AU2008203386B2

AU2008203386B2 - Suspension apparatus for washing machine

Info

Publication number: AU2008203386B2
Application number: AU2008203386A
Authority: AU
Inventors: Kyung-Mun Jung; Young-Jong Kim; Hyun-Woo Noh
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2007-07-30
Filing date: 2008-07-29
Publication date: 2010-12-02
Anticipated expiration: 2028-07-29
Also published as: KR100879570B1; AU2008203386A1; CN101387061A; US20090031762A1; CN101387061B

Description

Australian Patents Act 1990 - Regulation 3.2 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title Suspension apparatus for washing machine The following statement is a full description of this invention, including the best method of performing it known to me/us: P/00/0 11 5102 C:NRPorblDCCTRN322X914I DOC- /10/2011 RELATED APPLICATION 5 The present invention relates to subject matter contained in priority Korean Application No. 10-2007-0076581, filed on July 30, 2007, the disclosure of which is herein expressly incorporated by reference in its entirety. FIELD The present invention relates to a suspension apparatus for a washing 10 machine, e.g., capable of effectively reducing excessive vibration by maintaining a viscous damping force even when a washing machine is used for a long time. BACKGROUND Generally, a washing machine serves to wash laundry by using a softening process by detergent, a frictional process by water stream occurring as washing 15 blades rotate, an impact process by washing blades, etc. By using a motor as a main driving force, the washing machine performs a washing process, a rinsing process, and a dehydrating process so as to wash laundry with using detergent and water. The washing machine comprises a motor serving as a driving unit, a mechanical part for transmitting energy to laundry, a controller for controlling 20 washing processes, a water supply unit for supplying water, and a water drain unit for discharging water. la The washing machine is largely divided into a cylinder type, an agitator type, and a pulsator type according to washing methods. According to the agitator type, an agitator protruding from the center of an inner tub with a wing shape is rotated in right and left directions thus to wash 5 laundry. According to the pulsator type, laundry is washed by using turbulent stream occurring as a disc-shaped pulsator is rotated. According to the cylinder type, water, detergent, and laundry are put into a drum having a plurality of protrusions, and then are rotated with a low speed in a horizontal axis, thereby washing laundry by an impact occurring as the laundry is lifted and dropped by the 10 protrusions. FIG. 1 is a schematic sectional view of a washing machine in accordance with the related art, and FIG. 2 is a sectional view taken along line 'l-Il'of FIG. 1. Referring to FIGS. 1 and 2, a washing machine 1 comprises a body or a casing 10 that forms appearance; an outer tub 12 mounted in the casing 10; an 15 inner tub 13 mounted in the outer tub 12; a suspension apparatus 20 or suspensions each having one end connected to an upper inner circumferential surface of the body or the casing 10, having another end connected to a lower outer circumferential surface of the outer tub 12, and configured to support the outer tub 12; and a driving unit 15 disposed below the outer tub 12, and configured 20 to drive the inner tub 13. Each of the suspensions 20 comprises a damper cap 22 installed below the outer tub 12; a connection rod 21 having one end penetrating the damper cap 22, and another end mounted to the casing 10; a damper spring 23 mounted in the damper cap 22, and configured to absorb vibration from the outer tub 12; and a 25 damper base 24 installed at a lower opening of the damper cap 22, and configured to support the connection rod 21 or the damper spring 23. A narrow air gap 26 is formed between the damper cap 22 and the damper base 24, and extension springs 25 are installed below the damper base 24. 5 The extension springs 25 serve to extend a lower portion of the damper base 24. Referring to FIG. 3 showing a bottom surface of the suspension apparatus of FIG. 2, each of the extension springs 25 has both ends separated from each other, i.e., a non-consecutive circumference. Here, said both ends separated from 10 each other are curved. Since a non-consecutive part 25a does not come in contact with the damper base 24, the extension spring 25 does not consecutively contact a lower portion of the damper base 24. The suspensions 20 serve to reduce a very large vibration or amplitude occurring by a resonance at the time of excessive vibration (i.e., at the time of 15 starting a dehydration process). According to a basic vibration reducing mechanism, vibration occurring from the inner tub 13 is reduced by a viscous damping force occurring as air is discharged through an air hole (not shown) of the damper cap 22, and by a frictional damping force occurring as the damper cap 22 and the damper base 24 20 come into friction with each other. Here, excessive vibration or amplitude is reduced by a viscous damping force. However, the conventional mechanism