to an outside of the tub, the water dehydrated to the tub, by rotating the drum at least N times at a third speed slower than the second speed.  
      A dehydrating method of the washing machine in accordance with a second embodiment of the present invention includes the steps of rotating a drum to untangle laundry within the drum, rotating the drum at a first speed so as to evenly distribute the laundry within the drum, rotating the drum at a second speed higher than the first speed to dehydrate the laundry, and, rotating the drum at a third speed lower than the second speed at least N times so as to stably drain the water from a tub.  
      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 cross sectional view of a washing machine in accordance with the present invention,  
       FIG. 2  illustrates a block diagram of the washing machine in accordance with the present invention,  
       FIG. 3  illustrates a flow chart of a dehydrating method in accordance with a first embodiment of the present invention,  
       FIG. 4  illustrates a flow chart of a dehydrating method in accordance with a second embodiment of the present invention,  
       FIG. 5  illustrates a graph showing speed of a drum in accordance with the present invention, and  
       FIG. 6  illustrates a graph showing the speed of the drum in accordance with 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.  
      Referring to  FIG. 3 , the exterior of a washing machine  100  in accordance with the present invention includes a case  110 . A tub  120  is suspended from the case  110 . For this reason, an upper part of the tub  120  is coupled with a damper  150  hinge-coupled with a floor surface of the case  110 . A spring  140  and a damper  150  provided as mentioned above not only carry out a role of elastically suspending the tub  120  from the case  110  but also reducing vibration applied to the tub  120  during the operation of the washing machine.  
      The drum  130  has a plurality of through holes  131  on an outer circumferential surface, and a plurality of tumbling ribs  132  on an inner circumferential surface. Accordingly, during washing, water supplied in the tub  120  moves between the drum  130  and the tub  120  through the through holes  131 .  
      In addition, when the drum  130  is rotated, wash water put into the drum  130  is lifted up and dropped down by the tumbling rib  132 . Accordingly, a large amount of friction and impact energy needed for washing are obtained when the laundry is dropped down by the tumbling rib  132 .  
      Meanwhile, on a front surface of the case  110 , an opening  111  is provided for a user to put or take out the laundry into/from the drum  130 , and a door  122  is provided for opening or closing the opening  111 . Between the opening  111  of the case  110  and the tub  120 , a gasket  113  is provided for preventing water and the laundry in the drum  130  and the tub  120  from leaking.  
      Besides, a supplying device  160  and a draining device  170  are provided in the case  110 . The supplying device  160  includes a supply valve  161 , a supply hose  162 , a detergent box  163 , and a supply bellows  164 . The supply valve  161  opens or closes a channel of water supplied from the outside thereof, and the supply hose  162  couples the supply valve  161  with the detergent box  163 . The supply bellows  164  couples the detergent box  163  with the tub  120 . Accordingly, when the supply valve  161  is opened, water passes through the supply hose  162 , the detergent box  163 , and the supply bellows  164 , and then is supplied into the tub  120 . In this instance, the detergent stored in the detergent box  163  is supplied to the water at need.  
      The draining device  170  includes a drain bellows  171 , a drain pump  172 , and a drain hose  173 . In this case, the drain bellows  171  couples the tub  120  with the drain pump  172 . A first end of the drain hose  173  is coupled with the drain pump  172 , and a second end thereof is communicated with the outside of the case  110 . Accordingly, when the drain pup  172  starts operating, the water in the tub  120  passes through the drain bellows  171 , the drain pump  172 , and the drain hose  173 , and then discharged outside.  
      Meanwhile, to rotate the drum  130 , a motor  180  is provided in the case  110 , more particularly under the tub  120 . A pulley  200  and a driving force transmitting member  190  are provided for transmitting a turning force of the motor  180  to the drum  130 . The pulley  200  is coupled with an axis  133  formed at a rear of the drum  130  so as to provide the turning force to the drum  130 , the turning force generated from the motor  180 , and coupled with the motor  180  via the driving force transmitting member  190 . In this case, the driving force transmitting member  190  includes a belt.  
      In addition, the washing machine  100 , though not illustrated in  FIG. 1 , includes a controller  300  for controlling each part of the washing machine  100  by calculating commands inputted from a key input unit  400  for inputting commands of a user. Particularly, the controller  300  controls rotation frequency of the drum  130  by controlling the motor  180 . Hereinafter, the key input unit  400  and the controller  300  will be described in more detail.  
