Patent Publication Number: US-2006000244-A1

Title: Drum washing machine

Description:
This application claims the benefit of the Korean Patent Application No. 20074-39601, filed on Jun. 1, 2004, which is hereby incorporated by reference as if fully set forth herein.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a drum washing machine, and more particularly, to a drum washing machine including a tub, and a drum rotatably mounted in the tub, wherein the mounting structure for balance weights mounted to a front wall of the tube for weight balance, taking into consideration the weight of a motor mounted to a rear wall of the tub, is improved.  
      2. Discussion of the Related Art  
      Generally, drum washing machines wash laundry, utilizing friction generated between the laundry and a drum, which is horizontally arranged, and is rotated by a drive force of a motor, under the condition in which detergent and washing water are placed into the drum, together with the laundry. Such a drum washing machine has a washing effect capable of washing laundry using beating and rubbing actions without causing damage and entanglement of the laundry.  
       FIG. 1  is a sectional view illustrating a conventional drum washing machine. Referring to  FIG. 1 , the conventional drum washing machine includes a cabinet  1 , a tub  3  arranged in the cabinet  1  to contain washing water, and a drum  4  rotatably arranged in the tub  3  to carry out a laundry washing function. A door  9  is hingably mounted to an opened front wall of the cabinet  1  by means of a door hinge assembly such that the door  9  is openable to allow laundry to be put into the interior of the drum washing machine through the front wall of the cabinet  1 .  
      The tub  3  includes a tub body  3   b , and a tub cover  3   a  adapted to cover the front side of the tub body  3   b , that is, to constitute a front wall of the tub body  3   b . A motor  8  is rotatably mounted to a rear wall of the tub  3 . The motor  8  includes a rotating shaft axially connected to the drum  4 , so as to rotate the drum  4 . Dampers  6  and springs  7  are mounted to the top and bottom sides of the tub  3 , in order to damp vibrations generated during a spin drying cycle of the drum washing machine, respectively.  
      Since the motor  8 , which has a substantial weight, is mounted to the rear wall of the tub  3 , the weight of the tub  3  is rearwardly off balance. As a result, the drum  4  cannot be smoothly rotated during operation of the drum washing machine. In order to eliminate such a weight unbalance of the tub  3 , balance weights  5 , each of which has a predetermined weight, are mounted to the front wall of the tub  3 , that is, the tub cover  3   a , as shown in  FIGS. 1 and 2 .  
      Generally, the balance weights  5  may be formed by pouring a cement material into a mold or a cavity formed in a hollow plastic molded product, and curing the cement material. Alternatively, the balance weights  5  may be formed using a casting method. The balance weights  5  are mounted to the front wall of the tub  3  by means of a plurality of bolts  5   a.    
      Conventionally, the balance weights  5  are laterally symmetrically arranged on a lower portion of the front wall of the tub  3 . In this case, however, during operation of the drum washing machine, the tub  3  not only vibrates axially, but also vibrates vertically while swinging axially about an axially central portion of the tub  3  where the dampers  6  and springs  7  are mounted. In particular, the swing and vibration of the tub  3  increase as the operation of the drum washing machine is continued.  
      As a result, where the balance weights  5  are mounted to the tub  3  by means of the bolts  5   a , as in the above-mentioned case, cracks may be generated at regions around bolt holes, through which the bolts  5   a  are fastened. Furthermore, when the axial swing and vertical vibration of the tub  3  increase, the front portion of the drum  4  may strike the front wall of the tub  3 , that is, the tub cover  3   a . In this case, the tub cover  3   a  may be damaged because the tub cover  3   a  is made of a plastic material.  
     SUMMARY OF THE INVENTION  
      Accordingly, the present invention is directed to a drum washing machine that substantially obviates one or more problems due to limitations and disadvantages of the related art.  
      An object of the present invention is to provide a drum washing machine which includes a balance weight mounting structure capable of reducing vibration generated at a tub of the drum washing machine, thereby being capable of preventing the tub from being damaged at regions where bolts are fastened, during operation of the drum washing machine, while preventing the front wall of the tub from being damaged due to contact between the tub and a drum arranged in the tub.  
      Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
      To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a drum washing machine comprises: a cabinet which forms an outer appearance of the drum washing machine; a tub disposed in the cabinet, the tub being balanced in weight between positions opposing to each other on a front wall of the tub with respect to a center of the front wall of the tub; and a drum rotatably disposed in the tub, and adapted to perform a washing function in accordance with a rotation of a motor attached to a rear wall of the tub.  
      The drum washing machine may further comprise balance weights mounted to the front wall of the tub, and adapted to cause the tub to be balanced in weight between positions opposing to each other on the front wall of the tub with respect to the center of the front wall of the tub.  
