Patent Publication Number: US-10316459-B2

Title: Laundry treatment apparatus

Description:
This application is a continuation of U.S. application Ser. No. 15/197,823, filed Jun. 30, 2016, now pending, which claims the benefit of Korean Patent Application No. 10-2015-0092774, filed on Jun. 30, 2015 and Korean Patent Application No. 10-2016-0073976, filed on Jun. 14, 2016, both of which are hereby incorporated by reference as if fully set forth herein. 
    
    
     BACKGROUND 
     Generally, a laundry treatment apparatus is a generic term for an apparatus that washes laundry (e.g., objects to be washed or objects to be dried), an apparatus that dries laundry, and an apparatus that may perform both washing and drying of laundry. 
     Conventional laundry treatment apparatuses are classified into front loading type laundry treatment apparatuses which are configured such that laundry is introduced through an introduction aperture formed in the front surface of the apparatus and top loading type laundry treatment apparatuses configured such that laundry is introduced through an introduction aperture formed in the upper surface of the apparatus. 
     A top loading type laundry treatment apparatus includes a tub having an introduction aperture formed in the upper surface of the apparatus, a drum rotatably provided inside the tub, and a door for opening and closing the introduction aperture. 
     Some conventional laundry treatment apparatuses having the configuration described above are devised to have a minimum volume in order to wash only a very small amount of laundry. Such a laundry treatment apparatus having a minimum volume has the feature of a very small distance between the introduction aperture and the upper end of the drum. 
     Impurities which are generated inside the tub when the drum is rotated to wash laundry may remain on the door. That is, because a water stream is generated inside the tub while the drum is rotated, there is the possibility that bubbles, which are generated as the detergent are dissolved, or contaminants discharged from the laundry during washing may remain on the door or inside the drum after the washing is completed. 
     In addition, in the conventional laundry treatment apparatus, when the bubbles or contaminants remain on the inner surface of the door or on the circumferential surface of the drum despite the completion of washing, a user may erroneously determine that the washing of laundry is not completed or may suspect the failure of the laundry treatment apparatus. 
     In the conventional laundry treatment apparatus, it is not necessary to minimize the volume of the laundry treatment apparatus, with the result that the tub is relatively high, and the wash water is not stored up to the upper surface of the tub. Even when bubbles are generated, therefore, consideration may not be given to the fact that the bubbles may be stuck to the door. Bubbles or impurities generated during washing of laundry may remain on the door, with the result that the bubbles or the impurities may be stuck to the laundry after the washing is completed, thereby reducing washing efficiency. 
     In the conventional laundry treatment apparatus, when the pressure of the wash water flowing in the additional flow channel is excessively increased, the flow channel may be broken, with the result that the wash water may leak or the wash water may flow backward. The conventional laundry treatment apparatus does not prevent bubbles from being generated in the drum. 
     SUMMARY 
     According to one aspect, a laundry treatment apparatus may include a tub body configured to store water, a tub cover configured to define an upper surface of the tub body, an introduction aperture defined through the tub cover, a supply aperture provided in the tub cover, and configured to enable supply of water into the tub body, a drum that is rotatably provided in the tub body, and that is configured to receive laundry, the drum including an opening in communication with the introduction aperture, a door configured to open and close the introduction aperture, and an ejection unit configured to eject water introduced into the supply aperture to at least one of the door or to the drum. 
