Abstract:
An improved rivet system is disclosed for use in motion furniture linkage and the like. The improved rivet system incorporates an electrically conductive plastic washer which eliminates the need for oil lubrication while maintaining the ability to electrostatically paint the linkage assembly. The rivet system is such that installation is simplified and manufacturing inconsistencies are reduced.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 10/330,867 filed on Dec. 27, 2002, which is a continuation-in-part of U.S. patent application Ser. No. 10/196,898 filed on Jul. 16, 2002. The disclosures of the above applications are incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to reclining chairs and, more particularly, to rivets that are used as pivot points such as to allow the chair frame to recline and to extend the legrest of a reclining chair.  
           [0003]    Traditionally, reclining chairs are equipped with an actuation mechanism which is operatively interconnected between a prefabricated chair frame and a stationary base assembly. The actuation mechanism is typically a combination of various mechanical linkages operable for providing various comfort features such as independent reclining movement of a seat assembly as well as actuation of an extensible leg rest assembly and associated tilting of the chair frame. Rivet joints are the primary means utilized to fabricate the pivots in these various mechanical linkages. The rivets securely couple the connecting links while allowing a smooth pivoting motion. Some rivet systems utilize an oiled washer to reduce friction within the rivet joint.  
           [0004]    Connecting links that are exposed when the legrest is extended are typically coated to prevent oxidation and provide an aesthetically pleasing surface. Coatings that are not electrostatically applied can flake and adversely affect carpet or other flooring. Extreme amounts of flaking may result in damage and carpet replacement. Electrostatic coating the assembly of the connecting links requires a continuous metal-to-metal contact between the connecting links which may not be provided by some rivet systems.  
           [0005]    While many conventional reclining chairs operate satisfactorily, furniture manufacturers are continually striving to develop improved actuation mechanisms for reducing system complexity and increasing structural soundness and smoothness of operation. Furthermore, there is a continuing desire to develop improved rivet systems which will result in reduced costs while promoting increased efficiency and improved product quality.  
         SUMMARY OF THE INVENTION  
         [0006]    In accordance with the principles of the present invention, an improved rivet system is disclosed which does not require lubricating oil, which is more simple and less costly to assemble and which reduces manufacturing inconsistencies when compared to conventional rivet systems. The improved rivet system is readily adaptable for use with conventional actuation mechanisms.  
           [0007]    In accordance with a preferred embodiment, a wall proximity reclining chair is provided to include the improved rivet system that replaces existing rivets. The rivet system incorporates a plastic bushing to reduce friction within the rivet joint. This rivet system can utilize either a metal wave washer or a plastic spring bushing to reduce the lateral freeplay within the connecting links. A thrust washer between the connecting links of the rivet joint is a plastic and metal composite washer that provides a substantially uniform continuous electrical path between the links. Elimination of the oiled washer will reduce manufacturing time and eliminate the oiling equipment resulting in reduced manufacturing costs. Additional objects, advantages, and features of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a perspective view of a wall proximity reclining/tilt chair in accordance with the present invention;  
         [0009]    [0009]FIG. 2 is a perspective view of the internal frame of the wall proximity reclining/tilt chair shown in FIG. 1;  
         [0010]    [0010]FIG. 3 is an enlarged perspective view of the actuation mechanism shown in FIG. 2;  
         [0011]    [0011]FIG. 4 is an exploded prospective view of a pantograph linkage mechanism shown in FIG. 2 illustrating the improved rivet both partially and fully assembled;  
         [0012]    [0012]FIG. 5 is an enlarged view of the improved rivet system, fully assembled;  
         [0013]    [0013]FIG. 6 is an enlarged view of a conventional rivet system fully assembled;  
         [0014]    [0014]FIG. 7 is a detailed plan view of the shoulder bushing shown in FIG. 5; and  
         [0015]    [0015]FIG. 8 is a detailed side view of the shoulder bushing shown in FIG. 5.  
         [0016]    [0016]FIG. 9 is an exploded prospective view of a pantograph linkage mechanism incorporating an alternate embodiment of the improved rivet system of FIG. 5.  
