Abstract:
A washing machine and washing control method thereof. The washing control method not only improves the effectiveness of a preliminary washing cycle that is an optional function of the washing machine, but also reduces the amount of detergent and wash water that is used for the preliminary washing cycle. For this, the washing control method includes determining whether or not a preliminary washing cycle is selected, supplying a lesser amount of wash water than a desired amount of wash water that is determined based on the amount of laundry if the preliminary washing cycle is selected, and performing the preliminary washing cycle, and supplying a certain amount of wash water additionally after completing the preliminary washing cycle, and performing a main washing cycle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Korean Patent Application No. 2006-0002066, filed on Jan. 8, 2006 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a washing machine and a washing control method thereof, and, more particularly, to a washing machine and a washing control method thereof, which can regulate the amount of detergent and wash water supplied during preliminary washing, achieving an improvement in wash performance. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, a washing machine, more particularly, a drum-type washing machine, is an appliance to wash laundry contained in a cylindrical rotary drum by repeatedly raising and dropping the laundry as the drum rotates. Although the drum-type washing machine has a long wash time, it tends to reduce damage to the laundry and reduce the amount of water used when compared to a conventional pulsator-type washing machine. Therefore, the demand for such a drum-type washing machine is increasing. Currently, a washing machine employs a variety of ways to improve a wash performance. One example of the variety of ways is to add a preliminary washing cycle to a basic washing process, such that the preliminary washing cycle is selectively performed if necessary. 
         [0006]    The preliminary washing cycle agitates the laundry before a main washing cycle in order to remove dust or dirt clinging to the laundry, which improves the efficacy of the main washing cycle. The preliminary washing cycle is followed by a spin-drying operation after it is performed for a predetermined time. The amount of detergent used in the preliminary washing cycle corresponds to 30% to 50% of the main washing cycle, however, the preliminary washing cycle uses the same amount of wash water as the main washing cycle. A motor agitation time of the preliminary washing cycle is set to 12% to 34% of the main washing cycle. 
         [0007]    In association with a conventional washing machine having both the preliminary and main washing cycles, if the preliminary washing cycle as stated above is selected, wash water for use in the preliminary washing cycle is supplied into a rotary drum by way of a preliminary washing detergent chamber that is defined in a detergent supply device. Then, the preliminary washing cycle is performed to wash the laundry in the drum using a force of gravity that results in the laundry falling as the drum rotates in accordance with a motor agitation, while allowing a detergent to be mixed well with the wash water. After completion of the preliminary washing cycle, a spin-drying operation is performed at approximately 400 to 600 rpm. After that, wash water is again supplied into the drum, to progress to the generally known main washing cycle. 
         [0008]    The conventionally performed preliminary washing cycle as stated above has been provided to improve a wash performance by approximately 3% to 5%. However, such an improvement in wash performance is a negligible level when considering the amount of detergent and wash water used, and a motor agitation time required to perform the preliminary washing cycle. Therefore, there exists a need to improve the preliminary washing cycle to reduce the amount of detergent and wash water used. 
       SUMMARY OF THE INVENTION 
       [0009]    Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention. 
         [0010]    The invention has been made in order to solve the above problems. It is an aspect of the invention to provide a washing machine and a washing control method thereof, wherein a preliminary washing cycle, which is an optional function of the washing machine, can be performed with a high efficiency while achieving a reduction in the amount of detergent and wash water that is used therefor. 
         [0011]    It is another aspect of the invention to provide a washing machine and a washing control method thereof, wherein the amount of detergent and wash water that is used for a preliminary washing cycle can be regulated, whereby a reduction in the amount of detergent and wash water can be accomplished while achieving an improvement in wash performance. 
         [0012]    It is yet another aspect of the invention to provide a washing machine and a washing control method thereof, which can reduce the amount of detergent used in a preliminary washing cycle without a reduction in wash performance. 
