Abstract:
A washing machine includes: a cabinet forming an external appearance; an outer tub hanging within the cabinet and having an open upper portion allowing the clothes to enter therethrough, and allowing washing water to be put therein; and an inner tub disposed within the outer tub and rotating based on a vertical shaft, wherein the outer tub includes: a base through which a driving shaft rotating the inner tub; and a side wall part extending upward from the base to form a side wall of the outer tub and having a lower portion thicker than an upper portion thereof. The increase in weight according to an increase in capacity can be reduced and a loss of rigidity can be to minimized. Also, because the center of gravity is removed to a lower side, stability with respect to vibrations can be obtained.

Description:
[0001]    This application claims priority from Korean Patent Application No. 10-2009-0029135 filed on Apr. 3, 2009 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a washing machine and, more particularly, to a washing machine having a structure in which a lower portion of a side wall of an outer tub is thicker than a lower portion of the side wall of the outer tub, having a large capacity, and having an improved stability with respect to vibrations. 
         [0004]    2. Description of the Related Art 
         [0005]    A washing machine generally refers to various devices for processing the laundry by applying a physical and chemical action to the laundry, such as a laundry machine for detaching a contaminant from the clothes, bedclothes, and the like, (referred to as the ‘laundry’, hereinafter) by using a chemical decomposition operation between water and a detergent and a physical operation such as friction between water and the laundry, a dryer for spin-drying the wet laundry; and a refresher for injecting (or spraying) heated stem to the laundry to prevent an allergy due to the laundry, and simply washing the laundry. 
         [0006]    However, the related art washing machine has a problem in that an increase in size of an outer tub leads to an excessive increase in weight, so it is not easy to allow the outer tub to have a large capacity. Also, the increase in the weight of the outer tub causes an inner tub and the outer tub to collide because rigidity is degraded when the inner tub rotates at a high speed. Thus, the rotational speed of the inner tub must be necessarily reduced in order to avoid collision of the inner tub and the outer tub, which, however, disadvantageously leads to degradation of a washing performance. 
       SUMMARY OF THE INVENTION 
       [0007]    Thus, an object of the present invention is to provide a washing machine having a structure in which the thickness of a lower portion of an outer tub is thicker than that of an upper portion of the outer tub to minimize an increase in the weight of the outer tub as the outer tub has a large capacity to thus secure a sufficient rigidity, and to form the center of gravity of the outer tub at a relatively lower side to thus obtain stability with respect to vibrations. 
         [0008]    According to an aspect of the present invention, there is provided a washing machine including: a cabinet forming an external appearance; an outer tub hanging within the cabinet and having an open upper portion allowing the clothes to enter therethrough, and allowing washing water to be put therein; and an inner tub disposed within the outer tub and rotating based on a vertical shaft, wherein the outer tub includes: a base part through which a driving shaft rotating the inner tub; and a side wall part extending upward from the base to form a side wall of the outer tub and having a lower portion thicker than an upper portion thereof. 
         [0009]    According to another aspect of the present invention, there is provided a washing machine including: a cabinet forming an external appearance; an outer tub hanging within the cabinet and having an open upper portion allowing the clothes to enter therethrough, and allowing washing water to be put therein; and an inner tub disposed within the outer tub and rotating based on a vertical shaft, wherein the outer tub has a side wall part extending vertically, a lower portion of the side wall part is thicker than an upper portion of the side wall part. 
         [0010]    According to another aspect of the present invention, there is provided a washing machine including: a cabinet forming an external appearance; an outer tub hanging within the cabinet and having an open upper portion allowing the clothes to enter therethrough, and allowing washing water to be put therein; and an inner tub disposed within the outer tub and rotating based on a vertical shaft, wherein the outer tub includes a side wall part configured such that the thickness of a lower portion of the side wall part is larger than that of an upper portion of the side wall part, so that the center or gravity is formed at a relatively lower side while having the same weight compared with a case where the side wall part is formed to have a uniform thickness. 
         [0011]    According to a washing machine of the present invention, one or more effects as follows may be achieved. 
         [0012]    First, because the center of gravity of the outer tub is formed at a relatively lower side, stability with respect to vibrations can be obtained. 
         [0013]    Second, when the inner tub rotates at a high speed, the inner tub is prevented from colliding with the outer tub. 
         [0014]    Third, an increase in the weight as the outer tub has a large capacity can be minimized. 
         [0015]    The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned above can be clearly understood from the definitions in the claims by one skilled in the art. 
