Abstract:
A pulley of a washing machine, wherein the weight of the pulley is reduced by forming a strain-focused portion of the pulley with a high-rigidity material. The pulley of the washing machine having a motor for rotating a drum connected to one end of a shaft, includes a composite member, axially coupled to the other end of the shaft, for transferring a rotational force of the motor to the drum, the composite member being formed of at least two materials having dissimilar tensile strengths.

Description:
[0001]     This application claims the benefit of Korean Application No. P2004-007891, filed on Feb. 6, 2004, which is hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a washing machine, and more particularly, to a pulley of a washing machine transferring a rotational force generated from a motor to a drum.  
         [0004]     2. Discussion of the Related Art  
         [0005]     Generally, a washing machine is a representative home appliance for removing filth or dirt attached to a laundry using a reaction between water and detergent. A washing machine is categorized into various types according to an impacting mechanism on a laundry.  FIG. 1  is a cross-sectional diagram of a washing machine according to a related art. Referring to  FIG. 1 , a washing machine  1  consists of a case  10  forming an exterior and having a door  11  on its front side, a tub  20  fixed within the case  10 , a drum  30  rotatably provided within the tub  20 , and a motor  40  rotating the drum  30 . The washing machine  1  further consists of a belt  50  and pulley  60  to transfer a rotational force of the motor  40  to the drum  30 . The motor  40  is provided under the tub  20  and is connected to the belt  50 . A shaft  31  is provided to a rear side of the drum  30 . And, the pulley  60  is coupled to the shaft  31 .  
         [0006]      FIG. 2  is a front diagram of a pulley according to the related art. Referring to  FIG. 2 , the pulley  60  has a cylindrical shape having an open front side. A groove (not shown) is formed on a circumference of the pulley to be coupled to the belt  50 . A hole  61  is formed in a center of the pulley  60  to be coupled to the shaft  31 . And, the pulley  60  is formed of a steel based material having high rigidity to transfer the rotational force to the drum by overcoming the weight of the drum and the laundry therein. However, the related art pulley of the washing machine is formed of the steel based material, thereby becoming heavy to impose a load on the motor. Hence, damage is caused to the motor.  
       SUMMARY OF THE INVENTION  
       [0007]     Accordingly, the present invention is directed to a pulley of a washing machine that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.  
         [0008]     An object of the present invention, which has been devised to solve the foregoing problem, lies in providing a pulley of a washing machine, by which weight of the pulley is reduced by forming a strain-focused portion of the pulley with a high-rigidity material.  
         [0009]     Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent to those having ordinary skill in the art upon examination of the following or may be learned from a practice of the invention. The objectives and other advantages of the invention will be realized and attained by the subject matter particularly pointed out in the specification and claims hereof as well as in the appended drawings.  
         [0010]     To achieve these objects and other advantages in accordance with the present invention, as embodied and broadly described herein, a pulley of a washing machine having a motor for rotating a drum connected to one end of a shaft, includes a composite member, axially coupled to the other end of the shaft, for transferring a rotational force of the motor to the drum, the composite member being formed of at least two materials having dissimilar tensile strengths.  
         [0011]     The composite member may include a wheel, and an axel piece, centrally disposed with respect to the wheel and coupled to the shaft of the drum, the material of the axel piece having a high tensile strength. Herein, the wheel may have an outer circumference for receiving a power transfer member coupled to the motor. The power transfer member is a belt. The axel piece may include a first contact surface for receiving the shaft, a second contact surface engaging with the wheel, and at least one tooth, radiating toward the outer circumference of the wheel, for increasing the area of the second contact surface and thereby dispersing a mechanical energy transmitted through the second contact surface when the drum is rotated. Herein, the axel piece may include three teeth. The teeth are arranged equidistantly about the axel piece.  
         [0012]     The material of the wheel is more lightweight than the material of the axel piece. And, the wheel may include a rim supported by a plurality of radial spokes. Herein, the wheel may include a hub engaging with the axel piece. And, the axel piece may include a plurality of teeth, radiating toward the rim of the wheel, at least one tooth engaging with the hub at each radial spoke. The axel piece may be formed of steel and the wheel is formed of aluminum. And, the pulley may be formed by an insertion molding process.  