         [0013]    Consistent with one aspect, an exemplary embodiment of the invention provides a method for controlling a washing machine, including: determining whether or not a preliminary washing cycle is selected; supplying a lesser amount of wash water than a desired amount of wash water that is determined based on an amount of laundry if the preliminary washing cycle is selected and performing the preliminary washing cycle; supplying a certain amount of wash water additionally after completing the preliminary washing cycle based on a difference between a desired amount of wash water and the lesser amount of wash water supplied during the preliminary washing cycle; and performing a main washing cycle. 
         [0014]    The amount of wash water, supplied during the preliminary washing cycle, may be approximately 70% of the desired amount of wash water. 
         [0015]    The main washing cycle may be performed as the wash water is additionally supplied to top up the desired amount without draining the used wash water after the preliminary washing cycle. 
         [0016]    The certain amount of wash water, additionally supplied during the main washing cycle, may be obtained by subtracting the amount of wash water supplied during the preliminary washing cycle from the desired amount of wash water. 
         [0017]    Consistent with another aspect, an exemplary embodiment of the invention provides a washing machine having a motor and a water supply device, including: a signal input unit to select a preliminary washing cycle; and a controller to control the water supply device if the preliminary washing cycle is selected, so as to reduce the amount of wash water, to be supplied during the preliminary washing cycle, below a desired amount of wash water that is determined based on the amount of laundry. 
         [0018]    The controller may control the water supply device during the preliminary washing cycle in such a manner that a lesser amount of wash water than the desired amount of wash water, which is determined based on the amount of laundry, is supplied to perform the preliminary washing cycle, and a certain amount of wash water is supplied additionally after completing the preliminary washing cycle without draining the used wash water. 
         [0019]    The controller may set the amount of wash water, to be supplied during the preliminary washing cycle, to approximately 70% of the desired amount of wash water. 
         [0020]    Additionally, the controller may advance the main washing cycle after supplying the certain amount of wash water. 
         [0021]    The controller may set the certain amount of wash water, to be supplied additionally during the main washing cycle, to approximately 30% of the desired amount of wash water. 
         [0022]    Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    These and/or other aspects and advantages of the exemplary embodiments of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, of which: 
           [0024]      FIG. 1  is a sectional view showing the configuration of a washing machine consistent with the invention; 
           [0025]      FIG. 2  is a control block diagram showing a washing control mechanism of the washing machine consistent with an exemplary embodiment of the invention; and 
           [0026]      FIG. 3  is a flow chart showing the sequential operation of a method for improving the effectiveness of preliminary washing in association with the washing machine consistent with the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    Reference will now be made in detail to an exemplary embodiment of the invention, an example of which is illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiment is described below to explain the invention by referring to the figures. 
         [0028]      FIG. 1  is a sectional view showing the configuration of a washing machine consistent with the invention. 
         [0029]    As shown in  FIG. 1 , the washing machine consistent with the invention includes a drum-shaped water tub  11  received in a body  10  to contain wash water therein, and a rotary drum  12  rotatably received in the water tub  11 . 
         [0030]    The water tub  11  is generally tilted relative to a washing machine mounting plane by a predetermined inclination α so that a front wall  11   a  thereof, formed with a laundry entrance opening  11   b,  is positioned higher than a rear wall  11   c  thereof. In the same manner as the water tub  11 , the rotary drum  12 , received in the water tub  11 , is tilted so that a front wall  12   a  thereof, formed with a laundry entrance opening  12   b,  is positioned higher than a rear wall  12   c  thereof. 
         [0031]    Specifically, the rotary drum  12  is mounted so that a rotating center axis “A” thereof is tilted relative to the washing machine mounting plane by the predetermined inclination α to thereby allow the front wall  12   a,  formed with the opening  12   b,  to face up and to the front. In this case, a rotary shaft  13 , which is coupled to the center of the rear wall  12   c  of the rotary drum  12 , is penetrated through and supported by the center of the rear wall  11   c  of the water tub  11 . Accordingly, the rotary drum  12  is rotatable in the water tub  11  about the rotary shaft  13 . 