      The balance weights may have a total weight equal to a weight of the motor mounted to the rear wall of the tub.  
      The balance weights may be symmetrically arranged with respect to a first central line extending vertically through the center of the front wall of the tub along the front wall of the tub.  
      The balance weights may be symmetrically arranged with respect to a second central line extending in perpendicular to the first central line through the center of the front wall of the tub along the front wall of the tub.  
      The balance weights may be symmetrically arranged with respect to a third central line extending diagonally through the center of the front wall of the tub along the front wall of the tub.  
      The balance weights may be symmetrically arranged with respect to a fourth central line extending in perpendicular to the third central line through the center of the front wall of the tub along the front wall of the tub.  
      In another aspect of the present invention, a drum washing machine comprises: a cabinet which forms an outer appearance of the drum washing machine; a tub disposed in the cabinet, the tub being balanced in weight between positions opposing to each other on the front wall of the tub with respect to a center of a front wall of the tub; a drum rotatably disposed in the tub, and adapted to perform a washing function in accordance with a rotation of a motor attached to a rear wall of the tub; and a suction duct and an exhaust duct respectively connected to the front and rear walls of the tub, the suction duct having a heater and a blowing fan.  
      The drum washing machine may further comprise balance weights mounted to the front wall of the tub, and adapted to cause the tub to be balanced in weight between positions opposing to each other on the front wall of the tub with respect to the center of the front wall of the tub.  
      The balance weights may have a total weight equal to a weight of the motor mounted to the rear wall of the tub.  
      The balance weights may be symmetrically arranged with respect to a first central line extending vertically through the center of the front wall of the tub along the front wall of the tub.  
      The balance weights may be symmetrically arranged with respect to a second central line extending in perpendicular to the first central line through the center of the front wall of the tub along the front wall of the tub.  
      The balance weights may be symmetrically arranged with respect to a third central line extending diagonally through the center of the front wall of the tub along the front wall of the tub.  
      The balance weights may be symmetrically arranged with respect to a fourth central line extending in perpendicular to the third central line through the center of the front wall of the tub along the front wall of the tub.  
      In another aspect of the present invention, a drum washing machine comprises: a cabinet which forms an outer appearance of the drum washing machine; a tub disposed in the cabinet to contain washing water; a drum rotatably disposed in the tub to perform a washing function in accordance with a rotation of a motor attached to a rear wall of the tub; and a pair of balance weights mounted to a front wall of the tub, and adapted to cause the tub to be balanced in weight between positions opposing to each other on the front wall of the tub with respect to the center of the front wall of the tub.  
      In another aspect of the present invention, a drum washing machine comprises: a cabinet which forms an outer appearance of the drum washing machine; a tub disposed in the cabinet to contain washing water; a drum rotatably disposed in the tub to perform a washing function in accordance with a rotation of a motor attached to a rear wall of the tub; a pair of balance weights mounted to a front wall of the tub, and adapted to cause the tub to be balanced in weight between positions opposing to each other on the front wall of the tub with respect to the center of the front wall of the tub; and a suction duct and an exhaust duct respectively connected to the front and rear walls of the tub, the suction duct having a heater and a blowing fan.  
      It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:  
       FIG. 1  is a sectional view illustrating a conventional drum washing machine;  
       FIG. 2  is a front view illustrating a conventional balance weight mounting structure for mounting balance weights in the conventional drum washing machine;  
       FIG. 3  is a sectional view schematically illustrating a configuration of a drum washing machine to which first and second embodiments of the present invention are applied;  
       FIG. 4  is a front view illustrating a balance weight mounting structure for mounting balance weights in the drum washing machine in accordance with the first embodiment of the present invention;  
       FIG. 5  is a front view illustrating a balance weight mounting structure for mounting balance weights in the drum washing machine in accordance with the second embodiment of the present invention; and  
       FIG. 6  is an exploded perspective view illustrating a balance weight mounting structure for mounting balance weights in a drum washing machine with a drying function in accordance with a third embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
       FIG. 3  schematically illustrates a configuration of a drum washing machine to which first and second embodiments of the present invention are applied.  FIG. 4  illustrates a balance weight mounting structure for mounting balance weights in the drum washing machine in accordance with the first embodiment of the present invention.  FIG. 5  illustrates a balance weight mounting structure for mounting balance weights in the drum washing machine in accordance with the second embodiment of the present invention.  
      Referring to  FIG. 3 , the drum washing machine, to which the first and second embodiments of the present invention are applied, includes a cabinet  100 , a tub  30  arranged in the cabinet  100  to contain washing water, and a drum  40  rotatably arranged in the tub  30  to carry out a laundry washing function.  