         [0013]     In another aspect of the present invention, a washing machine includes a drum connected to one end of a shaft, a motor for rotating the drum, and a pulley having an inner portion coupled to the other end of the shaft and an outer portion for transferring a rotational force of the motor to the drum, the pulley being a composite of at least two materials having dissimilar tensile strengths, wherein the material of the inner portion has a high tensile strength and the material of the outer portion is more lightweight than the material of the outer portion.  
         [0014]     The outer portion of the pulley may include a rim for receiving a power transfer member, and a plurality of radial spokes supporting the rim. The inner portion of the pulley may include at least one tooth for increasing a contact surface area engaging with the outer portion of the pulley, the at least one tooth engaging with the outer portion at each radial spoke. Herein, the inner portion of the pulley may be formed of steel, and the outer portion of the pulley may be formed of aluminum. The pulley may be manufactured by an insertion molding process.  
         [0015]     It is to be understood that both the foregoing explanation and the following detailed description of the present invention are exemplary and illustrative and are intended to provide further explanation of the invention as claimed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     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 embodiments of the invention and together with the description serve to explain the principle of the invention. In the drawings:  
         [0017]      FIG. 1  is a cross-sectional diagram of a washing machine according to a related art;  
         [0018]      FIG. 2  is a front diagram of a pulley according to the related art;  
         [0019]      FIG. 3  is a cross-sectional diagram of a washing machine according to the present invention; and  
         [0020]      FIG. 4  is a front diagram of a pulley according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Throughout the drawings, like elements are indicated using the same or similar reference designations where possible.  
         [0022]      FIG. 3  is a cross-sectional diagram of a washing machine according to the present invention, and  FIG. 4  is a front diagram of a pulley according to the present invention. Referring to  FIG. 3 , a case  110  forms an exterior of a washing machine  100  according to the present invention. A tub  120  is suspended within the case  110 . For this, an upper part of the tub  120  is connected to a spring  140  fixed to the case  110  and a lower part of the tub  120  is connected to a damper  150  connected to a bottom surface of the case  110  via a hinge. The above-provided spring  140  and damper  150  play a role in attenuating vibration appearing on the tub  120  in the course of operating a washing machine as well as elastically suspending the tub  120  within the case  110 .  
         [0023]     A drum  130  is rotatably provided within the tub  120 , which is explained in detail as follows. First of all, a multitude of perforated holes  131  perforate a circumference of the drum  130  and a plurality of tumbling ribs  132  are provided on an inner circumference of the drum  130 . Hence, water supplied to the tub  120  enables to communicate between the drum  130  and the tub  120  via the perforated holes  131 . A laundry held (or contained) in the drum  130  is lifted upward to fall by the tumbling ribs  132  while the drum  130  is rotated. Hence, friction and impact energy sufficient for washing can be provided when the laundry falls by the tumbling ribs  132 . An opening  111  is provided to a front side of the case  110  so that a user can put/pull the laundry in/from the drum  130  and a door  112  is provided to open/close the opening  111 . A gasket  113  is provided between the opening  111  of the case  110  and the tub  120  to prevent water/laundry held in the drum  130  and/or tub  120  from leaking/escaping.  
         [0024]     Meanwhile, a water supply system  160  and drain system  170  are provided within the case  110 . The water supply system  160  includes an inlet valve  161 , an inlet hose  162 , a detergent box  163 , and an inlet bellows  164 . The inlet valve  161  opens or closes a passage of water supplied from outside, and the inlet hose  162  connects the inlet valve  161  and the detergent box  163 . And, the inlet bellows  164  connects the detergent box  163  and the tub  120 . Once the inlet valve  161  is turned on, water is passed through the inlet hose  162 , the detergent box  163 , and the inlet bellows  164  in turn to be supplied to the tub  130 . In this case, a detergent stored in the detergent box  163  is supplied to the water if necessary.  
         [0025]     The drain system  170  includes a drain bellows  171 , a drain pump  172 , and a drain hose  173 . The drain bellows  171  connects the tub  120  and the drain pump  172 . One end of the drain hose  173  is connected to the drain pump  172  and the other end of the drain hose  173  communicates with outside of the case  110 . Hence, once the drain pump  172  is driven, water held in the tub  120  is passed through the drain bellows  171 , the drain pump  172 , and the drain hose  173  in turn to be discharged outside.  
