Patent Publication Number: US-2006000245-A1

Title: Balance weight for washing machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of Korean Application No. P2004-50315, filed on Jun. 30, 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 washing machine, and more particularly, to a balance weight which is mounted on a tub of the washing machine for balancing the tub and reducing vibration of the tub.  
      2. Discussion of the Related Art  
      Washing machine is a representative home appliance for washing laundry using detergent and water. The washing machine is generally classified into two types, i.e., a top loading type and a front loading type based on the location of an opening for receiving the laundry.  
      The top loading type washing machine generally comprises a vertical tub for accommodating the laundry, a pulsater rotating in the tub and washing the laundry, and a lid provided on an upper surface of the washing machine for opening and closing the tub.  
      The front loading type washing machine generally comprises a horizontal tub for accommodating washing water, a horizontal drum provided in the tub for accommodating the laundry, lifters provided on an inner surface of the drum for lifting and dropping the laundry when the drum is rotated for washing, rinsing or dehydrating the laundry, and a door provided on a front surface of the washing machine for opening and closing the drum.  
      In the front loading type washing machine, a motor for driving the drum is mounted on a rear surface of the tub. Due to the motor, a rear portion of the tub is heavier than a front portion of the tube, thus, a balance weight is generally mounted on the front portion of the tub for balancing the tub. The balance weight provided on the front portion of the tub also makes the tub heavy. Thus, the balance weight not only balances the tube, but also reduces the vibration of the tub generated when the washing machine is operated.  
      The balance weight is generally made of heavy metal, cement, or concrete by casting. Since enough time is necessary for material of the balance weight to be solidified, it takes long time for manufacturer to produce the balance weight by casting. In addition, it is hard to change the weight of the contemporary balance weight. Thus, it is hard to adjust the weight of the balance weight in order to reflect errors occurred when the washing machine is assembled.  
     SUMMARY OF THE INVENTION  
      Accordingly, the present invention is directed to a balance weight that substantially obviates one or more problems due to limitations and disadvantages of the related art.  
      An object of the present invention is to improve the structure of the balance weight for quick and easy assembly.  
      Another object of the present invention is to improve the structure of the balance weight for easy adjustment of the weight of the balance weight according to errors occurred during assembling process.  
      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 balance weight for washing machine comprises a plurality of weight plates piled up, and at least one coupling member securing the weight plates to a tub of the washing machine.  
      Each of the weight plates may be configured to be bent in order to have a shape corresponding to a circumferential surface of the tub.  
      Each of the weight plates may comprise at least one hole in which the coupling member passes through. The hole may be configured to have an elliptical shape. Or, the hole may be configured to be elongated along with a direction substantially perpendicular to a bent line of the weight plate.  
      Each of the weight plates may comprise at least one first hole receiving the coupling member binding the weight plates into a body, and at least one second hole receiving the coupling member fitting the weight plates to the tub.  
      The coupling member may comprise at least one first member binding the weight plates into a body, and at least one second member fitting the weight plates bound by the first member to the tub. The first member may comprise a bolt and a nut or comprise a rivet.  
      The tub may comprise at least one boss provided on an outer surface of the tub and receiving the coupling member. The tub may further comprise at least one supplementary rib connected with the boss and the outer surface of the tub for reinforcing the strength of the boss. The weight plates may comprise at least one boss hole receiving the boss therein. The boss hole may be configured to be formed on partial weight plates located lower position.  
      In another aspect of the present invention, a balance weight for washing machine comprises a plurality of weight plates separably plied up, at least one first member binding the weight plates into a body and separable from the weight plates, at least one second member fitting the bound weight plates onto the tub and separable from the tub, and at least one boss provided on the tub and allowing the boss to be fitted thereto.  
      In another aspect of the present invention, a balance weight for washing machine comprises a case, a tub provided in the case and holding washing water therein, a rotatable drum provided in the tub and accommodating laundry therein, a motor driving the drum, a plurality of weight plates separably plied up, at least one first member binding the weight plates into a body, and at least one second member securing the weight plates bound by the first member to the tub.  
      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 of the invention and together with the description serve to explain the principle of the invention. In the drawings;  
       FIG. 1  illustrates a cross sectional view of the washing machine according to the present invention;  
       FIG. 2  illustrates an exploded perspective view of weight plates of the balance weight according to the present invention;  
       FIG. 3  illustrates a perspective view of the weight plates and coupling members for fitting the weight plates to the tub;  
       FIG. 4  illustrates a cross sectional view of the weight plates and the coupling members in  FIG. 3 ; and  
       FIG. 5  illustrates a perspective view of the balance weight mounted on the tub. 
