Abstract:
The invention is directed to an anti-tilt swivel mechanism attaching a seat to a base. The mechanism adapted to control the tilting movement urged on the swivel mechanism when a user shifts weight on the seat. The anti-tilt swivel mechanism comprises a tilt stop mounted on the swivel mechanism to move with the chair and engage the base plate along a front edge. The anti-tilt seat swivel mechanism adapted to engage the base plate when a tilting force is applied to the chair preventing the force from being transmitted as a bending force on the swivel mechanism at the mounting plates or the pivot rod.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to an anti-tilt swivel mount for chairs and stools for allowing a chair seat to swivel about a chair base. The swivel seat may be mounted on a fixed or movable base. 
       BACKGROUND OF THE INVENTION 
       [0002]    Swivel mounting mechanisms are used to provide a swiveling seat attached to a chair base to help a person enter and exit a seat. A swiveling seat may also used to accommodate the user pivoting about a chair base to perform several tasks without adjusting the base of the chair. The seat is connected to the base by a generally vertical mounting pin allowing the seat to rotate about the axis of the mounting pin. Prior art swivel seats may be connected to a base by a mechanism having a plate on the chair, a base plate on the base and a pivot pin fixed to one plate and rotationally connected to the other plate. If the user shifts his weight or leans to one side, a bending load on the pivot pin may bend or break the pin causing failure of the chair. 
         [0003]    Prior art swivel disclose a swiveling mechanism using outboard bearing support devices or clamps made from material such as steel and Nylon on the outer edges of rotationally connected plates. The outboard bearing supports extended inwardly between or around the rotationally connected plates to hold the plates in spaced relation. The designs depend on the rigidity of the swivel mechanism to support the tilt resistant mechanisms. 
         [0004]    Alternate designs use a retaining bolt extending between the two swiveling plates to limit deflection of the plates. One of the plates may be connected to a base plate with the other connected to a seat. The slots are used to limit angular rotation about the axis. The fastener on the retaining pin spaced a predetermined distance from a head on the retaining pin to limit tilting about the axis point by limiting the spreading of the plates. The short moment arm between the retaining pin and the pivot pin may cause failure under the weight of a large user. 
         [0005]    Each of these tilt resisting designs in the prior art is integrally manufactured with the swivel base and depends on the strength of the entire swivel mechanism to limit tilting increasing the cost and complicating the design. In addition, the swiveling seat manufacturer is limited to tilt resistant swivel mechanism designs. Therefore, it is desirable to provide an anti-tilt seat swivel design adaptable to existing, mass-produced and readily available swivel mechanisms. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    One embodiment of the present invention may be directed to a swivel mechanism for use with a mounted chair seat on a base such as a legged chair bottom or seat support on a table. The swivel mechanism assembly comprises a base plate mounted on a fixed support such as a chair base, a top swivel plate mounted on the bottom of the seat, a pivot rod or bolt may be pivotally mounted in the base plate and top swivel plate. The pivot rod having a support end extending through the base plate, a seat end extending through the top swivel plate to hold the top swivel plate and bottom swivel plate axially aligned with a bearing channel circumferentially formed about the pivot rod in one of the top swivel plate or bottom swivel plate , a bearing in the channel bearing against the other of the top swivel plate or chair base to hold the top swivel plate and top swivel plate in generally parallel, spaced relation and allow the chair base to rotate with respect to the top swivel plate about the pivot rod. 
         [0007]    The invention may include a tilt stop on the front of the top swivel plate having a rigid tilt stop held in spaced relation to the top swivel plate such that the bottom swivel plate may be between the top swivel plate and the chair base stop. The tilt stop may circumferentially move with the top swivel plate as the top swivel plate pivots about the pivot rod. The chair tilt stop moves in a generally vertical direction when the user shifts weight by leaning against the chair back causing a lifting or tilting force to be applied to the front of the top swivel plate. The tilt stop engages the chair base to prevent transfer of the tilting motion of the chair to the pivot pin and hold the top swivel plate and bottom swivel plate together. The tilt stop also prevents the bearing spacing distance from increasing, a bending load imposed on the rod or deformation of the top swivel plate or bottom swivel plate. 