has the following problems. An air gap 26 which allows a reciprocation of the washing machine is formed between the damper cap 22 and the damper base 24. If the washing 25 machine 1 is used by approximately 1000 cycles, a clearance of the air gap 26 CANRPonbhDCC\TRN3228914_ 1.DOC-/10/2010 increases to allow a large amount of air to leak through the air gap 26. This causes a viscous damping force to be greatly lowered, thereby not reducing excessive vibration. Besides, since the driving unit 12 is eccentrically installed from the center 5 (C) below the outer tub 2, an initial static deflection of the outer tub 2 is toward the driving unit 12. Furthermore, when the extension springs 25 are used to prevent the air gap 26 from having an increased clearance, a large amount of air is leaked through non-consecutive parts of the extension springs 25. That is, the damper base 24 is 10 not outwardly pushed at the non-consecutive parts 25a of the extension springs 25, but has a flat part 24a. The flat part 24a has a larger clearance than any other parts, which causes a large amount of air to be leaked and thus a viscous damping force to be lowered. Furthermore, when a lubricant such as grease is deposited onto the surface 15 of the damper cap 22 so as to prevent friction or interference between the damper cap 22 and the outer tub 12, the lubricant blocks an air hole (not shown) of the damper cap 22. This causes a viscous damping process not to be smoothly performed. It is desired to address or ameliorate one or more disadvantages or 20 limitations associated with the prior art, or to at least provide a useful alternative. SUMMARY In accordance with the present invention there is provided a suspension apparatus for a washing machine, comprising: 25 a connection rod having one end mounted to a body of a washing machine: a damper cap having another end of the connection rod penetratingly installed thereat, and mounted to an outer tub; an elastic means installed in the damper cap; a damper base mounted to the damper cap, and configured to support the 4 C NRPonbl\DCTM322X9I4 I.DOC-8/10/2110 connection rod or the elastic means; and an extension spring disposed below the damper base, and configured to outwardly extend an edge of the damper base, wherein an interval between the damper cap and the damper base is 5 constantly maintained in a circumferential direction by the extension spring. The described suspension apparatus for a washing machine is capable of constantly maintaining an air gap between a damper base and a damper cap by pushing the damper base in a circumferential direction with a constant force, and capable of reducing lowering of a viscous damping force due to increase of non 10 uniform clearance of the air gap, 4a C:\NRPonbl\DCC\TRM322M914 1.DOC-F/02W10 in which extension springs having a consecutive shape are mounted below the damper base. The described suspension apparatus for a washing machine is capable of preventing a large amount of air leakage due to increase of an air gap between a 5 damper cap and a damper base by mounting a base cap to a lower opening of the damper cap. The described suspension apparatus for a washing machine is capable of preventing lowering of a viscous damping force occurring as an air hole is blocked by a lubricant, by forming an air hole at a base cap rather than at a damper cap. 10 The described suspension apparatus for a washing machine is capable of maintaining an elastic restoration force of an extension spring for a long time by overlapping some parts of the extension spring in a longitudinal direction, and capable of easily mounting the extension spring to a damper base. The described suspension apparatus for a washing machine is capable of 15 constantly maintaining abrasion of a damper base in a circumferential direction by applying an extension spring consecutively contacting the damper base in a circumferential direction, and thus capable of enhancing reliability. The described suspension apparatus for a washing machine, comprises: a connection rod having one end mounted to a body of a washing machine; a 20 damper cap having another end of the connection rod penetratingly installed 5 thereat, and mounted to an outer tub; a damper spring installed in the damper cap; a damper base mounted to one end of the damper cap, sliding along an inner circumferential surface of the damper cap, and configured to support the connection rod or the damper spring,; and extension springs disposed below the 5 damper base, and configured to extend an edge of the damper base to an inner surface of the damper cap, wherein the extension springs have a consecutive circumference. According to another aspect, the suspension apparatus for a washing machine comprises: a connection rod having one end mounted to a body of a io washing machine; a damper cap having another end of the connection rod penetratingly installed thereat, and mounted to an outer tub; an elastic means installed in the damper cap; a damper base mounted to one end of the damper cap, and configured to support the connection rod or the elastic means; and extension springs disposed below the damper base, and configured to outwardly 15 extend an edge of the damper base, wherein an interval between the damper cap and the damper base is constantly maintained in a circumferential direction by the extension springs. Under the above configuration, abrasion of the damper cap and the damper base in a circumferential direction can be constantly maintained, lowering 20 of a viscous damping force due to increase of non-uniform air gap can be reduced, and durability can be enhanced. Here, the extension spring is configured so that some parts thereof can overlap each other in a longitudinal direction. This causes the extension spring to have a consecutive circumference, and allows all parts of the damper base to be 25 outwardly extended. 