     Implementations according to this aspect may include one or more of the following features. For example, the ejection unit may include a chamber configured to guide water supplied through the supply aperture toward the introduction aperture, and a chamber discharge unit configured to discharge water introduced into the chamber to the door. The chamber may include an inlet chamber located under the supply aperture, and a connection chamber configured to guide water introduced into the inlet chamber to the chamber discharge unit. A cross-sectional area of the connection chamber may be smaller than a cross-sectional area of the inlet chamber. A cross-sectional area of the chamber discharge unit may be smaller than a cross-sectional area of the connection chamber. The door may be located above the introduction aperture, and the connection chamber may be configured to tilt to allow water discharged from the chamber discharge unit to be supplied to the door. The door may include a frame rotatably coupled to the tub cover and a window provided in the frame, the window comprising a transparent material, and the connection chamber may be configured to tilt to allow water discharged from the chamber discharge unit to be supplied to the window. The chamber further may include an inlet chamber discharge unit that is defined through the inlet chamber and that is configured to eject water to the drum. The drum may include a cylindrical drum body with the opening defined at an upper surface of the drum, and the inlet chamber discharge unit may be configured to eject water toward at least one of a bottom surface or and a circumferential surface of the drum body. The chamber may further include a connection chamber discharge unit that is defined through the connection chamber and that is configured to eject water to the drum. The drum may include a cylindrical drum body with the opening defined at an upper surface of the drum, and the connection chamber discharge unit may include a plurality of connection chamber discharge units, at least one of the connection chamber discharge units being configured to eject water to a circumferential surface of the drum body. The chamber may further include a pressure reduction unit provided in at least one of the inlet chamber or the connection chamber, the pressure reduction unit being configured to discharge water from the chamber to the drum based on a pressure in the chamber being equal to or greater than a predetermined reference pressure. 
     The laundry treatment apparatus may include a rotating shaft configured to rotate the drum, and a one or more washing unit configured to eject at least some water moved toward the tub cover to the door using centrifugal force generated while the drum is rotated. The rotating shaft may be configured to extend from a bottom surface of the tub body toward the introduction aperture. The washing unit may include a guide that extends from an edge of the tub cover toward the introduction aperture. The washing unit may further include a discharge unit configured to discharge water supplied through the guide in a direction in which the door is located. The washing unit may include a plurality of washing units, at least two of the washing units being arranged to face each other. The guide may include a first guide configured to guide water moved to the tub cover to the discharge unit based on the drum being rotated in a clockwise direction, and a second guide configured to guide water moved to the tub cover to the discharge unit based on the drum being rotated in a counterclockwise direction. The washing unit may further include a barrier that protrudes from the tub cover toward an upper surface of the drum, and the discharge unit may include a first discharge unit that is defined through the barrier and that is configured to discharge water supplied through the first guide, and a second discharge unit that is defined through the barrier and that is configured to discharge water supplied through the second guide. Each of the first discharge unit and the second discharge unit is inclined such that a path of water discharged from the first discharge unit and a path of water discharged from the second discharge unit cross each other. The laundry treatment apparatus may further include a cabinet, and a drawer configured to support the tub body. The laundry treatment apparatus may further include a rotating shaft configured to rotate the drum, where the door includes a frame rotatably coupled to the tub cover, a window provided in the frame such that an inside of the tub body is visible from an outside of the tub body, and a washing guide configured to guide at least some water moved to an edge of the frame to the window using centrifugal force generated while the drum is rotated. An end of the introduction aperture may be concavely bent toward the drum, and an upper part of the inlet chamber may correspond to a shape of the introduction aperture such that the upper part of the inlet chamber is configured to receive the end of the introduction aperture based on the upper part of the inlet chamber being in contact with the end of the introduction aperture. The inlet chamber discharge unit may be provided in an edge of a lower part of the inlet chamber and in a middle portion of the lower part of the inlet chamber. The pressure reduction unit may include a chamber through-hole defined through one of the inlet chamber or the connection chamber, and an elastic body provided in the chamber through-hole that is configured to open the chamber through-hole based on pressure applied to the chamber through-hole being equal to or greater than a reference pressure. The elastic body may be configured to have one end connected to the inlet chamber and the other end separate from the connection chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  are views illustrating an example of a laundry treatment apparatus; 
         FIG. 3  is a view illustrating an example of the coupling relationship between a drawer, a tub, and a drum; 
         FIGS. 4A and 4B  are views illustrating an example of an ejection unit 
         FIGS. 5A and 5B  are views illustrating an example of a washing guide and 
         FIGS. 6 to 7B  are views illustrating a second example of an ejection unit. 
