Patent Publication Number: US-7707672-B2

Title: Method for controlling driving of drum-type washing machine and apparatus thereof

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application is a Divisional of co-pending application Ser. No. 10/752,003, filed on Jan. 7, 2004, the entire contents of which are hereby incorporated by reference and for which priority is claimed under 35 U.S.C. §120. This application also claims priority under 35 U.S.C. §119(a) on Korean Patent Application No. 10-2003-0003028 filed in Republic of Korea on Jan. 16, 2003, the entire contents of 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 method for controlling a driving of a drum-type washing machine and an apparatus thereof. 
   2. Description of the Conventional Art 
   Generally, a washing machine is a mechanical apparatus for washing laundry by performing a washing process, a rinse process, and a dewatering process. The washing machine is divided into a pulsator method, an agitation method, a drum method, and etc. according to a washing method. Hereinafter, a general drum type washing machine will be explained with reference to  FIG. 1 . 
     FIG. 1  is a sectional view showing a construction of a drum type washing machine in accordance with the conventional art. 
   As shown, the drum type washing machine comprises a casing  12 , a tub  17  arranged in the casing  12 , and a drum  15  rotatably arranged in the tub  17 . 
   Hereinafter, a construction of the drum type washing machine according to the conventional art will be explained in more detail. 
   The casing  12  has a rectangular parallelepiped shape, and an aperture  22  through which laundry is put in/out is formed at a front side of the casing  12 . A door  23  for opening and closing the aperture  22  is disposed at a lateral surface of the aperture  22 . The tub  17  for accommodating washing water is installed in the casing  12 , and a supporting spring  11  and a damper  18  for shock-absorbingly supporting the tub  17  are respectively installed at upper and lower sides of the tub  17 . 
   A spider  13  for rotatably supporting the drum  15  is coupled to a rear side of the tub  17 , and a drum driving motor  14  for rotating the drum  15  is integrally coupled to a rear lateral surface of the spider  13 . 
   A water supply pipe and a water supply valve (not shown) for supplying washing water into the tub  17  are installed at an upper portion of the tub  17 , and a drain pump  19  for draining washing water through a drain pipe  16  is installed at a lower portion of the tub  17 . 
   A cyclic water pipe  20  for taking out washing water inside the tub  17  and circulating the taken washing water into the upper portion of the tub  17  is installed at one side of the drain pipe  16 , and a circulation pump  21  for pumping washing water is installed at the cyclic water pipe  20 . 
   According to this, when laundry is received in the drum  15  and detergent and washing water are supplied thereto, a control unit (not shown) controls the drum driving motor  14  thus to rotate the drum  15  and drives the circulation pump  21  thus to circulate washing water. 
   Then, when the washing process is completed, the control unit controls the drain pump  19  and the drum driving motor  14  thus to perform a drain process and a dewatering process in turn and supplies washing water into the tub  17  thus to perform a rinse process several times. Herein, the rinse process is performed several times, and whenever the rinse process is performed one time, the drain process and the dewatering process are also performed one time. 
   When the dewatering process is performed in a state that laundry is arranged with eccentricity in the drum  15 , the drum  15 , the tub  17 , and a supporting component for the drum  15  (not shown) are damaged and forcibly abraded. Accordingly, in order to prevent the damage and forcible abrasion, an amount of eccentricity of the drum  15  has to be detected before the dewatering process and when the amount of eccentricity is less than a preset reference value, the dewatering process has to be performed. 
   However, in the conventional drum type washing machine, when the dewatering process is completed after the washing process, or when the dewatering process is completed after the rinse process, a rotation speed of the drum is gradually decreased and the drum is stopped. According to this, vibration and noise are generated at a speed section where vibration of the drum  15  is drastically increased (for example, 150˜200 rpm (revolution per minute)). 
   Also, in the conventional drum type washing machine, an amount of eccentricity of the drum  15  is detected in a state that the drum  15  is rotated with a speed which is a little increased than a rotation speed of the drum  15  at the time of a washing process after the drum  15  is completely stopped after the washing process is performed, so that vibration and noise are generated at a speed section where vibration of the drum  15  is drastically increased (for example, 150˜200 rpm (revolution per minute)). 
   Besides, in the conventional drum type washing machine, when the detected amount of eccentricity exceeds the preset reference value (a reference value of an amount of eccentricity of the drum), the drum  15  is stopped and then is driven again, which is repeatedly performed several times or a dozen times According to this, it takes a lot of time to detect an amount of eccentricity of the drum  15  and then to proceed to a next step by making the amount of eccentricity be less than the preset reference value. 