6 The extension spring is mounted to a concaved groove formed at a lower side of the damper base. The concaved groove formed at a lower inner surface of the damper base serves to stably mount the extension spring thereto, and to prevent the extension spring from being separated from the damper base while 5 the suspension apparatus is operated. Here, rather than the concaved groove, a stopper for preventing the extension spring from being separated from the damper base may be formed at a lower portion of the damper base. Here, a slit for facilitating extension of a lower portion of the damper base 10 may be formed at a lower portion of the damper base. By forming the slit, a lower portion of the damper base can be easily extended even if an extension spring having a small elastic restoration force is used. Both ends of the extension spring are curved toward the center. In order to enhance convenience for installation, the extension spring is firstly made to have a 15 reduced size with the curved portions being pressed, and then is mounted to the damper base. An air hole for air damping may be formed at the damper cap. The air hole may be formed to be disposed at a high position so that the air hole can be prevented from being blocked by a lubricant such as grease. 20 The suspension apparatus for a washing machine may further comprise a base cap mounted to a lower side of the damper cap, and configured to reduce a leakage amount of air inside the damper cap. By mounting the base cap to a lower opening of the damper cap, air leakage through an air gap between the damper cap and the base cap can be completely prevented. It is preferable to maintain a 25 viscous damping force by forming an air hole at the damper cap. 7 Preferably, the base cap and the damper cap are coupled to each other by a hook, but are not limited thereto. The base cap and the damper cap may be coupled to each other by forming a screw thread at a coupling portion therebetween. 5 An air hole for air damping may be formed at the base cap. If air leakage through an air gap is prevented by mounting the base cap to the damper cap, a viscous damping process is not smoothly performed, which may cause excessive vibration. In order to prevent the excessive vibration occurrence, an air hole may be formed at the base cap. Alternately, an air hole io may be formed at the base cap rather than at the damper cap, thereby preventing blocking of the air hole due to a lubricant such as grease. According to still another aspect, the suspension apparatus for a washing machine comprises: a connection rod having a predetermined length; a damper cap to penetratingly insert a part of the connection rod at the center thereof; a 15 damper base mounted to one end of the damper cap, and configured to support the connection rod; and extension springs disposed below the damper base, and configured to constantly maintain an air gap between the damper cap and the damper base, and thus to increase a viscous damping force by air leaked through the air gap. 20 Here, the extension springs consecutively contact lower side surfaces of the damper base. Accordingly, even if a lower portion of the damper base comes into friction with the damper cap to be abraded, an abrasion degree of the lower portion is lower than that of any other portions. A base cap for preventing leakage of air inside the damper cap is mounted 25 below the damper cap. An air hole for a viscosity damping is formed at either the 8 C \NRPonblWDCC\TRN\322X914 1 DOCA/Il/2010 damper cap or the base cap, or at both of them. Under the above configuration, lowering of a viscous damping force due to air inside the damper cap is prevented. The extension spring having a consecutive circumference is mounted to the 5 damper base, thereby uniformly maintaining a clearance of an air gap between the damper base and the damper cap, and preventing lowering of a viscous damping force due to excessive abrasion of a specific part. Increase of a clearance of an air gap due to abrasion of the damper base slidable with respect to the damper cap is prevented, thereby prolonging the life 10 span of the suspension apparatus for a washing machine. An additional base cap is mounted to an opening of the damper cap, thereby preventing lowering of a viscous damping force even if an air gap between the damper cap and the damper base is