Patent Publication Number: US-9422657-B2

Title: Washing machine

Description:
TECHNICAL FIELD 
     The present invention relates to washing machines, and more particularly, to a washing machine in which a tub thereof is improved for increasing a capacity of the washing machine. 
     BACKGROUND ART 
     In general, the washing machine removes various kinds of contaminants from clothes and beddings by using a softening action of detergent, friction of water flow and impacts applied to laundry caused by rotation of a pulsator or a drum. Current full automatic washing machine carries out a series of courses of washing, rinsing, spinning, and so on automatically without intermittent handling of a user. 
     It is a current trend that demands for the drum type washing machine increase gradually, which, not only enables to reduce a total height, but also does not cause problems of entangling and crumpling of the laundry compared to a pulsator type washing machine in which a washing tub rotates in an upright position. 
     A structure of the drum type washing machine will be described briefly. The drum type washing machine is provided with a body cabinet which forms an exterior of the drum type washing machine, a tub in the body cabinet supported by dampers and springs for holding washing water, and a cylindrical drum in the tub for placing the laundry therein, wherein the drum has driving power applied thereto by a driving unit for washing the laundry placed therein. 
     The drum type washing machine inevitably causes vibration due to rotation force of the drum, eccentricity of the laundry, and the like at the time the drum rotates for washing or spinning the laundry introduced to the drum, and the vibration caused by the rotation of the drum is transmitted to an outside of the drum type washing machine through the tub and the cabinet. 
     Consequently, in order to prevent the vibration from transmitting to the cabinet from the drum through the tub, springs and dampers are provided between the tub and the cabinet for buffering and damping the vibration of the tub, without fail. 
     In the meantime, the drum type washing machine is mostly installed, not independently, but in conformity with an existing installation environment (for an example, a sink environment or a built-in environment). Therefore, it is required that a size of the drum type washing machine is limited to the installation environment. 
     Thus, because change of an inside structure of the drum type washing machine is limited by the spring and damper which are provided for damping the vibration between the tub and the cabinet, and the installation environment of the drum type washing machine is limited, change of the size of the drum type washing machine itself is limited. 
     In the meantime, currently, in order to increase an amount of washing and user s convenience, many researches and developments are undergoing for increasing a washing capacity of the washing machine. However, above limitations impose many difficulties on the increasing of the size of the tub for increasing the washing capacity in an existing drum type washing machine structure. 
     Consequently, a variety of structures of washing machines are being developed for increasing the washing capacity. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     To solve the problems, an object of the present invention is to provide a washing machine having a new structure completely different from the related art washing machine. Along with this, another object of the present invention is to provide a washing machine in which a structure of the tub is improved. 
     Solution To Problem 
     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a washing machine includes a cabinet rear which forms a rear side of the washing machine, a tub for holding washing water, a drum rotatably provided to the tub, a driving unit having a rotation shaft connected to the drum, a bearing housing for rotatably supporting the rotation shaft, and a motor for rotating the rotation shaft, and a suspension assembly for supportably buffering vibration of the drum, wherein the washing machine further includes a coupling portion which is a projection from an outside circumferential surface of a rear side of the tub for fastening the tub to the cabinet rear. 
     Preferably, the coupling portion is a projection from opposite sides of an upper side of the tub in an outside circumferential surface direction of the tub. Preferably, the coupling portion further includes a coupling boss which is an extension toward a length direction of the tub from the coupling portion. 
     In the meantime, preferably, the coupling boss is extended beyond the driving unit in a rear direction of the tub. And, preferably, the coupling boss includes a plurality of reinforcing ribs for reinforcing strength of the coupling boss with respect to the coupling portion. 
     Preferably, the tub is tilted by a predetermined angle such that a front side of the tub faces upward, and the coupling boss is an extension parallel to the tub. 
     In the meantime, preferably, the cabinet rear includes a securing portion which is a projection toward the coupling boss to a position to match with the coupling boss. And, preferably, the securing portion has an end portion with a slope as much as a tilting angle of the coupling boss. And, preferably, the cabinet panel has a service panel provided at a center portion and the securing portion is on an outside of the service panel. 