    
    
     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.  
      As shown in  FIG. 1 , a horizontal tub  10  for holding washing water therein is provided in a case  1  of the washing machine. The tub  10  is suspended in the case  1  by a plurality of spring  34  and damper  32  respectively provided between the case  1  and the tub  10 . The spring  34  and the damper  32  not only suspend the tub  10  in the case  1 , but also reduce the vibration of the tub  10  generated during the operation of the washing machine.  
      An opening  11  is provided on a front portion of the tub  10 , and an opening  2  is provided on a front surface of the case  1 . The openings  2  and  11  are communicated with each other and facing each other. A door  3  is coupled to the front surface of the case  1  by a hinge, and opens and closes the openings  2  and  11 . And, a gasket  15  is provided between the opening  11  of the tub  10  and the door  3  for preventing a leakage of the washing water stored in the tub  10 .  
      A water supply hole (not shown in  FIG. 1 ) is provided on an upper portion of the tub  10 . The water supply hole communicates with a water supply hose  8  through a detergent box  7 . Thus, the washing water is supplied into the tub  10  with detergent stored in the detergent box  7 . A drain  16  for draining the washing water in the tub  10  is provided on a lower portion of the tub  10 . The drain  16  communicates with drain hose  18  through a drain pump  17 . Thus, contaminated washing water in the tub  10  is drained out through the drain  16  and drain hose  18  when the drain pump  17  is operated.  
      A rotatable horizontal drum  12  for accommodating laundry therein is provided in the tub  10 . A plurality of apertures are provided on a circumference of the drum  12 , thus, the washing water in the tub  10  can be introduced into the drum  12  through the apertures. A plurality of lifters  13  are projected from an inner surface of the drum  12 . The lifters  13  lifts and drops the laundry in the drum  12  during a washing process, a rinsing process, and a dry process in order to improve performance of the processes.  
      The drum  12  is directly driven by a motor  20 . As shown in  FIG. 1 . The motor  20  is mounted on an outer surface of the tub  10 , and a shaft  22  of the motor  20  is connected to a rear of the drum  12  through the tub  10 . A balance weight  100  is provided on an upper front portion of the tub  10  as shown in  FIG. 1 .  
      The balance weight  100  weighs approximately at similar to the motor  20  do in order to balance the tub  10 . In addition, the balance weight  100  suppresses the generation of the vibration of the tub  10  during the operation of the washing machine and reduces generated vibration of the tub  10 .  FIG. 2  through  FIG. 4  illustrates the structure of the balance weight  100  according to the present invention in detail. Thus, detailed structure of the balance weight  100  according to the present invention will be described in the following with reference to the drawings.  
      As shown in  FIG. 2 , the balance weight  100  comprises a plurality of weight plates  110  piled up, and at least one coupling member securing the weight plates  110  to the tub  10 . Since the tub  10  has a cylindrical shape, it is preferable that the weight plates  110  are bent in order to have a shape corresponding to a circumferential surface of the tub  10 . The weight plates  110 , for example, have two bent lines in order that the weight plates  110  have two plane surface having different height level and slope between the two plane surface as shown in  FIG. 2 .  
      In this case, a first plane surface positioned in high level is fitted to an upper center portion of the tub  10 , and a second plane surface positioned in low level is fitted to a side portion of the tub  10 , as shown in  FIG. 5 . However, the present invention is not limited in that case. For another example, the weight plates  110  can be bent in order that the weight plates  110  have a curved portion corresponding to the outer surface of the tub  10 . Further, it would be possible that the weight plates  110  are bent as the other shape according to the location to be installed and the structure of the installation.  
      The weight plates  110  are separably piled up, and coupled one another by a first member  140  before the weight plates  110  are secured to the tub  10 . The first member  140  binds the weight plates  110  into one body for securing the weight plates  110  from disassembly of the weight plates  110 , and thereby the weight plates  110  are not separated from one another.  