increased. The described suspension apparatus for a washing machine is capable of 15 preventing lowering of a viscous damping force by forming an additional air hole at a base cap mounted to a lower side of a damper cap, in which the air hole of the base cap is prevented from being blocked by a lubricant deposited to the damper cap. The described suspension apparatus for a washing machine is capable of 20 enhancing productivity by forming an extension spring so that some parts thereof can overlap each other in a circumferential direction or a longitudinal direction, or by forming curved portion at the extension spring, and capable of maintaining an elastic restoration force of the extension spring for a long time. The described suspension apparatus for a washing machine is capable of 25 reducing a large amplitude or noise due to excessive vibration at the time of a dehydration process even when a washing machine is used for a long time. 9 C:\NRPort\DCC\TRN\3228914-1.DOC./I0/2WNW BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the present invention are hereinafter further described, by way of non-limiting example only, with reference to the accompanying drawings, in which: 5 FIG. 1 is a schematic sectional view of a washing machine in accordance with the related art; FIG. 2 is a schematic sectional view of a part of a suspension apparatus for a washing machine in accordance with the related art; FIG. 3 is a bottom view of the suspension apparatus for a washing machine 10 of FIG. 2; FIG. 4 is a schematic sectional view of a suspension apparatus for a washing machine according to one embodiment of the present invention; FIG. 5 is a perspective view of a damper base of the suspension 10 apparatus for a washing machine of FIG. 4; FIGS. 6A to 6C are views respectively showing an extension spring of the suspension apparatus for a washing machine of FIG. 4; FIGS. 7A to 7C are views respectively showing an extension spring of a 5 suspension apparatus for a washing machine according to another embodiment of the present invention; FIG. 8 is a sectional view showing a modification example of the suspension apparatus for a washing machine of FIG. 4; FIG. 9 is an experimental graph comparing a damping force of the 10 conventional suspension apparatus for a washing machine with a damping force of the suspension apparatus for a washing machine of FIG. 4 according to the present invention; and FIGS. 10 and 11 are experimental graphs respectively comparing excessive horizontal and vertical vibration of the outer tub of the conventional 15 washing machine to which the suspension apparatus 20 is applied, with that of the washing machine of the present invention to which the suspension apparatus 200 of FIG. 4 is applied. DETAILED DESCRIPTION OF THE INVENTION 20 Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Hereinafter, the configuration and operation of a washing machine according to one embodiment of the present invention will be explained in more detail with reference to the attached drawings. 25 Explanation for well-known configurations or functions will be omitted. And 11 the same reference numerals will be given to the same parts as those of the aforementioned configurations, and their detailed explanation will be omitted. FIG. 4 is a schematic sectional view of a suspension apparatus for a washing machine according to one embodiment of the present invention, and FIG. 5 5 is a perspective view of a damper base of the suspension apparatus for a washing machine of FIG. 4. A washing machine according to the present invention has the same configuration as the conventional washing machine 1 except a suspension apparatus 200. Therefore, explanation about the same configuration except the 10 suspension 200 of the present invention will be omitted. As shown in FIGS. 4 and 5, the suspension apparatus 200 for a washing machine according to one embodiment of the present invention comprises: a connection rod 210; a damper cap 220 having one end of the connection rod 210 penetratingly formed thereat; a damper spring 230 installed in the damper cap is 220; a damper base configured to support one end of the connection rod 210 penetratingly installed at the damper cap 220; extension springs 260 mounted to a lower side of the damper base 240; and a base cap 250 mounted to a lower side of the damper cap 220. An upper portion of the damper cap 220 is upwardly extending like a neck 20 of a bottle, and the upwardly extending portion encompasses the connection rod 210. The connection rod 210 is positioned inside the damper cap 220 via a through hole 222 formed at the upper portion of the damper cap 220. One end of the through hole 222 is protruding to inside of the damper cap 220, thereby 25 constituting a connection rod supporting portion 223 that encompasses and 12 supports the connection rod 210. One end of the connection rod 210 is fixed to a connection rod fixing portion 245 of the damper base 240. Preferably, the connection rod fixing portion 245 is protruding from an upper side of the damper base 240, and has a 5 predetermined height so as to stably support the connection rod 210. A plurality of protrusions 246 are formed on an outer circumferential surface of the connection rod fixing portion 245. The plurality of protrusions 246 are forcibly inserted into an inner circumferential surface of the damper spring 230, thereby stably supporting the damper spring 230. 