     In the meantime, preferably, the suspension assembly is connected to the bearing housing. And, preferably, the washing machine further includes a rear gasket for sealing such that the washing water does not leak from a space between the tub and the driving unit and enabling the driving unit to move relative to the tub. And, preferably, the tub is supported rigidly more than the drum being supported by the suspension assembly. 
     In the meantime, the washing machine can have the tub fixedly mounted thereto, or supported by a flexible supporting structure, like a suspension assembly. Or the washing machine can be supported to an extent intermediate between the supporting and the suspension and the fixed mounting. 
     That is, the tub can be supported fixedly to an extent similar to the suspension assembly to be described later, or rigidly more than supporting with the suspension. For an example, the tub can be supported by the suspension, or by ones, such as rubber bushings, for providing a certain extent of flexibility to the tub even though the supporting is not flexible more than the suspension. 
     More examples, in which the tub is supported rigidly more than the suspension assembly, are as follows; 
     First, at least a portion of the tub can be formed as one unit with the cabinet. 
     Second, the tub can be supported connected with screws, rivets, or rubber bushings, or supported secured with welding, adhesive sealing, or the like. In this case, those connections may have rigidity greater than the suspension assembly with respect to up/down directions which are major vibration directions of the drum. 
     The tub can have a shape enlarged within a space the tub is mounted therein as far as possible. That is, the tub can be enlarged close to a wall or a frame (for an example, left or right side plate of the cabinet) that limits a left/right direction size of the space at least in left/right directions (a direction perpendicular to an axis direction of a rotation shaft in a horizontal direction). The tub can be fabricated as one unit with the left or right side wall of the cabinet. 
     Relatively, the tub can be formed closer to the wall or the frame than the drum in the left/right directions. For an example, the tub can be formed to be spaced from the wall or the frame less than 1.5 time of a space to the drum. In a state the tub is enlarged in the left/right directions thus, the drum also can be enlarged in the left/right directions. The smaller the left/right direction spaces between the tub and the drum, the drum can be enlarged the more. In reducing the left/right direction spaces between the tub and the drum, left/right direction vibration of the drum can be taken into account. The smaller the left/right direction vibration of the drum, a diameter of the drum can become the greater. Therefore, the suspension assembly which attenuates the vibration of the drum can be made to have left/right direction rigidity greater than other direction rigidity. For an example, the suspension assembly can be made to have rigidity with respect to a left/right direction deformation the greatest compared to rigidity in other directions. 
     Different from the related art, the suspension assembly can be directly connected to the bearing housing which supports the rotation shaft connected to the drum, without passed through the tub. That is, the bearing housing can include a supporting portion for supporting the rotation shaft and an extension extended therefrom, and the suspension assembly can be fastened to the supporting portion or the extension of the bearing housing. 
     In this instance, the suspension assembly can include a bracket extended in an axis direction of the rotation shaft. And, the bracket can be extended forward toward the door. 
     In the meantime, the suspension assembly can include at least two suspensions spaced in an axis direction of the rotation shaft. 
     The suspension assembly can include a plurality of suspensions which are mounted under the rotation shaft for standably supporting an object of supporting (for an example, the drum). Or, the suspension assembly can include a plurality of suspensions which are mounted over the rotation shaft for suspendably supporting an object of supporting. Those cases are of types in which the suspensions are provided only under or over the rotation shaft for supporting. 
     A center of gravity of an oscillating body including the drum, the rotation shaft, the bearing housing, and the motor can be positioned on a side of the motor with reference to at least a length direction geometric center of the drum. 
     One of the suspensions can be positioned in front or rear of the center of gravity. Moreover, the suspensions can be mounted in front and rear of the center of gravity, respectively. 
     The tub can have a rear opening. A driving unit including the rotation shaft, the bearing housing, and the motor can be connected to the tub through a flexible member. The flexible member can be made to seal such that water does not leak through the rear opening of the tub, and to enable the driving unit to move relative to the tub. The flexible member can be fabricated such that the flexible member can seal leakage of the washing water through an opening in a rear side of the tub and the driving unit can make movement relative to the tub. The flexible member may be of any material as far as the material can function as a seal and is flexible. For an example, the flexible member may be formed of a gasket material like the front gasket. In this case, for convenience s sake, the flexible member may be called as a rear gasket with reference to the front gasket. The rear gasket can be connected to the driving unit in a state the rear gasket is limited not to rotate at least in a rotation direction of the rotation shaft. As an embodiment, the rear gasket can be connected to the rotation shaft directly, or to the extension of the bearing. 