     
    
    
     DETAILED DESCRIPTION 
     As illustrated in  FIGS. 1 and 2 , a laundry treatment apparatus  100  may include a cabinet  2 , a drawer  3  provided to be discharged from the cabinet  2 , a tub  4  provided inside the drawer  3  for storing water therein, and a drum  5  rotatably provided inside the tub  4  for storing laundry therein. 
     The cabinet  2  may serve to define the external appearance of the laundry treatment apparatus  100 , and may also simply serve as a space in which the drawer  3  is received. The cabinet  2  may be provided in the front surface of the apparatus with an opening  21  for the insertion of the drawer  3 . 
     The drawer  3  includes a drawer body  31  configured to be inserted into the inside of the cabinet  2  through the opening  21 , a drawer panel  33  fixed to the front surface of the drawer body  31  for opening and closing the opening  21 , and a drawer cover  35  for forming the upper surface of the drawer body  31 . 
     Because the drawer panel  33  is fixed to the front surface of the drawer body  31 , the drawer panel  33  may serve as a handle for discharging the drawer body  31  from the cabinet  2 . 
     The drawer panel  33  may be provided with a control panel  331 , which is used to input a control command associated with the operation of the laundry treatment apparatus  100  and to notify a user of a message associated with the operation of the laundry treatment apparatus  100 . 
     The drawer body  31  may have any shape that can be inserted into the cabinet  2  through the opening  21  and can provide a space in which the tub  4  is received.  FIG. 1  illustrates a hollow drawer body  31  having a hexahedral shape by way of example. 
     The drawer cover  35  has a first through-hole  351  and a second through-hole  353  for communicating the inside of the drawer body  31  with the outside. The first through-hole  351  may be provided for the introduction and discharge of laundry, and the second through-hole  353  may be provided to supply water required to wash the laundry. 
     As illustrated in  FIG. 2 , the tub  4  includes a tub body  41  located inside the drawer body  31  for storing water therein, and a tub cover  43  for forming the upper surface of the tub body  41 . The tub body  41  may take the form of a cylinder having an open upper surface. A heater  411  for heating water may be provided in the tub body  41 . 
     The tub cover  43  may have an introduction aperture  431  for communicating the inside of the tub body  41  with the outside of the tub body  41 , and a supply aperture  433  for introducing water into the tub body  41 . 
     The introduction aperture  431  may be provided under the first through-hole  351  provided in the drawer cover  35 , and the supply aperture  433  may be provided to communicate with the second through-hole  353  provided in the drawer cover  35 . 
     The introduction aperture  431  serves to allow laundry to be introduced into the tub body  41 , or serves to allow the laundry inside the tub body  41  to be discharged to the outside of the tub body  41 . The introduction aperture  431  is opened and closed by a door  45 . 
     As illustrated in  FIG. 3 , the door  45  may include a frame  451  rotatably coupled to the tub cover  43  via a hinge  453 , a window  455  provided in the frame  451 , and a door handle  457  for separably coupling the frame  451  to the tub cover  43 . The window  455  may be formed of a transparent material to allow the user to view the inside of the tub body  41  when the drawer  3  is discharged from the cabinet  2 . 
     Meanwhile, in order to prevent the water inside the tub body  41  from being discharged to the outside of the tub body  41  through the introduction aperture  431 , any one of the frame  451  and the tub cover  43  may be provided with a sealing unit  49  for hermetically sealing a space between the frame  451  and the introduction aperture  431  when the door  45  closes the introduction aperture  431 . 
     The tub  4  having the configuration described above is coupled to the drawer body  31  via a tub support unit  6 . The tub support unit  6  may include a first support member  61  provided at the drawer body  31 , a second support member  63  provided at the tub body  41 , and a connector  65  for connecting the first support member  61  and the second support member  63  to each other. 