      The key input unit  400  is generally located at an upper part of the washing machine  100 , and includes an input device such as a button for a user to input. The key input unit  400  further includes a display member (not shown) for showing a user the current state of the washing machine  100 . In this case, the state of the washing machine  100  indicates an operating state, such as washing or dehydration, of the washing machine.  
      The controller  300  is mounted in the case. The controller  300  performs a washing or dehydrating by controlling each part of the washing machine  100 . To do this, the controller  300  is electrically coupled with each part of the washing machine  100  so as to receive commands inputted from the key input unit  400  by the user and perform the commands inputted by controlling each part of the washing machine  100 . In this case, the washing machine  100  includes the motor  180 , a drum  130 , a supplying device  160 , a draining device  170 , an eccentricity measuring unit  320 , and a speed sensing unit  310 .  
      The eccentricity measuring unit  320  measures an amount of eccentricity of the drum  130 , and reports to the controller  300 . The speed sensing unit  310  measures the rotation speed of the drum  130  and reports to the controller  300 .  
      In this case, the eccentricity measuring unit  320  and the speed sensing unit  310  are mounted in the case, more particularly at one of the tub  120 , the drum  130  and the motor  180 . The controller  300  determines information measured at the speed sensing unit  310  so as to control the rotation speed of the drum  130 .  
      Meanwhile, the controller  300  performs the washing and dehydrating methods as mentioned above. Hereinafter, the dehydrating method will be described in more detail.  
       FIG. 3  illustrates a dehydrating method of a washing machine  100  in accordance with the present invention. Referring to  FIG. 3 , the dehydrating method of the washing machine  100  includes the step S 10 , S 30  of rotating the drum  130  at a high speed so as to dehydrate the laundry, and the step S 20  of rotating the drum N times at a low speed so as to stably drain the water dehydrated from the laundry to the outside of the tub  120 .  
      In other words, the controller  300  rotates S 10  the drum  130  at a high speed so as to dehydrate the laundry remaining in the drum  130 . The water contained in the laundry is moved from the drum  130  to the tub  120  through the through the hole  131 .  
      In this case, the drum  130  is rotated at a speed for dehydrating the laundry. In more detail, the drum  130  at the high speed is rotated at a speed more than 300 rpm and less than 450 rpm.  
      Meanwhile, when the drum  130  is rotated at the high speed, the water dehydrated to the tub  120  is not drained but moved along an inner wall surface of the tub  120  due to the airflow generated when the drum  130  is rotated. The water flows back into the drum  130  and wets the laundry when the rotation of drum is stopped or the rotation speed of the drum is reduced.  
      Accordingly, the drum  130  is rotated S 20  N times at the low speed in the process of rotating the drum  130  at the high speed. In this case, the speed of the drum  130  is set at a speed of minimizing airflow generated when the drum  130  is rotated. Then, the water being flowed along the inner wall surface of the tub  120  is not interfered by the airflow but smoothly and stably collected at a lower part of the tub  120  and then drained outside of the tub  120 . In other words, when the controller  300 , during the dehydration of the laundry, rotates the drum  130  at a low speed at least one time in the middle of rotating the drum  130  at the high speed.  
      The airflow generated when the drum  130  is rotated is minimized, and due to the gravity, the water being flowed along the inner wall surface of the tub  120  is smoothly and stably gathered at the lower part of the tub  120 , and then drained outside of the tub  120 . In this case, the controller  300  sets the rotation speed of the drum  130  at a speed of minimizing the airflow generated when the drum  130  is rotated. Then, the water being flowed along the inner wall surface of the tub  120  is not interfered by the airflow but smoothly and stably gathered at a lower part of the tub  120  and then drained outside of the tub  120 .  
      Meanwhile, when the drum  130  is rotated at the low speed, the laundry needs to be stuck to the inner wall surface of the drum  130  by centrifugal force. If the laundry is not stuck to the inner wall surface of the drum  130 , an eccentric amount of the drum  130  is increased. Accordingly, the laundry is hit against the inner wall surface of the tub  120  when the drum  130  is rotated.  
      In other words, the controller  300  rotates the drum  130  at a speed at which the laundry kept being attached on the inner wall surface of the drum  130  by the centrifugal force. In this case, the drum  130  is rotated at a speed more than 100 rpm and less than 150 rpm. The drum  130  is then rotated at a high speed so as to remove the water remained in the laundry.  
      In the mean time, a frequency of performing the step S 20  of rotating the drum  130  at the low speed is determined by at least one of three factors such as a laundry amount, a water amount and a dehydration degree. In other words, the controller  300  determines the frequency for performing the drum  130  at the low speed by referring to one of the laundry amount, the water amount and the dehydration degree.  