      A door  90  is hingably mounted to an opened front wall of the cabinet  100  by means of a hinge assembly such that the door  90  is openable to allow laundry to be put into the interior of the drum washing machine through the front wall of the cabinet  100 . The tub  30  includes a tub body  30   b , and a tub cover  30   a  attached to the front side of the tub body  30   b  to constitute a front wall of the tub body  30   b.    
      A motor  80  is rotatably mounted to a rear wall of the tub  30 . The motor  80  is axially connected with the drum  40  to rotate the drum  40 . Dampers  60  and springs  70  are mounted to the top and bottom sides of the tub  30 , in order to damp vibrations generated during a spin drying cycle of the drum washing machine, respectively.  
      Since the motor  80 , which has a substantial weight, is mounted to the rear wall of the tub  30 , the weight of the tub  30  is rearwardly off balance. As a result, the drum  40  cannot be smoothly rotated during operation of the drum washing machine. In order to eliminate such a weight unbalance of the tub  30 , balance weights  50 , each of which has a predetermined weight, are mounted to the front wall of the tub  30 , that is, the tub cover  30   a.    
      Generally, the balance weights  50  may be formed by pouring a cement material into a mold or a cavity formed in a hollow plastic molded product, and curing the cement material. Alternatively, the balance weights  50  may be formed using a casting method. The balance weights  50  are mounted to the front wall of the tub  30  by means of a plurality of bolts  50   a.    
       FIG. 4  illustrates a balance weight mounting structure for mounting balance weights in a drum washing machine in accordance with a first embodiment of the present invention. In this case, the drum washing machine includes a cabinet  100 , which forms an outer appearance of the drum washing machine, a tub  30  arranged in the cabinet  100  to contain washing water, and a drum  40  rotatably arranged in the tub  30  to carry out a laundry washing function in accordance with rotation of a motor  80  mounted to a rear wall of the tub  30 .  
      Balance weights  50  are mounted to a front wall of the tub  30  such that the balance weights  50  are symmetrical with respect to a first center line I-I extending vertically through the center c of the front wall of the tub  30  along the front wall of the tub  30 . The balance weights  50  are also symmetrical with respect to a second center line II-II extending through the center c of the front wall of the tub  30  in perpendicular to the first center line I-I along the front wall of the tub  30 . Accordingly, the front wall of the tub  30  mounted with the balance weights  50  is balanced in weight between positions opposing to each other with respect to the center c of the front wall of the tub  30 . In this case, the balance weights  50  may be typically mounted to the tub cover  30   a , which constitutes the front wall of the tub  30 , as shown in  FIG. 3 .  
      Although  FIG. 4  illustrates a structure in which two balance weights are symmetrically arranged, an increased number of balance weights may be symmetrically arranged.  
      Meanwhile,  FIG. 5  illustrates a balance weight mounting structure for mounting balance weights in a drum washing machine in accordance with a second embodiment of the present invention. In this case, balance weights  50  are mounted to the front wall of the tub  30  such that the balance weights  50  are symmetrical with respect to a third center line III-III extending diagonally through the center c of the front wall of the tub  30  along the front wall of the tub  30 . The balance weights  50  are also symmetrical with respect to a fourth center line IV-IV extending through the center c of the front wall of the tub  30  in perpendicular to the third center line III-III along the front wall of the tub  30 .  
      In both the first and second embodiments illustrated in  FIGS. 4 and 5 , the weight of each balance weight  50  is determined, taking into consideration the weight of the motor  80  mounted to the rear wall of the tub  30 . In either embodiment, it is preferred that the total weight of the balance weights  50  be equal to the weight of the motor  80 .  
      Hereinafter, functions and effects according to the above-described first and second embodiments of the present invention will be described.  
      The balance weights  50  are mounted to the peripheral portion of the front wall of the tub  30  such that balance is maintained between positions opposing to each other with respect to the center c of the front wall of the tub  30 , thereby causing the tub  30  to have the same weight distribution at portions of the tub  30  opposing to each other with respect to the center c of the front wall of the tub  30 .  
      That is, in accordance with the present invention, the center of gravity of the front wall of the tub  30  is shifted toward the center c of the front wall of the tub  30  from a lower position where the center of gravity of the front tub wall is positioned in the conventional case illustrated in  FIG. 2 . Accordingly, the vertical and horizontal vibration of the tub  30  generated during the washing and spin drying operations of the drum washing machine is greatly reduced, as compared to the conventional case.  
      Thus, it is possible to prevent cracks from being generated due to the vibration of the tub  30  during operation of the drum washing machine at regions where the bolts  50   a  are fastened. Also, it is possible to prevent the tub  30  from coming into contact with the drum  40 , and thus, to enable the drum washing machine to operate more stably.  
