Patent Publication Number: US-6981395-B2

Title: Drum type washing machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of Korean Patent Application No. 2001-60366 filed on Sep. 28, 2001, in the Korean Industrial 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 washing machine, and more particularly, to a drum type washing machine having a water circulation device which pumps wash water contained in a fixed drum to feed the wash water to a rotary drum, so as to enhance the washing effect. 
   2. Description of the Related Art 
   Generally, a drum type washing machine is an appliance designed to wash laundry by dropping the laundry from a top to a bottom inside of a rotary drum as the rotary drum is rotated. Such a drum type washing machine includes a fixed drum, a rotary drum and shock absorbing members. The fixed drum is suspended in a box-shaped cabinet which defines an outer appearance of the washing machine, and contains wash water therein. The rotary drum is set in the fixed drum so as to be rotatable in alternating directions. The shock absorbing members support the fixed drum in the box-shaped cabinet. 
   In conventional drum type washing machines, washing, rinsing, and spin-drying operations are automatically carried out according to a previously input program, while a rotary drum is rotated. In this case, washing courses are classified into a heavy course, a normal course, a wool course, etc., according to a kind and state of laundry to be washed. However, the conventional drum type washing machines are limited in their washing efficiency, because the washing and rinsing operations are achieved only by dropping of the laundry through the rotation of the rotary drum. 
   To overcome this problem, Korean U.M. Application No. 1997-11762/Laid-Open Publication No. 1998-67224 discloses a wash water circulation device for drum type washing machines. The wash water circulation device forcibly pumps wash water in a fixed drum and sprays the wash water into a rotary drum containing laundry therein. 
     FIG. 1  shows that the wash water circulation device disclosed above includes a spray nozzle  3  which sprays the wash water pumped from the bottom to the top inside of a tub (the fixed drum)  2  by a drain pump  1 , a first solenoid valve  4  which is installed at a position adjacent to the spray nozzle  3  and closes during a drain operation and opens during a washing operation, a water circulation hose  6  having one end connected to the spray nozzle  3  and the other end connected to a T-shaped connector  7  positioned between the drain pump  1  and a drain hose  5 , and a second solenoid valve  8  which is installed at an inlet of the drain hose  5  and closes during the washing operation. 
   The spray nozzle  3  is positioned on top of the tub  2 , so as to have the wash water sprayed from the spray nozzle  3  to flow into a drum (the rotary drum)  9  through a plurality of spin-drying perforations  9   a  formed on a wall of the drum  9 . The second solenoid valve  8  prevents the wash water pumped by the drain pump  1  from being drained through the drain hose  5  during the washing operation. 
   Thus, where the drain pump  1  is activated during the washing operation, which is carried out by rotation of the drum  9 , the wash water in the tub  2  is pumped to the top of the tub  2  and then sprayed downward therefrom. That is, the wash water pumped by the drain pump  1  is guided to the spray nozzle  3  through the water circulation hose  6  and then sprayed from the spray nozzle  3  to the drum  9  to flow into the drum  9  through the perforations  9   a , so as to improve the washing efficiency and solubility of detergent. 
   However, since the wash water sprayed from the spray nozzle  3  is first sprayed against an external wall of the drum  9 , only a small portion of the sprayed wash water flows into the drum  9  through the perforations  9   a . The remaining wash water flows down along the external wall of the drum  9  and is collected in the bottom of the tub  2 . 
   Therefore, although the solubility of the detergent can be improved by circulation of the wash water, the sprayed wash water achieves limited improvement in washing the laundry. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention is to provide a drum type washing machine with an improved water circulation device, which sprays wash water directly into a rotary drum containing laundry therein during a washing operation. Accordingly, a washing efficiency of the laundry and solubility of detergent are enhanced. 
   Additional objects and 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. 