     A portion of the driving unit positioned in front of a connection portion to the rear gasket so as to be vulnerable to exposure to the washing water in the tub can be made to be prevented from corrosion by the washing water. For an example, the portion may be coated, or a front surface thereof may be covered with an additional component (for an example, a tub back to be described late) of plastic. Parts of the driving unit formed of metal can be prevented from corrosion by preventing the parts from direct exposure to the water. 
     Along with this, different from the embodiment, the cabinet may not be included to the washing machine. For an example, in a case of a built-in washing machine, a space the washing machine is to be installed therein may be provided, not by the cabinet, but by a wall structure. That is, the washing machine can be fabricated in a shape with does not include the cabinet which forms an exterior, independently. However, in this case too, the front frame can be required for a front exterior. 
     Advantageous Effects of Invention 
     The washing machine of the present invention has following advantageous effects. 
     The modification of a shape of the tub taking movement of the drum into account permits to prevent the drum from interfering with the tub. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are included to provide further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiments of the disclosure and together with the description serve to explain the principle of the disclosure. 
       In the drawings: 
         FIG. 1  illustrates an exploded perspective view of a washing machine in accordance with a preferred embodiment of the present invention. 
         FIGS. 2 and 3  illustrate perspective views of tub fronts of a washing machine in accordance with a preferred embodiment of the present invention, respectively. 
         FIG. 4  illustrates a rear perspective view of a tub rear of a washing machine in accordance with a preferred embodiment of the present invention. 
         FIG. 5  illustrates a suspension of a washing machine in accordance with a preferred embodiment of the present invention. 
         FIG. 6  illustrates a side view of an assembly of a tub and a suspension assembly of a washing machine in accordance with a preferred embodiment of the present invention. 
         FIG. 7  illustrates a partial section of a rear side of a tub rear of a washing machine in accordance with a preferred embodiment of the present invention. 
         FIG. 8  illustrates a partial section showing a coupling state of a tub rear and a cabinet rear of a washing machine in accordance with a preferred embodiment of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Reference will now be made in detail to the specific 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. 
     In describing the present invention, names of elements are defined taking functions thereof into account. Therefore, it is required to understand that the names do not limit the elements technically. Moreover, the names of the elements may be called differently in this field of art. 
       FIG. 1  illustrates an exploded perspective view of a washing machine in accordance with a preferred embodiment of the present invention. 
     Referring to  FIG. 1 , the washing machine has a tub  10  fixedly secured to a cabinet. The tub includes a tub front  100  which forms a front portion thereof and a tub rear  120  which forms a rear portion thereof. The tub front  100  and the tub rear  120  are fastened together with screws for forming a space for placing a drum therein. The tub also includes a tub back  130  which forms a rear surface thereof. The tub back  130  is connected to the tub rear  120  with a rear gasket  250 . The rear gasket  250  is formed of a flexible material for preventing vibration from transmitting to the tub rear  120  from the tub back  130 . 
     The cabinet  60  forms an exterior of the washing machine. The cabinet  60  has a cabinet front (not shown), a cabinet rear  620 , a cabinet left  640 , a cabinet right  640 , a cabinet right  630 , a cabinet top (not shown), and a cabinet base  600 . 
     The tub rear  120  has a rear surface  128 . The rear surface  128  of the tub rear  120 , the tub back  130 , and the rear gasket  250  form a rear wall surface of the tub  10 . The rear gasket  250  is sealably connected to the tub back  130  and the tub rear  120  respectively for preventing the washing water from leaking from the tub  10 . The tub back  130  vibrates together with the drum  30  when the drum  30  rotates. In order to prevent the tub back  130  from interfering with the tub rear  120  at the time the tub back  130  vibrates, the tub back  130  is spaced from the tub rear  120 , adequately. Since the rear gasket  250  is formed of a flexible material, the rear gasket  250  allows the tub back  130  to make relative motion without interference with the tub rear  120 . The rear gasket  250  may have a corrugated portion  252  (See  FIG. 4 ) which can be extended adequately for allowing the relative motion of the tub back  130 . 