      The weight plates  110  includes at least one first hole  120 . The first hole  120  is provided on each edge portion of the weight plates  110 . All of the first hole  120  communicates with one another when the weight plates  110  are piled up. And, the first member  140  passes through the first hole  120  and bind all of the weight plates  110 . The first member  140  comprises a bolt and a nut, or comprises a rivet. In case the first member  140  comprises the bolt and the nut, the first member  140  is liable to be separated from the weight plates  110 , if necessary.  
      Although each of the first hole  120  is provided on the same location of each weight plate  110 , all of the first hole  120  fail to communicate with one another after all of the weight plates  110  are piled up, if the weight plates  110  are bent or piled up inaccurately. In this case, it is hard for the first member  140  to be inserted into and to pass through the first hole  120 . Thus, the first hole  120  has an elliptical shape as shown in  FIGS. 2 and 3  in order that the first member  140  is inserted into the first hole  120  with ease.  
      In this case, the first hole  120  is configured to be elongated along with a direction substantially perpendicular to the bent line of the weight plates  110 . Or, the elliptical first hole  120  is configured to be elongated along with a circumferential direction of the tub  10 . If the first hole  120  has the elliptical shape as mentioned above, the first member  140  is liable to be inserted into and to pass through the first hole  120  with ease even if all of the first hole  120  are not aligned accurately.  
      There is no harm if the weight plates  110  are made of new and fresh plates. However, it is preferable that the weight plates  110  are made of used plate, especially waste plate cut away from large plate when the washing machine is fabricated. And then, the cost for producing the weight plates  110  is considerably saved. Meanwhile, the weight plates  110  can be bound without the first member  140 . For example, the weight plates  110  can be bound by welding, and in this case the first hole  120  and the first member  140  are not indispensable to the balance weight  100  according to the present invention.  
      The weight plates  110  bound by the first member  140  are secured to the tub  10  by a second member  150 . At least one boss  200  for allowing the second member  150  to be fitted thereto are projected from the outer surface of the tub  10 , and at least one second hole  130  for receiving the second member  150  is provided on the weight plates  110 . The second member  150  passes through the second hole  130  and then coupled to the boss  200  so that the second member  150  stably fits the weight plates  110  onto the tub  10 . However, if necessary, the second member  150  can be separated from the boss  200  with ease.  
      When the washing machine is operated, the tub is vibrated. And, the weight plates  110  are heavy. Thereby a strong force can be applied to the boss  200  when the tub  10  vibrates. Thus, at least one supplementary rib  210  is provided between the outer surface of the tub  10  and an outer surface of the boss  200 . The supplementary rib  210  stably support the boss  200  and reinforces the strength of the boss  200 , thereby the damage of the boss  200  can be prevented.  
      At least one boss hole  135  is provided on the weight plates  110 . The boss hole  200  allows the boss  200  to be inserted therein. It is possible that the boss hole  135  is provided on all of the weight plates  110 . However, in the present invention, the boss hole  135  is provided on partial weight pates bound lower position among all of the weight plates  110  piled up as shown in  FIGS. 3 and 4 . The boss hole  135  has a diameter greater than the second hole&#39;s  130  and substantially as the same as the boss&#39;s  200 .  
      For fitting the weight plates  110  to the tub  10 , the boss  200  of the tub  10  is fitted into the boss hole  135  first. And then, the second member  150  passes through the second hole  130  and is connected to the boss  200 . Thereby, the weight plates  110  are stably secured to the tub  10 . If the boss hole  135  is provided as mentioned above, assembler can temporarily fit the weight plates  110  to the boss  200 , and then can firmly fix the weight plates  110  to the tub  10  using the second member  150 . Thus, the assembler can secure the weight plates  110  to the tub  10  very quickly and very easy.  
      As mentioned above, the balance weight according to the present invention is produced by simple processes including the cutting and the bending metal plates. Thus, time for producing the balance weight is reduced.  
      If heavy weight is necessary for balancing the tub, the assembler can pile a large amount of weight plates up and fit them to the tub with ease for balancing the tub. On the contrary, if light weight is necessary for balancing the tub, assembler can pile a small amount of weight plates up and fit them to the tub with ease for balancing the tub. More particularly, the assembler can adjust the weight of the balancing weight per a weight of one weight plate. As mentioned above, the assembler can adjust the necessary weight for balancing the tub with ease and very accurately.  
      Further, it is possible that waste plates generated when the washing machine is manufactured can be used as the weight plates. Thus, the cost for fabricating the washing machine is reduced. And, the environmental pollution caused by the waste plates can be prevented.  
      It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.