         [0016]    The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
           [0018]    In the drawings: 
           [0019]      FIG. 1  is a side sectional view of a washing machine according to an exemplary embodiment of the present invention; 
           [0020]      FIG. 2  is an enlarged view of a portion ‘A’ in  FIG. 1 ; 
           [0021]      FIG. 3  is a front view of an outer tub illustrated in  FIG. 1 ; 
           [0022]      FIG. 4  is a sectional view of the portion ‘B’ in  FIG. 3 ; 
           [0023]      FIG. 5  is an enlarged view of a portion ‘C’ in  FIG. 3 ; 
           [0024]      FIG. 6  is a front view of an outer tub according to another exemplary embodiment of the present invention; 
           [0025]      FIG. 7  is a sectional view of a portion ‘D in  FIG. 6 ; 
           [0026]      FIG. 8  is a front view of an outer tub according to still another exemplary embodiment of the present invention; and 
           [0027]      FIG. 9  is a sectional view of a portion ‘E’ in  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the shapes and dimensions may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like components. 
         [0029]      FIG. 1  is a side sectional view of a washing machine according to an exemplary embodiment of the present invention.  FIG. 2  is an enlarged view of a portion ‘A’ in  FIG. 1 .  FIG. 3  is a front view of an outer tub illustrated in  FIG. 1 .  FIG. 4  is a sectional view of the portion ‘B’ in  FIG. 3 .  FIG. 5  is an enlarged view of a portion ‘C’ in  FIG. 3 . 
         [0030]    A washing machine  100  according to an exemplary embodiment of the present invention includes a cabinet  111  forming an external appearance and having an open upper portion, a cabinet cover  112  covering the open upper portion of the cabinet  111  and having a clothes entry opening allowing the clothes to enter therethrough, a control panel  119  mounted on the cabinet  111  and receiving an operation instruction from a user, a door  113  for opening and closing the clothes entry opening; an outer tub  120  hanging in the interior of the cabinet  111  by a support member  117  and buffered by a damper  118 , and an inner tub  115  disposed at an inner side of the outer tub  120 , rotating based on a vertical shaft, and accommodating the clothes. Here, a plurality of water holes (not shown) are formed on the inner tub  115  to allow washing water to circulate between the outer tub  120  and the inner tub  115 , and an outer tub cover  114  is formed on an upper portion of the outer tub  120  and has a clothes entry hole (h) formed to be open. A pulsator  116  is provided on the bottom of the inner tub  115  in order to form a rotatory water current, and a motor  130  is disposed at a lower side of the outer tub  120  to generate rotatory power to rotate the inner tub  115  and/or the pulsator  116 . Also, a drain hose  142  and a drain pump  144  may be provided to drain washing water out of the outer tub  120 . 
         [0031]    The outer tub  120  includes a base part  121  forming a bottom surface of the outer tub  120  and a side wall part  122  extending substantially vertically from the base part  121 . A driving shaft  132  rotated by the motor  130  penetrates the base part  121 , and the base part  121  includes a bearing housing  121   a  for accommodating a driving shaft bearing  134  supporting the driving shaft  132 . Meanwhile, the side wall part  122  may not be necessarily the entire side wall of the outer tub  120 , and may be defined as a portion or the entirety of the side wall. 
         [0032]    In general, when the side wall of the outer tub  120  is formed with a uniform thickness (hereinafter, the outer tub having an outer wall with a uniform thickness will be referred to as a ‘comparison body’), the thickness of the side wall of the comparison body is determined in consideration of the weight of washing machine and the rigidity corresponding to the characteristics of vibrations generated when the inner tub  115  rotates. In this case, the thickness is determined in consideration of the overall load in a state that the clothes and washing water are present in the comparison body. The side wall of the comparison body must be formed to tolerate the overall load in any portion thereof. Thus, if a lower portion of the side wall to which the load is concentrated needs to be formed to have a thickness of 2.4 mm, the side wall of the comparison body is to be formed with a uniform thickness of 2.4 mm or larger overall. 
         [0033]    Under the same conditions, in order to maintain a sufficient rigidity, the thickness of the lower portion of the side wall part  122  of the outer tub  120  according to an exemplary embodiment of the present invention must be 2.4 mm or larger. With reference to  FIGS. 4 and 5 , the side wall part  122  is formed such that the thickness of its upper portion is 1.5 mm and that of the lower portion is 3.5 mm Namely, because the lower portion of the side wall part  122  has the thickness of 3.5 mm, larger than 2.4 mm, a sufficient rigidity can be secured, and in this case, although the upper portion of the side wall part  122 , to which the load is less concentrated, has the thickness of 1.5 mm, smaller than 2.4 mm, it can obtain a sufficient rigidity. That is, according to an exemplary embodiment of the present invention, the thickness of the upper portion of the side wall part  122  is reduced because the upper portion can secure a sufficient rigidity even with that small thickness, while the thickness of the lower portion, to which the load is concentrated, is increased to obtain a sufficient rigidity. Namely, by differentiating the thicknesses of the upper portion and the lower portion of the side wall part  122 , the overall weight can be equal to or smaller than the comparison body. Thus, when the outer tub  120  is fabricated with the same amount of material, the outer tub  120  according to an exemplary embodiment of the present invention can advantageously secure better rigidity compared with the comparison body. 