         [0017]    [0017]FIGS. 10 a  and  10   b  are enlarged views of an alternate embodiment of the improved rivet system of FIG. 5.  
         [0018]    [0018]FIG. 11 is a sectional view of a spring shoulder bushing of the improved rivet system of FIG. 10.  
         [0019]    [0019]FIGS. 12 a  and  12   b  are an alternate embodiment of the thrust washers shown in FIG. 10 b.    
         [0020]    [0020]FIGS. 13 a  and  13   b  are enlarged views of the metal contact shown in FIGS. 12 a  and  12   b.    
         [0021]    [0021]FIG. 14 a  is another alternate embodiment of the thrust washers shown in FIG. 10 b.    
         [0022]    [0022]FIG. 14 b  is a cross-sectional view of the thrust washer of FIG. 14 a  take taken through line  14   b - 14   b.    
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    In accordance with the teachings of the present invention, an improved rivet system for use in single and multi-person articles of furniture (i.e. chairs and sofas or loveseats) is disclosed. A general understanding of the art to which the present invention pertains is disclosed in U.S. Pat. No. 5,570,927n which is commonly owned by the assignee of the present invention and the disclosure of which is expressly incorporated by reference herein. As will be described, the rivet system utilizes a friction reducing bushing that does not require lubricating oil.  
         [0024]    With reference to FIG. 1, the article of furniture shown is a combination wall proximity recliner and tilt chair, hereinafter referred to wall proximity reclining/tilt chair  10 , which includes a pre-assembled actuation mechanism  12 .  
         [0025]    As best seen in FIG. 2, actuation mechanism  12  of wall proximity reclining/tilt chair  10  is integrated into and operably suspended from chair frame  21  and, in particular, from left and right side frame assemblies  24 . In addition to side frame assemblies  24 , chair  10  also includes a front rail assembly  26  and a rear rail  28  which, when interconnected, define a rigid “box-like” chair frame. Preferably, most of the structural frame components including side frame assemblies  24 , front rail assembly  26  and rear rail  28  are each constructed in a manner which enables them to support springs, padding, upholstery, etc. in order to complete a decorative and stylish reclining/tilt chair  10 . More preferably, each of these frame components, except for front rail assembly  26  and rear rail  28 , are fabricated from one or more wood panels and/or rails that are fixedly secured together by suitable fasteners, such as dowels, staples, nails and screws, and which may be reinforced at critical joints by metal reinforcement plates or brackets and/or wood corner blocks in a known manner. As previously noted, each frame component is individually pre-assembled for subsequent modular assembly into wall proximity reclining/tilt chair  10 . However, it is to be understood that the specific construction shown for each frame component is merely exemplary in nature.  
         [0026]    With reference to FIGS. 2 and 3, actuation mechanism  12  is shown to include a drive rod  30  and front support shaft  32 , both of which are spatially oriented to be precisely located and “suspended” from left and right side frame assemblies  24 . In the preferred construction, drive rod  30  is an elongated square shaft having a manually-operable handle (not shown) secured thereto adjacent an upholstered exterior portion of one of side frame assemblies  24  and which can be easily reached by a person seated in chair  10  for convenient actuation thereof. In addition, leg rest assembly  16 , as shown in FIG. 1, is supported for extensible movement on actuation mechanism  12 . More specifically, leg rest assembly  16  includes left and right pantograph linkage mechanisms  34  which is operable associated with drive rod  30  and front support shaft  32  for permitting the seat occupant to selectively actuate leg rest assembly  16  to response to rotation of drive rod  30  via the handle.  
         [0027]    Referring to FIGS. 4 and 5, pantograph linkage mechanisms  34  are assembled with rivet joints  36  and connecting links  37 . These joints utilize an oil-less rivet system  38  which allows the connecting links  37  of pantograph linkage mechanism  34  to pivot about a pivot axis. These relative rotations of the connecting links  37  are constrained by the dynamics of the multi-bar linkage design. Rivet system  38  is comprised of rivet  40 , wave washer  42 , and shoulder bushing  44 . Rivet joint  36  is comprised of rivet system  38 , a larger linkage connection hole  46  of a connecting link  37  and a smaller linkage connection hole  48  of a connecting link  37 . Rivet  40  is of unitary construction comprising rivet head  50 , rivet shoulder  52 , and tenon  54 . With reference to FIG. 6, a prior art rivet joint  36   a  is shown that includes fiber washer  144  interposed between connecting links  37   a,    37   b.    