     A foreign matter getting in preventive member  200  is connected to a front of the tub front  100  for preventing foreign matters from entering between the tub  10  and the drum  30 . The foreign matter getting in preventive member  200  is formed of a flexible material, and fixedly mounted to the tub front  100 . The foreign matter getting in preventive member  200  may be formed of a material the same with the rear gasket  250 . 
     The drum  30  includes a drum front  300 , a drum center  320 , and a drum back  340 . The drum front  300  has a laundry opening for introducing the laundry to the drum  30 . Ball balancers  310  and  330  are mounted to a front portion and a rear portion of the drum  30 , respectively. The drum back  340  is connected to a spider  350 , and the spider  350  is connected to a rotation shaft  351 . The drum  30  rotates in the tub by rotation force transmitted thereto through the rotation shaft  351 . 
     The rotation shaft  351  is passed through the tub back  130  and connected to the motor in a direct manner. More specifically, a rotor (not shown) of the motor and the rotation shaft  351  are connected, directly. There is a bearing housing  400  coupled to the rear surface  128  of the tub back  130 . The bearing housing  400  rotatably supports the rotation shaft  351  between the motor and the tub back  130 . 
     A stator is fixedly mounted to the bearing housing  400 . The rotor is positioned around the stator. As described before, the rotor is directly connected to the rotation shaft  351 . The motor, being an outer rotor type motor, is connected to the rotation shaft  351 , directly. 
     The bearing housing  400  is supported on a cabinet base  600  through a suspension assembly  40  (See  FIG. 5 ). The suspension assembly  40  includes three spring cylinder dampers  500 ,  510  and  520  and two cylinder dampers  530  and  540  for supporting in front/rear directions in a tilted positions. The suspension assembly  40  is connected to the cabinet base  600 , not fixedly perfectly, but to allow a certain extent of elastic deformation to allow the drum  30  to move in front/rear and left/right directions. 
     That is, the suspension assembly  40  is elastically supported to allow a certain extent of rotation of the suspension assembly  40  in front/rear and left/right directions with respect to a supporting point at which the suspension assembly  40  is connected to the base  600 . In order to make such elastic supporting available, the vertical suspensions may be mounted to the base  600  with rubber bushings disposed therebetween, respectively. Of the suspensions, it can be configured that the vertical suspensions elastically buffer vibration of the drum, and the tilted suspensions dampens the vibration of the drum  30 . That is, it can be configured that, of a vibration system having springs and damping means, ones mounted in vertical positions serve as springs and ones mounted in a tilted positions serve as damping means. 
     The tub  10  is fixedly mounted to the cabinet except the tub back  130 , and the vibration of the drum  30  is buffered and supported by the suspension assembly  40 . It can be said that supporting structures for the tub  10  and the drum  30  are separated from each other actually, such that the tub  10  does not vibrate even if the drum  30  vibrates. 
     Respective parts will be described in detail. 
       FIGS. 2 and 3  disclose the tub front  100 . The tub front  100  has a donut shaped vertical front surface at a front side of a cylindrical surface which is a portion of a sidewall of the tub  10 . The front surface has a laundry opening  100   a  for introduction of the laundry. A rear side of the cylindrical surface is opened the same as an opening of the cylinder of the tub front  100 , and has a plurality of fastening holes  110 . The fastening holes  110  are fastened to fastening holes  127  (See  FIG. 4 ) in the tub rear  120  matched thereto, respectively. 
     A rim portion  101  is extended forward from an inside circumferential surface of a front surface  112  of the tub front  100 . The rim portion  101  has a width which becomes the smaller as the rim portion  101  goes from an upper side to a lower side the more. There may not be the rim portion  101  formed on a lower side of an inner edge of the front surface  112 , actually. 
     The rim portion  101  has a water supply inlet  104 , a hot air inlet  103  to be used for drying, a circulating water inlet  106  for inlet of washing water circulated by a circulating pump, and a steam inlet  105  for introduction of steam. 
     Since the washing machine of the present invention has vibration of the tub  10  reduced significantly, connections of a water supply structure, such as the water supply hose for supplying washing water, a structure for drying, such as drying duct, a structure for supplying steam, a structure for supplying the circulating water, and so on can be held in position, securely. 