         [0008]    The tilt stop may have a “U” shape with both vertical ends of the tilt stop attached to the chair thing and a crossbar adapted to engage the base. The chair base may be adapted with a shape to accommodate rotation of the chair with respect to the base causing the tilt stopped to move with the chair about the pivot pin. The crossbar held in spaced relation to the chair surrounding a front portion of the base plate. The pivot pin comprising an axis of rotation of the chair and tilt stop. The pivot pin mounted on the bottom swivel plate generally at a center point of the generally round base plate. The tilt stop moving circumferentially around the base plate as the chair rotates. The tilt stop attached to the top swivel plate and disposed to engage the tilt stop in the rotational range of the swivel mechanism. The allowable swivel rotational range of the seat may be limited by cogs on the bottom swivel plate engaging mating stops formed on the chair base or engaging the tilt stop. 
         [0009]    The above description sets forth, rather broadly, the more important features of the present invention so that the detailed description of the preferred embodiment that follows may be better understood and contributions of the present invention to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and will form the subject matter of claims. In this respect, before explaining at least one preferred embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and to the arrangement of the components set forth in the following description or as illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0010]      FIG. 1  is substantially a perspective view of a first embodiment of the invention. 
           [0011]      FIG. 2  is substantially a side elevation view of a second embodiment of the invention. 
           [0012]      FIG. 3  is substantially a section view of the first embodiment taken at approximately  3 - 3  of  FIG. 1 . 
           [0013]      FIG. 4  is substantially an exploded view of the first embodiment. 
           [0014]      FIG. 5  is substantially an alternate bottom plan view of the first embodiment. 
           [0015]      FIG. 6  is substantially a top perspective view of the pinch guard of the second embodiment. 
           [0016]      FIG. 7  is substantially a bottom perspective view of the pinch guard of the second embodiment. 
           [0017]      FIG. 8  is substantially a bottom perspective view of the second embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part of this application. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. 
         [0019]    Referring to  FIG. 1 , an anti-tilt swivel mechanism may be generally referred to by the number  10  may comprise a base  12  pivotally connected by a swivel mechanism  14  to a chair  16 . The base may comprise a base plate  18  on the base  12  pivotally attached to a chair plate  20  on the chair  16 . Chair  16  further comprises a chair bottom  22 , chair back  24 , chair seat  26 , and chair front  28 . Chair seat  26  may be attached to chair back to  24  and spaced from chair front  28 . Base  12  may be a single pedestal or a frame supporting a plurality of base plates  18  as shown. Alternatively, base plate  18  may be mounted on a bench, wall or other support surface. A 
         [0020]    Referring to  FIG. 2 , the chair  16  may pivot about base plate  18  by swivel mechanism  14  between base plate  18  and chair  16 . Base plate  18  has a generally round shape. A U-shaped tilt stop  30  may be mounted to the swivel mechanism  14  to engage either the base plate  18  or a portion of swivel mechanism  14  when a tilting force  94  may be applied to the swivel mechanism  14  in a generally perpendicular direction to the axis of rotation  31 . A pinch guard  19  may be mounted on the swivel mechanism  14  to guard pinch point between swivel stop  112 ,  114  ( FIG. 4 ). 
