Abstract:
A drum type washing machine including a housing, a spin tub, and a ball balancer coupled to the spin tub, the ball balancer including a first plastic member and a second plastic member joined to each other to form an annular-shaped race, the first plastic member including a first side wall, a second side wall and a connecting wall to form a three-sided annular-shaped structure having an open side, and the second plastic member adapted to cover the open side, the three-sided annular-shaped structure having a U-shaped cross-section with a first rounded inside corner formed between the first side wall and the connecting wall and a second rounded inside corner formed between the second side wall and the connecting wall. A radius of curvature of each of the first and second rounded inside corners is greater than a radius of curvature of opposite diagonal inside corners of the annular-shaped race.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of U.S. application Ser. No. 13/064,987, filed Apr. 29, 2011, which was a continuation of U.S. application Ser. No. 12/801,952, filed Jul. 2, 2010, which was a continuation of U.S. application Ser. No. 12/659,980, filed Mar. 26, 2010, which issued as U.S. Pat. No. 7,797,970, which was a divisional of U.S. application Ser. No. 11/806,245, filed May 30, 2007, which issued as U.S. Pat. No. 7,743,633, which in turn claims the benefit of Korean Patent Application Nos. 2006-49501 and 2006-49482, both filed on Jun. 1, 2006, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The present invention relates generally to a washing machine having at least one balancer, and more particularly to a washing machine having at least one balancer that increases durability by reinforcing strength and that is installed on a rotating tub in a convenient way. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, washing machines do the laundry by spinning a spin tub containing the laundry by driving the spin tub with a driving motor. In a washing process, the spin tub is spun forward and backward at a low speed. In a dehydrating process, the spin tub is spun in one direction at a high speed. 
         [0006]    When the spin tub is spun at a high speed in the dehydrating process, if the laundry leans to one side without uniform distribution in the spin tub or if the laundry leans to one side by an abrupt acceleration of the spin tub in the early stage of the dehydrating process, the spin tub undergoes a misalignment between the center of gravity and the center of rotation, which thus causes noise and vibration. The repetition of this phenomenon causes parts, such as a spin tub and its rotating shaft, a driving motor, etc., to break or to undergo a reduced life span. 
         [0007]    Particularly, a drum type washing machine has a structure in which the spin tub containing laundry is horizontally disposed, and when the spin tub is spun at a high speed when the laundry is collected on the bottom of the spin tub by gravity in the dehydrating process, the spin tub undergoes a misalignment between the center of gravity and the center of rotation, thus resulting in a high possibility of causing excess noise and vibration. 
         [0008]    Thus, the drum type washing machine is typically provided with at least one balancer for maintaining a dynamic balance of the spin tub. A balancer may also be applied to an upright type washing machine in which the spin tub is vertically installed. 
         [0009]    An example of a washing machine having ball balancers is disclosed in Korean Patent Publication No. 1999-0038279. The ball balancers of a conventional washing machine include racers installed on the top and the bottom of a spin tub in order to maintain a dynamic balance when the spin tub is spun at a high speed, and steel balls and viscous oil are disposed within the racers to freely move in the racers. 
         [0010]    Thus, when the spin tub is spun without maintaining a dynamic balance due to an unbalanced eccentric structure of the spin tub itself and lopsided distribution of the laundry in the spin tub, the steel balls compensate for this imbalance, and thus the spin tub can maintain the dynamic balance. 
         [0011]    However, the ball balancers of the conventional washing machine have a structure in which upper and lower plates formed of plastic by injection molding are fused to each other, and a plurality of steel balls are disposed between the fused plates to make a circular motion, so that the ball balancers are continuously supplied with centrifugal force that is generated when the steel balls make a circular motion, and thus are deformed at walls thereof, which reduces the life span of the balancer. 
         [0012]    Further, the ball balancers of the conventional washing machine do not have a means for guiding the ball balancers to be installed on the spin tub in place, so that it takes time to assemble the balancers to the spin tub. 
