Abstract:
A washing machine and a method for manufacturing the same are disclosed. A washing machine includes a casing that defines an outer appearance of the washing machine and an outer tub in the casing that is configured to receive water. A supporting rod is coupled with the casing, and a suspension is coupled with the outer tub, the supporting rod being inserted in the suspension. The suspension is configured to move bi-directionally along the supporting rod as the outer tub vibrates to mitigate vibration of the outer tub, and the suspension includes a frictional part configured to contact the supporting rod. The suspension is configured to apply a lubricating material to a portion of the supporting rod that is brought in contact, during the vibration of the outer tub, with the frictional part of the suspension.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    Pursuant to 35 U.S.C. §119(a), this application claims the benefit of an earlier filing date and right of priority to Korean Patent Application No. 10-2013-0133141, filed on Nov. 4, 2013 in the Korean Intellectual Property Office, the contents of which are incorporated herein by reference in their entirety. 
       TECHNICAL FIELD 
       [0002]    The present application relates to a washing machine and a method of manufacturing the same, and particularly, to a washing machine that reduces vibration that occurs while the washing machine is in operation. 
       BACKGROUND 
       [0003]    Typically, a washing machine is an apparatus that washes objects using a softening effect of detergent, a water flow generated as the washing tub or washing blades rotate, and an impact exerted by the washing blades. A washing machine performs washing, rinsing, and/or dehydrating to remove contaminants from the objects to be washed (hereinafter, referred to as “laundry”) through an interaction between the detergent and water. 
       SUMMARY 
       [0004]    In one aspect, a washing machine includes a casing that defines an outer appearance of the washing machine; an outer tub provided in the casing and configured to receive water; a supporting rod coupled with the casing; and a suspension coupled with the outer tub, the supporting rod being inserted in the suspension. The suspension is configured to move bi-directionally along the supporting rod as the outer tub vibrates to mitigate vibration of the outer tub, and the suspension includes a frictional part configured to contact the supporting rod. The suspension is configured to apply a lubricating material to a portion of the supporting rod that is brought in contact, during the vibration of the outer tub, with the frictional part of the suspension. 
         [0005]    Implementations may include one or more of the following features. In some implementations, the supporting rod includes a first frictional portion configured to contact the frictional part of the suspension based on the outer tub being stationary; a second frictional portion that is brought in contact with the frictional part of the suspension based on the outer tub vibrating; and a third portion corresponding to a lower side of the second frictional portion. The suspension is configured to apply the lubricating material over the first frictional portion and the second frictional portion. 
         [0006]    In some implementations, the second frictional portion of the supporting rod includes a peak frictional part that is brought in contact with the frictional part of the suspension based on an amplitude of movement of the suspension along the supporting rod reaching a peak amplitude due to the vibration of the outer tub, and the suspension is further configured to, based on an external force greater than a predetermined force being applied to move the suspension along the supporting rod beyond the peak amplitude, expose the peak frictional part of the supporting rod to an outside of the suspension at an upper side of the frictional part of the suspension. 
         [0007]    In some implementations, the suspension includes a storage unit that is located at the upper side of the frictional part of the suspension and that defines a space configured to store the lubricating material between the frictional part of the suspension and the supporting rod, and, based on the external force greater than the predetermined force being applied to move the suspension along the supporting rod beyond the peak amplitude, the peak frictional part of the supporting rod is pushed to an upper side of the storage unit and exposed to an outside of the suspension. 
         [0008]    In some implementations, the second frictional portion of the supporting rod includes a normal frictional part N which corresponds to other portions of the supporting rod except the peak frictional part of the supporting rod, and on which the lubricating material is applied from the storage unit. 
         [0009]    In another aspect, a washing machine includes a casing that defines an outer appearance of the washing machine, an outer tub provided in the casing and configured to receive water, a supporting rod coupled with the casing, and a suspension coupled with the outer tub, the supporting rod being inserted in the suspension. The suspension is configured to move bi-directionally along the supporting rod as the outer tub vibrates to mitigate vibration of the outer tub, and the suspension is configured to apply a lubricating material to a portion of the supporting rod that contacts the suspension. The suspension is configured to move bi-directionally along the supporting rod while the suspension is in frictional contact with the portion of the supporting rod on which the lubricating material is applied. 
