Patent Publication Number: US-10774455-B2

Title: Washing machine

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY 
     This application claims the benefit of Korean Patent Application No. 10-2015-0161487, filed on Nov. 18, 2015 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     Embodiments of the present disclosure relate to a washing machine for allowing a user to easily put laundry into or take laundry out of the washing machine. 
     BACKGROUND 
     Generally, a washing machine is an apparatus to wash laundry using electricity. Washing machines are classified into a drum washing machine and a vertical-axis washing machine. The drum washing machine is provided with a rotary tub horizontally arranged, such that laundry is washed by having the laundry lifted along an inner circumferential surface of a rotary tub and fallen when the rotary tub rotates about a horizontal axis thereof in forward and backward directions. The vertical-axis washing machine is provided with a rotary tub including a pulsator vertically arranged, such that laundry is washed using a water stream generated by the pulsator when the rotary tub rotates about a vertical axis thereof in forward and backward directions. 
     Generally, the drum washing machine includes a cabinet, a tub placed within the cabinet to store wash water therein, and a drum rotatably installed in the tub to receive laundry to be washed therein. An opening may be provided in the cabinet, and the opening may be opened or closed by a door. 
     The drum rotates to agitate laundry along with wash water on the condition that the laundry, detergent, and the wash water are put into the drum, such that dirt or stains are removed from the laundry. The laundry is put into the tub through the opening provided in the cabinet, and detergent and wash water are supplied by a detergent supply device. 
     If a washing process of the drum washing machine starts operation, the door of the drum washing machine remains locked. In order to allow laundry to be easily put into or taken out of the drum during the washing process, the door of the drum washing machine may include an auxiliary door to be freely opened or closed at any time desired by a user. 
     If the auxiliary door is opened during the washing process, detergent bubbles generated in the drum may leak outside through the opening opened or closed by the auxiliary door. 
     SUMMARY 
     Therefore, it is an aspect of the present disclosure to provide a washing machine having an improved structure for preventing leakage of detergent bubbles generated in the drum located into a space behind the auxiliary door. 
     It is another aspect of the present disclosure to provide a washing machine having an improved structure of a sealing part located in an opening part opened or closed by an auxiliary door so that bubbles in the drum are prevented from flowing through the opening part 
     Additional aspects 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. 
     In accordance with one aspect of the present disclosure, a washing machine includes: a cabinet including a first opening; a tub disposed in the cabinet and configured to store wash water; a drum rotatably disposed in the tub; a door assembly mounted to the cabinet to open or close the first opening and including a second opening; an auxiliary door configured to open or close the second opening; and an interference part located at a rear of the auxiliary door to form a predetermined space in the rear part of the auxiliary door. 
     The interference part may be an auxiliary door glass mounted to the auxiliary door. 
     The auxiliary door glass may protrude backward of the auxiliary door. 
     The auxiliary door glass may simultaneously move together with the auxiliary door. 
     The washing machine may further include a connection part configured to connect the auxiliary door to the drum. 
     When the auxiliary door is closed, the auxiliary door glass may be accommodated in the connection part. 
     A sealing member may be mounted to the outer side of the auxiliary door glass. 
     The sealing member may seal a space between the auxiliary door glass and the connection part when the auxiliary door is closed. 
     The auxiliary door glass may include: a side surface part protruding backward from the auxiliary door; and a rear surface part connected to the side surface part and located to face the auxiliary door. 
     The auxiliary door and the auxiliary door glass may be formed of transparent material. 
     The washing machine may further include a connection part configured to connect the auxiliary door to the drum. 
     One side of the connection part may be opened or closed by a cap. 
     The cap may close one side of the connection part in so far as no external force occurs. 
     The cap may be configured to rotate about a rotation shaft. 
     The rotation shaft may include an elastic member configured to provide the cap with an elastic force in a direction the cap closes the one side of the connection part. 
     The cap may open the one side of the connection part by an external force in an opposite direction to the elastic force applied to the elastic member. 
     The cap may be spaced apart from the auxiliary door. 
     The washing machine may further include: a front sealing part located at a front of the connection part to seal a space between the connection part and the auxiliary door. 
     A portion of a lower part of the front sealing part may be extended upward to partially cover the second opening. 
     The front sealing part may be formed of material that enables the front sealing part to be deformed by an external force. 
     In accordance with another aspect of the present disclosure, a washing machine includes: a cabinet including a first opening; a drum disposed in the cabinet to store wash water therein; a door assembly mounted to the cabinet to open or close the first opening, and including a second opening; an auxiliary door configured to open or close the second opening; and an interference part located at a rear of the auxiliary door to prevent the auxiliary door from making contact with wash water or detergent bubbles in the drum. 
     The interference part may be an auxiliary door glass mounted to a rear of the auxiliary door while protruding backward of the auxiliary door. 
     The washing machine may further include a connection part configured to connect the auxiliary door to the drum. 
     The connection part may include a cap configured to selectively open one side of the connection part. 
     An elastic member is connected to the cap such that an elastic force of the elastic member allows the cap to keep shielding the one side of the connection part unless an external force occurs. 
     The connection part may include a front sealing part configured to seal a space between the connection part and the auxiliary door. 