      Meanwhile, although the first and second embodiments of the present invention have been illustrated and described in conjunction with a general drum washing machine, the balance weight mounting structure of the present invention is applicable to a drum washing machine with a drying function, demand for which has recently increased. Referring to  FIG. 6 , a third embodiment of the present invention is illustrated in which the balance weight mounting structure of the present invention is applied to a drum washing machine with a drying function.  
      As shown in  FIG. 6 , the drum washing machine applied to the third embodiment of the present invention includes a cabinet (not shown), which forms an outer appearance of the drum washing machine, a tub  30  arranged in the cabinet to contain washing water, and a drum  40  rotatably arranged in the tub  30  to carry out a laundry washing function in accordance with rotation of a motor (not shown) mounted to a rear wall of the tub  30 .  
      A suction duct  10  adapted to suck air into the drum  40  and an exhaust duct  20  adapted to exhaust air from the drum  40  are mounted to the tub  30 . An air inlet  31  is formed at the tub  30  in order to communicate the tub  30  with the suction duct  10 . Balance weights  50  are mounted to a front wall of the tub  30  in such a manner that the front wall of the tub  30  is balanced in weight between positions opposing to each other with respect to the center of the front wall of the tub  30 .  
      As described above, this drum washing includes the suction duct  10  and exhaust duct  20  for sucking and exhausting air into and from the drum  40 , respectively, for the drying function. For this reason, the balance weights  50  are mounted to the front wall of the tub  30  at positions other than the position of the air inlet  31  formed at an upper portion of the front wall of the tub  30  to communicate the tub  30  with the suction duct  10 .  
      Although not shown, the balance weights  50  are arranged at positions other than the position of the air inlet  31  such that the front wall of the tub  30  is balanced in weight between positions opposing to each other with respect to the center of the front wall of the tub  30 , similarly to the first or second embodiment.  
      That is, similarly to the first embodiment, the balance weights  50  are arranged symmetrically with respect to a first center line extending vertically through the center of the front wall of the tub  30  along the front wall of the tub  30 . The balance weights  50  are also symmetrical with respect to a second center line extending through the center of the front wall of the tub  30  in perpendicular to the first center line along the front wall of the tub  30 .  
      Alternately, similarly to the second embodiment, the balance weights  50  may be arranged symmetrically with respect to a third center line extending diagonally through the center of the front wall of the tub  30  along the front wall of the tub  30 . In this case, the balance weights  50  are also symmetrical with respect to a fourth center line extending through the center of the front wall of the tub  30  in perpendicular to the third center line along the front wall of the tub  30 .  
      In the third embodiment, the weight of each balance weight  50  is determined, taking into consideration not only the weight of the motor, but also the weights of the suction duct  10  and exhaust duct  20 . In this embodiment, it is preferred that the total weight of the balance weights  50  mounted to the front wall of the tub  30  be equal to the weight of the motor mounted to the rear wall of the tub  30 .  
      Hereinafter, functions and effects according to the above-described third embodiment of the present invention will be described. Similarly to the first and second embodiments, the balance weights  50  are mounted to the peripheral portion of the front wall of the tub  30  such that the front wall of the tub  30  has a structure symmetrical with respect to the center of the front wall of the tub  30 . Accordingly, balance is maintained between positions of the front wall of the tub  30  opposing to each other with respect to the center of the front wall of the tub  30 .  
      That is, in accordance with the present invention, the center of gravity of the front wall of the tub  30  is shifted toward the center of the front wall of the tub  30  from a lower position where the center of gravity of the front tub wall is positioned in the conventional case. Accordingly, the vertical vibration of the tub  30  generated along with swing of the tub  30  about an approximately central portion of the tub  30  during operation of the drum washing machine is greatly reduced, as compared to the conventional case.  
      Thus, it is possible to prevent cracks from being generated at regions where the bolts are fastened. Also, it is possible to prevent the tub  30  from coming into contact with the drum  40 , and thus, to enable the drum washing machine to operate more stably.  
      As apparent from the above description, in accordance with the present invention, it is possible to perform a washing operation through a more stable structure, as compared to the conventional case. That is, the drum washing machine, in which the balance weights according to one of the above-described embodiments of the present invention are installed, can greatly reduce vibration generated at the tub, thereby preventing cracks from being generated at regions where bolts for mounting the balance weights are fastened. In addition, it is possible to prevent contact between the tub and the drum, and thus, to prevent generation of noise caused by the contact between the tub and the drum.  
      It will be apparent to those skilled in the art that various modifications and varitations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention covers the modifications and varitations of this invention provided they come within the scope of the appended claims and their equivalents.