Abstract:
A self-adjusting furniture foot assembly has an upper member slidably engaged with a lower member. Between the upper and lower members, a biasing member urges the two apart while a dampening member resists acceleration of the second member toward the first member. Consequently, the foot assembly can slowly compensate to an uneven support surface for an item of furniture, and can quickly reset itself when the furniture is lifted.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to apparatus and methods for supporting furniture. More particularly, the present invention relates to apparatus and methods for supporting furniture on uneven surfaces to automatically stabilizes the furniture to prevent it from rocking.  
           [0003]    2. Description of the Related Art  
           [0004]    There are few if any people who have not, at one time or another, sat at a table that was not squarely supported on the ground. When, for example, the ground below a table is uneven, the legs of the table do not all touch the ground at the same time. As a result, the table will rock back and forth. If such a table is in a restaurant, such a rocking motion can result in spilled food or drinks, causing patrons to be annoyed or upset and causing waiters to make unnecessary, repeated trips to and from the table to replace spilled items. Each of these situations can result in a bad experience for the patron, a bad tip for the waiter, or a bad reputation for the establishment.  
           [0005]    A wide variety of articles, such as matchbooks, playing cards, and pieces of wood, have been used to shim the short leg of a table to compensate for an uneven surface. Invariably, such solutions are temporary at best. Similarly, tables have been manufactured with threaded feet to be adjustable for compensating for an uneven surface. The adjustment that is suitable for one position, however, may not be suitable for another, ultimately resulting in the table again rocking. Although many attempts have been made, there is yet to be a widely accepted solution to this age-old problem.  
           [0006]    Similarly, most every type of furniture, such as chairs and benches, also have such a problem when used on uneven surfaces. Thus, there is a need for adjustable furniture feet that not only adjust for uneven surfaces, but that also will readjust as the furniture is moved.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    The present invention is directed toward items of furniture with feet assemblies that automatically adjust to uneven surfaces, toward foot assemblies that can be attached to furniture for such a purpose, and toward a method for adjusting furniture to compensate for uneven surfaces. One embodiment of the present invention incorporates a first foot member, a second foot member, a biasing member and a dampening member. The first foot member is coupled to a lower portion of a piece of furniture, such as the bottom of a leg. The second foot member is slidably coupled to the first foot member to reciprocate with respect to the first foot member along an axis that, during use, intersects the surface supporting the furniture, such as a floor. The biasing member is positioned between the first and second foot members to urge them apart from each other. The dampening member is also coupled between the first and second foot members, and contains a flowable liquid that is forced through a restricted opening when the second foot member moves toward the first foot member. As a result, acceleration of the second foot member toward the first foot member is dampened.  
           [0008]    During use, the biasing member urges the second foot member apart from the first foot member until the furniture is set on the supporting surface. If one of the second foot members does not contact the supporting surface after the furniture is set down, the weight of the furniture will force the adjacent foot members to collapse against the force of the biasing member and the resistance of the dampener, until the elevated foot member contacts the supporting surface. As a result, shortly after the furniture is repositioned on the uneven surface, the furniture will settle until it is stabilized.  
           [0009]    In another embodiment, dampening member of the adjustable foot assembly comprises a cavity having first and second chambers divided by a dividing member with an aperture therein. As the second foot member moves toward the first foot member, fluid in one of the two chambers is forced through the aperture into the other chamber. The size and shape of the aperture can be selected to create a desired rate of movement.  
           [0010]    In still another embodiment of the present invention, one chamber of a dual-chambered cavity is made from a rigid material while the other chamber is made from a resilient material. As the second foot member moves toward the first foot member, the resilient material of the second chamber is deformed, forcing the fluid through the aperture and into the first chamber.  
           [0011]    In still another embodiment of the present invention, a valving means is positioned with the aperture between the first and second chambers. The valving means is movable between an open position in which the fluid is relatively free to flow between the first and second chambers, and a closed position in which the fluid is substantially restricted between the first and second chambers. As the second foot member moves toward the first food member, an increased pressure in the fluid moves the valving means from the open position to the closed position. Further movement of the second foot member toward the first foot member is dampened because the valve is in the closed position. If the furniture were lifted, however, the force urging the second foot member toward the first foot member would be removed, resulting in a pressure decrease in the resilient chamber. When the pressure in the resilient cavity decreased below a pre-determined threshold, the valving means moves from the closed position back to the open position, allowing the foot assembly to return to its default configuration at an increased rate.  