     The front sealing part may cover at least one portion of the second opening. 
     The front sealing part may be formed of material which allows the front sealing part to be deformed by an external force. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects 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: 
         FIG. 1  is a perspective view illustrating an external appearance of a washing machine according to an embodiment of the present disclosure. 
         FIG. 2  is a cross-sectional view illustrating a washing machine according to an embodiment of the present disclosure. 
         FIG. 3  is a view illustrating a cabinet and a door assembly of the washing machine separated from each other according to an embodiment of the present disclosure. 
         FIG. 4  is an exploded perspective view illustrating a door assembly according to an embodiment of the present disclosure. 
         FIG. 5  is a view illustrating a door assembly according to an embodiment of the present disclosure. 
         FIG. 6  is a view illustrating an auxiliary door included in a door assembly which is opened according to an embodiment of the present disclosure. 
         FIG. 7  is a view illustrating a door assembly according to another embodiment of the present disclosure. 
         FIG. 8  is a view illustrating an auxiliary door included in a door assembly which is opened according to another embodiment of the present disclosure. 
         FIG. 9  is a view illustrating a door assembly according to still another embodiment of the present disclosure. 
         FIG. 10  is a view illustrating an auxiliary door included in a door assembly which is opened according to still another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
       FIG. 1  is a perspective view illustrating an external appearance illustrating a washing machine according to an embodiment of the present disclosure.  FIG. 2  is a cross-sectional view illustrating a configuration of a washing machine according to an embodiment of the present disclosure. 
     Referring to  FIGS. 1 and 2 , the washing machine  100  may include a cabinet  10 , a tub to receive wash water to be used for a washing process or rinse water to be used for a rinsing process, and a drum  30  to accommodate laundry therein. 
     The cabinet  10  may include input units  81   a  and  81   b  to receive operation commands for the washing machine  1  from a user, and a control panel  80  including a display  83  displaying operation information of the washing machine  1 . 
     The input units  81   a  and  81   b  may receive user commands related to the operations of the washing machine  1 , for example, various commands related to a washing time, the number of rinsing times, a dehydration time, a drying time, operation start/stop/pause functions, etc. The input units  81   a  and  81   b  may include a press button  81   a  and a rotary button  81   b . In addition, the display  83  may display information regarding the operations of the washing machine  1 , for example, the amount of wash water, a current execution process of the washing machine  1 , the remaining time to complete laundry washing, etc. The display  83  may include a Liquid Crystal Display (LCD) panel, a Light Emitting Diode (LED) panel, etc. 
     Although the washing machine  1  according to the embodiment includes the input units  81   a  and  81   b  and the display  83  separated from the input units  81   a  and  81   b  for convenience of description, the scope or spirit of the present disclosure is not limited thereto, and it should be noted that the washing machine  1  may include a Touch Screen Panel (TSP) in which the input units  81   a  and  81   b  are incorporated with the display  83  as necessary. 
     The cabinet  10  includes frames  10   a ,  10   b ,  10   c  and  10   d . The frames  10   a ,  10   b ,  10   c  and  10   d  may include a top frame  10   a  to form a top surface of the cabinet  10 , a front frame  10   b  to form a front surface of the cabinet  10 , a rear frame  10   c  to form a rear surface of the cabinet  10 , and a side frame (not shown) and a bottom frame  10   d  to respectively form a side surface and a bottom surface of the cabinet  10  while connecting the front frame  10   b  to the rear frame  10   c.    
     A first opening  2   a  may be formed at the front frame  10   b  of the cabinet  10  such that a user can put laundry into or withdraw laundry from the drum  30  through the first opening  2   a . The first opening  2   a  may be opened or closed by a door assembly  110  installed at the front frame  10   b  of the cabinet  10 . 
     A diaphragm  90  may connect the cabinet  10  to the tub  20 . In detail, the diaphragm  90  may be disposed between the first opening  2   a  of the cabinet  10  and an opening  21  of the tub  20  corresponding to the first opening  2   a.    
     The diaphragm  90  may form a passage from the first opening  2   a  of the cabinet  10  to the opening  21  of the tub  20 . During rotation of the drum  30 , the diaphragm may reduce vibration delivered to the front frame  10   b . Some parts of the diaphragm  90  may be disposed between the door assembly  110  and the front frame  10   b  so as to prevent wash water of the tub  20  from leaking outside the cabinet  10 . 
     The diaphragm  90  may include an injection-molded product formed of a thermoplastic elastomer. Since the thermoplastic elastomer has elasticity at the room temperature in the same manner as in rubber, the diaphragm  90  formed of the thermoplastic elastomer may effectively reduce vibration delivered from the tub  20  to the front frame  10   b  of the cabinet  10 . 
     A spring  17  may be provided between the tub  20  and the cabinet  10  to support the tub  20  at an upper portion of the washing machine  100 . The spring  17  may reduce vibration and noise generated by movement of the tub  20  through elastic force. 
     A water supply pipe  13  to supply water (wash water or rinse water) to the tub  20  may be installed at an upper portion of the tub  20 . A water supply valve  14  may be installed at one side of the water supply pipe  13 . 