   Besides, in the drum type washing machine according to the conventional art, an amount of eccentricity of the drum  15  is detected at a low speed and when the detected amount of eccentricity is less than the preset reference value, a rotational speed of the drum  15  is increased. According to this, the amount of eccentricity of the drum is again increased thus to cause vibration and noise. 
   In addition, in the drum type washing machine according to the conventional art, the time taken to rinse laundry with washing water is less than the time taken to supply washing water in order to rinse laundry, so that much washing water is put into the tub  17  and time for performing the rinse process is increased. 
   Minute explanations for the drum type washing machine according to the conventional art are also disclosed in U.S. Pat. Nos. 6,615,619 and 6,612,138. 
   SUMMARY OF THE INVENTION 
   Therefore, an object of the present invention is to provide a method for controlling a driving of a drum type washing machine capable of preventing vibration and noise and an apparatus thereof. 
   Another object of the present invention is to provide a method for controlling a driving of a drum type washing machine capable of reducing a usage of washing water and an apparatus thereof. 
   To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a method for controlling a driving of a drum type washing machine comprising the steps of rotating a drum with a preset speed faster than a speed that vibration of the drum is excessively generated accordingly as a rotation speed of the drum is decreased when a dewatering process of laundry is completed; and maintaining the preset speed and supplying washing water into the drum type washing machine. 
   In the method for controlling a driving of a drum type washing machine according to the present invention, a rinse process is performed in a state that a rotation speed of the drum is maintained as a preset speed. 
   To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is also provided an apparatus for controlling a driving of a drum type washing machine comprising: a drum driving motor for rotating a drum of a drum type washing machine; a water supply valve for supplying washing water into the drum type washing machine; and a control unit for rotating the drum through the drum driving motor with a preset speed faster than a speed that vibration of the drum is excessively generated accordingly as a rotation speed of the drum is decreased when a dewatering process of laundry is completed. 
   Herein, the control unit maintains a rotation speed of the drum as a preset speed and supplies washing water into the drum type washing machine through the water supply valve. 
   To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an apparatus for controlling a driving of a drum type washing machine comprising: a drum driving motor for rotating a drum of a drum type washing machine; a water supply valve for opening and closing a water supply pipe which supplies washing water into a tub of the drum type washing machine; and a control unit for rotating the drum through the drum driving motor with a preset equilibrium speed faster than a speed that vibration of the drum is excessively generated accordingly as a rotation speed of the drum is decreased when a dewatering process after a washing process is completed or when a dewatering process after a rinse process is completed, the control unit for simultaneously supplying washing water for a rinse process into the tub through the water supply valve. 
   To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is also provided a method for controlling a driving of a drum type washing machine comprising the steps of: rotating a drum with a preset equilibrium speed faster than a speed that vibration of the drum is excessively generated accordingly as a rotation speed of the drum is decreased when a dewatering process after a washing process is completed or when a dewatering process after a rinse process is completed; and rotating the drum with the preset equilibrium speed and supplying washing water for a rinse process into a tub of the drum type washing machine. 
   The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 

   
     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 specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
     In the drawings: 
       FIG. 1  is a sectional view showing a construction of a drum type washing machine in accordance with the conventional art; 
       FIG. 2  is a block diagram showing a construction of an apparatus for controlling a driving of a drum type washing machine according to one embodiment of the present invention; and 
       FIGS. 3A-3B  are a flow chart showing a method for controlling a driving of a drum type washing machine according to one embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
   Hereinafter, an apparatus for controlling a driving of a drum type washing machine capable of preventing vibration and noise of a drum, reducing a usage of washing water, and reducing a rinse time by rotating the drum with a preset equilibrium speed (200˜500 rpm) faster than a speed (150˜200 rpm) that vibration of the drum is excessively generated accordingly as a rotation speed of the drum is decreased when a dewatering process of laundry is completed, by maintaining the drum as the equilibrium speed, and by supplying washing water into the drum type washing machine, and a method thereof will be explained with reference to  FIGS. 2 and 3B . Herein, the reference numerals of  FIG. 1  will be given to the present invention having the same construction as the conventional art. 
     FIG. 2  is a block diagram showing a construction of the apparatus for controlling a driving of the drum type washing machine according to one embodiment of the present invention. 