         [0021]    Referring to  FIG. 3 , the swivel mechanism  14  further comprises a top swivel plate  32 , a bottom swivel plate  34  and a pivot pin  36 . Top mounting plate  32  comprises a top surface  38  attached to the chair plate  20  by attachment means such as threaded fasteners or the like. Top mounting plate  32  further comprises a bottom surface  40 , and outer edge  42 , a bearing track  44  and a pivot pin aperture  46 . Base plate  18  may further comprise a generally round shape having a first radius of  49  and a base front  51 . Bottom mounting plate  34  further comprises a generally round shape having a second radius  77 , a bottom  48  attached to base plate  18 , a front edge  50 , a bottom bearing track  52  and a pivot pin opening  54 . Second radius  77  may be smaller than first radius  49 . A bearing  56  may be disposed in bearing track  52  between the top swivel plate  32  and bottom swivel plate  34  to rotationally support the top swivel plate  32  and bottom swivel plate  34  in spaced relation to each other. A spring  57  may also be connected between top swivel plate  32  and bottom swivel plate  34  to return the chair  16  to a predetermined position having seat front  28  aligned with front edge  50  of the bottom swivel plate  34  and a front portion  41  of the outer edge  42  of the top swivel plate  32 . Base front  51  may be generally aligned with seat front  28 , bottom swivel plate front edge  50  and top swivel plate front portion  41  and adjacent to tilt stop  30  when bottom swivel plate  34  may be concentrically mounted on base plate  18 . 
         [0022]    Continuing to refer to  FIG. 3 , the pivot pin  36  comprises a head  60 , a shaft  62  and a fastener  64 . The shaft  62  has a first end on the head  60 . The shaft  62  extends through the top pin opening  46  and bottom pivot pin opening  54 . Head  62  bears against bottom plate  34  and fastener  64  may be attached to shaft  62  against top swivel plate to hold the mounting plates  32 ,  34  between the fastener  64  and head  62 . Head  62  bears against bottom swivel plate  34  to hold top swivel plate  32  and bottom swivel plate  34  together. Pivot pin shaft  62  may rotate in pivot pin opening  54  or pivot pin aperture  46  to allow pivotal rotation about axis of rotation  31 . 
         [0023]    Continuing to refer to  FIG. 3 , the tilt resistant bracket  30  comprises an inverted U-shaped bracket having a first leg  70  and a base plate catch  72 . The first leg  70  comprises a first top end  74  and a first bottom end  76 . First bottom end  76  extending in a generally downward direction and generally parallel to the axis of rotation  31  to a position below base plate  18 . Base plate catch  72  may be formed from angle iron having a lip  78 , a shield  80  and a first end  82 . Shield  80  may be a part of the base plate catch or may be a separate part of the anti tilts mechanism  10 . Shield  80  may be extended around anti tilt mechanism  10  to cover swivel stops  112 ,  114 . The first embodiment in  FIG. 3 , illustrates first end  82  may be attached to the first bottom end  76  of the first leg  70 . Lip  78  further comprises an engaging surface  84  and an inner edge  86 . Inner edge  86  of lip  78  may be disposed tangent to a fifth radius  83  from the axis of rotation. Fifth radius  83  being generally smaller than first radius  49 . Engaging surface  84  may be generally parallel to the bottom  90  of base plate  18  and perpendicular to the axis of rotation  31 . Shield  80  may be disposed in a generally parallel orientation to the axis of rotation  31 . A tilting force  94  may be applied to chair  16  by user (not shown) leaning against the chair back  24 . This tilting force  94  may be translated to a bending force against pivot pin  60  which may urge a separation between the bottom swivel plate  34  and front portion  41  of top swivel plate  32 . This bending force  94  may cause the tilt stop  30  to travel in a generally upward direction  97  causing top swivel plate  32  to move upward thereby engaging base plate  18  front portion  51  with base plate catch  72  at pinch point  96  to resist chair tilting. Shield  80  may be disposed adjacent pinch point  96  generally located between top swivel plate  32  and base plate  18  near base plate front edge  51 . 
         [0024]    Referring to  FIG. 4 , the chair  16  may be mounted on chair plate  20  which may be adapted to attach to top mounting bracket  32 . Tilt stop  30  further comprises a second end  98  on base plate catch  72  and a second leg  100 . Second leg  100  may be similar to first leg  70  having a top end  102  adapted to attach to the top swivel plate  32  and a bottom end  104  attached to the second end  98  of the tilt stop  30 . The base  12  may comprise a floor support  106  and a leveling support  108  on base plate  18 . Base plate  18  has a top surface  110  adapted to engage and attach to swivel mechanism  14 . A swivel limiting means may comprise a pair of swivel stops  112 ,  114  may be attached to swivel mechanism  14  to limit the angular rotation of the top swivel plate  32  with respect to bottom swivel plate  34 . 