     A detergent supply device  40  may be connected to the tub  20  through a connection pipe  16 . Water received through the water supply pipe  13  may be mixed with detergent through a detergent supply device  40 , and then supplied into the tub  20 . 
     The tub  20  may be supported by a damper  42 . The damper  42  may connect the outer surface of the tub  20  to the inner bottom surface of the cabinet  10 . In addition, the damper  42  may also be located at the upper side and the left and right sides of the cabinet  10  in addition to the inside bottom surface of the cabinet  10  so as to support the tub  20 . The damper  42  or the spring  17  may attenuate vibration and impact caused by vertical motion of the tub  20  above and below the tub  20 . 
     The tub  20  may be supported by at least one damper  42 . 
     The rear surface of the drum  30  may be connected to a drive shaft  11  to which a drive motor  7  transmits power. A plurality of through-holes  27  through which wash water passes may be formed around the drum  30 . A plurality of lifters  26  may be installed on an inner circumferential surface of the drum  30  so that laundry may be lifted or fallen during rotation of the drum  30 . 
     The drive shaft  11  may be disposed between the drum  30  and the drive motor  7 . One end of the drive shaft  11  may be connected to a rear plate of the drum  30 , and the other end of the drive shaft  11  may extend outside a rear wall of the tub  20 . When the drive motor  7  drives the drive shaft  11 , the drum  30  connected to the drive shaft  11  may rotate around the drive shaft  11 . 
     The rear wall of the tub  20  is provided with a bearing housing  8  so as to rotatably support the drive shaft  11 . The bearing housing  8  may be formed of aluminum alloy, and be inserted into the rear wall of the tub  20  during injection molding of the tub  22 . Bearings  9  may be installed between the bearing housing  8  and the drive shaft  11  so that the drive shaft  11  may be smoothly rotated. 
     The tub  20  is provided, at a lower portion thereof, with a drain pump  4  to discharge water within the tub  20  to the outside of the cabinet  10 , a connection hose  3  connecting the tub  20  to the drain pump  4  such that water in the tub  20  may be introduced into the drain pump  4 , and a drain hose (not shown) configured to guide water pumped by the drain pump  4  to the outside of the cabinet  10 . 
     The door assembly  110  may include a door frame  120  provided to be pivot with respect to the cabinet  10 . 
       FIG. 3  is a view illustrating a cabinet and a door assembly of the washing machine which are separated from each other according to an embodiment of the present disclosure.  FIG. 4  is an exploded perspective view illustrating the door assembly according to an embodiment of the present disclosure.  FIG. 5  is a view illustrating the door assembly according to an embodiment of the present disclosure. 
     Referring to  FIGS. 3 to 5 , the door assembly  110  provided in the washing machine  100  may include a door frame  120  configured to pivot with respect to the cabinet  10 . 
     The door frame  120  may include a front cover  130  and a rear holder  140 . 
     The front cover  130  may form the front surface of the door frame  120 , and the rear holder  140  may form at least one portion of the rear surface of the door frame  120 . The rear holder  140  may be provided to correspond to the first opening  2   a . When the door assembly  110  covers the first opening  2   a , the rear holder  140  may make contact with the first opening  2   a.    
     The door assembly  110  may include a door glass  170 . When the door assembly  110  is positioned to cover the first opening  2   a , the door glass  170  may seal the interior of the cabinet  10  by making contact with the diaphragm  90 . 
     The door frame  120  may include a second opening  180   a  configured to be opened or closed independently of the first opening  2   a . The door assembly  110  may include an auxiliary door  160  configured to open or close the second opening  180   a . The first opening  2   a  may be opened or closed by the door frame  120 , and the second opening  180   a  may be opened or closed by the auxiliary door  160 . The first opening  2   a  and the second opening  180   a  may be independently opened or closed from each other. 
     The second opening  180   a  may be one part of the first opening  2   a , or the second opening  180   a  may be provided not to overlap the first opening  2   a . For example, the second opening  180   a  may form a part of the first opening  2   a  while overlapping an upper part of the first opening  2   a . The second opening  180   a  may also be separately provided over the first opening  2   a . The following embodiment will disclose an exemplary case in which the second opening  180   a  forms an upper part of the first opening  2   a.    
     The second opening  180   a  is provided on the first opening  2   a . Thus, although the auxiliary door  160  is opened during the washing operation, wash water or detergent bubbles in the drum  30  may be prevented from leaking outside through the second opening  180   a.    
     Even when the first opening  2   a  is closed by the door frame  120 , the user may additionally put laundry or detergent into the cabinet through the second opening  180   a  by opening the auxiliary door  160 . The door assembly  110  may include a door pivoting part  190  and a door locking part  192 . The door frame  120  may pivot about the door pivoting part  190  with respect to the cabinet  10 . The door pivoting part  190  may be connected to one side of the door frame  120 . The door pivoting part  190  may allow the door frame  120  to rotate with respect to the cabinet  10  to open or close the first opening  2   a.    
     The door locking part  192  may be coupled to the other side of the door frame  120 . When the door frame  120  covers the first opening  2   a , the door frame  120  is kept locked by the door locking part  192  unless receiving an external force. An insertion part corresponding to the door locking part  192  may be provided in the cabinet  10 . When the door frame  120  covers the first opening  2   a , the door locking part  192  may be inserted into the inserting part. 