         [0013]    In addition, the ball balancers of the conventional washing machine have a structure in which a racer includes upper and lower plates fused to each other, so that fusion scraps generated during fusion fall down both inwardly and outwardly of the racer. The fusion scraps that fall down inwardly of the racer prevent motion of the balls in the racer, and simultaneously result in generating vibration and noise. 
       SUMMARY 
       [0014]    Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a washing machine having at least one balancer that increases durability by reinforcing the strength of the balancer, which is installed on a rotating tub in a rapid and convenient way. 
         [0015]    Another object of the present invention is to provide a washing machine having at least one balancer, in which fusion scraps generated by fusion of the balancer are prevented from falling down inward and outward of the balancer. 
         [0016]    Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention. 
         [0017]    In order to accomplish these objects, according to an aspect of the present invention, there is provided a washing machine having a spin tub to hold laundry to be washed and at least one balancer. The balancer includes first and second housings, the first housing having at least one support for reinforcing a strength of the balancer. The first and second housings have an annular shape and are fused together to form a closed internal space. 
         [0018]    Here, the first housing may have the cross section of an approximately “C” shape, and the support protrudes outwardly from at least one of opposite walls of the first housing. 
         [0019]    Further, the spin tub may include at least one annular recess corresponding to the balancer such that the balancer is able to be coupled to the spin tub by being fitted within the recess. 
         [0020]    Further, the support may protrude from the first housing and comes into contact with a wall of the recess, and guides the balancer to be maintained in the recess in place. 
         [0021]    Also, the supports may be continuously formed along and perpendicular to the opposite walls of the first housing. 
         [0022]    Further, the supports may be disposed parallel to the opposite walls of the first housing at regular intervals. 
         [0023]    Meanwhile, the washing machine may be a drum type washing machine. A front member may be attached to a front end of the spin tub and a rear member may be attached to a rear end of the spin tub. The recesses may be provided at the front and rear members of the spin tub, and the balancers may be coupled to opposite ends of the spin tub at the recesses of the front and rear members. 
         [0024]    The foregoing and/or other aspects of the present invention can be achieved by providing a washing machine having at least one balancer. The balancer includes a first housing and a second housing fused to the first housing, and the first and second housings are fused together to form at least one pocket between the first housing and the second housing, the pocket capable of collecting fusion scraps generated during fusion. 
         [0025]    Here, the first housing may include protruding fusion ridges protruding from ends of the first housing, and the second housing may include fusion grooves receiving the fusion ridges of the first housing when the first housing and the second housing are fused together. 
         [0026]    Further, the first housing may further include inner pocket ridges protruding from the first housing and spaced inwardly apart with respect to the fusion ridges of the first housing. 
         [0027]    Further, the second housing may further include outer pocket flanges protruding from the second housing and being situated on outer sides of the fusion grooves when the first housing is fused together with the second housing so the outer pocket flanges are spaced apart from the fusion ridges of the first housing by a predetermined distance, causing an outer pocket to be formed between the fusion ridges and the outer pocket flanges. 
         [0028]    Further, the second housing may include guide ridges protruding from the second housing and protruding toward the first housing to closely contact the inner pocket ridges of the first housing when the first and second housings are fused together. 
         [0029]    Also, the balancer may further include a plurality of balls disposed within an internal space formed by fusing the first and second housings together, the balls performing a balancing function. 