         [0025]    Referring to  FIG. 5 , swivel mechanism  14  generally comprises the top swivel plate  32 , on chair  16  and the base  12  to hold the chair front  28  adjacent to a table  29 . First leg  70  may be attached to top mounting bracket  32  at a predetermined third radius  75 . Third radius may be generally larger than second radius  77 , having leg mounted outside bottom swivel plate  34 . Shield  80  may be disposed generally perpendicular to a fourth radius  85  from pivot pin  60 . Fourth radius  85  being generally greater than the first radius  49 . Tilt stop  30  may be attached to top mounting bracket  32  having base plate catch  72  adjacent to base plate  18  and adapted to engage base plate  18 . Lip  82  may be disposed below base plate  18  having a lip edge  86  disposed generally perpendicular to a fifth radius  83 . Fifth radius may be generally smaller than second radius. Swivel limiting cogs  120  on bottom swivel plate  34  are adapted to engage swivel stops  112 ,  114  ( FIG. 4 ) on top swivel plate  32  to limit the angle of rotation of chair  16  about the axis of rotation  31 . 
         [0026]    Referring to  FIGS. 6 and 7 , pinch guard  19  comprises a guard mounting plate  120  may have a plurality of holes  122  adapted to align with mounting holes  40 ,  41 . Pinch guard  19  further may comprise guard  124  having side plate  126  and end plate  130 . Each of side plate  126  and end plate  130  may be formed on mounting plate  120  such as formed by bending a single piece of metal at appropriate positions and angles as is known in metal forming. Pinch guard  19  may also be formed of plastic or other resilient material. Side plate  126  and end plate  130  may also have enclosing cover  132  creating a guarded space  134  between mounting plate  120  and cover  132 . Guard mounting plate may have a top surface  136  on chair bottom  22  ( FIG. 2 ) and bottom surface  138  on swivel assembly  14 . 
         [0027]    Referring to  FIG. 8 , anti-tilt swivel mechanism  10  may be mounted between chair  16  and base  12 . Pivot guard  19  may be mounted generally toward the rear of the chair  16  to cover tilt stop  112 ,  114 . Tilt stop  30  may be mounted generally toward the front of chair  16  to engage base plate  18  in the event of a tilting force  94  ( FIG. 2 ) applied to the chair back  24 . 
         [0028]    It should be understood, a user (not shown), sitting in the chair  16  may lean back in the chair  16  and exert a tilting force  94  ( FIG. 2 ) on the chair back mechanism  14  assembly. Tilting force  94  is translated to a bending force on pivot pin  36 . Bending force on pivot pin  36  may cause top swivel plate  32  and bottom swivel plate  34  to be urged away from their generally parallel relationship with top swivel plate  32  on chair  16  and bottom swivel plate  34  on base  12 . This urging of a change of relative position between top swivel plate  32  and bottom swivel plate  34  is urging the front portion of top swivel plate  32  to separate from a front portion of bottom swivel plate  34  which may bend either top swivel plate  32  or bottom swivel plate  34 . The bending force is limited and damage prevented by locking top swivel plate  32  to base plate  18  with tilt stop  30  on top swivel plate  32  engaging bottom swivel plate  34  or base plate  18 . Tilt stop  30  engaging base plate  18  limits the bending force applied to pivot pin  36  preventing bearing  56  from falling out of anti tilt mechanism  10  and damage by bending to top swivel plate  32  and bottom swivel plate  34 . 
         [0029]    Although the description above contains many specifications, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the embodiments of this invention. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents rather than by the examples given. Further, the present invention has been shown and described with reference to the foregoing exemplary embodiments. It is to be understood, however, that other forms, details, and embodiments may be made without departing from the spirit and scope of the invention which is defined in the following claims.