     The hot air inlet  103  is an upward rectangular shaped extension from the rim portion  101 , substantially. The hot air inlet  103  is required for a washing and drying machine, and may not be required for a washing machine which has no drying function. 
     Since the water supply inlet  104 , the hot air inlet  103  and so on are formed in the front portion of the tub front  100 , supply of the washing water, the hot air and so on are made at the front side of the tub  10 . 
     The water supply inlet  104  and so on can be positioned in front of a front end of the drum  30  which is housed in the tub  10 . Accordingly, the washing water, the hot air and so on can be introduced to the drum  30  directly through the laundry opening provided for laundry in/out. Since fluids which are supplied for treating the laundry, such as the washing water, the hot air and so on, can be introduced to the drum  30  directly, effective treatment of the laundry is possible. 
     Moreover, in a case detergent is supplied together with the washing water which is supplied through detergent box, if the detergent is introduced to the drum  30  directly, consumption of the detergent can be reduced, enabling to reduce an amount of the washing water, accordingly. 
     And, a problem of contamination of a bottom of the tub  10  by deposition of detergent sediments can be reduced. Furthermore, the water supply from the front of the tub  10  can have an effect of washing door glass (not shown). 
     Even if the hot air is supplied from the front of the tub  10 , if the hot air is supplied through a vertical surface of the tub front  100 , since a flow of the hot air undergoes two times of bending to form a ‘⊂’-shape (a ‘⊂’-shaped complicate flow is formed as the hot air introduced into the tub  10  is bent downward at a front of the tub  10  and bent forward of the tub  10  again), the flow of the hot air can be poor. However, if the hot air inlet  103  is formed in the rim portion  101  of the tub front  100 , the flow of the hot air can be smooth since the hot air flow is required to bend only once, vertically. 
     The water supply inlets  104  and so on are positioned above a center point of the drum. The washing water and so on are supplied to the drum  30  from an upper side of the front of the drum. If, different from this, if it is required to supply the washing water and so on to the drum  30  from a lower side of the front of the drum, the rim portion  101  of the tub front  100  may be formed at the lower side of the front surface  112 , accordingly. If it is required to supply the washing water and so on to the drum, not from the upper or lower side, but from a left or right side of the drum, the rim portion  101  can be formed in the vicinity of a center portion of an inside edge of the front surface  112 , accordingly. That is, a shape of the rim portion  101  can vary with a direction of supply of the fluids. 
     In a front edge of the rim portion  101 , there is a coupling portion  102  for coupling the foreign matter getting in preventive member  200  thereto. The coupling portion  102  is a forward extension from a front end of the rim portion  101  to form a small cylindrical surface, substantially. The small cylindrical surface has a rib  102   a  formed on an outside circumferential surface of the small cylindrical surface. 
     The foreign matter getting in preventive member  200  is coupled to the coupling portion  102  as the coupling portion  102  is placed in the foreign matter getting in preventive member  200 . Accordingly, the foreign matter getting in preventive member  200  has a groove (not shown) for placing the small cylindrical surface having the rib  102   a  formed therein. 
     The tub front  100  is fixedly connected to the cabinet front (not shown). For this fixed connection of the tub front  100 , fastening bosses  107   a ,  107   b ,  107   c  and  107   d  are formed on the front surface of the tub front  100  around the rim portion  101 , substantially. After positioning the cabinet front (not shown) in a state the tub front  100  is mounted, the cabinet front (not shown) is fastened to the tub front  100  by fastening screws from a front side to a rear side. 
       FIG. 3  illustrates a perspective view of the tub front  100  seen from a back side thereof. The steam inlet  105  can be connected to a steam hose. The steam inlet  105  has a steam guide  105   a  for guiding the steam introduced thereto to an inside of the drum. The circulating water inlet  106  has a circulating water guide  106   a  for guiding the circulating water introduced to the circulating water inlet  106  to the inside of the drum. The steam inlet  105 , the circulating water inlet  106 , the steam guide  105   a  and the circulating water guide  106   a  are formed as one unit with the tub front  100 . The tub front  100  of plastic is injection molded together with the steam inlet  105  and so on as portions of the tub front  100 . 