   As shown, the apparatus for controlling a driving of a drum type washing machine according to the present invention comprises a drum driving motor  105  for rotating a drum  15  of a drum type washing machine; a water supply valve  106  for opening and closing a water supply valve which supplies washing water into a tub  17  of the drum type washing machine; a drain pump  107  for draining washing water through a drain pipe  16  of the drum type washing machine; a circulation pump  108  for pumping washing water taken out from inside of the tub  17  in order to circulate through a cyclic water pipe  20  of the drum type washing machine; an eccentric amount detecting unit  102  for detecting an amount of eccentricity of the drum  15 ; a timer  103  for calculating a rinse time; a water level sensor  101  for detecting a level of water supplied into the tub  17 ; and a control unit  104  for rotating the drum  15  through the drum driving motor  105  with a preset equilibrium speed faster than a speed that vibration of the drum is excessively generated accordingly as a rotation speed of the drum is decreased when a dewatering process is completed, for maintaining the preset equilibrium speed, and for supplying washing water into the tub  17  through the water supply valve  106  in order to efficiently perform a drain process, a rinse process, and a dewatering process without vibration and noise. 
   Hereinafter, the method for controlling a driving of the drum type washing machine will be explained with reference to  FIGS. 3A-3B  in more detail. 
     FIGS. 3A-3B  are a flow chart showing the method for controlling a driving of the drum type washing machine according to one embodiment of the present invention. 
   When laundry to be washed is received into the drum  15 , the control unit  104  controls the water supply valve  106  so as to supply washing water into the tub  17 . At this time, the control unit  104  controls the drum driving motor  14  so that the drum  15  can be clockwise or counterclockwise rotated with a preset rotation speed (for example, 50 rpm), thereby performing a washing process (S 31 ). 
   When said washing process is completed, the drum driving motor  14  rotates the drum  15  with a first rotation speed (for example, 100 rpm) increased than the original rotation speed at the time of performing the washing process according to a control signal of the control unit  10 . At this time, the eccentric amount detecting unit  102  detects a first eccentric amount of the drum  15  at the first rotation speed on the basis of the control signal of the control unit  104  (S 32 ). The eccentric amount detecting unit  102  can detect the eccentric amount by comparing a duty value at the time when the drum  15  is rotated, and the method for detecting the eccentric amount is the same as the conventional one thus to omit its explanations. 
   When the detected first eccentric amount of the drum  15  is the same as the preset first reference value or exceeds (S 33 ), a driving of the drum  15  is stopped (S 34 ), then the drum  15  is rotated with the first speed (S 35 ), and then the process for detecting the first eccentric amount (S 32 ) is repeatedly performed. That is, the process for driving and stopping the drum  15  is repeatedly performed so that the detected first eccentric amount can be less than the preset first reference value. Herein, the preset reference value means a preset reference eccentric amount, and the reference eccentric amount is preferably about 400 g. 
   Then, when the detected eccentric amount of the drum  15  is less than the preset reference value (S 33 ), the control unit  104  increases the rotation speed of the drum  15  to a second speed (for example, more than 400 rpm). At this time, the eccentric amount detecting unit  102  detects a second eccentric amount of the drum  15  on the basis of a control signal of the control unit  104  (S 36 ). That is, the control unit  104  rotates the drum  15  until the detected second eccentric amount becomes less than the preset reference value and stops, which is repeatedly performed. Then, when the detected second eccentric amount is less than the preset reference value, the control unit  104  increases the rotation speed of the drum  15  thus to perform a dewatering process (S 37 ). 
   When the dewatering process (S 37 ) is completed, the drum  15  is not stopped but the rotation speed of the drum is maintained as the first speed (for example, 100 rpm). That is, the first eccentric amount is again detected at the first speed. 
   When the dewatering process is completed and the detected first eccentric amount exceeds the preset reference value (S 38 ), the control unit  104  respectively controls the drum driving motor  14  and the water supply valve  106  thus to stop the drum  15  (S 39 ), performs a water supply process (S 40 ), and then performs a rinse process (S 41 ). Herein, the rinse process is performed several times, and whenever the rinse process is performed one time, a drain process and a dewatering process are also performed one time. Also, the dewatering process is performed one time after a washing process is completed. 
   Subsequently, when the rinse process (S 41 ) is completed, the control unit  104  rotates the drum  15  with the first rotation speed thus to detect the first eccentric amount (S 32 ), and detects a second eccentric amount (S 36 ), in which a series of processes (S 32 ˜S 41 ) are repeatedly performed. 