     The front cover  130  may include a cover body  132 . The cover body  132  may be provided with a cover opening  134 . When the front cover  130  is closed, the cover opening  134  may be positioned to correspond to the second opening  180   a . A front end of a connection part  180  forming the second opening  180   a  may be positioned at an inside of the cover opening  134 . The cover body  132  may be provided to form the front surface of the door assembly  110 . 
     The auxiliary door  160  may open or close the second opening  180   a . The auxiliary door  160  may pivot with respect to the front cover  130 . 
     The auxiliary door  160  may include an auxiliary door body  162  corresponding to the second opening  180   a , and an auxiliary door hinge part  164  provided at one side of the auxiliary door body  162  such that the auxiliary door body  162  is able to be pivoted. The auxiliary door hinge part  164  may be provided at one side of the cover body  133 . 
     The auxiliary door body  162  may have a width equal to or larger than the width of the second opening  180   a , such that the second opening  180   a  is stably closed when the auxiliary door  160  closes the second opening  180   a.    
     The auxiliary door  160  may include an auxiliary door glass  166 . The auxiliary door glass  166  may be positioned at the rear of the auxiliary door body  162 . The auxiliary door glass  166  may be mounted to the rear of the auxiliary door body  162  so as to be pivoted together with the auxiliary door body  162  about the auxiliary door hinge part  164 . When the auxiliary door  160  is closed, the auxiliary door glass  166  may be accommodated in the connection part  180  configured to connect the auxiliary door  160  to the drum  30 . 
     The auxiliary door body  162  and the auxiliary door glass  166  may be formed of transparent material such that a user who is located outside the washing machine  100  may view the inner space of the drum  30  on the condition that the auxiliary door  160  closes the second opening  180   a . The auxiliary door body  162  and the auxiliary door glass  166  may be formed of opaque material. 
     The auxiliary door glass  166  may convexly protrude backward from the auxiliary door body  162 . The auxiliary door glass  166  may include a side surface part  166   a  protruding backward from the auxiliary door body  162 . A front end of the side surface part  166   a  may be mounted to the auxiliary door body  162 . The side surface part  166   a  may be provided at a rear side thereof with a rear surface part  166   b  connected to the side surface part  166   a . A predetermined space  167  may be provided by the auxiliary door glass  166 , the side surface part  166   a  of the auxiliary door glass  166  and the rear surface part  166   b  of the auxiliary door glass  166 . 
     In this case, when the side surface part  166   a  of the auxiliary door glass  166  protrudes backward from the auxiliary door body  162  by a length identical to or shorter than a length by which the door glass  170  protrudes backward of the front cover  130 . 
     A sealing member  168  may be mounted to the rear of the auxiliary door glass  166 . The sealing member  168  may be provided in a shape corresponding to the outer surface of the auxiliary door glass  166 . For example, when the side surface part  166   a  of the auxiliary door glass  166  is formed in a cylindrical shape, the sealing member  168  may be formed in a ring shape surrounding the outer surface of the side surface part  166   a.    
     When the auxiliary door  160  is closed, the sealing member  168  may make contact with the inner surface of the connection part  180  such that the space between the auxiliary door glass  166  and the connection part  180  is sealed. The space between the auxiliary door glass  166  and the connection part  180  is sealed by the sealing member  168 , so that wash water stored in the drum  30  is prevented from leaking to the space between the auxiliary door glass  166  and the connection part  180  during the washing operation. 
     As described above, the auxiliary door glass  166  is formed to protrude backward from the auxiliary door body  162  such that water and detergent bubbles in the drum  30  do not leak to the outside of the washing machine  100  even when the auxiliary door  160  is opened during the washing operation. In addition, the space between the auxiliary door glass  166  and the connection part  180  is sealed by the sealing member  168  so as to prevent leakage of wash water and detergent bubbles, such that leakage of wash water or detergent bubbles attached to the outer surface of the auxiliary door glass  177  may be prevented when the auxiliary door  160  is opened. 
     The front cover  130  may include an auxiliary door seating part  136 . The auxiliary door seating part  136  may be concaved from the outer surface of the front cover  130 . According to the structure, when the auxiliary door  160  closes the second opening  180   a , at least one part of the auxiliary door body  162  is seated on the auxiliary door seating part  136 , so that the second opening  180   a  is stably kept closed by the auxiliary door  160 . In addition, according to the structure, a step difference between the outer surface of the auxiliary door  160  and the outer surface of the front cover  130  under the condition that the second opening  180   a  is closed by the auxiliary door  160  may be reduced or removed so that product quality and aesthetics may be improved. 
     The front cover  130  may include a front glass hole  138  formed to correspond to the door glass  170 . The front glass hole  138  may be formed as an opening such that a user may view the inner space of the drum  30  through the door glass  170  arranged at the rear of the front cover  130 . The front glass hole  138  may be provided at a lower side of the cover opening  134 . Although the front glass hole  138  is illustrated as being formed as an opening, the present disclosure is not limited thereto. For example, the front glass hole  138  may be provided with a light transmission member (not shown) formed of transparent material so as to protect the door glass  170 . 