         [0032]    A plurality of holes  12   d  are perforated through a circumferential wall of the rotary drum  12 , and a plurality of lifters  14  are arranged along an inner wall surface of the rotary drum  12  to raise and drop laundry contained in the drum  12  as the rotary drum  12  rotates. A motor  15  is mounted at an outer surface of the rear wall  11   c  of the water tub  11  to rotate the rotary shaft  13  connected to the rotary drum  12 . Accordingly, when the motor  15  is driven, the washing, rinsing and spin-drying operations of the washing machine can be performed. Also, a heater  16  is mounted in a bottom region of the water tub  11  to heat wash water supplied into the water tub  11 . 
         [0033]    The motor  15  includes a stator  15   a  fixed to the rear wall  11   c  of the water tub  11 , a rotor  15   b  rotatably disposed around the stator  15   a,  and a rotary plate  15   c  to connect the rotor  15   b  to the rotary shaft  13 . 
         [0034]    The body  10  is formed, at a front wall thereof, with an opening  17   b  to correspond to the opening  12   b  of the rotary drum  12  and the opening  11   b  of the water tub  11 , so as to put laundry into the rotary drum  12  or to take the laundry out of the rotary tub  12 . A door  17  is mounted at the opening  17   b  to open or close the opening  17   b.    
         [0035]    A detergent supply device  18  and a water supply device  20  are mounted above the water tub  11 , and a drainage device  19  is mounted underneath the water tub  11  to drain wash water used from the water tub  11 . The drainage device  19  includes a drainage pipe  19   a,  a drainage valve  19   b,  and a drainage pump  19   c.    
         [0036]    The detergent supply device  18  is internally sectionalized into a plurality of chambers, and is positioned close to the front wall of the body  10  to facilitate the input of a detergent and rinse agent into the respective chambers. The plurality of sectionalized chambers include a preliminary washing detergent chamber to store a detergent for use in a preliminary washing cycle, a main washing detergent chamber to store a detergent for use in a main washing cycle, and a rinse agent chamber to store a rinse agent for use in a rinsing cycle. This arrangement is disclosed in Korean Patent Application No. 2003-0011317 filed by the applicant of the invention. Admittedly, any other known techniques may be employed to construct the above described arrangement. 
         [0037]    The water supply device  20  includes cold water and hot water supply pipes  21  and  22  to supply cold water and hot water, respectively, and water supply valves  23  and  24  mounted to the cold water and hot water supply pipes  21  and  22  to control the supply of cold water and hot water, respectively. 
         [0038]    The cold water and hot water supply pipes  21  and  22  are connected to the detergent supply device  18 , such that water, supplied from an exterior water source, can be supplied into the detergent supply device  18 . A separate water supply pipe  25  is mounted between the detergent supply device  18  and the water tub  11  to supply the water, having passed through the detergent supply device  18 , into the water tub  11 . The water supply pipe  25  is provided at an outlet thereof with a water supply nozzle  26 . With this arrangement, the water is adapted to pass through the detergent supply device  18  prior to being supplied into the water tub  11 , whereby the detergents inside the detergent supply device  18  can be supplied into the water tub  11  after being dissolved in the water. 
         [0039]      FIG. 2  is a control block diagram showing a washing control mechanism of the washing machine consistent with an exemplary embodiment of the invention. As shown in  FIG. 2 , the washing control mechanism includes a signal input unit  100 , a temperature sensor  110 , a water level sensor  120 , a controller  130 , a drive unit  140 , and a speed sensor  150 . 
         [0040]    The signal input unit  100  is used to input a variety of operational information, including a wash program, a temperature of wash water, revolutions per minute for a spin-drying cycle, and an additional rinsing cycle, which are selected based on the material of laundry, to the controller  130 . The signal input unit  100  is provided with a key for selecting the preliminary washing cycle, in which the amount of water supplied is regulated, before the main washing cycle in order to achieve an improvement in wash performance. 
         [0041]    The temperature sensor  110  is used to sense the temperature of wash water supplied into the water tub  11 . The water level sensor  120  is used to sense the level of wash water supplied into the water tub  11 . 