         [0010]    In some implementations, the suspension includes an air cap configured to move along the supporting rod as the outer tub vibrates, and a first elastic member is disposed in the air cap and is configured to elastically support the air cap at an upper end thereof. A base is disposed at an end of the supporting rod and configured to support a lower end of the first elastic member, and the base is configured to be insertable into the air cap. 
         [0011]    In some implementations, the first elastic member is configured to exert a force such that an inner surface of the air cap is forced apart from the base. 
         [0012]    In some implementations, the air cap includes a cylindrical part that defines a space configured to accommodate the first elastic member, a frictional part located at an end of the cylindrical part and configured to surround the supporting rod to create friction, a storage unit surrounding the supporting rod and forming a space configured to store the lubricating material between the supporting rod and the storage unit. 
         [0013]    In some implementations, the storage unit is located at an upper side of the frictional part of the cylindrical part of the air cap and configured to supply the lubricating material to a space between the frictional part of the cylindrical part of the air cap and the supporting rod. 
         [0014]    In some implementations, the air cap includes an air vent configured to discharge air located between an inner surface of the air cap and the base. 
         [0015]    In some implementations, the base is configured to move along the supporting rod to compress air located in the air cap. 
         [0016]    In some implementations, the washing machine further includes a second elastic member configured to expand the base to narrow a gap between an inner surface of the air cap and the base. 
         [0017]    In another aspect, a washing machine includes a casing that defines an outer appearance of the washing machine, and an outer tub is provided in the casing and configured to receive water. An air cap is provided at an outer circumference of the outer tub and includes a space configured to accommodate air. A supporting rod is coupled with the casing and is configured to guide movement of the air cap as the outer tub vibrates, the air cap defining a space configured to store a lubricating material between the air cap and the supporting rod to block air located in the air cap from being discharged between the supporting rod and the air cap as the air cap moves. 
         [0018]    In some implementations, the washing machine further includes a base provided in the supporting rod and configured to be moved by the supporting rod to compress air located in the air cap. 
         [0019]    In some implementations, the air cap includes an air vent configured to discharge air from between the an inner surface of the air cap and the base as the base moves towards a peak position at which the base is maximally inserted in the air cap by the vibration of the outer tub. 
         [0020]    In some implementations, the air cap includes a frictional part that surrounds the supporting rod and that is configured to create a frictional force with the supporting rod, and the air cap is configured to apply the lubricating material between the supporting rod and the frictional part based on the base reaching the peak position. 
         [0021]    In some implementations, the washing machine further includes a first elastic member provided between the base and the air cap and elastically supporting the air cap. 
         [0022]    In some implementations, the washing machine further includes a second elastic member configured to expand the base to narrow a gap between an inner surface of the air cap and the base. 
         [0023]    In some implementations, a frictional member brought in frictional contact with the supporting rod is provided in the storage unit, the frictional member being soaked in the lubricating material. 
         [0024]    In another aspect, a method of manufacturing a washing machine is disclosed. The washing machine includes a casing that defines an outer appearance of the washing machine, and an outer tub is provided in the casing configured to receive water. A supporting rod is coupled with the casing, and a suspension is coupled with the outer tub, wherein the supporting rod is configured to be insertable into the suspension, and the suspension is configured to move bi-directionally along the supporting rod as the outer tub vibrates to mitigate vibration of the outer tub. The suspension includes a frictional part configured to contact the supporting rod. The method of manufacturing the washing machine includes inserting the supporting rod in the frictional part of the suspension. The method also includes applying a force to expose, to an outside of the suspension, a portion of the supporting rod that contacts the frictional part of the suspension based on the outer tub reaching a maximum vibration amplitude within a preset vibration range of the outer tub, and applying a lubricating material to the exposed portion of the supporting rod. 
         [0025]    The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. The description and specific examples below are given by way of illustration only, and various changes and modifications will be apparent. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    In the drawings: 
           [0027]      FIG. 1  is a cross-sectional view illustrating examples of main components of a washing machine according to some implementations; 
           [0028]      FIG. 2  is a partial perspective view illustrating an example configuration in which a suspension is added to the outer tub shown in  FIG. 1 ; 
           [0029]      FIG. 3  is a cross-sectional view taken along line B-B of  FIG. 2 ; 
           [0030]      FIG. 4  is a lower side view illustrating the base shown in  FIG. 3 ; 
           [0031]      FIGS. 5A ,  5 B, and  5 C are views illustrating an example of an operational relationship of a suspension according to some implementations; and 
           [0032]      FIG. 6  is a flowchart illustrating an example of a method of manufacturing a washing machine according to some implementations. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    The present disclosure relates to a washing machine and a method of manufacturing the same, and particularly, to a washing machine that may effectively reduce vibration that occurs while the washing machine is in operation. The washing machine may effectively reduce vibration even when the vibration of the outer tub varies. In some implementations, the washing machine may also have an increased capacity of the outer tub. In some implementations, the washing machine may have reduced noise and increased durability and stability. 