10 A lower end of the damper spring 230 is supported by the protrusions 246 on the surface of the connection rod fixing portion 245, and an upper end of the damper spring 230 is supported by a spring supporting portion 224 formed on an inner surface of the damper cap 220. At an initial state, i.e., at a state that the washing machine is not provided 15 with washing water or laundry therein, the damper spring 230 preferably maintains a compressed state, and the damper base 240 for supporting the damper spring 230 is positioned at an inner side of a lower end of the damper cap 220. The reason is as follows. Once laundry or washing water is introduced into the inner tub 13 (refer to FIG. 1), the damper spring 230 is extended due to a weight of the 20 laundry or washing water, and the damper base 240 moves to a lower side of the damper cap 220. Here, if the damper base 240 is positioned at the end of the damper cap 220, laundry, etc. is introduced into the inner tub 13, and the damper base 240 may be completely separated from the damper cap 220. Here, the damper spring 230 is preferably a compression coil spring, but is 25 not limited thereto. As the damper spring 230, any elastic means having an elastic 13 restoration force and configured to absorb or attenuate vibration can be used. For example, a rubber member may be used to connect one end of the connection rod 210 and the connection rod fixing portion 245 of the damper base 240. Also, a rubber pillar (not shown) having a cavity therein may be used as the damper 5 spring 230. When the damper spring 230 is used as an elastic means, one end of the connection rod 210 disposed in the damper cap 220 is preferably disposed inside the damper spring 230. An air hole 221 is formed at an upper portion of the damper cap 220, through which a viscous damping process due to air inside the damper cap 220 is 1o performed. Between an inner surface of the damper cap 220 and an outermost circumference of the damper base 240, a minute air gap 223 is formed. A frictional damping process occurs through the air gap 223. The base cap 250 may be mounted to a lower opening of the damper cap 220. The base cap 250 is coupled to the damper cap 220 by a hook (not shown) 15 formed at the damper cap 220 with receiving the damper base 240 therein. In order to ensure a sealed state inside the damper cap 220, the damper cap 220 and the base cap 250 may be coupled to each other by forming a screw thread at a coupling portion therebetween. The damper base 240 will be explained in more detail with reference to 20 FIG. 5. The connection rod fixing portion 245 connected to one end of the connection rod 210 is formed above the damper base 240, and the plurality of protrusions 246 are provided on an outer circumferential surface of the connection rod fixing portion 245. A spring supporting portion 247 is integrally formed below 25 the connection rod fixing portion 245. Preferably, the spring supporting portion 247 14 is formed in a wide disc shape so as to sufficiently support the damper spring 230. A skirt portion 243 having an area wider than that of the spring supporting portion 247 is integrally formed below-the spring supporting portion 247. Here, the skirt portion 243 is in a thin cylindrical shape having a predetermined height, and 5 an air gap 223 is formed between an outer surface of the skirt portion 243 and an inner surface of the damper cap 220. A plurality of slits 242 are formed at the skirt portion 243 in a height direction, and an extension spring 260 is mounted to an inner surface of the skirt portion 243. Here, in order to prevent the extension spring 260 from being io separated from the skirt portion 243, a concaved groove 244 or stopping jaws 241 are formed on an inner surface of the skirt portion 243. Since the extension spring 260 is mounted to the skirt portion 243 with a diameter decreased than the original diameter, it has an elastic restoration force to restore the original diameter. Due to the elastic restoration force, the edge of the is damper base 240 is extended to an inner surface of the damper cap 220. That is, the skirt portion 243 is pushed to the damper cap 220 thus to be extended. Here, the skirt portion 243 can have a large extension degree by having the plurality of slits 242. The skirt portion 243 can be outwardly extended even by the extension spring 260 having a small elastic restoration force. 20 Either the stopping jaws 241 or the slits 242, or both the stopping jaws 241 and the slits 242 can be formed with consideration of the size of the damper base 240, or an elastic force of the extension spring 260, etc. The extension spring 260 has to be provided with a consecutive circumference. The extension spring 260 will be explained in more detail with 25 reference to FIGS. 6 and 7. 