         [0042]    The controller  130  is a micro-computer to control the washing machine in accordance with the operational information inputted from the signal input unit  100 . If the preliminary washing cycle is selected, the controller  130  controls the operation of the water supply device  20  to reduce the amount of wash water used, in such a manner that 70% of the overall wash water is supplied during the preliminary washing cycle and the remaining wash water of 30% is supplied during the main washing cycle in a two-stage water supply control manner. 
         [0043]    As the wash water is supplied based on the selection of the preliminary washing cycle, the controller  130  controls the supply of detergent in accordance with a three-stage detergent supply method. In a first stage, 30% of a predetermined amount of detergent is supplied for the preliminary washing cycle, and 100% of the predetermined amount of detergent is supplied for the main washing cycle. In a second stage, 30% of the predetermined amount of detergent is supplied for the preliminary washing cycle, and 80% of the predetermined amount of detergent is supplied for the main washing cycle. In a third stage, 50% of the predetermined amount of detergent is supplied for the preliminary washing cycle, and 60% of the predetermined amount of detergent is supplied for the main washing cycle. This detergent supply method is proved to reduce the amount of detergent used by 15% as compared to an amount of detergent conventionally used, or to achieve an improvement in wash performance with the amount of detergent conventionally used. 
         [0044]    After completing the preliminary washing cycle, the controller  130  controls the operation of both the drainage device  19  and the water supply device  20 , such that the remaining wash water is 30% of the desired amount, except for the wash water used during the preliminary washing cycle, is supplied, along with the main washing detergent, in order to top up the wash water to 100% of the desired amount, while continuously maintaining the preliminary washing state without draining or dehydrating the wash water. 
         [0045]    The drive unit  140  is adapted to drive the motor  15 , wash heater  16 , drainage valve  19   b,  drainage pump  19   c,  and water supply valves  23  and  24  based on drive control signals from the controller  130 . 
         [0046]    Now, the operational sequence and effects of a washing control method associated with the washing machine having the above-described configuration will be described. 
         [0047]      FIG. 3  is a flow chart showing the operational sequence of a method for improving the effectiveness of preliminary washing in association with the washing machine consistent with the invention. The washing control method of the invention proposes to regulate the amount of detergent and wash water used during both the preliminary washing cycle and the main washing cycle, in order to improve the efficiency of the preliminary washing cycle. For this, the preliminary washing cycle may be set to a default, or a separate optional key may be provided to selectively induce the preliminary washing cycle only when it is pushed by a user. 
         [0048]    If laundry is put into the rotary drum  12 , and a variety of operational information, including a wash course, a temperature of wash water, revolutions per minute for a spin-drying cycle, and addition of a rinsing operation, is manually selected based on the material of laundry, the selected operational information is inputted to the controller  130  via the signal input unit  100 . 
         [0049]    Accordingly, to advance washing and rinsing cycles based on the operational information inputted from the signal input unit  100 , the controller  130  first determines whether or not the preliminary washing cycle is selected (S 200 ). 
         [0050]    If the preliminary washing cycle is selected, the controller  130  switches on the water supply valves  23  and  24 , such that wash water is supplied into the detergent supply device  18  through the water supply pipes  21  and  22 . After passing through the detergent supply device  18 , the wash water is supplied into the water tub  11  through the water supply pipe  25  until the wash water reaches a preliminary washing water level (S 210 ). Here, the preliminary washing water level is 70% of the overall wash water that is determined in accordance with the amount of laundry. 
         [0051]    As the wash water for preliminary washing is supplied, a detergent, which is stored in the preliminary washing detergent chamber of the detergent supply device  18 , is supplied by 30% to 50% of the amount of detergent used for the main washing cycle in the same manner as a conventional detergent supply method. The reason why the preliminary washing detergent is supplied along with 70% of the overall wash water is to achieve a high density rough wash as compared to a conventionally performed preliminary washing cycle that supplies 100% of the overall wash water. 
         [0052]    After the wash water is supplied into the water tub  11  to the preliminary washing water level, the controller  130  drives the motor  15  based on a predetermined rpm and operation rate (on/off rate), to rotate the rotary drum  12 . As the rotary drum  12  rotates, the preliminary washing cycle is performed to wash laundry contained in the drum  12  using a force of gravity that results when the laundry falls when the drum rotates and while, allowing the preliminary washing detergent to be mixed well with the wash water (S 220 ). 