         [0028]    As shown in FIGS. 7 and 8, shoulder bushing  44  is a unitary construction defined by shoulder bushing inner diameter  56 , shoulder bushing outer diameter  58 , washer outer diameter  60 , washer outer face  62 , washer inner face  64 , and bushing inner face  66 . As shown in FIGS. 4 and 5, shoulder bushing inner diameter  56  rotatably engages rivet shoulder  52 . Shoulder bushing outer diameter  58  rotatably engages the larger linkage connection hole  46  of connecting link  37 . Smaller linkage connection hole  48  of connecting link  37  is sized to fit tenon  54 . The thickness t 1  of shoulder bushing outer diameter  58  is less than the thickness t 2  of the associated connecting link  37  to allow wave washer  42  to fully engage connecting link  37 . As best depicted in FIG. 4, rivet joint  36  may contain a third connecting link  37  by utilizing a rivet  40  with either a longer rivet shoulder  52  or longer tenon  54 . With reference to FIGS. 4 and 5, rivet system  38  is assembled with a conventional riveting peening method applied to tenon  54 .  
         [0029]    Shoulder bushing  44  replaces a conventional oiled fiber washer  144  (as shown in FIG. 6) which functioned as an oil reservoir in a conventional rivet joint. In the conventional system, the rivet joint is assembled and painted using an electrostatic painting process. The fiber washer was then soaked with oil. The conventional system has a shortcoming in that the fiber washer requires lubrication after assembly and painting.  
         [0030]    The improved shoulder bushing  44  is constructed of material that is low-friction and self-lubricating when installed between metal connecting links  37 , thus eliminating undersired manufacturing inconsistencies. As a preferred embodiment, the shoulder bushing  44  is fabricated of nylon 6/6. However, a skilled practitioner will recognize that other suitable low-friction self-lubricating plastics may be utilized in the present invention. Rivet shoulder  52  extends through link  37   a  and shoulder bushing  44  to provide a metal-to-metal contacts between the rivet  40  and the link  37   b.  Thus, good electrical conductivity to the links  37   a,    37   b  is provided by the rivet  40  and the wave washer  42  to promote efficient electrostatic painting.  
         [0031]    Some conventional rivet systems, as shown in FIG. 6, utilize a bushing that faces the rivet head and floats between the rivet shoulder and first linkage connection hole to reduce rotational friction. The improved shoulder bushing  44  combines this bushing (if installed) and fiber washer in a one-piece construction to reduce the number of parts required for assembly. Moreover, the link  37   a  and the shoulder bushing  44  are permitted to slide axially on the rivet shoulder  52  which in combination with the wave washer  42  affords greater latitude for dimensional tolerance of the rivet joint  36 .  
         [0032]    Wave washer  42  provides an axial spring force within rivet joint  36  to prevent wobble of the joint while concomitantly allowing for tolerance variations in link  37   a  thickness. The metal construction of wave washer  42  provides an electrical circuit throughout pantograph linkage mechanism  34  which simplifies post-assembly electrostatic painting. As presently preferred, the wave washer is fabricated of a spring steel washer that is plastically deformed to provide the desired force when assembled. However, a skilled practitioner will recognize that other suitable materials and designs may be utilized in the present invention.  
         [0033]    With reference to FIGS. 9 and 10 a,  rivet joint  68  is shown as an alternate embodiment of rivet joint  36  wherein rivet shoulder  52  of rivet  40  is received within a spring shoulder bushing  70 . As best seen in FIG. 11, spring shoulder bushing  70  is of unitary construction and includes a bush portion  71  having a bushing inner surface  72  and a bushing outer surface  74 , and a washer portion  75  having a washer inner surface  76  and a washer outer surface  78 . The washer portion  75  of spring shoulder busing  70  is dished with washer inner surface  76  forming a concavity. Spring shoulder bushing  70  is preferably constructed of a self-lubricating plastic and more preferably of nylon.  