         [0034]    The washing machine may reduce vibration of outer tub, and may, in some implementations, enable increased durability and stability and reduced noise. The washing machine may also reduce vibration of the outer tub in the vibration state. 
         [0035]    A washing machine includes a casing forming its outer appearance, an outer tub hung in the casing, and an inner tub rotatably provided in the outer tub. The washing machine further includes a suspension to reduce vibration of the outer tub that occurs as the inner tub and/or pulsator rotates. 
         [0036]    A washing machine may have a suspension structured to decrease the vibration that occurs from the outer tub using, e.g., elasticity/restoration force of spring and viscosity of fluid. A washing machine may have its suspension designed specifically for a normal vibration state, but may not provide satisfactory vibration reduction in the transient vibration state. In other words, although such suspension may respond to vibration in a normal state where the outer tub vibrates within a constant amplitude range, the suspension may be less effective during a transient vibration state in which the outer tub vibrates with a larger amplitude than that in the normal state. On the other hand, if a suspension system is designed to operate for the transient vibration state where a large amplitude occurs, the suspension system may show a deteriorated vibration reduction when operating in the normal vibration state with a relatively smaller amplitude. 
         [0037]    The present disclosure describes techniques in which a washing machine may provide effective vibration mitigation for both a normal vibration state and a transient vibration state. Advantages and features of a washing machine according to the present disclosure will be more clearly understood from implementations described below with reference to the accompanying drawings. However, implementations are not limited to the following examples and may include various different forms. The implementations described in the following are provided as illustrative examples. Wherever possible, the same reference numbers will be used throughout the specification to refer to the same or like parts. 
         [0038]    Hereinafter, some implementations are described in detail with reference to the accompanying drawings. 
         [0039]      FIG. 1  illustrates examples of main components of a washing machine according to some implementations.  FIG. 2  illustrates a configuration in which a suspension is added to the outer tub shown in  FIG. 1 .  FIG. 3  is a cross-sectional view taken along line B-B of  FIG. 2 .  FIG. 4  is a lower side view illustrating the base shown in  FIG. 3 . 
         [0040]    Referring to  FIGS. 1 to 4 , according to some implementations, a washing machine includes a casing  1  forming its outer appearance; an outer tub  2  provided in the casing  1  to contain washing water; a supporting rod  15  coupled with the casing  1 ; and a suspension  30  coupled with the outer tub  2 . The supporting rod  15  is inserted into the suspension  30 . The suspension  30  moves to-and-fro along the supporting rod  15  as the outer tub  2  vibrates to mitigate the vibration of the outer tub  2 . A lubrication (e.g., slideway oil) is applied to a portion of the supporting rod  15  that contacts the suspension  30 . The suspension  30  moves to-and-fro while in friction with the slideway oil-applied portion. 
         [0041]    The supporting rod  15  is connected to the casing  1 . The supporting rod  15  is connected with the suspension  30 . The suspension  30  absorbs the vibration of the outer tub  2 . The suspension  30  generates frictional forces against the supporting rod  15  at a plurality of portions. The supporting rod  15  may contact a frictional member. A lubrication (e.g., slideway oil) is applied on the supporting rod  15 . The slideway oil creates a viscous frictional force. The suspension  30  is mounted in the outer tub  2  and vibrates alongside the outer tub  2 . The suspension  30  removes the vibration of the outer tub  2 . 
         [0042]    The casing  1  forms an outer appearance of the washing machine. The washing machine includes a control panel  11  having manipulation keys for receiving various control commands from the user and a display for displaying information on the operational state of the washing machine and providing a user interface and a door  7  rotatably provided in the casing  1  to open and close an entrance/exit hole (not shown) through which the laundry is entered and exited. 