15 FIGS. 6A to 6C are views respectively showing an extension spring of the suspension apparatus for a washing machine of FIG. 4, and FIGS. 7A to 7C are views respectively showing an extension spring of a suspension apparatus for a washing machine according to another embodiment of the present invention. 5 When viewed from the front, the extension spring 260 of the suspension apparatus for a washing machine according to one embodiment of the present invention is in a ring shape having a consecutive circumference (refer to FIG. 6B), whereas when viewed from the side, the extension spring 260 has some parts overlapping each other in a longitudinal direction (refer to FIG. 6C). That is, the io extension spring 260 is wound so that both ends thereof can overlap each other by a predetermined length. Here, curved portions 260a and 260b are formed at both ends of the extension spring 260 toward the center of the extension spring 260. The curved portions 260a and 260b are used to mount the extension spring 260 to the damper 15 base 240. When the curved portions 260a and 260b are pressed at both sides, a diameter of one side of the extension spring 260 is decreased to allow the extension spring 260 to be easily mounted to the damper base 240. Then, when the curved portions 260a and 260b are released, the extension spring 260 is restored to the original state. At the same time, the skirt portion 243 is outwardly 20 extended. As shown in FIG. 6A, the extension spring 260 consecutively contacts lower side surfaces of the damper base 240, i.e., the skirt portion 243, due to its consecutive circumference. That is, all parts of the extension spring 260 come in contact with the skirt portion 243. Accordingly, the air gap 223 between the 25 damper cap 220 and the damper base 240 is uniformly maintained in a 16 circumferential direction of the extension spring 260, thereby preventing non uniform clearance of the air gap 223. As the extension spring 260 having a consecutive circumference is used, the skirt portion 243 of the damper base 240 is prevented from being flatly 5 abraded even when coming into friction with an inner surface of the damper cap 220. Unexplained reference numeral '211' denotes one end of the connection rod 210. FIGS. 7A to 7C are views respectively showing an extension spring of a 10 suspension apparatus for a washing machine according to another embodiment of the present invention. An extension spring 261 of FIG. 7 has the same shape as the extension spring 260 of FIG. 6 except that curved portions are not formed at both ends thereof. 15 When viewed from the front, the extension spring 261 is in a ring shape having a consecutive circumference (refer to FIG. 7B), whereas when viewed from the side, the extension spring 261 has some parts overlapping each other in a longitudinal direction (refer to FIG. 7C). The extension spring 261 can maintain its elastic restoration force for a 20 long time due to its overlapping parts, and can be easily mounted to the skirt portion 243. That is, once the extension spring 261 is held by a user with its central part being pressed, a diameter of one side of the extension spring 261 is decreased to allow the extension spring 261 to be easily mounted to the skirt portion 243. 25 The extension spring 261 of FIG. 7 has the same shape as the extension 17 spring 260 of FIG. 6, except that the curved portions 260a and 260b are formed at both ends of the extension spring 260 of FIG. 6. Accordingly, the extension springs 260 and 261 can be fabricated by using the same molding pattern. More concretely, the extension spring 260 of FIG. 6 can be fabricated by a molding 5 pattern of the extension spring 261 of FIG. 7, and then by forming two curved portions at both ends thereof in a pressing manner, etc. Accordingly, one molding pattern can be used to fabricate two types of extension springs, which enhances the productivity. FIG. 8 is a sectional view showing a modification example of the 10 suspension apparatus for a washing machine of FIG. 4. The suspension apparatus 200' of FIG. 8 is different from the suspension apparatus 200 of FIG. 4 in that an air hole 251 is formed at a base cap 250'. According to the suspension apparatus 200 of FIG. 4, the base cap 250 is mounted to a lower side of the damper cap 220, but an air hole is not formed at 15 the base cap 250. This allows air leakage through the air gap 223 to be prevented, but causes air inside the damper cap 220 to have a difficulty in being discharged out, which can not reduce excessive vibration. In order to solve this problem, the air hole 251 may be formed at the base cap 250'. The air hole 251 of the base cap 250' is formed approximately at a lower 20 surface of the suspension apparatus 200'. Accordingly, even if a lubricant such as grease deposited on the damper cap 220 flows down, the air hole 251 is not blocked. When the air hole 251 is formed at the base cap 250', it is preferable not to form the air hole 221 blocked by a lubricant at the damper cap 220. However, 25 when a sufficient viscous damping force can not be obtained from the air hole 251 18 of the base cap 250', it is effective to form the air