         [0034]    In particular, in consideration of the increase in the weight in line with the trend that outer tubs increasingly have a large capacity, the outer tub  120  according to an exemplary embodiment of the present invention is formed with a proper difference in the thicknesses of the side wall part  122 , thus lowering the increase in the weight over the increase in the capacity, compared with the comparison body. Namely, in case of the comparison body, because the thickness of the side wall is uniform, the weight inevitably increases proportionally at a certain ratio according to an increase in the capacity, but comparatively, in case of the outer tub  120  according to an exemplary embodiment of the present invention, the increase in the weight according to the increase in the capacity can be relatively reduced by properly adjusting the thicknesses of the upper and lower portions of the side wall part  122 , so it is advantageous for the increase in the capacity. 
         [0035]    Also, because the lower portion of the side wall part  122  is heavier than the upper portion of the side wall part  122 , the center of gravity is formed at the lower portion compared with the case where the side wall part  122  is formed with a uniform thickness, and accordingly, stability can be maintained over vibrations generated when the inner tub  115  rotates. Also, because the rotation speed of the inner tub  115  can be increased owing to the improved stability, resulting in an enhancement of the washing performance. In particular, because the inner tub  115  can be rotated at a higher speed, the spin-drying performance can be improved. Meanwhile, a rib  124  may be formed on the outer tub  120  in order to secure stronger rigidity. The rib  124  may be formed to be lengthy vertically in order to effectively prevent degradation of rigidity due to the difference in thicknesses of the upper and lower portions. 
         [0036]    The side wall part according to an exemplary embodiment of the present invention may be formed to have a thickness gradually increasing toward the lower portion of the outer tub  120  from the upper portion of the outer tub  120 . Hereinafter, two examples in which the thickness increases gradually toward the lower portion of the outer tub from the upper portion of the outer tub will be proposed. 
         [0037]      FIG. 6  is a front view of an outer tub according to another exemplary embodiment of the present invention.  FIG. 7  is a sectional view of a portion ‘D’ in  FIG. 6 . 
         [0038]    With reference to  FIGS. 6 and 7 , a side wall part  222  of the outer tub  220  according to another exemplary embodiment of the present invention is formed with a slope such that the thickness increases continuously toward a lower portion from an upper portion. The upper portion of the side wall part  222  has a thickness d 1  and the lower portion of the side wall part  222  has a thickness d 2  (d 1 &lt;d 2 ). Namely, the side wall part  222  is formed such that the thickness continuously increases toward the lower portion from the upper portion (namely, from d 1  to d 2 ). In this case, the change in the thickness from d 1  to d 2  may not be necessarily linear, and the side wall part  222  of the outer tub  220  may be formed with various slopes in the continuous increases in its thickness. 
         [0039]    Because the section of the side wall part  222  is formed to have the continuously increasing thickness, the load applied to the side wall part  222  can be distributed, so the generation of an abnormal vibration or a crack potentially generated as the load is concentrated into a particular point can be prevented. Also, when the outer tub  220  is molded, it can be easily separated from the mold. 
         [0040]    With reference to  FIG. 7 , when the side wall part  222  is formed to have a uniform thickness, the center of gravity (M 0 )of the side wall part  222  will be positioned at the substantially same distance 11 from the upper and lower portions. In comparison, however, in the present exemplary embodiment of the present invention, because the thickness of the side wall part  222  increases with a slope gradually toward the lower portion from the upper portion, the center of gravity (M) is positioned at a lower side, accomplishing stability. 
         [0041]      FIG. 8  is a front view of an outer tub according to still another exemplary embodiment of the present invention.  FIG. 9  is a sectional view of a portion ‘E’ in  FIG. 8 . A description of the same or similar configuration as those of the above-described exemplary embodiments of the present invention will be omitted. 
         [0042]    The outer tub  320  according to still another exemplary embodiment of the present invention is different from the above-described exemplary embodiments in that the thickness of an outer wall part  322  of the outer tub  320  increases discontinuously toward a lower portion from an upper portion. 
         [0043]    Namely, as shown in  FIG. 9 , the side wall part  322  has a step-like section having a thickness increasing discontinuously toward the lower portion from the upper portion. Specifically, upper portion has a thickness w 1  and the lower portion has a thickness w 2  larger than w 1  (w 1 &lt;w 2 ), and the step-like section is formed such that certain intervals each having a thickness value between the thickness w 1  and the thickness w 2  are present between the upper and lower portions. Also, in this case, the center of gravity (N) is formed at a lower side than the center of gravity (N 0 ) of the case where the side wall part  322  has a uniform thickness, thus improving the stability likewise as in the foregoing exemplary embodiments. 
         [0044]    Although the preferred embodiments of the invention have been disclosed 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