     The door glass  170  may be formed of transparent material such that a user may view the inner space of the cabinet  10  through the door glass  170  even when the first opening  2   a  is closed by the door assembly  110 . The door glass  170  may include a glass body  172  convexly protruding from the rear holder  140 . The glass body  172  may be formed of transparent glass such that a user may view the inner space of the cabinet  10 . 
     The door glass  170  may be arranged at a lower side of the second opening  180   a  in the door assembly  110 . The glass body  172  may include an introduction guide surface  172   a . The introduction guide surface  172   a  may be formed at an upper side of the door glass  170 , and may be slanted tilted downward in a rear direction. 
     Since the second opening  180   a  is arranged at an upper side of the door glass  170 , laundry or detergent introduced through the second opening  180   a  may be introduced into the drum  30  along the introduction guide surface  172   a . The introduction guide surface  172   a  may be slanted downward in the rear direction of the door assembly  110 , and the center part of the introduction guide surface  172   a  may be concave downward of lateral side parts of the introduction guide surface  172   a . The introduction guide surface  172   a  may allow laundry or detergent introduced through the second opening  180   a  to be easily put into the drum  30 . 
     The introduction guide surface  172   a  may be formed to extend from a connection guide surface  180   c  which will be described later. The introduction guide surface  172   a  may allow laundry or detergent guided by a connection guide surface  180   c  to be introduced into the cabinet  10 . 
     Although the introduction guide surface  172   a  disclosed in this embodiment is downwardly concave, the shape of the introduction guide surface  172   a  is not limited thereto. For example, the introduction guide surface  172   a  may be upwardly convex, or may be formed parallel to the rear end of the second opening  180   a  with the same height of the rear end of the second opening  180   a.    
     The door glass  170  may further include a glass flange  174  formed in a flange shape provided at the end of the glass body  172  such that the door glass  170  may be seated on the rear holder  140 . The glass flange  174  may be seated on a glass seating part  146  of the rear holder  140  such that the door glass  170  is not separated from the door assembly  110 . 
     The rear holder  140  may be provided at the rear of the front cover  130 . 
     The rear holder  140  may include a holder body  142  and a holder opening  144 . The holder opening  144  may be provided in the holder body  142  to form at least one part of the second opening  180   a . The holder body  142  may form at least one part of the rear surface of the door assembly  110 . 
     The door body  120  of the door assembly  110  may include the connection part  180 . The connection part  180  may form the second opening  180   a . The front end of the connection part  180  may be arranged at an inside of the cover opening  134  of the front cover  130 , and the rear end of the connection part  180  may be arranged at an inside of the holder opening  144  of the rear holder  140 . That is, the connection part  180  may be provided between the front cover  130  and the rear holder  140  so as to form the second opening  180   a  communicating inside with outside of the cabinet. 
     The connection part  180  may be provided in the form of a tube, both sides of which are opened. In detail, the second opening  180   a  may be formed at one side of the connection part  180 , and a discharge opening  180   b  facing the interior of the cabinet  10  may be formed at the other side of the connection part  180 . Laundry or detergent introduced through the second opening  180   a  may be delivered to the discharge opening  180   b  through a hollow part  180   d  formed in the connection part  180  such that the laundry or detergent may be introduced into the cabinet  10 . 
     The connection part  180  may include the connection guide surface  180   c . The connection guide surface  180   c  may be provided to form the bottom surface of the connection part  180 . The connection guide surface  180   c  may be formed between the second opening  180   a  and the discharge opening  180   b , such that laundry or detergent introduced through the second opening  180   a  may be guided to the inside of the cabinet  10  through the discharge opening  180   b.    
     The shape of the connection guide surface  180   c  is not limited thereto. For example, the connection guide surface  180   c  may be slanted downward in the direction from the front side to the rear side of the washing machine. 
     The connection part  180  may be provided to have the second opening  180   a  formed to be higher than the discharge opening  180   b . That is, the connection part  180  may be provided to have an inclination that is inclined downwardly to the rear side of the washing direction thereof. When laundry or detergent is introduced through the second opening  180   a , the laundry or detergent may be easily introduced into the cabinet  10  through the connection part  180  having a descending slope in the rear direction. 
     A front sealing part  182  may be provided at a front side of the connection part  180 , and a rear sealing part  184  may be provided at a rear side of the connection part  180 . 
     The front sealing part  182  may be provided at a front end of the connection part  180  so as to form a sealing structure by making contact with the auxiliary door  160 . A front sealing groove  183  to which the front sealing part  182  is fixed may be formed at the front end of the connection part  180 . 
     The front sealing part  182  may be formed adjacent to the second opening  180   a , so that when the second opening  180   a  is closed by the auxiliary door  160 , the front sealing part  182  is brought into contact with the auxiliary door  160 , to form a sealing structure. The front sealing part  182  may be formed along the circumference of the second opening  180   a.    
     Since the front sealing part  182  and the auxiliary door  160  form the sealing structure in the second opening  180   a , water leakage from the cabinet  10  may not occur when the auxiliary door  160  is closed. 