           [0012]    In still further another embodiment, a biasing means is positioned between the wall of the resilient chamber and the valving means. The biasing member increases the force on the valving means, resulting in an increased dampening effect.  
           [0013]    The present invention is also directed toward furniture that is configured with such foot assemblies, and to methods of adjusting furniture to compensate for uneven surfaces.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is an isometric view of a portion of an item of furniture and a self-adjusting foot assembly according to one embodiment of the present invention.  
         [0015]    [0015]FIG. 2 is an exploded view of the foot assembly of FIG. 1.  
         [0016]    [0016]FIG. 3 is a plan view of a lower cup member of the foot assembly of FIG. 2.  
         [0017]    [0017]FIG. 4 is a sectional elevation view of the lower cup member of FIG. 3, viewed along Section  4 - 4 .  
         [0018]    [0018]FIG. 5 is a plan view of a ferrule of the foot assembly of FIG. 2.  
         [0019]    [0019]FIG. 6 is a sectional elevation view of the ferrule of FIG. 5, viewed along Section  5 - 5 .  
         [0020]    [0020]FIG. 7 is a diametric sectional view of a diaphragm member of the foot assembly of FIG. 2.  
         [0021]    [0021]FIG. 8 is a plan view of a button valve of the foot assembly of FIG. 2.  
         [0022]    [0022]FIG. 9 is a sectional elevation view of the button valve of FIG. 8, viewed along Section  9 - 9 .  
         [0023]    [0023]FIG. 10 is a plan view of a washer of the foot assembly of FIG. 2.  
         [0024]    [0024]FIG. 11 is a sectional elevation view of the washer of FIG. 10, viewed along Section  11 - 11 .  
         [0025]    [0025]FIG. 12 is a plan view of an upper cup member from the foot assembly of FIG. 2.  
         [0026]    [0026]FIG. 13 is a sectional elevation view of the upper cup member of FIG. 12, viewed along Section  13 - 13 .  
         [0027]    [0027]FIG. 14 is a sectional elevation view of the foot assembly of FIG. 1 in an extended configuration, as viewed along a diametric section.  
         [0028]    [0028]FIG. 15 is a sectional elevation view of the foot assembly of FIG. 14 in a compressed configuration.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]    The present invention is generally directed toward furniture and foot assemblies for furniture that adjust automatically to uneven surfaces, and for methods of doing the same. Embodiments of the present invention allow an item of furniture to be placed upon uneven surfaces, and automatically stabilize the furniture to prevent it from rocking. Many specific details of certain embodiments of the invention are set forth in the following description and illustrated in FIGS.  1 - 15  to provide a thorough understanding of such embodiments. One skilled in the art, however, will understand that the present invention may have additional embodiments, or may be practiced without several of the details described in the following description.  
         [0030]    [0030]FIG. 1 illustrates a portion of an item of furniture  20  supported by a foot assembly  22  on a supporting surface  24 . The illustrated foot assembly  22  is attached to the item of furniture  20  by a threaded fastener  26  that engages a complementary opening (not shown) in the bottom of the item of furniture. One of ordinary skill in the art will immediately appreciate the various ways in which a foot assembly can be coupled to an item of furniture.  
         [0031]    [0031]FIG. 2 is an exploded view of the foot assembly. The fastener  26  is attached to an upper surface  28  of an upper cup member  30 . The upper cup member  30  is oriented such that an opening  32  of the cup faces downward during use when an upper surface  28  is adjacent the item of furniture  20 . The fastener  26  can be attached to the upper cup member  30  by a wide variety of means, such as spot welding.  
         [0032]    A washer  34  is shaped to complement the opening  32  in the upper cup member  30 , and is sized to be received within the opening. The washer  34  has an aperture  36  therein that extends through the entire thickness of the washer.  
         [0033]    A button valve  38  is configured to engage the aperture  36  from the side of the washer  34  opposite the upper cup member  30 . The illustrated button valve  38  has four prongs  40  thereon that engage the aperture  36  in the washer  34 , and that retain the button value  38  to the washer. As discussed in more detail below, the prongs  40  are long enough to allow the button valve  38  to move axially against and apart from the washer  34 .  