         [0043]    The outer tub  2  containing washing water is provided to be hung in the casing  1  by the supporting rod  15 . An inner tub  3  is rotatably provided in the outer tub  2  to contain the laundry. A pulsator  4  is rotatably provided on the bottom of the inner tub  3 . The inner tub  3  includes a plurality of perforations through which washing water passes. 
         [0044]    Any casing may be included in the casing defined herein as long as the casing forms an outer appearance of the washing machine. In particular, the casing may be a rigid body motionlessly fixed to allow an end of the supporting rod  15  hanging the outer tub  2  in the casing to be fixed to the casing. The casing to be hereinafter mentioned is merely an example of a configuration forming the outer appearance of the washing machine, and it should be appreciated that the casing defined in the claims is not limited in range thereto. 
         [0045]    The casing  1  includes a main body  12  with an upper side opened and a top cover  14  provided at an upper side of the main body  12  and having an entrance/exit hole at substantially the middle thereof to permit entrance/exit of the laundry. 
         [0046]    An end of the supporting rod  15  may be fixed to either the main body  12  or the top cover  14 . A supporting means (not shown) may be further provided to allow the supporting rod  15  to pivot as the outer tub  2  vibrates. 
         [0047]    An end of the supporting rod  15  is connected with the casing  1 , and another end thereof is connected with the outer tub  2  by the suspension  30 . The suspension  30  connects the supporting rod  15  with the outer tub  2  and reduces the vibration of the outer tub  2  that occurs while the washing machine is in operation. 
         [0048]    The suspension  30  may include an air cap  31  through which the other end of the supporting rod  15  passes and which is fixed to an outer circumferential lower part of the outer tub  2  to be coupled with the outer tub  2  and a base  37  disposed in the air cap  31  to attenuate the vibration of the outer tub  2  by a frictional force generated in association with at least one of the air cap  31  and the supporting rod  15  as the outer tub  2  vibrates. Meanwhile, in case the outer tub  2  significantly vibrates, e.g., when the rotational speed of the inner tub  3  is drastically increased or when the inner tub  3  rotates at high speed with the laundry unevenly placed, the lower-directional displacement of the air cap  31  is sharply increased. An elastic member is elastically deformed as the lower-directional displacement of the air cap  31  is increased, thus assisting in attenuating vibration. 
         [0049]    In some implementations, a spring, which is one possible example of first elastic member  35 , is inserted into the supporting rod  15 . The suspension  30  may further include the base  37  disposed at the other end of the supporting rod  15  to support the first elastic member  35 . Since an end of the first elastic member  35  (e.g., a spring) is supported by the base  37  and the other end thereof is restricted by the air cap  31 , as the lower-directional displacement of the air cap  31  increases, the air cap  31  pushes the first elastic member  35  (e.g., a spring) downwards and the first elastic member  35  is compressed. 
         [0050]    In contrast, as the upper-directional displacement of the outer tub  2  increases, the restoration force of the first elastic member  35  (e.g., a spring) acts to push the air cap  31  upwards, so that the air cap  31  interworks with the outer tub  2  while in tight contact with the outer tub  2 . Such structure allows the air cap  31  and the outer tub  2  to be coupled with each other without necessarily requiring a separate coupling member for fixing the air cap  31  to the outer circumference of the outer tub  2 . 
         [0051]    The air cap  31  is shaped as substantially a cylinder. The air cap  31  is rendered to contain compressed air by the base  37 . The base  37  is disposed at a lower end of the air cap  31 . A storage unit  33  to be described below is formed at an upper end of the air cap  31 . 
         [0052]    The base  37  is mounted to the supporting rod  15 . The base  37  moves alongside the supporting rod  15 . The base  37  is inserted in the air cap  31 . The base  37  pressurizes a first elastic member  35 . A second elastic member  39  to be described below is inserted in the base  37 . 
         [0053]    The first elastic member  35  exerts a force in a direction in which an inner surface of the air cap  31  is spaced apart from the base  37 . The first elastic member  35  exerts an elastic force in a direction in which the base  37  is pushed away. The first elastic member  35  may be a coil spring. The base  37  penetrates the first elastic member  35 . 