         [0053]    During the preliminary washing cycle, the controller  130  determines whether or not a predetermined preliminary washing time T has passed by timing an operation time of the preliminary washing cycle (S 230 ). If the predetermined preliminary washing time T has passed, the controller  130  stops operations of all units including the drainage device  19 , such that the preliminary washing state is continuously maintained without draining the wash water used. 
         [0054]    Generally, after being used, the wash water looks dirty and has a low bubble generation performance. Therefore, the used wash water is considered to have a poor wash performance. However, in accordance with an article entitled “The Principle of Detergent and Wash”, published in the  Journal of the Japanese Textile Consumption Science  in November 1965, it has been proved, as a result of qualitative and quantitative analyses of the wash water used once, that the wash water contains 90% of detergent active components and has a good wash ability, and therefore, is reusable for subsequent washing cycles. Accordingly, when the detergent used for the preliminary washing cycle is used again in the main washing cycle, it achieves 100% effectiveness of the desired washing ability if the new detergent is replenished by only 10% of the wash water. 
         [0055]    Accordingly, the controller  130  supplies the remaining wash water of 30% required for main washing, along with a detergent, after completing the preliminary washing cycle (S 240 ). 
         [0056]    As the wash water for main washing is supplied, a detergent, which is stored in the main washing detergent chamber of the detergent supply device  18 , is supplied in the same manner as a conventional detergent supply method, or optionally, in an amount of detergent that is 60% to 80% less than the amount of detergent used for main washing cycle. When the same amount of detergent as the conventional detergent supply method is used, for example, the amount of detergent for the preliminary washing cycle is reduced by 30% to 50% and the amount of detergent used in the main washing cycle detergent is unchanged, the reduction in the amount of detergent only for the preliminary washing cycle has the effect of improving the wash performance from 3% to 10%. Here, an improvement in wash performance by 10% can be achieved by a European model using a water temperature of 40□. 
         [0057]    In the invention, for example, the first amount of detergent of the conventional method is reduced by 15% when the amount of detergent for the preliminary washing cycle is reduced by 30% to 50% and the amount of detergent for the main washing cycle is reduced by 60% to 80% in a second amount of detergent. The washing effect of the second amount of detergent is the same as the conventional method. Thus, the results using the reduced second amount of detergent for the preliminary washing cycle and the main washing cycle are comparable to the conventional method using the first amount of detergent. 
         [0058]    If the remaining wash water is 30% and supplied into the water tub  11  during the main washing cycle to top up the wash water to 100% of the desired amount, the controller  130  drives the motor  15  based on a predetermined rpm and operation rate (on/off rate) to rotate the rotary drum  12 . As the rotary drum  12  rotates, the main washing cycle is performed to wash laundry contained in the drum  12  using a force of gravity that results when the laundry falls as the drum rotates, while allowing the main washing detergent to be mixed well with the wash water (S 250 ). 
         [0059]    After that, the remaining general cycles of the washing machine are successively performed (S 260 ), and then, the operation of the washing machine is finished. 
         [0060]    As apparent from the above description, the invention provides a washing machine and a washing control method thereof having the following effects. 
         [0061]    Firstly, according to the invention, it is possible to achieve not only an improvement in the efficiency of a preliminary washing cycle that is an optional function of the washing machine, but also a reduction in the amount of detergent and wash water for use in the preliminary washing cycle. 
         [0062]    Secondly, according to the invention, the amount of detergent and wash water used for the preliminary washing cycle can be regulated. This has the effect of achieving an improvement in wash performance by approximately 10% when the same amount of detergent as a conventional detergent supply method is used, and also reducing the amount of detergent to be used by 15% while achieving the same wash effect as the conventional method. As a result, the amount of wash water to be used can be reduced by up to 50%. 
         [0063]    Although an embodiment of the invention has been shown and described, it would be appreciated by those skilled in the art that the described embodiment is merely exemplary so as to realize a washing machine and a washing control method consistent with the invention, and therefore, various changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.