         [0034]    A conical spring  42  is positioned against an under surface  44  of the button valve  38 . An uppermost coil  46  of the conical spring  42  is sized to contact the under surface  44  of the button valve  38 . The uppermost coil  46  can be retained laterally against the button valve  38 , such as by an elevated ridge  82  (FIG. 9) around the perimeter of the under surface  44 .  
         [0035]    A diaphragm  48  is sized to receive the conical spring  42 . An upper shoulder  50  of the diaphragm  48  is sized and shaped to be received by the opening  32  in the upper cup member  30 . Accordingly, the upper shoulder  50  of the diaphragm  48  contacts the washer  34  when the two are configured for use. As illustrated in FIG. 14, the upper cup member  30  can be crimped over the washer  34  and the upper shoulder  50  of the diaphragm  48  to retain the washer, button valve  38 , conical spring  42  and diaphragm in position against the upper cup member. In the illustrated embodiment, the diaphragm  48  is made from a resilient material. As a result, when crimped into the upper cup member  30 , the diaphragm seals the upper cup member and the elements therebetween from the surrounding environment.  
         [0036]    A ferrule  52  has an upper opening  54  that is sized and shaped to closely receive the lower portion of the diaphragm  48  that projects from the upper cup member  30  during use. The upper opening  54  in the ferrule  52  extends axially through the length of the ferrule, and exits through a lower opening  56 . A pair of opposing tabs  58  project outwardly from the wall of the ferrule  52  surrounding the lower opening  56  in a generally radial direction with respect to the circular cross section of the ferrule.  
         [0037]    A cylindrical spring  60  has a central opening  62  extending therethrough. The central opening  62  is sized to fit over the ferrule  52  and contact the upper cup member  30 . When contacting the upper cup member  30  and fully extended, the illustrated cylindrical spring  62  is tall enough to extend from the upper cup member beyond the entire body of the ferrule  52 .  
         [0038]    A lower cup member  64  is generally hollow and has an opening  66  therein that is sized and shaped to receive all of the elements of the foot assembly therein, with the exception of the fastener  26  and, possibly, a portion of the upper cup member  30 . A protuberance  68  projects upward from a bottom portion  70  of the lower cup member  64  into the hollow interior of the lower cup member. The protuberance  68  is sized and shaped to fit into the lower opening  56  and the ferrule  52 .  
         [0039]    [0039]FIGS. 3 and 4 further illustrate some of the details of the lower cup member  64  of this particular embodiment of the present invention. The opening  66  is surrounded by a mouth  72  that curves inward along the perimeter of the opening. As discussed below, the mouth  72  helps to retain the lower cup member  64  to the upper cup member  30 .  
         [0040]    A pair of opposing arms  74  project upward from the bottom portion  70  of the lower cup member  64 . As discussed in more detail below, the arms  74  abut against the tabs  58  on the ferrule  52  during use to allow an individual to screw the foot assembly  22  into a piece of furniture by turning the lower cup member  64 .  
         [0041]    [0041]FIGS. 5 and 6 further illustrate specific details about the ferrule  52  of this particular embodiment of the present invention. The upper opening  54  of the ferrule  52  is surrounded by a lip  76  that is flared outward around the upper opening. An upper portion  78  of the ferrule  52  is tapered inward along a length of the ferrule from a widest portion adjacent with lip  76  to a narrowest portion generally central along the length of the ferrule. As described in more detail below, the lip  76  and upper portion  78  of the ferrule  52  are sized and shaped to receive the diaphragm  48 , and to prevent the diaphragm from bulging outside the boundaries defined thereby during compression.  
         [0042]    The lower opening  56  in the illustrated ferrule  52  is generally cylindrical, and is sized to allow the protuberance  68  in the lower cup member  64  to enter the ferrule  52  through the lower opening. As discussed in more detail below, the protuberance  68  will pass through the lower opening  56  to depress the diaphragm  48 .  