     The tub front  100  is coupled to the tub rear  120  to form a space for housing the drum  30 . The tub front  100  and the tub rear  120  are fastened with screws. For this screw fastening, the tub front  100  has a plurality of screw fastening holes  110  formed along a circumference of a rear portion thereof. 
       FIG. 4  illustrates the tub front  100 , the tub rear  120 , the tub back  130 , and the rear gasket  250  assembled together. 
     The tub rear  120  is cylindrical to surround the drum  30 , and has an opened front opened as it is, and a donut shaped rear surface  128 . The front is sealably coupled to the tub front  100 . The rear surface of the tub rear  120  has a diameter adequately greater than the outside diameter of the tub back  130 , so that a gap is formed enough to prevent the tub back  130  from interfering with the rear surface of the tub rear  120  even if the tub back  130  vibrates. 
     And, between the rear surface of the tub rear  120  and the tub back  130 , there is the rear gasket  250  connected thereto. The rear gasket  250  seals between the rear surface of the tub rear  120  and the tub back  130 . The rear gasket  250  has a corrugated portion  252  having an adequate flexibility for not interfering with the vibration of the tub back  130 . 
     The tub rear  120  has a hot air outlet  121  on one side for the washing and drying machine. It is natural that the hot air outlet  121  is not required if the washing machine is not the washing and drying machine, but a washing machine only for washing. 
     In the meantime, on undersides of the tub front  100  and the tub rear  120 , there are additional structures for securing and supporting the tub  10  on the base. 
       FIG. 5  illustrates a perspective view showing a suspension assembly  40  mounted on the base  600 .  FIG. 6  illustrates a side view of an assembly of the tub  100  and  120 , the bearing housing  400 , and the suspension assembly  40 . 
     The bearing housing  400  includes a bearing supporting portion  401  for supporting the bearings. On a front side of the bearing housing  400 , there is a tub back fastening portion  407  formed thereon. On a rear side of the bearing housing  400 , there is a stator fastening portion  402  formed thereon. 
     In this instance, the suspension assembly  40  includes the bearing housing  400 , a first tilted bracket  431  and a second tilted bracket  430 , and a first suspension bracket  450  and a second suspension bracket  440 . 
     There are a first extension  406   a  and a second extension  406   b  which are extensions from the bearing housing  400  in a radial direction to left and right sides thereof. The first extension  406   a  and the second extension  406   b  have a first tilted bracket  431  and a second tilted bracket  430  connected thereto, respectively. The first tilted bracket  431  and the second tilted bracket  430  have the first suspension bracket  450  and the second bracket  440  connected thereto, respectively. 
     In this instance, the first extension  406   a , the first tilted bracket  431 , the first suspension bracket  450  and the second extension  440 , the second tilted bracket  430 , the second suspension bracket  440  are symmetry. In this instance, the first, and second tilted brackets  431  and  430  serves to balance a center of gravity of the drum when laundry is introduced to the drum, and as mass in a vibration system in which the drum  30  vibrates. 
     The suspension assembly  40  may include a first spring cylinder damper  520 , a second spring cylinder damper  510 , a third spring cylinder damper  500  which are arranged in a vertical direction for vertical direction buffering, and a first cylinder damper  540  and a second cylinder damper  530  arranged in a tilted position for front/rear direction buffering. 
     In this instance, of the first spring cylinder damper  520 , the second spring cylinder damper  510  and the third spring cylinder damper  500 , one may be arranged on a rear side and two may be arranged on left/right sides on a front side of a center of the base  600 . And, the first cylinder damper  540  and the second cylinder damper  530  may be arranged in a front/rear direction on left/right sides with reference to the center in a tilted position. 
     In detail, the first cylinder damper  540  is connected between the first suspension bracket  450  and the base  600 . The second spring cylinder damper  510  is connected between the second suspension bracket  440  and the base  600 . The third spring cylinder damper  500  is connected between the bearing housing  400  and the base  600 . 
     The first cylinder damper  540  is arranged between the first suspension bracket  450  and a rear side of the base in a tilted position, and the second cylinder damper  530  is arranged between the second suspension bracket  440  and the rear side of the base in a tilted position. 