     The connector  65  may include a first connection piece  651  configured to be seated in the first support member  61 , a second connection piece  653  for supporting the second support member  63 , and a bar  655  for connecting the first connection piece  651  and the second connection piece  653  to each other. 
     The first connection piece  651  may be shaped to be movable in the first support member  61  while being seated in the first support member  61 . The second connection piece  653  may be shaped to support the second support member  63  and to be movable in the second support member  63 . 
     As illustrated in  FIG. 2 , the bar  655  may form a right angle with respect to the bottom surface of the cabinet  2  (i.e. may be provided parallel to the height direction Z of the cabinet  2  or provided to be orthogonal to the bottom surface of the drawer  3 ). 
     At least three tub support units  6  are provided to couple the tub body  41  to the drawer body  31 , and the bars  655  form a right angle with respect to the bottom surface of the cabinet  2 . The distance between the tub cover  43  and the drawer cover  35  may be increased when compared to the case where the bars  655  are tilted at a prescribed angle relative to the Z-axis. 
     The tub support units  6  may reduce the possibility of the tub cover  43  colliding with the drawer cover  35  when the tub body  41  vibrates inside the drawer body  31 . 
     When the bars  655  are provided to form a right angle with respect to the bottom surface of the drawer  3 , at least one of the first support member  61  and the second support member  63  may be separably coupled to the drawer body  31 . 
     When at least three tub support units  6  are provided and both the first support member  61  and the second support member  63  are inseparable from the drawer body  31 , a user who attempts to fix the tub body  41  to the drawer body  31  first needs to insert the tub body  41  into the drawer body  31  to prevent the first support member  61  from interfering with the second support member  63 , and then needs to rotate the tub body  41  so that the second support member  63  and the first support member  61  are located on the vertical axis, in order to couple the first connection piece  651  to the first support member  61 . 
     Although the feature by which the bar  655  of the tub support unit  6  is provided to form a right angle with respect to the bottom surface of the drawer  3  serves to minimize the distance between the outer circumferential surface of the tub body  41  and the inner circumferential surface of the drawer body  31  to minimize the volume of the laundry treatment apparatus  100 , the strength of assembly of the first connection piece  651  and the first support member  61  may be deteriorated while the process described above is performed. This problem may be solved by making the first support member  61  separable from the drawer body  31 . 
     The drum  5 , which is provided inside the tub  4 , may include a cylindrical drum body  51  having an opening  53  formed in the upper surface thereof. The opening  53  is located below the introduction aperture  431 , and the laundry supplied through the introduction aperture  431  may be supplied to the drum body  51  through the opening  53 . 
     A plurality of drum through-holes  59  may be provided in the bottom surface  57  and the circumferential surface  55  of the drum body  51  for communication of the inside of the drum body  51  and the tub body  41 . 
     The drum body  51  may be rotated inside the tub body  41  by a drive unit. The drive unit may include a stator M 1  located outside the tub body  41  and fixed to the bottom surface of the tub body  41 , a rotor M 2  configured to be rotated by a rotating magnetic field provided by the stator M 1 , and a rotating shaft M 3  penetrating the bottom surface of the tub body  41  for connecting the bottom surface  57  of the drum  5  and the rotor M 3  to each other. The rotating shaft M 3  may be provided to form a right angle with respect to the bottom surface of the tub body  41 . 
     The laundry treatment apparatus  100  may supply water to the tub  4  via a water supply unit  7 , and may discharge the water stored in the tub  4  to the outside of the cabinet  2  via a drain unit  8 . 
     As illustrated in  FIG. 2 , the water supply unit  7  may include a first water supply pipe  71  connected to the supply aperture  433  formed in the tub cover  43 , a second water supply pipe  73  connected to a water supply source, which is located at the outside of the cabinet  2 , and a connection pipe  75  fixed to the tub cover  43  for connecting the first water supply pipe  71  and the second water supply pipe  73  to each other. 