   To achieve the above and other objects of the present invention, there is provided a drum type washing machine comprising a cabinet which defines an outer appearance of the washing machine, a fixed drum set in the cabinet to contain wash water therein, a rotary drum rotatably set inside the fixed drum, a pump unit which pumps out the wash water contained in the fixed drum, a water circulation device which feeds the wash water pumped out by the pump unit into the rotary drum, wherein the water circulation device comprises a storing unit which defines a space to temporarily hold the wash water pumped out by the pump unit, guides the wash water to a rear panel of the rotary drum, and is provided between a rear panel of the fixed drum and the rear panel of the rotary drum, and a spraying unit which is provided at the rear panel of the rotary drum and sprays the wash water contained in the storing unit into the rotary drum. 
   The water circulation device further comprises a duct which is provided on an outer surface of the rear panel of the fixed drum, communicates with the storing unit, and includes a connecting port connected to an outlet of the pump. 
   The drum type washing machine further comprises a shaft-flange which is mounted to the rear panel of the rotary drum, and includes a center portion which receives a rotating shaft of the washing machine, wherein the storing unit includes a first projecting member having a ring shape and provided at a center portion of the rear panel of the fixed drum so as to be projected toward the rotary drum, a second projecting member which is provided at the shaft-flange so as to be projected toward the rear panel of the fixed drum and surrounds the first projecting member to form the space, and a sealing unit which seals a gap between the first and second projecting members. 
   The sealing unit comprises a friction ring arranged between an outer circumference of the first projecting member and an inner circumference of the second projecting member, and a retainer having a ring shape which holds the friction ring, wherein an outer edge of the retainer is inserted into the friction ring and an inner edge of the retainer is mounted to the first projecting member. 
   The spraying unit comprises a guide hole which is formed outside a fixed part of the shaft-flange, and guides the wash water held in the storing unit to a center portion of the rear panel of the rotary drum, an opening formed on the center portion of the rear panel of the rotary drum to correspond to the guide hole, and a nozzle which is mounted inside the rear panel of the rotary drum and includes perforations to spray the wash water passing through the guide hole and the opening into the rotary drum. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
       FIG. 1  is a sectional view showing a drum type washing machine with a conventional water circulation device; 
       FIG. 2  is a side-sectional view showing the structure of a drum type washing machine according to an embodiment of the present invention; 
       FIG. 3  is a sectional view showing a rear part of the drum washing machine shown in  FIG. 2 ; 
       FIG. 4  is a view of a portion “A” encircled in  FIG. 3 ; and 
       FIG. 5  is an exploded perspective view showing a storing unit included in the water circulation device of the drum type washing machine shown in  FIG. 2 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
     FIG. 2  shows a drum type washing machine according to an embodiment of the present invention. The drum type washing machine includes a hexahedral cabinet (“cabinet”)  10  to which a front door  12  is mounted. A fixed drum  20  is horizontally suspended in the cabinet  10  to contain wash water therein. A rotary drum  30  is set inside the fixed drum  20  to be rotatable in opposite directions. The drum type washing machine also includes a drive unit  40  which actuates the rotary drum  30 , and a drain unit  50  which forcibly drains the wash water from the fixed drum  20  in a draining operation. Furthermore, the drum type washing machine is provided with a water circulation device  60  which feeds the wash water in the fixed drum  20  to the rotary drum  30  in washing and rinsing operations. 
   The cabinet  10  defines an outer appearance of the drum type washing machine (“washing machine”), and has a circular opening at its front which allows a user to place laundry in the washing machine or remove the laundry from the washing machine. The front door  12  is hinged to a front of the washing machine to selectively close the circular opening. A transparent window  12   a  made of glass forms a center portion of the front door  12 , so as to allow the user to see the inside of the rotary drum  30  even though the front door  12  is closed. In addition, a detergent container  13  is arranged at an upper position inside the cabinet  10 . Water supplied from an external water supply source passes through a water supply hose  14  and the detergent container  13 , and then is fed into the fixed drum  20 . 