     The rear sealing part  184  may be provided at the rear of the connection part  180 , such that the sealing structure may be formed between the rear end of the connection part  180  and the holder opening  144 . A rear sealing groove  185  to which the rear sealing part  184  is fixed may be formed at the rear end of the connection part  180 . Since the holder opening  144  is arranged along the circumference of the discharge opening  180   b , the rear sealing groove  185  may be formed at an outside of the rear end of the connection part  180 . 
     The rear sealing part  184  may be formed adjacent to the discharge opening  180   b , such that the sealing structure may be formed between the holder opening  144  and the rear sealing part  184 . The rear sealing part  184  may be arranged adjacent to the discharge opening  180   b  along the circumference of the discharge opening  180   b.    
     The rear sealing part and the holder opening  144  may form the sealing structure in the discharge opening  180   b , such that occurrence of water leakage from the inside of the cabinet  10  to the inside of the door assembly  110  may be prevented. 
     Although the connection part  180  is disposed between the front cover  130  and the rear holder  140 , the arrangement and configuration of the connection part  180  are not limited thereto. For example, the connection part  180  may be integrally formed with the front cover  130  or the rear holder  140 . In addition, the connection part  180  may be integrally formed with the front cover  130  and the rear holder  140 . That is, the connection part  180  may be integrally formed with at least one of the front cover  130  and the rear holder  140 . 
     The rear holder  140  may include the glass seating part  146  in which the door glass  170  is seated. A rear glass hole  148  may be formed in the glass seating part  146  such that the glass body  172  passes through the rear glass hole  148 . In addition, the glass flange  174  may be seated in the rear of the glass seating part  146 , such that the door glass  170  may not be separated from the rear holder  140 . A seating sealing part  149  for preventing water leakage may be disposed between the glass seating part  146  and the glass flange  174 . 
     The rear holder  140  may include a door sealing unit  150 . 
     When the first opening  2   a  is closed by the door assembly  110 , the door sealing unit  150  may seal the interior of the cabinet  10  by making contact with the diaphragm  90 . The door sealing unit  150  may be formed in a ring shape corresponding to the ring-shaped diaphragm  90 . The door sealing unit  150  may be provided to make contact with the entire area of the circumference of the diaphragm  90 , to form the sealing structure for preventing wash water stored in the cabinet  10  from leaking outside through the first opening  2   a . Although the door sealing unit  150  according the embodiment is formed in a ring shape, the door sealing unit  150  may have a polygonal shape or an elliptical shape to match the diaphragm  90 . 
     The second opening  180   a  may be spaced inwardly apart from the door sealing unit  150 . The second opening  180   a  may be spaced apart from the door sealing unit  150  at an inside of the door sealing unit  150 , so that the second opening  180   a  is not interfered with the diaphragm  90  when the first opening  2   a  is closed by the door assembly  110 . Moreover, the holder opening  144  formed along the circumference of the second opening  180   a  may be spaced inwardly apart from the door sealing unit  150 . 
     The door glass  170  may be spaced inwardly apart from the door sealing unit  150 . The door glass  170  may be spaced apart from the door sealing unit  150  at an inside of the door sealing unit  150 , so that the door glass  170  is not interfered with the diaphragm  90  when the first opening  2   a  is closed by the door assembly  110 . In accordance with the embodiment of the present disclosure, the second opening  180   a  and the door glass  170  may be spaced apart from the door sealing unit  150  at an inside of the door sealing unit  150 . In detail, the rear end of the second opening  180   a  and the door glass  170  may be spaced apart from the door sealing unit  150  at an inside of the door sealing unit  150 . 
     The door sealing unit  150  may be formed of a material capable of forming the sealing structure by making contact the diaphragm  90 . For example, the door sealing unit  150  may include at least one of a glass material and an elastic member. In addition, the door sealing unit  150  may also be formed of a smooth-surface material. In addition, the door sealing unit  150  may be injection-molded together with the rear holder  140 . The material of the door sealing unit  150  is not limited thereto, and the door sealing unit  150  may also be formed of any material that forms a sealing structure together with the diaphragm  90  while making contact with the diaphragm  90 . 
     The second opening  180   a  may have a size smaller than that of the first opening  2   a . The first opening  2   a  may be provided in the cabinet  10  so as to be opened or closed by the door assembly  110 . The second opening  180   a  may be provided in the door assembly  110  so as to be opened or closed by the auxiliary door  160 . According to such a structure, even when the first opening  2   a  is closed by the door frame  120 , a user may put additional laundry or detergent into the cabinet  10  by opening the second opening  180   a.    
       FIG. 6  is a view illustrating an auxiliary door included in a door assembly which is opened according to an embodiment of the present disclosure. 
     Referring to  FIG. 6 , the door assembly  110  may include the auxiliary door  160  through which a user may put additional laundry or detergent into the drum  30  during the washing operation of the washing machine  100 . The auxiliary door  160  may be provided to be pivoted about the auxiliary door hinge part  164 . 
     Prior to beginning of the washing operation, a user may put laundry into the drum  30  by opening the door assembly  110 . After laundry and detergent are introduced into the drum  30 , a washing operation may be established and the washing machine  100  may perform the washing operation. When the washing operation starts, the door assembly  110  may be locked not to be opened at random. The locking of the door assembly  110  may be released when the washing operation is completed. In addition, when the washing operation is stopped by a user before the washing operation is complemented, the locking of the door assembly  110  may be released after wash water stored in the drum  30  is completely drained. 