         [0030]    In addition, the washing machine may further include a spin tub disposed horizontally, and the balancers may be installed at front and rear ends of the spin tub. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    The above and other aspects, features and advantages of the present invention will be more apparent from the following detailed description of the embodiments, taken in conjunction with the accompanying drawings, in which 
           [0032]      FIG. 1  is a sectional view illustrating a schematic structure of a washing machine according to the present invention; 
           [0033]      FIG. 2  is a perspective view illustrating balancers according to the present invention, in which the balancers are disassembled from a spin tub; 
           [0034]      FIG. 3  is a perspective view illustrating a balancer according to a first embodiment of the present invention; 
           [0035]      FIG. 4  is an enlarged view illustrating section A of  FIG. 1  in order to show the sectional structure of a balancer according to a first embodiment of the present invention; 
           [0036]      FIG. 5  is a perspective view illustrating a balancer according to a second embodiment of the present invention; 
           [0037]      FIG. 6  is an enlarged view illustrating the sectional structure of a balancer according to the second embodiment of the present invention; 
           [0038]      FIG. 7  is a perspective view illustrating a disassembled balancer according to a third embodiment of the present invention; 
           [0039]      FIG. 8  is a perspective view illustrating an assembled balancer according to the third embodiment of the present invention; 
           [0040]      FIG. 9  is a partially enlarged view of  FIG. 7 ; and 
           [0041]      FIG. 10  is a sectional view taken line A-A of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0042]    Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures. 
         [0043]    Hereinafter, exemplary embodiments of the present invention will be described with reference to the attached drawings. 
         [0044]      FIG. 1  is a sectional view illustrating the schematic structure of a washing machine according to the present invention. 
         [0045]    As illustrated in  FIG. 1 , a washing machine according to the present invention includes a housing  1  forming an external structure of the washing machine, a water reservoir  2  installed in the housing  1  and containing washing water, a spin tub  10  disposed rotatably in the water reservoir  2  which allows laundry to be placed in and washed therein, and a door  4  hinged to an open front of the housing  1 . 
         [0046]    The water reservoir  2  has a feed pipe  5  and a detergent feeder  6  both disposed above the water reservoir  2  in order to supply washing water and detergent to the water reservoir  2 , and a drain pipe  7  installed therebelow in order to drain the washing water contained in the water reservoir  2  to the outside of the housing  1  when the laundry is completely done. 
         [0047]    The spin tub  10  has a rotating shaft  8  disposed at the rear thereof so as to extend through the rear of the water reservoir  2 , and a driving motor  9 , with which the rotating shaft  8  is coupled, installed on a rear outer side thereof. Therefore, when the driving motor  9  is driven, the rotating shaft  8  is rotated together with the spin tub  10 . 
         [0048]    The spin tub  10  is provided with a plurality of dehydrating holes  10   a  at a periphery thereof so as to allow the water contained in the water reservoir  2  to flow into the spin tub  10  together with the detergent to wash the laundry in a washing cycle, and to allow the water to be drained to the outside of the housing  1  through a drain pipe  7  in a dehydrating cycle. 
         [0049]    The spin tub  10  has a plurality of lifters  10   b  disposed longitudinally therein. Thereby, as the spin tub  10  rotates at a low speed in the washing cycle, the laundry submerged in the water is raised up from the bottom of the spin tub  10  and then is lowered to the bottom of the spin tub  10 , so that the laundry can be effectively washed. 
         [0050]    Thus, in the washing cycle, the rotating shaft  8  alternately rotates forward and backward by of the driving of the driving motor  9  to spin the spin tub  10  at a low speed, so that the laundry is washed. In the dehydrating cycle, the rotating shaft  8  rotates in one direction to spin the spin tub  10  at a high speed, so that the laundry is dehydrated. 
         [0051]    When spun at a high speed in the dehydrating process, the spin tub  10  itself may undergo misalignment between the center of gravity and the center of rotation, or the laundry may lean to one side without uniform distribution in the spin tub  10 . In this case, the spin tub  10  does not maintain a dynamic balance. 
         [0052]    In order to prevent this dynamic imbalance to allow the spin tub  10  to be spun at a high speed with the center of gravity and the center of rotation thereof matched with each other, the spin tub  10  is provided with balancers  20  or  30  according to a first or a second embodiment of the present invention (wherein only the balancer  20  according to a first embodiment is shown in  FIGS. 1-4 ) at front and rear ends thereof. The structure of the balancers  20  and  30  according to the first and second embodiments of the present invention will be described with reference to  FIGS. 2 through 6 . 