         [0043]    [0043]FIG. 7 further illustrates some of the details of the diaphragm  48  of this particular embodiment of the present invention. The diaphragm  48  is generally semi-spherical to complement the size and shape of the upper portion  78  of the ferrule  52 , and is sufficiently resilient to conform to the same. The upper shoulder  50  of the diaphragm  48  terminates at a skirt  80  that projects downward from the upper shoulder. The skirt  80  is sized and shaped to surround the lip  76  of the ferrule  52 . As discussed in more detail below, the skirt  80  will help seal the internal cavity defined by the upper cup member  30  and the diaphragm  48  from the surrounding environment.  
         [0044]    [0044]FIGS. 8 and 9 further illustrate some of the details of the button valve  38  of this particular embodiment of the present invention. The under surface  44  of the button valve  38  is surrounded by an annular ridge  82  that is sized to receive the uppermost coil  46  of the conical spring  42 . The annular ridge  82  helps to retain the conical spring  42  in its operating alignment.  
         [0045]    Each of the prongs  40  terminates at its distal end in a tapered surface  84  that is shaped to facilitate insertion of the button valve  38  into the aperture  36  of the washer  34 . An enlarged head  86  resists separation of the button valve  38  from the washer  34 . An elongated neck  88  separates the enlarged head  86  from the button valve  38 . The neck  88  has a length that is greater than the thickness of the washer  34  to allow the button valve  38  to move actually with respect to the aperture  36 .  
         [0046]    [0046]FIGS. 10 and 11 further illustrate some of the specific details of the washer  34  of this embodiment of the present invention. A central portion  90  of the illustrated washer  34  adjacent the aperture  36  is offset laterally with respect to an outer portion  92  of the washer. The shape of the washer  34  can serve to position the aperture  36  and, in turn, the button valve  38  closer to the diaphragm  48  and protuberance  68  when the foot assembly  22  is fabricated.  
         [0047]    [0047]FIGS. 12 and 13 further illustrate some of the specific details of the upper cup member  30  of this particular embodiment of the present invention. An annular shelf  94  divides an upper cavity  96  from the opening  32  of the upper cup member  30 . The diameter of the upper cavity  96  is thus smaller than the diameter of the opening  32 . The shelf  94  is sized to prevent the washer  34  from entering the upper cavity  96 . The washer  34  will instead rest along its perimeter against the shelf  94 . A lower edge  98  of the upper cup member  30  is sized to receive not only the washer  34 , but also the upper shoulder  50  and skirt  80  of the diaphragm  48  and the lip  76  of the ferrule  52 .  
         [0048]    [0048]FIG. 14 illustrates the foot assembly  22  after it has been completely assembled. The foot assembly  22  illustrated in FIG. 14 is fully extended, which is the configuration of the foot assembly when the item of furniture  20  is lifted off of the supporting surface  24 . A volume of liquid  100  is retained within the cavity defined by the diaphragm  48  and the upper cup member  30 . The volume of liquid  100  in the illustrated configuration does not fill the upper cavity  96  of the upper cup member  30 . The outer portion  92  of the washer  34 , the upper shoulder  50  of the diaphragm  48 , and the lip  76  of the ferrule  52  are urged against the shelf  94  of the upper cup member  30 . The lower edge  98  of the upper cup member  30  is crimped to retain these elements, and to seal the cavity from the surrounding environment. The skirt  80  of the diaphragm  48  is compressed between the lip  76  of the ferrule  52  and the lower edge  98  of the upper cup member  30 .  
         [0049]    The button valve  38  is engaged with the aperture  36  in the washer  34 , and the conical spring  42  extends from the undersurface  44  of the button valve to the diaphragm  48 . The mouth  72  of the lower cup member  64  is positioned above the shelf  94  of the upper cup member  30  to retain the lower cup member to the upper cup member. The cylindrical spring  60  urges the lower cup member  64  away from the upper cup member  30  until the mouth  72  contacts the shelf  94 .  
         [0050]    In this configuration, the foot assembly  22  can be engaged with an item of furniture  20 , such as by threading the foot assembly into the item of furniture. The tabs  58  extending from the ferrule  52  are positioned to obstruct movement of the arms  74  of the lower cup member  64 . As a result, when the lower cup member  64  is rotated manually by an individual, the arms  74  contact the tabs  58  to cause the entire foot assembly  22  to rotate. The individual can thus screw the foot assembly  22  into the threaded opening in an item of furniture  20 .  