         [0054]    The air cap  31  includes a cylindrical part  34  forming a space for accommodating the first elastic member  35 ; a frictional part  32  formed at an end of the cylindrical part  34  to surround the supporting rod  15  to create friction; and a storage unit  33  surrounding the supporting rod  15  and forming a space for storing lubrication material (e.g., a slideway oil) between the supporting rod  15  and the storage unit  33 . 
         [0055]    The base  37  is inserted in the cylindrical part  34 . The cylindrical part  34  has a bottle neck part  38  at an upper end thereof. The frictional part  32  and the storage unit  33  are formed in the bottle neck part. The bottle neck part supports the outer tub  2 . The bottle neck part is stuck in the outer circumference of the outer tub  2 . The frictional part  32  abuts the supporting rod  15 , and thus, a kinetic frictional force acts between the frictional part  32  and the supporting rod  15  as the outer tub  2  vibrates. A frictional member is disposed in the storage unit  33 . The frictional member may be formed of fabric such as felt. The frictional member may be soaked in the slideway oil. The slideway oil is a fluid used to ease the motion of sliding surface-contact structures. Too high viscosity of the slideway oil may hamper the operation of the structures. Accordingly, a thin layer of slideway oil having a relatively low viscosity is applied upon use. The slideway oil is stored in the storage unit  33 . 
         [0056]    The storage unit  33  is provided at an upper side of the frictional part  32  and supplies the slideway oil to the supporting rod  15  oriented to the frictional part  32 . The slideway oil abuts the supporting rod  15  to create a viscous frictional force. The storage unit  33  is larger in inner diameter than the frictional part  32 . The base  37  does not contact the supporting rod  15 . The slideway oil stored in the storage unit  33  seeps into a space between the frictional part  32  and the supporting rod  15 . 
         [0057]    The air cap  31  forms an air vent  40  through which the air accommodated between the air cap  31  and the base  37  is discharged. An air vent is formed in the air cap  31 . The compressed air in the air cap  31  is discharged through the air vent. As the size of the air vent  40  decreases, the amount of compressed air discharged per hour reduces. As the size of the air vent  40  decreases, the damping force increases. The size of the air vent  40  depends on the sealing capacity of the storage unit  33 . As the sealing capacity of the storage unit  33  increases, the air vent  40  is formed to have a small size. As the sealing capacity of the storage unit  33  decreases, the air vent  40  is formed to have a relatively large size. 
         [0058]    The base  37  moves along the supporting rod  15  to compress the air contained in the air cap  31 . The base  37  moves alongside the supporting rod  15 . 
         [0059]    Meanwhile, as shown in the example of  FIG. 4 , a second elastic member  39  may be further provided to expand the base  37  to narrow the gap between the air cap  31  and the base  37 . The second elastic member  39  may be shaped as a ring. The second elastic member  39  elastically pushes the outer periphery of the base  37  outwards, and the base  37  may be thus brought in more tight contact with the air cap  31 . As the elastic force of the second elastic member  39  increases, the frictional force between the base  37  and the air cap  31  also increases. 
         [0060]    In some implementations, a sealing material (e.g., sealing oil) may be accommodated in the storage unit  33 . The sealing oil may, in some implementations, be lubrication (e.g., a slideway oil). However, the sealing material is not limited thereto, and other various types of materials may be used for the sealing material. According to some implementations, a frictional member may be disposed in the storage unit  33 . The frictional member suppresses the supporting rod  15  from moving. The frictional member may be felt. In particular, felt soaked in the slideway oil may provide an effective sealing between the air cap  31  and the supporting rod  15 . 
         [0061]      FIG. 5A  shows a state where the outer tub  2  does not vibrate,  FIG. 5B  shows a state where the outer tub  2  maximally vibrates, and  FIG. 5C  shows a position at which a slideway oil is applied to ensure a damping force under the state shown in  FIG. 5B . 
         [0062]    Referring to  FIGS. 1 to 5C , if the position where the base  37  is maximally inserted in the air cap  31  by the vibration of the outer tub  2  is defined as a peak position, when the base  37  reaches the peak position, the air in the air cap  31  is maximally compressed. In particular, the peak position may vary depending on the load exerted to the suspension  30 . For example, when the outer tub  2  vibrates with the maximum load under the circumstance where the other conditions than varying load of the outer tub  2  remains the same, the outer tub  2  may descend up to the lowermost side of the supporting rod  15 . When the outer tub  2  maximally vibrates under such particular load condition, a partial section of the supporting rod  15  abutting the frictional part  32  is hereinafter defined as a peak friction part M. In particular, the peak frictional part M is positioned at an inner side of the cylindrical part  34  without contacting the frictional part  32  under a no-load state (i.e., when the laundry is not put in the inner tub  3  and no water is fed in the outer tub  2 ) (refer to  FIG. 5A ), and at least a portion thereof is brought in frictional contact with the frictional part  32  when the outer tub  2  vibrates under the maximum load state. 
