Patent Publication Number: US-2007101773-A1

Title: Drum washing machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of Korean Patent Application No. 2005-0106531, filed Nov. 8, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a drum washing machine, and more particularly, to a drum washing machine having a steam generating device for spraying steam of a high temperature to a rotary drum to improve sterilizing and washing capabilities.  
      2. Description of the Related Art  
      Generally, a drum washing machine sequentially performs washing, rinsing, and dehydrating operations by the rotation of a drum, which is rotatably installed in a horizontal tub using driving force of a motor under the condition that detergent, water, and laundry are placed into the drum, thereby washing the laundry in the drum.  
      Recently, various supplementary functions designed to satisfy user&#39;s tastes besides a particular washing function have been added to the drum washing machine. For example, Korean Patent Application No. 2003-0015003 discloses a drum washing machine having a hot air generating device, which blows hot air into a tub so as to rapidly dry laundry. Further, Korean Utility Model Registration No. 20-0397085 discloses a drum washing machine having a steam generating device, which sprays hot steam into a rotary drum so as to improve sterilizing and washing capabilities.  
      Since the above steam generating device generates steam by heating tap water, when the steam generating device is used over a long period of time, scale accumulates in the steam generating device due to hard water components, such as magnesium ions (Mg++) or calcium ions (Ca++). The scale gradually builds up in a water channel of the steam generating device, thereby causing an increase in flow resistance, and, in the worst case, causing the channel to be closed.  
     SUMMARY OF THE INVENTION  
      Therefore, one aspect of the invention is to provide a drum washing machine having a scale eliminating unit for efficiently eliminating scale deposited in a steam generating device.  
      In accordance with one aspect, the present invention provides a drum washing machine including: a housing; a tub for containing washing water; a drum rotatably installed in the tub; and a steam generating device installed in the housing for supplying steam for sterilizing laundry to the drum, wherein a scale eliminating unit including at least one protrusion formed on the inner circumferential surface of a water supply channel of the steam generating device is installed in the water supply channel.  
      In accordance with another aspect, the present invention provides a drum washing machine including: a housing; a tub for containing washing water; a drum rotatably installed in the tub; and a steam generating device installed in the housing for supplying steam for sterilizing laundry to the drum, wherein a water supply channel of the steam generating device branches into a first channel for supplying water to the steam generating device in a washing operation and a second channel for supplying water to the steam generating device in a rinsing operation, and a scale eliminating unit including a water supply valve and a pulsation circuit for controlling the flow rate and amount of the water is installed in the second channel.  
      In accordance with yet another aspect, the present invention provides a drum washing machine including: a housing; a tub for containing washing water; a drum rotatably installed in the tub; and a steam generating device installed in the housing for supplying steam for sterilizing laundry to the drum, wherein a scale eliminating unit is installed in a water supply channel of the steam generating device, and includes a water supply valve and a pulsation circuit for controlling the flow rate and amount of supplied water.  
      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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which:  
       FIG. 1  is a perspective view of a drum washing machine of the present invention;  
       FIG. 2  is a longitudinal sectional view of the drum washing machine of the present invention;  
       FIG. 3  is a sectional view of a scale eliminating unit of a steam generating device of a drum washing machine in accordance with one embodiment of the present invention;  
       FIG. 4  is a sectional view of a scale eliminating unit of a steam generating device of a drum washing machine in accordance with another embodiment of the present invention; and  
       FIG. 5  is a sectional view of a scale eliminating unit of a steam generating device of a drum washing machine in accordance with yet another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Reference will now be made in detail to the embodiment of the present 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 present invention by referring to the annexed drawings.  
       FIGS. 1 and 2  are perspective and longitudinal sectional views of a drum washing machine of the present invention.  
      With reference to  FIGS. 1 and 2 , the drum washing machine of the present invention includes a housing  10  forming the external appearance of the washing machine, a cylindrical tub  11  installed in the housing  10  for containing washing water, and a cylindrical drum  12  rotatably installed in the tub  11 .  