         [0034]    Spring shoulder bushing  70  is received within a larger linkage connection hole  46  of a connecting link  37  where bushing outer surface  74  and at least a portion of washer inner surface  76  are in contact with connecting link  37 . Rivet tenon  54  is received within a thrust washer  80  which is interposed between connecting links  37 . Thrust washer  80  is preferably constructed of bronze or zinc plated steel to reduce rotational friction between connecting links  37  and provide an electrical circuit connection between the connecting links  37 . Tenon  54  is also received within smaller linkage connection hole  48  of a connecting link  37 . A conventional riveting/peening process is used to assemble rivet joint  68 . When rivet joint  68  is fully assembled, thrust washer  80  is preferably in contact with rivet shoulder  52 . Spring shoulder bushing  70  applies an axial force acting circumferentially on rivet head  50  and connecting link  37  to reduce any wobble associated with rivet joint  68 .  
         [0035]    [0035]FIG. 10 b  discloses rivet joint  68   a,  essentially similar in construction as rivet joint  68  and including a third connecting link  37   c  with a larger linkage hole  46  interposed between connecting links  37   a,    37   b.  A larger bore thrust washer  82  is interposed between links  37   a  and  37   c  to allow the three links  37   a,    37   b,    37   c  to freely rotate. The bushing portion of spring shoulder bushing  70  in rivet joint  68   a  preferably has a greater axial length than the bushing portion of spring shoulder bushing  70  in rivet joint  68 . In this manner, larger linkage hole  46  of third connecting link  37   c  can contact the bushing outer surface  74  which provides for a low friction joint with reduced wobble. Additionally, spring shoulder bushing  70  reduces the lateral freeplay of pantograph linkage mechanisms  34  that are associated with the use of wave washer  42 .  
         [0036]    With reference to FIGS. 12 a,    12   b,    13   a  and  13   b,  an alternate embodiment of thrust washers  80 ,  82  is shown as a low friction thrust washer  90 . Low friction thrust washer  90  includes an annular surface  92 , a central aperture  94  and at least one eccentric aperture  96 . Preferably, a plurality of eccentric apertures  96  (FIG. 12A) are formed in low friction thrust washer  90  to minimize material requirements. Eccentric aperture  96  is formed through thickness  98  of low friction thrust washer  90 . A metal contact  100 , as discussed below, is interposed through eccentric aperture  96 . Low friction thrust washer  90  is preferably injection molded with a self-lubricating plastic and more preferably of nylon 401.  
         [0037]    When rivet joints  68 ,  68   a  (FIGS. 10 a,    10   b ) are assembled, rivet  40  is interposed through central aperture  94 . Central aperture  94  is sized to accommodate tenon  54  if low friction thrust washer  90  is substituted for thrust washer  80 . Central aperture  94  is sized to accommodate spring shoulder  70  if low friction thrust washer  90  is substituted for thrust washer  82 .  
         [0038]    [0038]FIGS. 13 a  and  13   b  show metal contact  100  in a pre-assembled form. Metal contact  100  is preferably an extruded brass field rivet that includes a flange  102  and a shaft  104  having an outer diameter  106  and a depth  108 . Shaft  104  of metal contact  100  is preferably hollow with an inside diameter  110 . When low friction thrust washer  90  is fully assembled, shaft  104  is interposed through an eccentric aperture  96 . Outer diameter  106  is preferably sized for a slight interference fit with eccentric aperture  96 . Flange  102  is secured against annular surface  92  concentric to eccentric aperture  96 . Depth  108  is slightly greater than thickness  98 . In this manner, distal end  112  of shaft  104  can be flared to secure metal contact  100  within eccentric aperture  96 . When rivet joints  68 ,  68   a  are fully assembled, metal contact  100  will abut both immediately adjacent connecting links  37 . While metal contact  100  is described as a brass rivet, it would be understood by one skilled in the art that metal contact  100  could be any electrically conductive material formed with low friction thrust washer  90  in such a manner so as to allow for electrostatic painting of pantograph linkage mechanisms  34 .  