hole 221 at the damper cap 220. In this case, in order to prevent the air hole 221 of the damper cap 220 from being blocked by a lubricant such as grease, the air hole 221 is formed at an upper side. In order to reduce excessive vibration of the washing machine by using a 5 viscous damping force occurring from air leakage, either the air hole 221 of the damper cap 220 or the air hole 251 of the base cap 250', or both of them may be formed. This selection has to be performed in the aspect of vibration with consideration of a capacity of the washing machine, a rotation speed of the inner tube at the time of a dehydration process, etc. 10 By using each of the suspension apparatuses 200 and 200', the air gap 223 between the damper cap 220 and each of the dampers bases 250 and 250' can be constantly maintained. This causes a viscous damping force by air leaked through the air gap 223 to be increased. In the present invention, a viscous damping force can be enhanced by two 15 times or more than that of the conventional suspension apparatus 20 (refer to FIG. 1). This allows excessive vibration of the inner tub 13 (refer to FIG. 1) to be enhanced by 30% or more than that of the conventional washing machine. Hereinafter, the function of the suspension apparatus according to one embodiment of the present invention will be compared to that of the conventional 20 suspension apparatus with reference to experimental data. FIG. 9 shows an experimental graph showing an amplitude (mm) according to time (seconds). Referring to FIG. 9, the conventional suspension apparatus 20 shows a damping factor (() of 0.32, whereas the suspension apparatus 200 according to one embodiment of the present invention shows a 25 damping factor (() of 0.74. The damping factor (() denotes a decreasing ratio of a 19 function expressed as coordinates or time, which may be used to represent an indicator to prevent vibration of an object. The larger the damping factor is, the more enhanced a damping function is. Accordingly, it can be inferred that a damping function of the suspension 5 apparatus 200 according to one embodiment of the present invention is enhanced by approximately two times or more than that of the conventional suspension apparatus 20. FIG. 10 is an experimental graph comparing excessive horizontal vibration of the outer tub of the conventional washing machine to which the suspension io apparatus 20 is applied, with that of the washing machine of the present invention to which the suspension apparatus 200 of FIG. 4 is applied. And, FIG. 11 is an experimental graph comparing excessive vertical vibration of the outer tub of the conventional washing machine to which the suspension apparatus 20 is applied, with that of the washing machine of the present invention to which the suspension is apparatus 200 of FIG. 4 is applied. Referring to FIG. 10, the horizontal axis of the graph denotes X-directional vibration and Y-directional vibration of an upper portion of the outer tub 12, and X directional vibration and Y-directional vibration of a lower portion of the outer tub 12, and the vertical axis denotes an amplitude (mm). The graph of FIG. 10 shows 20 that all the amplitudes according to each horizontal vibration of the present invention were decreased by lmm-8.8mm than those of the conventional art. Referring to FIG. 11, the horizontal axis of the graph denotes each Z directional vibration of upper and lower portions of the outer tub 12, and the vertical axis denotes an amplitude (mm). The graph of FIG. 11 shows that all the 25 amplitudes according to each vertical vibration of the present invention were 20 decreased by 2.5mm-2.8mm than those of the conventional art. As aforementioned, when the suspension apparatuses 200 and 200' according to the present invention are used, excessive vibration is reduced by approximately 30% to the maximum state than that of the conventional art, and 5 clearance of the air gap can be uniformly maintained. So far, the present applicant explained about the suspension apparatus applied to a washing machine, but the suspension apparatus may also be applied to various fields such as a washing machine compatible with a drier, a dryer, or a combined washing system. 10 The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teachings can be readily applied to other types of apparatuses. This description is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The 15 features, structures, methods, and other characteristics of the exemplary embodiments described herein may be combined in various ways to obtain additional and/or alternative exemplary embodiments. As the present features may be embodied in several forms without departing from the characteristics thereof, it should also be understood that the 20 above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by 25 the appended claims. 21 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other 5 integer or step or group of integers or steps. The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the io common general knowledge in the field of endeavour to which this specification relates. 15 20 25 22