      A time of performing the step S 20  of rotating the drum  130  at the low speed is determined by at least one of three factors such as the laundry amount, the water amount and the dehydration degree. In other words, the controller  300  determines the time of rotating the drum  130  by referring to one of the laundry amount, the water amount and the dehydration degree.  
      At the step S 20  of rotating the drum  130  at the low speed, a rotation speed of the drum  130  is determined by one of the laundry amount, the water amount and the dehydration degree. In other words, the controller  300  determines the rotation speed of the drum  130  by referring to one of the laundry amount, the water amount and the dehydration degree.  
      At the step S 20  of rotating the drum  130  at a low speed, one of the performing frequency, the performing time and the rotation speed is determined by one of three factors such as the laundry amount, the water amount, and the dehydration degree.  
      In other words, the controller  300  may determine the rotation frequency of the drum  130  rotated at a low speed, considering other factors except the laundry amount and the dehydration degree. In this case, other factors may be the size of the drum  130 , the capacity of the washing machine  100 , and the kind of the laundry.  
      Otherwise, at the step S 20  of rotating the drum  130 , at least one of N, a time for performing each low speed rotation and the low speed is determined based on weight of the laundry. In this case, the controller  300  determines at least one of N, a time for performing each low speed rotation and the low speed of the drum  130  by referring to the weight of laundry. In here, the weight of laundry is a weight in an early stage of the step S 10  of rotating the drum  130  at the high speed.  
      Otherwise, at the step S 20  of rotating the drum  130 , at least one of N, a time for performing each low speed rotation and the low speed is determined based on a change in weight of laundry. In this case, the controller  300  determines at least one of N, a time for performing each low speed rotation and the low speed of the drum  130  by referring to the change in weight of the laundry. In here, the change in weight of the laundry is difference between a weight in an early stage of the step S 10  of rotating the drum  130  at the high speed and a weight after the step S 20  of rotating the drum  130  at a low speed.  
       FIG. 4  illustrates a dehydrating method of the washing machine  100  in accordance with a second embodiment of the present invention.  FIG. 5  and  FIG. 6  illustrate speed of the drum  130  in the washing machine  100  in accordance with the second embodiment of the present invention. Hereinafter, the second embodiment of the present invention will be described using appended drawings.  
      An untangling step S 100  for untangling the laundry is carried out by rotating the drum  130 . In this case, the untangling step S 100  is for untangling the tangled laundry after washing, so as to distribute the laundry evenly on the inner wall surface. Accordingly, the controller  300  rotates the drum  130  at a speed (for example, 50 rpm) at which the laundry is raised along the inner wall surface and then dropped.  
      After the untangling step S 100 , a balancing step S 200  is carried out for distributing the laundry evenly inside of the drum  130  by rotating the drum  130 . In the balancing step, the controller  300  rotates the drum  130  at a first speed faster than at the untangling step S 100 . The controller  300  also rotates the drum  130  for a predetermined time at a predetermined speed (for example 110 rpm) so as to evenly distribute the laundry on the inner wall surface of the drum  130 , thereby balancing the drum  130 .  
      In the balancing step S 200 , the eccentricity measuring unit  320  measures the eccentric amount of the drum  130 . The controller also controls the rotation speed of the drum  130  by comparing the eccentric amount of the drum  130 , measured at the eccentricity measuring unit  320 , with a standard eccentric amount.  
      In more detail, the controller  300  repeatedly carries out the balancing step when the measured eccentric amount of the drum  130  is larger than the standard eccentric amount, and carries out a next step S 300  when the eccentric amount of the drum  130  is smaller than the standard eccentric amount.  
      After the balancing step S 200 , a dehydrating step S 500 , S 700  is carried out for removing water in the drum  130  by rotating the drum  130  at a second speed faster than the first speed that is the rotation speed of the balancing step S 200 . In the early stage of the dehydrating step, a large amount of water is dehydrated at a time, a noise is generated, and therefore the motor  180  is overloaded. Accordingly, prior to the dehydrating step, a simple dehydrating step S 400  is carried out for slowly or gradually accelerating the drum  130  for a predetermined time.  
      In the dehydrating step S 500 , the drum  130  is rotated at a speed enabling smooth dehydration of the laundry. In more detail, the drum  130  is rotated at a speed greater than 300 rpm and less than 450 rpm. In this instance, the water contained in the laundry is eccentrically dehydrated and then drained to the tub  120  through the through the hole  131  of the drum  130 .  