     That is, the third spring cylinder damper  500  is arranged at a center of a rear side, and the first cylinder damper  540  and the second spring cylinder damper  510  are arranged on left/right sides of a front side. The first cylinder damper  540  and the second spring cylinder damper  510  are positioned on opposite sides of the third spring cylinder damper  500 . That is, the spring dampers  500 ,  510  and  520  are arranged symmetry with the cylinder dampers  530  and  540  in left/right directions. 
     In the meantime, the tub  10  (specifically, the tub rear  120 ) of the washing machine of the present invention is supported rigidly more than the drum  30 . To do this, the tub  10  can be supported on the cabinet base  600  by an additional supporter (not shown) and fixedly secured to the cabinet front (not shown) and the cabinet rear  620 , additionally. 
     A state of fixation of the tub rear  120  to the cabinet rear  620  will be described with reference to the attached drawings. 
       FIG. 7  illustrates a partial section of a rear side of a tub rear of a washing machine in accordance with a preferred embodiment of the present invention, and  FIG. 8  illustrates a partial section showing a coupling state of a tub rear and a cabinet rear of a washing machine in accordance with a preferred embodiment of the present invention. 
     In the meantime, the tub rear  120  and the cabinet rear  620  have fastening structures at predetermined portions thereof respectively for fastening the tub rear  120  to the cabinet rear  620 . 
     The tub rear  120  has coupling portions  124   a  and  124   b  on a rear side projected outward from a body of the tub rear  120  for coupling to the cabinet rear  620 , respectively. That is, the coupling portions  124   a  and  124   b  are formed on an outer side of an outside circumferential surface of the tub rear  120 . It is preferable that one pair of the coupling portions are provided on left/right sides of an upper side of the tub rear. 
     In the meantime, the coupling portions  124   a  and  124   b  have coupling bosses  126   a  and  126   b  projected parallel to the tub rear  120 , respectively. The tub  10  is secured, not in a horizontal position, but in a tilted position such that a front side of the tub  10  is higher than the rear side of the tub  10 . In addition to this, there are a plurality of reinforcing ribs  125   a  and  125   b  (See  FIGS. 4 and 6 ) between the coupling portions  124   a  and  124   b  and the coupling bosses  126   a  and  126   b  for reinforcing strength of the coupling bosses  126   a  and  126   b.    
     The coupling bosses  126   a  and  126   b  respectively projected from the coupling portions  124   a  and  124   b  are projected beyond a rear side of the bearing housing  400  positioned on a rear side of the tub  10  by predetermined distances T, respectively. The coupling bosses  126   a  and  126   b  are projected beyond a rear side of the bearing housing  400  by predetermined distances T thus because the tub  10  is secured more rigidly than the drum  30  and the bearing housing  400  vibrates in association with the vibration of the drum  30 . That is, a space is formed between the cabinet rear  620  having the coupling bosses  126   a  and  126   b  coupled thereto and the bearing housing  400  for securing a space for the bearing housing  400  to vibrate therein. In this instance, in rear of the bearing housing  400 , a motor may be mounted. Therefore, it is preferable that the coupling bosses  126   a  and  126   b  are formed extended more than the motor, respectively. 
     In the meantime, the cabinet rear  620  forms a rear side of the washing machine. The cabinet rear  620  has a service panel (not shown) at a center fastened so as to be able to open/close for maintenance of the washing machine separate from the cabinet rear  620 . The cabinet rear  620  has securing portions  622   a  and  622   b  on an upper side spaced from the service panel for fastening to the coupling bosses  126   a  and  126   b  on the tub rear  120 , respectively. 
     The securing portions  622   a  and  622   b  are projections toward an inside of the cabinet rear  620 , i.e., toward the coupling bosses  126   a  and  126   b  on the tub rear  120 , respectively. And, the securing portions  622   a  and  622   b  have end portions sloped by predetermined angles DA as much as the tilting angles of the coupling bosses  126   a  and  126   b  on the tub rear  120 , respectively. In this instance, it is preferable that the predetermined angles of the end portions of the securing portions  622   a  and  622   b  are the same with the tilting angles of the tub  10 . Eventually, the tub rear  120  positioned tilted by the predetermined angle and the cabinet rear  620  and the cabinet rear  620  mounted in a vertical position can be fastened together, closely. 
     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 the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.