         [0051]    [0051]FIG. 15 illustrates the foot assembly  22  in its compressed configuration. The foot assembly  22  might be moved into the compressed configuration after the item of furniture  20  is set onto an uneven supporting surface  24  and the weight of the item of furniture compresses the foot assembly to compensate for the uneven supporting surface.  
         [0052]    When the item of furniture  20  is set onto a surface  24 , the weight W of the item of furniture pushes downward on the upper cup member  30  and an equal resultant force R urges upward from the supporting surface on the lower cup member  64 . If the weight W is greater than the restoring forces of the conical spring  42  and the cylindrical spring  60 , the upper cup member  30  will move toward the lower cup member  64 . As the cup members compress, the protuberance  68  deforms the diaphragm  48 , forcing the liquid  100  to pass around the button valve  38  and through the aperture  36 . The resistance created by the button valve  38  dampens the movement of the lower cup member  64  with respect to the upper cup member  30 .  
         [0053]    The restoring forces of the conical spring  42  and the cylindrical spring  60  can be selected such that the weight W and resultant force R are slightly greater than the restoring forces when the item of furniture  20  is in contact with the supporting surface  24 . Accordingly, when the item of furniture is supported by a level surface, the foot assembly  22  will ultimately remain in or close to the compressed configuration of FIG. 15, as the weight of the table will slowly compress the foot assembly  22  until the item of furniture  20  touches plastic mouth  72  or until the foot assembly is fully compressed. However, when one or more of the foot assemblies  22  does not contact the supporting surface  24 , there would be no resultant force R. As a result, those foot assemblies  22  not touching the ground would extend they contact the supporting surface  24 . The foot assemblies  22  thereby allow the item of furniture  20  to be set onto an uneven supporting surface  24 , and automatically adjust for the uneven support surface.  
         [0054]    In an alternate embodiment, the restoring forces of the conical spring  42  and the cylindrical spring  60  can be selected such that the weight W and resultant force R are greater than the restoring forces only when one of the feet of the item of furniture  20  is not in contact with the supporting surface  24 . Accordingly, when the item of furniture is supported by a level surface, the foot assembly  22  will remain in or close to the extended configuration of FIG. 14. However, when one of the foot assemblies  22  does not contact the supporting surface  24 , the weight W would then be greater than the restoring forces of some or all of the other foot assemblies  22 , as the weight would be distributed through fewer feet. As a result, those foot assemblies  22  would compress until the foot assembly that is not supported comes into contact with the supporting surface  24 . The foot assemblies  22  thereby allow the item of furniture  20  to be set onto an uneven supporting surface  24 , and automatically adjust for the uneven support surface.  
         [0055]    If the item of furniture  20  is moved, the foot assemblies  22  that are lifted off of the supporting surface  24  will immediately spring back into the extended configuration. The lower cup member  64  is free to move away from the upper cup member  30  without displacing any of the liquid  100 . Consequently, when the foot assembly  22  is lifted off of the supporting surface  24 , the foot assembly immediately moves into the extended configuration. When the lower cup member  64  moves into the extended configuration, the force of the conical spring  42  and the resiliency of the diaphragm  48  move the diaphragm back into its extended configuration illustrated in FIG. 14, drawing the liquid  100  back into its original distribution. Because the prongs  40  allow the button valve  38  to move axially with respect to the washer  34 , as the liquid  100  moves downward, the button valve also moves downward. Downward movement of the button valve  38  increases the size of the flow paths through the aperture  36 , increasing the flow rate of the liquid  100 . Accordingly, the rate at which the foot assembly  22  extends is significantly greater than the rate at which the foot assembly compresses.  
         [0056]    As stated and implied above, the foot assembly of the present invention provides a number of advantages over the prior art. For example, the foot assembly not only allows an item of furniture to be set on an uneven surface, but it also allows the item of furniture to be moved with respect to that uneven surface. For example, a table on an uneven restaurant floor can be repeatedly moved between patrons without the foot assemblies needing adjustment. Likewise, when the item of furniture is moved from an uneven surface to a level surface, the foot assemblies again require no adjustment. Still further, because the liquid in the foot assembly is completely sealed from the surrounding environment, dirt, dust and other objects on the floor do not adversely affect the functioning of the foot assembly.  
         [0057]    From the foregoing it will be appreciated that, although specific embodiments of the invention have been shown and described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.