Claims

1. A suspension apparatus for a washing machine, comprising: a connection rod having one end mounted to a body of a washing 5 machine; a damper cap having another end of the connection rod penetratingly installed thereat, and mounted to an outer tub; an elastic means installed in the damper cap; a damper base mounted to the damper cap, and configured to support the io connection rod or the elastic means; and an extension spring disposed below the damper base, and configured to outwardly extend an edge of the damper base, wherein an interval between the damper cap and the damper base is constantly maintained in a circumferential direction by the extension spring. 15

2. The suspension apparatus for a washing machine of claim 1, wherein the elastic means is a damper spring.

3. The suspension apparatus for a washing machine of claim 1 or 2, 20 wherein the extension spring is configured so that some parts thereof overlap each other.

4. The suspension apparatus for a washing machine of claim 1 or 2, wherein the extension spring is mounted to a concaved groove formed at a lower 25 side of the damper base. 23 C \NRPunbrDCOTRWN\22H914 .DOC-./1f/201

5. The suspension apparatus for a washing machine of claim 1 or 2, wherein either stopping jaws for preventing separation of the extension springs or slits for extending a lower side of the damper base are formed at a lower side of 5 the damper base.

6. The suspension apparatus for a washing machine of claim 1 or 2, wherein the extension spring has both ends curved toward the center. 10

7. The suspension apparatus for a washing machine of claim 1 or 2, wherein an air hole for air damping is formed at the damper cap.

8. The suspension apparatus for a washing machine of claim 1 or 2, further comprising a base cap mounted to a lower side of the damper cap, and 15 configured to reduce an amount of leakage of air inside the damper cap.

9. The suspension apparatus for a washing machine of claim 8, wherein the base cap and the damper cap are coupled to each other by a hook. 20

10. The suspension apparatus for a washing machine of claim 8, wherein an air hole for air damping is formed at the base cap.

11. A suspension apparatus for a washing machine, substantially as hereinbefore described, with reference to Figures 4-11 of the accompanying 25 drawings 24