     The washing machine according to the present disclosure includes the auxiliary door  160 , such that a user may put additional laundry or detergent into the drum  30  through the second opening  180   a  by opening the auxiliary door  160  during the washing operation. Since the user may put additional laundry or detergent into the drum by simply opening the auxiliary door  160  during the washing operation, so that usability of the washing machine  100  may be improved. 
     When detergent and wash water are supplied into the drum  30  and the washing operation is started, detergent bubbles may be generated in the drum  30 . As the washing operation proceeds, the top level of the detergent bubbles may gradually ascend to the upper side of the interior of the drum  30 . Therefore, if a user opens the auxiliary door  160  after the washing operation is performed, detergent bubbles contained in the drum  30  may flow outside the washing machine  100 . If detergent bubbles flow outside the washing machine  100 , the surrounding area of the washing machine  100  becomes messy and a safety accident may occur. 
     In accordance with one embodiment of the present disclosure, the auxiliary door glass  166  may be formed to protrude from the rear part of the auxiliary door body  162  of the auxiliary door  160 . Even when wash water and detergent are supplied into the drum  30  and the washing operation is started, detergent bubbles in the drum  30  may reach only the outside of the bottom surface  166   b  of the auxiliary door glass  166  due to the auxiliary door glass  166 . 
     The auxiliary door glass  166  protruding backward from the auxiliary door body  162  allows the second opening  180   a  to be spaced apart from the detergent bubbles contained in the drum  30  by a predetermined distance corresponding to the length of the side surface part  166   a  protruding backward from the auxiliary door body  162 . Therefore, even when the auxiliary door  160  is opened by a user during a washing operation, detergent bubbles in the drum  30  are prevented from flowing outside through the second opening  180   a.    
     The sealing member  168  may be provided at the outside of the auxiliary door glass  166 , such that the space between the connection part  180  located outside the auxiliary door glass  166  and the auxiliary door glass  166  may be sealed. Even if the washing operation is performed and wash water is supplied into the drum  30 , the wash water and detergent bubbles are not introduced into the space between the auxiliary door glass  166  and the connection part  180 , such that the wash water or the detergent bubbles may not adhere to the outer surface of the auxiliary door glass  166 . Therefore, when the auxiliary door  160  is opened by the user during the washing operation, the sealing member  168  may prevent water or detergent bubbles from sticking to the outer surface of the auxiliary door glass  166  and flowing outside the washing machine  100 . 
       FIG. 7  is a view illustrating a door assembly according to another embodiment of the present disclosure.  FIG. 8  is a view illustrating an auxiliary door included in a door assembly which is opened according to another embodiment of the present disclosure. 
     Referring to  FIGS. 7 and 8 , the door assembly  110  according to another embodiment may include a cap  186  to selectively open the connection part  180 . The cap  186  may be positioned in the connection part  180  or at the rear of the connection part  180  while being spaced apart from the auxiliary door body  162  by a predetermined distance. 
     The remaining constituent elements other than the cap  186  located at the rear of the connection part  180  may be similar to the concept of the door assembly  110  shown in  FIGS. 3 to 5 . However, the auxiliary door glass  166  may not be located at the rear of the auxiliary door body  162  of the door assembly  110  illustrated in  FIGS. 7 and 8 . 
     The cap  186  may rotate about a rotation shaft  187 . The mounting part  189  to which the rotation shaft  187  is mounted may be arranged at one side of the connection part  180 . The mounting part  189  may protrude inward from the rear of the connection part  180 . 
     An elastic member  188  for providing elastic force to the cap  186  may be mounted to the rotation shaft  187 . The elastic member  188  may provide elastic force such that the cap  186  closes the connection part  180  so far as no external force exists. The cap  186  is located at the rear of the connection part  180  so that the rear part of the connection part  180  may be selectively opened. For example, the cap  186  may selectively open the rear end of the connection part  180 . 
     Since the cap  186  is located at the rear part of the connection part  180  such that the rear part of the connection part is closed, wash water or detergent bubbles in the drum  30  may not leak to the connection part  180  even if the washing operation is performed. That is, the cap  186  prevents wash water or detergent bubbles in the drum  30  from being introduced into the space formed by the auxiliary door body  162 , the connection part  180 , and the cap  186 . 
     The cap  186  may be formed of a ductile material such as rubber or silicon. Accordingly, the quality of sealing between the cap  186  and the connection part  180  is improved, such that wash water or detergent bubbles may not leak into the space formed by the auxiliary door body  162 , the connection part  180 , and the cap  186 . 
     The cap  186  may be formed of a rigid material, and the sealing member may be arranged around an outer circumference of the cap  186  which makes contact with the connection part  180 . For example, the cap  186  may be formed of a metal or plastic material, and the sealing member may be mounted to an outer circumferential surface of the cap  186 . Although the sealing member is illustrated as being arranged around the outer circumference of the cap  186 , the installation position of the sealing member is not limited thereto as long as the space between the cap  186  and the connection part  180  is sealed by the sealing member. 
