Abstract:
A rocking chair has a flexible joint between a chair base and a chair component permitting rocking action. The flexible joint includes a housing with a plurality of internal surfaces. A plurality of compressible rods are disposed within the housing and a rigid member extends among the rods to engage the rods against the internal surfaces of the housing. The rigid member is attached to either the chair base or the chair component while the housing is then attached to either the chair base or the chair component whichever is not attached to the rigid member.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a rocking chair in which a chair component is movable in a rocking motion with respect to a chair base. 
   There are many types of rocking mechanisms that permit movement of a chair component with respect to a chair base. One such rocking mechanism that uses a pair of coil springs is the described in the Bottemiller et al. U.S. Pat. Nos. 2,916,084 and 4,786,106. 
   Other types of rocking mechanisms are also described in Bottemiller et al. U.S. Pat. No. 4,371,142 and the Apissomian U.S. Pat. No. 4,411,468. 
   SUMMARY OF THE INVENTION 
   The present invention includes a rocking chair which has a flexible joint between a chair base and a chair component permitting rocking action. The flexible joint includes a housing with a plurality of internal surfaces. A plurality of compressible rods are disposed within the housing and a rigid member extends among the rods to engage the rods against the internal surfaces of the housing. The rigid member is attached to either the chair base or the chair component while the housing is then attached to either the chair base or the chair component whichever is not attached to the rigid member. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view of the rocking chair of the present invention. 
       FIG. 2  is a sectional view of the rocking mechanism. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A rocking chair construction of the present invention is generally indicated at  10  in  FIG. 1 . The rocking chair  10  has a chair component  12 , a base  14  and a rocking mechanism  16  that connects the chair component  12  and the base  14 . The rocking mechanism  16  permits the chair component  12  to move in a rocking manner in relation to the base  14 . Preferably, although not necessary, the chair component  12  also rotates 360° with respect to the base  14 . 
   The chair component  12  includes a back portion  18  and a seat portion  20  and left and right arm sections  22  and  24  which extend between the seat portion  20  and the back portion  18 . Although a specific chair component is described and illustrated, any type of a chair component that can be secured to the rocking mechanism  16  is within the scope of the present invention. 
   The base  14  as illustrated in  FIG. 1  is a pedestal type base have a pedestal portion  28  attached to a ground engaging ring portion  26 . The pedestal portion  28  is attached to the ring  26  through three finger sections  30  that engage the ring  26  at three substantially equally spaced apart points. The finger sections  30  converge at an apex  32  of the pedestal portion  28 . The apex  32  includes an aperture  34  whose axis is disposed substantially vertically. Although a pedestal base is described and illustrated other bases which can be secured to the rocking mechanism that provide sufficient stability for a rocking motion are within the scope of the present invention. 
   The rocking mechanism  16  includes left and right support arms  36  and  38 , a housing  40 , a plurality of resiliently compressible rods  42 ,  43  and a separator bar  44 . 
   The housing  40  includes an upper half  46  and a lower half  48  which are secured to each other by a plurality of screws  50  to form a chamber  52  as best illustrated in  FIG. 2 . The chamber  52  has a plurality of internal surfaces  53 . The resiliently compressible rods  42 ,  43  are disposed within the chamber  52  and separated from each other by the bar  44 . The resiliently compressible rods  42  are disposed in a parallel relationship with each other. Similarly, the rods  43  are also disposed in substantial parallel relationship with each other. For each rod  42 , there is an adjacent rod  43  positioned such that longitudinal axis of both rods are substantially co-axially disposed. It should be understood, that a rod of one length (running the length of the housing) can be substituted for each combination of rods  42  and  43 . The rods  42  and  43  are retained in corners  55  by engaging adjacent surfaces  53  of the chamber  52 . The separator bar  44  extends through the chamber  52  separating the rods  42 ,  43  and helping to retain the rods  42 ,  43  within the corners  55 . 
   The separator bar  44  is fixedly attached at a left end  52  to the left support arm  36  and at a right end  54  to the right support arm  38 . The left and right support arms  36  and  38  are fixedly attached to the chair component  12  by suitable screws or other fasteners or by welding or other known methods of attachment. The manner of attachment is not important to the present invention. 
   The lower half of the housing  48  is fixedly attached to a downwardly extending shaft  56 . A sleeve  58  extends through the aperture  34  into the base  14  securing the shaft  56  to the base  14 . The sleeve  58  receives the shaft  56  such that the shaft  56  rotates within the sleeve  58 . It will be understood that the chair component is rotatable 360° relative to the base  14 . 
   Although the housing is described and illustrated as being attached to the base  14  and the bar  44  being attached to the chair component  12 , the attachments could be reversed. The housing could be attached to the chair component while the bar  44  is attached to the base. 
   The rods  42 ,  43  are preferably made from a polyurethane elastomer. An important characteristic of the rods  42 ,  43  are that the rods are resiliently compressible. The rods are preferred to be compressible. By resiliently compressible is meant that the material that the rods are made of has the ability to recover and return to its original shape or position after having been compressed. 
   As the chair component  12  is rocked back and forth, the separator bar  44  through its connection to left and right support arms  36  and  38  is moved along its longitudinal axis back and forth as indicated by arrow  60 . Surfaces  62  of the separator bar  44  engage the resiliently compressible rods  42 ,  43 . Since the rods  42 ,  43  are compressible, the rods  42  permit the bar  44  to turn along its longitudinal axis as indicated by arrow  60  thereby permitting a rocking motion to the chair component  12 . The rods  42 ,  43  provide a resistance to the movement of the chair component which is desirable in a rocking mechanism. Since the rods  42 ,  43  are also resilient, that is, the rods are capable of returning to their original shape or position after having been compressed, the chair component  12  will return to its original position since the rods  42 ,  43  force the separator bar  44  to move back to its original position. 
   Preferably, the polyurethane rods have a durometer of approximately 60 Shore A hardness. The stiffness (resistance) of the rocking motion is changeable by durometer and rod diameter size or thickness. Theoretically, there is no lower limit to the durometer needed other than that the rocking motion will not be stiff enough if too low of a durometer is chosen. However, at higher durometers, the rods  42 ,  43  may start to take a permanent set and shape, and although providing a rocking motion, such rods will not provide as smooth of a rocking motion to the chair component  12 . In the example of polyurethane, polyurethane will take a permanent set and shape at a durometer of approximately 80 Shore A hardness and higher. For materials other than polyurethane, the upper limit may be a different durometer value. It has been found that for polyurethane a suitable durometer is approximately 50 to 65 Shore A hardness. 
   While polyurethane has been given as a specific example, other materials may be used such as other elastomers. It is believed that other materials will work as well as polyurethane as long as the material is resiliently compressible. Synthetic and natural rubbers will also produce a rocking motion although not as desirable as the rocking motion produced by polyurethane. 
   Although the separator bar is illustrated in  FIG. 2  as having a square cross section, other cross section configurations are includeable within the present invention. Other four sided polygon configurations such as rectangular are suitable. Other multiple sided polygon configurations such as a triangular cross section with three surfaces engaging the rods may be suitable if the rods encased within the housing are held in position. 
   Similarly, the cross sectional configuration of the rods does not have to be circular. Depending on the internal shape of the chamber of housing, the rods may have a different cross sectional configuration other than circular. The primary characteristic needed is that the rods  42 ,  43  engage a surface of the bar  44  when the bar is turned about its axis and to provide some resistive force during the rocking motion. 
   Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.