      Openings are respectively formed through the front surfaces of the tub  11  and the drum  12  so that a user can put laundry into and take the laundry out of the washing machine therethrough. A door  13  is hinged to one side of the front surface of the housing  10  such that the door  13  can open and close the openings of the tub  11  and the drum  12 .  
      A water supply device  14  for supplying the washing water and a detergent supply device  11   b  for mixing a detergent with the supplied washing water are installed above the tub  11 . The water supply device  14  includes a plurality of valves connected to an external water supply source for selectively controlling the supply of the washing water to the detergent supply device  11   b , a nano silver generator  38 , and a steam generating device  30 .  
      A drain pipe  15  and a drain pump  16  for discharging the washing water to the outside and a suspension device  17  for absorbing vibration generated from the rotation of the drum  12  are installed below the tub  11 .  
      The drum  12  is rotated by rotary force generated from a driving motor  18  installed in the lower portion of the inside of the housing  10 , and through holes  12   a  for passing the washing water stored in the tub  11  are formed through the outer circumferential surface of the drum  12 . A plurality of lifters  12   b  are installed on the inner surface of the drum  12 , thereby lifting and then dropping the laundry by the rotation of the drum  12  so that the laundry is washed.  
      A hot air supply device  20  for supplying hot air to rapidly dry the laundry after a washing operation is installed in the upper portion of the inside of the housing  10 .  
      As shown in  FIG. 2 , the hot air supply device  20  includes a motor  21  for generating driving force, a fan  23  connected to the motor  21  by a belt  22  ( FIG. 1 ) and rotated, a drying duct  24  for guiding air, supplied by the rotary force of the fan  23 , to the tub  11 , and a heater  25  installed in the drying duct  24  for heating the air, supplied by the rotary force of the fan  23 . Since the drying duct  24  is connected to the upper portion of the front surface of the tub  11 , the hot air heated by the heater  25  is supplied to the tub  11 , thereby rapidly drying the laundry under the condition that the laundry is rotated.  
      The steam generating device  30  for spraying steam to improve sterilizing and washing capacities of the drum washing machine is installed in the upper portion of the inside of the housing  10 . The steam generating device  30  is installed on a support plate  31 , crossing the central portion of the housing  10 , by a bracket  32  so that the steam generating device  30  is easily assembled with and disassembled from the housing  10 .  
      A direct water-type steam generating device, which causes the supplied water to be gradually introduced into an internal heater (not shown) for rapidly converting the water into steam, may be used as the steam generating device  30 . One end of the steam generating device  30  is connected to a water supply channel  33  so that water can be supplied from the water supply device  14  to the steam generating device  30 , and the other end of the steam generating device  30  is connected to the drying duct  24  of the hot air supply device  20  by a steam pipe  37  so that the generated steam can be supplied to the drum  12 .  
      In the drum washing machine of the present invention, a scale eliminating unit  40  for eliminating scale gradually deposited in the steam generating device  30  is installed in the water supply channel  33  for supplying water to the steam generating device  30 . FIGS.  3  to  5  respectively illustrate various scale eliminating units employed by the drum washing machine of the present invention, and a detailed description thereof will be described later.  
      The water supply channel  33  of the steam generating device  30 , in which the scale eliminating unit  40  is installed, branches into first and second channels  34  and  35 . The first channel  34  has sectional dimensions smaller than the sectional dimensions of the second channel  35 . The first channel  34  serves to supply water to the steam generating device  30  in a washing operation, and the second channel  35  serves to supply water the steam generating device  30  in a rinsing operation. The first and second channels  34  and  35  are interconnected by a coupler  36 , and is connected to the steam generating device  30 .  
      The scale eliminating unit  40  may be installed in the second channel  35 . The reason is that a small amount of water is required to generate steam and a large amount of water is required to eliminate scale.  