   The fixed drum  20  is a cylindrical drum horizontally suspended in the cabinet  10  by using, for example, a plurality of shock absorbing springs  15  and shock absorbing members  16 . That is, the top of the fixed drum  20  is hung from the top of the cabinet  10  by the shock absorbing springs  15 , while the bottom of the fixed drum  20  is supported at the bottom of the cabinet  10  by the shock absorbing members  16 . A center portion of a rear panel  21  of the fixed drum  20  is integrally provided with a bearing housing  22  in which a bearing  23  and an oil seal  24  are fitted so as to rotatably support a rotating shaft  34  described hereinafter, and prevent the wash water from leaking. 
   The rotary drum  30  is concentrically set inside the fixed drum  20 , and includes a front panel  31 , a rear panel  32  to which the rotating shaft  34  is mounted, and a cylindrical side panel  33 . An opening  31   a  is formed at the front panel  31 , and allows the user to place the laundry into the rotary drum  30  or remove the laundry from the rotary drum  30 . The cylindrical side panel  33  connects the front panel  31  to the rear panel  32 , has a cylindrical shape and is perforated to form spin-drying perforations  33   a . Lifters  33   b  bent to form a “V” shape are regularly placed on the side panel  33  of the rotary drum  30  at angular intervals of 120 degrees, and cause the laundry seated on an internal surface of the rotary drum  30  to repeatedly move upward and be dropped from the top to the bottom inside of the rotary drum  30  during rotation of the rotary drum  30 . 
   A shaft-flange  35  is mounted to the rear panel  32  of the rotary drum  30  by mounting bolts  36 , with the rotating shaft  34  mounted to the shaft-flange  35 . The shaft-flange  35  has, at its center portion, a fixed part  35   a  and mounting parts  35   c  regularly branched from the fixed part  35   a  in radial directions. In this case, the fixed part  35   a  holds one end of the rotating shaft  34 , while the mounting parts  35   c  receive the mounting bolts  36 . The fixed part  35   a  is provided with a shaft holding hole  35   b  (see  FIG. 5 ), so as to firmly hold the one end of the rotating shaft  34  in the shaft holding hole  35   b  through a serration-engagement. That is, the one end of the rotating shaft  34  is mounted to the center portion of the rear panel  32  of the rotary drum  30  by the shaft-flange  35 , whereas the other end is rotatably supported by the bearing  23  set in the bearing housing  22  and is connected to the drive unit  40 . 
   The drive unit  40  is externally mounted to the rear panel  21  of the fixed drum  20 , and includes a stator  41 , a rotor  42 , and a cover  43 . The stator  41  is firmly mounted to an inner circumference of the bearing housing  22 . The rotor  42  is set inside the stator  41 . In this case, the rotating shaft  34  rotatably supported by the bearing  23  is fitted into a center portion of the rotor  42 . The cover  43  is attached to the bearing housing  22  and closes the housing  22 . With an operation of the rotor  42  in conjunction with the stator  41  of the electrically activated drive unit  40 , the rotating shaft  34  is rotated in opposite directions together with the rotary drum  30  by the rotor  42  during the washing and rinsing operations. A control unit (not shown) of this drum type washing machine is programmed so as to rotate the rotor  42  in one direction by controlling a power supply during a spin-drying operation. 
   The drain unit  50  includes a pump  51  which is connected, at its inlet, to a connecting hose  52  to communicate with the bottom of the fixed drum  20 , a three-way valve  53  provided at an outlet of the pump  51 , and a drain hose  54  which is connected to the outlet of the three-way valve  53 . The drain hose  54  discharges the wash water to the outside. The three-way valve  53  switches a flow direction of the wash water according to a mode selection between water draining and circulating modes. The three-way valve  53  includes a first outlet  53   a  connected to the drain hose  54 , and a second outlet  53   b  connected to a guide hose  61   a  of the water circulation device  60 . That is, the three-way valve  53  is actuated so as to have the wash water pumped by the pump  51  flow into the first outlet  53   a  in a draining operation, and flow into the second outlet  53   b  in the washing and rinsing operations. Such an operation of the three-way valve  53  is pre-programmed into the control unit of the washing machine. 