         [0053]      FIG. 2  is a perspective view illustrating balancers according to the present invention, in which the balancers are disassembled from a spin tub. 
         [0054]    As illustrated in  FIG. 2 , the spin tub  10  includes a cylindrical body  11  that has open front and rear parts and is provided with the dehydrating holes  10   a  and lifters  10   b , a front member  12  that is coupled to the open front part of the body  11  and is provided with an opening  14  permitting the laundry to be placed within or removed from the body  11 , and a rear member  13  that is coupled to the open rear part of the body  11  and with the rotating shaft  8  (see  FIG. 1 ) for spinning the spin tub  10 . 
         [0055]    The front member  12  is provided, at an edge thereof, with an annular recess  15  that has the cross section of an approximately “C” shape and is open to the front of the front member  12  in order to hold any one of the balancers  20 . Similarly, the rear member  13  is provided, at an edge thereof, with an annular, recess  15  (not shown) that is open to the rear of the front member  12  in order to hold the other of the balancers  20 . 
         [0056]    The front and rear members  12  and  13  are fitted into and coupled to the front or rear edges of the body  11  in a screwed fashion or in any other fashion that allows the front and rear members  12  and  13  to be maintained to the body  11  of the spin tub  10 . 
         [0057]    The balancers  20 , which are installed in the recesses  15  of the front and rear members  12  and  13 , have an annular shape and are filled therein with a plurality of metal balls  21  performing a balancing function and a viscous fluid (not shown) capable of adjusting a speed of motion of the balls  21 . 
         [0058]    Now, the structure of the balancers  20  and  30  according to the first and second embodiments of the present invention will be described with reference to  FIGS. 3 through 6 . 
         [0059]      FIG. 3  is a perspective view illustrating a balancer according to a first embodiment of the present invention, and  FIG. 4  is an enlarged view illustrating part A of  FIG. 1  in order to show the sectional structure of a balancer according to a first embodiment of the present invention. 
         [0060]    As illustrated in  FIGS. 3 and 4 , a balancer  20  according to a first embodiment of the present invention has an annular shape and includes first and second housings  22  and  23  that are fused to define a closed internal space  20   a.    
         [0061]    The first housing  22  has first and second walls  22   a  and  22   b  facing each other, and a third wall  22   c  connecting ends of the first and second walls  22   a  and  22   b , and thus has a cross section of an approximately “C” shape. The second housing  23  has opposite edges that protrude toward the first housing  22  and that are coupled to corresponding opposite ends  22   d  of the first housing  22  by heat fusion. 
         [0062]    The opposite ends  22   d  of the first housing  22  protrude outward from the first and second walls  22   a  and  22   b  of the first housing  22 , and the edges of the second housing  23  are sized to cover the ends  22   d  of the first housing  22 . 
         [0063]    Thus, when the balancer  20  is fitted into the recess  15  of the front member  12  of the spin tub  10 , the first and second walls  22   a  and  22   b  are spaced apart from a wall of the recess  15  because of the ends and edges of the first and second housings  22  and  23  which protrude outward from the first and second walls  22   a  and  22   b . Further, because the first and second walls  22   a  and  22   b  are relatively thin, the first and second walls  22   a  and  22   b  are raised outward when centrifugal force is applied thereto by the plurality of balls  21  that move in the internal space  20   a  of the balancer  20  in order to perform the balancing function. 
         [0064]    In this manner, the plurality of balls  21  make a circular motion in the balancer  20 , so that the first and second walls  22   a  and  22   b  are deformed by the centrifugal force applied to the first and second walls  22   a  and  22   b  of the first housing  22 . In order to prevent this deformation, the second housing  22  is provided with supports  24  according to a first embodiment of the present invention. 