   Meanwhile, when the first eccentric amount of the drum  15  is less than the preset reference value (S 38 ), the control unit  104  maintains the rotation speed of the drum  15  as an equilibrium speed faster than a speed that vibration of the drum is excessively generated, and supplies washing water into the tub  17 . For example, when the detected second eccentric amount of the drum  15  is less than the preset reference value (S 38 ), the drum driving motor  14  rotates the drum  15  with 250 rpm (equilibrium speed) on the basis of a control signal of the control unit  104  (S 42 ). At this time, the water supply valve  106  supplies washing water into the tub  17  on the basis of a control signal of the control unit  104  while the drum  15  is rotated with 250 rpm (equilibrium speed) (S 43 ). Herein, the preset equilibrium speed is preferably 250 rpm. 
   Then, the timer  103  counts a rinse time on the basis of the control signal of the control unit  104  (S 44 ), and the water level sensor  101  detects a level of water supplied into the tub  17  on the basis of a control signal of the control unit  104  (S 45 ). 
   When the level of washing water supplied into the tub  17  becomes a preset water level (for example, a water level enough to touch a lower portion of the drum  15 ) (S 46 ), the control unit  104  controls the circulation pump  21  thus to circulate washing water inside the tub  17  (S 47 ). Herein, the control unit  104  continuously supplies washing water in order to prevent a water level from being lowered accordingly as laundry comes into contact with washing water and thereby laundry absorbs washing water. 
   Whenever a preset time (for example, 30 seconds˜60 seconds) lapses, the control unit  104  controls the water level sensor  101  thus to detect a water level (S 48 ), and when the detected water level reaches a preset water level (S 49 ), the control unit  104  controls the water supply valve  106  thus to stop a water supply process (S 50 ). 
   Next, the control unit  104  calculates a rinse time counted by the timer  103  (S 51 ), and controls the drain pump  19  when the calculated rinse time lapses a preset time (for example, 20 minutes) (S 52 ) thus to perform a drain process (S 53 ). Herein, the control unit  104  controls the drain pump thus to perform a drain process through the drain pipe while the drum is rotated with the preset equilibrium speed. 
   When the drain process is completed, the control unit  104  counts the number of times of the rinse process (S 54 ), and when the counted number of times of the rinse process is less than a preset number of times of a rinse process (for example, three times) (S 55 ), the control unit  104  increases the equilibrium speed (250 rpm) of the drum  15  into a dewatering speed (for example, 600˜1800 rpm) thus to perform a dewatering process (S 58 ). Then, the control unit  104  returns to the step for rotating the drum  15  with 250 rpm (equilibrium speed) (S 42 ). That is, when the dewatering process is completed (S 58 ), the control unit  104  controls the drum driving motor  14  thus to make the drum  15  maintain the preset equilibrium speed (S 42 ) and supplies washing water into the tub  17  (S 43 ) thus to repeatedly perform the rinse processes (S 42 ˜S 55 ). 
   On the contrary, when the counted number of times of the rinse process is the same as the preset number of times of a rinse process (S 55 ), the control unit  104  performs a dewatering process (S 56 ) and stops the drum  15  when the dewatering process is completed (S 57 ). 
   As aforementioned, in the present invention, when a dewatering process is completed after a washing process or a dewatering process is completed after a rinse process, washing water is supplied at a preset equilibrium speed faster than a speed that vibration of the drum is excessively generated accordingly as a rotation speed of the drum is decreased, thereby performing a rinse process Therefore, vibration and noise generated by the drum at the time of stopping the drum can be reduced, and time interval between the rinse process and the dewatering process can be reduced. 
   Besides, in the present invention, the rinse process is performed in a state that the drum is maintained as a preset equilibrium speed properly reduced from a dewatering speed, thereby greatly reducing rinse time. 
   In addition, in the present invention, a water supply process is performed without stopping the drum and a rinse process is performed by maintaining a water level enough to circulate washing water, thereby greatly reducing an amount of washing water and enhancing a rinse speed. 
   Besides, in the present invention, before a dewatering process before the first rinse process, an amount of eccentricity of the drum is detected at the second speed (400 rpm) faster than a rotation speed of the drum at the time of a washing process and slower than a rotation speed of the drum at the time of a dewatering process, thereby preventing vibration and noise generated at a speed section between the time of detection of the amount of eccentricity and the time of a dewatering process. According to this, damage and forcible abrasion of the drum, the tub, and the rotation supporting component of the drum due to the amount of eccentricity can be reduced and the drum type washing machine can be stably driven, thereby prolonging a lifespan of the drum type washing machine. 
   As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.