   The water circulation device  60  includes a guide unit  61 , a storing unit  62 , and a spraying unit  63 . The guide unit  61  guides the wash water pumped by the pump  50  between the rear panel  21  of the fixed drum  20  and the shaft-flange  35 . The storing unit  62  defines a storing space  64  which temporarily holds the wash water passing through the guide unit  61 , and is provided between the shaft-flange  35  and the rear panel  21  of the fixed drum  20  to guide the wash water contained in the storing unit  62  to the rear panel  32  of the rotary drum  30 . The spraying unit  63  is provided at a center portion of the rear panel  32  of the rotary drum  30 , and is used to spray the wash water contained in the storing unit  62  into the rotary drum  30 . The construction of the guide unit  61 , storing unit  62 , and spraying unit  63  will be described in detail below with reference to  FIGS. 3-5 . 
   As shown in  FIGS. 3 and 4 , the guide unit  61  includes the guide hose  61   a  and a duct  61   b . The guide hose  61   a  is connected, at its one end, to the second outlet  53   b  of the three-way valve  53 , while being connected, at the other end, to a connecting port  61   c . The connecting port  61   c  is provided at the duct  61   b  which is externally provided on the rear panel  21  of the fixed drum  20 . A communicating hole  61 d is formed on an upper portion of the duct  61   b  to communicate with the storing space  64  of the storing unit  62 . The duct  61   b  having the connecting port  61   c  may be integrated with the rear panel  21  of the fixed drum  20  which is manufactured, for example, through a plastic injection molding method. 
   Referring to  FIGS. 4 and 5 , the storing unit  62  includes a first projecting member  62   a , a second projecting member  62   b , and a sealing unit  62   c . The first projecting member  62   a  has a ring shape, and is provided at a center portion of the rear panel  21  of the fixed drum  20  so as to be projected toward the rotary drum  30 . The second projecting member  62   b  is provided at the shaft-flange  35  so as to be projected toward the rear panel  21  of the fixed drum  20 , and surrounds the first projecting member  62   a . The sealing unit  62   c  is used to seal a gap between the first and second projecting members  62   a  and  62   b.    
   The first projecting member  62   a  may be integrally formed on an inner surface of the rear panel  21  of the fixed drum  20  through, for example, an injection molding method, so as to be concentric with the fixed drum  20 . The second projecting member  62   b  may be integrally manufactured with the shaft-flange  35  made of an aluminum alloy. The second projecting member  62   b  surrounds the first projecting member  62   a  to form the storing space  64  which temporarily holds the wash water around the rotating shaft  34 . The sealing unit  62   c  allows the shaft-flange  35  to be smoothly rotated together with the rotary drum  30  while preventing the wash water held in the storing space  64  from leaking out. The sealing unit  62   c  includes a friction ring  62   d  and a retainer  62   e . In this case, the friction ring  62   d  is interposed between an outer circumference of the first projecting member  62   a  and an inner circumference of the second projecting member  62   b , and is made of, for example, an elastic material. The ring-shaped retainer  62   e  is designed so as to have its outer edge inserted into the friction ring  62   d , and its inner edge mounted to the first projecting member  62   a.    
   To assemble the sealing unit  62   c  with first and second projecting members  62   a  and  62   b , bosses  62   f  each having a screw hole  62   g  are provided along the inner circumference of the first projecting member  62   a  at regular intervals, and through holes  62   h  are formed along the inner edge of the retainer  62   e  at positions corresponding to the screw holes  62   g . Thus, when screws  62   i  are tightened into the screw holes  62   g  after passing the through holes  62   h  aligned with the screw holes  62   g , the sealing unit  62   c  is firmly mounted to the first projecting member  62   a  while the friction ring  62   d  surrounds the outer circumference of the first projecting member  62   a.    
