Abstract:
A rocker chair base assembly employs a set of unitary composite cam members to enable a user to engage in a rocking motion with a chair mounted over the assembly. Each cam member presents a rigid body with a set of laterally projecting sleeves. A first set of angle cross members serve to interconnect longitudinal rails on which the cam members reside, and a second set of angle cross members serve to interconnect adjacent cam members. Specifically, the laterally projecting sleeves of each cam member present a mating angle profile for slidably receiving therein and securely attaching with longitudinal end regions of the second set of angle cross members.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     Rocker chairs, including recliners with a rocking feature, typically have a base assembly for supporting the superstructure of the chair on a floor. As an example, rocker chairs may include various linkage systems for supporting a seat frame, a footrest, and other chair occupant support structures through movements of the chair from an upright seated position to partially and fully reclined positions, and back. Additionally, such chairs often employ a rocking motion limiting mechanism. Over time, the rocking motion limiting mechanism of a typical rocker chair encounters many stress cycles and becomes prone to fatigue failure. For instance, if compression or extension springs are utilized in the rocking motion limiting mechanism, the many cycles of stretch or elongation of the spring body may eventually lead to structural failure. One way to handle this issue is to utilize a more substantial spring (e.g., larger diameter wire) in the design of the rocking motion limiting mechanism. However, a significant drawback of larger springs is increased force that is require to stretch the spring, which can impede the chair occupant&#39;s ability to engage in a rocking motion. As a result, it has proven difficult to provide a rocker chair design that is easy for the user to “rock” while providing to be reliable over time. 
     SUMMARY OF THE INVENTION 
     A brief overview of the rocker chair base assembly and its components follows immediately below. A more detailed description is provided in the Detailed Description of the Invention section. 
     Embodiments of the present invention provide a rocker chair (rocker-recliner) base assembly employing a set of unitary composite cam members to enable a user to engage in a rocking motion with a chair mounted over the assembly. 
     In one aspect, the rocker chair base assembly includes first and second sets of angle cross members for interconnecting both the set of composite cam members and a set of spaced apart longitudinal rails upon which the cam members are located for rolling contact therewith during a rocking motion. Each composite cam member is formed of a rigid body and a set of projecting sleeves extending laterally from the rigid body. The rigid body is formed with a lower contact surface presenting an arcuate longitudinal profile, enabling the rolling contact on an upper engagement surface of one of the longitudinal rails. Each sleeve is configured to present a mating angle profile for slidably receiving therein and securely attaching with longitudinal end regions of the second set of angle cross members, thereby interconnecting one composite cam member of the set of composite cam members with another composite cam member of the set of composite cam members. Additionally, a rocking motion limiting mechanism is securely attached to the first set of angle cross members and to the set of projecting sleeves of each composite cam member, thereby coupling the composite cam members to the first set of angle cross members for securely positioning the composite cam members on the longitudinal rails. 
     Additional features of the invention will be set forth in part in a description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are employed to indicate like parts in the various views: 
         FIG. 1  is a perspective view of a rocker chair base assembly incorporating a set of unitary cam members in accordance with one embodiment of the present invention; 
         FIG. 2  is a side elevational view of the rocker chair base assembly incorporating the unitary cam members; 
         FIG. 3  is a front elevational view of the rocker chair base assembly incorporating the unitary cam members; and 
         FIG. 4  is a close-up fragmentary perspective view of a portion of the rocker chair base assembly showing one of the unitary cam members. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings, and in particular to  FIGS. 1 and 2 , a rocker chair base assembly  100  is illustrated that incorporates a set of unitary cam members  102 , also referred to herein as cam members  102   a  and  102   b . The cam members  102  are interconnected with one another through a set of upper cross members  104  for proper positioning of each cam member  102  upon one of a set of parallel longitudinal rails  106  of the base assembly  100 . In this way, the longitudinal rails support a forward and rearward rocking motion on the rails  106  by the cam members  102 , with the cam members  102  supporting the weight of the chair frame and other superstructure of a rocker-recliner chair (not shown). The rocker chair base assembly  100  further includes a set of lower cross members  108  connected on opposed longitudinal ends  110  with the longitudinal rails  106  and a set of rocking motion limiting mechanisms, for instance, in the form of rocker spring assemblies  112 . Each rocker spring assembly  112  interconnects the lower cross members  108  with the upper cross members  104  and thereby indirectly couples the cam members  102   a  and  102   b  with the rails  106  as explained more fully herein. The cross member longitudinal ends  110  may be attached to opposed side regions  113  of each longitudinal rail  106  by welding or other attachment means. In one embodiment, the upper and lower cross members  104  and  108  are each formed as longitudinally extending “L” shaped angle members with a vertical flange portion  115  and a horizontal flange portion  117  joined along a common bend. The horizontal flange portion  117  is preferably attached with each longitudinal rail side region  113  at an elevation significantly lower than the elevation of an upper engagement surface  126  of the respective rail  106  upon which the cam members  102  engage in the forward and rearward rocking motion. This provides the advantage of a lower seating for the rocker spring assemblies  112 , the benefits of which are more fully explained herein. However, in certain embodiments, it should be understood that the upper and lower cross members  104  and  108  may possess a variety of cross-sectional angle configurations, such as those generally referred to as “J” shaped, “U” shaped, “Z” shaped, or other configurations. 