         [0063]    In some implementations, the peak frictional part M comes in contact with the frictional part  32  (refer to  FIG. 5B ) before the first elastic member  35  is fully compressed, and at least a portion thereof is exposed to an upper side of the air cap  31  when the first elastic member  35  is fully compressed. 
         [0064]    In some implementations, the first elastic member  35  may be exposed to the upper side of air cap  31  while the outer tub  2  vibrates. However, the length of the bottle-neck part of the air cap  31  and/or elastic modulus of the first elastic member  35  are designed so that a frictional force is exerted between the supporting rod  15  and the frictional part  32  even when the outer tub  2  maximally vibrates (when the base  37  reaches the peak position), and in such case, an external force may be thus exerted to allow the air cap  31  and the base  37  to be displaced with respect to each other in order to force the peak frictional part M to be exposed to the upper side of the air cap  31 . Such forced exposure of the peak frictional part M to the upper side of the air cap  31  by an external force corresponds to when applying the slideway oil contained in the storage unit  33  to the peak frictional part M, and the exposure is executed upon manufacture of the product or for maintenance of the product in use. 
         [0065]    The peak position may vary depending on the elastic force exerted from the first elastic member  35 . For example, since the amplitude of the base  37  reduces as the elastic force of the first elastic member  35  increases, the base  37  may be located at a lower position in the air cap  31 . In contrast, as the elastic force of the first elastic member  35  reduces, the amplitude of the base  37  increases, thus allowing the base  37  to be positioned at an upper side in the air cap  31 . 
         [0066]    The lubrication (e.g., the slideway oil) may be applied to the supporting rod  15 . In some implementations, the slideway oil is applied to an overall portion of the supporting rod  15  that is brought in contact with the frictional part  32  by the vibration of the outer tub  2 . 
         [0067]    As shown in the example of  FIG. 5 , the supporting rod  15  may be divided into a first frictional portion K which contacts the frictional part  32  when the outer tub  2  does not vibrate; a second frictional portion P which is brought in contact with the frictional part  32  of the air cap  31  when the outer tub  2  vibrates; and a third portion T corresponding to a lower side of the second frictional portion P. In particular, the third portion T is hereinafter referred to as a frictionless portion T that does not come in contact with the frictional part  32  of the air cap  31  when the outer tub  2  normally vibrates. The length of the frictionless portion T may be determined depending on the first elastic member  35  when fully compressed, the capacity of the outer tub  2 , and threshold amplitude of the overall vibrational system. When the supporting rod  15  is divided so, the slideway oil is applied to at least the first frictional portion K and the second frictional portion P. 
         [0068]    The second frictional portion P includes a peak frictional part M that is brought in contact with the frictional part  32  of the air cap  31  when the amplitude of movement of the supporting rod  15  reaches the peak amplitude due to the vibration of the outer tub  2 . The suspension  30  is structured so that when an external force enough to fully compress the first elastic member  35  is applied, the peak frictional part M is exposed via the frictional part  32  of the air cap  31  to the outside (e.g., in  FIG. 5C ). The suspension  30  includes the storage unit  33  that is formed at an upper side of the frictional part  32  of the air cap  31  and that forms a space for storing the slideway oil between the frictional part  32  of the air cap  31  and the supporting rod  15 . In the scenario of  FIG. 5C , the suspension  30  is formed so that the peak frictional part M is pushed to the outside of the storage unit  33  to be externally exposed. The slideway oil, which is stored in the storage unit  33  and supplies the slideway oil to the supporting rod  15  moving to-and-fro, is thus applied to the peak frictional part M, but may be applied to the frictionless portion T. As described above, this corresponds to a scenario of applying the slideway oil contained in the storage unit  33  to the peak frictional part M, and may be executed, for example, upon manufacture of the product or for maintenance of the product in use. 