     The first water supply pipe  71  may connect the supply aperture  433  and the connection pipe  75  to each other through the second through-hole  353  provided in the drawer cover  35 . The first water supply pipe  71  may be a corrugated pipe in order to prevent the first water supply pipe  71  from being separated from the connection pipe  75  when the tub  4  vibrates (see  FIG. 3 ). 
     In addition, the second water supply pipe  73  may also be a corrugated pipe in order to prevent the second water supply pipe  73  from being separated from the connection pipe  75  when the drawer  3  is discharged from the cabinet  2 . The second water supply pipe  73  may be opened and closed by a water supply valve  77 , which is controlled by a controller. 
     In some examples, the water supply unit  7  may include a single water supply pipe for connecting a water supply source, which is located at the outside of the cabinet  2 , to the supply aperture  433  provided in the tub cover  43 . In this example, the water supply pipe may be a corrugated pipe. 
     The drain unit  8  may include a drain pump  81  fixed to the drawer body  31 , a first drain pipe  83  for guiding the water inside the tub body  41  to the drain pump  81 , and a second drain pipe  85  for guiding the water discharged from the drain pump  81  to the outside of the cabinet  2 . The second drain pipe  85  may be a corrugated pipe. 
     In the laundry treatment apparatus  100 , after laundry is introduced into the drum  5  and water and detergent are supplied to the tub  4 , the drum  5  is rotated via the drive unit to wash the laundry. 
     Because a water stream is generated inside the tub  4  while the drum  5  is rotated, there is the possibility that bubbles, which are generated as the detergent is dissolved, or contaminants discharged from the laundry during washing may remain on the door  45  after the washing is completed. 
     When bubbles or contaminants remain on the inner surface of the door  45  despite the completion of washing, the user may erroneously determine that the washing of laundry is not completed or may suspect the failure of the laundry treatment apparatus  100 . 
     The laundry treatment apparatus  100  may further include at least one of a washing unit  91  and an ejection unit  93  for removing impurities (bubbles, contaminants or the like) remaining on the door  45 . 
     As illustrated in  FIGS. 4A and 4B , the washing unit  91  serves to wash the door  45  using the centrifugal force generated while the drum  5  is rotated. 
     In the drum  5 , because the rotating shaft M 3 , which forms the center of rotation, forms a right angle with respect to the bottom surface of the tub body  41 , the water inside the tub  4  is moved upward along the circumferential surface of the tub body  41  by centrifugal force while the drum  5  is rotated, and thereafter is moved to the introduction aperture  431  along the tub cover  43 . The washing unit  91  may serve to discharge the water, moved to the tub cover  43  by centrifugal force, in the direction in which the door  45  is located, thereby washing the door  45 . 
     The washing unit  91  may include a guide  915  extending from the edge of the tub cover  43  toward the introduction aperture  431 , a barrier  911  protruding from the tub cover  43  toward the upper surface of the drum  5 , and a discharge unit  913  formed through the barrier  911  for the discharge of water, supplied through the guide  915 , in the direction in which the door  45  is located. 
     The barrier  911  may be provided to surround the entire introduction aperture  431 , as illustrated in  FIG. 4B . In some examples, a plurality of barriers may be spaced apart from one another along the edge of the introduction aperture. 
     As illustrated in  FIG. 4B  the barrier  911  may protrude from the edge of the introduction aperture  431  toward the drum  5 . 
     When the door  45  is rotatably coupled to the upper surface of the tub cover  43  so that the inner surface of the door  45  (i.e. the surface of the door  45  that is in contact with water) is located higher than the discharge unit  913 , the discharge unit  913  may be inclined at a prescribed angle to allow water to be discharged toward the door  45 . 