      Meanwhile, due to the airflow generated when the drum  120  is rotated, the water dehydrated to the tub  120  is not drained but moved along the inner wall surface of the tub  120 . When the drum  130  stops rotating or reduces the rotation speed thereof, water is flowed into the drum  130  and wets the laundry.  
      Accordingly, during the dehydrating step S 500 , a draining step S 600  is carried out by rotating the drum  130  at a third speed slower than the second speed that is the rotation speed of the dehydrating step S 500 , so as to smoothly and stably flow the water to the outside of the tub  120 , the water dehydrated to the tub  120 .  
      In the draining step S 600 , the drum  130  is rotated at the third speed that is a speed at which the airflow generated during rotation of the drum is minimized. Then, the water flowing along the inner wall surface of the tub  120  is gathered at a lower part of the tub  120 , and drained to the outside of the tub  120   
      In other words, the controller  300  rotates the drum  130  at the third speed lower than the second speed that of the dehydrating step S 500 , and thus reduces the rotation speed of the drum  130  at the draining step S 600 . In other words, the speed of the drum  130  is reduced. Then, the airflow generated when the drum  130  is rotated is minimized, and the water being flowed along the inner wall surface of the tub  120  is smoothly and stably gathered at a lower part of the tub  120  and drained outside thereof.  
      Meanwhile, at the draining step S 600 , the controller  300  rotates the drum  130  at a speed at which the airflow generated when the drum  130  is rotated is minimized. Then, the water being flowed along the inner wall surface of the tub  120  is not interfered by the airflow but smoothly and stably gathered at a lower part of the tub  120  and then drained outside of the tub  120 .  
      At the draining step S 600 , the laundry needs to be stuck to the inner surface of the drum  130  by centrifugal force. If the laundry is not stuck to the inner wall surface of the drum  130 , the eccentric amount of the drum  130  is increased. Accordingly, the laundry is hit against the inner wall surface of the tub  120  when the drum  130  is rotated.  
      In other words, the controller  300  rotates the drum  130  at a speed at which the laundry kept being attached on the inner wall surface of the drum  130  by the centrifugal force. In this case, the drum  130  is rotated at a speed more than 100 rpm and less than 150 rpm. The drum  130  is then rotated at a high speed so as to remove the remaining laundry.  
      Meanwhile, a frequency of performing the draining step S 600  is determined by at least one of three factors such as the laundry amount, the water amount and the dehydration degree. In other words, the controller  300  determines the frequency of performing the draining step by referring to at least one of the laundry amount, the water amount and the dehydration degree.  
      A time of performing the draining step S 600  is determined by at least one of three factors such as the laundry amount, the water amount and the dehydration degree. In other words, the controller  300  determines the performing time of the draining step S 600  by referring to at least one of the laundry amount, the water amount and the dehydration degree.  
      At the draining step S 600 , the rotation speed of the drum  130  is determined by at least one of three factors such as the laundry amount, the water amount and the dehydration degree. In other words, the controller  300  determines the rotation speed of the drum  130  by referring to at least one of the laundry amount, the water amount and the dehydration degree.  
      At the draining step S 600 , one of a performing frequency, a performing time and a rotation speed of the drum  130  is determined by one of the laundry amount, the water amount and the dehydration degree. In other words, in consideration of at least one of two factors such as the amount of the laundry and the degree of dehydration, the controller  300  determines the rotation frequency, the performing time, and the rotation speed of the drum  130  rotated at a low speed.  
      Meanwhile, the controller  300  may determine the frequency, a performing time and a rotation speed of the draining step by considering other factors except the laundry amount and the dehydration degree. In this case, other factors may be the size of the drum  130 , the capacity of the washing machine  100 , and the kind of the laundry.  
      Otherwise, at the draining step S 600 , at least one of N, a time for performing each the third speed rotation and the third speed is determined based on a weight of laundry. In this case, the controller  300  determines at least one of N, a time for performing each the third speed rotation and the third speed of the drum  130  by referring to the weight of laundry. In here, the weight of laundry is a weight in an early stage of the step S 500  of rotating the drum  130  at the second speed.  
      Otherwise, at the draining step S 600 , at least one of N, a time for performing each third speed rotation and the third speed is determined based on a change in weight of the laundry. In this case, the controller  300  determines at least one of N, a time for performing each the third speed rotation and the third speed of the drum  130  by referring to the change in weight of the laundry. In here, the change in weight of the laundry is difference between a weight in an early stage of the step S 500  of rotating the drum  130  at the second speed and a weight after the step S 600  of rotating the drum  130  at a third speed.  
      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 inventions. 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.