         [0069]    The second frictional portion P includes the peak frictional part M and a normal frictional part N. The normal frictional part N is a section of the second frictional portion P except the peak frictional part M. If the outer tub  2  vibrates, the frictional part  32  is primarily brought in contact with the normal frictional part N, and as the vibration increases, the frictional part  32  starts to cause friction with a portion of the peak frictional part M. If the vibration of the outer tub  2  reaches the peak, the frictional part  32  causes friction on the entire peak frictional part M. In the washing machine according to some implementations, thus, the slideway oil is applied to the peak frictional part M to secure a stable damping force. 
         [0070]    The slideway oil is stored in the storage unit  33 . According to some implementations, the peak frictional part M may rise as high as the storage unit  33 , thus applying the slideway oil to the peak frictional part M. According to some implementations, the peak frictional part M may ascend beyond an upper side of the storage unit  33  to be externally exposed. The first elastic member  35  included in the suspension  30  may restrict the height up to which the supporting rod  15  may ascend. 
         [0071]    The second frictional portion P includes a normal frictional part N which corresponds to the rest except the peak frictional part M on which the slideway oil is applied from the storage unit  33 . If the peak frictional part M descends, a majority of the slideway oil applied to the peak frictional part M is rendered to remain in the storage unit  33 . The remaining slideway oil in the storage unit  33  is brought in contact with the normal frictional part N, and thus, the slideway oil is applied on the normal frictional part N. 
         [0072]    The position of the peak frictional part M and the position of the normal frictional part N may vary depending on the elastic modulus of the first elastic member  35  and the second elastic member  39 , the size of the air vent  40 , the viscosity coefficient of the slideway oil, and degree of vibration of the outer tub  2 . Accordingly, proper positions may be derived by one of ordinary skill in the art based on the configuration of the washing machine. 
         [0073]      FIG. 6  illustrates a method of manufacturing a washing machine according to some implementations. 
         [0074]    Referring to  FIG. 6 , a method of manufacturing a washing machine including a casing  1  forming its outer appearance; an outer tub  2  provided in the casing  1  to contain washing water; a supporting rod  15  coupled with the casing  1 ; and a suspension  30  coupled with the outer tub  2 , wherein the supporting rod  15  is inserted into the suspension  30 , and the suspension  30  moves to-and-fro along the supporting rod  15  as the outer tub  2  vibrates to mitigate the vibration of the outer tub  2 , and wherein the suspension includes a frictional part contacting the supporting rod is shown. According to some implementations, the method includes the steps of (S 1 ) inserting the supporting rod  15  in the frictional part  32 ; (S 2 ) exposing, to an outside of the suspension  30 , a first frictional portion K which contacts the frictional part  32  when the outer tub  2  does not vibrate and a second frictional portion P which contacts the frictional part  32  when the outer tub  2  vibrates; and (S 5 ) applying a slideway oil to the supporting rod  15  exposed to the outside of the suspension  30 . 
         [0075]    For assembly, the supporting rod  15  is inserted into the frictional part  32  formed in the suspension  30 . A first frictional member may be disposed before or after the supporting rod  15  is inserted. A base  37  is mounted at an end of the supporting rod  15 . Under such state, the first frictional portion K, the second frictional portion P, and a frictionless portion T remain inserted in the suspension  30 . 
         [0076]    For application of the slideway oil, a force is exerted to the base  37  or the supporting rod  15  in a direction along which the first elastic member  35  is compressed. The force is exerted to the supporting rod  15  or the base  37  substantially until the peak frictional part M is externally exposed (S 3 ). If the peak frictional part M is exposed, the slideway oil is applied to the peak frictional part M (S 5 ). If the application of slideway oil is complete, the base  37  is restored to the original state (S 7 ). 
         [0077]    In order to keep the damping force stable, the slideway oil may be applied to a portion where the suspension  30  and the supporting rod  15  contact each other at a peak position D. The slideway oil may be applied to a portion of the supporting rod  15 , which contacts the frictional part  32  when the base  37  is placed at the peak position D, (the portion is hereinafter referred to as the peak frictional part M). Accordingly, upon application of the slideway oil, the peak frictional part M may be positioned at a higher level than the frictional part  32 , at least. In some implementations, the slideway oil may be applied to the peak frictional part M while positioned at the storage unit  33  or at an upper side of the storage unit  33 . 
         [0078]    Although some implementations 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.