     In addition, when the door  45  includes the window  455  formed of a transparent material, the discharge unit  913  may be inclined to allow water to be discharged to the window  455 . 
     The guide  915  may include a first guide  915   a  and a second guide  915   b . The first guide  915   a  guides water, moved to the edge of the tub cover  43 , to the discharge unit  913  when the drum  5  is rotated in the clockwise direction. The second guide  915   b  guides water, moved to the edge of the tub cover  43 , to the discharge unit  913  when the drum  5  is rotated in the counterclockwise direction. 
     In the case where the discharge unit  913  is a single hole formed in the barrier  911 , the respective guides  915   a  and  915   b  may guide water to the same discharge unit  913 . However, in the case where the discharge unit  913  includes a first discharge unit  913   a  and a second discharge unit  913   b  formed in the barrier  911 , the first guide  915   a  may guide water to the first discharge unit  913   a , and the second guide  915   b  may guide water to the second discharge unit  913   b.    
     The washing unit  91  may wash the door  45  regardless of the direction in which the drum  5  is rotated so long as the number of revolutions per minute of the drum  5  is a preset reference number of revolutions per minute (i.e. the number of revolutions per minute by which the water inside the tub body  41  is moved upward to the tub cover  43 ). 
     In addition, the respective discharge units  913   a  and  913   b  may be inclined at a prescribed angle so that the path of water discharged from the first discharge unit  913   a  and the path of water discharged from the second discharge unit  913   b  cross each other. This serve to increase the washing range of the washing unit  91 . 
     The washing unit  91  may be provided in a plural number along the edge of the introduction aperture  431 , and the washing units  91  may be arranged to surround the introduction aperture  431 . In addition, at least two of the washing units  91  may be arranged s to face each other. This may serve to increase the washing capability of the washing unit  91 . 
     The impurities remaining on the door  45  may be removed by a washing guide  456  illustrated in  FIGS. 5A and 5B . The washing guide  456  may be provided at the edge of the window  455 . During the rotation of the drum, water in the tub may move from the bottom surface of the tub to the edge of the frame  451  due to centrifugal force generated while the drum is rotated. The water may move around the edge of the frame  451 . In the case in which the washing guide  456  is provided at the edge of the window, the water moving around the edge of the frame  451  may be guided toward the middle of the window  455  (W 1  and W 2 ). Consequently, it is possible to prevent the impurities from remaining on the window by the provision of the washing guide  456 . 
     In order to maximize the washing area, the washing guide  456  may include a first washing guide  456   a  and a second washing guide  456   b  disposed so as to be symmetric with respect to a line of symmetry Q of the door  45 , as illustrated in  FIG. 5B . 
     In some examples, one of the washing unit  91  and the washing guide  456  may be provided, and in some other examples both the washing unit  91  and the washing guide  456  may be provided. 
     The ejection unit  93  illustrated in  FIG. 6  may be configured to eject water supplied to the tub  4  to at least one of the door  45  and the drum  5  to wash the door  45 . The ejection unit  93  may include a chamber  931  for guiding water, supplied to the supply aperture  433  provided in the tub cover  43 , toward the introduction aperture  431 , and a chamber discharge unit  933  for discharging the water introduced into the chamber  931  to the door  45 . 
     The chamber  931  includes an inlet chamber  931   a  located under the supply aperture  433 , and a connection chamber  931   b  for guiding the water introduced into the inlet chamber  931   a  to the chamber discharge unit  933 . 
     As illustrated in  FIGS. 7A and 7B , the inlet chamber  931   a  may have a communication hole  931   e  connected to the supply aperture  433 . In order to increase the pressure of water to be discharged through the chamber discharge unit  933 , the cross-sectional area A 1  of the connection chamber  931   b  may be smaller than the cross-sectional area of the inlet chamber  931   a . In addition, the cross-sectional area A 2  of the chamber discharge unit  933  may be smaller than the cross-sectional area A 1  of the connection chamber  931   b.    