   The spraying unit  63  is used to spray the wash water held in the storing space  64  into the rotary drum  30 . The spraying unit  63  includes a nozzle  63   a , guide holes  63   c , and an opening  63   d . The nozzle  63   a  is internally mounted at the center portion of the rear panel  32  of the rotary drum  30 , and has perforations  63   b . The guide holes  63   c  are radially formed outside the fixed part  35   a  of the shaft-flange  35 , and the opening  63   d  is formed on the center portion of the rear panel  32  to correspond to the guide holes  63   c . In such a construction, the wash water held in the storing space  64  flows into the nozzle  63   a  through the guide holes  63   c  and the opening  63   d , and is sprayed into the rotary drum  30  through the perforations  63   b  of the nozzle  63   a . Such an operation will be described in detail below. 
   An operation and effect of the washing machine having the above structure is as follows. 
   First, a user may open the front door  12 , place laundry in the rotary drum  30 , and manipulate a control panel (not shown) to actuate the washing machine. Where the washing machine is actuated, an appropriate quantity of water is supplied into the fixed drum  20  together with detergent contained in the detergent container  13  according to the amount of the laundry. 
   During washing and rinsing operations, the rotor  42  of the drive unit  40  is rotated in opposite directions, thus making the rotating shaft  34  rotate in the opposite directions along with the rotary drum  30 . As the rotary drum  30  is rotated, the laundry rolls, or is washed by being repeatedly moved upward by the lifters  33   b  and dropped from the top to the bottom inside of the rotary drum  30 . 
   Furthermore, where the pump  51  of the drain unit  50  is actuated during the washing and rinsing operations, the wash water is pumped from a bottom to a top inside of the fixed drum  20 , guided to the three-way valve  53  and the water circulation device  60 , and sprayed from the center portion of the rear panel  32  of the rotary drum  30 , as shown by the arrows of  FIG. 3 . 
   That is, the wash water contained in the fixed drum  20  sequentially passes through the second outlet  53   b  of the three-way valve  53 , the guide hose  61 , and the duct  61   b , and is temporarily held in the storing space  64  of the storing unit  62 . Subsequently, the wash water is fed into the nozzle  63   a  through the guide holes  63   c  and the opening  63   d , and sprayed into the rotary drum  30 , which is rotated in the opposite directions, through the perforations  63   b  of the nozzle  63   a . Such a water circulating operation is continuously repeated during the washing and rinsing operations. In this case, the wash water held in the storing space  64  of the storing unit  62  is fed to the nozzle  63   a  without leaking due to the sealing unit  62   c.    
   Accordingly, the laundry is more rapidly wetted by the wash water sprayed through the nozzle  63   a  in an initial washing operation. In addition, the wash water is directly sprayed onto the laundry, thus achieving an improved and desired washing effect with less consumption of water. 
   Since the detergent sinking to the bottom of the fixed drum  20  is circulated along with the wash water, the detergent is also rapidly dissolved. Therefore, the washing effect is further enhanced, which, in turn, shortens a wash time. 
   In a draining operation, the second outlet  53   b  of the three-way valve  53  is closed while the first outlet  53   a  is opened. Therefore, the wash water forcibly pumped by the pump  51  is discharged to the outside through the drain hose  54 . 
   As described above, a drum type washing machine of the present invention is designed so as to have wash water being pumped by a pump be directly sprayed onto laundry from a center portion of a rear panel of a rotary drum, which is rotated in opposite directions during washing and draining operations. Thus, the circulating wash water allows a detergent to be rapidly dissolved. In addition, the wash water is directly sprayed onto the laundry so as to rapidly wet the laundry, improve the washing effect and consume less water. 
   It is understood that the present invention is not limited to a drum type washing machine having a water circulation device. Rather the water circulation device of the present invention can be applied to other types of washing machines. 
   Although a few embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.