     The cam members  102  are preferably formed as rigid composite structures from polymeric material. For instance, the cam members  102  may be formed of glass-filled nylon, polypropylene, or a combination of the these materials. Other materials may be selected as a matter of design choice. The composite cam members  102  may be formed by molding processes, such as injection molding, and certain portions of the cam members  102  may be machined to form the finished product. The composite nature of the cam members  102  allow for improved integration into a rocker chair base assembly  100 , resulting in shorter assembly times and a more reliable product. The use of composite materials enables the cam members  102  to be manufactured to tight tolerances and with consistent material properties throughout the structure. Furthermore, composite cam members provide the advantage of being able to withstand repeated loading cycles while maintaining sufficient structural integrity. 
     With continued reference to  FIGS. 1 and 2 , and additional reference to  FIGS. 3  and.  4 , each of the cam members  102  has a main body  119  and a set of projecting sleeves  114  extending laterally from the main body  119 . In one embodiment, the projecting sleeves  114  present a mating angle profile for accepting a longitudinal end regions  130  of one of the upper cross members  104 , and in particular, a member  104  having the vertical flange portion  115  and horizontal flange portion  117 . The main body  119  of each cam member  102  includes an upper portion  116  from which the sleeves  114  project, a lower portion  118  where a contact surface  120  is formed, and a vertically oriented web  121  spanning between the upper portion  116  and the lower portion  118 . The web  121  has a plurality of strengthening ribs  122  extending generally from the upper portion  116  to a location at or near the lower portion  118  to aid in carrying the vertical load induced by the chair occupant and the weight of the chair. Preferably, some or all of the ribs  122  do not extend downwardly to the contact surface  120 , as typical molding processes for the cam member  102  could result in the ribs  122  creating small deflections in the contact surface  120  that may be felt by the chair occupant during a rocking motion on the longitudinal rails  106 . 
     For a smooth rocking motion, the contact surface  120  of the cam member  102  has an arcuate longitudinal profile. As such, the contact surface  120  is configured to move in rolling engagement with a top surface  126  of the longitudinal rails  106 . Optionally, a powder coat may be applied to the top surface  126  of the longitudinal rails  106  in order to increase the friction between the top surface  126  and the contact surface  120  to reduce slippage during rocking. 
     Laterally oriented through holes  128  are generally positioned at the upper portion  116  of the main body  119  to serve as attachment points for a rocker-recliner chair frame to couple with the rocker chair base assembly  100  through each cam member  102 . For instance, fasteners (not shown) may be inserted into through holes  128  and through a feature of the rocker-recliner chair frame to accomplish coupling with the rocker chair base assembly  100 . Those of skill in the art will appreciate that other attachment means may be selected. 
     In assembly, the longitudinal end regions  130  of the upper cross members  104  are inserted into the sleeves  114  and vertically oriented apertures (not shown) of both the upper cross members  104  and the sleeves  114  are aligned so that a fastener  132  inserted therethrough secures one of the upper member end regions  130  within one of the sleeves  114 . Specifically, in one embodiment, the vertically oriented apertures are formed in the horizontal flange portion  117  of the upper cross members  104  for accepting the fasteners therethrough. This particular design also ensures proper lateral alignment between the contact surface  120  of the cam member  102  and the top surface  126  of the longitudinal rails  106  by selecting upper cross members  104  of an appropriate length. It should be understood that the term “sleeve” as used herein may refer to both a sleeve that completely circumscribes or surrounds the upper member end region  130  or a sleeve that partially surrounds the upper member end region  130 . Accordingly, in embodiments, the sleeve  114  may surround both the top and bottom sides of the horizontal flange portion  117  of the upper cross members  104 , or may overlie either the top or bottom sides of the portion  117 . 
     In one embodiment of the rocker chair base assembly  100  illustrated in  FIG. 1 , one of the cam members  102   a  has sleeves  114  projecting laterally to the left and the other cam member  102   b  has sleeves  114  projecting laterally to the right (according to the orientation of a chair occupant), so that the sets of sleeves  114  on the opposed cam members  102   a ,  102   b  are directed towards one another. With additional reference to  FIG. 3 , outward facing and inward facing lateral side regions  134 ,  136  of each cam member  102  are generally mirror images of one another, except that the inward facing region  136  includes the sleeves  114  as well as a brace  138  extending from the vertically oriented web  121  to support each sleeve  114 . 