         [0026]     Meanwhile, in order to rotate the drum  130 , a motor  180  is provided within the case  110 , and more particularly, under the tub  120 . And, a pulley  200  and a power transfer member  190  are provided to transfer a rotational force of the motor  180  to the drum  130 . In order to provide the rotational force generated from the motor  180  to the drum  130 , the pulley  200  is coupled to the shaft  133  provided to the rear side of the drum  130  and is connected to the motor  180  by the power transfer member  190 . In this case, the power transfer member  190  is a belt.  
         [0027]     The pulley  200  includes a member  210  formed of at least two materials differing in rigidity from each other. Alternatively, one portion of the pulley  200  connected to the shaft  133  is formed of a high-rigidity material and the rest portion of the pulley  200  is formed of a lightweight material. The pulley  200  is explained in detail with reference to  FIG. 4  as follows. The member includes a first member  220  coupled to the shaft  133  of the drum  130  and a second member  220  enclosing the first member  220 . When the pulley  200  rotates the drum  130 , strain is generated from the corresponding coupling part  221 . The first member  220  is formed of a high-rigidity material to resist the strain focused on the portion where the shaft  133  is coupled. Specifically, the first member  220  includes a coupling part  221  coupled to the shaft  133  and a protruding part  222  protruding from the coupling part  221  to extend a contact area with the second member  230 . In this case, the protruding part  222  plays a role in dispersing to transfer the strain to the generated second member  230 .  
         [0028]     Moreover, in order to disperse the strain more efficiently, the protruding part  222  protrudes from the coupling part  221  in three directions to leave a same interval from each other. Meanwhile, the second member  230  is formed of a lightweight material having rigidity lower than that of the first member  220 . Specifically, the second member  230  includes a rim  231  having the power transfer member  190  wound thereon and a spoke  233  connecting the first member  210  and the rim  231 . Moreover, a groove (not shown) is formed on an outer circumference of the rim  231  to have the power transfer member  190  fitted therein solidly.  
         [0029]     The spoke  232  formed of a low-rigidity material may be transformed by the strain. In order to prevent the transformation of the spoke  232 , the protruding part  222  is inserted in the spoke  232  to reinforce the spoke  232 . By increasing the contact area between the spoke  232  and the protruding part  222 , the strain is dispersed to prevent the spoke  232  from being damaged. Moreover, there are provided three spokes  232  to evenly support the rim  231 . If the three spokes  232  are provided, less material is required for manufacturing the pulley  200 . Preferably, the spokes  232  are arranged to leave the same interval from each other.  
         [0030]     The materials of the pulley  200  are explained in detail as follows. First of all, the first member  220  is formed of steel having high rigidity and the second member  230  is formed of lightweight aluminum having low rigidity. Besides, the pulley  200  is preferably manufactured by insert molding.  
         [0031]     The washing machine according to the present invention is operated in the following manner. First of all, after the drum  130  is filled with laundry, water, and detergent, the moor  180  is driven to rotate the pulley  200  via the power transfer member  190 . As the pulley  200  is rotated, the drum  130  connected to the pulley  200  via the shaft  133  is rotated. By rotating the drum  130 , the laundry is washed within the drum  130 .  
         [0032]     In doing so, the weight of the drum including the laundry therein causes strain to the shaft and pulley. Yet, one portion of the pulley is formed of the high-rigidity material, thereby preventing the pulley from being broken by the strain. Moreover, the rest portion of the pulley is formed of the lightweight material to reduce the weight of the pulley. Thus, the load applied to the motor is reduced, whereby the motor enables to avoid being damaged. And, the one portion of the pulley is inserted in the rest portion to reinforce the rest portion and to increase the contact area between the one portion and the rest portion. Hence, the strain is dispersed to the rest portion from the one portion, whereby the pulley is prevented from being broken.  
         [0033]     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 invention. Thus, it is intended that the present invention cover such modifications and variations, provided they come within the scope of the appended claims and their equivalents.