         [0039]    In this manner, low friction thrust washer  90  will greatly minimize the metal-to-metal frictional contact surface area within rivet joints  68 ,  68   a  while providing adequate electrical contact between connecting links  37  to allow for electrostatic painting of pantograph linkage mechanisms  34 .  
         [0040]    With reference to FIGS. 14 a  and  14   b,  another alternate embodiment of thrust washers  80 ,  82  is shown including an electrically conductive plastic thrust washer  114 . Thrust washer  114  includes a first face  116 , a central aperture  118 , and a second face  120 . First and second faces  116 ,  120  have substantially identical surface areas. Thrust washer  114  includes a surface area to thickness ratio of between about 2:1 and about 20:1. In an exemplary embodiment, thrust washer  114  includes a thickness dimension of about 0.030 in., an outer diameter of about 0.75 in., and a central diameter of about 0.380 in. Therefore, an exemplary thrust washer  114  includes a surface area to thickness ratio of about 12:1. One skilled in the art will recognize that the specific dimensions of the washer(s) may vary depending on the requirements of a given application. For example, the dimensions of the washers may range from about ½ to about 1 inch in diameter and between about 0.020 to about 0.070 inches in thickness. Alternatively, thrust washer  114  may include a plurality of eccentric apertures, similar to apertures  96  illustrated in FIGS. 12 a  and  12   b.    
         [0041]    Thrust washer  114  is preferably injection molded with a composition including a self-lubricating plastic material and an electrically conductive material to provide suitable continuity therethrough. In an exemplary embodiment the composition includes about 70% nylon 6/6 and about 30% carbon fiber. Suitable washers for the present invention manufactured by SCP Plastics, Inc. of Boonville, Miss. and available from Raffel Product Development Co., Inc. of Saukville, Wis. These properties simultaneously provide a washer having sufficient lubricity and abrasion resistance to the moving links  37  and rivet with which it rotationally engages. Furthermore, these properties provide a washer having a surface hardness high enough to prevent the rivet from penetrating first face  116  during the riveting process. It should be appreciated that alternative materials and/or compositions having similar properties may also be implemented, understanding that a thrust washer  114  having a relatively high durometer tends to be more rigid than a thrust washer  114  having a relatively low durometer and, therefore, may be more susceptive to fracturing under loading in the above-described pivot joint application. Additionally, compositions having a higher ratio of electrically conductive material, such as carbon, to self-lubricating material, such as nylon, may be less flexible and, therefore, more susceptible to fracture.  
         [0042]    When rivet joints  68 ,  68   a  (FIGS. 10 a,    10   b ) are assembled, rivet  40  is interposed through central aperture  118 . Central aperture  118  is sized to accommodate tenon  54  if thrust washer  114  is substituted for thrust washer  80 . In this configuration, first face  116  engages connecting link  37   c  and second face  120  engages connecting link  37   b.  Central aperture  118  is sized to accommodate spring shoulder  70  if thrust washer  114  is substituted for thrust washer  82 . In this configuration, first face  116  engages connecting link  37   a  and second face  120  engages connecting link  37   c.  In this manner, thrust washer  114  provides for a low friction joint and a closed electrical circuit between the connecting links  37 . Electricity is conducted through thrust washer  114  and substantially uniformly across faces  116 ,  120  to enable electrostatic painting of the pantograph linkage mechanisms  34 . Specifically, thrust washer  114  ensures that a sufficient voltage potential between the linkage to be painted and the paint being applied during the e-coat paint process.  
         [0043]    One skilled in the art will appreciate that spring shoulder bushing  70  may also be fabricated with a conductive plastic material similar to thrust washer  114  described above. In this manner, conductivity through the pivot joint may be further enhanced for electrostatic painting, while maintaining the integrity of the rivet joint.  
         [0044]    The foregoing discussion discloses and describes exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.