     With continued reference to  FIGS. 1-4 , in one embodiment, each rocker spring assembly  112  is secured between the sleeves  114  of one cam member  102  and the lower cross members  108  to thereby regulate a rocking motion by the composite cam members  102  on the upper engagement surfaces  126  of the longitudinal rails  106 . Specifically, the spring assemblies  112  each include a pair of spring coils  140  with an upper portion  142  thereof coupled with an upper bushing  144  and a lower portion thereof  146  coupled with a lower bushing  148 . Each lower bushing  148  spans between the horizontal flange portion  117  of the lower cross members  108  and each upper bushing  144  spans between the sleeves  114  at the point of attachment with the upper cross members  104 . The upper bushings  144  and lower bushings  148  each have vertically oriented apertures (not shown) to enable fasteners  132  to be inserted therethrough for mounted to the sleeves  114  and the lower cross members  108 , respectively. In one embodiment, the same fasteners  132  that secure the upper cross members  104  and the sleeves  114  together also secure the upper bushings  144  thereto. With respect to the lower cross members  108 , vertically oriented apertures (not shown) are formed in the horizontal flange portion  117  of members  108  for alignment with the apertures of the lower bushings  148  and receiving the fasteners therethrough. This design provides the advantage of a single assembly step for mounting both the upper cross members  104  and the upper bushings  144  to the sleeves  114 , and mounting the lower cross members  108  with the lower bushings  148 , by use of the fasteners  132 . Alternatively, in a configuration where the sleeves  114  do not completely circumscribe the upper member end regions  130 , and thereby leave the bottom side of the horizontal flange portions  117  of the upper cross members  104  exposed, the upper bushings  144 , via fastener  132 , connect directly with the horizontal flange portion  117 . 
     In embodiments, by locating the horizontal flange portion  117  of the lower cross members  108  at such a low elevation with respect to each longitudinal rail upper engagement surface  126 , the lower seating for the rocker spring assemblies  112  is achieved. Specifically, the lower bushings  148  and the spring coil lower portions  146  are positioned lower than the longitudinal rail upper engagement surface  126 , as best seen in  FIG. 2 . This configuration ensures that excessive spring elongation or extension (stretch) is not encountered during a given range of forward and rearward rocking motions. Additionally, because less spring elongation is required for a given range of rocking motions, less force is required by the chair occupant in order to fully “rock” the chair. In one embodiment, the height or vertical length of the spring coils  140  above the horizontal plane defined by the longitudinal rail upper engagement surface  126  is approximately the same as the height of the spring coils  140  below the same plane. Thus, a vertical midpoint of the spring coils  140  is basically in the same plane as the longitudinal rail upper engagement surface  126 . This provides a good balance in that the height centered spring (i.e., vertically centered with respect to the longitudinal rail upper engagement surface  126 ) achieves less spring elongation, and thus less stress, while still providing a full range of rocker cam motion without excessive resistance to the user&#39;s force input. 
     The coupling of the upper and lower portions  142  and  146  of the spring coils  140  with the respective upper and lower bushings  144  and  148  is best seen in  FIGS. 1 and 4 . Each of the upper and lower bushings  144  and  148  has a first sidewall  150  formed with an aperture  152  through which the spring coil upper and lower portions  142  and  146  extend, as well as a second sidewall  156 . Interconnecting the sidewalls  150  and  156  of each of the upper and lower bushings  144  and  148  is a base portion from which a pair of clips  154  extend. These clips  154  aid in holding the spring coils  140  in place on the bushings  144  and  148 . 
     Those of skill in the art will appreciate that one or more additional cam members  102  and a corresponding number of longitudinal rails  106  may be integrated into the design of the rocker chair base assembly  100 . For instance, another parallel longitudinal rail  106  may be positioned between the existing rails  106  with a split in the lower cross members  108  where the additional rail  106  may be located. In such a design, each additional cam member  102  would have sleeves projecting from both outward facing and inward facing lateral side regions  134  and  136 , thereby extending in opposed lateral directions. Additionally, multiple rocker spring assemblies  112  (or simply an additional number of spring coils for each pair of upper and lower bushings  144  and  148 ) may be coupled with each cam member  102  in situations where the projecting sleeves  114  are sufficiently long as to provide appropriate mounting locations for the rocker spring assemblies  112  along the length of the upper cross members  104 . 
     As can be understood, the unitary cam member  102  design of the present invention provides a durable product that is well integrated with other components of a rocker chair base assembly  100 . The cam members  102  facilitate ease of manufacture of a rocker chair base assembly  100  with a reliably positioned interface between the cam member contact surface  120  and the longitudinal rails  106  which support the rocking motion. 
     Furthermore, since certain changes may be made in the above invention without departing from the scope hereof, it is intended that all matter contained in the above description or shown in the accompanying drawing be interpreted as illustrative and not in a limiting sense. It is also to be understood that the following claims are to cover certain generic and specific features described herein.