     Since the connection part  180  is closed by the cap  186 , wash water or detergent bubbles in the drum  30  may not be introduced to the inside of the connection part  180 . Therefore, even if the auxiliary door  160  is opened by a user during a washing operation, the connection part  180  is in a state of being closed by the cap  186 , and therefore, wash water or detergent bubbles in the drum  30  do not flow to the outside of the washing machine  100  through the connection part  180 . 
     The cap  186  may rotate about the rotation shaft  187  by an external force. The cap  186  may rotate about the rotation shaft  187  so as to have one side thereof directed to the rear part at which the drum  30  is located. As described above, the cap  186  rotates about the rotation shaft  187  by an external force, such that the rear side of the connection part  180  may be opened. 
     When the user desires to additionally put laundry or detergent into the drum after the auxiliary door  160  is open, the user may open the connection part  180  by pushing the cap  186 . That is, the user may open the connection part  180  by pushing the cap  186 , and may additionally put laundry or detergent into the drum  30  through the opened connection part  180 . 
     Since the cap  186  is spaced apart from the rear side of the auxiliary door  160  by a predetermined distance, detergent bubbles in the drum  30  may be prevented from easily flowing to the outside the washing machine  100  through the second opening  180   a . In addition, since the connection part  180  is closed by the cap  186 , water or detergent bubbles may be prevented from sticking to the rear surface of the auxiliary door body  162 . Therefore, when the auxiliary door  160  is opened, water or detergent bubbles attached to the rear surface of the auxiliary door body  162  may be prevented from flowing to the outside of the washing machine  100 . 
     Not only the auxiliary door glass  166  located at the rear of the auxiliary door body  162  as illustrated in  FIGS. 3 to 6 , but also the cap  186  covering the connection part  180  while being spaced apart from the auxiliary door body  162  by a predetermined distance as illustrated in  FIGS. 7 and 8  may be spaced apart from the rear surface of the auxiliary door body  162  by a predetermined distance so as to prevent detergent bubbles in the drum  30  from being introduced to the front of the washing machine. Accordingly, the auxiliary door glass  166  and the cap  186  may be referred to as an interference part. A predetermined space is formed in the rear of the auxiliary door  160  by the interference part, such that wash water and detergent bubbles in the drum  30  may be prevented from being introduced to the front of the washing machine. 
       FIG. 9  is a view illustrating a door assembly according to still another embodiment of the present disclosure.  FIG. 10  is a view illustrating an auxiliary door included in a door assembly which is opened according to still another embodiment of the present disclosure. 
     Referring to  FIGS. 9 and 10 , the front sealing part  182  included in the door assembly  110  according to still another embodiment may partially cover the second opening  180   a . The front sealing part  182  is formed adjacent to the second opening  180   a . When the auxiliary door  160  is closed, the auxiliary door  160  is brought into contact with the front sealing part  182 , such that the sealing structure is formed. 
     The front sealing part  182  may be arranged along the circumference of the second opening  180   a . The front sealing part  182  may protrude upward by a predetermined height (h 2 ) so as to cover a portion of the lower part of the second opening  180   a . When the vertical height of the second opening  180   a  is denoted by h 1 , the upward protruding length of the portion of the lower part of the front sealing part  182  partially covering the second opening  180   a  is denoted by h 2 . 
     In the second opening  180   a , a part corresponding to height (h 3 ) obtained when the height (h 2 ) of the front sealing part  182  is subtracted from the height (h 1 ) of the second opening  180   a  may be selectively opened by the auxiliary door  160 . When the auxiliary door  160  is opened, the user may additionally put laundry or detergent into the drum  30  through the part corresponding to the height (h 3 ) of the second opening  180   a.    
     Since a portion of the lower part of the second opening  180   a  is covered by the front sealing part  182 , detergent bubbles in the drum  30  are prevented from easily flowing to the outside of the washing machine  100 . 
     The front sealing part  182  may be formed of deformable material such as rubber or silicon. When a portion of the lower part of the second opening  180   a  is covered by the front sealing part  182 , the user desires to put laundry larger than the upper portion of the second opening  180   a  which is not covered by the front sealing part  182  into the drum  30 , the front sealing part  182  may be deformed by a force pushing the front sealing part  182 , such that large-sized laundry may be easily introduced into the drum  30 . 
     The structure of the front sealing part  182  illustrated in  FIGS. 9 and 10 , the structure of the auxiliary door glass  166  illustrated in  FIGS. 3 to 6 , and the structure of the cap illustrated in  FIGS. 7 and 8  may be used individually or as a combination of two or more embodiments described above. 
     As described above, the washing machine  100  according to the embodiments may prevent detergent bubbles in the drum  30  from flowing to the outside of the washing machine  100  when the auxiliary door  160  is opened, the surrounding area of the washing machine  100  may be kept clean in sanitary condition, and safety accident due to detergent bubbles and wash water flowing to the outside of the washing machine  100  may be prevented. 
     As is apparent from the above description, the washing machine according to the embodiments can prevent bubbles in the drum from flowing to the outside when the auxiliary door is opened during the washing process, thereby preventing consumer complaints and safety accidents. 
     Although a few embodiments of the present disclosure have been shown and described, it would 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 claims and their equivalents.