     The connection chamber  931   b  may be tilted at a prescribed angle so that water ejected from the chamber discharge unit  933  is supplied to the door  45 , which is located above the introduction aperture  431 . 
     In some examples where the door  45  includes the window  455 , the tilt angle of the connection chamber  931   b  may be set to an angle at which water ejected from the chamber discharge unit  933  may be supplied to the window  455 . 
     The inlet chamber  931   a  may further include an inlet chamber discharge unit  935  for ejecting some of the water inside the inlet chamber  931   a  into the drum  5 . 
     The inlet chamber discharge unit  935  may be provided to eject water toward the bottom surface  57  of the drum body, or may be provided to eject water toward the circumferential surface  55  of the drum body. 
     When the inlet chamber discharge unit  935  is provided to eject water toward the bottom surface  57  of the drum body, the inlet chamber discharge unit  935  may serve to remove bubbles generated inside the drum  5  by ejecting water into the drum  5  during washing. 
     When the controller controls the water supply valve  77  during washing to supply water to the chamber  931 , bubbles generated inside the tub  4  during washing are removed, which may prevent impurities, including the bubbles, from remaining on the door  45 . 
     In other examples, when the inlet chamber discharge unit  935  is provided to eject water toward the circumferential surface  55  of the drum body, the inlet chamber discharge unit  935  may serve to wash the circumferential surface  55  of the drum  5 . 
     When the controller controls the water supply valve  77  to supply water to the chamber  931  after washing is completed and also rotates the drum  5 , impurities remaining on the surface of the drum  5  may be washed by the water discharged from the inlet chamber discharge unit  935 . 
     In addition, the connection chamber  931   b  may further have a connection chamber discharge unit  937  for discharging water to the drum  5 . 
     At least two connection chamber discharge units  937  may be provided. In some examples, one connection chamber discharge unit  937  may be provided to discharge water toward the bottom surface  57  of the drum body, and the other connection chamber discharge unit  937  may be provided to discharge water toward the circumferential surface  55  of the drum body. 
     The inlet chamber discharge unit  935  and the connection chamber discharge unit  937  may be disposed at the edge of the drum  5  toward the center of rotation of the drum  5 . When the drum  5  is rotated, therefore, it is possible to eject water over the entire area of the drum, thereby effectively removing bubbles from the drum. 
     In some examples, the door  45  may open the introduction aperture  431  due to the discharge of water from the chamber discharge unit  933  when the pressure of the water supplied through the water supply unit  7  is high (i.e. the pressure in the chamber  93  is high). 
     The chamber  93  may further include a pressure reduction unit  931   c  for discharging water from the chamber  93  to the drum  5  when the pressure in the chamber is equal to or greater than a predetermined reference pressure. 
     The pressure reduction unit  931   c  may be provided in at least one of the inlet chamber  931   a  and the connection chamber  931   b .  FIGS. 7A and 7B  illustrates an example in which the pressure reduction unit  931   c  is provided in the connection chamber  931   b.    
     The pressure reduction unit  931   c  may include a chamber through-hole  931   d  formed through the connection chamber  931   b  and an elastic body  931   f  provided in the chamber through-hole  931   d  for opening the chamber through-hole  931   d  when the pressure in the connection chamber  931   b  is equal to or greater than a reference pressure. The laundry treatment apparatus may prevent impurities, generated inside a tub during washing from remaining on a door. 
     The laundry treatment apparatus may wash the door using the centrifugal force generated by water stored in a tub while a drum is rotated. The laundry treatment apparatus may include an ejection unit for washing a door using a device for supplying water to a tub. The laundry treatment apparatus may include an additional flow channel for removing bubbles or impurities from a door, and may selectively drain water from a device for removing bubbles or impurities when the pressure in the device for removing bubbles or impurities is excessively increased, thereby preventing water leakage or the backward flow of wash water.