         [0065]    The supports  24  protrude from and perpendicular to the first and second walls  22   a  and  22   b  of the first housing  22  which are opposite each other, and may be continued along an outer surface of the first housing  22 , thereby having an overall annular shape. 
         [0066]    The supports  24  have a length such that they extend from the first housing  22  to contact the wall of the recess  15 . Hence, the first and second walls  22   a  and  22   b  are further increased in strength, and additionally function to guide the balancer  20  so as to be maintained in the recess  15  in place. 
         [0067]    Here, when the plurality of balls  21  make a circular motion in the first housing  22 , the centrifugal force acts in the direction moving away from the center of rotation of the spin tub  10 . Hence, the centrifugal force acts on the first wall  22   a  to a stronger level when viewed in  FIG. 4 . Thus, the supports  24  may be formed only on the first wall  22   a.    
         [0068]    In the balancer  20  according to the first embodiment of the present invention, when the first and second housings  22  and  23  are fused together and fitted into the recess  15  of the spin tub  10 , the supports  24  are maintained in place while positioned along the wall of the recess  15 . Finally, the balancer  20  is coupled and fixed to the front member  12  of the spin tub  10  by screws (not shown) or in any other fashion that allows the balancer  20  to be coupled to the front member  12 . 
         [0069]    Although not illustrated in detail, the balancer  20  is similarly installed on the rear member  13  of the spin tub  10 . 
         [0070]    The ends  22   d  of the first housing  22  include fusion ridges  42   a  that protrude toward the second housing  23 . The fusion ridges  42   a  are inserted within fusion grooves  43   a  of the second housing  23 . 
         [0071]      FIGS. 5 and 6  correspond to  FIGS. 3 and 4 , and illustrate a balancer  30  according to a second embodiment of the present invention. 
         [0072]    The balancer  30  according to the second embodiment of the present invention has an annular shape and includes first and second housings  32  and  33  that are fused together forming an internal space  30   a  therebetween in which a plurality of balls  31  are disposed. The balancer  30  according to the second embodiment of the present invention is similar to that of balancer  20  according to the first embodiment of the present invention, except the structure of supports  34  of balancer  30  is different from that of the structure of the supports  24  of balancer  20 . 
         [0073]    As illustrated in  FIGS. 5 and 6 , the supports  34  according to the second embodiment of the present invention protrude parallel to first and second walls  32   a  and  32   b  of a first housing  32  which are opposite each other, and the supports  34  are disposed at regular intervals along the first and second walls  32   a  and  32   b . The first housing  32  further includes a third wall  32   c . Ends  22   d  of the first housing  32  extend from an end of the first and second walls  32   a  and  32   b.    
         [0074]    Similar to the supports  24  according to the first embodiment, the supports  34  of the second embodiment have a length such that the supports  34  extend from the first housing  32  to contact the wall of the recess  15 . The surfaces of the supports  34  thereby abut portions of the front member  12 . Hence, the first and second walls  32   a  and  32   b  are further increased in strength, and additionally function to guide the balancer  30  so as to be maintained in the recess  15  in place. 
         [0075]    Next, the construction of a balancer  40  according to a third embodiment of the present invention will be described with reference to  FIGS. 7 through 10 . 
         [0076]      FIGS. 7 and 8  are perspective views illustrating disassembled and assembled balancers according to the third embodiment of the present invention,  FIG. 9  is a partially enlarged view of  FIG. 7 , and  FIG. 10  is a sectional view taken along line A-A of  FIG. 8 . 
         [0077]    As illustrated in  FIGS. 7 and 8 , a balancer  40  includes a first housing  42  having an annular shape and a second housing  43  having an annular shape that is fused to the first housing  42 , thereby forming an annular housing corresponding to the recess  15  (see  FIG. 2 ) of the spin tub  10 . The first and second housings  42  and  43  may be, for example, formed of synthetic resin, such as plastic by injection molding. 