      Here, reference numeral  38  refers to a nano sliver generator, both ends of which are connected to the water supply device  14  and the tub  11  by separate water supply and discharge pipes, for supplying the washing water containing silver ions to the tub  11 , and reference. numeral  39  refers to a bypass channel serving as a safety device for preventing the internal pressure of the steam generating device  30  from rising greater than a designated value when the steam generating device  30  is closed. Identical to the steam generating device  30 , the nano silver generator  38  and the scale eliminating unit  40  are installed on the support plate  31  of the housing  10  so that the nano silver generator  38  and the scale eliminating unit  40  are easily attached to and detached from the housing  10 .  
       FIG. 3  illustrates a scale eliminating unit in accordance with one embodiment of the present invention. With reference to  FIG. 3 , the scale eliminating unit  40 , which is installed in the second channel  35 , as described above, includes at least one protrusion  42  protruded from the inner circumferential surface of the second channel  35 . The protrusion  42  may have one sectional shape selected from the group consisting of a circle, a triangle, a polygon, etc. Accordingly, when water passes through the second channel  35  with the protrusion  42 , the water collides with the protrusion  42  to generate turbulence. Thereby, it is possible to easily eliminate scale deposited in the steam generating device. The above protrusion  42  may be formed in the steam generating device  30 .  
       FIG. 4  illustrates a scale eliminating unit in accordance with another embodiment of the present invention. The scale eliminating unit  44  serves to vary the sectional dimensions of the second channel  35  in the longitudinal direction so that the supplied water generates larger turbulence. For example, as shown in  FIG. 4 , when the scale eliminating unit  44  decreases and then increases the sectional dimensions of the second channel  35  having one end connected to the water supply device and the other end connected to the tub, the flow rate of the water in the second channel  35  is varied, thereby generating larger turbulence. When at least one protrusion  42  is further formed in the second channel  35 , the water in the second channel  35  generates severer turbulence.  
       FIG. 5  illustrates a scale eliminating unit in accordance with yet another embodiment of the present invention. The scale eliminating unit of this embodiment includes a valve  46  installed at one end thereof, to which water is supplied. In order to eliminate scale deposited in the steam generating device  30 , the valve  46  is closed, and is then temporarily opened so that a large amount of water is supplied to the steam generating device  30 , thereby selectively controlling the flow rate and amount of the water introduced into the steam generating device  30 . Accordingly, it is possible to eliminate the scale deposited in the steam generating device  30 .  
      A pulsation circuit may be electrically connected to the valve  46 . The pulsation circuit periodically or non-periodically controls the supply of a pulse signal, and thus controls the opening and closing of the valve  46  and the opening degree of the valve  46 , thereby controlling the intermittent supply of the water introduced into the steam generating device  30  and efficiently eliminating the scale deposited in the steam generating device  30 .  
      Hereinafter, a scale-eliminating operation of a steam generating device of the above-mentioned drum washing machine of the present invention will be described.  
      As described above, the water supply channel  33  of the steam generating device  30  branches into two channels  34  and  35 . In the washing operation, water, which is introduced into the first channel  34  having a smaller radius, is converted into steam by the steam generating device  30 , and the steam is supplied to the drum  12  through the drying duct  24 .  
      In the rinsing operation after the washing operation, the water supply device  14  closes the first channel  34 , and opens the second channel  35 . Then, the scale eliminating unit  40  in the second channel  35  is operated to form turbulence or to supply water having varied flow rate and amount to the steam generating device  30 , thereby efficiently eliminating scale deposited in the steam generating device  30 .  
      As apparent from the above description, the present invention provides a drum washing machine having a steam generating device, which include a scale eliminating unit for generating turbulence of water or supplying water having varied flow rate and amount to the steam generating device, thereby efficiently eliminating scale, deposited in the steam generating device due to hard water components, such as magnesium ions (Mg++) or calcium ions (Ca++).  
      Although embodiments of the invention have been shown and described, it would be appreciated by those skilled in the art that 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.