         [0078]    As illustrated in  FIG. 9 , the first housing  42  has a cross section of an approximately “C” shape, includes fusion ridges  42   a  protruding to the second housing  43  at opposite ends thereof which are coupled with the second housing  43 , and inner pocket ridges  42   b  protruding to the second housing  43  spaced inwardly apart from the fusion ridges  42   a.    
         [0079]    The second housing  43 , which is coupled to opposite ends of the first housing  42  in order to form a closed internal space  40   a  for holding a plurality of balls  41  and a viscous fluid, includes fusion grooves  43   a  recessed along edges thereof so as to correspond to the fusion ridges  42   a , outer pocket flanges  43   b  and guide ridges  43   c . The outer pocket flanges protrude to the first housing  42  on outer sides of the fusion grooves  43   a  so as to be spaced apart from the fusion ridges  42   a  of the first housing  42  by a predetermined distance. The guide ridges  43   c  protrude to the first housing  42  on inner sides of the fusion grooves  43   a  and closely contact the inner pocket ridges  42   b  of the first housing  42 . 
         [0080]    The guide ridges  43   c  of the second housing  43  move in contact with the inner pocket ridges  42   b  of the first housing  42  when the second housing  43  is fitted into the first housing  42 , to thereby guide the fusion ridges  42   a  of the first housing  42  to be fitted into the fusion grooves  43   a  of the second housing  43  rapidly and precisely. 
         [0081]    Thus, when the fusion ridges  42   a  of the first housing  42  are fitted into the fusion grooves  43   a  of the second housing  43  in order to fuse the first housing  42  with the second housing  43 , as shown in  FIG. 10 , an inner pocket  40   b  having a predetermined spacing is formed between the fusion ridges  42   a  and inner pocket ridges  42   b , and an outer pocket  40   c  having a predetermined spacing is formed between the fusion ridges  42   a  and the outer pocket flanges  43   b.    
         [0082]    In this state, when heat is generated between the fusion ridges  42   a  of the first housing  42  and the fusion grooves  43   a  of the second housing  43 , the fusion ridges  42   a  and the fusion grooves  43   a  are firmly fused with each other. At fusion, fusion scraps that are generated by heat and fall down inward of the first housing  42  are collected in the inner pocket  40   b , so that the scraps are not introduced into the internal space  40   a  of the balancer  40  in which the balls  41  move. Fusion scraps falling down outward of the first housing  42  are collected in the outer pocket  40   c , and thus are prevented from falling down outward of the balancer  40 . 
         [0083]    In the embodiments, the balancers  20 ,  30  and  40  have been described to be installed on a drum type washing machine by way of example, but it is apparent that the balancers can be applied to an upright type washing machine having a structure in which a spin tub is vertically installed. 
         [0084]    As described above in detail, the washing machine according to the embodiments of the present invention has a high-strength structure in which at least one balancer is provided with at least one support protruding outward from the wall thereof, so that, although the strong centrifugal force acts on the wall of the balancer due to a plurality of balls making a circular motion in the balancer, the wall of the balancer is not deformed. Thus, the plurality of balls can make a smooth circular motion without causing excess vibration and noise, and thus increasing the durability and life span of the balancer. 
         [0085]    Further, the washing machine according to the embodiments of the present invention has a structure in which the balancer can be rapidly and exactly positioned in the recess of the spin tub by the supports, so that an assembly time of the balance can be reduced. 
         [0086]    In addition, the washing machine according to the present invention has a structure in which fusion scraps generated when the balancer is fused are collected in a plurality of pockets, and thus are prevented from falling down inward and outward of the balancer, so that the internal space of the balancer, in which a plurality of balls are filled and move in a circular motion, has a smooth surface without the addition of fusion scraps. As a result, the balls are able to move more smoothly, and excess noise and vibration are minimized. The balancer may have a clear outer surface to provide a fine appearance without the fusion scraps, so that it can be exactly coupled to the spin tub without obstruction caused by the fusion scraps. 
         [0087]    Although a few embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims and their equivalents.